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<small>XMINSTRYOEEDLCXHONANDTRAINING MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT</small>
Nguyen Vinh Nguyen
‘THESIS OF MASTER DEGREE
1. Assoc. Prof. Dr. Nguyen Mai Dang
‘This research is done for the partial fulfilment of requirement for Master of Science Degree at Thuyloi University
(This Master Programme is supported by NICHE ~ VNM 106 Project)
‘November, 2017
</div><span class="text_page_counter">Trang 3</span><div class="page_container" data-page="3">Thereby certify that the work which is being presented in this thesis entitled, “Impact assessment of Regulation works in the Thai Bình river downstream” in partial
under super
Van Quan.
ision(s) of Assoc. Prof. Dr. Nguyen Mai Dang and Assoc. Prof. Dr. Ngo
‘The matter embodied in this thesis has not been submitted by me for the award of any other degree or diploma
Date: 19/11/2017 Signature
Nguyen Vinh Nguyen
</div><span class="text_page_counter">Trang 4</span><div class="page_container" data-page="4">‘The Thai Binh River System's downstream is a major economic region whieh is located in the Red River Delta including Hai Phong city and Thai Binh province.
‘Therefore, a research regarding current water allocation assessment need and hhas (© be conducted in order to find out appropriate solutions for solving and surmounting the issues. In this study, the MIKE 11 model was used to simulate the recent status of the system and prediet the water distribution according to some proposed scenarios based on the system operation in the future
‘The study determined the existing problems and troubles in water distribution and water use in the Thai Binh River downstream, Accordingly. the impact of structural measures proposed in this study on flow changing also was analyzed in details, In addition, the study ilustrated thatthe flow discharge of rivers in the system will be changed significantly after building the regulated structure works. In addition,
the study proposed some alternatives aiming to strengthen the management of sy
operation as well as water use in the downstream of Thai Binh River.
Key words: Red River Basin, Thai Binh River, MIKE 11 model, flow regime
</div><span class="text_page_counter">Trang 5</span><div class="page_container" data-page="5">I would like to give a big thank to all people who have supported and assisted me during my master th research. Thanks for their support, encouragement and
Especially, I would like to express my appreciation to Assoc. Dr. Nguyen Mai Dang and Assoc. Dr. Ngo Van Quan for their unlimited encouragement, guidance, comments and technical supports as well as the thesis writing process from the beginning of this thesis research,
1 wish to thank Dr, Ilyas Masih, Assoc. Dr, Nguyen Thu Hien and Assoe. Dr. [Ngo Le An for their feedbacks, references and support on the proposal process.
also want to thank to all instructors and staff of Thuy Loi University who have helped me a lot during the master course.
1 would like to give my appreciation to Dr. Ho Viet Cuong, Mse. Nguyen Thi Ngoc Nhan, Msc, Nguyen Van Bach and Mr. Phan Van Thanh who was willing to help me with modelling application in the thesis.
1 also would like to thank the National Key Laboratory of River and Coastal Engineering and Institute of Vietnam Academy for Water Resources for their information and useful data input.
Last but not . Lwant to take this opportunity to show my appreciation to my family, friends for their inspiration and support throughout my life; this research is simply impossible without you,
</div><span class="text_page_counter">Trang 6</span><div class="page_container" data-page="6">3.1. Description of the study area.
3.1.1 Geography and River Network. 18 3.1.2 Climatic characteristics 20 3.1.3 Hydrological characteristics 23 3.1.4 Tide and tidal effects in the river mouth 26 3.2. Water deman
3.2.1 Water demand for agriculture. 2 3.2.2 Water demand for aquaculture 28 3.2.3 Water demand for industry 29 3.2.4 Water demand for domestic. 29
4. METHODOLOGY,
4.1.1 Governing Equations. 33 4.1.2 Methods used in the performance evaluation. 34
4.2.1, Input data 35 4.2.1.2 Boundary conditions. 37 4.2.1.3 Cross-sections. 38
</div><span class="text_page_counter">Trang 7</span><div class="page_container" data-page="7">4.2.1.4 Meteorological and hydrological data 39 4.3, Modeling calibration ..
43.1, Step by step.
4.3.2 Initial conditions setup 40 4.3.3 Calibrating the hydraulic parameters 40 4.3.4, Modeling calibration in flood season ái
4.4.1 Modeling validation in flood season 48 4.4.2 Modeling validation in dry season
4.5. Proposed regulation works and scenarios.. 4.5.1, Proposed regulation works
4.5.2, Simulated Scenarios 5ã 5. RESULTS AND DISCUSSIONS.
$1. Scenario results simulated in August 1996. 5.2. Scenario results simulated in January 200%
List of figure
Figure 1.1 Thai Binh River downstream area 8 Figure 2.1 Simulation interface file of Mike 11 (HD Module) 15 Figure 3.1: Map of the study area focus on two districts: Vinh Bao and Tien Lang....18 Figure 4.1: The research flowchart. 32 Figure 4.2: Schematic of network and reservoirs considered in the Red River basin...36 Figure 4.3: River network for simulation by Mike 11 model 37 Figure 4.4. Model calibration process 39 Figure 4.5: Hydraulic parameters interface 4 Figure 4.6: The observed and simulated water levels for the 1996 flood event at Ha Noi station in the case of calibration 4 igure 47: The observed and simulated water level in Van Uc River in 1/2006 — ‘Trung Trang Station 45 igure 4.8: The observed and simulated water level in Duong River in January 2006 —
Figure 5.14: Simulated water level of PA 1+2+3. Figure 5.15: Simulated discharge of PA 1+2+3. Figure 5.16: Actual water level at the selected points Figure 5.17: Actual discharge at the selected points
Figure 5.25: Simulated discharge of PAL+2 Figure 5.26: Simulated water level of PA 1+3 Figure 5.27: Simulated discharge of PA1+3 Figure 5.28: Simulated water level of PA1+2+3 Figure 5.29: Simulated discharge of PAL+2+3.
</div><span class="text_page_counter">Trang 10</span><div class="page_container" data-page="10">List of table
Table 2.1 Comparison of different One-Dimensional (1D) models. 12 Table 3.1, Monthly average temperature of the year at stations 21 Table 3.2 Typical average monthly rainfall at stations 2
Table 5.1 Comparison between actual and simulated flows of PAI 56
Water is a useful natural resource and plays an important role in human being ‘The water users in a river basing include some stakeholders such as agriculture, industry, households, recreation and environment. Obviously all human activities demand and need fresh water. Fresh water is extremely essential for lives; no other
Nowadays, people have been using water resources <small>in negative way.</small>
Accordingly, water quality and quantity are both declining significantly. There are some reasons for this statement including the effects of natural conditions, climate change, economic and social development, over exploitation of natural resources as ‘well as the poor management oflocal authorities,
Water crisis has been increasing and affecting widely all over the world. It is about L2 billion people; similar to 1/5 global population, living in water shortage ‘areas and other 500 million people are being exposed by this trouble. Water shortage is caused by natural phenomena and human activities. Fresh water is available everywhere in our planet and much enough for human. However, fresh water is
Based on the report of Ministry of Natural Resources and Environment (2009). Vietnam has about 3450 rivers with above 10 kilometers length. There are 206 water sources which are considered as external water resources, Accordingly, total annual
‘water volume is about 830 bil m the biggest fet systems. Total potential
and mountainous regions (Le Mai, 2013). It can be seen that Vietnam has a lot of,
</div><span class="text_page_counter">Trang 12</span><div class="page_container" data-page="12">water due to the heavy rainy season and dense river intensity. However, droughts and large scale water shortage occurred regularly in many provinces. Vietnam currently has many challenges regarding water resources management, In addition, Vietnam is ranked as one of the most affected countries by climate change and sea level rise.
Hydrological models have been used frequently in water resources planning and management such as hydrological forecasting, reservoir operation, water qualit research on flood, inundation and drought, designing irrigation system and supporting for the integrated water resources management. An appropriate model selection is ntial for each research project. These selections thereby have to be based on study objectives, considering input data and output data, expected results and solutions.
There are many studies on the water field that use models as effective tools to solve problems. The MIKE 11 model has been developed by DHI Water and Environment (Danish hydraulic institute) and is used popularly in Vietnam, This model is a
sediment transport in estuaries, rivers, irigation system, channels and others bodies
proposed management
</div><span class="text_page_counter">Trang 13</span><div class="page_container" data-page="13">1.2. Problem statement
<small>“THAI mint</small>
Figure 1.1 Thai Binh River downstream area,
‘According to the report of Hai Phong Department of Agriculture and Rural Development, In the Thai Binh River's downstream, salt intrusion at river mouths is increasingly happening because of the natural water distribution and sediment (Luoe river moving and developing on the left side of Van Ue River - Figure 1.1), Thai Binh
will influence strongly on the socio-economic development of Tien Lang and Vinh. Bao districts. Because, these two areas play a role as key development of agricultural areas as well as water demand would be increased significantly,
at Do Son Beach due to the In addition, sediment transport is currently increasi
water diversion to Van Uc River leading to amount of sediment flowing to the sea This will affect tourism and economic development of Hai Phong City.
Overall objective is to assess the impact of water regulation works in the downstream of Thai Binh River by using hydrodynamic model. To achieve the main objectives, the thesis consists of some detailed goals as follows:
+ Using the MIKE 11 to simulate the flow regimes according t0 proposed solutions and scenarios in order to suggest the water allocation
+ Determining the water diversion between Red River and Thai Binh River in
Bình river's downstream located in Hai Phong province. Main purpose of the Constructions is to increase the flow in Thai Binh river and to decrease the flow in Van Uc river, Also, other purpose is to prevent saltwater intrusion in Thai Bình river as well
+ Proposing solutions for water allocation, water usage<small>e, water management in</small>
‘order o enhance the quality of water use in the study area,
1.2.2, Research questions
‘What is the current status of water use in the Thai Binh River passing Hai Phong city?
How does the flow regime in Thai Binh river's downstream area change if regulation works added?
‘What is the effective solution of water management?
</div><span class="text_page_counter">Trang 15</span><div class="page_container" data-page="15">1.2.8. Thesis overview
‘Structure of the thesis includes those parts:
Chapter 1: Introduction, presents problem statement, needs of study, research objectives, and overview of the study area
Chapter 2: Literature review, reviews the previous studies related to the content and cope of this research. An overview of hydrodynamic models also analyzed here. MIKE 11 model will be presented in this chapter as well,
Chapter 3: Study area and data collection, presents the natural conditions, climatic characteristies of the study area as well as the population character economics and society. The water demand and management are also discussed in this study.
Chapter 4: Metholodology, shows the methodology and steps to achieve the ‘objectives of the thesis. The chapter discusses the data input as well. Modeling calibration and validation are also presented here.
Chapter 5: Results and discussions, analyses the model performances (MIKE 11) in order to obtain the research objectives.
Chapter 6: Cconclussions and recommendations, focuses on findings and recommendations, and future research.
In this chapter, existed issues, needs of study, research objectives were be showed, Because of the uneven river flow distribution between the Van Uc river and ‘Thai Binh river in the study area, Thai Binh river has high sedimentvolume and salt intrusion and Van Uc river has the erosion.
</div><span class="text_page_counter">Trang 16</span><div class="page_container" data-page="16">2.1. Over -w of Hydrodynamic Model
Any scientific field always needs to develop some processes such as monitoring data, recording and measuring data, simulation and explanation of natural phenomena, To have a better understanding of the processes of hydrology, they can be deseribed in laboratories by physical models. Besides that numerical models have been developed
Estuaries can be seen as potential and valuable natural resources of environment, society and economics (Nordstrom, 1992), The research on sediment transportation in estuaries is normally difficult due to the fluctuation of sediment and impacts of other natural factors. The s sdiment transportation process on rivers is relatively complicated including erosion process, sediment transport and deposition. Those processes relate t0 flow regimes, particles characte ies, size and shape, and intensity and elements of the particles. The morphological changes are the results of the nonlinear interaction between water and sediment and river bed (Hibma et al, 2004), However, numerical models are used as valuable tools for simulation of natural phenomena due to the
013). physical processes and numerical technique (Jiang, Ranasinghe & Cowell
in
</div><span class="text_page_counter">Trang 17</span><div class="page_container" data-page="17">There are many numerical models from open sources, for example Delft3D. developed by Deltares to commercial models MIKE models developed by DHI. A lot Of hydraulic models that simulate the hydrologic regimes and sediment transport have been considered aiming to obtain an appropriate model. The selected model need to be considered with many factors such as management, variables and main process, data available, and input and proposed solutions (Boorman et al., 2007). Hence, the input data of various models have to be collected aiming to get best understanding of advantages and disadvantages of them before the model application, Table 2,1 shows the comparison of different hydrodynamic models,
Eventually, according to the author's knowledge, natural conditions of the study area and available input, MIKE I1 model was selected as an effective tool for achieving the research study
Table 2.1 Comparison of different One-Dimensional (1D) models
Model [SWAT (Amoldet | MIKE TL HEC-RAS TRE
al,, 1995; Ndomba | (Doulgeris et al, | (Pappenberger et | (Vanet al.,
Manag |SWAT model was | The Mike 11 model | HEC-RAS model is | ISIS is a full cement | developed predict | isa software used forvariety | hydrodynamic issue | the impact of land | package for the | types of projects | simulator for
sediment, and | sediment transport in | flow regimes. The | levels in open
chemical yields in | channels and other | multiple purposes. | estuaries. large and complex | water bodies,
Taput | -DEM “Hydrological “Reach neiwork | “Hydrological
<small>“Climate data “Meteorological | -Unsteady low | Geometry“Hydrological data. | Sediment “Sediment Sediment</small>
sdiment load concentration Key | The model is based | The model based | HEC-RAS modslis | The model is Variable | on the water fon Saint Venant’s | based onthe | based on one
And | balance equation | equation for continuity equation | dimensional process | for the soil water | continuity and and momentum | Saint Venant’s
<small>content ‘momentum equation. | equation equations.</small>
</div><span class="text_page_counter">Trang 18</span><div class="page_container" data-page="18">al., 1995; Ndomba | (Doulgeris et al, | (Pappenberger et | (Van et al.,
Key |= Waierquality | Discharge -Sưeam Flow “Runoif
output | -Stream flow Water level Water level Water quality Surface runoff | -Water quality Sediment scour | -Sediment Sediment yield | -Sediment transport_| and deposition
Time | Dailytime step | Sec, Minute, Hourly | Minute, Hourly, | Minute Step and daily time step. | Dail Hourly: Daily
‘Access [The user can | The user has lo pay | The user can access | The users can
bility to | access to modify | to use the model and | to modify the code | access freely
coding | model
Software |The SWAT model | This isnot open [IL is a_ public | ID component
cost | is free and a public | source software. | domain and free of | as well asthe domain software, | The model is very | charge from HEC’s | whole ISIS
Free for users,
(Source: Tania Hassan, 2016)
2.2, Briefs of Mike 11 Model
Modelling of rivers and channels, MIKE 11 is a versatile ID modelling package covering more application areas than any other river modelling package available. MIKE. 11 is a fully dynamic, one-dimensional modelling package. It includes comprehensive facilites for modelling complex river channel networks, lakes and
<small>structures</small> lowing users to define complex control strategies as well as dam break structures. Additional application areas include, rainfall-runoff, flood modelling, ecology and water quality, real time forecasting and sediment transport and river morphology assessments (DHI, 2007), MIKE 11 has been used widely all over the ‘world. The model includes some modules as follows:
‘© AD Advection-Dispersion,
B
</div><span class="text_page_counter">Trang 19</span><div class="page_container" data-page="19">‘This study estimates the proportion of sediment transportation before and after building reservoir systems on the Red River. Un-coherence sediment transportation
+ Flood analysis and flood alleviation design studies
<small>+ Realtime flood or drought forecasting</small>
+ Dam break analysis
<small>+ Optimization of reservoir and canal gate and structure operations</small>
<small>+ Ecological and water quality assessments in rivers and wetlands</small>
© Water quality forecasting
+ Sediment transport and long ferm asse fer morphology changes
Salinity intrusion in rivers and estuaries
</div><span class="text_page_counter">Trang 20</span><div class="page_container" data-page="20"><small>+ Wetland restoration studies</small>
<small>«Integrated modelling of river and groundwater interaction</small>
+ Time series files *. DESO
+ HD parameter file HDI
<small>+ Simulation editor *.SIML1</small>
Figure 2.1 Simulation interface file of Mike II (HD Module) 2.3, Applications of Hydro-dynamic Model
All over the world, many researchers have experimented in order to estimate the flow changing (Yan et al, 2010, Lajoie et al, 2007, Matteau et al, 2009; Magilligan
15
</div><span class="text_page_counter">Trang 21</span><div class="page_container" data-page="21">and Nislow, 2005). Using the MIKE 11 model has become popular nowadays because of the effective simulation of model
‘Many kinds of hydraulic models have been applied widely in solving water resources issues such as ID models (MIKE 11, HEC- RAS, etc...) and 2D models
(MIKE 21, TUFLOW, F 3D...). In Vietnam, especially the MIKE models have ‘gained popularity lately. These packages have been developed by the DHI water and environment (Danish Hydraulic Institute), which is a global organization dedicated to solving challenges in water environments worldwide. There is the question is how much is modelling needed? Robyn Johnston and Vladimir Smakhtin illustrated that
update Jiang etal, 2013),
s, wave, sediment transportation and depth,
‘To simulate the flows, except MIKE 11, number of models have been considered such as Q_SDM_BASIN_2014 (Dao Tan Quy, 2013), using 1-2D model to assess the effects of constructions on rivers on flow regime and salinity intrusion at
applied in many projects (Nguyen Thanh Hung et al, 2015, Nguyen Van Tuan et al, 2014). However, the studies concentrated on surrounding areas and large scale as well as lack of information from the study area, Studying on the downstream area of Thai Binh river need to have available data and detailed conditions of study area. In year 2016,1 tia Hasan and others studied for Hai Phong area. However, this study was: only concentrated on sediment transportation due to the interaction of upstream
<small>reservoir systems.</small>
In order to solve completely the existing issues on the study area, this study will focus on gathering input data including natural conditions, society, water demands,
water management in Thai Binh River, Hai Phong city. Besides, to strengthen the
effectiveness and accuracy of MIKE 11, this study will simulate the flood flow and dry flow by implementing the model calibration and validation processes.
‘The chapter presented overview of hydrodynamic model and focus on the MIKE 11 model. Some reviews the previous studies related to the content and cope of this research were be presented as well. Unlike previous studies, the study used two sets of parameters for the Mike model in the dry season and flood season. The specificconditions of study area were be showed
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</div><span class="text_page_counter">Trang 23</span><div class="page_container" data-page="23">3.1, Description of Study Area
‘The Thai Binh River is included over 275 km length and 11 branches and estuaries in downstream. These branches transfer the entire flows from Thai Binh River to four
‘The geographic location of the study area shown as follows:
+ Bound by the East sea in the East direction, bordered with Van Uc river in the
+ Bordered with Hai Duong province in the North-West direction, bound by ‘Moi and Luoe rivers defined from the conjunction of Hoa and Luoe rivers to the conjunction of Moi and Van Ue Rivers,
‘Topography and geomorphology of Thai Binh River downstream are the results of geologic movement in million years in relation with sediment deposition of the Red and ‘Thai Binh River basins. It can divide the geography into two main regions: the northern partis lowland terrace with hilly regions, the southem part is remained delta area,
The delta area has elevation fluctuating from 2.50 m up to 3.50 m and the clevation declining from the West to the East directions. The surface mainly covered by mixed clay, sandy clay and sediment, In this area, there are many ponds, lakes and ‘wetlands affected by tidal fluctuation, These water bodies are laid along the large rivers such as Van Uc, Lach Tray, Thai Binh and Hoa rivers. Particularly, the study ‘area has a long shoreline with many estuaries (Thai Binh and Van Uc estuaries) leading to transfer amount of sediment to the Sea significantly. This helps forming the huge polders, mangrove forests or new economic areas such as Tran Duong, Vinh Quang, Tien Hung, Dong Hung, Tay Hung,
“The study area’s river network consists of large main rivers which belong to Red ~ Thai Binh river system such as Luoe, Moi, Hoa, Thai Binh and Van Uc Rivers.
‘Thai Binh River is flowing through Cat Khe and Phu Luong hydrological stations. The river is then divided into wo tributaries including Thai Binh and Rang — Gua Rivers, A segment of Thai Bình tributary flows to Mia River, then merges with Van Uc. Another segment of Thai Binh river right after Mia River is deposited strongly. Dai Thang weir was built on this river to get water for irrigation purpose ‘Another segment of Thai Binh River identified from Quy Cao to the sea becomes a
19
</div><span class="text_page_counter">Trang 25</span><div class="page_container" data-page="25">tremendously and flood controlling capacity of this river is mostly zero. Thai Bình River, a segment from the conjunction of Moi River to the sea, has low velocity and has been deposited by sediment, Currently, the river bed of this river is quite large but the river depth is relatively shallow. The river bed elevation changes from -1.00 m down to -2.50 m, Due to the degradation of the river, the discharge of Luoe River flowing into this river is qui small, This will definitely lead to extreme salt intrusion, ‘Thai Binh River, from the conjunction of Moi River to the sea, plays an essential role in supplying water for Tien Lang district.
Van Ue River has several tributaries such as Mia, Moi, Gua and Lai Vu Rivers. ‘This river divers a small amount of water to Lach Tray River. Van Uc River's length is about 43.5 km, average width of the river is approximately 500-800 m, and river bed elevation changing from -10.00 m down to -16.00 m. The lowest point reaches -47.00 m where located nearby Moi River.
Luoe River is a tributary of the Red River. Luoc River transfers a small amount ‘of water to Hoa and Thai Binh Rivers, meanwhile, the entire water from thị river is transferred to Moi and Van Uc rivers. A segment of Luoc River passing Hai Phong has length of 14 km, the average width of cross-sections here is 300 meters, bed elevation fuctuating frim -8.00 m down to -12.00 m, Luoe river plays a role as a natural border ‘of Vinh Bao (Hai Phong province) and Hai Duong as well as a main source of water supply for Vinh Bao and Tien Lanh districts,
Hoa River is another tributary of Luoc, which defined from Chanh Chu conjunction. The river reaches to the ea throughout Thai Binh estuary. The length of the river is about 37 km, and wide of river bed from 150 - 250 meters, elevation of river bed from -5.00 m down to -7.00 m, Hoa River is a natural border between Vinh Bao district and Thai Binh Province and is a water supply source for Vinh Bao district,
“The study area is located in the southern part of Hai Phong city. The topography of the area is mainly delta, Therefore, climatic and hydrologic conditions here have the characteristics of typical red river delta in general and Hai Phong city in particular.
</div><span class="text_page_counter">Trang 26</span><div class="page_container" data-page="26">‘The study area has the tropical monsoon climate of coastal zone. There are two ‘opposite seasons here. Summer season (South-West monsoon) is from May to October
with high humidity and a ot of rain, Winter season (North-east monsoon) is from
November to March of following year with cold temperature and less rain. Main characteristics of climate of Hai Phong province described below:
« Temperature
‘The temperature in Hai Phong is normally high and suitable with development of annual agriculture, Due to the controlling of pole cieuladon, annually the temperature in Hai Phong is split into different seasons: hot summer has high
in July at Hon Dau, Lowest monthly average temperature reaches 16.3 in January at Phu Lien, Maximum temperature, which was observed in Phu Lien and Hon Dau
Stations [1 jM [mm [iV [V [vt |VH[VHjIX X [XI |XH | Tot! PhuLien |I63 169] 194) 23) 265) 281 |284| 27.7 | 269 247|2L3|I79| 331 HonDan [168] 168|192|228) 27/285] 29| 284|a76 253|223| 19| 236
‘Annual average rainfall is approximately 1520 mm, The spatial distribution of annual rainfall is not too different, Annual yearly total rainfall reaches 1677 mm at Phu Lien, and 1534 mm at Thuy Nguyen, 1544 at Tien Lang and 1514 mm at Vinh Bao, Yearly rainfall at the northern parts is normally higher than the southern parts caused by the directions and effects of typhoons and tropical low pressure once they land deeply. Hence, the maximum yearly infall is usually occurring in the years
</div><span class="text_page_counter">Trang 27</span><div class="page_container" data-page="27">Which affected by typhoons or tropical low pressure. Typically, the maximum rainfall reached 2653 mm in 1973 at Tien Lang, and 2577 mm at Thuy Nguyen in 1973, 2271 mm in 1965 at Vinh Bao and 2298 mm at tien Lang in 1960. By contrast, the year 1991 obtained 826 mm at Phu Lien, and 493 mm was obtained in 1968 at Thuy Nguyen, 686 mm in 2007 at Vinh Bao and 637 in 1991 at Tien Lang.
In the rainy season, the rainfall of August reaches highest proportion of 20.9 % at Phu Lien in comparison with annual rainfall, and similarly 18.6% at Vinh Bao, 196% at Tien Lang and 20.7% at Thuy Nguyen. The maximum rainfall of three ‘months (from July to October) accounts for 50.3 to 53.9 % of yearly rainfall.
In the dry season, the lowest rainfall in July only reaches 0.8 to 1% of yearly rainfall, minimum rainfall of three months (from December to February) accounts for 4.4% of yearly rainfall at Phu Lien, 4.7% at Vinh Bao, 3.9% at Tien Lang, 3.4% at “Thuy Nguyen
‘Table 3.2 Typical average monthly rainfallat stations
Phu Lien station | Vink Baostation | Tien Lang station | Thuy Nguyen station Month | AY€"@e | Proportion | Average | Proportion | Average | Proportion | Average | Proportion Toul | lố7 | 100 | ISHM | 100 | ISM | 100 | l5 | 180
Annually there are about 100 ~ 150 rainy days recorded in Hai Phong. In the winter, there are about 8 to 10 rainy days in a month. In the summer, there are normally 13 to 15 rainy days in a month, Particularly, August has many rainy days and highest rainfall rather than others.
<small>© Wind and storm</small>
~ Wind: The average wind speed was obtained relatively 3.0 mis at stations located in main land and reached 5 to 7 m/s at station located in Islands. The wind direction in
con high and distance from the sea level. Annual wind speed reaches from 33 to 35 mis appearing mainly in typhoon season (July, August and September). The maximum
‘Table 3.3 Typical monthly average wind speed (m/s) at three stations
Stations [1 |H [m [wv [v jvi [vn[vmjix [x [xi [xm [Nam Phutien | 34| 27) 27| 31| 33) a1| 32| 27| 28] 30| s0| 28) 30 HonDaun | 4§| 46) 4a] 47| se] s7| 6| 47| 46} s[a9[ a7) 5 BạchLongVi| S 77| 65] S9| 65] 68| 77] 59| 66| 77] §2| 78] 71
‘Typhoons and tropical low pressures: annually there are about 3 - $ typhoons or tropical low pressures landing into Hai Phong province (about 6 ~ 7 typhoons and tropical low pressures coming to Vietnam), Particularly, 1 or 2 typhoons or tropical low pressures land directly and damage the infrastructures such as dikes, dam as well as liv hoods. Rainfall caused by storms accounts for high rates of total yearly rainfall (about 20 ~ 30%), especially storm rainfall accounts for 50 ~ 60% of total rainfall in August. Once typhoons come to the land, wind speed would be very strong and high Average wind speed during typhoons normally is 30 ~ 40 mís, maximum value could bbe reached 50 ms
3.1.3 Hydrological characteristics
‘There are 9 hydrological stations located in Hai Phong City. Trung Trang and Cua Cam are classified as level 1” stations. However, total flows on Hai Phong's river systems are originated from Red, Thuong, Luc Nam and Cau Rivers, which are tributaries of the Hong ~ Thai Binh river system. These flows are transferred through
2B
</div><span class="text_page_counter">Trang 29</span><div class="page_container" data-page="29">Duong and Luoe river to Kinh Thay and Thai Binh Rivers. So the flow regime of rivers in Hai Phong is pretty similar to the upstream rivers.
Annual flow distribution:
Flows are distributed unequally in a year. The flows in the study prolong from Jun to October, and account for 80% of total flows. The flows in August are maximum, accounts for 24% of total flows. Minimum flow usually appears in March accounting for | — 2,3% of total flows. The flood season spreads in five months. However, the amount of water in this season accounts for 80% of total flows. The dry season spreads in seven months accounting for 20% of tata flows.
Flood flows:
‘The downstream area of Thai Binh river has been affected by flooding from the Duong and Luce rivers originated from the Red river, Cau, Thuong, Lục Nam rivers and depended on the tidal regime of the East sea as well as the topographic conditions of downstream rivers.
~ Duong River is one of the tributaries of Red River. Duong River transfers ‘water from the Red River to downstream rivers surrounding Thai Binh River System. ‘Therefore, the characteristics of Duong River are similar to the Red river. Flood patlern of Duong River and Luoc River is the same hydrograph of Red River with smaller flood amplitude,
~ Luoe River: amount of water from the Red River is transferred to Luoe River accounting for 1/5 to 1/3 of water of the Red River, which is diverted to Duong River. ‘Maximum annual average discharge of Luoe River measured at Trieu Duong station is
~ Cau, Thuong and Lue Nam Rivers are upstream rivers. So they have various characteristics of flooding compering with the Luoc and Duong Rivers. The flood season normally prolongs from the beginning of Jun to the end of September, 1 month earlier in comparison with the Red river. Due to the small river basins, a short heavy rain event can even cause a large flooding.
In the Red river basin, there are some highest rainfall places surrounding Phai Lai (300 to 500 km), In the Thai Binh river system, the highest rainfall places are quite close to Phái Lai (50 to 150 km). So that, flooding from Cau, Thuong and Lue Nam rivers usually reaches Pha Lai earlier than the Red River. The years that extreme
‘The dry flow:
The flow in the dry season is only supplied by groundwater and surface water as well as retention water, which are stored in the end of wet season, On the other hhand, most rivers here are nearby the sea, so the dry flow is depended on the tidal
‘The flows in Cau and Thuong Rivers in the dry season are mostly stored by
‘The discharge of Duong and Thai Binh has been increasingly developing due to the water diversion from upstream reservoirs in Da River as well as river bed change. ‘Therefore, water supply and salt intrusion prevention at the downstream of Thai Binh River have been improved also,
</div><span class="text_page_counter">Trang 31</span><div class="page_container" data-page="31">Water from Duong River is (he main source supplying for the downstream rivers of Thai Binh River system. Amount of water measured at Thuong Cat in the dey season accounts for 66% - 80% of total water in dry season of Thai Binhìs downstream rivers. Similar to the Red river, the dry season normally prolongs 7 months, from November to April of the following year
Water resources of Luoe River: the Red River's water, which is transferred to the downstream rivers through Luoe River, is relatively not much, only accounting for 30% of Duong at Thuong Cat. In the dry season, severe tidal fluctuation from Ba Lat moves back to the upstream that keeps fresh water in river bed longer. So, that is the
Cau, Thuong and Luc Nam Rivers supply small amount of water for the downstream area of Thai Bình. The dry season in those rivers spreads normally longer than the Red river within 8 months, from October to May of following year. Total "water of three rivers is only 1/3 of Duong River. The seasonal distribution of flow of these rivers is unequally and dry flow is mainly supplied by ground water due to
<small>severe evaporation,</small>
fMuctuating. The highest average water level was measured in Van Uc River at Trung ‘Trang (0.58 m), the lowest average water level was measured in Lach Tray River at Kien An (0.01), Therefore, the lowest water level causes troubles for water intake of
<small>nigation system</small>
3.14. Tide and tidal effects in the river mouth
‘The influences of tidal regime play a important role in studying the coastal areas. According to the tidal classification, tidal regime in the Northern part of Vietnam is mainly 24 hours changing from 1.9 to 2.6 meters. From 1972 to 1990, the tidal amplitude is 1.92 meters. The shape of river mouths depended on tidal regime and waves of rivers, The estuaries in the northern part of rivers have triangle shapes đúc to tidal force. In the northern part, river mouths have U shape, Both tide and ‘waves impact on formation of river mouths (Pruszak et al., 2005). Tidal regime plays
</div><span class="text_page_counter">Trang 32</span><div class="page_container" data-page="32">‘an important role in water exchange and sediment transport at estuaries (Allen et all, 1080; Dyer 1986 and Sassi et al, 2011).
Due to the estuaries reaching the Gulf of Tonkin, water level fluctuation at the estuaries is usually similar to tidal fluctuation of the Gulf. The tidal regime here is daily tide, and huge amplitude, which is one of the large amplitudes in Vietnam. In one day, a tidal peak and tidal foot appear with the amplitude of 3.5 to 4.0 meters. The strong tidal period is 11 hours and weak tidal period is 13 hours. The strongest tide and standing tide normally appear in 15 days. Inthe strong period of tide, flows on the Red and Thai Bình River are affected by the Gulf of Tonkin’s tide. Particularly, the dry
‘The average tial water level is normally highest in the beginning of dry season from November to December, maximum value in October and minimum value at the end of January to April, particularly in March. The magnitude of declined tidal regime reaches highest value in December and lowest value in March and April. The ‘maximum amplitude was 3.94 m occurring in 23 Dec 1968,
3.2, Water Demand
‘The study area includes Tien Lang and Vinh Bao districts. The fresh water is supplied for many purposes such as agriculture, aquaculture, industrial zones. and domestics.
3.2.1, Water Demand for Agriculture
Water demand for agriculture is mainly supplied for cultivation, and a small amount of water is for livestock demand, Water supply for agriculture consists of two types of systems such as water storage and gravity. Water demand for agriculture is extracted from surface water of upstream rivers transferring through irrigation system. Based on the investigation of division of Agriculture and Rural development, water for cultivation and livestock is determined as the following table:
</div><span class="text_page_counter">Trang 33</span><div class="page_container" data-page="33">Table 3.4: Total water used for cultivation and livestock in year 2012
Tien Lang system 124,995
Source: Hai Phong PCC, 2015
‘The period of 2020 and 2030:
Vink Bao | 1% [a] ow [wm] we [nn] a] om | om] | om] wo] Am
Tien Lang | MỊ | n@ | s@ | om | 3M | | em | | os [os | ow) ae) 83
Source: Hai Phong PCC, 2015
‘Table 3.6, Water demand of livestock in the period of 2020 and 2030
‘Areas | 1 |Th2jTh3|Th4|Th5 Th6|Th7|ThS|Th9jThI0|ThI|ThI2] Tông 2020
Vinh Bao [9BI]0IS|0BI|OiS]0, otis [ost [aust [ans] tốt | ane | 0BỊ | 178 Tien Lang [arss) aro) ors [orm [orss) w1a9]orss [ors] wiay) 133 | 01 | o1ss | 150
Vinh Bao [ois [aie] on [ons [arm] ars] ors [ai] ans] on [ons | one [ 2p ‘Tien Lang [019] 0H, 018 [oist | ois), ist] o1s9 jars] wisi) 069 | 05 | 01s» | 1x72
Source: Hai Phong PCC. 2015
Surface water from irrigation system is only used for aquaculture. Water supply from Tien Lang accounts for large proportion with nearly 66 million cubie meters (37.6%).
</div><span class="text_page_counter">Trang 34</span><div class="page_container" data-page="34">‘Table 3.7 Water demand of aquaculture in 2012.
2 Tien Lang 22,631
Source: Hai Phong PCC, 2015
In the period of 2020 and 2030
Source: Hai Phong PCC, 2015 3.2.3, Water demand for industry
In the Tien Lang and Vinh Bao areas, there are to industrial zone including Vinh Niem (14,5 ha) and Tien Lang (139,39 ha). Water supply for industrial zones in Hai Phong city was planned in details.
‘Table 3.9 Current status of water use of industrial zones
1 Vinh Niem 14 485 2 Tien Lang 13938 4181
Source: Hai Phong PCC, 2015 3.2.4. Water Demand for Domestic
‘Water supply for domestic is currently from intake sources of irrigation systems. and groundwater constructions. Surface water is the main source of water supply in
2»
</div><span class="text_page_counter">Trang 35</span><div class="page_container" data-page="35">these areas, Ground water for domex is taking a small amount and inclining extremely due to the water table subsidence and salt intrusion,
‘Table 3.10 Water supply for domestic in Tien Lang and Vinh bao districts
SN | SL | §N | SL | SN_| (people)
No. | Distriet | Total
156482 | 1934 | 2.100 32782 109715 3428 | 9335 | l6183
130466 | 1289 | 1.703 | 27.653) 92.904 | 3.173 (10133) T396,
Source: Hai Phong PCC, 2015 In the period of 2020 and 2030:
‘Table 3.11 Water demand of domestic in the period of 2020 and 2030
Source: Hai Phong PCC, 2015 3.3. Water Exploitation and Utilization Issues
‘Management and operation of the system:
‘The hydraulic works of the irrigation system was built since 1970s, 1990s and 2000s, The human resources for system operation is too large and unproductive. The staffs for management and operation are 100 up to 200 people for each system. The equipment of systems is too old and backward as well as is not suitable for ‘management requires. Lack of information of water level and salinity, etc in order to serve the operation and management of the systems.
‘The hydraulic works have not been maintained, and repaired regularly, so that water intake is not productive and effective, In addition, due (o the urdimentary ‘method of operation processes, so the systems are not running 100 percent. B
</div><span class="text_page_counter">Trang 36</span><div class="page_container" data-page="36">the canals, chanels and streams in these areas have been deposited and penetrated progressively causing unproductive water transfer,
Water storage:
Although, the income water in the study area is very huge, but most rivers have high sediment volume, or salt intrusion problems. Therefore, water here cannot supply for socie-economic demands. It is only used for other purposes such as navigation, transportation and tourism. Water supply for socio-economic development is mainly extracted throughout 5 irrigation systems. At some points in months and days, the ‘water level is very low causing the gravity system is not working. So that, the pumping
Water quality
Due to the location of rivers in th study area, most river here are progr sively affected by salinity intrusion. 1% of salinity appears mostly on the hydraulic works within 10 hours/day and 10 days/month. Alternatively, the turbidness of rivers is very high. Average turbidness is approximately 15 NTU. This will probably reduce the
“The chapter presents the natural conditions, climatic characteristics of the study ‘area as well as the population characteristics, economics and society. The water demand and management are also discussed in this study. Although, the income water in the study area is very huge, but Thai Bình river has high sediment volume, or salt intrusion problems, So, water here cannot supply enough [or socie-economic demands,
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</div><span class="text_page_counter">Trang 37</span><div class="page_container" data-page="37">In this study, according to the research objectives, the methodology consists of data collection survey, filed work and modelling. The method of data collection survey and method of field work will conduct the objective 1. Meanwhile, Objective 2 and 3 will be obtained by the method of modelling.
‘The methodology used in this study will be expressed in detail as the below flowchart
Objective 1
lo implement Field surveying Method of from detailed plan fieldwork
To analyze and process
Objseive2 «——|
Objective 3 «—| Building information systems
‘Writing the report
Figure 4.1: The research flowchart
</div><span class="text_page_counter">Trang 38</span><div class="page_container" data-page="38">4.1. The MIKE 11 Model
The MIKE 11 model uses an implicit and finite differential mathematical scheme to compute unsteady flow in rivers and floodplains. “In the model, a river network
Following assumptions were considered for the modeling (DHI, 2007a).
The water is incompressible and homogeneous (i-., negligible variation in density).
“The bottom slope is small, thus the cosine of the angle it makes with the horizontal may be taken as 1. The wave lengths are large compared to the water depth, assuming
‘The flow is sub-critical (a super-critical flow is modeled in MIKE 11; however, more restrictive conditions are applied).
4.1.1. Governing Equations
Mass and momentum conservation equations are used for the mathematical expression of gradually varied, unsteady flow in open channels. Two governing ‘equations for unsteady open channel flow are well known as Saint Venant’s equation system, The model was developed based on these principles. It uses the unsteady free surface flow equations of continuity and momentum to find the discharge and water level in each cross-section,
‘The continuity equation or mass conservation equation is:
Equation 4.1
Equation 4.2
3
</div><span class="text_page_counter">Trang 39</span><div class="page_container" data-page="39">order, partial differential equations of the hyperbolic type. The transformation of
“A simulated segment linking two nodes possesses average geometric and hydraulic characteristics of the actual channel section. A frictional co-efficient and inertial force exists between to nodes of a river segment. Inflow and outflow of the node control the storage in a node. A positive (+) sign and a negative sign are implied for inflow and outflow respectively. Nodes are coded by positive integers from 1 to NN which is total number of nodes in the river network. The constraint equations at the confluence of river tributaries are defined as follows:” (Dang , 2010, p. 107)
Equation 4.3
4.1.2. Methods used in the performance evaluation
‘The level of accuracy and reliability of the model depend on the assessment of the model performance, Both graphical and statistical comparison between simulated and measured hydrographs are recommended by American Society of Civil Engin
performance evaluation. Firstly, in order to assess the model performance evaluation, 1993). The MIKE 11 model provides both graphical and numerical
</div><span class="text_page_counter">Trang 40</span><div class="page_container" data-page="40">‘graphical comparisons between modeled and measured hydrographs were done, For Sutcliffe the statistical assessment, this study followed on evaluation of Nas
efficiency (Nash & Sutcliffe, 1970). The equation of Nash-Sutcliffe efficieney is
NSE Equation 4.5
ge the observed data
nthe simulated data
a sample size.
“The Value of NSE lies between -2 to +1, The value I indicates a perfect match between measured and simulated data. Model performance is perfect, if values of Nash-Suteiffe efficiency range from 09 to 1. Model performance is good and acceptable, ifthe values range from 0.8 to 0.9 and 06 to 0.8
4.2. Mike 11 Model Set-up
Within the scope of the thesis study, the author has inherited the input data from the National Key Laboratory of River and Coastal Engineering and Institute of
4.2.1. Input data
4.2.1.1. River network and model schematization
‘The Red and Thai Binh river system is a very complicated network with many large basins such as Da, Thao, Lo rivers in the upstream; and huge river delta in the downstream as well as dense river intensity. The Red River is connected with Thai Binh river system by Duong and Luoc rivers. The Red River's flow reaches to the
35
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