Nghiên cứu xác định dòng chảy tối thiểu nhằm quản lý bền vững tài nguyên nước vùng hạ du sông mã tt tiếng anh

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT THUY LOI UNIVERSITY LƯƠNG NGỌC CHUNG STUDY ON THE IDENTIFICATION OF THE MINIMUM FLOW FOR SUSTAINABLE

MINISTRY OF EDUCATION

AND TRAINING

MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT

THUY LOI UNIVERSITY

LƯƠNG NGỌC CHUNG

STUDY ON THE IDENTIFICATION OF THE MINIMUM FLOW FOR SUSTAINABLE WATER RESOURCES MANAGEMENT IN

DOWNSTREAM OF THE MA RIVER

Major : Water resources engineering

Code : 9-58-02-12

SUMMARY OF PHD DISSERTATION

HANOI, 2018

The product was completed in Thuy Loi University

Doctorial advisor: 1: Assoc.Prof Dr Trần Viết Ổn

2: Dr Lê Viết Sơn

INTRODUCTION

1 The neccessity of the dessertation topic

Ma River is critically important to our country, with profuse water resources, contributing significantly to the socio-economic development of the basin At the moment, the Ma river resources are being exploited and used for a variety

of purposes, which have altered the natural flow regime during the dry season resulting in negative impacts on the exploitation capacity, water use and aquatic ecosystems, especially in the downstream area of the Ma river According to monitoring data gathered at the hydrological stations, it is shown that the water level in the dry season reached a much lower level compared to the average of multiple years (0.8÷1.4m)

Changes in the flow regime on the Ma River have direct and indirect adverse effects on the water environment and ecological characteristics of the river Therefore, to balance and harmonize the river flow regime to ensure the its functions to serve socio-economic development and sustain aquatic ecosystems

of the river is very necessary On the other hand, Article 5 of Decree 120/2008/NĐ-CP on river basin management stipulates: "For each river, it is necessary to regulate, allocate water resources, maintain a minimum flow" To date, no research has quantified the amount of water needed to harmonize the demand for water between socio-economic development and ecological environment protection in the downstream of Ma River

In order to contribute to the development of a long-term strategy for the sustainable management of water resources in the lower Ma River, it is necessary to conduct a thorough and in-depth study on the scientific basis and methodology for determining the minimum flow in order (1) to meet the minimum water requirement of water users and (2) to meet the water demand to maintain the environmental flow to sustain the aquatic ecosystem in the basin river

With the above issues, the dessertation on "Study on the identification of the minimum flow for sustainable water resources management in downstream of

the Ma River" is very necessary and urgent for sustainable exploitation and management of water resources in the lower Ma River

2 Study objectives

The study objectives of this dessertation include:

- To study and develop a scientific basis for determining the minimum flow in the downstream of Ma River to meet the minimum water demand of water users and maintain the aquatic ecosystems in the downstream of the Ma river

- To study and propose solutions to maintain the minimum flow to ensure the sustainable development of water resources in the downstream of the Ma river

3 Subjects and scope of the study

3.1 Study subjects: Minimum flow in the dry season (from January to May),

downstream area of the Ma River

3.2 Scope of the study:

The Ma River Basin, (1) focuses on the lower Ma river mainstream from Cam Thuy to the estuaries, (2) in the dry season, (3) the dissertation focuses on the minimum flow requirements to serve socio-economic development (people's life, industry, agriculture, navigation) and maintain the aquatic ecosystem

In particular, at the current time, water quality in the Ma river meets the requirements of the water use purposes Therefore, in this study, water quality

is considered stable and upto the quality standards to maintain aquatic ecosystems and ensure water supply to sectors

4 Study approaches and methodologies

4.1 Study approaches: (i) Systematic approach: From From theoretical study

to to practical application, from the overall solutions to the specific solutions; (ii) Inheritance Approach: Data are inherited from previous studies and researches

4.2 Study methodologies: Inheritance method; Method of surveying,

measuring the field, sampling analysis in the laboratory; Statistical analysis method; Mathematical modeling; Comparative analysis method

5 Scientific and practical significance of the study

5.1 Scientific significance: Improve the scientific basis for the identification of

minimum flows taking into account all hydrological, hydraulic, ecological, and water demand factors for key water users Using ecological analysis methods (water environment conditions to meet the requirements of maintaining some key fish populations) is one of the important scientific contributions of the dessertation

5.2 Practical significance: The dissertation identifies the minimum flow of the

lower Ma River as a scientific and practical basis for the management of water resources on the Ma River in a sustainable manner, meeting the requirements of

the socio-economic sectors

6 New findings of the dessertation:

a Identification of the minimum flow for the downstream of the Ma River on the basis of identification and quantification of dominant factors including hydrological, hydraulic and ecological regimes, in which a ecological model based on indicator species is successfully applied

b Identification of ecological indicator species of aquatic ecosystem in the

downstream of the Ma river, including: 1) Cyprinus carpio (Chep fish), 2) Cranoglanis henrici (Nganh fish), 3) Chelon subviridis (Doi Dat fish), 4) Eleotris fusca (Bong Moi fish), và 5) Glossogobius giuris (Bong Cat Toi fish)

7 Dessertation contents: Excluding the introduction, conclusion and

recommendation parts, the dessertation include 03 chapters: Chapter 1: Overview of minimum flow and related studies; Chapter 2: Subjects and methods in studying the minimum flow; Chapter 3: Study results and

discussion

CHAPTER 1 OVERVIEW OF THE MINIMUM FLOW AND

RELATED STUDIES 1.1 Overview of the study of the minimum flow, environmental flow in river basins

1.1.1 Definitions of the minimum flow and environmental flow

Decree No 120/2008 / ND-CP dated 1 December 2008 by the Government on river basin management defines "the minimum flow as the lowest flow necessary to maintain a river or river section, ensuring the normal development

of aquatic ecosystems and ensuring the minimum level for the exploitation and use of water resources by water users according to the priority order identified

in the river basin planning” There are also many definitions of environmental flows of some organizations by the International Union for Conservation of Nature (IUCN), the World Bank (WB), International rivers, International network of global environmental flows and some authors such as Dyson, Bergkamp, Scanlon etc In general, the different definitions of "the environmental flow" share some similarities: all emphasize the maintenance of the ecosystems However, in these definitions, there is no component mentioning the flow for other water use needs and serving the socio-economic development From an overall perspective, the "minimum flow" is more comprehensive when regarding the water users and the "minimum flow" can be considered to include the environmental flow and the flow for minimum water use needs of key users Therefore, the study in this dessertation on the

"minimum flow" consists of two components: (1) ecological environmental flow, (2) flow for minimum water use needs

1.1.2 The role of the minimum flow

The environmental flow is considered to be part of the minimum flow Therefore, the role of minimum flow includes the role of a environmental flow, which is essential for the health of any river The lack of minimum flow can put the existence of ecosystems, people, and the economy at risk In the context of integrated water resources management, minimum flow requirements are a trade agreement among water users In order to facilitate the analysis of the

trade agreement, minimum flow must be ensured on the basis of equality and harmony between the interests of different users and the aquatic ecosystem

1.1.3 Overview of the minimum flow studies

2 components of the minimum flow: (1) flow for the ecological environment and (2) flow for water use demands The flow regime calculation for river basins, water balance calculations, hydrological calculations, etc., is an integral part of the study of minimum flows or environmental flows Hydrological and hydraulic models are chosen based on the purpose and content of the study and data availability In order to evaluate the flow regime in the downstream part of the river basin, it is neccesary to calculate in the long run (5 years, 10 years, 20 years or more), so studies commonly use hydraulic models for simulation, calculation and evaluation There are many models that can be used for calculating the flow regime in the downstream in the dry season such as VRSARP, HEC-RAS, MIKE11 models and other models In the three models

of VRSARP, HEC-RAS, MIKE11, each has different advantages and disadvantages, but the MIKE 11 model is one of the most widely used models

in Vietnam and the dessertatopm selects this model to calculation of flow regime in the downstream Ma river

In the world, the studies of environmental flows have grown steadily since the 1990s when a number of important studies emerged, focusing on natural flow regime and restoration of the flow The main methods are as follows: (1) Hydrological methods: Low and high flows will depend on the time and period, used widely in the North and Central America and are considered a simple, quick and least costly method to provide information on flow level thresholds; (2) Hydraulic assessment methods, also known as habitat maintenance methods

or geometric hydraulic methods, show the relationship between depth and flow, and direct and indirect impacts of the flow to aquatic species, hydraulic methods depend much on the morphology of the river so it is not suitable for tributaries; (3) habitat simulation methods for the preservation of previously selected representative species taking into account the comprehensive linkages among hydrological, hydraulic, and biological elements; (4) General method

and expert: This method is first developed and used in Australia and South Africa, recently expanded to England This is a complex, time-consuming and costly method

Evaluating studies in the world, it can be seen that environmental flows are applied according to the requirements and depending on the characteristics of each river basin as well as the ecological characteristics of the river basin With such different requirements, the studies have approaches that are tailored to the specific requirements of each river basin Thus, the dessertation inherits similarities and provides the most appropriate approach applicable to the Ma River basin in Vietnam

In Vietnam there are a number of related studies that need to be mentioned, namely Nguyen Thi Kim Dung's proposed minimum flow of 3 components (1) river maintenance flow, (2) flow for demand ecological water, and (3) minimum flow for water users in Vu Gia - Thu Bon river; Study of Doan Thi Tuyet Nga on environmental flows on the Day River from Hat Mon to Ba Tha, including analyses of hydrological data and water quality data; study on impacts of low flow to agriculture and aquaculture in lowland areas of Ca river and Ma river by Nguyen Quang Trung

Although studies have yielded the results of environmental flow or minimum flow for river basins, due to limited ecological data, they cannot quantify the specific level of the environmental flow or minimum flow and lack practicality

1.2 Overview on the Ma River Basin

1.2.1 Introduction

Ma river basin covers an area of 28,490 km2, the mainstream is 512 km long, with large tributaries such as Chu river, Buoi river and two distributaries: Lèn river and Lach Truong river The Ma river basin is distributed in Laos and Vietnam On the territory of Vietnam, the basin area is 17,690 km2, of which the lower part is 8,503 km2 concentrated mainly in the province of Thanh Hoa This river has profuse water resources and flows across the mountainous terrain, hills, plain and coastal plain (1) The mountainous areas of the Ma River have

the potential to build integrated hydraulic facilities and hydropower cascades; (2) the midland has great potential for developing industrial crops and specialty trees; (3) coastal and delta areas cover only 8.25% of the whole basin area, but are the main economic development centers of the basin, suitable for intensive farming and aquaculture development, fisheries, industrial development and marine economic services

1.2.2 The current status of socio-economic development in Ma River Basin

The economy in the Ma River basin is shifting dramatically towards industrialization and modernization and has formed many industrial parks and economic zones such as Nghi Son economic zone, industrial zone in Thanh Hoa city By 2015, the population in the entire basin is approximately 4 million people, unevenly distributed: sparsely populated in the upland areas and densely populated in urban areas The average population density is 197 people/km2 Population is concentrated in rural areas, accounting for 90%; and 10% in the urban areas The economic structure in the basin is as follows: Agriculture - Forestry - Fishery 42.58%, Industry 27.22%, Construction - Service 30.2%

1.2.3 The current status of environment and ecology in the downstream of

Ma river basin

The survey shows that the water environment in the lower part of Ma River is good, most of the water quality indicators are within the allowable limit of A2, indicating the diluting and self-cleaning capacity of the Ma River is good In the lower part of the Ma River, 747 species under 493 genus have been identified, 218 groups of creatures including 153 species of floating plants, 232 species of vascular plants, 71 species of zooplankton, 40 species soft shell, 48 crustaceans and 203 species of fish

1.2.4 History of water resources exploitation and use in the Ma river

Water resources of the Ma River have been and will be exploited for livelihood activities of the people The exploitation of water resources has been promoted effectively, typically Cua Dat - Bai Thuong system, Hoang Khanh pump station,

Nam Song Ma pump station with an increasing amount of exploitation from

50 m3/s (before 1950), reaching at 277 m3/s at the current time

1.3 Research orientation and issues to be solved

The dissertation focuses on the following issues: (i) Assessment of current issues related to water resources exploitation on the Ma River; (ii) Identification

of specific species of aquatic ecosystems and determination of water levels and flow rates in the Ma River; (iii) Application of simulation model to calculate the flow in the downstream of Ma River to meet the water demand for socio-economic development in the basin; (iv) Proposal of the minimum flow and overall solutions to maintain minimum flow with structural diagrams as Fig 1.5

Figure 1.5: Structure of the minimum flow

1.4 Conclusion of Chapter 1:

The dissertation studies the minimum flow with two components: (1) The ecological environment flow and (2) the flow for minimum water needs of water users Determining the minimum flow in the downstream of the Ma River

is a multi-purpose problem to meet the human and ecological requirements in the context of current water conditions requires further studies on factors determining the flow of water on the Ma River, development of a methodology and tools to determine the minimum flow to ensure the sustainable development

of the river The study selects MIKE11 hydraulic model, RHYHABSIM ecological model to determine the minimum flow for downstream of Ma River

CHAPTER 2 METHODOLOGY IN STUDYING THE MINIMUM FLOW IN THE DOWNSTREAM OF THE MA RIVER

2.1 Identification of the factors determining the flow regime in the downstream of the Ma river

Ma River is currently experiencing a decline in runoff during the dry season, which has a significant impact on the exploitation and use of water resources as well as the water environment, the existence and development of the aquatic ecosystem especially in downstream areas

2.1.1 Natural factors

According to the monitoring data collected at hydromet stations in the basin from 1960 to 2015, it shows a clear increasing trend in the annual average air temperature, especially in 2001÷2010 The average temperature increase in the entire region is 1oC Increasing temperature leads to higher water evaporation, and changes in the hydrographic cycle At the same time, the demands for water increase, salinity intrusion goes further into the inland due to sea level rise, the ecological environment changes and many other impacts on human beings occur

By analyzing data measured at the stations on the Ma River, it shows that the rainfall on the Ma River is following an unclear trend and no clear pattern:

- Dry-season rainfall: in the upstream tends to increase and in the downstream tends to decrease Dry-season rainfall declined in the 1960s, 1990s; increased in the 70s, 80s and increasing and decreasing trends alternated each other between the decades

- Rainy-season rainfall: The rainy season lasts from May to October; in the upstream of Ma River in the Northwest area, the rainy season finishes earlier from May to September Analyses of rainfall in the rainy seasons at some representative station in the Ma River show that the trend of rainfall in the rainy season at the representative stations tend to decrease

2.1.2 Factors from socio-economic activities

Due to the advantages of topography and water resources, currently on the Ma river mainstream over 10 medium and large hydro power plants have been built,

in addition many hydropower projects with the capacity under 10MW on the tributaries Major projects such as Cua Dat, Trung Son and Hua Na are multi-purpose projects The remaining hydroelectric projects are mainly based on the head of the water column and the basic flow for electricity generation Under the current power consumption conditions, the development of hydropower systems contributes a significant amount of electricity to the national grid If well managed, hydropower is a great resource contributing to the overall socio-economic development of the country However, these works also have impacts such as: (i) loss of watershed; (ii) Changes in the flow regime of hydropower plants; (iii) Since many hydropower projects use pressure piping to drain water from the reservoir to the hydroelectric plant, the river section from the dam to the plant becomes the dead river section without water

2.1.3 Changes in the water use demand in the river basin

Generally, in the last 10 years, in the Ma river basin, many developments in economics sectors have occured, posing higher demand for water On average, the demand for water increases by about 85 million m3 per year (about 3%/year) The total demand for water in the Ma river basin in 2015 is 3.96 billion m3, increasing by 1.27 billion m3 compared to the number for 2000 Water demand in agricultural productions is 3.6 billion m3 (accounting for 92%), domestic use is 226.8 million m3 (6%) and industrial activities 128 million m3 (4%)

2.1.4 Changes in the riverbed

Results from the research by Nguyễn Thanh Hùng, using data on the riverbed measured in 2008, 2011, 2012 và 2013 show that:

Figure 2.5: Changes in the riverbed elevation across the Ma River

from 2008 - 2013

- The Ma River from Cam Thuy to Hau has a downward trend, with a common lowering level reaching over 1m, some river beds are lowered to over 3m, especially at the bottom elevation The river is lowered to 5,08m

- On the Chu river, the level of erosion lowered the river bed from the Bai Dai dam to the Giang intersection; the erosion was highest in the upper part of Giang Giang junction, from 1.69 to 3.33m Many locations have a tendency of accretion

2.1.5 Effects of the factors

The analysis shows that changes in the flow regime on the Ma River before the operation of reservoirs (1980÷2009) and after the operation (2010÷2015) are as follows:

- In Chu river, at Cua Dat hydrological station, due to the influence of the regulation of Hua Na and Cua Dat reservoirs leading to higher fluctuation in the smallest daily flow rate and the smallest daily water level, from 3÷5m3/s, in the period before the smallest lake at the station is about 20m3/s

+ On Ma river (in Ly Nhan): Average water level and min water level in 2010÷2015 period, are lower than in the period of 1980÷2009 from 0.9÷1.0m Meanwhile, the average daily water level and the upstream water level (in Cam Thuy) in the period 2010÷2015 are higher than in the period 1980÷2009 and the