Nhue River Sub-basin, Vietnam

Indexed in Scopus Compendex and Geobase Elsevier, Chemical Abstract Services-USA, Geo-Ref Information Services-USA, List B of Scientific Journals, Poland, Directory of Research Journals www.cafetinnova.org ISSN 0974-5904, Volume 06, No. 05(01)

October 2013, P.P.1111-1119

Numerical Modeling in Water Quality Management for Rivers – Case Study of the Day/ Nhue River Sub-basin, Vietnam Q. T. DOAN1, Y. C. CHEN 1 AND P. K. MISHRA2 1

Department of Environmental Engineering, Da-Yeh University, Taiwan Department of Wood Science, Mendel University in Brno, Czech Republic Email: [email protected], [email protected], [email protected] 2

Abstract: In this study attempts were made to apply Mike 11 water quality model to estimate existing water quality conditions and transmissibility of pollutants from discharge source in Day/Nhue River basin. Along with it, real time measurements were also done for calibration model from November 2005 to April 2006. The Day/Nhue River, sub basin located to the northeast of Vietnam was considered for study. Based on Mike model it was found that pollution level in Nhue River are highest, especially near Hadong Bridge and location from Thanhliet Dam to Cuda is the most polluted and measured values were in good agreement with it (BOD value in November 2005 was about 8598mg/l , which is twice of the acceptable criteria ). Nevertheless, collected date can be utilized to review and consider while planning, licensing or regulating the wastewater discharge permission on this basin. Keywords: Day/Nhue river sub-basin, Water quality model, MIKE 11, Wastewater discharge permission. 1.

Introduction:

River systems carry along loads of particulate and dissolved matter of natural and artificial origin. The quality of river water is affected by lithology of basin, climatic, anthropogenic and environmental factors (ICEM, 2007; JICA, MA and RD, 2004; KEPB, 2009; Huang, et al., 2009). Water quality models are utilized to simulate stormwater (EPA, 1997), surface and underground water pollution (Busteed et al., 2009), land use effects (Carpio and Fath, 2011) and wastewater treatment processes. These model components (like the underlying processes) can be very complex when simulating the cycle of pollutant build-up, wash-off and impact. Water quality models have similar components as hydrologic and hydraulic models and often require calibration to produce credible predictions (GSMM, 2003). MIKE 11, which is developed by the Danish Hydraulic Institute (DHI), is a tool for modeling conditions in rivers, lakes, reservoirs, irrigation canals and other inland water system. MIKE 11 consists of modules that allow users to specify the type of hydrologic process to simulate. It is a menu-driven model configured with a core module that includes a menu for data handling and program execution. The model includes modules to handle various data types. One of these modules is the water quality module, which is an extension of the transport-dispersion module and is utilized to simulate the reaction processes of multi compound system and models a variety of biochemical interactions processes,

including BOD, DO computation and simulation of nutrients, macro-phytes and plankton. MIKE 11 requires hydrologic parameters, river cross section, floodplain topography, discharge and water level records, measured or simulated rainfall for the purpose of water quality modeling MIKE, 2007 (DHI, 2007a; DHI, 2007b; DHI, 2007c). A flowchart of research procedure is constructed as shown in (Fig. 1). 2.

Materials and Methods:

2.1 Study site: This research focused on Day/Nhue River sub-basin located to the Northeast of the Vietnam map (Fig. 2). The Day/Nhue sub-basin has a total area of 6,965.45 km2 and covers six provinces including: Hatay, Hanam, Namdinh, Ninhbinh, Hanoi and Hoabinh. The sub-basin has a wet-hot monsoon-tropical climate with dry-cold winter and rainy-hot summer. Annual average temperatures range from 24-270C. Annual average rainfall is 1,500-2,200 mm. These Rivers severs as a water supply to the Hanoi which is the capital of Vietnam. The initial flow value at Lienmac on Nhue River and Batha on Day River were the average day values on dry season November 2005 to April 2006. The water demand on the river was the water quality standard Class A (the water for industrial purposes) (TCVN, 2006). The water quality parameters were reviewed include BOD (representing organic pollutants); TSS (representing physical pollutants); N and P (representing nutrient pollutants).

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Numerical Modeling in Water Quality Management for Rivers – Case Study of the Day/ Nhue River Sub-basin, Vietnam 2.2 Mathematical model: 2.2.1 MIKE-NAM: NAM represents various components of the rainfallrunoff process by continuously accounting for the water content in four different and mutually interrelated storages. Each storage represent different physical elements of the catchment. NAM can be used either for continuous hydrological modeling over a range of flows or for simulating single events. The NAM model can be characterized as a deterministic, lumped, conceptual model with moderate input data requirements. A description of the classification of hydrological models is given in (Abbott and Refsgaard, 1996). Refsgaard and Knudsen (1996) compare a number of different types of hydrological model, including the NAM model, in terms of both data requirements and model performance. The NAM model is a well-proven engineering tool that has been applied to a number of catchments around the world, representing many different hydrological regimes and climatic conditions. The model structure is shown in (Fig. 3). 2.2.2 Hydrodynamic model (HD): Mathematical model are useful tool in analysis of river flow or hydraulic structures. In this paper, according to high performance of one-dimensional model in river studies, solve the equations governing the river flow has been considered. One-dimensional equations governing the river flow are known as Saint-Venant equations (Shooshtari, 2008). Mass conservation

Q A  q x t

(1)

 Q2     A  Q h gQ Q    gA  0 t x x C 2 AR

(2)

Where, Q: discharge; A: flow area; q: lateral flow; h: stage above datum; C: Chezy resistance coefficient; R: hydraulic or resistance radius;  : momentum distribution coefficient. The solution of the equations of continuity and momentum is based on an implicit finite difference scheme developed by (Abbott and Ionescu, 1967). The finite difference scheme used in MIKE 11 (6point Abbott scheme), allows Courant numbers up to 10-20 if the flow is clearly sub-critical (Froude number less than 1). A graphical view of this method showed as below (Fig. 4). As we can see at n+1/2 step the model bring data from steps n and n+1, so unknowns will obtain

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simultaneously for each time step. MIKE 11 model is fully implicit method to solve the problem and usually there is no limitation about computational (Price, 2009). 2.2.3 Water Quality (WQ): It estimated the discharge and concentration of point and area sources. The flow at the point sources along the river was estimated from pollution sources as shown above. Institute of Science hydrometeorology provided the concentration of pollutants from the measured data on November to December 2005. 3. Results and Discussion: 3.1 MIKE-NAM Module: Simulation of basin was done to calculate the flow at Batha, Hungthi on the upstream Day and Hoanglong River. Three hydrological stations were used such as Hungthi, Lamson and Batha. The meteorological data was used for calibration and validation of the model rainfall–runoff. Time step of data flow in this position was at the same period time of rainfall data. These measurements at hydrological stations were used in calibration and validation rainfall-runoff model for two catchments are listed in Table 1 and the weight of the rain station was calculated by the method of Thiessen polygons (Casaer et al., 1999). The rainfall, evaporation and stream flow data were used to calibrate and validate model with the rainy days from 1/1/1972 to 31/12/1973 and the rainy days from 1/1/1977 to 31/12/1977. The output of model was a process flow at the outlet section of the basin. The process flow was compared with actual measurement process to determine the suitability of the model parameters used in the basin. These results are shown clearly in the calibration model. The values of parameters in rainfall runoff model (NAM) after adjustment were recorded in Tables 2. The difference between the average simulated and observed runoff was tested by Nash-Sutcliffe criterion (Nash and Sutcliffe, 1970). Comparison between simulated and observed flow hydrograph at Batha and Hungthi stations is presented in Table 3 and in the Fig. 5 to Fig. 6. As we can see in these figures, there is a good agreement between simulated and observed flow data. The results of calibration and validation NAM model for two Batha and Hungthi catchment-areas are shown in the Fig. 7 and Fig. 8. Output of rainfall-runoff model (NAM) will be used as input boundary condition for HD and WQ modules. It will be described in the subsequent section. 3.2 Hydrodynamic Module: In the basin, there were totally 107 cross-sections in three rivers, in which: Day, Nhue and Hoanglong River. Hydrological data was used as the boundary conditions for calibration and validation model. The hydraulic

International Journal of Earth Sciences and Engineering ISSN 0974-5904, Vol. 06, No. 05(01), October 2013, pp. 1111-1119

Q. T. DOAN, Y. C. CHEN AND P. K. MISHRA

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network is shown in Fig. 9. Results of calibration model are shown that simulate flow process at Phuly, Hadong, and Giankhau quite suitable with observed data (Fig.10). The Nash-Sutcliffe efficiencies value were found be to 82% at Phuly station and 98% at Hungthi station. 3.3 Water Quality Module: There were totally 75 cross-sections on Nhue River from Phuc La to Phu Ly and on the Day River from Ba Tha to Phu Ly. Using hydraulic parameters were adjusted in the hydraulic model. The new network system is shown in Fig. 11. Calculated level for water quality is fourth level included Coli form and Phosphorus. Therefore, there are totally four parameters in model result included BOD5, DO, temperature and Coli form. Calibration model used measured data from November to December 2005. Hence, trial and error method are used to detect the appropriate parameters for the model. There are two stations using to calibrate at Thanhliet dam in the Nhue River and Tetieu channel in the Day River. There are totally 56 adjustment parameters are used when calculating the water quality fourth level. These results of model parameters calibration process are shown in Fig. 12 to Fig. 19. These results of figures above have a relative agreement between the observed and calculated values in calibration process. However, there has still a bit differences. Outputs of the model are the discharge process and concentration distribution of pollutants along the cross-section location on the River network. The model simulated with lots water quality parameters with relatively good accuracy. In the simulation process, there were still some errors in measurement and calculation with several reasons following: (I) conditions of input data were not standardized. In fact, in order to have criterion input for a model needed conduct observatory, measurement hydrologic, hydraulic, and water quality at the same time for the entire system. The data in the study was the discrete data from multiple sources so compatible ability only to a certain extent. Hence, there was the error as above; (ii) when calculation the discharge of pollution sources has some errors due to limited statistics. 3.4 Management Scenarios: Scenario 1 (S1): water discharge from upstream of the river transform from 5 m3/s to design maximum discharge through the culvert Lienmac is 36 m3/s, wastewater discharge through the Thanhliet dam varies from 1 to 5 m3/s. Calculating with BOD5 and NH4+ concentrations of pollutants is the same as in the assumption that wastewater without treatment;

Scenario 2 (S2): water discharge from upstream of the river transform from 5 m3/s to design maximum discharge through the culvert Lien Mac is 36 m3/s, wastewater discharge through the Thanhliet dam varies from 1 to 5 m3/s. BOD5 and NH4+ concentrations of pollutants is the same as in the assumption that wastewater treated following TCVN-5945-2005-B standard; These results of two scenarios are shown in Fig. 20 to Fig. 23. The purpose of building lookup table and concentration chart can help user and manager finding the BOD5 concentration when knowing Qriver from upstream and Qdischarge through Thanhliet dam. It will very useful for the manager in adjustment water flow from upstream and discharge flow through the dam in order to control the water quality in the Nhue River lying permissible limit. The BOD5 concentration at Thanhliet dam position with two scenarios have a trend decreasing when water flow from upstream increasing. The BOD5 concentration values are higher than criteria permission with two scenarios. The BOD5 concentration values at scenario 2 have suddenly decrease when Qriver transform from 30 to 36 m3/s. The BOD5 concentration values at Cuda have also a trend decrease. The BOD5 values at Cuda with scenario 1 have a trend increasing when Qriver transform 10 to 20 (m3/s) and Qdischarge transform one to two m3/s. It is can be seen that Qdischarge through the dam is a great influence to the change pollutants concentration in downstream. The BOD5 values are higher than criteria when Qriver transform 30 to 36m3/s. The BOD5 concentration values are decrease longitudinal in the river section from Thanh Lied to Cuda with two scenarios (Fig. 24). The loads of BOD5 permission have a trend increase when Qriver increasing longitudinal river section from Thanhliet to Cuda (Fig.25). The results of calculation of each scenario shown that the scenario 2 with the discharge source at Thanhliet dam has treated reaching TCVN 5945-2005-B before discharging into Nhue River water sources. The results of scenario 2 is better than the scenario 1 when has not treated with purpose reducing impact to environment. This scenario requires the wastewater from pollution sources to invest in new wastewater treatment technology and operation of treatment systems. While wastewater treatment investment have not been up to scratch as scenario 2, in order to limit pollution levels of river water need reduce pollution by controlling flow and time of wastewater discharge under the regime flow of the river. The most unfavorable conditions for self-cleaning ability of the river are a small the flow velocity and the exhaust flow source is a large. Thus, the dilution and self-cleaning ability have a great influence to water quality in the river and it is a factor of concern exploited to reduce pollution. Base on the reviews results can propose some


Numerical Modeling in Water Quality Management for Rivers – Case Study of the Day/ Nhue River Sub-basin, Vietnam solutions to reduce pollution from the lookup table and graph as follows: (I) building wastewater discharge process (Q ~ t) should be based on the flow changes rule of the river that receiving wastewater, the principle of “maximum reduction of pollutants in the river in all the period of discharge cycle”, maximizing dilution and self-cleaning ability of the river that receive wastewater; (ii) carefully investigate the water using at upstream discharge points and continuous monitoring parameters of river water pollution during the period to calculate the exhaust flow is appropriate;(iii) concentrated wastewater discharge when the water flow is maximum and limitation discharge when the flow is small. 4.

Conclusions:

This paper focused on reviewing the main pollution sources in the basin and suggested a scientific basis for waste receiving capacity assessment of stream, thereby contributing to support for the working and management wastewater discharge into water source. In all river branches, based on the results of calculation MIKE 11 model, the pollution levels on Nhue River are highest, especially from Hadong Bridge down and the location from Thanhliet dam to Cuda is the most polluted. On Day River water quality is still good but starting with phenomenon of integrated pollution in the entry with Nhue River in Phuly. According to the result of calculation with two scenarios can be seen that the water quality on Nhue River has a trend decreasing especially BOD5 parameter. The water quality on river section from Thanhliet to Cuda is seriously polluted. Base on the building lookup table and BOD5 concentration chart, the user can be easy finding the BOD5 concentration values when knowing Qriver from upstream and Qdischarge through the dam. On the other hand, the user can also adjust the flow from upstream and discharge flow through the dam in order to ensure concentration of pollutants in the river under permission standard. The building lookup table and chart help for the manager and user in adjustment wastewater discharge into river sources. Base on the result of calculation pollutants concentration longitudinal on the river support for the manager in giving waste discharge permit of waste sources into the river. 5.

Acknowledgements:

The authors would like to thank the HMEC, IMER and EA for giving opportunity and facilities to carry out this study. Also, the first author would like to give special thanks to Da-Yeh University with financial support. 6.

References:

[1] ICEM, “Improving Water Quality in the Day/Nhue River Basin: Capable Building and Pollution Sources Inventory”. Ministry of Natural Resources

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and Environment Ministry of Agriculture and Rural Development and Ministry of Construction., 2007. [2] Japan International Co-operation Agency and Ministry of Agriculture and Rural Development, The study on artisan craft development plan for rural industrialization in the Socialist Republic of Vietnam, International Development Center of Japan., 2004. [3] KEPB, “Water quality protection and monitoring of the Love River in Taiwan”. 2009. [4] Y.C. Huang, C.P. Yang, P.K. Tang, and Y.J. Lin, “A Study on Water Quality Survey and Simulation for the Love River in Kaohsiung”. Proc. 4th NPUST-USTB Symp., B34-B38pp., 2009. [5] EPA, “Volunteer stream monitoring: A methods manual”. Environmental Protection Agency, 1997. [6] P.R. Busteed, D.E. Storm, M.J. White, and S.H. Stoodley, “Using SWAT to target critical source sediment and phosphorus areas in the Wister Lake Basin, USA”. Am. J. Environ. Sci., 5: 156-163. DOI: 10.3844/ajessp.2009.156.163pp., 2009. [7] O.V. Carpio, and B.D. Fath, “Assessing the environmental impacts of urban growth using land use/land cover, water quality and health indicator: A case study of Arequipa, Peru”. Am. J. Environ. Sci., 7: 90-101. DOI: 10.3844/ajessp.2011.90.101., 2011. [8] GSMM, “Atlanta Regional Commission (ARC) Georgia”. Department of Natural Resources Environmental Protection Division, Atlanta, Georgia, USA, 2003. [9] DHI MIKE 11,“A modeling system for Rivers and Channels”. User Guide, 2007a. [10] DHI Ecolab, “WQ templates, Scientific Description”., 2007b. [11] DHI, Ecolab, “User Guide”, 2007c. [12] Vietnam Quality Regulation-Ministry of Natural Resource Environment, “TCVN 5945-2005 on Industrial waste water – Discharge standard”, 14pp. 2006. [13] M. Abbott and J. Refsgaard, “Distributed Hydrological Modeling”. Kluwer Academic Publisers., 1996. [14] J.C. Refsgaard and J. Knudsen, “Operational validation and inter comparison of different types of hydrological models”, Water Resources Research, 32(7): 2189-2202pp., 1996. [15] M.M. Shooshtari, “Principles of flow in open channels”, Shahid Chamran University Press, 15(2), 643-745pp., 2008. [16] M.B. Abbott and F. Ionescu, “On the numerical computation of nearly-horizontal flows”, Journal of Hydraulic Research, 5, 97-117pp., 1967. [17] R.K. Price, “Volume-conservative nonlinear flood routing”, Journal of Hydraulic Engineering, 135(10), 838-845pp., 2009.


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[18] J. Casaer, M. Hermy, P. Coppin, R. Verhagen, “Analyzing space use patterns by Thiessen polygon and triangulated irregular network interpolation: a non-parametric method for processing telemetric animal fixes”. International Journal of Geographical Information Science 13(5):499511pp., 1999. [19] J. E. Nash, and J.V. Sutcliffe, “River, Journal of Hydrology, 10 (3), 282–290pp., 1970.

Fig3: Structure of the NAM Model

Fig1: The flowchart of the research procedures

Figure 4: Centered 6-point Abbott scheme

Fig2: The study location area

Fig5: A comparison between calculated and observed flow at Hungthi station in calibration model


Numerical Modeling in Water Quality Management for Rivers – Case Study of the Day/ Nhue River Sub-basin, Vietnam

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Lien Mac

Ha Dong

Nhue

Ba Tha

r Rive

D ay R

er iv

D ay

Phu Ly

r Rive

Hoan g Lo Rive ng r

Hung Thi

Fig6: A comparison between calculated and observed flow hydrograph at Batha station in calibration model

Ninh Binh

Gian Khau

Fig9: Hydraulic Network in Day/Nhue River

Fig10: A Comparison between simulated and observed values of water level at Hadong, Phuly and Giankhau stations Fig7: A comparison between calculated and observed flow hydrograph at Hungthi station in validation model Phuc La

Thanh Liet

Nh ue

Ba Tha

ver Ri Te Tieu

D ay R er iv Phu Ly

Fig8: A comparison between calculated and observed flow hydrograph at Batha station in validation model

Fig11: The Water quality Calculation Network in Day/Nhue River



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1.4

Observed

1.21

Calculated

1.2 0.94

0.86

T (0C)

DO (mg/l)

1 0.8 0.53

0.6 0.4 0.2 0

Nov-05

Dec-05

45 40 35 30 25 20 15 10 5 0

40

24.1

40

24.17

23.5

Obs erved Calculated TCVN 5945-2005-B

Nov-05

2

1.87

Observed Calculated

1.2

T (0C)

DO (mg/l)

1.6

0.86 0.7

0.8 0.4 0 Nov-05

Dec-05

96

Obs erved Calculated

80

TCVN 5945-2005-B

60

50

50

Nov-05

Dec-05

40

Coliform (mg/l)

BOD5 (mg/l)

100

134

132.4 95.01

20 0

Fig14: The result of calibration BOD5 parameters at Thanhliet dam

24.27

23.6

23.6


Dec-05

18000 16000 14000 12000 10000

Obs erved

15802

Calculated

13000

TCVN 5945-2005-B

10666 8800

8000 6000 4000 2000 0

5000

5000

Dec-05

Fig18: The result of calibration Coli form parameters at Thanhliet dam 6000

50 33.49

50

35

30


20

14.23

16

5000

Coliform (mg/l)

50

BOD5 (mg/l)

24.2

40

Nov-05

60

40

40

Fig17: The result of calibration Temperature parameters at Tetieu Channel

160 120

45 40 35 30 25 20 15 10 5 0

Nov-05

Fig13: The result of calibration DO parameters at Tetieu channel

140

Dec-05

Fig16: The result of calibration Temperature parameters at Thanhliet dam

Fig12: The result of calibration DO parameters at Thanhliet dam

2

23.5

Obs erved

3000

TCVN 5945-2005-B

0

0

Fig15: The result of calibration BOD5 parameters at Tetieu Channel

Calculated

2000 1000

Dec-05

5000

4000

10

Nov-05

5000

150.6

104.8

Nov-05

204.1

280

Dec-05

Fig19: The result of calibration Coli form parameters at Tetieu Channel


Numerical Modeling in Water Quality Management for Rivers – Case Study of the Day/ Nhue River Sub-basin, Vietnam

140

80 70 60 50 40 30 20 10 0

100

BOD5 (mg/l)

BOD5 (mg/l)

120

80 Q d ischarg e 1 m3 /s

60

Q d ischarg e 2 m3 /s Q d ischarg e 3 m3 /s Q d ischarg e 4 m3 /s Q d ischarg e 5 m3 /s

40 20

TCVN 59 4 5-2 0 0 5-B

0 5

10

15

20

25

30

36

Q discharge 1 m3/s Q discharge 2 m3/s Q discharge 3 m3/s Q discharge 4 m3/s Q discharge 5 m3/s TCVN 5945-2005-B

5

Q river (m3/s)

Concentration of BOD5 (mg/l)

80

BOD5 (mg/l)

70 60 50 Q d ischarg e 1 m3 /s Q d ischarg e 2 m3 /s

30

Q d ischarg e 3 m3 /s

20

Q d ischarg e 4 m3 /s Q d ischarg e 5 m3 /s TCVN 59 4 5-2 0 0 5-B

0 5

10

15

20

15

20

25

30

36

Fig23: The value of BOD5 concentrations corresponding to river water flow and wastewater discharge at Cuda (S2)

90

10

10

Q river (m3/s)

Fig20: The value of BOD5 concentrations corresponding to river water flow and wastewater discharge at Thanhliet dam (S1)

40

1118

25

30

36

100 90 80 70 60 50 40 30 20 10 0

Co ncentratio n o f BOD5-S1 Co ncentratio n o f BOD5-S2

19,900

Q river (m3/s)

21,600

24,800

28,600

Cross-section

Fig21: The value of BOD5 concentrations corresponding to river water flow and wastewater discharge at Cuda (S1)

Fig24: The concentration of BOD5 in the longitudinal river section from Thanhliet dam to Cuda

100 90 80 70 60 50 40 30 20 10 0

18

Load of BOD5 (kg/day)

BOD5 (mg/l)

21

Q discharge 1 m3/s Q discharge 2 m3/s Q discharge 3 m3/s

15 12 9 Load of BOD5-S1

6

Load of BOD5-S2 Load of [BOD5]-TCVN

3

Q discharge 4 m3/s Q discharge 5 m3/s

0

TCVN 5945-2005-B

5

10

15

20

25

30

19,900

36

Q river (m3/s)

Fig22: The value of BOD5 concentrations corresponding to river water flow and wastewater discharge at Thanhtiet dam (S2)

21,600

24,800

28,600

Cross-section

Fig25: The variation of BOD5 load in the longitudinal river section from Thanh Liet dam to Cu Da



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Table1: Meteorology stations used to calculate in network Day, Hoanglong River Catchment

Hydrological Station

Area (km2)

Meteorology Station

Rainfall gauging Point

Upstream Hoanglong River

Hungthi

64

Nhoquan, Hoabinh

Hungthi, Lamson, Batha

Upstream Day River

Batha

1416

Nhoquan, Hoabinh

Hungthi, Lamson, Batha

Table2: The value parameters of rainfall – runoff model (NAM) for the river catchment-area Surface-Rootzone Parameters Catchment

Umax

Lmax

CQOF

CKIF

CK1,2

TOF

TIF

Batha

18.2

196

0.43

252

94.7

0.17

0.45

Hungthi

14.9

283

0.96

344

24.9

0.22

0.1

Ground Water Parameters Catchment

TG

CKBF

Batha

0.914

1217

Hungthi

0.99

3199 Initial Conditions

Catchment Name

U

L

QOF

QIF

BF

Batha

0.65

0.6

0

0

0

Hungthi

0.8

0.8

0

5

25

Table3: The result of calibration and validation of the rainfall-runoff model Catchments

Stations

NASH Calibration (%)

NASH Validation (%)

Day River

Batha

89.1

88%

Hoanglong River

Hungthi

74.3

76%
