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BY

K.SINDHU

131864

APPLICATIONS OF ARC SWAT MODEL FOR HYDROLOGICAL

MODELLING

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• SWAT (Soil & Water Assessment Tool) is a river basin scale and continuous-time model

• Used to predict the impact of management on water, sediment, and agricultural chemical yields in large complex watersheds.

INTRODUCTION

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In SWAT, a watershed is divided into multiple subwatersheds, and the subwatersheds are divided into Hydrological Response Units (HRUs)

HRU’s are aggregated land areas with in sub basinrepresent percentages of the subwatershed areacomprise of unique land use, soil and management

conditions

4Figure 1: ARC SWAT tool in ARCMAP Environment

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The model setup involves the following five steps

Watershed delineation HRU definition Weather data definition Edit SWAT input Run SWAT

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WATERSHED DELINIATION

Figure 2: Menu for Automatic Delineation of Watershed in ArcSWAT model

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HRU ANALYSIS

Figure 3: Menu for Hydrologic Response Unit Analysis in ArcSWAT model

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IMPORT WEATHER DATA

Figure 4: Menu for Weather Data Definition in ArcSWAT model

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RUN SWAT

Figure 5: Menu for Setup and Run SWAT model simulation

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Benedini et al.,(2003) developed an inflow-outflow model for the Alban Hills using SWAT model.

For the simulation: SCS-Curve number-runoff, Hargreaves- evapotranspiration computations.

LITERATURE REVIEW

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Pierluigi et al.,(2003) presented the application of SWAT model to evaluate the water budget for several sardinian catchments and to predict future scenarios.

Parameters: land use, soil type, surface water systems, etc.

For daily weather inputs, statistical analysis of the sardinian climatic data has been carried out.

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Jain et al.,(2010) selected the swat model for the estimation of runoff and sediment yield for an intermediate watershed of Satluj river, Himachal pradesh.

Parameters: Digital elevation model, Landuse, Soil, hydro-meteorological data.

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Tesfahunegn et al.,(2012) presented the application of SWAT model to identify hotspot soil degradation sub-catchments.

Based on estimated runoff, sediment yield and nutrient losses in the Mai-Negus catchment, northern Ethiopia

parameters: digital elevation model (DEM), land use-cover, soils and daily observed weather data.

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CASE STUDY-1

Ashok et al.,(2003) analysed the potential applicability of SWAT in managing check dams constructed as on-stream reservoirs and impoundment structures.

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Study area: BANHA, Jharkhand, India.

Figure 6: BANHA WATERSHED

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Data used: Daily rainfall, runoff and sediment discharge, and maximum and minimum temperature

Figure 7: Measured Rainfall, runoff and sediment (June to October)

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o Divided into 5 sub watersheds based on the drainage and land use pattern.

o Calibrated the model for 1996 and then for nine years (1993-2001).

o Validated by comparing the measured water yield and sediment load with their measured counterparts for the year 1996.

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Figure 8: Water yield calibration

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Figure 9: Sediment yield calibration

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Figure 10: Sediment yield comparision during 1996-2001 with real situation

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Figure 11: No check dam situation, sediment transport

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CASE STUDY-2

Varanou et al.,(2003) presented a method for quantifying the impacts from specific land use changes on the runoff . The water cycle was simulated with the use of the SWAT, and the land use change scenarios were created using the Land Use Development Model (LADEMO).

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Study area: Pinios catchment in Thessaly, Greece.The result of a (LADEMO) model run is a digital map

of future land use.Land use change scenarios:

Expansion of agricultural land

Deforestation

Expansion of urban areas

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Figure 12: Digital maps of land use: (a) Original pattern of land uses, (b) after the expansion of agricultural land, (c) after the deforestation and (d) after the expansion of

urban areas.

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Table 1: Maximum and minimum values of discharge change percentages for the three implemented scenarios.

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Swat model can be effectively used for • development of inflow-outflow model, • estimating available water resources, • managing check dams, • quantifying the impacts from land use changes on the

runoff and • modelling the long term impacts of best management

practices in watershed.

SUMMARY

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Check dams contribute to enormous reduction of sediment transport from the watershed.

The simulated and observed sediment transport from the watershed compares closely and thus shows a strong applicability of the SWAT model in accounting for these processes in small watersheds.

SWAT makes an accurate estimation of the deposited sediments in check dams.

The land use change which is causing a greater modification of daily and monthly total discharge is the change introduced by the deforestation scenario.

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Ashok., 2003: Potentials and Applicability of the SWAT Model in Check Dam Management in a Small Watershed. 2nd international swat conference, 2003, 76-82

Benedini., 2003: Model SWAT Application in the Alban Hills. 2nd international swat conference, 2003, 32-37

Jain., 2010: Simulation of Runoff and Sediment Yield for a Himalayan Watershed Using SWAT Model. J. Water Resource and Protection, 2010, 2, 267-281

REFERENCES

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Pierluigi., 2003: Estimating Available Water Resources of the Sardinian Island Using the SWAT model. 2nd international swat conference, 2003, 64-70

Tesfahunegn., 2012: Application of SWAT model to assess erosion hotspot for sub-catchment management at Mai-Negus catchment in northern Ethiopia. East African Journal of Science and Technology, 2013, 2(2):97-123

Varanou., 2003: Application of the SWAT model for the Sensitivity Analysis of Runoff to Land Use Change. 2nd international swat conference, 2003, 90-93

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Thank you