MINISTRY OF EDUCATION AND TRAINING
MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT
THUY LOI UNIVERSITY
TRAN KHAC THAC
RESEARCH ON SCIENTIFIC AND PRACTICAL BASES TO PROPOSE APPROPRIATE SITES OF WATER INTAKES TO ENSURE WATER SUPPLY REQUIREMENTS AND CREATE REGULAR FLOW OF DAY RIVER
Specialization : Hydrology
Code
: 9440224
SUMMARY OF ENGINEERING PHD THESIS
HA NOI, 2019
The thesis is completed at: Thuy Loi University
Academic supervisors:
1. Prof. Dr. Pham Thi Huong Lan
2. Prof. Dr. Tan Soon Keat
Reviewer 1:
Reviewer 2:
Reviewer 3:
The thesis will be defended at the Council of thesis assessment at Room 5-K1, Thuyloi University Time: ........... date ......... month ....... year 2019. The thesis can be found from: - Vietnamese National Library - Thuyloi University Library
INTRODUCTION
1. The Essential of the Research
Recently, because of the impacts of climate change and activities of water
exploitation and uses in the Red river basin, the issues of water source decline,
sediments and erosion of conveyance canal bed, especially inlet gate sites have
been normally occurring. Water level of the Red river in dry season is often
getting lower. Particularly in 2010, the water level at Ha Noi area was only at +
0,1m. The weather trend with abnormal and extreme changes has been causing
hundreds of hectares of agricultural land that surfer from lack of water for
irrigation in dry season. The abnormal change of the Red river water level has
been largely affecting water intakes and irrigation pumping stations along the
Red river.
Although there are a number of reports on the issues of sediments at water intake
gates and many solutions have been recommended to reduce the impacts, no
comprehensive studies have been undertaken to such issues to provide scientific
bases for planning and design of water intakes. In the current planning, water
intakes at Day river are with the design flow much greater in compared to those
at the Red river, and the range of the flows between time of taking water in rainy
and dry seasons is also very large. Therefore, the change of conveyance bed at
the gate areas of intakes at Day river is also very complicated in compared to the
existing water intakes at the Red river.
Thus, the study “Research on scientific and practical bases to propose appropriate
sites of water intakes to ensure water supply requirements and create regular flow
for Day river” is essential and urgent to recommend solutions for improving the
efficiency of water taking from the existing water intakes along the Red river.
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2. Objectives and Contents of the Research
- Research to propose indicators for choosing appropriate sites of water intakes
to ensure water taking requirements in dry season and flood discharge in rainy
season;
- Research on appropriate site for water intake of Day river to ensure for socio-
economic development.
3. Objects and Scope of the Research
3.1. Research Objects: Water intakes along the Red river in Ha Noi section and
indicators to determine appropriate site of water intakes.
3.2. Research Scope: The Red river section with the length of 27km from Km30
÷ Km47 +500 (the area of inlet gate of Day river).
4. Approaches and Methods of the Research
4.1. Research Approaches: Systematic approach with solutions from overall to
details and inheriting the results of previous studies.
4.2. Research Methods: Applying the methods of statistical analysis, inheriting
analysis, modeling, and considering expert opinions.
5. Scientific and Practical Implications of the Research
5.1. Scientific Implications: (i) Proposal of indicators for choosing appropriate
sites of water intakes and the method to determine the sites plays an important
role and implies scientific bases since it ensures that water intakes can be
efficiently and safety operated for taking water and draining flood water once
they are built. (ii) Complement the methodology for planning and designing of
water intakes and flood drainage in the river system.
5.2. Practical Implications: Results from successful application of the thesis’s
research to determine appropriate site of water intakes in Day river are considered
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as a good reference source for relevant management agencies in planning,
designing, maintaining and upgrading water intake structures on rivers,
especially using the method of modeling in studying and determining the site of
water intakes because of its outstanding characteristics and the ability of
changing research options in terms of time and modeling results to put into
research.
6. New Contributions of the Research
1) The research has proposed a set of technical indicators and technical
parameters for planning and designing of water intakes along the river.
2) Determination of appropriate site of water intake in Day river to ensure water
supply requirements and create regular flow.
7. Structure of the Thesis: The thesis consists of three chapters as follows:
Chapter 1. Overview of studies on water intakes on the river.
Chapter 2. Research on scientific and practical bases to choose appropriate site
of water intakes to ensure water supply requirements in dry season and draining
flood water in rainy season.
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Chapter 3. Research to choose appropriate site of inlet gate to Day river.
CHAPTER 1. OVERVIEW OF STUDIES ON WATER INTAKES ON THE RIVER
1.1. Studies Undertaken from Different Countries
1.1.1. Studies on classification of water intake structures
According to some studies, the classification of water intake structures consists
of: side water intakes are works with the direction of water flow that forms with
the direction of the main flow of the river with an angle of 90°; front water intakes
are works with the direction of water flow paralleling with the direction of the
main flow of the river; water intakes within a dam; water intakes with regulating
gates; water intakes without regulating gates.
1.1.2. Studies on the change of sediments on the bed of the conveyance river section in the front of inlet gate
By reviewing the studies from the literature, it shows that currently, in order to
assess the change of conveyance bed in general and the change to the front area
of water intakes in particular, four typical methods are often used, such as:
method of measurement, collection and analysis of actual data; method of
experimental formula; physical modeling method; and mathematical modeling
method.
1.1.3. Studies on determining the site of inlet gates
Some studies show that: water intakes should be located at the site of curved river bank, with water taking angle of 600 ÷900, and sluices with water conveyance canals merging with the main canal of about 450 will obtain the highest efficiency;
appropriate water taking angle of sluices on the river bank with straight rivers will be about 300 – 450 to limit the amount of mud and sand to get into the
conveyance canal causing sediments of the front area of the water intakes; the appropriate site in respect to the angle of taking water is about 150-300 in
compared to the main canal and the optimum value for the angle of taking water is about 170-200 to minimize the sediments to get into the canal.
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1.1.4. Studies on solutions to improve the efficiency of water taking
Some solutions have been given such as: solution to control the sediments at
some locations of taking water through measuring, investigating and calculating
the amount of sediments at the site of sluices and pumping stations to improve
the efficiency of taking water of works; solution of pushing the main flow out of
the bank, then to reduce the amount of sediments at the gate of water intakes;
solution of controlling the sediments such as using sediment traps with an appropriate angle of about 300-600; classifying the flow at the gates of water
intakes by using flow dividers.
1.2. Studies in Vietnam
1.2.1. Studies on the change of sediments on the bed of the conveyance river section in the front of inlet gate
Results of investigation show that the issue of sediments at the inlet gate of water
intakes occurs mainly in rainy season. Solutions to the sediment issue of water
intake systems are not very efficient because the substances are mainly alluvium.
However, some options to the issue can be done to reduce the amount of
sediments in the systems by using series of measures with both cases of open
sluices to take alluvium and closed gates without taking water.
1.2.2. Studies on solutions to improve the efficiency of water taking
Several solutions have been proposed such as applying gravity water flow to
supply water to rivers; upgrading discharge deposite tanks of pumping stations
of water intakes,...
1.2.3. Studies relevant to the Red river at the section across Ha Noi
Some relevant studies such as: Research on overall assessment of the changes of
river bed of the Red river at the section of the headwork area of Van Coc – Hat
Mon; Research on modeling to propose scientific bases to renovate and upgrade
the Day flooding drainage system to prevent floods for the Northern Delta;
Research on scientific bases for eliminating flooding areas of the Red, Day and
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Hoang Long rivers; Research on the change of river bed of the Red river and
proposing solutions to stabilize the area of water intakes to Day river; Research
on solutions to stabilize the water intakes and conveyance canal into Day river to
ensure water taking requirements in dry season and flood drainage in rainy
season,...
1.2.4. General remarks on relevant studies in Vietnam with relevance to the content of this thesis
- The consideration of choosing appropriate site of taking water of sluices has
not been paid much attention. Most studies only raise the issue of choosing the
site of setting water intake that should choose at the section of curve river bank.
However, which specific site considered as the best is not clear and this leads to
the issue that the efficiency of water intakes is not high.
- The investigation to propose solutions to reduce sediments at absorption gate
of pumping stations and water intakes has been also paid much attention by
scientist in other countries and in Vietnam. Especially, in the design of water
intakes it takes into account factors that affect water taking, such as:
topographical characteristics in upstream of the works, geological conditions of
the river bank, the rate of water quantity taken into the conveyance canal,
especially in dry season or urgent expansion to avoid the issues of erosion,
sediments of conveyance canal, the width of conveyance canal at the site of
connection with the river, not narrowing down the section of conveyance canals.
However, the determination of appropriate site of water intakes has not been
considered during the design of the works so that many systems are facing the
issue of sediments in the front of water intakes after being built.
- Most previous studies uses models 1D, 2D therefore the assessment of abnormal
gravity flow (divided flow) at the area of water intake gates in order to determine
the requirements for water taking and ensure the quantity and quality. Models to
simulate the changes to the area of water intakes were used with models 1D, 2D
to simulate the conveyance canal, but did not assess the effects of the changes of
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the sediments of water intakes to the issue of water supply in dry season and
drainage of flood discharge in rainy season. The research using 3D model (Pham
Duc Thang 2010) simulated during the rainy season with the condition of closed
gates without taking water, therefore, it could not simulate the hydraulic regime
and sediment movements affecting the site of sluices.
- Most research focusing on assessment of the change of canal bed at the area of
water intake gates, but without focusing on the detail of choosing the location
and site of water intakes to provide bases for improving the efficiency of taking
water of the works.
- There are many studies relating to the Red river, Day river, the area of Day
water intakes, but they mostly focus on research to propose solutions for river
control, stabilization of conveyance bed at the area of Day gates and no ones were
focusing on appropriate sites of sluice gates to ensure water taking requirements
and flood water drainage.
- Existing studies do not take into account the conditions of the flow at the site
of sluice gates to understand how it affects water taking of the sluices. In addition,
the studies do not analyze the relationship between the magnitude of water flow
and the width of conveyance water canal, the length of conveyance canal,
allocation of turbidity by the depth so it causes difficulties in getting water.
- It does not exist of specific indicators to determine the site of sluice gates
because the choice of the site of sluice gate is the first and important task in the
process of designing water intakes.
1.3. Overview of the Research Area
1.3.1. Location of the research area
The research area is located at the section of the Red river focusing on the site of
the sluice gates into Day river from Km30 - Km47+500 of right river bank of the
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Red river with the length of 27km.
1.3.2. Characteristics of topography and geology
The topography is with the slope following the direction from North West –
South East. The upstream area is the sluice inlet gates of Day river at Hat Mon
with the elevation from 3.0 ÷ 10m, and downstream is the outlet gates at Nhu
Tan with the elevation from 0.3 ÷ 5.0m. The bed of the river consists of sediments
with a layer of light yellow sand, a layer of incomplete flora, and a layer of thin
alluvium on top.
1.3.3. Group of the works Cam Dinh – Hiep Thuan
The group of works Cam Dinh – Hiep Thuan consists of: conveyance canal from
the Red river to the upstream of Cam Dinh sluice, Cam Dinh sluice, conveyance
canal Cam Dinh – Hiep Thuan. The mission of the works group includes: (i)
Taking water from the Red river into Day river, in combination with other water
intakes (such as Lien Mac, Tac Giang sluices), generating water flow in dry
season for Day river, providing supplementary water for the downstream to serve
for production activities and domestic uses, improving water environment and
ecosystem, creating flow for water way transport. (ii) Taking charge of flood
diversion from the Red river into Day river.
1.4. Research Directions of the Thesis
- Assessment of the current status, reasons and factors affecting the sediments of water intakes and the ability of taking water of the works across the section of Ha Noi city. - Establishment of a set of technical indicators and parameters for water intakes along the river. - Building a model to simulate the change of conveyance canal at the area of the gates of water intakes, assessing the ability of taking water
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using the set of indicators, then suggesting an appropriate site of water intakes. - Proposing solutions to improve the ability of taking water.
1.5. Conclusions of Chapter 1
Existing studies have not taken into account in depth about how to determine appropriate sites of water intakes, especially applying the theory of divided flow to the area of water intake gates, using the model of gravity hydraulic 3D to calculate and determine appropriate water intakes along the river. Therefore, in order to solve the above limitations, the author will take a research on scientific bases and the change of conveyance canal at the area of water intake gates to recommend appropriate site of Day water taking gates to ensure water supply requirements in dry season and flood drainage to promote socio-economic development.
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Research on scientific and practical bases to propose appropriate site of Day water intake gates to ensure water supply requirements and socio-economic development
Collecting, complementing the existing data, documents regarding the contents of the thesis
Investigating, assessing the current status of water intake works along the Red river, section of Hanoi
Summarizing, analyzing, assessing the data, documents, briefly assessment of the ability of sediments in water intake gates of the works
Assessing the reasons to cause the sediments and the effects on water supply ability for downstream
Building a set of technical indicators (angle of water taking, elevation of conveyance canal bed, the length of conveyance canal,…)
Establishing scenarios to calculate various sites of water intakes with angle of water taking, length of conveyance canal and width of the canal
Models MIKE 11 ST, HD Model MIKE 3FM
Testing the ability of taking water and flush flooding water as required
Determining appropriate site of water intake to ensure water supply requirements and flood drainage
Solutions to increase the ability of taking water
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Figure 1. Diagram of research directions of the thesis
CHAPTER 2. RESEARCH ON SCIENTIFIC AND PRACTICAL BASES TO CHOOSE APPROPRIATE SITE OF WATER INTAKES TO ENSURE WATER SUPPLY REQUIREMENTS IN DRY SEASON AND DRAINING FLOOD WATER IN RAINY SEASON
2.1. Assessment of the Current Status of Some Water Intake Structures along the Red River across Ha Noi
2.1.1. Current status of water intake structures in the area of Ha Noi
The author has conducted an investigation, assessment of some sites of water
intakes along the main flow of the Red river, then proposed a set of indicators to
determine appropriate sites of water intakes such as: Lien Mac sluice: is a main
water intake of Nhue river system located at K53+400 right bank of the Red river;
at the site area of inlet gate of Lien Mac sluice, sediment situation occurs and the
direction of water flow tends to be toward the opposite bank. The angle of taking water is about 120o. If according to the research results of scientists in the world,
the angle of taking water of Lien Mac sluice will be much greater, therefore the
efficiency of taking water is not high; the headwork of Xuan Quan: taking water
from the Red river and being a main works to supply water for Bac Hung Hai
system, sediments occur at the inlet gate of Xuan Quan sluice affecting the water taking. The angle of water taking is about 700, and the mail flow does not direct to the gate of the water intake, affecting the ability of taking water of the sluice,
especially in dry season; Cam Dinh sluice: is a water intake for the canal line of
Cam Dinh – Hiep Thuan belonging to the group of the headwork of Hat Mon –
Day dam, with the actual flow achieving about 27.52% of the designed flow. The
results of investigation show that even in the time of water discharge for winter-
spring season, the water level measured at the upstream of Cam Dinh sluice is
always lower 5.5m, therefore, the ability of taking water of the sluice is very
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low,…
2.1.2. Reasons and factors affecting the ability of taking water of sluices in
recent time in the area of Ha Noi
Most of water intakes have been built for 20 to 30 years, even 40 years for some,
therefore, many works have been deteriorated and do not meet the requirements
of water taking; The section of building works is not secured for the stability as
a result of the effect by the flow causing sediments at the site of inlet gates of the
sluices; Due to the change of lowering down of conveyance canal in recent years,
the water level becomes lower, therefore, many sluices cannot ensure water
taking with designed flow, especially from 2008 up to date; Due to the effect of
regulation regime of the reservoir affecting the ability of supplying water for
water intakes; Due to the ratio of flow diversion in dry season into Duong river
is increasing (some time reaching about 45%) leading to the decrease of the flow
in the Red river; Because of inappropriate design and planning; The increase of
water demand of various economic sectors to meet the requirements for socio-
economic development, therefore, the requirement for water supply is also
increasing and other factors.
2.1.3. Approach of reiteration cycle by regions (III)
Approach of reiteration cycle by each region will combine the level of flooding
for each specific region meaning that the risk can be considered by dividing the
region with potential of flooding into different sub-regions with different levels
of damage and determining the protection level of the sub-regions.
2.2. Theoretical Foundations of Divided Flow/Abnormal Gravity Flow at the Area of Inlet Gates
2.2.1. Basic formula on divided flow/abnormal gravity flow
Taking into account the unstable flow following two dimensions of the divided
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flow at the area of water intake gates as shown in the below figures:
Figure 0. Vertical section of unstable divided flow with two and three dimensions
a. Movement equation:
(2.1)
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b. Continuous equation
c. Flow circulation equation of divided flow
2.2.2. Analysis of choosing a mathematical model to simulate water flow and the change of conveyance canal bed in the area of inlet gates
This thesis uses the hydraulic model one dimension MIKE11 and 3 dimensions
MIKE3FM with modules HD and ST to undertake the study on the change of
conveyance canal and to recommend an appropriate site of water inlet gate to
take water into Day river.
2.3. Proposal of a Set of Indicators to Determine Appropriate Site of Inlet Gates
Appropriate site of water intakes is a place that needs to meet requirements for
socio-economic development and the environment, specifically:
- Technical indicators: to ensure taking water as required (quantity, quality) in
dry season, draining flooding in rainy season, and remaining the stability of the
structures;
- Economic indicators: to ensure the efficiency of the investment, low
investment costs but meeting technical requirements;
- Environmental and social indicators: structures built do not cause negative
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impacts on the environment, society, combined with environmental landscape.
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Table 2.1. Set of indicators for choosing the site of water intake gates
Indicator Specificity
Requirements - The river section with the site of water intake gate should be relatively stable with stable geological conditions and water intake gate without sediments; - The inlet gate of conveyance canal should be chosen at the downstream of the bending peak;
the canal needs Form of the river
on
- The angle generated by the main flow and to ensure downriver flow, and according to the research from scientists and the practice, the angle of taking water α depends topographical the conditions, conveyance canal bed, hydrological and hydraulic regime to determine an appropriate α.
taking into
- Water quantity
the conveyance canal have to ensure the design flow (QP).
Technical indicators (QP,ρ) = f(α, Lcanal, Lbending,Bcanal, J...) Water quantity requirements
- Dimension
- The difference of water level between the starting point and the end point of conveyance canal, and between the main river and the conveyance canal should be minimized. for water section regulation needs to ensure the flow QP - It needs to ensure to take appropriate quantity of alluvium, avoiding taking rough mud and sand into the canal and irrigation area;
Water quality requirements
- The quantity of mud and sand taking into the conveyance canal needs to ratio of ensure an appropriate suspended to provide sediments alluvium for the field, with less mud and sand at the bed of the canal, and water quality is ensured.
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Indicator Specificity
not Works safety requirements
Social – environmental indicators Ensuring landscape, environment and society
Management conditions creates good
Economic indicators
Economics
Requirements It needs to ensure the safety of the structures, causing incidents/damages affecting the safety of the works and residential areas It needs to protect the environment, creating good conditions for tourism development, and integrated use of water sources. Do not cause damage to the environment. Building structures is combined with creating landscape and tourism development. It for management, is convenient applying technical progresses such as electrification and automation, easy for operation, exploitation and uses. It for management of equipment at the gate of water intakes. It needs to have simple and economical structures, easy to operate, repair and maintain. It needs to be convenient for building during the construction period. It needs to easy to undertaking dredging for the first time and annually.
2.4. Conclusions of Chapter 2
The scope of this study focuses on the river section with the inlet gate of Day
river, where there is a sophisticate regime of twisted flow with three dimensions,
the interaction of the flow and conveyance canal bed in the river section with the
sluice causing the flow become complicated, therefore it needs to build a three
dimension model to simulate the hydraulic regime of this area. Using MIKE3
Flow Model FM to calculate and predict the change of hydraulic regime and the
change of the form of the river section of the research area, taking into account
abnormal gravity flow/divided flow to determine an appropriate site of water
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intakes. This is a model that has been studied and applied by many countries,
however, in Vietnam its use is still limited and there are not many studies
applying model MIKE3FM. With the application of three dimension model,
MIKE3 Flow Model FM can simulate in detail research area with three
dimensions, especially at sensitive areas such as the head of the conveyance canal
at Cam Dinh sluice, the affected part of the water intake can be simulated more
in detail and more accurate. This thesis focuses on studying Cam Dinh inlet gate,
then to recommend some solutions to increase the ability of taking water for the
line of the works Cam Dinh – Hiep Thuan to supply water for production in dry
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season and to drain flood water.
CHAPTER 3. RESEARCH TO CHOOSE APPROPRIATE SITE OF INLET GATE TO DAY RIVER
3.1. Model Building and Simulation of Scenarios to Determine Appropriate Site of Water Intake for the Inlet Area of Day River
To study for determining the site of water intake based on the indicators proposed
in Chapter 2, the thesis uses some scenarios for calculation as follows:
Figure 5. Simulated topography of Figure 4. Calculation net of study area study area
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Figure 7. Simulation of the works in Figure 6. Simulated topography of the model study area
Figure 3.1 Scenarios of calculation
Cam Dinh sluice (1) Current site
Cam Dinh sluice (3) Near the site of Hat Mon gate
Cam Dinh sluice (2) Far from current sluice 600m
Length of conveyance canal
Water level of mud and sand
Angle of taking water
Width of conveyance canal
Width of bending river
Calculation with conditions of BDKH and NBD
Calculation to supply water in dry season Qc=100m3/s
Calculation to supply water regular Qtx=450m3/s
Calculation with flooding diversion to Day river 2500m3/s
3.2. Application of Mathematical Model MIKE3FM to Simulate Hydraulic Regime, the Change of Canal Bed of the Inlet Gate of Day River
3.2.1. Determination of the scope and calculation range of the study area
The scope of the research of the model is the Red river section of inlet gate area into Day river running through the boundary of Phuc Tho and Dan Phuong districts of Ha Noi from Km30÷Km43+500 of right bank of the Red river with the topographic data measured in 2007 and complemented measurements in 8/2012. The river section is with the length of 27km, and the right river bank has a water intake works of Cam Dinh to take water into Day river in dry season and Van Coc sluices for flooding diversion to ensure the safety of Ha Noi in case of occurring flooding with the design frequency, and the left river bank is the area of Vinh Phuc province.
3.2.2. Establishment of calculated net system
Based on the scope of calculation for the model, a calculation net system is established. The calculation range of the model is with a dimension of 29991 x
13779 from the set of co-ordinate points with three directions x, y, z. Calculation
net of the model is established with a type of non-structure net (triangle net) and
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solving the problem of finite volume at the center of each net square.
3.2.3. Establishment of calculation topography
The data used for establishing calculation topography consist of: the elevation in
detail of the river bed at the study area: the data measured in 2012 with the scale
of 1:5.000 to calculate and assess the current status of sluices and following
calculation scenarios; the documents of horizontal sections across the length of
the river in the research area; the design documents of Cam Dinh sluice.
3.2.4. Building the model MIKE11 to simulate the flow and sediments to feed
as inputs in the model MIKE3FM
The study and calculation of hydraulic regimes of the Red river and Day river are strictly relevant to the hydraulic regime of all network of the Red river, therefore, the calculation is undertaken for the whole network of the Red and Thai Binh river system.
3.3. Results of calculating the change of canal bed and assessing the ability of taking water at inlet gate area to Day river with various scenarios
3.3.1. Results on assessing the ability of taking water at various sites of water intakes
- After the conveyance canal bed was improved in combined with the new water
intake at Cam Binh, the lowest water level at Ba Tha is 1.61m when the flow taken into Day river is 30m3/s, and is 2.56m when the flow is 100m3/s. At Phu
Ly station, the lowest water level is 0.82m when the flow taken into Day river is 30m3/s, and is 0.84m when the flow is 100m3/s. Thus, the difference of the lowest water levels at Ba Tha when the flows are of 30- 100m3/s is 0.95m, and at Phu
Ly is 0.2m.
- When the conveyance canal bed is improved in combined with new water intake
at Cam Dinh, the ability of taking water at the sites along Day river is with
changes. Water level at sites along the river increases from 0.15-0.1m. This
increase is not significant in compared to the case of improvement of the river
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bed, the efficiency of water intake is not high. Water level at the site before the
river strait of Tan Lang increases sharply, average of from 0.15-0.1m, and the
sites after the strait of Tan Lang to Nhu Tan strait, water level increases slowly,
from 0.05-0.07m.
- The existing water intakes along the river are still in charge of taking water as
designed capacity such as Cam Dinh sluice, however, it needs to consider lower
down the sluice bed.
- After completing the project of water conveyance, improvement of Tich river via the canal San-Thuy Duc (20m3/s) and Xuan Phu pumping station (5m3/s), the
lowest water level at Day river will remain stable at Ba Tha from 1.57-1.60m (when the sluice of Cam Dinh conveys water with the flow Q = 30m3/s), Mai Linh from 3.33-3.94m (when QCamDinh = 70m3/s), Phu Ly from 0.33-0.84m (when QCamDinh = 100m3/s). The water level at sites along the river is approximate with the level when there is a new water intake at Cam Dinh. In order to increase the
water level at sites along the river, it should implement some measures of non-
structure such as: improving the management, exploitation of water source along
the river, limiting the exploitation of sand to maintain the form of the river bed
as the stable form after the conveyance bed is improved. It also needs to consider
the issue of decreasing water source to supply for agricultural production. Thus:
If more water is supplemented from Tich river to Day river, the difference of the
water level at sites along the river is low in compared to that in case of improving
the conveyance bed of Day river and building more water intakes, with the
difference of from 10-15cm, and with this difference of the water level, an
investment to build more new water intakes is not feasible since the costs would
be high, the structures are built on weak geology foundation therefore the
efficiency is not high.
3.3.2. Assessment of the change of conveyance canal bed with scenarios of various sites of water intakes
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Simulation of the change of conveyance bed with the option of water conveyance via Cam Dinh sluice into Day river with the flow Q=450m3/s. Water intake is set
at Cam Dinh (beside the current Cam Dinh sluice). Implementing the simulation
to assess hydraulic regime of mud and sand at the site of the headwork sluice.
The velocity of the flow in canal Cam Dinh is mainly at the value of 0.7m/s -
0.8m/s, at the area of the sluice of Cam Dinh to take water in dry season and the
new headwork sluice is with the velocity of from 1.1m/s – 1.2m/s. The central
flow has a trend of deviating to the right river bank close to the area of inlet gate
to Day river.
When flood water is diverted into Day river with the flow Q=2,500m3/s the main
flow becomes more close to the right river bank, especially at the area of close to
Cam Dinh sluice and the new flood diversion works of Van Coc. The flow at the
area close to the water intake reaches about 1.6m/s, the flow running over the
alluvial ground with a high velocity into Van Coc flood diversion sluice,
therefore, it forms a field of driving force toward the new flood diversion works
of Van Coc, and the highest velocity in the area reaches 1.7m/s. The velocity of
the flow running over the section of Cam Dinh sluice is very high, from 1.9-
2.0m/s and gradually decreasing when running toward downstream of the sluice
with the main flow of flood discharge line focusing on Cam Dinh canal then
running through Cam Dinh canal to the downstream.
3.4. Proposal of appropriate site of water intake to ensure water supply
requirements and flood discharge into Day river
3.4.1. Determining the site of water intake to remain water supply as required
Based on the calculation results from various scenarios and the set of indicators
given in Table 2.2, exporting the calculation results from model MIKE3FM to
establish the relationships between required water flow, water level at the site of
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water inlet gate of conveyance canal of Cam Dinh sluice on the Red river and the
angle of taking water, the length of bending section, length of the conveyance canal, the results are given below:
Figure 8: Calculation results of correlations for Cam Dinh sluice
Water intakes should be set at stable river section with the shape of bending at
sunken bank toward downstream in compared to the peak of bending section with
the deepest site; Water intakes should not contribute to the change of river bed
and should ensure the task of water taking with the lowest amount of mud and
sand; Do not set water intakes at the river section in the downstream with the
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intersection of water flows of river branches with much mud and sand. The length
of bending section at different sites of water intakes in the Red river section at
the area of inlet gates into Day river as below:
At the site of Cam Dinh water intake, the length of bending section is about
5,070m.
At the site of Van Coc sluice, the length of bending section is about 5,460m, and
in this river section, the flow tends to be stable, and a water intake is proposed to
build at this site to take advantages of the flow of the Red river at the area of inlet
gate of Day river.
At the site of Hat Mon, the length of bending section is about 3,300m, with the
aim to recover the flow as used to be of Day river.
An appropriate angle of taking water is from 720÷780, then the flow in the conveyance canal is about 36,24÷160 m3/s, the length of bending river section that is appropriate to ensure taking water with the design flow of 36.24m3/s is
from 4,500÷5,900m. An appropriate length of the conveyance canal is from
30÷60m. When the flow in the Red river at the location of Cam Dinh is about
6500m3/s, the amount of mud and sand getting into the sluice gate is about
0.4kg/s. Therefore, the issue of sediments will not occur in the conveyance canal.
3.4.2. Recommendation to propose appropriate site for Day water intake to
ensure water supply requirements and flood water drainage
With the results of hydraulic calculation, the investigation results and analysis of
the relationships between the flow – water level – angle of taking water – length
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of the bending river section – requirements of water quality (alluvium quantity
for irrigation), the sites of water intakes are proposed at Cam Dinh, Van Coc and
Hat Mon with strengths and weaknesses as given in Table 3.1.
- Choosing the site of water intake at Cam Dinh needs to implement several
solutions as below:
+ Change the angle of taking water from the Red river to Cam Dinh sluice;
+ Improve the conveyance canal from the Red river to Cam Dinh sluice;
+ Improve Cam Dinh sluice to ensure the design flow for water taking when the
water level of the Red river reduces;
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+ Improve the canal Cam Dinh – Hiep Thuan.
Table 3.1. Assessment of indicators to choose the site of water intakes
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Indicator Cam Dinh Van Coc
Be able to achieve the flow as designed
The angle of taking water is not appropriate and the problem of sediments occurs at the area of water intake gate The angle of taking water is appropriate and the area in the front of sluice gate, river bed is with the trend of approaching close to the right river bank
Set the site of the works at stable section of the river At the sunken bank of the bending river section with Lbending=5,070m The length of the conveyance canal Lcanal = 580m
Ensure water quality
Water quality taken into the canal ensures an appropriate amount of suspended mud and sand to improve the quality of field, the quality of water taken is ensured
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Social - environment al issues At the sunken bank of the bending river section with Lbending= 5,460m The length of the conveyance canal Lcanal = 540m Water quality taken into the canal ensures an appropriate amount of suspended mud and sand to improve the quality of field, less of deposit substances, the quality of water taken is ensured Ensure the landscape, environmental and social aspects, and structure safety Hat Mon The angle of taking water is not appropriate and the problem of sediments occurs at the area of water intake gate, and the formation of alluvial ground near intake gate At the sunken bank of the bending river section with Lbending= 3,300m The length of the conveyance canal Lcanal = 2,370m Water quality taken into the canal ensures an appropriate amount of suspended mud and sand to improve the quality of field, less of deposit substances, the quality of water taken is ensured Ensure the landscape, environmental and social aspects, and structure safety Ensure the landscape, environmental and social aspects, and structure safety
Indicator Van Coc Hat Mon
Economics
Total cost is high because it needs to build new canal system, sluices, conveyance canal.
Total cost is high because it needs to build new sluice system and conveyance canal, dredging the bed of the current conveyance river of Day river. Cam Dinh Total cost is low since it can use the existing canal system, construct new conveyance canal, improve the elevation of Cam Dinh sluice bed to ensure water taking with the design flow
- Choosing the site of Cam Dinh 2 water intake needs to implement some
solutions as follows:
+ Build a new conveyance canal from the Red river to Van Coc sluice;
+ Improve and upgrade Van Coc sluice to ensure water supply requirements as
designed when the water level of the Red river reduces;
+ Build a new conveyance canal Van Coc – Hiep Thuan.
- Choosing the site of Cam Dinh 3 water intake needs to implement several
solutions as below:
+ Build a new conveyance canal from the Red river to Hat Mon sluice;
+Build Cam Dinh 3 sluice to ensure water supply requirements as designed when
water level of the Red river reduces;
+ Dredge the bed of the current Day river to ensure water supply requirements as
designed.
Based on the analysis of conditions regarding economic, technical,
environmental – social aspects, it shows that if a new sluice of Cam Dinh 2 is
built close to Van Coc sluice to ensure both water supply and flood drainage.
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Cam Dinh 1 is remained, combined with taking water with Cam Dinh 2 sluice.
The calculation for checking shows that the results of water taking at Cam Dinh
2 sluice in dry season as follows:
Figure 9. Relationship between the flow and water level at Cam Dinh sluice in
dry season
3.5. Recommendations of some solutions to increase the ability of water
supply in dry season and flood drainage of Cam Dinh sluice
3.5.1. Non-structure solutions
a. Dredging of conveyance canal at upstream of Cam Dinh sluice
Dredging the conveyance canal at upstream of Cam Dinh sluice to improve the
capacity of the sluice. The system of Cam Dinh sluice has been much deposited,
especially at the head of the conveyance canal connecting to the Red river,
therefore it needs to dredge annually to ensure the requirements for water supply.
b. Protection of water source
Protecting water source by appropriate policies is the solution to justify the
allocation of water following the way that reduces the flow in rainy season and
increases the flow in dry season by using some solutions: Protecting and planting
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forest; Applying measures for sustainable water resource development planning
and management; Increasing the use of return water; Appropriate water source
allocation; Appropriate use, water saving and efficient use.
c. Appropriate exploitation and uses
It needs to study and implement solutions to change the form of water
management from traditional management measures “meeting the demand,
provide to all needs„ to water demand management; implementing the
management of hydro-power-irrigation reservoirs using new measures to
increase the efficiency of integrated water resource exploitation, firstly to
establish a coordination mechanism among ministries, sectors and provinces to
make changes in the management and operation of reservoirs to supply water for
downstream areas.
d. Establishment of appropriate sluices management and operation processes
In rainy season, when operating the sluice, it should open the gate high to increase
the flow to avoid the deposits inside the sluice.
Taking the advantage of the large difference between the upstream and
downstream water levels, open the gate high to flush deposits in the area of sluice
gate.
In rainy season, it should consider the issues of preventing floods in the basin to
operate the sluice gate to flush deposits to the river.
In addition, the project of supplementing water from Tich river to Day river also
contributes to supply enough water in dry season and regular flow to recover the
flow of Day river.
3.5.2. Structure solutions
a. Structure solutions aim to maintain the stability of the bank, increase the ability
of taking water
b. Solution of changing the angle of taking water into the conveyance canal of
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Cam Dinh sluice
c. Solution of upgrading the structure of Cam Dinh sluice
d. Solution of remaining the current Cam Dinh sluice and building a new Cam
Dinh 2 sluice at the site close to Van Coc sluice that is 600m far from the current
Cam Dinh sluice toward downstream.
3.6. Conclusion of Chapter 3
The thesis has proposed appropriate sites of water intakes for the area of Day
inlet using the set of given indicators and recommended some structure and non-
structure solutions to increase the ability of water taking at the locations of
proposed works. The results show that in order to increase the efficiency of water
taking from the Red river into Day river, an optimum solution is to remain the
current Cam Dinh sluice and build a new sluice far away of 600m from the existing sluice, with an appropriate angle of water taking of from 720÷780, the length of the bending river section to ensure taking water with a design flow of 36.24m3/s is from 4,500÷5,900m, and the length of conveyance canal is from
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30÷60m.
CONCLUSIONS AND RECOMMANDATIONS
Conclusions: The thesis uses the tool of mathematical model three dimensions
(3D) to simulate group of structures controlling the Red river at the area of water
intake of Day river, simulating the interactive effects between structures within
the overall of the Red river system. This is an approach that can assess the effects
more accurate to propose specific structure solutions for the Red river section in
the area of Day water intake.
New contributions of the thesis:
- The thesis has proposed a set of technical indicators and technical parameters
for planning and design of water intakes along the river.
- The thesis determined the appropriate site of water intake into Day river to
ensure water supply requirements and create regular flow.
Recommendations: Due to the limited time, this research was only to determine
the site of water intakes for three sites of the inlet area of Day river with 48
calculated scenarios, it needs to put more efforts to complete the model,
experimental studies for other river sections with the area belonging to the inlet
areas such as at Xuan Quan, Phu Sa,... with many different sites of water intakes.
In studies to choose and build water gates, some solutions can be applied to
increase QP and stabilize the conveyance canals of the intakes as follows: (i)
Build dam to diverse the flow toward the water inlet; (ii) At water inlets with
regulation gates, in order to reduce the ability of sediments of conveyance canals,
it should to build a wall system between the inlet gate and the main flow to
prevent mud and sand, garages to get in the canal causing deposits and sediments
of conveyance canals.
It needs to calculate to test structure solutions to protect the bank based on
simulating topography in detail of the basin, therefore, the feasibility of the
choice of the water intake to ensure water supply requirements in dry season will
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increase.
In the future, if possible, a physical model should be built to simulate the change
of river bed and determine appropriate sites for water intakes to recheck the
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feasibility of solutions proposed from this thesis.
LIST OF PUBLICATIONS RELATING TO THE THESIS
1. Tran Khac Thac “Research on scientific and practical bases to determine appropriate site of water intake into Day river ” Journal of Water Resources and Environmental Engineering - Issue 59 (12/2017).
2. Tran Khac Thac, Pham Thi Huong Lan “Research to propose indicators to determine water intake along the river – applying for water intake into Day river ” Proceedings of the Annual Conference of Thuyloi University, Thuyloi University, 2017.
3. Tran Khac Thac, Pham Thi Huong Lan “Application of hydraulic model to assess the change of conveyance canal bed in the area of inlet gate into Day river” Proceedings of the Annual Conference of Thuyloi University, Thuyloi University, 2017.
4. Pham Thi Huong Lan, Tran Khac Thac “Research on the change of conveyance canal bed for the section of Day river inlet gate following regular supply scenario and proposing control solutions” Proceedings of the Annual Conference of Thuyloi University, Thuyloi University, 2013.
5. Tran Khac Thac, Pham Thi Huong Lan, Ha Van Khoi “Research to apply model MIKE11 in assessing the ability of conveyance water to Day river to increase the capacity for flood discharge, and improve the environment” Journal of Water Resources and Environmental Engineering, Issue 40 (3/2013).
6. Tran Khac Thac, An Tuan Anh “Assessing the possibility to apply Mike 21FM in studying the changes of Day inlet gate” Journal of Water Resources and Environmental Engineering, Issue 29 (6/2010).
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7. Pham Thi Huong Lan, Tran Khac Thac, An Tuan Anh “Some issues in analyzing and choosing calculated model in assessing the changes of conveyance canal of Dong Nai – Sai Gon river in the area of Ho Chi Minh city under the impacts of anti-flooding works”, Journal of Water Resources and Environmental Engineering, Issue 29 (6/2010).
