Optimal reservoir operation for water supply in dry season

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT THUYLOI UNIVERSITY ************** OPTIMAL RESERVOIR OPERATION FOR WATER SUPPLY IN DRY SEASON: THE CA

MINISTRY OF EDUCATION AND

TRAINING

MINISTRY OF AGRICULTURE AND

RURAL DEVELOPMENT THUYLOI UNIVERSITY

**************

OPTIMAL RESERVOIR OPERATION FOR WATER

SUPPLY IN DRY SEASON: THE CASE STUDY OF CUA DAT

RESERVOIR IN THE CHU-MA RIVER SYSTEM

THANH HOA PROVINCE

TRINH XUAN MANH

MSc Thesis

December 2014

Optimal reservoir operation for water supply in dry season: the case study of Cua Dat Reservoir in the Chu – Ma river system

Thanh Hoa province

Master of science thesis

This research is finished for the partial fulfillment of requirements for the Master of science

degree at Thuy Loi University, Ha Noi, Vietnam

DECLARATION

I hereby certify that the work which is being presented in this thesis

entitled, “Optimal reservoir operation in dry season: the case study of Cua Dat Reservoir in the Ma-Chu River system, Thanh Hoa province” in partial

fulfillment of the requirement for the award of the Mater of Science on Integrated Water Resource Management, is an authentic record of my own work carried out under supervision of Dr Nguyen Mai Dang

The matter embodied in this thesis has not been submitted by me for the award of any other degree or diploma

Date: … /12/2014

Abstract

Water supply of reservoirs and especially reservoirs used for irrigation, hydropower, aquaculture, navigation, environment…in the dry season are often troubled due to increasing water demands according to the economic development and society, while the flow to the reservoir is limited In recent years, the depletion of the river flow during the dry season occurs more frequently and at a more intense level This is partly due to forest coverage reduction in the upstream of river basins, and partly due to the effects of climate change

Hence, computation of the optimum water supply of reservoir for the water demands in the dry season is needed This study presents the initial research on applying Fuzzy Logic Algorithm for optimal operation of water supply in the dry season of 2011-2012 of the Cua Dat Reservoir in the Chu River basin, Thanh Hoa province The Cua Dat Reservoir is a multi-purpose reservoir for the following tasks: flood prevention, water supply, irrigation, power generation, and environmental flows

In addition, MIKE 11 model is also used to simulate the release from the reservoir to the downstream to evaluate the efficiency of the optimal method

The research used Fuzzy Logic algorithm based on the rule, the principle of "IF

- THEN" and built the membership functions for the input variables: water level, inflow to the reservoir, the water demands, and discharge from the reservoir It is developed for the Fuzzy operating systems for the Cua Dat Reservoir and is meant to determine the optimal discharge process in case of shortage of water in the dry season Inflows, releases and water levels of the Cua Dat Reservoir were collected from actual operation of the reservoir For water demand of stakeholders, the author determined that the total water demand for whole area was about 4547 Mi.m3 For hydropower based energy production water is used at the largest rate (67% of total water demand), while domestic purposes water is obtained smallest rate of water use of the Cua Dat Reservoir

Finally, the results from optimal method, the reservoir can meet 80% of water demand more than actual release throughout the dry season of 2011-2012 The initial research has been successful and the results showed that this method can be applied well to the optimal reservoir operation in Vietnam

Key words: Cua Dat, reservoir operation, optimization, Fuzzy Logic, water

demand, Fuzzy rule, MIKE 11 model

Acknowledgement

First of all, I would like to give a big thank to all people who have supported and assisted me during the Master Thesis Research Thanks for their support, encouragement and guidance that allowed me to complete this study in time

Especially, I would like to express my appreciation to Dr Nguyen Mai Dang,

my supervisor, for his unlimited encouragement, guidance, comments and technical supports on the Fuzzy Logic approach and other models as well as the thesis writing process from the beginning of the thesis research

I would like to thank NICHE-VNM-106 project from the Government of the Netherlands for their financial support during the MSc study in the ThuyLoi University I thank to Mrs Hoang Nguyet Minh and Mrs Vu Thi Thuy Ngan who made a linkage between me and NICHE I also would like to thank Assoc Prof Dr Nguyen Thu Hien, Dean of the Faculty of Water Resources Engineering, for her help and comments during the Master study in the ThuyLoi University

I wish to thank Dr Ilyas Masih and Ms Martine Rutten for their feedback, references and support from the proposal process

I also wish to thank Mrs Mariette Van Tilburg, my English teacher, for her comments and support from the final thesis report

I also want to thank the ThuyLoi University (TLU), Song Chu Irrigation Company, National center for Hydro-Meteorological Service (HMS) for providing me very useful data sets

Thanks to all of my colleagues at the HaNoi University of Natural Resources and Environment in Vietnam for your assistance in the last two years You will always

be in my mind

Last but not least, I want to take this opportunity to show my appreciation to my family, my close friends for their inspiration and support throughout my life; this research is simply impossible without you

Table of Contents

CHAPTER I: INTRODUCTION 1

I.1 Background 1

I.2 Problem statement 2

I.3 Objectives and Research questions 3

I.3.1 Objectives of the study 3

I.3.2 Research Questions 3

I.4 Structure of the thesis 3

CHAPTER II: LITERATURE REVIEW 5

II.1 Studies on reservoir operation using optimal theory 5

II.2 Fuzzy logic theory 8

II.3 Overview of hydraulic and hydrological modeling 9

II.4 MIKE model 11

CHAPTER III: THE STUDY AREA 13

III.1 Description of the study area 13

III.1.1 Location of the study area 13

III.1.2 River network 14

III.1.3 Topographical characteristics 16

III.1.4 Geological, land and vegetable characteristics 18

III.2 Climate and hydrological condition 18

III.2.1 Climate condition 18

III.2.2 Hydrological condition 23

III.3 Population and economic characteristics 23

III.3.1 Population of the study area 23

III.3.2 Economic characteristics 24

III.4 Description of the Cua Dat Reservoir 24

CHAPTER IV: DATA AND METHODOLOGY 29

IV.1 Data collection 29

IV.1.1 Meteorological data 30

IV.1.2 Hydrological data 32

IV.1.3 Cua Dat reservoir operation data 34

IV.1.4 Determining total water demand 35

IV.2 Optimal analysis and Fuzzy logic approach for Reservoir operation 50

IV.2.1 Methods using in optimal reservoir operation 50

IV.2.2 Objective functions and constraints 53

IV.2.3 Using Fuzzy logic technique to optimize the Cua Dat reservoir operation54 IV.3 Hydraulic and hydrological model setup 62

IV.3.1 Determination of the model inputs 62

IV.3.2 Model setup 63

IV.3.3 Model calibration and validation 65

CHAPTER V: RESULTS AND DISCUSSIONS 73

V.1 Optimizing the Cua Dat reservoir operation 73

V.2 Routing the release to the downstream 74

CHAPTER VI: CONCLUSIONS AND RECOMMENDATIONS 77

VI.1 Conclusions 77

VI.2 Recommendations 78

REFERENCES 80

APPENDICES i

List of Figures

Figure 2-1: Relationship between the various representations of a model 10

Figure 3-1: Location of study in the Thanh Hoa province in Viet Nam 13

Figure 3-2: Ma – Chu River Network in Viet Nam 16

Figure 3-3: Digital Elevation Model (DEM) of Thanh Hoa province 17

Figure 3-4: The location of the Cua Dat Reservoir on Ma-Chu river system 26

Figure 3-5: The main dam of the Cua Dat Reservoir 28

Figure 3-6: The spillway of the Cua Dat Reservoir 28

Figure 3-7: The storage of the Cua Dat Reservoir 28

Figure 3-8: The intake tower of the Cua Dat Reservoir 28

Figure 3-9: The gate of spillway of the Cua Dat Reservoir 28

Figure 3-10: The Bai Thuong weir 28

Figure 4-1: Distribution of monthly rainfall pattern at Thanh Hoa station 30

Figure 4-2: Distribution of monthly air temperature at Thanh Hoa station 31 Figure 4-3: Distribution of monthly average evaporation at Thanh Hoa station in 2011 & 2012 31

Figure 4-4: Distribution of relative humidity at Thanh Hoa station in 2011 & 2012 32

Figure 4-5: Annual discharge of the Cam Thuy and Cua Dat station 33

Figure 4-6: Schematization of hydrological station network 34

Figure 4-7: Monthly average discharge of Turbin of hydropower plant in years of 2011, 2012 and 2013 35

Figure 4-8: Inflow discharge of the Cua Dat reservoir in 2011 and 2012 35

Figure 4-9: Seasonal period and chart of water requirement of Spring paddy in 2011 39 Figure 4-10: Seasonal period and chart of water requirement of winter paddy in 2011 .41

Figure 4-11: Seasonal period and chart of water requirement of sugar cane in 2011 42

Figure 4-12: Water use structure of whole downstream area of the Cua Dat reservoir in 2011 48

Figure 4-13: General flow chart of optimal reservoir operation in dry season 52

Figure 4-14: Fuzzy inference system for Fuzzy Mamdani 56

Figure 4-15: Transformation of input variable to membership value 57

Figure 4-16: Membership function for reservoir level for Fuzzy Mamdani model 58

Figure 4-17: Membership function for inflow for Fuzzy Mamdani model 58

Figure 4-18: Membership function for water demand for Fuzzy Mamdani model 59

Figure 4-19: Membership function for release for Fuzzy Mamdani model 59

Figure 4-20: Fuzzy rules base for operation of Cua Dat reservoir 60

Figure 4-21: Process of application, implication and aggregation 61

Figure 4-22: Hydraulic network of the Ma – Chu river basin 65

Figure 4-23: Observed and simulated hydrograph at Cua Dat station in 2006 67

Figure 4-24: Observed and simulated hydrograph at Cua Dat station in 2008 68

Figure 4-25: Observed and simulated hydrograph of water level at Ly Nhan Station in 2006 69

Figure 4-26: Observed and simulated hydrograph of water level at Xuan Khanh Station in 2006 69

Figure 4-27: Observed and simulated hydrograph of water level at Giang Station in 2006 70

Figure 4-28: Observed and simulated hydrograph of water level at Ly Nhan Station in 2008 71

Figure 4-29: Observed and simulated hydrograph of water level at Xuan Khanh Station in 2006 71

Figure 4-30: Observed and simulated hydrograph of water level at Giang Station in 2006 72

Figure 4-31: Structure of fuzzy system for Cua Dat reservoir 73

Figure 4-32: Comparison of water demand and fuzzy and actual releases 74

Figure 5-1: Hydrograph of optimal operation at the Bai Thuong weir 75

Figure 5-2: Hydrograph of optimal operation at the Xuan Khanh station 75

Figure 5-3: Hydrograph of optimal operation at the Giang station 76

List of Tables Table 3-1: Distribution of natural areas according to provincial border of the Ma river

basin (ha) 14

Table 3-2: Characteristics of river shape of some large tributaries 15

Table 3-3: Average annual rainfall for many years at some stations of the Ma river basin 19

Table 3-4: Annual rainfall characteristics 20

Table 3-5: Monthly and annual wind speed at some stations of the Ma river basin (m/s) .21

Table 3-6: Average monthly temperature for many years at some stations 22

Table 3-7: Monthly average evaporation of some stations of the Ma River Basin 22

Table 3-8: Some main parameters of the Cua Dat Reservoir 25

Table 4-1: Kinds of data have been used in the study 29

Table 4-2: Crop distribution of different cultivated area in downstream of the Cua Dat reservoir 36

Table 4-3: Plant coefficients of paddy 39

Table 4-4: Plant coefficients of other plants 39

Table 4-5: Water requirement of Spring paddy in 2011 40

Table 4-6: Water requirement of winter paddy in 2011 41

Table 4-7: Water requirement of sugar cane in 2011 42

Table 4-8: Monthly water demand of agriculture of whole area in the Cua Dat reservoir downstream in 2011 44

Table 4-9: Water demand of industrial production at downstream of the Cua Dat reservoir 45

Table 4-10: Domestic water demand of downstream area 46

Table 4-11: Structure of water use of whole area in 2011 48

Table 4-12: Water demands and inflows in ten-day period in 2011 49

Table 4-13: List of tributary basin on the Ma – Chu river basin 64

Table 4-14: Results of MIKE 11HD model calibration at Ma-Chu river basin in 2006 .70

Table 4-15: Results of MIKE 11HD model validation at the Ma-Chu river basin in 2008 72

Table 4-16: The NASH for calculation of alternatives 74

Table 5-1: Flow characteristics at the Chu River downstream using optimal operation .76

CHAPTER I INTRODUCTION

I.1 Background

Reservoirs play an important role in the development of many countries Nowadays, there are many reservoirs and dams which were built in many developing countries for various purposes, for example, water supply, flood control, electric generation, environment and recreation…However, in 18th Century reservoirs were built to supply water, flood control and navigation as the main purposes, after that reservoirs were built for hydropower generation purpose by increasing demand for energy consumption of human

As mentioned above, most of reservoirs are used for multiple-purpose All those purposes need to be satisfied but the capacity of reservoir is limited For this reason some conflicts may happen among the water users who have other interests and conflicts also may happen in reservoir itself For hydropower generation, higher storage of water is needed, on the contrary, much water should be relaesed for cultivated areas in dry season especially Besides this, there are also many other conflicts in user factors such as transportation and hydropower generation, flood control and environment…etc

Vietnam has many big river networks with nine major river basins spread along the country At present, many multi-purpose reservoirs were built to serve the socio-economic issues such as Cua Dat, Hoa Binh and Dau Tieng Reservoir etc The management and operation for many purposes are really difficult On the other hand, the operation of each reservoir is a challenge for management and operators Reservoir operation is needed to balance efficiently interests of water users and satisfy constraint systems aim to get maximum interests An optimal policy is necessary to accomplish the problem objective and rule curve is one of appropriate methods to determine operation policy of reservoir Reservoir operation policy specifies the criteria to retain

or release water in or from a reservoir at different times of the year depending upon the inflows and demands

Optimization model used the mathematical programming technique to find the best possible solution based on a specific performance function and some physical constraints Mathematical programming includes several techniques such as dynamic programming (DP), nonlinear programming (NLP), linear programming (LP), genetic

algorithms (GAs) and optimal control theory (OCT) (Hirad and Ramamurthy 2000).

Within the development of soft computing technique, optimal technique has been used in number water resources issues In this thesis, the author will use Fuzzy technique combine with hydraulic model to develop an operation policy for multi-purpose reservoir in an efficient way

I.2 Problem statement

Ma river basin is located in North-West region of Vietnam, it bordering Laos on the West The upstream basin is located in Vietnam, the middle basin is located in Laos and the downstream is located in Vietnam Accordingly, Ma river basin is an international basin The catchment area of Ma river basin is about 31.060 Km2 of which that in Vietnam is 20.190 Km2 (IWRP 2003) The Chu River is a main tributary

of the Ma River It is located in the downstream area (IWRP 2003)

Based on potential water resources of this river system, many kinds of reservoir such as single purpose and multi-purpose were built on the main river of the Ma river system The Cua Dat Reservoir is one of the biggest projects related to water resource projects in Thanh Hoa province The Cua Dat Reservoir is a multi-purpose reservoir Those purposes include as: to reduce flood peak and protect downstream area due to probability of flood of 0.6% and control water level in downstream area at Xuan Khanh station on the Chu river (under 13.71m) in high flow season; To supply discharge of 7.715 m3/s for domestic and industrial water demand; To irrigate about 86.862 ha cultivated area; To generate electricity with capacity of 97 MW; To prevent salt water intrusion lower than 1‰ at Ham Rong measured station (MARD 2013)

As mentioned above, the Cua Dat Reservoir has purposes are to supply water for some water users such as hydropower generation, agriculture, industry, domestic and environment However, in dry season the increasing water demand of water users is one of the important problems within water shortage in this river basin due to less rainfall will enhance the conflicts among all the factors In order to balance different

water interests and solve the problems which related to using water, the Cua Dat reservoir needs to optimize reservoir operation

I.3 Objectives and Research questions

I.3.1 Objectives of the study

The main objectives of this research are:

- To optimize operation of the Cua Dat Reservoir in dry season, Thanh Hoa province

by using simulation model (MIKE 11 model) and optimal model (Fuzzy Logic Technique)

- To provide management recommendations or alternatives and suggest appropriate method of operation of the Cua Dat Reservoir in the Ma – Chu river basin

I.3.2 Research Questions

1 What is Fuzzy logic theory and how to apply fuzzy logic in reservoir operation?

2 How to balance the water demand and water interests of the stakeholders in operation of the Cua Dat Reservoir?

3 What are the objective functions and constraints in operation of the Cua Dat Reservoir?

4 Does the Cua Dat Reservoir supply enough water for all of sectors in downstream area regarding to current scenarios?

I.4 Structure of the thesis

This thesis structure includes those parts as below:

Chapter 1: This chapter discusses an overview of the study, the problem statement and the objectives of the study are presented

Chapter 2: This chapter reviews several researches of optimal reservoir operation Overview of hydrological model and optimization formulation are presented MIKE 11 model also is briefly introduced in this chapter

Chapter 3: This chapter presents natural characteristic, natural conditions of the study as well as population and economic characteristics of the study Moreover, this chapter also briefly introduces characteristics of the Cua Dat Reservoir and water demand of each water user in downstream area

Chapter 4: This chapter describes all kind of data collection and data analysis which are used in this study In this chapter, the author also shows the results of data

calculation as the input of hydrological modeling and calculating water demand of each water user in the downstream area This chapter determines the objective functions and all of constraint systems in the Cua Dat reservoir as well as using optimization model

to determine optimal rule curve (standard rule curve) Hence, the author also presents MIKE 11 model set up for calibration and validation model and the results of routing flow from the Cua Dat Reservoir by MIKE 11 model in this chapter

Chapter 5: The results of optimal model and simulation model are shown in this chapter through figures and evaluation tables The chapter also analyzes the results from two models in order to achieve the objectives of the study

Chapter 6: This chapter also focuses on the main performances, conclusions and recommendations for future studies

CHAPTER II LITERATURE REVIEW

II.1 Studies on reservoir operation using optimal theory

Optimization is scientific field about best choice in some possible alternatives Optimal theory has been developed and investigated for many years over the world Optimization has been applied to a lot of fields in human life Especially, in water resource issues are used optimal theory as one of the effective tools for management and decision making Furthermore, optimization techniques have become increasingly important in management and operations of complex reservoir systems In reservoir management, a lot of researchers have developed reservoir optimal operation during the past four decades using dynamic programming (DP), linear programming (LP), nonlinear programming (NLP), etc.(Cheng et al 2008)

Rama and Sharad (2009) have developed operation policy for multi-purpose reservoir in India using Neuro – Fuzzy technique including Fuzzy Mamdani and ANFIS (Adaptive Neuro Fuzzy Interactive system) Their research determined operation policy for monsoon period and non-monsoon period of Ramganga reservoir and optimum releases against demands for domestic supply, irrigation and hydropower generation In other research, Omid et al (2008) used optimal algorithm (HBMO-Honey Bee Mating Optimization) for single and multi-purpose reservoir to minimize the total present net cost of the system and maximum possible ratio for generate electricity with installed capacity In a case study of Hirakud Reservoir in Mahanadi basin, India, D.Nagesh Kumar et al (2009) used Folded Dynamic Programming (FDP)

to develop a long -term optimal operation policies for flood control He showed that FDP is a new search technique which can take care of all difficulties of other methods

to certain extend faced

Long N.L et al (2007) presented successfully a method as a tool for optimizing operation of reservoir by using a combination of the simulation model and optimal model The authors optimized control strategies for the largest reservoir in Vietnam, Hoa Binh Reservoir, in order to neutralize the conflicts in regulating water between flood control and hydropower generation The authors also organized two main purposes in the flood season With simulation model, they used MIKE 11 to guide the

releases of the reservoir system according to the current storage level, the meteorological conditions, and the time of the year Afterward, the shuffled complex evolution (SCE) algorithm was chosen as a perfect tool for optimizing the reservoir operation Babel et al (2011) analyzed that the tradeoff between hydropower production and environmental flow requirements for the hydropower system and the impact of alternative scenarios of a hydropower system operation on energy production and natural flow regime in the La Nga river basin in Vietnam The authors used different alternative operation policies to simulate the system by the Range of Variability Approach (RVA) method Hirad and Ramamurthy (2000) showed a new composite algorithm as an alternative model to solve the problem related to the size of reservoir when operating policy of multi-reservoir systems is applied based on Pontryagin’s minimum principle

hydro-Genetic algorithms have been widely applied in optimization to solve water resources system Cheng et al (2008) used Chaos Genetic Algorithm (CGA) which based on the Chaos Optimization Algorithm (COA) and Genetic Algorithm (GA) to apply to the global optimum of the Rosenbrock function, the Schaffer function and the optimal operation of hydropower station reservoir M.Habese, Y Nagayama (2002) used Neural Network and Fuzzy System to optimize multi-purpose Dam of flood and non- flood seasons Base on their results, the fuzzy system is an effective operation system when the major objective is water use Besides that Network Fuzzy System is effective for flood control In other research, fuzzy mathematical programming was used in research of Jairaj and Vedula (2001), their study area is a three reservoir system

in the upper Cauvery river basin, south China As the results illustrated that, use of fuzzy linear programming in multi-reservoir system optimization presents a potential alternative to get the steady state solution with less efforts than classical stochastic dynamic programming (Jairaj and Vedula 2001) Panigrahi and Mujumdar (2000) also used Fuzzy Logic in their study to reservoir operation modeling, the case study of the Malaprabha irrigation reservoir in Karnataka, India

Besides that, there are many researches in reservoir operation in Vietnam They also used many optimization and simulation methods Nghia T.T (2009) used combination method between optimization and simulation model within advanced tools

such as hydraulic dynamic model MIKE 11 and optimal technique GAMS The research had three major contents as follow: i) Determining water demand of water users (such as Industry, Agriculture, Navigation and Environment); ii) Determining upstream constraints of system due to periods; iii) Propose the operation process for three reservoirs including Thac Ba, Hoa Binh, Tuyen Quang based on optimal calculation in order to ensure that multi-reservoir can supply enough water for water requirements in downstream Hung N.T et al (2010) proposed models for optimal operation of multiple purpose reservoir The research proposed three distinct alternatives including: i) Reservoir has mutual purpose for irrigation and hydropower; ii) Reservoir’s major purpose is hydropower generation and second is irrigation; iii) Reservoir has major purpose is irrigation and hydropower generation is second Based

on models of the authors were built by using Delphi programming language and applied Dynamic programming The models were applied on Dinh Binh Reservoir (Binh Dinh province) and A Vuong Reservoir (Quang Nam province) In other research, optimization and simulation method were also used in the research of Tuyen M.H (2009) for supplying water in dry season of reservoir system on Huong River basin The research combined GAMS optimization model and MIKE 11 hydraulic dynamic model to control flow in downstream The author illustrated that environmental flow is about 31,5 m3/s in location of Thao Long Weir thoughout GAMS optimal model In dry water year with probability of 90%, the reservoir system can still ensure the lowest discharge into dowstream area is 75m3/s

Finally, optimization theories have been applied in a number of water resources issues, especially in reservoir operation Fuzzy logic technique is one of the useful optimal tools for supporting reservoir operation and decision making Using optimization and simulation models in reservoir operation research are common over the world However, the Fuzzy Logic theory has been never applied in any research about reservoir operation in Vietnam That is reason in this research the Fuzzy theory will be used as an optimization tool to optimize operation policy of Cua Dat Reservoir thoughout objective function and constraints

II.2 Fuzzy logic theory

According to Rama and Sharad 2009, the Fuzzy logic is another area of artificial intelligence It has been applied successfully in different water resources applications The key content about fuzzy logic theory is that it allows for something to be partly this and partly that, rather than having to be either all this or all that The degree of

“belongingness” to a set or category can be described numerically by a membership number between 0 and 1.0 (Rama and Sharad 2009)

In fuzzy logic theory, variables are “fuzzification” through the use of Membership Function (MF) that defines the membership degree to fuzzy sets These variables are called linguistic variables A fuzzy subset A of a universe of discourse U

is characterized by a membership function μA(x) in the interval [0,1] and represents the

grade of membership in A (Rama and Sharad2009)

The fuzzy objectives and constraints are characterized by their membership functions Membership functions are curves that define how each point in the input space is mapped to a membership value (or degree of membership) between 0 and 1 It can be of different forms including triangular, trapezium, Gaussian, B-spline, sigmoid etc Membership function can be symmetrical or unsymmetrical (Rama and Sharad2009)

Fuzzy rule base system can be used as a suitable representation of simple and complex physical systems The fuzzy rule based model operates on an “IF–THEN” principle, where the “IF” is a vector of fuzzy explanatory variables or premises and

“THEN” is fuzzy consequence Fuzzy logic theory allows the user to capture uncertainties in data A fuzzy tool is available with the MATLAB software Two types

of fuzzy inference systems including: Mamdani type and Takagi Sugeno type

Fuzzy logic theory also has been used widely in modeling of reservoir operation According to Panigrahi and Mujumdar 2000 when applying fuzzy theory need to follow several steps: (a) Fuzzification of inputs, where the crisp inputs such as the inflow, reservoir storage and release, are transformed into fuzzy variables, (b) Formulation of the fuzzy rule set, based on an expert knowledge base, (c) Application

of a fuzzy operator, to obtain one number representing the premise of each rule, (d) Shaping of the consequence of the rule by implication, and (e) Defuzzification

Similarly, the Fuzzy logic will be used in this study for the Cua Dat reservoir operation And this is the initial research using the Fuzzy Logic in operating reservoir

in Vietnam

II.3 Overview of hydraulic and hydrological modeling

Any scientific field always need a developed process including monitoring data, recording and measuring data, simulation and explanation of natural phenomenon Hydrology is a science of water on the earth To understand the hydrological events can be described in laboratory by physical models Based on theory and practice, people have explained clearly the most of hydrological phenomenon such as rainfall, infiltration, evaporation, and simulated them by hydrological models (hydraulic and hydrological models)

Accordingly, hydraulic and hydrological models are tools to address the real hydrological cycle in a simplified way That kind of models are used for understanding the hydrological processes as well as making hydrological prediction if there are some water resources management and utilization activities are implemented (Tuan 2012) The models are applied several algorithms to provide a quantitative relation between the input data (e.g rainfall, meteorological data) and output (e.g runoff) The mathematical models have been developed from 19th century with the simplest rainfall-run off model by Mulvaney (1851) to more sophisticated models such as MIKE Package developed by Danish Hydraulic Institute; Soil and Water Assessment Tools (SWAT), HEC model developed by Hydraulic Engineering Center- USA; SIMONA 2D/3D hydrodynamic models by the Dept of Public Works and Delft 2D/3D by WL|DELFT HYDRAULICS Those models are used for simulation of flow, water quality and sediment transport in estuaries, rivers, irrigation system, channels and others bodies They are fundamental to integrated water management as used for planning and decision making (Tuan 2012)

The figure below shows the relationship between the various representations of

a model (Van Waveren et al 1999)

Figure 2-1: Relationship between the

various representations of a model

The conceptual model is developed on the basis of knowledge of the system and serves as the basis for a mathematical model This model may be solved either analytically or numerically The model reated is further refined into a model program and finally into a Computer Model by entering the proper input data (Van Waveren et al 1999)

Hydrological models have been used frequently in water resources planning and management such as hydrological forecasting, reservoir operation, water quality, research on flood, inundation and drought, designing irrigation system, supporting for the integrated water resources management…etc Appropriate model selection are essential for each research or project These selections should based on study objectives, considering input data and output data, expected results and solutions There are many studies on water field that using model as an effective tool to solve problems According to Piman et al (2012), the authors used HEC and SWAT models

to simulate and evaluate flow changes from hydropower development and operation in rivers: SeKong, Se San and Sepork of the Mekong basin Long et al (2007) used MIKE

11 simulation model to set up control strategies for Hoa Binh reservoir operation They concluded that this model is an effective tool for optimizing complex system Bahremand and Smedt (2007) used distributed hydrological modeling (WETSPA) and sensitivity analysis in Torysa Watershed, Slovakia to predict daily discharge value They also presented that a strategy by incorporating a model-independent parameter estimator PEST for automatic calibration and sensitivity analysis

In this study, MIKE 11 model will be selected to rout the flow, which is released from the Cua Dat Reservoir operation to the downstream area in order to evaluate or test discharge value within constraint system at control points MIKE 11 model is a

strong model This model has been applied widely in Vietnam for many projects, especially in field of water resources

II.4 MIKE model

Many kind of hydraulic models have been applied widely in water resources issues MIKE 11 model is one of hydraulic models which have used popularly in Vietnam The MIKE 11 model has been developed by DHI water and environment (Danish hydraulic institute) This model is a professional engineering software package for simulation of flow, water quality and sediment transport in estuaries, rivers, irrigation system, channels and others bodies (DHI 2011)

The study area has slope topography, short length of river and combine complex rain regime to make flood regime change complicatedly In this study, the author selects the MIKE 11 model for routing the flow on the Ma-Chu river network To apply this model for study area, the understanding of model theory plays an important role The briefly description of the model theory according to DHI user’s manual as following (Kmenl 2008):

The most commonly applied Hydro-Dynamic (HD) model is a flood management tool simulating the unsteady flows in branched and looped river networks and quasi two-dimensional flows in floodplains When using a fully dynamic wave description, MIKE 11 HD module solves the equations of conservation of continuity and momentum (the ‘Saint Venant’ equations) as bellow:

Continuity equation:

q

t

A x

∂

∂ +

∂

∂

(2-1) Momentum equation:

∂

∂+

∂

∂

A C

Q Q g x

h gA x

A Q

t

(2-2) Where:

Q: discharge (m3/s)

x: distance along flow direction (m)

g: gravity constant (m3/s)

α : momentum distribution coefficient

The MIKE 11 solution of the continuity and momentum equations is based on

an implicit finite difference scheme developed by Abbott and Ionescu (1967) The scheme is setup to address any form of the Saint Venant equations – such as: kinematic, diffusive, or dynamic The water level and flow are calculated at each time step, by solving the continuity equation and the momentum equation using a 6-point Abbot scheme with the mass equation centered on h-points and the momentum equation centered on Q-points By default, the equations are solved with 2 iterations The first iteration starts from the results of the previous time step and the second uses the centered values from the first iteration The number of iterations is user specified (DHI 2011)

Cross sections are specified in both area and longitudinal location through the user interface The water level (h points) is calculated at each cross section and at model interpolated interior points located evenly and specified by the user-entered maximum distance The flow (Q) is then calculated at points midway between neighboring h-points and at structures (DHI 2011)

The hydraulic resistance is based on the friction slope from the empirical equation, Manning’s or Chezy, with several ways of modifying the roughness to account for variations throughout the cross-sectional area (DHI 2011)

CHAPTER III THE STUDY AREA

III.1 Description of the study area

III.1.1 Location of the study area

The Ma River basin is located in the northwest region of Vietnam, on the eastern slope of the Truong Son mountain range bordering Laos on the West The upstream basin is located in Vietnam, the middle basin is located in Laos and the downstream is located in Vietnam Accordingly, the Ma River basin is an international basin and is the 4th in biggest river basins in Vietnam following The MeKong, Dong Nai and Red river basin The whole river spreads from 22037’30’’N to 20037’30’’N and 103005’10’’E to 106005’10’’E (IWRP 2003)

- The North borders on Da river basin, Boi river and Vac river basin;

- The West borders on the Mekong river basin;

- The South borders on Hieu and Muc river basin;

- The East borders on the East Sea

Figure 3-1: Location of study in the Thanh Hoa province in Vietnam

The total catchment area is about 28,490 Km2, of which area in Vietnam is 17,600 Km2 accounting for 62% of whole area and area in Laos is 10,800 Km2corresponding to 38% (IWRP 2003) The major tributaries of the Ma river system originates from the high mountains of Tuan Giao district which belongs to Lai Chau province, Vietnam The highest point of the upstream part is 1,500 m, the river flows through the area of provinces and nation, namely, Son La, Lai Chau, Hoa Binh, Laos and Thanh Hoa, and flows into the East Sea finally via three river mouths, namely Hoi, Lach Truong and Lach Sung Accordingly, Hoi river mouth is a main mouth of the Ma River The Ma River has length of 512 Km of which 102 km is located in Laos and in Viet Nam is about 410 Km

Table 3-1: Distribution of natural areas according to provincial border

of the Ma river basin (ha)

No Provincial units Natural

area

Possible agricultural soil

Possible forestry soil Geography

II Viet Nam 1.750.249 287.828 1.299.987

1 Dien Bien 209.475 19.649 188.452 High mountain

5 Thanh Hoa 823.090 194.464 588.893 High land- Delta

Total 2.849.000 320.790 2.124.050

(Source: Final engineering report of the Cua Dat Reservoir in operation period -2014)

III.1.2 River network

The Ma river flows on the Northwest – Southeast direction, the river direction is similar to tectonic direction, the length of major river is around 512 Km, originates from the highland of Tuan Giao district, flows through some of provinces, enter into Thanh Hoa province at Muong Lat, Quan Hoa location to discharge the East Sea at Hoi estuary The basin has river density of 0.66 km/km2, the meandering index is 1,7, the shape index is 0,17, the average slope of the basin is 17,6 % (IWRP 2003)

The Chu River basin is one of main tributaries of the Ma River in this river basin It is located in the downstream area The catchment of Chu River is about 7,500

km2, of which 65% are located in Laos and 95% of Chu river catchment area is in

mountains (IWRP 2003) The Chu River joins the Ma River at Giang confluence which

is about at 26 km away from Ma river mouth The river originates from Sam Nua high mountain which belongs to Laos, with elevation of 2,000 m, this river flows meanderingly in dangerous high mountains such as Phu Nam (2,050 m), Phu Bo (1,455 m), entering into Viet Nam at Nghe An province The main flow has a length of 325

Km of which 100 Km is located in Vietnam

In Vietnam’s region, the Chu River flows on narrow and slope valleys with a lot

of waterfalls There are 15 waterfalls from Muong Hinh to Cua Dat location From the confluence of the Dat River to downstream, the river networks have risen significantly, the Chu River has a protected dyke system and many large tributaries such as the Am River, the Dat River and the Dang River Among these tributaries, the Am River is a largest one

The Buoi River is a second main tributary of the Ma River This river originates from Chu Mountain which belongs to Hoa Binh Province The main river flows towards North-South direction joining the Ma River at Vinh Khang position The length of this river is about 130 km, basin area is 1,790 km2 and average slope is 1.22 The upstream of the Buoi River includes three major stream, namely Cai, Bin and Cong Hoa streams

The Cau Chay River is originated from Den Mountain flowing towards West direction though out delta of Ma River south and Chu River north The total length is about 87.5 km and basin area is 551 km2

East-The table 3-2 shows detailed characteristics of river shape in the Ma-Chu river system as below:

Table 3-2: Characteristics of river shape of some large tributaries

No River Basin F

(km2)

% of area (%)

Length (km)

Aver

elevation (m)

Aver

width km/km 2

Aver

slope (%o)

River density (km/km 2 )

matrical index

Unsym-Shape index

Mean dering index

Figure 3-2: Ma – Chu River Network in Vietnam III.1.3 Topographical characteristics

The Ma river basin spreads widely many regions between Vietnam and Laos This basin ranges from Truong Son Mountain range to Northern Bay, the topography is strongly fragmented and changing complexly The main slope directly ranges from West-North to East-South The topographical elevation varies from 1.0 m to 2000 m which can be divided into three main categories of topography, are described as below:

- High mountain terrain: This area is in the upper part of the river basin: from Ba Thuoc location to upstream of Ma River, and from Cua Dat location to upstream of Chu River The highest elevation of this topography is Phu Lan Mountain with elevation of 2,275 m The elevation changes towards North-South direction The area

of this topography is about 23,228 km2 and it takes 80% in total The forestry trees are

primary on this one Agricultural land is around 75,968 ha and accounted for 3,26% of natural area, the current area for agriculture is 51,466 ha There are many river valleys, those are advanced to construct multi-purpose- reservoirs in order to supply water for many objectives such as power generation, water supply, flood prevention and control and water environment

- Highland terrain: This area almost distributes in the districts such as Thach Thanh, Cam Thuy, Ngoc Lac, Trieu Son, Tho Xuan in the Thanh Hoa province and Tan Lac, Lac Son, Yen Thuy in Hoa Binh province The elevation of this terrain varies from 20

m to 150 m This region has a potential to develop industrial plants, special trees within cultivated area of 85,100 ha, current cultivated area is 58,100 ha On this terrain there are many streams, rivers which have potential to construct reservoirs in order to supply water for irrigation, domestic supply, flood control and environmental improvement

- Valley terrain: This terrain lies totally in the Thanh Hoa province, and it has elevation from + 1.0 - +20 m In this terrain, the deltas have been formed due to the development of river network such as Vinh Loc; South of Ma River – North of Chu River; South of Len River

Figure 3-3: Digital Elevation Model (DEM) of Thanh Hoa province

III.1.4 Geological, land and vegetable characteristics

A- Geological and land characteristics

This river basin has some geological and soil characteristics as following:

- The upstream of the Ma River, the Chu River and Buoi River are mainly sediment Sand and gravel concentrate along the rivers

Magma The middle of the Ma river basin: material construction is abundant

- The downstream has been generated by Preterozoi Nam Co stratum and Paleozoi formation developed strongly in Thanh Hoa province where Merozoi sediment is major

- The Ma River Basin has 40/60 types of soils and has formed into 11soil groups: Sandy soil; Salt soil; Acidic alum soil; Alluvial soil, Bog soil and Permafrost soil; Grey soil; Black soil; Red soil; Humus soil, Valley soil; Leachy soil

- Thanh Hoa province has 8 types including: Sandy soil; Salt soil; Alluvial soil; Grey bog soil, Black soil, Grey soil, Red soil and Leachy soil

- Among 8 soil types in Thanh Hoa province, Alluvial soil is main soil in delta and important soil to form a sustainable agriculture in local region

B- Vegetable cover characteristics

Vegetable surface on the basin is very abundant in types, categories and is formed by differentiation of climate, geography and human activities

Geography of the basin occupies an important role in forming the vegetable on this basin: high mountain terrain always has types of vegetation such as wide leaf forestry and brushwood… Highland terrain forms wide leaf forest, secondary brushwood, bamboo Delta terrain is mainly industrial trees, rice, fruit-trees…

Among categories of vegetation, type of secondary vegetation and plantation are major Natural vegetation still is existed, but little

III.2 Climate and hydrological condition

III.2.1 Climate condition

The Ma river basin spreads on two latitudes and longitudes Therefore, the climate of region varies on space The region has the tropical –monsoon climate There are four seasons in year including spring, summer, autumn and winter Climate of different regions are spatial and temporal distribution The upper area is located on

North-West pattern climate and Chu River is on Central North pattern climate The others are located on interaction area between above climates (IWRP 2003)

a) Precipitation

Precipitation of the Ma river basin has been divided into three different regions The upper part of Ma River has rain regime of Northwest region, the wet season starts early and finish early than middle region The Chu River basin lies on Central North rainy region, the wet season comes late in range of 15 – 20 days; finish late in range of

10 -15 days than Northern region

The annual average rainfall of the region varies from 1100 to 1860 mm/year The region has two seasons of rain which are dry season and wet season According to the statistical data of many years, the wet season of the Ma River upstream frequently begins from May to November and the dry season is from December to April The rainy season of Chu river basin begins frequently at the end of November to the beginning of December Total annual rainfall of two seasons is strongly disproportate The total rainfall of wet season accounts 65 – 70% of total annual rainfall, the total rainfall in dry season only accounts 30 -35% of total annual rainfall

Table 3-3: Average annual rainfall for many years at some stations

of the Ma river basin

(Source: Final engineering report of Cua Dat Reservoir in operation period -2014)

Table 3-4: Annual rainfall characteristics

No Stations Aver Max Year Min Year Max/Min

it brings much more moisture to make heavy rain The average wind speed is from 2 – 2.5 m/s This wind occurs from March to October with annual year Besides that, there

is dry and hot South- West wind in April and May It only occurs 3-4 times in year with 4 -5 days for one

Table 3-5: Monthly and annual wind speed at some stations

of the Ma river basin (m/s)

Tuan Giao 0.7 0.8 0.7 0.8 0.7 0.7 0.7 0.6 0.6 0.6 0.7 0.7 0.7 Song Ma 1.6 2.0 1.6 1.3 1.0 0.9 0.8 0.8 0.8 1.0 1.1 1.4 1.2 Hoi Xuan 1.5 1.5 1.6 1.6 1.6 1.4 1.6 1.4 1.3 1.3 1.3 1.4 1.5 Lac Son 1.2 1.5 1.4 1.6 1.4 1.1 1.2 1.0 1.1 1.2 1.1 1.2 1.2 Bai Thuong 1.3 1.5 1.3 1.4 1.3 1.2 1.3 1.2 1.3 1.3 1.3 1.2 1.3 Thanh Hoa 1.8 1.8 1.7 1.9 2.0 1.9 1.9 1.5 1.7 1.9 1.8 1.7 1.8 Nhu Xuan 1.4 1.4 1.3 1.4 1.8 1.8 1.8 1.5 1.5 1.6 1.4 1.3 1.5

Stations 1 2 3 4 5 6 7 8 9 10 11 12 Aver

Yen Dinh 1.6 1.8 1.7 1.7 1.6 1.3 1.5 1.2 1.3 1.5 1.4 1.5 1.5 Tinh Gia 1.8 1.6 1.6 1.7 2.0 2.1 2.1 1.7 1.9 2.2 2.2 1.9 1.9

(Source: Final engineering report of the Cua Dat Reservoir in operation period -2014)

c) Temperature

There are 02 regions on the Ma river basin with different temperature regime The highland, cold season starts from November to February, dry season is from March

to October The temperature of this region is similar to North- West region The delta

of Ma river, average annual temperature is higher than the highland The Winter ends early than North region form 15 – 20 days, the highest temperature is higher than highland On whole basin, average annual temperature changes from 2204 to 23.60C Average sunshine hours are range from 1,756.7 to1.896.4 hrs/year

Table 3-6: Average monthly temperature for many years at some stations

Tuan Giao 14.6 16.3 19.5 22.6 24.6 25.1 25.2 24.8 23.9 21.6 18.3 15.0 21.0

Song Ma 16.1 18.5 21.2 24.3 26.1 26.4 26.3 25.9 25.1 22.8 19.6 16.3 22.4 Hoi Xuan 16.6 18.0 20.7 24.5 26.9 27.6 27.6 27.0 25.6 23.5 20.5 17.6 23.0

Lac Son 15.9 17.3 20.2 24.0 27.2 28.0 28.3 27.6 26.3 23.7 20.4 17.3 23.0 Bai Thuong 16.5 17.5 20.1 23.9 27.0 28.2 28.4 27.6 26.6 24.3 21.2 18.0 23.3

Thanh Hoa 17.0 17.3 19.8 23.5 27.2 28.9 29.0 28.2 26.4 24.5 22.4 18.6 23.6 Nhu Xuan 16.5 11.3 20.0 23.6 27.3 28.6 28.9 27.8 26.5 24.2 20.8 17.9 23.3 Yen Dinh 16.7 17.6 20.2 23.6 27.2 28.5 28.9 28.0 26.8 24.4 21.2 18.1 23.4 Tinh Gia 16.8 17.1 19.6 23.2 27.2 28.9 29.5 28.3 26.8 24.5 21.2 18.1 23.4

(Source: Final engineering report of the Cua Dat Reservoir in operation period -2014)

d) Evaporation

Total yearly evaporation on the basin is from 872 mm to 925 mm Minimum daily average is about 1.3 mm/day, maximum is 4.6 mm/day The maximum evaporation happens in May, June and July The difference of land evaporation and water evaporation ∆Z = 230 – 250 mm/year

Table 3-7: Monthly average evaporation of some stations of the Ma River Basin

Tuan Giao 57.9 69.2 89.5 93.2 89.2 63.4 62.4 55.8 60.1 59.7 53.0 53.4 806.8

Stations 1 2 3 4 5 6 7 8 9 10 11 12 Aver

Song Ma 65.0 81.7 111.6 108.6 101.4 62.0 56.8 51.2 57.7 60.8 57.6 57.6 872.0 Hoi Xuan 87.9 104.4 141.3 133.0 129.9 90.4 78.8 62.5 63.9 68.0 67.5 75.7 1103.3 Lac Son 56.2 63.5 89.8 102.2 112.0 89.2 86.2 62.8 58.8 63.0 55.8 56.2 895.7 Bai Thuong 39.8 42.5 53.0 65.3 79.2 64.8 64.4 52.0 46.6 48.1 41.1 42.6 639.4 Thanh Hoa 48.3 44.7 49.7 65.5 91.2 79.5 81.7 59.7 56.1 60.7 55.6 56.5 749.2

Nhu Xuan 47.7 42.7 44.8 56.6 82.4 79.5 85.8 67.4 66.3 72.3 70.5 67.1 783.4

Yen Dinh 54.6 39.8 39.7 50.0 89.7 94.4 104.3 74.7 63.9 74.8 69.9 64.9 820.7 Tinh Gia 46.3 36.5 40.2 53.9 106.3 124.8 138.5 88.2 68.0 78.5 76.1 68.1 925.4

Tuan Giao 63.9 50.6 49.7 55.2 86.5 88.3 101.6 68.1 63.0 74.4 78.3 76.7 856.3 Song Ma 48.5 33.4 33.6 47.4 98.3 121.3 138.2 92.6 68.3 70.5 77.6 67.7 897.4

(Source: Final engineering report of the Cua Dat Reservoir in operation period -2014)

III.2.2 Hydrological condition

Flood season on the Ma River often happens from June to October, accounts for 73-74 percentage of total annual water Dry season is from November to May Three months which have maximum flow is July, August and September with 53 – 56 % in total while that of August has maximum flow with 20 – 30% in total On the Chu River, flood season often occurs from July to October, accounts for 52 – 60% in total The month that has maximum flow is September with 20 -24 % in total annual flow

Dry flow occurs in dry season in year The Ma River Basin has dry season which is from November to May Besides that dry season spreads 08 months, from October to June on the Chu River Basin Amount of flow in this season only takes 20 – 35% in total In general, dry season can be divided into 03 periods: First period includes 02 months (November and December), this period can be seen as middle period between 02 seasons, maximum middle dry period is from January to April in year

III.3 Population and economic characteristics

III.3.1 Population of the study area

According to the statistical yearbook 2012, the population of the Thanh Hoa province is about 3,697,227 people Highland population is 718,000 people The others

live in the delta where can be damaged by flood The natural population growth rate is 0.8 %

Due to current statistical population, there are 13 peoples who live on the Ma river basin The population of Kinh people is very popular with 80 % in total and the second is Muong people with 10%, other ethnic groups are Thai, Lo Lo, Ha Nhi, Thanh, Meo who live in high mountain region There is no border among life area of the peoples They live together forming a people community on this basin

III.3.2 Economic characteristics

Based on statistical data in year of 2007, general economic distribution of the Thanh Hoa province was as follow: Industry was 36.87 %, Service was 34.77 %, Agriculture, Forestry and Fishier was 28.36 % of GDP in year of 2007 was 25,689.3 billion VND The economic growth rate was about 10.5 %

The major economic activities were paddy rice cultivation, farming of industrial crops, trading, livestock breeding and handicraft

III.4 Description of the Cua Dat Reservoir

- Position:

The Cua Dat reservoir has been constructed on Chu River and in Xuan My Commune, Thuong Xuan District, Thanh Hoa province (Figure 3-4) This is the largest reservoir which has maximum storage on the Ma – Chu river system with total storage

of 1,364 million cubic meter Some main parameters of the Cua Dat Reservoir are shown in the table 3-8

-Main objectives of the reservoir:

This is a multi-purpose reservoir with following objectives:

- To control flood in order to protect downstream area with probability flood of 0.6 % To ensure water level of the Chu River at Xuan Khanh station (Tho Xuan district) is lower than 13.71 meter;

- Supplying domestic and industrial water with suitable discharge of 7.715 m3/s;

- Irrigating for 86,862 ha of cultivated land (Including Nam Song Chu region is 54,301 ha and Bac Song Chu – Nam Song Ma is 32,831 ha)

- Generating hydropower with installed capacity of 97 MW

- Supplying additional water in dry season with discharge of 30.42 m3/s in order

to control salt intrusion at Ham Rong Bridge (lower than 1 ‰)

Table 3-8: Some main parameters of the Cua Dat Reservoir

I Basin parameters

3 Design maximum discharge P = 0 ,1% m3/s 15,400

II Reservoir parameters

1 Surface area of the reservoir at useful water level km2 30,79

III Construction

Dam

Valve

1 Surface weir with arc valve

Hydropower Plant

No Parameters Units Values

(Source: Final engineering report of the Cua Dat Reservoir in operation period -2014)

Figure 3-4: The location of the Cua Dat Reservoir on the Ma-Chu river system

- Existing operation rule curve of the Cua Dat Reservoir:

Reservoir operation plays an important role and is one of problems related to water resources planning and management Generally, after dam construction, an operation policy has been established to help managers giving significant decisions Operation policy is determined based on water storage, water demand and all of information of inflow with current reservoir status The single purpose reservoir decides an operation policy which aimed to maximize that purpose interest The multi-purpose reservoir is optimal release allocation in order to balance interest among purposes Finally, the complex operation is based on amount of objectives and membership functions

The Cua Dat Reservoir has been operated since 2012 Annual operation policy

of this reservoir is established by Ministry of Agriculture and Rural Development (MARD) According to new operation policy during the flood season in 2013 to the beginning of flood season in 2014, included 7 main chapters with following concepts: (1) General article; (2) Regulated operation in flood season in 2013; (3) Regulated

operation in dry season in 2014; (4) Emergency operation; (5) Monitoring Meteorological – hydrological data; (6) Responsibility and Right; (7) Implementation policy According to the purpose of this thesis, the third policy is considered to be the most important The articles of third policy will be briefly described as below:

Article 9: Before the dry season in 2014, Song Chu Irrigation Company has to plan to

supply water which is based on current storage reservoir, meteo-hydrological forecast, water demand It should be reported to the Department of Agriculture and Rural Development of Thanh Hoa province, and all of water users in the system

Article 10: Regulate water level of reservoir in dry season

1- During regulated operation, the reservoir elevation must be above or equal the lower rule curve in operation policy

2- Lowest reservoir elevation at the end of every month is described as below:

TIME 31/XII 31/1 28/II 31/III 30/IV 31/V 30/VI

LWL

(m)

Article 11: When the reservoir elevation is above or equal the lowest rule curve, Song

Chu Irrigation Company must supply enough water to all of water users according to the water supply planning

Article 12: Hydropower generation schedule of the Cua Dat and Doc Cay hydropower

plant have to follow the irrigation schedule of the Cua Dat reservoir

Article 13: Operate water supply in some emergency cases

1- When the reservoir elevation is lower than lower rule curve and above inactive level, Song Chu Irrigation Company and water users need to implement water saving solutions

2- When the reservoir elevation is equal or lower than inactive level, Song Chu Irrigation Company need to plan a water supply schedule using inactive storage, then, reports the Department of Agriculture and Rural Development, Thanh Hoa province in order to make decision and implement

Some figures that the author collected after the field survey to the Cua Dat Reservoir in 2014 Those pictures present clearly constructions or parameters related to the Cua Dat Reservoir such as dam, flood valve, spillway, storage, intake tower, and weir…Those pictures are as below:

Figure 3-5: The main dam of the Cua Dat

CHAPTER IV DATA AND METHODOLOGY

IV.1 Data collection

In this thesis, the author used some kinds of data for the contents such as: Determining water demand, Optimizing reservoir operation and Numerical model The datasets were used in this study including meteorological data, hydrological data, the Cua Dat Reservoir data and some other information regarding to crops, population and industrial zones They are listed in the following table:

Table 4-1: Kinds of data were used in the study

and storage and Reservoir’s water level and surface area relation)

- Other related data

Song Chu Irrigation Company

as checking, approved by these organizers Hence it is able to have confidence into those sources The data collection plays an important role in the thesis calculation, as a foundation is to determine water demand of each crop, operate the reservoir and set the hydraulic model for study area and achieve the better output of this thesis so far

IV.1.1 Meteorological data

In the study area, there are many rainfall stations and meteorological stations These stations have been located in or close to the basin and have a long time period of observation (from 1980 to 2009) However, the author did not use all of them, it only used some of them due to data quality and location of stations

In order to define the water demand of each crop and cultivated plants, the author used the meteorological data of the Thanh Hoa station such as rainfall, evaporation, relative humidity, wind speed and sunshine hours within time interval of daily period of 02 years (2011 and 2012) Some of figures of these data are shown as following:

According to the Figure 4-1, we can see that maximum rainfall occurs in the month of September in year of 2011 and 2012 The rainfall in the month of January to May is quite small The rainfall increased significantly from June to September and it reaches a peak at September with more than 700 mm in year of 2011, more than 400 in year of 2012 Then, it decreased from October to April

Figure 4-1: Distribution of monthly rainfall pattern at Thanh Hoa station