Tóm tắt Luận án The research on determining optimal size and layout of detetion pond for the mixed urban and agricultural basins

THUY LOI UNIVERSITY 
LUU VAN QUAN 
THE RESEARCH ON DETERMINING OPTIMAL SIZE AND 
LAYOUT OF DETETION POND FOR THE MIXED URBAN 
AND AGRICULTURAL BASINS 
Major: Planning and management of water resources 
 Code : 62-62-30-01 
THE ABSTRACT OF DOCTORAL THESIS 
HANOI, 2015 
MINISTRY OF EDUCATION AND 
TRAINING 
MINISTRY OF AGRICULTURE 
AND RURAL DEVELOPMENT 
The thesis was completed at the Thuy loi University 
Supervisors1: Assoc. Prof. Dr Tran Viet On 
Reviewer 01: Prof. Dr. Duong Thanh Luong 
Reviewer 02: Prof. Dr.Tran Huu Uyen 
Reviewer 03: Dr. Nguyen Van Tuan 
The thesis will be presented to the Doctoral Evaluation Council at Room 123-A1 
buiding, Thuyloi University. 
.... 
.... 
Time of presentation: . 
If you would like to get more information on this thesis, please feel free to visit: 
- The national Library 
- Thuyloi University Library
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INTRODUCTION 
1. The necessity of thesis 
In recent decades, due to the demands of the development, constructing the 
urban areas and industrial zones have shifted the soil structure of many 
agricultural regions to urban - agriculture mixed regions. This change has 
increased flooding in these areas. Using detention pond to regulate stormwater 
and reduce flooding is an effective solution. However, there are no researches on 
the effects of detention pond to the construction cost of the drainage system for 
the mixed areas. Thus, the theme: "The research on determining optimal size and 
layout of detention pond for the mixed urban and agricultural areas" very 
meaningful to reality and science. 
2. Objectives 
Proposing a methodology to determine optimal size and layout of detention pond 
to reduce the construction cost of the drainage system for the mixed areas. 
3. The scope of work and object of study 
The thesis focused on determining optimal size and layout of detention pond to 
reduce the construction cost of the drainage system for the mixed areas, applying 
to the Western Hanoi. 
Object of study: the drainage system for the mixed areas, applying to the 
Western Hanoi. 
The scope of work: 
- The optimal size and layout of detention pond to reduce the construction 
cost of the drainage system for the mixed areas in terms of ditermining 
topography, ground, slope of canal as well as location of constructions. 
- Regardless of sewage or water quality as well as other costs such as 
operating costs and maintenance of drainage system. 
- Applying to the western Hanoi. 
4. Research methods and approaches 
4.1. Approaches: Approaching the system, inheriting available researches. 
4.2. Research methods and used techniques 
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Inherited methods, modeling and simulation methods, analysing system and 
optimization, statistical methods. 
5. Scientific and practical significance 
Scientific Significance: The thesis provides scientific methodology for 
determining the optimal size and layout of detention pond to reduce the 
construction cost of the drainage system for the mixed areas. 
Practical Signigicance: The thesis proposed the percentage of area and form of 
rationl layout of detention pond in the Western Hanoi. This result can be applied 
in planning of detention pond for the Western Hanoi and other areas with similar 
conditions. 
6. New contributions of the thesis 
1. This thesis provided a scientific method to determine the capacity and layout 
form of detention ponds for the mixed urban and agricultural drainage to 
reduce the construction cost. The new method includes: constructing 
objective functions, identifying components of the objective function, 
solving optimization problems, suggesting a decision alternative (i.e. instead 
of proposing and calculating each of available alternatives in detail, these 
alternatives were compared, and then the best alternative was selected). The 
new method overcomes a limitation of the existing method which limits 
quantity of alternatives, hence the new method is considered more 
appropriate than the old one. 
2. The thesis has applied the new method successfully for a case study- a basin 
in Western Hanoi. This area is currently being urbanized, and industrialized 
with the combination of agricultural land and urban land. The thesis used 
SWMM5.0 (Storm Water Managament Model of EPA, USA) to analyze 
and evaluate 500 options including centralized detention ponds at the 
headworks or decentralized ponds at major channels and at minor channels. 
The results show that: i) For this study area: The appropriate ratio of 
detention pond area to total drainage basin area fluctuates from 2% to 3.82% 
depending on two factors: (1) layout form of detention ponds (i.e. 
decentralization or centralization). The more dispersive the detention ponds 
are, the higher the ratio is; (2) land acquisition cost. The more the land 
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acquisition cost is, the smaller the ratio is and vice versa; ii) With the same 
ratio, the more dispersive the detention ponds are, the less the land 
acquisition is and vice versa. This result (first time) proved (through specific 
data) the effectiveness of the motto "spraying water, burying water" 
proposed long time ago by water resources experts of Viet Nam. 
The research results can be applied for other similar drainage areas. 
7. The layout of thesis 
There are three main chapters: 
Chapter 1. Overview of detention pond, effect of detention pond to drainage 
system for the composite areas. 
Chapter 2. Methodology and research tools. 
Chương 3. Researching and determining the optimal size and layout of 
detention pond for the Western Hanoi. 
CHAPTER 1. OVERVIEW OF DETENTION POND, EFFECT OF 
DETENTION POND TO DRAINAGE SYSTEM FOR THE COMPOSITE 
AREAS 
1.1. The function of detention pond 
1.1.1. Terms 
The detention pond is a terminology standing for lowlands, valleys where have 
water storage capacity (temporary or permanent), formed in natural or artificial 
conditions. The system is responsible to drain simultaneously for either 
agriculture and urban area called the drainage system for the mixed areas. 
1.1.2. The function of detention pond 
The detention ponds in drainage system simultaneously perform multiple 
functions such as regulating stormwater, reducing flood, storing water for 
irrigation, aquaculture, improving the microclimate, creating good ecological 
environment. 
In this research, detention pond (called HDH) focuses only on the function of 
regulating stormwater and reducing flood. 
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1.1.3. The connecting forms between detention pond and chanel. 
There are two connecting forms: detention pond is on channel and detention 
pond is beside of channel. (1) Pond on channel is construction connected from 
pond to channel by spillway, culvert or channel or combination between channel 
and spillway, channel and culvert. (2) Pond beside channel is part of channel 
extended with function of regulating water. 
1.2. Overview of using detention pond 
1.2.1. On the world 
Detention pond used to reduce flood in urban areas have built widely since 06’s 
of 20th century all around the world. However, the uneven contribution of pond 
area with total drainage area is diffirently divieded among cities as well as 
continents. 
1.2.2. In the Vietnam 
The detention pond in urban drainage system have area ratio from 1% to 5%, 
most natural lakes, and scattered distribution. Some detention ponds use less 
efficient due to the location, area ratio, capacity, operation or connecting system 
between pond and channel. 
1.3. Overview of researches on detention pond 
1.3.1. On the world 
There have been many researches on the effect of detention pond to the flooding, 
environment and landscape ... Some studies which have figured out the 
approaching method by using detention pond to store the rainfall for other 
purposes is very effective either technique and economy. Some studies shown 
that the concentrating pond reduce peak discharge and flooding better than 
dispersing pond. 
1.3.2. In the Vietnam 
Some studies on sustainable drainage have considered the detention pond under 
the aspect of dispersion, rainfall reducing at source (stored in households and 
increased permeability). The studies about the influence of the detention pond to 
the drainage headworks were also considered. In addition, studies of other fields 
(environment, landscape, ecology) were also announced. 
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In conclusion, either worldwide and Vietnam doesn’t have any research on 
relationship between size and layout form of detention pond to the construction 
cost of the drainage system for the composite areas. 
1.4. Conclusions of chapter 1 
The results of research show that: 1) Area ratio of detention pond in cities on the 
world and in the Vietnam are very different. 2) Most of the research focused on 
the function of environmental improvement and storing water for many 
different purposes. 3) Concentrating pond has good efficiency for reducing the 
peak discharge, flooding area and the flooding depth depends on the scale and 
layout form of detention pond. 4) Detention pond in agricultural drainage system 
have researched at the simple level: aquaculture pond, storage water in fields. 5) 
Effect of detention pond to headworks is very clear. 
There are no researches on relationship between size and layout form of 
detention pond to the construction cost of the drainage system for the composite 
areas. 
According to above reasons, the thesis: “The research on determining the size 
and form of rational layout for the composite area” is sponsored to research. 
CHAPTER 2. METHODOLOGY AND RESEARCH TOOLS. 
2.1. The detention pond in the drainage system 
2.1.1. The detention pond in the urban drainage system 
The detention pond is one of terms of urban drainage system. The detention 
pond originated from either nature or artificiality is distributed in residential 
areas or park to store rainfall, reduce flooding, improve the environment and 
provide water for irrigation. 
2.1.2. The detention pond in agricultural drainage system 
The detention ponds in agricultural drainage systems are natural ponds or lakes 
existing before headworks were built. The natural ponds are sparsely distributed 
and the artificial pond has function on aquaculture or irrigation. These detention 
ponds have function to store rainfall, reduce the peak discharge for downstream 
constructions, and provide water for irrigation. 
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2.1.3. The detention pond for composite areas 
The drainage system for composite area includes simultaneously drainage 
construction for urban areas and for agricultural areas. Constructions in drainage 
system are characterized by incharge area is urban or agricultural. 
2.2. Making the problem to determine the size and layout of detention pond 
Figure 2.7. Drainage system layout for the composite areas 
The problem is applied to the composite areas. The initial conditions of the 
problem stated that the drainage ground, land using and infrastructure need to be 
planned in the researching area (determing location of the drainage headworks, 
regulating culvert and canals). Therefore, the detention pond area may be 
reached to a certain rate. 
Requirement: Determing the size and layout form of detention pond in order to 
minimize the construction investment cost and ensure no waterlogging 
corresponding the design storm. 
2.3. Method 
2.3.1. Proposing the sequence to solve the problem 
a. Traditional method 
It is based on experience, by calculating and direct comparision, the designers 
give out the best appropriate method. The steps of solving will be shown in the 
figure 2.9. The advantage of this method is easy to implement and the 
disadvantage is that the calculation volume is too large and the result depends 
subjectively on the proposing person. 
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b. New method 
The author proposes a new method to determine the size and form of rational 
layout for detention pond (Figure 2.8) including building objective function, 
solving the optimization problem by regression method, proposing a reasonable 
solution. 
 Figure 2.8. New method Figure 2.9 Traditional method 
(Diagram of determining steps of the reasonable layout of the detention pond) 
The basic advantage of this proposed method is to increase the considered cases 
(more than 500 cases), regardless of the experience of proposer. Thus, the 
rationality of the proposed method is very high. 
2.3.2. Facility to determine the size and layout form of detention pond 
The construction area should take advantage of the natural ponds and farmland 
and are not coincided to the technical infrastructure already planned. 
Proposing some different 
solutions: (canal, 
Establishing methods (hydraulic, 
hydrological calculating – 
determining designing flow rate and 
method scale by modelling) 
Establishing regression 
function 
Studing basin characteristic: 
Topography, geology, land 
using 
Solving multi-objective 
optimization problem (using 
empirical planningmethods to 
solve) 
Proposing selected method 
Proposing some solutions: 
(channel, detention pond) 
Determining the designing flow 
rate of each method 
 Economy, technical calculating of 
each method 
Studing basin characteristic: 
Topography, geology, land using 
Comparing methods, determining 
the reasonable method 
Proposing selected method 
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The calculating scenarios are created from the combination of size and layout 
form of the detention ponds (concentrated or dispersed) in the determined region 
under the plane containing thescale and layout form axis (Figure 2.10). 
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Figure 2.10. The determining method of layout form scenario 
2.3.3. Determining the size of the drainage system in scenarios 
After proposing the scenarios on size and layout of detention ponds, it is period 
to determine the construction scale in system by following steps: 
1st Step: Determining the preliminary dimensions of channels, pumping stations 
according to the current regulations, namely follow to the formula in TCVN 
7957: 2008, TCVN 4118-85. 
2nd Step: Using Storm Water Management Model 5.0 (SWMM 5.0, EPA USA), 
to simulate and to check the system determined from the 1st Step. This problem 
suggests for the urban drainage system and appling “on-farm detention pond” 
method for the agricultural area. The calculating result of on-farm detention 
pond method is outflows and they are entered into the SWMM 5.0 model as 
inflows at Nodes. 
2.3.4. Establishing the objective function and the constraint conditions 
a. General objective function 
General objective function for reasonable  ... rature on drainage plan for the west of Hanoi, the drainage basin 
is divided into 03 drainage headwork. The detention pond area selected by 
percentage of drainage area ranged from 0% to 6%. About detention pond layout, 
this study considered 03 scenario groups: (1) pond concentrated in the drainage 
headwork, (2) pond distributed along the main channel (PT1), (3) pond 
distributed along the main channel and branch channels (PT2). 
a. The scenarios of the detention pond concentrated at the drainage headwork 
(TT) 
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The author proposes 12 scenarios of the detention pond that concentrated at the 
drainage headwork and had the same area ratio in the 03 drainage headworks. 
The area ratio of detention pond ranged from 0% (no pond) to 6%. Otherwise, 
the authorlso proposes 24 scenarios of the different detention ponds in every 
drainage headworks. Totally, 36 scenarios were considered. 
b. The scenarios of the distributed detention pond 
* The scenario of detention pond distributed along the main channel (PT1) 
including 11 scenarios, each scenario has 11 locations of detention pond.. 
* The scenario of detention pond dstributed along the main channel and branch 
channels (PT2) including 11 scenarios, each scenario has 38 locations of 
detention pond. 
3.5. The result 
3.5.1. The results of simulation of the flow corresponding to each scenario 
The discharge in calculating or modeling is the average value in hour. According 
to designing standard, this value will be used in designation. 
3.5.1.1. The scenarios of the detention pond concentrated at the drainage 
headwork (TT) 
Figure 3.10. The relationship between 
upstream discharge and the detention pond 
area 
Figure 3.11. At Lien Mac inflow when the 
detention pond area changing 
At the upstream, discharge decrease when the pond area increases. The 
reduction is smaller and smaller (Figure 3.10 and 3.11). The peak discharge 
summary of the headworks reaches to minimum at TT666 (pond ratio 6%). 
When the pond area ratio is different at the headworks, the headwork discharge 
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summary reaches to minimum corresponding to pond ratio 5.3% (as scenario 
TT664). 
3.5.1.2. The scenarios of the distributed detention pond 
The calculation results for the scenario group (PT1) and (PT2) present the total 
peak discharge at upstream and total peak discharge at channels are minimum 
when the pond ratio is 4.35% (as scenario PT1-6) and 4.58% (as scenario PT2-6) 
corresponding to the scenario groups PT1 and PT2. 
3.5.1.3. Comparision between scenarios of concentrated and distributed 
detention pond 
The comparision is shown in the following diagram: 
Figure 3.15. The diagram of relationship 
between upstream discharge and the 
detention pond area 
Figure 3.16. The diagram of 
relationship between the total of peak 
discharge and the detention pond area 
The headwork peak discharge reduces in all 3 scenario groups (TT, PT1 và PT2). 
In which, the scenario of distributed detention pond along the main chaneel and 
branch channel (PT2) gave out the minimum value (figure 3.15). 
The diagram 3.16 has shown that the peak discharge of the channel system 
corresponding to scenario (TT) unchanged (horizontal line). On the other hand, 
both of the scenarios (PT1) and (PT2) decreased strongly. Especially, the 
scenario of pond distributed along the main channel and branch channels have 
strongest reduction (the pink line) 
Summary: Regulating effect of the pond depends on not only the pond scale, but 
also the form layout (concentrated or distributed). Considering overview of the 
system, if the distribution of detention pond is more and more large, the effect of 
peak discharge is more and more increase. 
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3.5.2 Applying the regression function to determine the reasonable scenario of 
detention pond for the west of Hanoi 
Applying the established regression functions in the previous parts to determine 
the reasonable scenario of the detention pond, inluding: 
3.5.2.1. The scenarios of the concentrated detention pond 
a. In case of 100% agricultural land (TH1) 
Figure 3.24. The graph showing the 
relationship between the detention pond 
area and the construction investment cost 
of work items corresponding to structural 
plan (GTT1) 
Figure 3.25. The graph showing the 
relationship between area ratio and 
construction investment cost of whole 
system 
Remark: GTT1: The box channel grade 3, reinforced main channel, headwork 
and detention pond were built; GTT2: The round channel grade 3, reinforced 
main channel and detention pond was built; GTT3: The box channel grade 3, 
channel grade 1 and 2 dredging only and headwork and detention pond were 
built. 
The evolution trend of the construction cost of each work item is shown in figure 
3.24. Considering the figure 3.25, the graph presented to 03 form structures 
forms is parallel with each other and every line existes a minimum point with the 
pond area ratio of 2.5%. 
From the calculated results of 36 scenarios, the proposal on form layout of 
detention pond that concentrated in the headwork in the western system of 
Hanoi when area clearance of 100% is agricultural land achieve the reasonable 
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value (2.5% are arranged for all 03 drainage headworks, 2.91% are unevenly 
arranged on drainage basin,) (Lien Mac 4%, Thai Yen 2%, Yen Nghia 2%). 
 b. In case of 85% agricultural land ( TH2) và 70% agricultural land (TH3) 
After calculating with 36 scenarios of layout form with 03 structural forms 
corresponding with 02 cases, it is totally 216 calculating cases, comparing the 
calculated results, it can be concluded as follows: 
For the drainage system in the west of Hanoi while unit prices of site clearance 
is different (TH2, TH3) and the layout form of detention pond is concentrated at 
upstream, the construction investment costs have minimum values while area 
ratio was 2% (evenly arranged for all 03 drainage headworks), was 2.91% 
(unevenly arranged: Lien Mac 4%, Thai Yen 2%, Yen Nghia 2%). Therefore, in 
the case detention pond concentrated in the headwork, reasonable scale of the 
detention pond is 2% (arranged for all 3 headworks), 2.91% (unevenly arranged 
for all 3 headworks). 
3.5.2.2. The scenarios of the distributed detention pond 
a. In the case of 100% agriculture land ( TH1) 
The calculating results for 02 scenario groups of distributed pond be shown as 
figure 3.25 
a/ The distributed pond PT1 b/ The distributed pond PT2 
Figure 3.26 and 3.27. The graph showing the relationship between area ratio and 
construction investment cost of whole system 
According to the figure 3.26 and 3.27, the graph have 03 parallel corresponding 
to 03 strutural forms, each line exists a minimum point (minimum value) on 
construction investment costo n the whole system. In the scenario of distributed 
pond in the main cannel (PT1), the construction investment cost correspond to 
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area ratio 3.62% considering on the scenario of distributed pond in the main 
cannel (PT1) and 3.82% considering on the scenario of distributed pond in either 
main cannel and sub-channel (PT2). 
b. In the case of 85% agricultural land ( TH2) and 70% agricultural land ( TH3) 
The calculating results on TH2 and TH3 is similar to TH1. The trend of 
minimun point of total construction investment coston whole system move close 
to the origin when the site clearance cost increase. 
In conclusion: For the west of Hanoi when arranged the distributed pond in the 
main cannel, the minimum point of construction investment cost (ĐTXD) in the 
whole system is at the location of 3.62% of pond area corresponding to TH1, 
3.26% corresponding to TH2 and 2.90% corresponding to TH3. When 
arranging the distributed pond on main or sub- cannel, the minimun cost of 
construction investment costo n whole system is 3.82% corresponding to TH1, 
3.05% corresponding to TH2 and 2.67% corresponding to TH3. 
3.5.2.3. Comparision between each scenarios of pond layout 
Chosing one type of structural form to compare: 
Figure 3.28. The graph showing 
relationship between area ratio and 
construction investment cost at the 
headwork 
Figure 3.29. The graph showing 
relationship between area ratio and 
channel construction cost 
For the headwork: The construction investment cost of the 03 scenarios stands 
separatly proving the layout form (concentrating or distributing) greatly affect to 
the construction investment cost. For the cost of clearance, this effect is 
negligible (Figure 3.28). 
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For channel systems: The separation of graph present the construction 
investment cost of 03 groups (100%, 85%, 70% of agricultural land for 
compensation) separately. It is easy to comment that when the compensation 
increases, the construction investment cost increase. The detention pond is more 
and more diffuse, the construction cost derease. 
The total construction investment cost of all work items corresponding to 
structural form exist a minimum point. This is value of the reasonable scale of 
the detention pond. 
3.6. Conclusions of chapter 3 
The results in chapter 3 showed that there is a close relationship between 
construction cost and detention pond’s size or layout form. In general of the 
same size, if the detention pond distribute increasingly, the construction cost is 
more and more decrease and vice versa. Inaddition, the reasonable area of 
detention pond (corresponding to the minimum point of construction cost) 
depend on unit price of site clearance. When compensation unit price increase, 
the area ratio tends to reduce and vice versa. 
CONCLUSION AND RECOMMENDATION 
I. Conclusion 
The thesis reviewed the status of distribution and use of detention pond as well 
as the relevant studies in VietNam and in the world. The thesis also pointed out 
the urgency, novelty of research problems in the thesis, not overlapping with the 
studies which have been published previously in Vietnam and abroad. 
The thesis developed a method to solve the problem of determining rational size 
and layout of detetiom pond to reduce the construction costs of the mixed 
agricultural - urban region. The method includes: identifying the calculation 
steps, building the objective function, specifying the objective function 
components. The thesis also selected the mathematical model Storm Water 
Management Model (SWMM) 5.0 of EPA, USA to simulate rainfall-runoff for 
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urban areas, and the used “on-farm reservoir” model to calculate outflow from 
the agricultural areas. 
SWMM 5.0 was validated corresponding to the study area based on observed 
data. The validation results have determined the model parameters in the study 
area. These parameters were used for the next calculations of the thesis and 
certify the reliability of the model in simulating hydrologic - hydraulic process 
for the drainage system in western part of Hanoi. 
The thesis has developed the objective function for study basin – the West of 
Hanoi, the components of the objective function are calculated and determined 
corresponding to price of construction in at the fourth quarter of 2013. The 
regression relationship between investment costs and discharge between the 
construction cost of the pond and pond area were calculated for 03 cases of 
clearance, the regressions were achieved in validating the probability of mistakes 
by Eview 6.0 software. 
This is a new research methodology considering the whole system in terms of 
hydraulics, hydrology and economics. The method presented in this thesis can be 
applied to other areas with similar conditions, and is probably extended to 
establish operation procedures reasonably or design and upgrade drainage 
system including head channel system and detetion pond. 
Detetion pond only regulates peak flow for works behind pond, peak discharge 
decrease rate is proportional to the area of the pond, pond separately distributed 
have more effective regulatory than clustered at headworks because many work 
items are reduced peak flow. 
The calculation results showed that the option having the lowest total investment 
cost of construction depends on the smallest construction unit prices, unit costs 
for site clearance compensation. When compensation cost is higher, reasonable 
plan is tended to small scale detetion pond. 
Cost of construction depends on the construction unit prices, clearance unit 
prices, forms and reasonable detetion pond distribution will vary between 
localities. 
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II. Recommendation 
Detetion pond provides many benefits in addition to regulating stormwater to 
reduce flooding such as improving the environment, creating recreation centers, 
entertainment, and sports communities. Accordingly, for urban areas, industrial 
zones, when considering the construction of detetion pond, it is necessary to 
consider the overall interests of the detetion pond to the area to confirm the real 
benefits of the project. 
III. Limitation of the Thesis 
The thesis considered the pond located nearby the canal, rainwater flowing into 
and out of the pond in term of gravity, but not considered yet the pond located 
on the canal, and pond with regulation works. It is necessary to study cases 
having agricultural land in different clearance scenarios between work items in 
the system. 
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PUBLICATIONS OF THE AUTHOR 
1. Luu Van Quan, Tran Viet On (2015), Application of a method for 
determination of location and appropriate scale of a detention pond - a case 
study: drainage system in Western Hanoi, Science and Technology Journal of 
Agriculture & Rural Development, Issue 18-2015, pp 49-56. 
2. Luu Van Quan, Tran Viet On (2015), A method for determining area (or volume) 
of a stormwater detention pond for a new urban area, will be published in Journal of 
Water Resources & Environmental Engineering, Issue 51-2015. 
3. Luu Van Quan, Tran Viet On (2015), Optimal construction cost for urban 
drainage systems: A case study in a drainage basin, Western Hanoi, Journal 
of Water Resources & Environmental Engineering, Issue 48/3-2015, pp 92-98. 
4. Luu Van Quan, Tran Viet On (2014), Relationship between detetion pond 
areas and pond effluent flows in an urban drainange system: Case study of 
Dam river basin in drainage system Hanoi, Journal of Water Resources & 
Environmental Engineering, Issue 47/12-2014, pp 03-08. 
5. Luu Van Quan (2014), The research on the optimum layout of detention pond 
is to reduce the urban drainage system's scale (applied to the drainage 
system of the west of Hanoi), the university - grade scientific research. 
6. Luu Van Quan, Nguyen Tuan Anh (2013), Situation of using detetion pond in 
storm water drainage system in some cities of the Northern delta, Viet Nam, 
Journal of Water Resources & Environmental Engineering, Issue 41/6-2013, pp 16-
20.