burhanpur watershed - National Remote Sensing Centre
Transcription
burhanpur watershed - National Remote Sensing Centre
SIMULATION OF SURFACE RUNOFF FOR UPPER TAPI SUBCATCHMENT AREA (BURHANPUR WATERSHED) USING SWAT Vikash Shivharea, C.K. Singha, M.K. Goelb a b Dept. of Natural Resource, TERI University, Vasant Kunj, New Delhi, India [email protected] Division of Water Resource, National Institute of Hydrology, Roorkee, India – [email protected] INTRODUCTION Water is a transparent fluid which forms the streams, lake, ocean, rain, and is one of the major constituents of the fluids of living beings. Watershed is a hydrologic unit or an area of land from which water drains, running downhill, to a shared destination or which produce water as the end product by interaction of precipitation and the land surface. Surface runoff is a term used to describe when soil is infiltrated to full capacity and excess water, from rain, snowmelt, or other sources flow over the land. The amount of water that falls as a rain within a catchment area will either flow as a surface runoff in the river which drains the basin or sinks into the ground to become ground water. GIS is an effective tool in watershed modeling as remote sensing derived information can be well integrated with the conventional database for estimating runoff which can help in planning suitable soil and water conservation measures. The SWAT works in conjuction with ArcGIS. The current study was undertaken on the application of the SWAT model which integrates the GIS information with attribute database to estimate the runoff SWAT MODEL SWAT is the acronym soil and water assessment tool. SWAT is physically, continuous time scale, river basin or watershed scale model developed by Dr. Jeff Arnold and jointly developed by the United States Department of Agriculture-Agriculture Research Services (USDA-ARS) and Agriculture Experiment Station in Temple, Texas. The model was developed to predict the impact of land management practices on water, sediment and agricultural chemical yields in large complex watershed with varying soil, land use and management condition over a long period of time. Simulation of Hydrology of a watershed is divided into two groups: - Land phase of the hydrological cycle - The water, or routing phase of the hydrological cycle Cont… water balance is the driving force behind everything that happens in the watershed to accurately predict the hydrological cycle sediment or nutrient movement. The computational components of SWAT can be grouped into different division hydrology, weather, sedimentation, soil temperature, crop growth, nutrients, pesticides and agricultural management. The hydrological cycle as simulated by SWAT is based on water balance equation: SWt SW0 Rday Qsurf Ea Wseep Qgw t where, SWt SWo T Rday Qsurf Ea Wseep Qgw i 1 : The final soil water content, : The initial soil water content, : Time in days, : The amount of precipitation on day i, : The amount of surface runoff on day i, : The amount of evapo-transpiration on day i, : The amount of percolation and bypass exiting the soil profile bottom on day i , : The amount of return flow on day I SWAT model uses hourly and daily time step data to calculate surface runoff. The Green & Ampt. Method is used for hourly data and an SCS curve number is used for daily computation. In SWAT model, a basin is delineated into various sub basin which are further subdivided into HRUs which stands for hydrologic response unit. HRUs divide the sub basin into the area of similar land use, soil type and slope. Objectives This model is applied to conduct the study for estimation of runoff in the Burhanpur Watershed. The aims and objectives of the present study for the Burhanpur Watershed are: Delineate the watershed, flow direction, flow accumulation, and stream network for the upper Tapi sub catchment area. Integrate the land use, soil map, slope, climatic data and create the HRUs for each sub basin of the study area. Carry out the hydrological modeling and estimate the surface runoff for the Burhanpur Watershed at the basin outlet. Study Area The study area is sub-catchment of upper Tapi river basin, namely Burhanpur watershed. It starts from Multai town in Betul district up to Burhanpur district. It is situated in the southern border of Madhya Pradesh near the bank of Tapi river. Extent 21˚ 22’ to 21˚ 44’ North latitude 76˚ 6’ to 78˚ 14’ East longitude Total geographic area- 9364 sq.km. Annual avg. rainfall- 830mm. The length of Tapi River which flows in Burhanpur watershed from its source to point-282 km. outlet Figure . SRTM DEM of Tapi Basin Up to Ukai dam Figure. Location of study area with respect to Tapi basin METHODOLOGY The flow chart of methodology for the rainfall runoff modeling at the basin outlet using SWAT Model set up The model was set up for the estimation of runoff. The main procedure and various step followed in model application are explained below: SWAT Project set up Automatic watershed delineation HRU Analysis Write input tables Edit SWAT inputs SWAT simulation Model setup HRUs Analysis Automatic Watershed delineation HRUs Analysis Figure. Soil Map of Tapi basin Figure. Slope map of Burhanpur Watershed Write input tables: The model requires daily data of precipitation and min. max.temprature.11 rain gauge station used in the catchment area Namely Multai, Betul, Atner, Chicholi, Bhaindeshi, Chikhalda, Dharni, Akola, khandwa, Burhanpur, Jalgaon. The climatic data for the study periods were prepared in .dbf format and than imported in the model. Edit SWAT Inputs: This menu allows the user to edit the database file in the model. It is used to setup a few additional inputs for running the SWAT model. The charecterstics of soil data and the properties of the landuse were defined in the model as per indian condition. The files were successfully rewritten and stored in personal Geodatabase of the model. After this step, the model was ready to be run. SWAT Simulation: SWAT Simulation has been done for the duration from January 01, 1992 to December 31, 1997. The SWAT model was run for the current study and output was generated at monthly time step. Results Burhanpur (1992-93) Burhanpur (1993-94) Results Burhanpur (1994-95) Burhanpur (1995-96) Conclusion The simulated flow at the basin outlet have been compared with the observed flows for four years of record (1992-93 to 1995-96) and the results are encouraging. The coefficient of determination for the monthly runoff was obtained as 0.82, 0.68, 0.92, 0.69 can be considered as a satisfactory value. SWAT model is an exhaustive model with extensive data requirement. Some of the data were available for the study basin while some other data requirements have been met from various sources. There are some limitation of the present study… The land use map obtained from the GLCF. Now-a-days, NRSC provides land use maps at finer resolution. the soil map is available four basic types. Since NBSSLUP provides more detailed soil maps for the country.