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Nagraj S. Patil ¹, Vinaykumar S. Patil ¹, H. Vijaykumar ¹

Affiliations
1 Department of Water and Land Management, Visvesvaraya Technological University, Belagavi, Karnataka, IN

Abstract

The use of hydrological models to simulate rainfall-runoff events is an important tool for the evaluation of a watershed for different land uses, the SWMM being one of the most widely used models to represent these processes in urban areas, one of selected area is VTU campus, Belgaum. This work applied the SWMM in six small sub catchment basins in VTU campus, Belgaum aiming to evaluate the impact of the model parameters on the watershed responses. Observed pluviometric and fluviometric data were used in the model calibration, a process made by a manual trial and error method and the simulated and the observed runoff in the outlets were compared. In the calibration, the average determination coefficients from 0.87 to 0.99 were obtained, as were runoff peak errors from 0% to 31% and runoff volume errors from 0.3% to 71.1%. The calibrated parameters were distinct for high and low rainfall intensities in the same basin. The sensitivity of the parameters was shown to be variable according to the physical basin characteristics.

Keywords

Urban Runoff, Hydrological Modelling, Sensitivity Analysis, SWMM Model.

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Nagraj S. Patil ¹, Santosh Dhungana ¹, B. K. Purandara ²

Affiliations
1 Department of Water and Land Management, VTU, Belagavi, Karnataka, IN
2 National Institute of Hydrology, Hard Rock Regional Centre, Belagavi, Karnataka, IN

Abstract

In the present study, an attempt is made to simulate the current groundwater level in the Ghataprabha sub-basin (Krishna basin) in southern India. For this purpose, a single layered aquifer was conceptualized using Visual MODFLOW Flex ver.14.2. Model calibration was carried out using Parameter Estimation (PEST), with R², RMSE and NRMSE as model evaluation criteria. Model behaved well with the value of 0.99, 6 m and 2.13% for R², RMSE and NRMSE respectively. Groundwater modelling results showed that there is an increase of 1.46 m of groundwater level in 5 years. Incorporating the increasing trend of groundwater level in planning water resource projects would be fruitful.

Keywords

Groundwater, Ghataprabha, PEST, Visual MODFLOW FLEX.

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Nagraj S. Patil ¹, A. Thapa ², S. Dhungana ¹

Affiliations
1 Department of Water and Land Management, Visvesvaraya Technological University, Karnataka-590018, IN
2 International Centre for Integrated Mountain Development (ICIMOD), Khumaltar, Lalitpur, NP

Abstract

This study presents a comprehensive modeling environment of Soil and Water Assessment Tool (SWAT), hydrological model. Sequential Uncertainty Fitting Program (SUFI-2) in SWAT-Calibration and Uncertainty Programs (SWAT-CUP) was used for automatic calibration. To examine this framework, a study on annual water balance components including precipitation, evapotranspiration and water yield as well as simulating stream flow in the Sina Catchment was conducted. Hydrological Simulations were conducted for Base Line, A2 and B2 scenarios using PRECIS HadRM3 data. Model performance was evaluated using several statistical parameters, such as the Nash-Sutcliffe coefficient and the normalized objective function. For calibration (1981-85), R2 was obtained as 0.92 and for validation (1986-1990) it was 0.76. Similarly, NSE during calibration was 0.88 and during validation was obtained as 0.76. Calibration and validation results showed good agreement between simulated and observed data. The overall investigation carried out during this study indicates that the simulated Sina catchment is very sensitive to climatic variations. Precipitation trend is decreasing in A2 as compared to Base Line with slight overall increase whereas in B2 precipitation is increasing significantly. While only little changes can be observed in the rate of evapotranspiration, water yield is increasing drastically. The study of the discharge for a thirty year period under climate change scenarios showed that there was an increase in river discharge in future scenarios. Compared to the Base Line scenario (1961-1990), A2 and B2 scenarios (2071-2100) have much higher minimum and maximum annual discharges.

Keywords

Climate Change, Water Balance Component, SWAT Model, PRECIS, Flow Analysis, SWAT-CUP.

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