(Luận văn) application of swat model to assess the impact of land use changes on stream discharge in nghing tuong watershed, thai nguyen province

THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY DINH NGOC HUAN TOPIC TITLE: “APPLICATION OF SWAT MODEL TO ASSESS THE IMPACT OF LAND-USE CHANGES ON STREAM DISCHARGE IN NGHINH TUONG WATERSHED, THAI NGUYEN PROVINCE” lu an va n BACHELOR THESIS Study Mode: Full-time Major: Bachelor of Environmental Science and Management Faculty: International Training and Development Center Batch: 2010 - 2015 Thai Nguyen, January 2015 DOCUMENTATION PAGE WITH ABSTRACT Thai Nguyen University of Agriculture and Forestry Degree Program Bachelor of Environmental Science and Management Student name Dinh Ngoc Huan Student ID DTN1054110040 Thesis Tittle Application of SWAT model to assess the impact of land-use changes on stream discharge in Nghinh Tuong watershed, Thai Nguyen Province Suppervisor (s) lu Abstract: Phan Dinh Binh, Ph.D an va The purpose of this research is to implement “Soil and Water Assessment Tool n (SWAT)” model and GIS to evaluation, assessment impact of land-use changes on stream discharge in Nghinh Tuong watershed (riverhead Cau river watershed) in Northern Viet Nam The watershed were cover by 56% forestry land, 30% agricultural land, and remain for others Stream discharge observed data 2002 2012 were used for calibration (2002 - 2007) and validation (2008 - 2012) The result shown that two coefficients (NSE and PBIAS) to evaluate model performance were 0.76 and 6.54% for calibration period and 0.87 and 4.74%, respectively Stream discharge strongly depends not only on quantity of precipitation but also on land use change Through the scenario 1, agricultural land (corn, orchard and tea) increases 9782.67 (2.45%), meanwhile forest (forest-mixed) decreases 1091.77 (2.75%) as compared to baseline scenario ii Additionally, precipitation increases 3.74% in mean wet season, but decreases 0.5% in mean dry season with respect to baseline period SWAT model was able to simulate stream discharge and sediment yield for Nghinh Tuong watershed successfully not only for Baseline scenario but also for Scenario In brief, SWAT proves its ability in simulation stream discharge and sediment yield in watershed level It is a useful tool to assist water quantity and quality management process in Nghinh Tuong watershed Keywords: Key words: stream discharge, watershed, GIS, SWAT model, scenario 50 Date of Submision : January 15, 2015 lu Number of pages: an va n iii ACKNOWLEDGEMENT First and foremost, I wish to express my sincere thanks to the boards of Thai Nguyen University of Agriculture and Forestry, Dean of Faculty Natural Resources Management, Department of Remote sensing and Surveying of Thai Nguyen University of Agriculture and Forestry for providing me all the necessary facilities and all the teachers who built me the scientific knowledge to complete this research In particular, I would like to thank my principal research adviser Dr Phan Dinh Binh who guided me wholeheartedly when I implement this research project I place on record, my sincere gratitude to all staffs, government and lu an people in Nghinh Tuong commune Vo Nhai district and Van Lang commune va Dong Hy district, Thai Nguyen province for their expert, valuable guidance n and generous support to our project Finally yet importantly, I take this opportunity to express our deepest appreciation to our families, relatives, friends and fellow students in class of K42-Advanced Education Program who encouraged and supported me unceasingly and all who, directly or indirectly, have lent their helping hand in this venture Thank you very much! Thai Nguyen, January 15, 2015 Student Dinh Ngoc Huan iv TABLE OF CONTENTS ACKNOWLEDGEMENT iv TABLE OF CONTENTS v LIST OF TABLES viii LIST OF FIGURES ix LIST OF ABBREVIATIONS xi Part 1: INTRODUCTION 1.1 Research rationale 1.2 Research’s objectives 1.3 Research questions and hypotheses lu an 1.4 Limitations va 1.5 Definitions n Part 2: LITERATURE REVIEW 2.1 Research situation 2.2 Soil and Water Assessment Tool (SWAT) Model 2.2.1 Concept of SWAT 2.3 SWAT Theory 2.3.1 SWAT hydrologic component 2.3.2 The land phase of the hydrologic cycle 2.3.2.1 Climate 2.3.2.2 Hydrology 2.3.3 Routing phase of the hydrologic cycle 10 2.3.3.1 Routing in river 10 v 2.3.3.2 Routing through reservoirs 10 2.3.3.3 Sediment routing 10 2.4 Component processes in model (Neitsch et al., 2005a) 11 2.4.1 Surface runoff 11 2.4.2 Underground Flow 13 2.4.2.1 Lateral subsurface flow 13 2.4.2.2 Underground flow 13 2.5 SWAT sediment component (Neitsch et al., 2005a) 14 2.5.1 The Modified Universal Soil Loss Equation (MUSLE) 14 Part 3: METHODS 16 3.1 Materials 16 lu an 3.1.1 Description and topography 16 va 3.1.2 Climatic characteristics 18 n 3.2 Methods 19 3.2.1 Watershed delineation 19 3.2.2 Soil classification and soil physical characteristics 19 3.2.3 Land cover classification 20 3.3 SWAT model 20 3.4 SWAT model performance evaluation 22 Part 4: RESULTS 25 4.1 Overview of Nghinh Tuong basin 25 4.2 Preparation input data 26 4.2.1 Climatic parameters 26 4.2.1.1 Precipitation 29 vi 4.2.1.2 Stream discharge 31 4.2.2 Spatial databases 33 4.3 Land use scenarios 36 4.3.1 Baseline scenario (2012) 36 4.3.2 Scenario (2020) 37 4.3.3 Scenario (2030) 37 4.4 Assessing the impact of land-use changes on stream discharge in Nghinh Tuong watershed, Thai Nguyen Province 41 4.4.1 Baseline scenario 41 4.4.2 Land use scenario (2020) 45 4.4.3 Land use scenario (2030) 47 lu an Part 5: CONCLUSIONS AND DISCUSSION 49 va 5.1 Conclusions 49 n 5.2 Discussion 50 REFERENCES 52 vii LIST OF TABLES Table 4.1 Summarized climatic characteristics (1983- 2012) of Nghinh Tuong watershed for SWAT simulation 27 Table 4.2 Total monthly precipitation in Nghinh Tuong watershed from 1983 to 2012.(mm) 30 Table 4.3 Observed monthly stream discharge at Nghinh Tuong outlet from 2002 - 2012 (m3/s) 32 Table 4.4 Sub-watershed characteristics of Nghinh Tuong watershed 35 Table 4.5 Sub-outlet’s characteristics of Nghinh Tuong watershed 36 Table 4.6 Land use scenarios for Nghinh Tuong watershed 39 lu an Table 4.7 Observed and simulated stream discharge for each period in Nghinh va Tuong watershed 42 n Table 4.8 Coefficients of monthly NSE and PBIAS as calibrating and validating stream discharge 44 Table 4.9 Stream discharge of Scenarios (2020) and Baseline scenario in Nghinh Tuong watershed (m3/s) 46 Table 4.10 Stream discharge of Scenarios (2030) and Baseline scenario in Nghinh Tuong watershed (m3/s) 47 viii LIST OF FIGURES Figure 3.1: Map of Vo Nhai District 18 Figure 3.2 SWAT soil database builder schematization 20 Figure 3.3 Application of SWAT on Nghinh Tuong watershed for simulation stream discharge and sediment load 22 Figure 4.1: The position of Nghinh Tuong basin 25 Figure 4.2 Monthly maximum, minimum and average temperature in Nghinh Tuong watershed from 1983 to 2012 28 Figure 4.3 Monthly relative humidity in Nghinh Tuong watershed from 1983 to 2012 28 lu an Figure 4.4 Monthly wind speed in Nghinh Tuong watershed from 1983 to 2012 29 va Figure 4.5 Total monthly precipitation in Nghinh Tuong watershed from 1983 n to 2012 31 Figure 4.6 Observed monthly stream discharge at Nghinh Tuong outlet from 2002 - 2012 32 Figure 4.7 Digital elevation model (DEM) and stream network of Nghinh Tuong watershed 33 Figure 4.8 Map of land use status Nghinh Tuong River basin in 2012 34 Figure 4.9 Soil map of Nghinh Tuong River basin in 2012 34 Figure 4.10 Sub-watershed and stream network of Nghinh Tuong watershed 35 Figure 4.11 Map of Baseline Land use scenario (2012) for Nghinh Tuong watershed 40 Figure 4.12 Map of Land use scenario 1(2020) for Nghinh Tuong watershed 40 ix Figure 4.13 Map of Land use scenario (2030) for Nghinh Tuong watershed 41 Figure 4.14 Observed versus simulated monthly stream discharge and precipitation of Nghinh Tuong watershed during calibration and validation periods 43 Figure 4.15 Observed versus simulated average monthly stream discharge during calibration and validation periods of Nghinh Tuong watershed 44 Figure 4.16 Locations of land use change for scenario (2020) for Nghinh Tuong watershed 45 Figure 4.17 Locations of land use change for scenario (2030) for Nghinh Tuong watershed 47 lu an va n x Figure 4.11 Map of Baseline Land use scenario (2012) for Nghinh Tuong lu an watershed va n Figure 4.12 Map of Land use scenario 1(2020) for Nghinh Tuong watershed 40 lu an va n Figure 4.13 Map of Land use scenario (2030) for Nghinh Tuong watershed 4.4 Assessing the impact of land-use changes on stream discharge in Nghinh Tuong watershed, Thai Nguyen Province 4.4.1 Baseline scenario The daily observed and simulated stream discharge were calculated and summarized into mean wet season, mean dry season, and mean annual Results from Table (4.7) indicate that the simulated data is lower than observed data for both mean wet and dry season for calibration (2002-2012) For example, mean wet and dry season of observed data were 24.85 and 5.13 (m3/s), while for simulated data were 14.42 and 24.15 (m3/s), respectively 41 Table 4.7 Observed and simulated stream discharge for each period in Nghinh Tuong watershed Calibration Validation Entire Period (2002-2007) (2008-2012) (2002-2012) Items Observed (m3/s) Mean annual Mean wet season Mean dry season 15 10.90 12.95 24.85 18.55 21.70 5.13 3.35 4.23 Simulated (m3/s) 14.42 10.71 12.55 Mean wet season 24.15 18.35 21.24 4.65 3.10 3.90 lu Mean annual an Mean dry season va n 42 lu an va n Figure 4.14 Observed versus simulated monthly stream discharge and precipitation of Nghinh Tuong watershed during calibration and validation periods 43 Table 4.8 Coefficients of monthly NSE and PBIAS as calibrating and validating stream discharge Simulation period Period Monthly NSE PBIAS (%) Calibration 2002 - 2007 0.76 6.54 Validation 2007 - 2012 0.87 4.74 Table 4.8 shows the results of the evaluation model through the NSE index PBIAS index quite good + Commissioning phase (2002-2007) NSE index = 0.76; PBIAS = 6.54 + Testing phase (2008-2012) NSE index = 0.87; PBIAS = 4.74 lu an va n Figure 4.15 Observed versus simulated average monthly stream discharge during calibration and validation periods of Nghinh Tuong watershed 44 Figure 4.15 illustrates that SWAT tends to underestimate stream discharge for major months of year The conceivable reason contributing to this result is the land use map generated based on year 2010 survey data which may cause differences in land use installed in the previous period Another reason causing discrepancy between simulated and observed sediment yield may be attributed to soil types 4.4.2 Land use scenario (2020) Stream discharge of Scenario results at Nghinh Tuong outlet were summarized in Tables 4.9, and Figure 4.16 lu an va n Figure 4.16 Locations of land use change for scenario (2020) for Nghinh Tuong watershed 45 Table 4.9 Stream discharge of Scenarios (2020) and Baseline scenario in Nghinh Tuong watershed (m3/s) Stream discharge (m3/s) Precipitation (mm) Items Mean annual Baseline Scenario Baseline Scenario Difference Change Scenario Scenario (%) 1698.0 1753.12 14.42 14.93 0.50 3.46 1390.2 1453.78 24.15 25.20 1.05 4.35 305.8 297.34 4.65 4.60 -0.05 -1.09 Mean wet season Mean dry season lu an In general, stream discharge strongly depends not only on quantity of va precipitation but also on land use change; high precipitation will lead to high n stream discharge and land use change with increasing agricultural land will reduce stream discharge, especially in dry season In Mean wet season, precipitation increases 63.58 mm (4.57%) from 1390.20 mm in 2012 to 1453.78 mm in 2020 In this case, stream discharge in 2020 is 25.20 m3/s, increases 1.05 m3/s (4.35%) in comparison with baseline scenario period However, in Mean dry season, stream discharge in 2020 decreases 0.05 m3/s (1.09%) in comparison with baseline scenario period, from 4.65 m3/s (2010) to 4.60 m3/s (2020) Meanwhile, precipitation decreases 8.46 mm (2.77%) from 305.80 mm in 2010 to 297.34 mm in 2020 Therefore, mean annual of stream discharge just increases 3.46% (from 14.42 m3/s to 14.93m3 /s) with respect to baseline period 46 4.4.3 Land use scenario (2030) lu Figure 4.17 Locations of land use change for scenario (2030) for Nghinh an Tuong watershed va n Table 4.10 Stream discharge of Scenarios (2030) and Baseline scenario in Nghinh Tuong watershed (m3/s) Precipitation (mm) Items Mean annual Stream discharge (m3/s) Baseline Scenario Baseline Scenario Difference Change Scenario Scenario (%) 1698.0 1771.58 14.42 15.05 0.63 4.37 1390.2 1478.26 24.15 25.48 1.33 5.51 305.8 291.32 4.65 4.56 -0.09 -1.94 Mean wet season Mean dry season 47 Simulated result of Scenarios stated that stream discharge at mean wet season increases 1.33 m3/s (5.51%) from 24.15 m3/s (baseline period) to 25.48 m3/s (2030), while that at mean dry season decreases 0.09 m3/s (1.94%) from 4.65 to 4.56 m3/s (Table 4.10) One of the reasons of decreasing stream discharge in dry season is: when 1190.95 and 555.78 Forest-mixed land is converted into Agricultural land, especially Corn and Agricultural land-row crops which consume more water for cultivation Moreover, reducing forest land brings about decrease of ability for keeping and generating water within watershed lu an va n 48 PART CONCLUSIONS AND DISCUSSION 5.1 Conclusions In this research, SWAT model was setup, calibrated and validated successfully at Nghinh Tuong watershed with the drainage area of 39700.58 In order to assess the impacts of land use change on stream discharge and sediment yield in Nghinh Tuong watershed, the land use scenarios were formulated combined with climate change in SWAT simulation In scenario 1, agricultural land (corn, orchard and tea) increases 786.08 (1.98%), meanwhile forest (forest-mixed) decreases 1091.77 (2.75%) as compared to baseline scenario Additionally, precipitation increases 3.74% in mean wet season, but decreases 0.5% in mean dry season with respect to baseline period lu In scenarios 2, agricultural land increases 1348.87 (3.39%) meanwhile an forest decreases 1838.14 (21.41%) with respect to baseline scenario respectively va n Furthermore, precipitation increases 6.33% in mean wet season, but decreases 4.74% in mean dry season for scenario SWAT was able to simulate stream discharge and sediment yield for Nghinh Tuong watershed successfully not only for Baseline scenario but also for Scenario During calibration process, sensitive parameters were identified as: CN2 (curve number), ESCO (soil evaporation compensation factor), EPCO (plant uptake compensation factor), C FACTOR (cover and management factor) Simulation result for Baseline scenario showed a good agreement between observed and simulated data SWAT shows its high capability in stream discharge Through this research we have constructed Actiview database and Spatial databases for SWAT model 49 The results of running the model calculated stream discharge for the period (2002 - 2012) shows that Mean annual: 12,55 m3/s Mean wet season: 21.24 m3/s Mean dry season: 3.90 m3/s The results of the evaluation model through the NSE index PBIAS index quite good In brief, SWAT proves its ability in simulation stream discharge and sediment yield in watershed level It is a useful tool to assist water quantity and quality management process in Nghinh Tuong watershed 5.2 Discussion lu an The Application of SWAT model is very large However, the input data va requirements for models and need much time to process the data especially, n maps like topographic maps, soil maps, forest maps and their attribute data To be able to use this model to quantitatively assess the impact of the floods forest necessarily have a uniform data input So that, the following time, we need to investigate basic data such as meteorology, climate, land, soil, hydrology, forest etc to be able to put the model into more widespread use The model was validated for stream discharge and sediment yield at main outlet, but not yet validated for sub-outlets due to the limited data Hence, the validation process for stream discharge and sediment yield process at some important sub-outlets must be done in the next step to ensure the validity of simulation In Nghinh Tuong watershed, when farmers cultivate agricultural crops, (especially in slope land) and apply pesticides and fertilizers for crops, which 50 make not only soil erosion but also pesticides and phosphorous load on stream into downstream However, there were no comprehensive assessments of pesticides loads in this river basin Hence, a modeling effort to simulate these problems in Nghinh Tuong watershed should be implemented in the near future lu an va n 51 REFERENCES Arnold, J G., J R Williams, and D R Maidment 1995 Continuous-time water and sediment-routing model for large basins Journal of Hydrology Engineering, ASCE 121(2): 171-183 Arnold, J G., R S Muttiah, R Srinivasan, and P M Allen 2000 Regional estimation of base flow and groundwater recharge in the upper Mississippi basin Journal of Hydrology 227(1-4): 21-40 Arnold, J G., R Srinivasan, T S Ramanarayanan, and M Di Luzio 1999 Water resources of the Texas gulf basin Water Science and Technology 39(3): 121-133 Ella, V B 2005 Simulating soil erosion and sediment yield in small upland watersheds using the WEPP model In: I Coxhead and G.E Shively, Land use change in tropical watersheds: Evidence, causes and remedies CABI lu publishing Wallingford, Oxfordshire, UK, p109-125 an Gassman, P.W., M.R Reyes, C.H Green, and J.G Arnold The Soil and Water va n Assessment Tool: historical development, applications, and future research directions Transaction of ASABE 50(4): 1211-1250 Govender, M., and C S Everson 2005 Modelling streamflow from two small South African experimental catchments using the SWAT model Hydrology Processes 19(3): 683-692 GSOV (General Statistics Office of Viet Nam) 2008 Statistical year book 2008, National Political Publishing House, Ha Noi, Viet Nam Moriasi, D N., J G Arnold, M W Van Liew, R L Binger, R D Harmel, and T Veith 2007 Model evaluation guidelines for systematic quantification of accuracy in watershed simulations Transaction of ASABE 50(3): 885-900 Nash, J E., and J V Sutcliffe 1970 River flow forecasting through conceptual models: Part I A discussion of principles Journal of Hydrology 10(3): 282290 Neitsch, S L., J G Arnold, J R Kiniry, and J R Williams 2005a Soil and Water Assessment Tool Theoretical Documentation, Version 2005 Temple, 52 Tex.: USDA-ARS Grassland, Soil and Water Research Laboratory Available November, at: www.brc.tamus edu/swat/doc.html (Accessed on 2006) Neitsch, S L., J G Arnold, J R Kiniry, and J R Williams 2005a Soil and Water Assessment Tool Theoretical Documentation, Version 2005 Temple, Tex.: USDA-ARS Grassland, Soil and Water Research Laboratory Available November, at: www.brc.tamus edu/swat/doc.html (Accessed on 2006) Neitsch, S L., J G Arnold, J R Kiniry, R Srinivasan, and J R Williams 2005b Soil and Water Assessment Tool Input/Output File Documentation, Version 2005 Temple, Tex.: USDA-ARS Grassland, Soil and Water Research Laboratory Available at: www.brc.tamus.edu/swat/doc.html (Accessed on November 2006) NTPC (Nghinh Tường People’s Committee) 2010 Report on Land use planning lu Thai Nguyen, Viet Nam an Phan, D B., C C Wu and S C Hsieh 2011b Impact of Climate Change on va Stream Discharge and Sediment Yield in Northern Viet Nam Journal of n Water Resources 38 (6): 783-792 Population and population density in 2009 by province" General Statistics Office of Vietnam (accessed on September 2011) SWAT 2007 Soil and Water Assessment Tool: SWAT model College Station, Texas: Tex A&M University Available at: www.brc.tamus.edu/swat/soft_model.html Accessed 21 February 2007 Thai Nguyen Potal, General Introdution about Vo Nhai District, http://www.thainguyen.gov.vn/wps/portal/detailnews?WCM_GLOBAL_CO NTEXT=/web+content/sites/home/ct_gttn/ct_gt_gtc/gt.tc.vn&catId=CT_GT _GTC&comment=GT.TC.VN (accessed on15/01/2014) Ton, T C., T B Le, K Nguyen and V T Nguyen 1999 Handbook of Vietnam Soil Classification and Assessment Agricultural Publishing House Hanoi, Viet Nam 53 Van, L., M W., and J Garbrecht 2003 Hydrologic simulation of the Little Washita River experimental watershed using SWAT Journal of American Water Resources Association 39(2): 413-426 Williams, J R 1975 Sediment routing for agricultural watersheds Water Resources 11(5): 965-974 lu an va n 54