2         BACKGROUND

2.1        REASON FOR FOCUSING ON HYDROPOWER PROJECTS

At every course of action, technology is developed as per human needs which have both positive as well as negative impacts. The rate of development of world is increasing day by day and it has pronounced negative impacts such as depletion of natural resources, environmental degradation, etc. The scenario of energy consumption is at the increasing rate. This causes depletion of non-renewable and exhaustive sources of energy, sustainable development which means that our children should get at least as much resource that we are consuming at present. So, energy consumers should be keen on using of non exhaustive and renewable sources of energy. Hydropower, one of the most reliable and common renewable sources of energy is abundantly available in the hilly regions like Nepal. Again, hydraulic conveyance circuit can be beneficial for multipurpose use (irrigation, water supply, etc.). Hydropower production does not consume water, so it is considered as renewable source of energy.

Due to presence of abundant water resources and potential hydropower sites, there is huge possibility of hydropower power production in Nepal. Large projects involve huge amount of funds and the development period is also long. Hence, activities regarding development of small hydropower projects are accelerating these days which is technically, financially and socially sustainable at the present scenario.

2.2         HISTORY OF HYDROPOWER DEVELOPMENT

 Use of energy generated from water has been started since the very beginning of human civilization. Michael Faraday demonstrated that mechanical energy could be converted into electrical energy and vice-versa, in 1831, development and use of electrical energy began gaining momentum after 1890. By 1900, hydropower plants had become a common source of obtaining electricity. In the early 19th century. progress in the hydropower development was slow because of less efficiency in power transmission over the long distance. The pace of hydropower development increased dramatically after 1930. United States made a policy to invest in water based projects to create jobs for unemployed and to stimulate Financial recovery in the country when it faced severe Financial hardship in 1929. In the former SovietUnion, hydropower was considered synonymous with industrialization and Financial prosperity after 1920.

After 2^nd world war, leaders of African and Asian nations has replicated the western US model to meet energy and water needs of their own countries and many large scale hydropower projects were built in India, Pakistan and Egypt between 1950 and 1980.

None of the projects in US, former Soviet Union and India had the objective of exporting energy to its neighboring to earn revenue for the country. In recent decades, the concept of production of electrical energy has been changed. Now, has been traded between two or more nations after agreement upon certain terms of trade. Exporting electricity to a neighboring country to earn revenue for the government is one of the stated objectives of developing large-scale hydropower projects in Nepal.

2.3        HYDROPOWER DEVELOPMENT IN NEPAL

Nepal has a huge hydropower potential. The average annual precipitation is about 1700mm (80% of which occurs during monsoon season from June to September). The total annual average runoff from Nepal's 6000 rivers is over 200 billion m .In face, the perennial rivers and the steep gradient of the country's topography provide ideal conditions for the development of some of the largest hydroelectric project in Nepal. The water storage potential of 88 billion m^3 and the diversified climate and the physical environment are the notable factors that account for large hydropower generation in Nepal. The distance between the agnatic plain at about 70 m from MSL to the Mt. Everest at 8848m from MSL is only about 170 km, and the steep slope accounts for high head for hydropower generation. Nepal's theoretical hydropower potential is estimated at 83,000 MW (Dr. Hari Man Shrestha) and out of this gross potential, 44,000 MW has been found technical feasible. At present, 93 dam's sites have been identified and 66 of these are found financially feasible with total generation capacity of about 42,000MW. However, the present situation is that Nepal has developed only approximate 1020.625MW of hydropower. Therefore, bulk of the Financial feasible generation has not been realized yet. Besides, the multipurpose, properly planned and managed, development of its rivers. If properly planned and managed, development of Nepal's storage potential could yield tremendous benefits to Nepal and its neighbors in the form of hydropower generation, flood control during the monsoon and flow augmentation for downstream irrigation.

Hydropower currently provides almost all of Nepal's electric power. Nepal's topography gives enormous scope for the development of hydro-electricity, which probably provides the only realistic basis for its further financial development. Small scale hydro plants are the most viable option for rural electrification. Large projects, however, in view of Nepal's limited financial resources, would probably require power export contracts with India as prerequisite. Energy through hydropower contributes to 95 percent of total electricity generation in Nepal. Until 2018, only 2.43 percent of the calculated potential 42000 MW had been realized. The benefit of the large scale hydropower has not been flowed to the majority of the people in Nepal, 90 percent on who lead in agriculture life. According to the population census of 2016, 90.7 percent of the people of Nepal have access to electricity, and are mostly urban.

First hydropower plant developed in Nepal was Pharping Hydropower station (500KW) IN 1911. But the progressive development was noticed only after the Sundarijal (600KW) and Panauti (2400KW) Hydropower Station came into operation after long interval of 23 and 29 years.

The completion of Dhankuta Hydropower station (240 KW) in 1971 was regarded as the bench mark of small hydropower development of Nepal. The establishment of small hydropower development board in 1975 was another milestone under which several small hydro schemes such as Jhupra (345 KW), Doti (200KW), Jhumal (200 KW) etc. were made during 1975 to 1985. Nepal Electric Authority (NEA), established 1975, responsible for generation, transmissions and distribution of electric power brought the revolution in hydropower development. Many potential sites for hydropower generation had identified by private consultancies and companies in collaboration with NEA.

Prior to 1960, all the hydropower stations were constructed through grant aid from friendly countries like the USSR (Panauti), India (Trisuli, Devighat, Gandak, Suajpura-Koshi), China (Sunkoshi), and Germany (Madhya- Marshyandi). Since 1970. Hydropower development took a new turn with the availability of bilateral and multilateral funding sources. The major donor countries in the period were Japan, Germany, Norway, South Korea, Canada, Finland, Denmark, Sweden and USA. The financial leading agencies were the World Bank, Asian development bank (ADB),Japanese bank of international cooperation (JBIC), Saudi fund for development,Kuwait fund and others.

From 1990s, subsequent to the adoption of the policy of financial liberalization, hydropower development took yet another turn with the private sector entering the arena. After formulating Hydropower Development Policy-1992 by the government of Nepal, many private sectors are involving towards power development. In order to encompass projects of various scales intended

for domestic consumption as well as to export hydropower, the former policy was replaced by the Hydropower Development Policy 2001 to provide further impetus to active participation of private sectors.

Development of hydropower in Nepal is a very complex task as it faces numerous challenges and obstacles. Some of the factors attributed to the low level of hydropower development are lack of capital, high cost of technology, political instability and lower load factors due to lower level of productive end-use and high technical and non-technical losses.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3         POWER MARKET IN NEPAL

3.1        HYDROPOWER POTENTIAL OF NEPAL

Nepal has a total hydropower potential of 83,000MW out of which about 42,000MW is assessed to be financially feasible (Dr. Hari Man Shrestha).

Table 1: Hydropower Potential of Nepal GW (Source: Water Resources of Nepal, CK Sharma)

River Basin	Theoretical	Technical	Financial
Saptakoshi	22.35	11.40	10.48
Karnali	34.60	24.36	24.00
Gandaki	17.92	6.73	6.27
Mahakali	1.58	1.13	1.13
Others	3.07	0.98	0.98
Total	83.29	44.60	42.15

 

About 6000 big and small rivers have been identified in Nepal carrying about 179 cubic million meters of water run-off annually. All the major river basins, except those of the southern rivers originated in Himalayan or Tibetan Plateau. Major achievements in the financial development of Nepal could be achieved through power harnessing of the vast water resource.

3.2        HYDROPOWER DEVELOPMENT OF NEPAL

 Although the first power plant has been constructed in Nepal 1911, expansion of more hydropower plants has been slow. Then other hydropower plants followed after 23 and 29yrs after the commission of the first one. The subsequent hydro projects came into service in a reasonable short interval. NEA (Nepal Electricity Authority) established 1985 is responsible for generation, transmission and distribution of electric power in Nepal.

NEA has classified the hydroelectric Projects into the following five groups:

1. Micro Hydro:    Less than 100KW

2. Mini hydro:      100KW to 1MW

3. Small hydro:     1 to 10MW

4. Medium hydro: 10 to 300MW

5. Large hydro:     more than 300MW

 

3.3        POWER DEMAND AND SUPPLY

Power is one of the main fundamental requirements for the modern and its demand is very high for the industrial development and domestic use. For the developing country Like Nepal is highly needed to improve the industrial sector which will help to reduce poverty through improvement of the economy and employments creation. According the NEA, energy demand forecast for the coming years is shown in Figure below.

According to the NEA annual report 2018, the total installed capacity in Nepal Electricity Authority's (NEA) Integrated system is 1074.135 MW including the 1020.625 MW hydro plants ,Total Thermal Power(NEA) 53.410 MW and total Solar Power 0.1MW.Currently, the peak demand is about1300 MW and the deficit is 225MW and the country is facing acute shortage of energy especially during the dry season.

 

 

                                  

 

 

 

    SOME UNDER CONSTRUCTION POWER PROJECT

 

Arun III                     -900 MW                                 Khani khola             -30MW

Upper Tamakoshi      -456 MW                                Kulikhani III            -14 MW

Rasuwagadhi             -111 MW                                Mistri Khola            -42 MW

Middle Bhotekosi      -102 MW                               Gamgadhi                - 0.8 MW

Lower Sanjeen           -42.5                                      Iwa Khola                -9.9 MW

Lower Modi              -20 MW

Upper Sanjeen           -14.8 MW

Rudhi Khola              -8.8 MW

Upper Naugad Gad    -8 MW

3.4         POWER DISTRIBUTION PLAN

The need to extend distribution over the country is reflected from the fact that 85% population of the country is not getting electricity as a source of energy. So, the distribution of electricity should be done strategically. NEA has taken systematic studies of carrying out rural electrification and distribution system reinforcement (DSR) feasibility on district-wise basis. NEA intends to undertake these works with multi-source financing. Also, Nepal Government contributes to rural electrification scheme on an annual basis with an increasing magnitude in the year, 1999/2000, outlay being approximately 4.5 million US dollar. NEA and Nepal Government are jointly working for the electrification of rural areas. To cope with this objective, micro and small hydropower are the better options in the present scenario.

 

 

 

 

 

 

 

3.5          LEGAL PROVISIONS FOR INVESTMENT

 

Hydropower industry is one of the major industries with wider scope in Nepal. For an industry to prosper there should be support of government policies and legal provisions. Only the potential cannot do the development of a nation if the policies cannot be harnessed. Clearly defined conditions and attractive policy are always essential to harness the innumerous resources. Realizing this fact, Nepal Government has developed certain policies.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4         HYDROLOGY

4.1        INTRODUCTION

Hydrology is described as the science associated with the occurrence, circulation and distribution of water on land, atmosphere and underground; it also studies about the physical and chemical properties of water and their reaction with the environment. The various processes involved are precipitation, evaporation, infiltration, runoff, groundwater flow and stream flow. 

Since it is evident that a hydropower project is fundamentally dependent on the hydrological inputs of that location, it becomes necessary that the hydrological processes and characteristics required for the project such as:-precipitation, runoff, stream flow, area of catchment in a distinctive zone i.e. snow clad zone, vegetation cover, slope of land in catchment etc. be prudently studied and analyzed. The design of a stable, economic and deft functioning project is excessively reliant on the water characteristics or the flow. The installed capacity at which the project is understood to run for the entirety of the project span, bases on the mean monthly flow whereas the physical aspects of project rely on the flood flow analysis of the river. Here in our study as per the location, the type of river (gauged or ungauged) and data available, we carried out some hydrological calculations based on the following items such as:-stream flow, precipitation data, area of catchments, land slope, ground cover coefficients etc.  

4.2        Objective of  Hydrological Investigations

Hydrological investigations performed for design of headworks of run-of-river hydropower projects were aimed at achieving the following objectives:

 

Providing input for the selection of return period for inflow design flood, construction diversion flood and low flows.

Developing flow duration curves mean monthly hydrographs, rating curves and water surface profiles at the headworks.

4.3        Drainage Area Characteristics

Information on the physiographic characteristics of the drainage area, such as the latitude, altitude, area and shape of the basin, length of main channel, gradient of channel and basin, etc., were derived from topographic maps 1:50,000 (sheet No.2884 09)  published by the Survey Department, GoN. These data were used in the calculation of various hydrological parameters.

         

4.4        Hydrological and Meteorological Data

Hydro-meteorological data from the hydrometric and meteorological stations existing in and around the river basin were obtained from publications of the Department of Hydrology and Meteorology (DHM), GoN.

 

                                                                                                                                       Source: Google Earth  

                                     Fig 3: Rainfall stations near the catchment

4.5        THE CATCHMENT

Madme Khola is the tributary of Madi Nadi river and has catchment area of 36.33 km².

The catchment area above permanent snow line (EL.5000 m) about is 8.9 km² and the catchment area above(EL.3000) is 25.91 km² .the upper part of the catchment is confined by mountains.

The upper part of the catchment has snow, which contribute to sustained flow during the dry season.The stiffness of the topography of the area contributes not only to rapid flooding but also to a high erosion rate and high sediment carrying capacity.

 

Fig 4: Madme Khola Hydropower Project Catchment Area at Intake

 

 

 

 

 

 

 

 

 

4.6        Long-term Stream Flow Analysis

The long term flow analysis is carried out to obtain the average discharge that will be available for us in the river for the useful life of the project. This analysis will provide us with the average monthly discharge and then these values can be used to obtain the flow duration curve and design discharge of the project.

 

4.6.1      Importance

The long term flow analysis is very critical as it will provide the design discharge of the project. The optimization of the installed capacity of any hydropower project is done with the help of long term long term stream flow data. These data are used to formulate the Flow Duration Curve, and the discharge exceeding certain percentage of time is used for the optimization between the cost of the project and the benefit from the power revenue. This eventually leads the healthy economics of the project.

 

4.6.2      Flow Duration Curve

The flow-duration curve is a cumulative frequency curve that show the percent of time specified discharges were equaled or exceeded during a given period. It combines in one curve the flow characteristics of a stream throughout the range of discharge, without regard to the sequence of occurrence. If the period upon which the curve is based represents the long-term flow of a stream, the curve may be used to predict the distribution of future flows for water-power, water-supply, and pollution studies. 

 

It is simply obtained by plotting the discharge as ordinate and the percentage of time duration for which that magnitude or more is available as abscissa. In hydropower project, flow duration curves are widely used to assess the dependability of the discharge. Basically these are used in assessing the dependable power in runoff river plant with or without pondage.

 

                                      Fig 5: Flow Duration Curve

 

4.6.3        Methods used for long term flow analysis

•      Catchment Area Ratio Method 

•      WECS/DHM Method (WECS/DHM, 1990)

•      MIP Method

4.6.3.1         Catchment Area Ratio Method 

If two basins are hydro-meteorologically similar, data extension may accomplished simply by multiplying the available long-term data at the HSC with the ratio of the basin areas of the base station (proposed site under study) and the index (HSC) station. More accurate results were obtained using Dicken‟s flood formula,

Q_b=Qi*()^3/4Where,Q_b and Q_i are the discharges at the base and index stations, respectively, and A_b and A_i are the corresponding basin areas.

WECS/DHM Method

This method is developed for predicting the river flows for catchment areas larger than 100 sq km. of ungauged rivers based on hydrological theories, empirical equations and statistics. In this method, the total catchment area, areas between 5000 m to 3000 m are required as input. Flow contribution per unit area for 5000 m to 3000 m and from lower elevations i.e. below 3000 m is assumed to be in different proportion during flood. However, for long term average monthly flows all areas below 5000 m are assumed to contribute flows equally per sq. km. area. The average monthly flows can be calculated by the equation:

Q _mean= C×(Total basin area)^A1×(Basin area below 5000m+1)^A2×(Monsoon wetness index)^A3

            Where,   C, A1, A2, A3 are constants derived from the regression analysis.

A is the catchment area in Km².

Q is discharge in m³/sec

Table 4: Value of constants for WECS Method

Month	C	A1	A2	A3
January	0.0142	0.0000	0.9777	0.0000
February	0.0122	0.0000	0.9766	0.0000
March	0.0100	0.0000	0.9948	0.0000
April	0.0080	0.0000	1.0435	0.0000
May	0.0084	0.0000	1.0898	0.0000
June	0.0069	0.9968	0.0000	0.2610
July	0.0212	0.0000	1.0093	0.2523
August	0.0255	0.0000	0.9963	0.2620
September	0.0168	0.0000	0.9894	0.2878
October	0.0097	0.0000	0.9880	0.2508
November	0.0018	0.9605	0.0000	0.3910
December	0.0015	0.9536	0.0000	0.3607

The values of the constants for different months are different. The Monsoon Wetness Index for the catchment area is taken from Isohyetal map of Nepal.

4.6.3.2   MIP Method

The MIP method presents a technique for estimating the distribution of monthly flows throughout a year for ungauged locations. For application to ungauged sites, it is necessary to obtain one flow measurement in the low flow period from November to April.

In MIP Method, Nepal has been divided into seven Zones. Once the catchment area of the scheme, one flow measurement in the low flow period and the hydrological zone is identified, long-term average monthly flows can be determined by multiplying the unit hydrograph (of concerned region) with the measured catchment area.

Hydrological zone can be identified based on the location of the scheme in the hydrological zoned map of Nepal.

For catchment area less than 100 km², MIP method is used for better results,

If the measured date is on 15^th of the particular month, the coefficient given in the table is directly used. For other date measurement, coefficient for that date is found by interpolation.

 

April flow = * Measured discharge

 

Monthly flow =April flow × Monthly coefficient

 

 

 

                      Fig 6: Ecological Map of Nepal showing MIP regions

 

 

 

 

 

 

 

 

 

 

 

     Table 5: MIP non dimensional regional hydrograph coefficients

Month/Region	1	2	3	4	5	6	7
Jan	2.4	2.24	2.71	2.59	2.42	2.03	3.3
Feb	1.8	1.7	1.88	1.88	1.82	1.62	2.2
Mar	1.3	1.33	1.38	1.38	1.36	1.27	1.4
Apr	1	1	1	1	1	1	1
May	2.6	1.21	1.88	2.19	0.91	2.57	3.5
Jun	6	7.27	3.13	3.75	2.73	6.08	6
Jul	14.5	18.18	13.54	6.89	11.21	24.32	14
Aug	25	27.27	25	27.27	13.94	33.78	35
Sept	16.5	20.91	20.83	20.91	10	27.03	24
Oct	8	9.09	10.42	6.89	6.52	6.08	12
Nov	4.1	3.94	5	5	4.55	3.38	7.5
Dec	3.1	3.03	3.75	3.44	3.33	2.57	5

 

4.7        Flood Flow Analysis

In hydropower projects, high floods are required to be computed for designing the headwork structures as well as the powerhouse complex. Flood hydrology is analysed in two parts – design floods for the design of headworks and other hydraulic structures and construction floods for diversion of flood during construction period.

Finding out of the design flood in different return period are very important for the evaluation and design of any water resource projects such as design of hydropower, design of culverts and bridges, etc. The flood flow analysis is carried out to obtain the worst flood that can occur during the 100 years time so that we can design the structures accordingly for their safety and safety of the whole project.

4.7.1      Importance of Flood Flow Analysis

The flood flow analysis is of supreme importance as failure to predict the flood flow correctly may cause the immature demise of the whole project due to unforeseen flood. Reliable flood estimates are essential as the viability of a project depends on the economy of hydraulic structures. 

4.7.2      Method for Flood Flow Analysis

For Ungauged Basin:

1.Regional Methods

•      WECS/DHM

•      Rational Method

2.Empirical Method

•      Snyder‟s Method

•      B. D. Richard‟s Method

•      Modified Dicken‟s Method

•      Fuller Method

 

For Gauged Basin 

•      Gumbel Method

 

4.7.2.1     For Ungauged basins

4.7.2.1.1 Regional Methods

 

Regional formulae are based on statistical correlation of the observed peak and important catchment properties. They are made by the Departments or organizations based on the data of area of catchment, slope, coefficients of land cover etc. These formulae are best exemplified on the hydrologically homogenous areas or catchments.

 Below are some of the rational methods used to compute the flood flow :

 

4.7.2.1.1.1     WECS/DHM method (Water and Energy Commission Secretariats)

 

The WECS/DHM method (WECS/DHM, 1990) may be used for flood prediction for small hydropower project located in unguaged basins of Nepal. Using this method, 2-year (medium flood) and 100-year floods for maximum daily and maximum instantaneous flood peaks shall be computed from regression equations of the form

Where -the discharge in m³/s,

Subscriptly or an instantaneous flood peak, subscript  is either a 2 year or a 100 year return period.

.

= 14.63 for 100 year

or 2 year

= 0.7342 for 100 year

A₃₀₀₀= Basin area km² below 3000 m elevation

For other return periods 

Q_T= exp(lnQ₂+S)

Where,

Q_T= Other flood for T year return period m³/s

 

S=standard normal variate,

 

4.7.2.1.1.2     Rational Method

Rational method is commonly used method for computing peak discharge for small basins. The idea behind this method is that if a rainfall of intensity „i‟ begins instantaneously and continues indefinitely, the rate of runoff will increase until the time of concentration (t_c), when all of the basin is contributing to flow at the outlet. After t_c, runoff becomes constant for the period of rainfall excess (t- t_c). Rational method is useful for small catchments upto 50 sq. km.

 

The peak discharge is given by:

 

Q_p= (CiA)/3.6

 

Where

Q_p= Peak flood discharge (m³/s)       

C = Co efficient of Runoff (value ranges in between 0 and 1)

i = Intensity of rainfall (in mm/hr)

A =Area of catchment (in km²)

 

Assumptions:

-The computed peak rate of runoff at the outlet point is a function of the average rainfall rate     during t_c.

- t_cemployed is the time for runoff to become established and flow from the most remote part of the basin to the outlet.

-Rainfall intensity is constant throughout the storm duration. 

 

Table 6: The value of coefficient of runoff

 

Types of basin	C
Rocky and permeable	0.8 – 1.0
Slightly impermeable, bare	0.6 – 0.8
Cultivated or covered with vegetation	0.4 – 0.6
Cultivated absorbent soil	0.3 – 0.4
Sandy soil	0.2 – 0.3
Heavy forest	0.1 – 0.3

 

 

 

 

                                   Fig 7: IDF curve of several locations of Nepal

 

 

4.7.2.1.2 Empirical Methods

 

Empirical formulae shall be used only when a more accurate method for flood prediction cannot be applied because of lack of data. For flood prediction in ungauged basins of Nepal, the empirical formulae discussed in the following sections may be used with great caution and proper justification. Empirical formulae can be epitomized as   Q_p=f(A) 

Below are some of the empirical methods used for the computation of flood flow:

4.7.2.1.2.1     Snyder’s Method

Snyder‟s method was used for flood flow estimation by deriving a synthetic unit hydrograph based on known physical characteristics of the basin. In this method, the peak discharge Q_PR, in m3/s, was computed as

Q_PR=q_PR*C_A*AR

where q_PR is the peak discharge per square km of the drainage area due to 1 cm of effective rainfall for rainfall duration of t_r in m³/s/sq. km., C_A is an aerial reduction factor that accounts for the fact that the average rainfall intensity over a large area is smaller than that over a small area, R is the rainfall in cm for duration t_R derived from the 24-hour rainfall with the reduction for area. For use q_PRshall be computed from the relation

q_PR=2.78*

Where C_P is a coefficient depending upon basin characteristics and t_PR is the lag time in hours for rainfall duration t_R, calculated as

t_PR=tPR+0.25*(t_R-t_r)

In the above equation, t_r is the standard duration of effective rainfall in hours given by

T_r=

And t_pr is the lag time from the midpoint of effective rainfall of duration t_r to the peak of a unit hydrograph in hours, computed as

t_PR=0.75C_t*(LLc)^0.3

Where C_t is a coefficient depending upon basin characteristics, L is the length of stream from the station to the upstream limit of the drainage area in km and L_c is the distance along the main stream from the basin outlet to a point on the stream which is nearest to the centroid of the basin in km. The coefficients C_t and C_P shall be determined from analysis of some known hydrographs in the region. In the absence of hydrographs, the values of C_t and C_P may be adopted as 1.5 and 0.62, respectively.

4.7.2.1.2.2     B.D. Richard’s Method

B. D. Richard‟s method was used for flood estimation using rainfall and basin characteristics. The method consists of computing the flood discharge Q in m³/s using the equation. Q = 0.222AIF Where A is basin area in sq. km.,

I is the rainfall intensity corresponding to the time of concentration T_c and F is an aerial reduction factor given by

F =1.09352- 0.6628ln(A)

The value of I shall be estimated through an iterative procedure in which an initial value of T_c in hours shall be assumed and the following computations performed in sequence:

D=1.102*F
R_TC=0.22127R_TT_e^0.476577

I=

K_R=0.65I(T_e+1)

C_KR=

Te3=DCKR

T_e2=()*^1/2.17608

Where L is the basin length in km, S is the basin slope, R_T is the 24 hour rainfall for return period T in mm and T_c2 is the second estimate of the time of concentration. The iterations shall be repeated with T_c = T_c2 till the difference between the assumed T_c and the resulting second estimate T_c2 is less than 5%.

4.7.2.1.2.3     Modified Dicken’s Method

Using Dicken‟s method, the T year Flood discharge Q_T  in m³/s shall be determined as

 QT =CT A^0.7

Where A is the total basin area in km² and C_T the modified Dicken‟s constant proposed by the Irrigation Research Institute, Roorkee, India, based on frequency studies on Himalayan rivers. This constant shall be computed as            

+4

p =100(

where a is the perpetual snow area in km² and T is return period in years.

4.7.2.1.2.4     Fuller’s Method

Although developed for basins in the United States of America, Fuller‟s may be used to estimate food discharges in the ungauged basins of Nepal for comparisons purposes. Using this method, the maximum instantaneous flood discharge Q_max in m³/s shall be estimated as :

Q

Where Q_T is the maximum 24 hour flood with frequency once in T years in m³/s and A is the basin area in sq. km. Q_T shall be given by :

Q_T = Q_av

In which Q_av is the yearly average 24 hour flood over a number of years , in m³/s ,given by

Qav=CfA^0.8Where C_fis Fuller‟s coefficient varying between 0.18 to 1.88. For Nepal, C_f may be taken as the average of those values, i.e. equal to 1.03 .

4.7.2.2   For Gauged River Basin (GRB):

 

4.7.2.2.1.1     Gumbel’s Method:

This extreme value distribution was introduced by Gumbel (1914) and is commonly known as Gumbel‟s distribution. It is one of the most widely used probability- distribution functions for extreme values in hydrologic and meteorological studies for prediction of flood peaks, maximum rainfalls, maximum wind speed, etc.

Gumbel defined a flood as the largest of the 365 daily flows and the annual series of flood flows constitute a series of largest values of flows. According to his theory of extreme events, the probability of occurrence of an event equal to or larger than a value of x₀

P(X≥x₀)=1-

In which y is a dimensionless variable given by

y=a(x-a)

a=

Thus

Y=

Where = mean and _x= standard deviation of the variate X. In practice it is the value of X for a given P that is required and the eqn. is transposed as  

Y_p=-

Noting that return period T=1/P and designating Y_T= the value of y, commonly called the reduced variate, for a given T,

Y_T=-[

Y_T=-[0.834+2.303

So, the value of variate X with a return period T is 

X_T=

Where,K=

Since the MadmeKhola is not a gauged river, we could not have the provision of daily discharges of the river. So the precipitation data of the nearest rainfall station- Chame.

The values obtained from Gumbel‟s Method are fitted on the best fit line obtained from plotting position method.

4.7.3      Comparison of the flood of different method

In order to calculate the flood discharges we used several methods like – Regional methods such as WECS and Rational, empirical methods such as Snyder, B D Richards, Fuller and Modified Dickens methods. Similarly Gumbel‟s method was used to calculate the maximum rainfall for different return periods. So obtained value of maximum rainfall were used in Snyder‟s method and B. D. Richards method to calculate the flood discharges. Since the catchment area is small i.e. only 36.28 sq.km, the time of concentration is very small than the duration of rainfall. So, Gumble method gives the correct values of high flood. Therefore,

the flood discharge given by Gumble Method will be used for the design purpose which is in the higher range than the values obtained from other method fulfilling the criteria for the design purpose.

 

 

 

Table 7:Comparasion of Flood Discharge

 

 

Fig 8: Comparison Of Flood Flow Analysis

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5         PROJECT  DESCRIPTION

5.1         Project layout

 The Madme Khola Hydropower Project is a simple run-of-river scheme. The headwork site is proposed to be located in Namarjung Lower Municiplaity. This scheme diverts Madme khola  using weir through a 2130.42m long headrace canal and 490 m penstock pipe to the powerhouse. Being a medium discharge-low head project, the powerhouse will accommodate two units of Francis turbines having a total installed capacity of 3.14 MW. The water from the tailrace will be released again to Madme Khola.

5.2        Design of hydraulic structures

5.2.1         Weir and Undersluice

In order to divert the design discharge through intake, a structure (i.e. Weir) is constructed across the river to obstruct the natural flow of water and raise the water level in the upstream. With the provision of undersluice the bed loads are safely flushed to the downstream without interrupting the flow through the intake. Guide walls of concrete, masonry and rip rap is constructed in both upstream as well as downstream to protect the erosion of the banks as well as to constrict the flow of the water in the river. Also to prevent the scouring of the river bed concrete aprons along with boulder rip rap are used in upstream as well as downstream.

 

Selection of Weir Type

Among the different types of weirs, Ogee type weir is used since it has highest value of the discharge coefficient and has practical shape of water so aeration and air entrapment is prevented thus avoiding cavitation.

5.2.1.1         Design Consideration of Diversion Weir

The design of weir includes computing the elevation of weir crest, length of weir, computing the forces acting on the weir and checking the safety of the weir from all aspects like overturning, sliding, crushing etc. They all are explained in the following articles.

Elevation of Weir Crest

There are various factors that affect the elevation of the crest; since diversion of water is the purpose in this case thus the height of the weir should be sufficient to pond the water at a level that can facilitate design flow in the intake. Thus the height of the weir is governed by the height of intake sill, depth of intake orifice and depth of the river at the intake site.

The bed level of the river is 2881 masl. The crest level of the weir is provided at an elevation of 2883.6 and the crest level of the undersluice is 2881.

 

Length of the weir and Undersluice

The length of the weir depends upon the width of the waterway at the intake site. Crest length should be taken as the average wetted width during the flood. The upstream and the downstream should be properly examined for the protection consideration.

Rise in water level on the upstream of the structure after construction of the weir is called afflux. Fixation of afflux depends on the topographic and geomorphic factors. A high afflux shortens the length of the weir but increases the cost of the river training and protection works. For alluvial reaches it is generally restricted to 1m but for mountainous region it may be high. The waterway must be sufficient to pass the high flood with desired afflux. The water way is calculated by the lacey's perimeter formula:

p=4.75(Q)^0.5 for alluvial channel. But for boulder reaches it may be taken just as 60% of “p” calculated above. Minimum waterway is taken as actual width available between riverbanks.

5.2.1.2         Forces acting on weir

The main forces acting on the weir when it is in operation are: water pressure, uplift pressure, silt pressure and weight of the weir.

5.2.1.2.1      Water pressure

It is the major external force acting on the weir. This is called hydrostatic pressure force and acts perpendicular on the surface of the weir and its magnitude is given by

P=0.5xyxH²Xb

Where,

y=unit weight of water

H= depth of water

b= width of the weir surface

This pressure acts on H/3 from the base.

5.2.1.2.2      Uplift pressure

Water seeping thought the pores, cracks and fissure of the foundation material, seeping through the weir body itself and seepage from the bottom joint between the weir and its foundation exerts an uplift pressure on the base of the weir. The uplift pressure virtually reduces the downward weight of the weir hence acts against the dam stability. Uplift pressure is considered during stability analysis.

5.2.1.2.3      Silt pressure

The silt gets deposited on the upstream of the weir and exerts the horizontal and vertical pressure as exerted by the water. So flushing of the silt should be dined regularly to reduce its effect of destabilizing the weir. It is done by use of undesluice gate. The silt pressure is given by the following relation;

Psilt = 0.5*Y_sub*H*K_a

Where,

Ysub=Submerged unit weight of silt,

H=Depth of silt deposited and

Ka = Coefficient of Active earth pressure

= (1 - SinØ)/(1+ SinØ).

Ø = Angle of internal friction of silt

The silt pressure force also acts at a height of H/3 from the base.

But for practical considerations, equivalent Liquid = Mix of silt and water

Yliquid (v)= 1950kgf/m³

Yliquido(h);=1360kgf/m³

5.2.1.2.4      Weight of Weir

The weight of weir and its foundation is the major stabilizing, resisting force. While calculating the weight, the cross section is spitted into rectangle and triangle. The weight of each element along with their C.G. is determined. The resultant of all three force will represent the total weight of dam acting at the C.G. of dam, when the sectional area of each part is multiplied by unit weight of concrete weight. The weir is designed with ogee profile for spilling over its length. Hence weight is calculated by knowing its section and multiplying by its unit weight.

 

5.2.1.2.5      Protection Work for Weir Structure

The weir should be well protected from the flowing river to avoid creep effect. For this the wing wall is essential to construct. It should be well anchored into the bed. Similarly to protect the channel bed from being eroded, launching apron is used. To protect the weir body riprap is usually placed. In the site both the banks are rocky hence not any especial protection shall be introduced. Some sorts of works to protect banks and to confine the river at upstream mat be requires. Gabion walls are used as protection works for the banks which ultimately protect the degradation of the weir. In the downstream side of the spillway energy dissipater is designed to the excessive energy of the flood water. Divide wall is constructed to prevent the cross flow of the weir spillway portion and the undersluice portion. The undersluiced portion is designed as for the flood flow with limited opening of maximum 3m and energy dissipater as the submerge flow. To prevent the seepage effect, shear piles are inserted at the upstream and downstream.

 

5.3        HEADWORKS

The headworks layout has been selected considering the topography, geological conditions, space needed and flow pattern in the river. Besides, the project has been designed in consideration with efficient operation during all normal situations.

 

The headworks design of the project has been based on the following principles.

·         The structures will be able to divert necessary flow into the system

·         Bed load entry to intake is negligible and mostly passed through undersluice

 

·         Structures will be safe from any hazardous floods and excess flood in the river will be safely passed to downstream through ungated and uncontrolled free flow spillway.

·         Any floating debris will not choke the intake and will safely pass to downstream

The design basis of each of the structure of the project is discussed below.

5.4        DIVERSION WEIR

The diversion weir consists of an uncontrolled ogee shaped concrete overflow weir having a length of 8.85m. The crest level has been fixed at an elevation 2883.6masl. The head over the crest has been calculated by using the weir formula.

Q = Cx LxH^2/3

Where,

C = weir discharge coefficient and assumed 2.210 for ogee profile weir

 L = weir length in meters

H = flow depth over crest in meters

The diversion weir is designed to pass 1 in 100 years flood, which is estimated to be 46 m³/s. The flood water level for 100 years flood at the weir area has been determined assuming that the flushing gates remain closed due to operating failure. The flood level during such condition will be at 2885.124 masl.

In principle, the under sluice gates shall be fully open during monsoon period and the water head above the weir crest will be always less than that mentioned above. During the monsoon period the river transports heavy bed load, which will erode the concrete surface. Concrete surface. Therefore, hard stone lining has been proposed to prevent concrete erosion at end of ogee surface.

 

5.5        ENERGY DISSIPATION AT DOWNSTREAM

A hydraulic jump stilling basin at the downstream of the weir with a combination of

boulder lined bed is proposed for the energy dissipation. The length of the stilling basin will be 11.6 m. Boulders of size 0.2 to 0.8 m diameter have been provisioned.

5.6        UNDERSLUICE

One under sluice opening having of 1.5 wide has been designed to prevent bedload entering the intake and possible build up of the bedload in front of the intake. For controlling flow through the under sluice, one hydraulic gate has been provisioned. The under sluice has been designed with the characteristics given below:

·         Maintain a guided and uniform flow in front of the intake.

·         Enable the intake to draw desired discharge during normal flow in the river with no or insignificant suspended sediments.

·         Scour and sluice the sediment deposited in front of the intake.

·         Pass the part of the high flood during monsoon.

Maximum discharge through submerged undersluice orifice for the design flood of 100 years return period in the river has been calculated the using following relationship and the details of the calculation are given below.

Q= CxAx 2x9.81x H_max

Where,

C = Coefficient equivalent to 0.6

H = Effective head over the orifice in meter

A = Opening area in square meters

5.7         INTAKE

An orifice tvpe side intake has been designed to divert design discharge of 2.81m³/sec and 20-30% additional discharge required to flush the sediment from the gravel flushing and settling basins. In total, the design discharge for the intake will be 3.65m/sec. The intake consists of 2 orifices of size 2 m wide x 1 m high. As a coarse trash rack, a net made of iron pipe is proposed to cover the orifices so that boulder gravel of larger size will not enter through the orifices.

5.8         TRASH RACK

Trash rack shall be provided at the intake entrance to prevent the entry of any trash, such as grass, leaves, trees, bushes, timber, suspended sediments or rolling runner, boulders, which would not pass easily through the smallest opening in the turbine runner.

5.8.1        Hydraulic Design of Trash racks

The hydraulic design of trash racks shall consist of determining the shape of the

Trash rack structure, inclination of rack and geometry of rack bars.

5.8.2        Shape of Trash Rack Structure

The shape of the trash rack structure shall be chosen to meet the requirements of the head works layout and head losses. Generally, a straight trash rack structure shall be adopted for ease of construction,

5.8.3        Inclination of Racks

The inclination of racks shall be fixed based on practical consideration related to the raking operation. Except for guided racks, racks shall be installed in a slight inclination so that trash does not roll along the rack during upward raking. For manual raking, the slope shall be 1 vertical to 0.33 or 0.55 horizontal. Where mechanical raking arrangement is provided, the slope of the racks shall be kept at 10 to 15 degrees with the vertical unless otherwise specified by the manufacturer of the raking equipment

5.8.4        Rack Velocity

The velocity of flow through the rack structure shall be limited to 1 m/s for small units closely set rack bars or at intakes where raking is provided. A velocity up to 1.5 m/s shall be permitted at large units with wider spacing of rack bars and where mechanical cleaning of rack is provided a velocity of 1m/s was passed through the designed trash rack,

5.8.5        Rack Bar Geometry

From hydraulic consideration, a streamlined rounded and tapered rack bar shall be desirable. However, considering the higher cost of these bars and possibly of jamming of trash between them, simple rectangular bar type racks may normally be used, provided such bars don't result in excess head losses.

5.8.6        Losses at Trash Packs and intake openings

Head loss at intake opening should be calculated from the formula

h_r=k*(V²/2g)

 

Where,

k = entrance loss coefficient in m.

V = Velocity of flow through trash rack, computed on grosse area in m²

g= acceleration due to gravity in m/s²

 

And, the head losses at the trash rack has been computed using the following formula:

 

h_r = K* (t/b)*(V²/2g) *sin

Where,

h = loss of head through racks

t = thickness of rack bars

b = clear spacing between rack bars

V = velocity of the flow through trash rack, computed in gross area

= angle of bar inclination to the horizontal

K = factor depending on bar shape

5.8.7        Structural Design

General Arrangement

The trash racks shall generally consist of equally spaced vertical bars supported on horizontal members sitting in the grooves of piers. The size of each trash rack unit shall be proportioned from consideration of hoisting/lifting capacity.

Spacing of Trash Bars

The clear spacing of the vertical rack bar shall generaly be 5mm less than minimum opening in the turbine runner blade or wicket gates. It may vary between 10 to 100mm. In general, a close spacing shall be adopted for small turbines while a wider spacing shall be preferred for larger ones 100 mm trash bars spacing was provided in our design

The spacing of horizontal members of the trash rack lies between 400 to 500. The spacing shall ensure that the laterally unsupported length of trash rack bar does not exceed 70 times the bar thickness.

Bar Dimension

The thickness of trash bars shall not be less than 8 mm. For deep submerged racks, the minimum thickness shall be kept 12 mm. The depth of trash bar shall not be more than 12 times its thickness and nor less than 50 mm.100 mm thick bar was used in our design

 

5.9        GRAVEL TRAP

5.9.1        General

Gravel trap, as the name denotes are designed to trap gravel that enters the intake along with the diverted flow. The structure is not required if a river only carries fine sediments and not gravel (even during floods). However, most mountain rivers in Nepal carry gravel, especially during floods. In the absence of gravel trap, gravel will settle along the gentler section of headrace or in the settling basin, where it is difficult to flush out.

The following criteria should be used for design of gravel trap

·         The gravel trap should be able to trap particles larger than 2mm diameter and the velocity in the gravel trap should be limited to 0.6m/s.

.

·         If the gravel trap is hopper shaped, the floor slope should be about 30degree (1:1.7). Such an arrangement will facilitate easy flushing of gravel. If it is not possible to construct such a shape, the floor should slope towards the flushing end, with a longitudinal slope of 2-5%

·         The length of gravel trap should be at least 3 times the width of the headrace canal or 2m, whichever is larger. With this fixed length and a velocity of 6m/s. the required width of the trap can be now determined.

·         To minimize blockage of headrace or damage due to abrasion in the headrace, gravel trap should be located as close to the intake as possible.

Gravel trap can be emptied via flushing gates or by lifting stop logs (i.e. wooden planks). Since, gravel enters the intake only during the high flow, incorporating stop logs is generally more convenient and more financial.

5.9.2        Hydraulic Design

Fall velocity

The fall velocity shall be determined by:

W = (3.33*g*d*(S-1))^0.5 (Newtons equation)

Where,

             S = specific weight of particle

             d = particle size to be transported by flow

 

However, for our calculation, fall velocity (w = 0.027 m/s) has been determined using fall velocity graph presented in ITDG manual

Critical velocity

For the size of gravel to be transported by the flow in the gravel trap, the critical velocity of flow shall be determined by camp equation which is as follows.

V_cr = a (d)^0.5

Where,

               Vcr is the velocity of flow, cm/sec and in our calculation V_cr = 0.20m/s.

a = 44 for particle size greater than 1mm.

d = 0.20 mm = Particle size to be transported by flow

Area of gravel trap

 

To trap the particle size of above 2 mm diameter, the velocity in the gravel trap should be limited to 0.6 m/s.

Area of gravel trap, A = Q/V

Where,

Q = design discharge + flushing discharge = 3.65 m3/s

V = 0.6 m/s

A = 45 m²

Length of gravel trap

B = Width of gravel trap = 3 m

Thus, obtained length=5 m

Protection Work

 

Gates are used to control the flow across the gravel control the flow across the gravel trap. Flushing gates are used to flush the settled matter. The flushing orifice is controlled using the flushing gates. Flushed water and excess water are safely diverted to the river using open channel. The site protection work, fencing, etc. is carried out.

5.10   SETTLING BASIN

5.10.1    General

The suspended particles entered in a canal, if allowed to flow through the penstock pipe and turbine, cause abrasion of such units and reduce efficiency as well as durability. In addition, problem of clogging is always present due to such particles in turbine units. There is also the possibility of siltation in canals. So, the finer particles escape from gravel traps are to be removed before entering into penstock. The suspended sediments that are not settled in the gravel trap are trapped in the settling basin. The basic principle of settling is that greater the basin surface area and lower the flow velocity, the smaller particles can settle. A settling basin has significant larger cross sectional area than the headrace canal and therefore, flow velocity is lower which allows the settling of suspended materials.

A Settling basin must satisfy the following criteria:

5.10.2    Settling capacity

The length and the width of the basin must be large enough to allow a large percentage of the fine sediments to fall out of the suspension and be deposited on the bed. The sediment concentration passing the basin should be within the acceptable limits. The geometry of inlet, the width of the basin and any curvature must be such as to cause minimum turbulence, which might impair the efficiency.

5.10.3    Storage capacity

The basin should be able to store the settled particles for some time unless it is designed for continuous flushing. Continuous flushing mechanisms are however not incorporated in micro hydro schemes due to complexity of design and the scarcity of water during the low flow season. Hence, the storage capacity must be sufficiently large that a basin does not require frequent flushing.

5.10.4    Flushing Capacity

The basin should be able to be operated so as to remove the stored particles from it. This is done by opening the gates or valves and flushing the sediments along with the incoming flow in the basin. The bed gradient must be steep enough to create velocity capable of removing all the sediments during flushing.

5.10.5    Components of Settling Basin

The settling basin has three distinct zones: the inlet, settling zone and outer zones

Inlet zone

This is the initial slope where the transition from the approach canal to the settling basin occurs and is a gradual expansion in the basin and 1 in 5 slope was provided.

Settling zone

The basin reaches the required width at the beginning of this zone. Particles are settled, stored and flushed in this zone. The length of this zone is longer than the inlet or the outlet zones. It should be noted that long narrow basins perform better than short wide basins. A range of 4 to 10 is recommended for the ratio of the length to width (L/B). The length of settling basin obtained is 51.37m and width is 6.42 m of each chamber. We have used two chamber. So L/B ratio is 8 which is within the permissible limit of 4 to 10 and the length of outlet zone was found to be 4.92 m.

Outlet zone

This forms the transition from the settling zone to the headrace canal and then to the headrace canal again. The transition can be more abrupt than the inlet expansion

5.10.6    Design consideration

The settling basin is designed following standard practices. Particle approach is used to design it. Trap efficiency is selected as 90% removal of 0.2 mm sized sedimentary particles. Vetter's equation is used for efficiency calculation. Camp's equation and various charts are used to compute the transit velocity and the settling velocity.

5.10.7    Protection work

Gates are used to control the flow across the settling basin. Flushing gates are used to flush the settled matters. The flushing orifices are controlled using the flushing gates. Flushed water and the excess water are safely diverted to the river using open channel. The side protection work like fencing etc. are carried out.

5.11   Penstock

5.11.1    Pipe Material

In this study, three types of pipe material were identified as alternatives for the Pipe Material penstock and are:

·         Steel

·         Ductile iron

·         Glass reinforced plastic(GRP)

Steel pipes are locally made in Nepal. For an above ground arrangement, it provides the required durability. Additionally it is lighter than the ductile iron option and is not susceptible to vandalism as the GRP option.

Ductile iron with an internal cement mortar lining is another option for the penstock. Compared to steel, this option is suitable if the penstock has to be underground as it less vulnerable to corrosion. But it is heavier and the transportation and the installation are more onerous, hence is not considered further in this study.

The GRP pipe is relatively light and has a smoother bore. But for an above ground arrangement, it is extremely vulnerable to vandalism as it is susceptible to impact loads. Therefore steel option is selected.

5.11.2    Penstock Arrangement

The penstock starts at an elevation of 2877.5m, passes through the powerhouse and terminates at the connection to the turbine at an elevation of 2748.8 m. The penstock has 1100 mm internal diameter steel pipe. The total length of the penstock

is approximately 490 m. After placing and aligning, the sections will be welded at site.The penstock is exposed (above ground) and is supported on a series of anchor blocks and piers. Because of the topography and the landmarks, the alignment requires 6 vertical bends. In addition, vertical bends along the alignment minimize excavation and the height of the support piers.

The pipe wall thickness remains 12 mm throughout the length. Thick thickness is such that it withstands the surge pressure. The surges should be investigated further in conjunction with the electromechanically design during the detailed design phase. The penstock is provided with an expansion joint immediately below each anchor block.

5.11.3    Anchor Blocks

Anchor blocks are provided at the bends along the alignment. Additional anchor blocks are provided in straight reaches where the sectional length exceeds the maximum allowed for expansion.

The bends along the alignment is only one type that is

·         Vertical bends

·         Combined (horizontal and vertical) bends. But in our design there is no combine bend.

·         There are 6 vertical bends. The size of the anchor blocks depends on the combine bend. Angle of the bend, the hydrostatic pressure and the topography.

Anchor blocks are of concrete with 40% plums and nominal reinforcement to avoid uneven settlement & cracking. The blocks have been designed to provide stability against sliding, overturning and bearing pressure.

An anchor block is designed for most critical bend condition.

5.11.4    Support plers

The penstock pipe rests on a series of support provided uniformly in the sections between anchor blocks. To avoid overstressing the penstock pipes the spacing is maintained at not more than 6m-10m. There are 65 support piers in total.

Support piers are of stone masonry with a 1:4 cement mortar. The size and shape of the piers depend upon the topography. The piers have been designed to provide stability against sliding, overturning, and bearing pressure,

5.11.5    Expansion joints

Expansion joints are provided along alignment within the downstream side or upstream side of the anchor blocks. The expansion joints will be of sliding type.

These allow the penstock pipes between two anchor blocks to expand and contract with varying temperature.

6.14.6 Corrosion protection

To prevent corrosion, the penstock must be painted with two caps of 300um epoxy paint and single coat of zinc chrome primer.

 

 

5.12   POWER HOUSE

5.12.1    General

The Powerhouse accommodates electro-magnetic equipment such as turbine, generator, agro-processing units and control panels. The main function of building is to protect the electro-magnetic equipment from adverse weather as well as possible mishandling by unauthorized persons. The powerhouses is governed by the penstock should have adequate space such that all equipment can fit in and be accessed without difficulty. Cost can be brought down if the construction is similar to other houses in the community.

 

The generator turbines and the belt drives need to be securely fixed on the machine poundation in the powerhouse. This requires a careful design since the equipment generates dynamic force and even a slight displacement can cause excessive stress on the various parts of the equipment and lead to equipment malfunction.

5.12.2    Location of Powerhouse

The location of powerhouse is governed by the penstock alignment since the building must be located at the end of penstock. Apart from this, the following criteria are recommended for locating the powerhouse.

 

·         The powerhouse should be safe from not only annual floods but also rare flood events. Discussions should be held with the local community members to ensure that floodwaters have not reached the proposed powerhouse site within at least the past 20 years. For micro-hydro schemes of 50-100 KW it is recommended that the powerhouse be above the 50-year flood level.

·         It should be possible to discharge the tail water safely from the powerhouse back to the stream

·         If possible the powerhouse should be located on level ground to minimize excavation work

·         The proposed location should be accessible throughout the year.

·         At some place this may require constructing a new foot trail

·         The powerhouse should be located close to the community that it services, provided that the penstock alignment and other parameters are feasible and financial. This will reduce the transmission line cost, and if agro-processing units are also installed in the powerhouse, the community will not have to carry their grain for a long distance.

5.12.3    Length of machine hall

Length of machine hall depends upon the summation of length of number of units and one service/repair bay. Usually the length of 1 unit is fixed equal to the 4D+2.5 m, where D is the diameter of the turbine and 2.5 m is extra clearance provided. The estimated length of machine hall is 18 m.

5.12.4    Height of machine hall

Height of the powerhouse depends upon the height clearance from the ground to the lifting object through the crane, maximum size of plant machinery (Turbine or rotor of the generator), depth of the girder and the crane system, etc.

5.12.5    Tailrace

Tailrace is the final civil structure that coveys the design flow from powerhouse the river where it is disposed off. Open channels or pipes can be as tailrace structure. Often adequate at, such attention is not given to the design and Construction of the tailrace, probably because it does not affect power production seriously. However, such a practice can result inadequate depth of the tailrace of the tailrace pit or erosion of slopes that could threaten the powerhouse structure. The designed dimension of tailrace canal is 1.5m x 1m (BxH).

Mechanical Units

A hydropower plant requires a great deal of mechanical and electrical equipment. The major electrical components are: Shaft, bearing couple, etc for generators, oil circuits and pumps, compressors and air ducts, braking equipment. The arrangements for lighting, water supply and drainage should also be provided.

Turbine

Turbines are machines, which convert kinetic energy into mechanical energy and transmit it to the generator through direct coupling of shaft to it that it in turns converts mechanical energy into electrical energy. Based on the energy conversion, turbines are classified as Impulsive or Active and Reactive turbines.

        I.            Impulse turbine

The turbine, in which pressure head or potential energy of water is converted into kinetic energy of water in the form of jet of water issuing from one or more nozzles and hitting a series of buckets mounted on the periphery of the wheel, at atmospheric pressure is called impulsive turbine. It is used for high head and low discharge. Pelton is the example of impulse turbine.

II          Reactive turbine

The turbine, in which pressure head or potential energy of water is utilized to rotate the runner or the turbine is called the reactive turbine. The water flows through the runner under kinetic and potential energy. The turbine runner is submerged and water enters all around periphery of the runner. Water is taken up to the tailrace by means of a closed draft tube and thus whole passage of water is totally enclosed. Francis, Kaplan, Propeller, Deriaz turbine etc are the examples of reactive turbines.

Design Philosophy

There are various types of turbines with wide hydraulic features, Selection of suitable type of turbine for the project depends upon several factors like head, discharge, power production, load condition and corresponding efficiency, quality of Water, bar level size, construction feasibility, etc. Selection of turbine is essential for me layout of the powerhouse, approaching the discharge pipes, conditions construction and exploitation and techno Financial parameters.The turbine selected from following basic criteria:

1)    Head and Discharge

Medium head and low discharge          -Pelton turbine

Medium head and medium discharge   -Francis turbine

Low head and High discharge                    - Kaplan turbine

 

2)    Specific speed

 

10 to 50 - Pelton turbine

80 to 400 - Francis

300 to 500 - Kaplan (diagonal)

450 to 1200 - Kaplan (Axial)

 

 

 

Different literatures had given various charts/graphs for the selection of turbine. For medium high to medium and low heads and normal quality of water, Francis turbine is suitable. Turbine is designed based on the specific speed (Ns), which is the speed of the geometrically similar (identical in shape, blade angles, gate specific speed between 60 to 400 rpm, Francis turbine is suitable. Since, reaction turbine is susceptible to cavitation, setting of turbine is made based on the cavitation criteria. A draft tube is always provided with the reaction turbine to receive the pressure head at the outlet of the turbine. Efficiency of the Francis turbine decreases substantially at part load operation. For run off river plants, discharge of the river becomes lower than the design discharge of the plant. So, part load operation is essential. If a Francis turbine is allowed to run at part load for long time, cavitation become more serious. Thus, these criteria should be kept in mind while designing the turbine.

 

 

Figure 09: Turbine selection graph

 

Considering two turbine units with net head of 126.7 m and 2.21 m³/s  and 0.6 m³/s design flow for two diiferent unit, with respect to the turbine selection graph, the best suitable turbine is found to be of Francis Turbine. Hence, for the study Francis Turbine is adopted.

 

 

Generator

Usually in hydropower generator, armature is formed at the stator and poles are formed at the rotor. The high voltage current is tapped from the stator and connected to the transformer through the insulating cable

The stator is the steel frame of the laminate construction serving as the magnetic core and inside the slut armature winding is lad. The insulation of the stator is achieved through the resin impregnated soaked) mica paper, which can withstand manufactured in number of segments and Temperature upto 150°C. The stator is manufactured in the number of segment and installed at the site.Whole the stator rest on the concrete foundation.

 

The rotor consists of the frame of the race steel structure similar to the strut of the wheel. These radial structures are radiated from the central hub and are mounted on shaft of the generator. This assembly is called the spider The spider consist of the steel rim covering at is periphery and consist of the slots at its surface to form the poles of the rotor.

 

Rotor can be classified as:

 

1)      Thrust bearing type in this type the spider assembly is on the horizontal blade and thrust of the rotor is supported at the thrust-bearing structure located above the spider assembly.

2)      Umbrella/semi-umbrella-Umbrella type: in this case thrust of the rotor is supported on the trust bearing structure below the spider assembly, which is skewed as like the umbrella. if the spider is one the horizontal plane then is termed as the semi umbrella type.

 

Exciter

In order to create the magnetic pole at the rotor of the generator is required to feed it by direct current Providing of the field current to the rotor is termed as the excitation it could be done through the separate generator battery connected to the shaft of the turbine. After the generation of electricity, current could be taken from the main generator output through the step-down transformer. The alternate current is converted into the direct current through the Thyristor

 

Transformer

According to the power of the generator, the voltage of the generator is usually fixed

Upto 15MW. U=6.3 KW

Up to 70 MW. U=10.5 KW

And greater than that. U=18 KW

For the transmission of the power to the long distance, it is required that the voltage so as to minimize the transmission loss. For this purpose, step up is transformer provided to increase the transmission voltage at the power plant. In case of the underground power plant separate transformer gallery is provided and in case of surface powerhouse,  it is usually located outside near to the generator

Switchgear

It is the system provided at the powerhouse for the connection and breaking of the when necessary. It consists of switches. Isolators. Surge arrestor and breaker. Switches are provided at the generating voltage before transformer and the transmission voltage after the transformer. Usually, the switchgear at the generated voltage is located inside the powerhouse and for transmission Voltage located outside and termed as outside switchyards

Control room equipments

·         TV monitoring of the different location of power plant, hydraulic structures and their maneuvering

·         .Start and stoppage of the plant

·         Machine loading condition and frequency control through the governor

.

·         Generator and system voltage control

·         Machine running status

Transmission line

Energy generated at the power station has to be carried to the consumer's premises through a network of transmission and distribution lines. Transmission lines transmit bulk electrical power from sending end stations to receiving end stations without supplying any consumer's enroot Transmission system of an area is known as grid The different grids are interconnected through tie lines to form a national grid. Transmission voltages in Nepal are 33 KV, 66 KV and 132 KV and planning to transmit at 220 KV. The high voltage transmission lines transmit electrical power from the sending end sub-station (Power Station) to the receiving end stations. The transmission facilities affect the cost and reliability of energy supplied to the consumers to a great extent.

5.13   Miscellaneous Work

River training Structures

A flood protection wall along the river bank may be required if there is a high probability of flood damage to the initial headrace and other structure such as gravel trap and settling basin. Such walls are also called River Training Structures since they confine the river channel. The wall height should be greater than or at least equal to design flood level. The foundation of any river training wall must be protected from undermining by the river. This can be done by one of the following methods:

 

 

·         Founding the wall on rock or large boulders. For gabion walls, it may be necessary to first build up a level space base using stone masonry concrete.        

·         Founding the wall below possible scour depth.

·         Using a gabion mattress along the riverside o the wall. This method is not appropriate in river carrying a heavy bed load, because boulders moving during floods will damage the gabion wires.

Fencing

Various structures are to be protected from the entry of unwanted people and cattle The area is to be separated from the cultivated area, wire fencing is used in the project for this purpose.

Catch Drain

It is very important to prevent the entry of the surface and subsurface water into the various components of the project. When the structure is below the neighboring ground, there is every possibility of entry of rainwater in the structures. So, catch drain is constructed in such areas.

 

 

 

 

 

 

6         POWER OUTPUT AND ENERGY GENERATION

6.1        POWER TYPE

6.1.1        FIRM POWER

A firm power is (primary power) is the amount of power that a plant can deliver throughout a year. This power is available for more than 95% of certain time period. It is a power available when the flow of the river is minimum in run-of-river plant.  The firm power can be guaranteed to the consumer.

6.1.2        Secondary Power 

This power available   intermittently for unpredictable time, the power is called secondary power. In other words,   it is surplus or non power than the primary one and is useful in the interconnected system of power station   i.e. grid.  There is no guarantee of the secondary power and it is provided to consumer on ‘as when available’ basis.

6.1.3        Peak power

It is the power when its value is greater or equal to 4/3 of the mean or mid power.

6.2        TYPES OF HEAD

6.2.1        Gross head

It is the difference in water level elevation at the point of diversion and the point of return of water back to the river. The gross head obtained is 345 m.

6.2.2        Net Head

It is the head obtained after the deduction of losses between diversion point and axis of turbine from gross head. The net head obtained is 339.22 m.

6.3        OVERALL EFFICIENCY

Overall efficiency =Turbine efficiency * Generator efficiency

Where, Turbine efficiency =85% and generator efficiency =90%

6.3.1        INSTALLED CAPACITY

The installed capacity of a power plant is the maximum power which can be developed by all the generators of the plant at the normal head and with full flow.

 Power=9.81*2.81*126.7*0.9

           =3.14 MW

 

Table No 8: Energy Calculation Sheet

 

 

Net Head=126.7 m                                     

Design Discharge=2.81 m³/sec                  

Dry Season Outage=5%                              

Wet Energy Rate (Nrs)= 7.1

Dry Energy Rate (Nrs)= 12.4

Wet Season Outage=10%

Overall Efficiency=90%

 

 

ENERGY CALCULATION SHEET

 

 

 

                                                                                                                               Total Energy(kwh)=13109687.02

                                                                                 Grand Total  Income(Nrs)   = 102892538.7

 

 

 

 

 

 

 

 

 

 

 

 

7         COST ESTIMATES AND FINANCIAL ANALYSIS

7.1        COST ESTIMATES AND BOQ

Compressive and detailed estimate should be prepared for each structure that identify   and show the quantities of all work and supply items, such as excavation and fill, concrete etc. These estimates of quantities, grouped in pay items (B O Q), will from the basis for both the contractor to prepare their bills of payment. There are some items the cost detail of which may be difficult to estimate and hence their value is kept as lump sum (L. S.)

Based on the cost estimate and other consideration, the project cost is estimated to be 48,77,56,202, NPR which is 154,236 NPR per KW.

 

Table No: Summary Of project Cost

 

 

S.N		DESCRIPTIONS	AMOUNT (NRS)	%
	1	Infrastructures development and mobilization
	1.1	Access Road	100,000,000
	1.2	Camp facilities	20,000,000
	1.3	Water Supply and Sanitation	50,000,000
	1.4	Mobilization and Demobilization	12,000,000
	1.5	Construction Power	15,000,000
		Sub-total	197,000,000	40.39
	2	Civil works
	2.1	Site Clearance and Base preparation	15,00,000
	2.2	Earthwork in excavation for foundation in boulder mix soil (riprap)	5382395
	2.3	RCC work	7925381
	2.4	PCC work	31,220,950
	2.5	Stone soiling	10,85,175
	2.6	Bricks masonry	82,55,083
	2.7	Brick soiling	11,93,520
	2.8	Plastering	29,282,481
	2.9	protection works	1114421.56
	2.1	Wooden works	1,90,00,000
	2.11	Others	50,000
		Sub total	74975628.76	15.37
	3	Hydro-Mechanical
	3.1	Trashrack	5,00,000
	3.2	Sluice gate ( orifice,undersluice,settling basin,gravel trap)	20,00,000
	3.3	Penstock pipe (Galvanized iron)	28,583,660
		Sub -total	28,583,660	5.86
	4	Electro Mechanical works	89759475	18.40
	5	Transmissionn and interconnection system (BASE COST)	17500000	3.59

 

6	Pre- development ( 2% of the base cost)	350000	0.07
7	Land Purchse/lease (1.5 % of base cost )	262500	0.05
8	Environmental mitigation and monitoring cost ( 2 % of base cost )	350000	0.07
9	Contingency
9.1	15 % of civil work	11246344.31
9.2	10 % of hydro mechanical  work	3108366
9.3	10 % of electro mechanical works	8975947.5
9.4	10 % of transmission and interconnection system	1750000
	Subtotal	25080657.81	5.14
10	VAT ( 13 % OF CIVIL WORK)	3260485.516	0.67
11	Local TAX ( 1.5 % of base cost )	262500	0.05
12	Custom charge and duty ( 1 % of electro mechanical )	897594.75	0.18
13	Insurance ( 1.5 % of base cost )	262500	0.05
14	Engineering Administration and Management cost ( 5 % of base cost )	875000	0.18
15	TOTAL	439,420,002	90.09
16	INTEREST DURING CONSTRUCTION	48336200.2	9.91
17	TOTAL PROJECT DEVELOPMENT COST	49,63,64,051	100.00
18	COST PER KW	1,54,236

 

 

 

 

 

 

 

 

 

7.2        FINANCIAL ANALYSIS

Financial analysis is a quantitative evaluation, which presents a comparison between the benefits and cost over the lifetime of the project. The Financial analysis forms a criterion for the selection of alternatives. Again for making the decision of either constructing or not of the alternative, financial viability is one of the major criteria. The revenue earned from the project has to be assessed based on the project available energy and the anticipated rate of sales of power. These are equated against the recurring costs, which consists mainly of the interest on investment, depreciation of plant and equipment, operation and maintenance expenses, to arrive at the income surpluses. No one wants to invest for the project which will not give the good return in the future through it is feasible technically and fruitful from regional balance point of view. 

Financial analysis is made on the value of money. Analysis may be done by calculating present value of future cost or future value of present cost or in annuity. Generally, following three methods are used for financial analysis.

An investment in a small hydropower schema entails a certain number of payments, extended over the project life, and procures some revenues also distributed over the same period. The payments include a fixed component. The capital cost, insurance, taxes other than the income taxes, e t c- and a variable component. Operation and maintenance expenses- At the end of the project, in general limited by the authorization period, the residual value will usually be positive, although some administrative authorization demand the abandonment of all the facilities which revert to the state. The financial analysis compares the different possible alternative to allow the choice of the most advantage or to abandon the project from an financial viewpoint a hydropower plant differs from a conventional thermal plant, because its investment cost per KW is much higher but the operating costs are extremely low, since there is no need to pay for fuel.

The financial analysis can be made either by including the effect of the inflation or omitting it. Working in constant monetary value has the advantage of making the analysis essentially independent of the inflation rate. Value judgements are easier to make in this way because they refer to a nearby point in time which means they are presented in a currency that has a purchasing power close to present experience. If there are reasons to believe that certain factor will evolve at a different rate study, the inflation was not considered

7.2.1        Methods of Financial Evaluation 

When comparing the investments of different project the easiest method is to compare the ratio of the investment to the power installed or the ratio of the total investment to the annual energy produced for each project. Nevertheless, this criterion does not determine the profitability of the schemes because the revenues are not taken into account. But constitutes criterion. The following methods are adopted for the study.

Net Present Value (N PV) Method 

The difference between revenues and expenses, both discounted at a fixed, periodic interest rate, is the net present value (N PV) of the investment.

The formula for calculating net present Value, assuming that the case flows occur at equal time intervals and that the first cash flows occur   at the end of the first period, and subsequent cash flow occurs at the ends of subsequent periods, is as follows

 

 

 

 

V_r= residual value of the investment over its lifetime, whenever the lifetime of the equipment is greater than the assumed working life of the plant (usually due to the expiration of the legal permits).

r=periodic discount rate (if the period is a quarters, the periodic rate will be ¼ of the annual rate)

n=number of lifetime periods (years, quarters, months)

L_i= investment in period i

R_i =revenues in period i

O_i= operating costs in period i

m_i =maintenance and repair costs in period i

The calculation is usually done for a period of thirty years, because due to the discounting techniques used in this method, both revenues and expenses become negligible after a large number of years. Different project may be classified in order of decreasing N PV. Projects where N PV is negative will be rejected, since that means their discounted benefits during the lifetime of the project are insufficient to cover the initial costs.

Among projects with positive N PV, the best ones will be those with greater N PV. The N PV results are quit sensitive to the discount rate, and failure to the select the appropriate rate may alter or even reverse the efficiency ranking of project. Since changing the discount rate can change the outcome of the evaluation ,the rate used should be considered carefully for a private promoter the discount rate will be such that will allow him to choose between investing on small hydro project or keep his saving in the bank. This discount rate, depending on the inflation rate, usually varies between 5% and 12%. The method does not distinguish between a projects with high investment costs promising a certain profit, from another that produces the same profit but needs a lower investment, as both have the same N PV.

Hence a project requiring one million NRs in present value and promises one million one hundred thousand NRs profit shows the same N PV as another one with a one hundred thousand NRs investment and promises two hundred thousand   NRs profit (both in present value).Both project will show a one hundred thousand NRs N PV, but the first one requires an investment   ten times higher than the second does.

Benefit-Cost (B/C) ratio

The benefit-cost method compares the present value of the plant benefits and investment on a ratio basis. Project with a ratio of less than 1 are generally discarded. Mathematically,

 

 

 

Internal Rate of Return (IRR) Method

The internal Rate is the discount rate r, at which the present value of the periodic benefits (revenues less operating and maintenance costs) is equal to the present value of the initial investment. In other words, the method calculates the rate of return an investment is expected to yield. It can be done as

-I+(Rk-Ek)

 

The criterion for selection between different alternative is normally to choose the investment with the highest rate of return.

A process of trial and error, whereby the net cash flow is computed for various discount rates until its value is reduced to zero, usually calculates the rate of the return. Electronic spreadsheets use a series of approximations to calculate the internal rate of return.

Under certain circumstances there may be either no rate -of-return solution or multiple solutions. An example of the type of investment that gives rise to multiple solution is one characterized by a net benefit stream, which is first negative, then positive and finally negative again.

7.2.2        Result of Financial analysis

The following are considered for the financial analysis.

Project cost (Mill NPR) =4,963

O & M cost (p.a.) =1.50%

Installed Capacity (M W) =3.14

Wet season Energy (KWH) =11258034.04

Dry season Energy (KWH) =1851652.984

Wet Energy rate (NPR/KWH) = 7.1

Dry Energy rate (NPR/KWh) =12.4

Interest rate =11 %

 

Construction Distribution Schedule Year  1                        30% Year  1                        45% Year   3                        25%

 

 

Results: 

Net present Value (NPV, Mill. NPR) =323

Internal rate of return (IRR) =20.20

Benefit Cost Ratio (B/C ratio) =1.507

 

 

 

 

 

 

 

 

8         PROJECT PLANNING AND SCHEDULING

8.1        GENERAL

Project generates itself from ideas, which must be technically feasible, economically viable, politically suitable and socially acceptable. With the increasing complexity of larger projects, necessary for better planning, and scheduling is increasing. For the success any project it is necessary that the objectives and time schedules should be define with reference to attainable target into account all the problems and difficulties which may be existing at the time of drawing up of the plan or during the course of construction period. The proper planning of any project is essential to achieve the real goal.

8.2        PLANNING

Planning is general is the process of establishing project goals and the ways of achieving the goals. It is a predetermined course of action to be taken in future. Project planning is a decision planning must be systematic, flexible enough to handle unique activities. Comprehensive project planning covers the following areas.

·         Planning the project work

·         Planning the human resources and organization

·         Planning the financial resources

·         Planning the information system

Planning aims at achieving the project completion, making the most effective use of time and recourse. Project planning requires both the operational and strategic thinking and decision making. It is characterized by creativity, innovation and ability to think rationally and prospectively, project planning is a multistage process and enumerated as:

·         Establishment of objectives

·         Identify the key factors of the project

·         Identification of key Elements of projects

·         Establishing the logical sequencing of activities

·         Identification of time and resources

·         Assignment of responsibilities

·         Finalize project plan

 

For the successful run of the project, Certain development such as access road, temporary camps, facilities for drinking water, light should be provided on the project site before the actual construction starts. The construction work should be started after enough operation are lined up and definite commitments are made for arrival of material and equipments

 

8.3                PHASE OF CONSTRUCTION

In the hydropower construction, the hydropower plant construction only is not solely a project work. Before the construction of the power plant, infrastructure required for the project such as access road, bridge, temporary camps for works etc should be developed. These all works should be scheduled and proceed on phase wise. General phase of project construction can be summarized as:

·         Access road construction

·         Construction of camp

·         Construction of all civil works

·         Electromechanical works

8.4        TIME MANAGEMENT IN PROJECT

Time management simply means to get more in less time. It means utilizing minimum time to accomplish the goals. Time is scarce resource in project management. Time wastage means cost escalation.

 

8.5        PROJECT SCHEDULING 

 

The project scheduling is the done immediately after planning work is completed, approved, the budget estimate is prepared and the detailed design, tendering and the master plan is more or less finalized. The schedule of the construction works is a very important aspect of the project sa it ensures not only the timely completion of the project to comply with the energy requirements of the nation but alsoto have a tentative idea on the cash flow patterns of the project. The management of finance as will as other resources like equipments, material, and manpower for the project implementation largely depends on the schedule of construction.

While scheduling the project, the project activities are identified and their proper technological sequences and the anticipated time duration for each of the activities are estimated.

Due to the innumerable activities interdependent on another in the project, it is necessary to make the schedule in a systematic way for easy understanding and reference. The widely used techniques are;

·         Bar chart

·         Network analysis

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9          CONCLUSION AND RECOMMENDATION

 

9.1        CONCLUSION

Based on the pre-feasibility study of the Madme hydropower project, the followings are conclude:

·         The project is technically feasible.

·         The project has gross head of 128.7 meter and utilizes the design discharge of 2.81 m³/s

·         The installed capacity of the project is 3.14 MW and is capable of generating 13.10 GWh net energy annually among which 1.815 Gwh is during the dry season and 11.25 Gwh is during the wet season.

·         The project comprises two units of Francis Turbine with one for maintenance purposes

·         The project cost is estimated to be 4,963 Million NPR which results 154,236 NPR per kilowatt

·         The project is financially feasible with the dry energy rate of NPR 12.40/KWH and wet energy rate of NPR 7.10 KWH , the project financial internal rate of return of the project is 20.20% and B/C ration of 1.507

9.2        RECOMMENDATIONS 

For further analysis of the project at detailed feasibility level   , the following studies and explorations are necessary.

·         Detailed topography mapping of the headworks , penstock alignment and powerhouse area and strip survey over the headrace canal.

·         Surface geological mapping and subsurface geological   investigations should be carrier out at the headworks   , water way powerhouse area.

·         A physical hydraulic modeling of the headwork, its performance in all different flow and study of their river hydrology should be conducted to verify and validate the design.

·         Detailed Environment impact assessment has to be carried out.

·         Continuous hydrological measurements, both low flow and monsoon floods should be continued. 

·         Suspended sediment sapling shall be carried out during the monsoon period.

 

REFERENCES

·         Conveyance and Objective type Questions and Answers on Civil Engineering-R Agor

·         Engineering Hydrology – Subramanya

·         Flow in Open Channels – Subramanya

·         Guidelines to design hydropower –J. N. Nayak

·         Hydraulic structure fourth edition-P. Novak, A .L. B Moffat and R. Narayan.

·         Irrigation, Engineering and Hydraulic structure – S. K Garg

·         Irrigation, water power and water resources engineering –Dr. K. R Arora

·         Irrigation, water resources and water power- Dr. P.N. Modi

·         Water power Engineering- M.M. Dandekar