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

LƢƠNG 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

1: Assoc.Prof. Dr. Trần Viết Ổn

Doctorial advisor:

2: Dr. Lê Viết Sơn

Reviewer 01:

Reviewer 02:

Reviewer 03:

The dissertation was defended against the dissertation review board at Room 5K1 of Water Resources University
Dated

2018.

The dissertation can be found at:
- National Library
- Library of Thuy Loi University


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
1


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,
2


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.

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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
4


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
5

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
6


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 A 2,
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,
7


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 socioeconomic 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.
8

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

9


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 multipurpose 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 socioeconomic 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:

10

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
11


flow at Cam Thuy station during the dry season also changed not much. in two
periods. This shows the clear impact of low level depression on the lower Ma
river mainstream in 2010 to 2015.
- On the Chu river (at Xuan Khanh station): The average water level and min

water level in the reservoir period (2010÷2015) are lower than before the lake
30÷50 cm, although from 2010÷2015 The dry season has been improved thanks
to the regulation of Cua Dat Lake upstream.
Impacts of low flow in the lower part of the Ma River: Saline intrusion deeper,
lowering water levels directly affecting river basins, altering ecological habitat
aquatic life
2.2. Developing the methodology to calculate the minimum flow in the
downstream of the Ma river
2.2.1. Methodology to calculate the minimum flow
The minimum flow can be considered as the “environmental flow” plus the
“demand for water uses in the calculated river sections” (at the minimum level)
QTT = ∑(QMT,ST, QKTSD)

(2-1)

In which: QKTSD: is the flow to ensure the socio-economic activities, in this
study including: water supply for domestic use, industrial production,
agricultural production and navigation. QKTSD consists of 2 components: (i)
Consumed environmental flow (Qmtth): is the flow that is exploited from the
Ma river for water supply in domestic uses, industrial and agricultural
productions; (2) Non-consumed environmental flow (Qmtkth): is the flow
which is not consumed during the exploitation, such as in navigation.
- QMT,ST: is the flow to ensure the normal operation and development of the
ecosystem and is the non-consumed environmental flow.
From the characteristics of the consumed environmental flow and nonconsumed environmental flow, the formula 2-1 is summarized as:
QTT = ∑(Qmtkth+Qmtth)

(2-2)

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In which: Qmtkth is the non-consumed environmental flow, is the total value to
ensure the development of the aqua ecosystems, river health, river landscape
and navigation. Within the scope of this study, the non-consumed
environmental flow consists of 02 parts: (1) flow for navigation and (2) flow
for the ecosystem. Therefore:
Qmtkth = ∑ (Qstts, Qgt)

(2-3)

In which: + Qstts is the the flow for the aquatic ecosystem
+ Qgt is the flow for navigation
To identify the minimum flow in the downstream of the Ma river, in this study,
the PhD candidate selected combined methods, including: (i) Field survey and
measurement methods; (ii) statistical analysis method; (iii) Hydrodynamic
modeling; (iv) ecological modeling; (v) Comparative analysis.

Figure 2.21: Steps in calculating the minimum flow
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2.2.2. Numerical modelling to simulate and calculate the flow regime
a. Method to identify the water demands at intake nodes along the river
The Ma river basin is divided into 8 water supply areas. In the upper reaches of
the Ma River to Cam Thuy, the upstream of the Chu River to Cua Dat, the
upstream of the Buoi River to Thach Quang, the water supply is mainly from
dams on small tributaries . One of the factors influencing the flow regime in the
downstream of the Ma River is the exploitation and use of water from water
supply facilities directly on Ma River, Chu River and other rivers. Therefore,

the identification of water demand for the downstream Ma River in this study
focuses on the identification of water demand at the direct water intake
locations in the river. The method is as follows: (i) Investigation and
identification of actual exploitation demand from 2010÷2015; (ii) Determining
the water demand at the downstream points of the Ma River. Under the current
conditions of water resources are seriously degraded, the water supply works in
difficult water conditions, the ability to meet the water demand of irrigation
works has also approached. minimum water requirements. Therefore, in the
dessertation, the actual volume of water extracted from 2010÷2015 is the
minimum amount of water for the water demand of the industries.
b. Modeling simulation method for flow regime calculation on the Ma river
Hydraulic models are used to calculate and simulate the flow patterns in the dry
season in the past, as a basis for analysis and determination of flow for
navigation demand, minimum flow for the environment ecological and
selective minimum flow appropriate for river sections, as well as proposed
minimum flow maintenance solutions.
The MIKE 11 model used in the study looks at all components of the wave
equation and solves the equation of momentum and momentum equations (St
Venant equations).
c. Modeling simulation method for ecological flow calculation
The study use the RHYHABSIM (River HYdraulic HABITAT SIMULATION)
model to predict flow conditions and flow variation affect the habitat available
14


to some fish species.
RHYHABSIM uses a combination of hydraulic modeling to predict flow
conditions (depth, velocity) and ecological models to predict the flow
fluctuations of the available habitat to aquatic species
Fish habitat prediction is quantified using the Weighted Usable Area (WUA)

index, where the suitability of the habitat with the assessed organism is
determined. A combination of data on the quantity and relative quality of
available habitats at a given flow is used to calculate the WUA. The WUA
represents an area of suitable habitat for each length or depth of flow (m2 / m).
The study uses the RHYHABSIM model to establish a minimum ecological
flow limit for the Ma River. This process uses the results of the MIKE11
hydrodynamic model to determine the minimum ecological flow required to
help balance the exploitation of water. The process consists of two steps:
- Determine the point at which the habitat of the selected aquatic species
diminishes considerably due to the decrease in flow. That point is called the
inflection point on the curve × environment response flow (WUA);
- Determine the baseline and assess the habitat relative to that flow, which is
usually the lowest annual average flow (MALF).
2.2.3 Surveying, measuring and analyzing methods in laboratory
In the surveyed areas (KS), the study performs such tasks as: collecting aquatic
organisms; collecting water quality samples; accurately measuring some
environmental factors; photograph, observing, and recording natural conditions,
and hydrolizing the survey stations of the Ma River Basin, measurement,
experiment with water samples, aquatic creatures, interviews with local people
and records of all field data recorded on sampling forms including floating
organisms, benthic animals, fish ...

15


Figure 2.27: Map of survey sites, collecting aquatic species downstream of Ma
river
The survey results show that in the area there are 203 fish species belonging to
144 genera, 54 families, 12 families in the downstream area of the Ma river
with the dominant codfish in all taxa. Based on the results of the analysis and

assessment of the ecosystem status on the Ma River, five fish species have been
identified as ecological indicators for assessing aquatic ecosystems on the Ma
River, including: 1) Cyprinus carpio, 2) Cranoglanis henrici, 3) Chelon
subviridis, 4) Eleotris fusca, 5) Glossogobius giuris.
2.3. Hydraulic modeling for the dry season in the Ma river network
2.3.1. River network map
Ma River is a complete river system, so when studying hydrographic and
hydrographic modes downstream, it is necessary to consider the entire river
16


network. The river network includes hydropower calculations covering the
entire main stream and main tributaries of the central and downstream areas of
the Ma River basin, including the Ma River, Buoi River, Chu River, Lung River,
Van Newspaper, Lach Truong River, De Canal.

Figure 2.27: Hydraulic diagram of Ma river network used for calculation
2.3.2. Input data and calculation boundaries
Use of data related to: (i) Riverbed terrain; (ii) Hydrological documents; Water
works along the river.
2.3.3. Simulation, calibration and validation of the model
a. Simulation
To determine hydraulic model parameters and salinity intrusion in the dry
season for downstream Ma River, this study selected the period from 17 ÷
30/03/2010 to calculate the simulation for the hydraulic problem exhaustion –
salinity. This is the time of a tidal in the dry season, with relatively complete
and synchronous observation data. Results of water level, maximum and
minimum saline concentration simulations and actual measurements at some
17

locations on Ma River were also determined.
b. Calculation and validation
To validate the hydraulic model of the dry season for the downstream of Ma
River, in this study, the period from 10 to 22 March 2015 was used to calculate
the model test, which is the time of one tide in the dry season and new data will
be measured in 2015. The results of validation and measurement at some
locations on the Ma River have also been determined.
The simulation results and validation of the hydraulic model of the dry season
in Ma river downstream showed that: (1) The results of the simulation of the
exhausted hydraulic regime at checkpoints with monitoring data for the results
water level, calculated salinity and the actual value of the difference is not
significant; water level process, the salinity in the dry period in 2010 between
the calculation and the relative measure of relative suitability; (2) The results of
the model validation are quite consistent with the survey, so the set of
parameters used in the hydraulic model accurately reflects the hydraulic regime
in the dry season of the Ma river network, with sufficient credibility to carry out
the hydrometric-salinity calculations for other cases in this study.
2.4. Establishment of ecological models downstream of Ma River
2.4.1 Input and calculation boundaries
Input data for the simulation of the model includes two groups of data: field
survey data and a series of multi-year records on river flow. When surveying,
the parameters representing each section of the river sections in hydraulic and
habitat of the indicator species were collected.
- Hydrological data - hydraulic, topography, including survey data in three river
sections on the Ma river mainstream, such as hydrological data, terrain and base.
- Environmental ecological data including 5 species of fish identified as
ecological indicators for assessment of aquatic ecosystems on the Ma River.
2.4.2. Assessment of the suitability of species for environmental conditions
Assessment and analysis of habitat adaptation characteristics of selected species

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under hydraulic conditions, and the substrate characteristics are shown in
Figure 2.36.
A. Cyprinus carpio (Linnaeus, 1758)

B. Cranoglanis henrici (Vaillant, 1893)

C. Chelon subviridis (Valenciennes, 1836)

D. Eleotris fusca (Forster, 1801)

E. Glossogobius giuris (Hamilton, 1822)

Figure 2.36: Adaptability of fish species under different habitat conditions
2.5. Conclusion of Chapter 2
Chapter 2 has identified the factors that influence flow regime in downstream
Ma River, including natural factors and socio-economic activities. In particular,
19


socio-economic activities are the main factors influencing the downstream
flow, especially the change of navigation in recent years, which led to the
lowering of the Ma River. The operation of the waterway works along the river,
causing salinity intrusion into the inland and affecting the habitat of aquatic
species downstream Ma River.
Five species of ecological indicators have been identified to assess aquatic
ecosystems on the Ma River as a basis for the identification of ecological
environment flows.

CHAPTER 3. STUDY RESULTS AND DISCUSSION
3.1. Calculating the minimum flow in downstream of the Ma river
3.1.1. Identify the control points for the minimum flow
Minimum river flow through the control point is "The lowest flow necessary to
maintain the river or river section to ensure the normal development of aquatic
ecosystems and to ensure minimum levels of activity. Exploitation and use of
water resources of water users." Control points for river sections are defined as
follows:
- Section 1 (DKS 1): From Cam Thuy hydrological station to Vinh Khang
intersection, control point at Ly Nhan hydrological station.
- Section 2 (DKS 2): From Vinh Khang junction to Bong junction, checkpoint at
Thet Thon (about 3km far from Vinh Khang intersection).
- Section 3: From Bong junction to Giang intersection, control point at
downstream of Hoang Khanh pump station (2.2 km from Bong crossroad).
3.1.2. Results of hydrographical calculation of dry season in Ma river
By analyzing the results of the case of dry season flow (average dry season,
average dry season, mean monthly dry season and the lowest flow), the years
from 1980 to 2015 show: For 35 years in 1999, the frequency of cases reviewed
at Cam Thuy hydrological station is 99%; the worst stage in the chain since
1989÷1999; The highest flow period in the dry season is from 2000÷2009; In
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the period from 1980÷1988 and 2010÷2015 the flow in the dry season is at
average level.
3.1.3. Identification of the water flow to meet the water demands in river
sections
Based on the water flow of the water source exploitation projects along Ma
River to determine the flow of water needed for the needs of the users of the

river sections downstream Ma river as Table 3.5.
Table 3.5 Flow rate to meet the water demands in river sections
Qmax Qmin
Section
River
(m3/s) (m3/s)
Section 1: Cẩm Thủy ÷ Intersection Vĩnh Khang
Mã 15.55 11.55
Section 2: Intersection Vĩnh Khang ÷ Bông
Mã
4.72
4.72
Section 3: Intersection Bông ÷ Intersection Giàng Mã 14.49
8.89
Section 4: Intersection Giàng ÷ Hoàng Long
Mã
1.25
1.25

Qaver
(m3/s)
14.17
4.72
12.06
1.25

3.1.4. Identification of non-consumed environmental flow
Non-consumed environmental flows include: (1) flow for navigation needs and
(2) flow for ecological environment.
Based on input data, the ecological model RHYHABSIM has constructed

ecological curves that correlate the habitat assessed on the WUA values of fish
species on the Ma River as shown in Figure 3.7, thereby identifying be flow for
ecological environment.
Based on the results of the two above flow components, the study identified the
inevitable environmental flows for the river sections in the lower Ma river
mainstream as follows:
Table 3.15 Non-consumed environmental flow in river sections
Section
Level
Control location Qmtkth (m3/s)
Section 1
No reference
ĐKS 1
51.0
Section 2
IV
ĐKS 2
49.0
Section 3
III
ĐKS 3
61.0

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Section 1

Section 2

Q (m3/s)

Q (m3/s)

Section 3

Q (m3/s)

Figure 3.7: Correlation between habitat assessment on WUA values of fish
species on Ma River
3.1.5. Determination of minimum flow in downstream of Ma river
Based on the results of the calculation of the wastewater flow and the nondrainage environmental flow of the river sections, it is determined. The results
of minimum flow of river sections are as follows:
Table 3.16 Minimum flow of river sections downstream Ma river
Qmtkth
Qmtth
Qtt
River section
Location
River
(m3/s)
(m3/s
(m3/s)
Section 1
ĐKS 1
Mã
51.0
14.17
65.17
Section 2

ĐKS 2
Mã
49.0
4.72
53.72
Section 3
ĐKS 3
Mã
61.0
12.06
73.06
3.2. Analysis of the suitability of the minimum flow
The results of the minimum flow calculation according to the method chosen by
the dessertation are in line with actual flows from 1980÷2015. The method of
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selection of the dessertation has basically considered the full composition of the
minimum flow, more scientifically comprehensive.
3.3. Solutions to maintain the minimum flow in the downstream of the Ma
river
3.3.1. Reservoir operation solution
Operate reservoirs in accordance with Operational Procedure 214/QĐ-TTg;
Operate the reservoirs according to Operation procedure 214/QĐ-TTg, Cua Dat
canal to replace irrigation pumping stations along Ma river with the flow of
15.42 m3/s: in both cases, calculate the lowest flow for the year with the lowest
flow ever occurring on the Ma River (1999, frequency is approximately 99%),
the flow on Ma River can meet the minimum flow requirements set for river
sections downstream of Ma River. When Cua Dat, Hua Na and Trung Son
reservoirs increase the flow in the dry season, the saline concentration can be

reduced so that the pumping stations from Giàng to Ham Dragon bridge can
take advantage of the water supply for agriculture. Thus, when the solution to
maintain the minimum flow on the river downstream of Ma River has been
identified, the requirement for waterway transportation is also guaranteed for
the worst case in 1999.
3.3.2. Proposed management solutions
In order to maintain the minimum flow, the study suggests a number of
management options as follows: (1) Management of discharge to avoid
changing the status of water quality in Ma River; (2) strict management of the
Ma river will ensure that the river bed is not lowered due to economic activities
in the basin; (3) Study of low flow forecast for Ma river basin as the basis for
operating reservoirs in the dry season; (4) Rational crop restructuring for
drought years based on baseline dry run forecast of Ma river basin.
3.4. Conclusion for Chapter 3
Chapter 3 defines the minimum flow for river sections based on two criteria:
ensuring adequate water supply for all sectors (domestic, industrial, agricultural
and navigation) and ensuring the environment ecosystem.
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