Hydrological modeling of a typical ungauged basin of odisha

Abstract

Drainage basins in most parts of the world are either partially gauged or completely ungauged. Estimation of hydrological parameters in ungauged basins is very difficult and also time consuming. Hydrological modeling is the tool which simulates the catchment behaviour by solving the equations that govern the physical processes occurring within the catchment hydrologic models are usually used to simulate the catchment response for a given input. The hydrologic models take time series data and produce another time series as output. In the present work a typical ungauged basin of Odisha having geographical area of 141.32km2 has been selected as the study area. A small catchment has been chosen because the other catchments present around that area are similar to it or much less than that in terms of geographical extent. So the study was more focused in that aspect. Daily rainfall and discharge data were collected and time series analysis was done to check the correlation between them. Remote sensing and GIS techniques have been used as a tool to draw boundary map, drainage map, digital elevation map, flow direction map, flow accumulation map and land use/cover map of the ungauged basin, which were used as input for modeling through the conceptual SCS-CN model. Hydrological simulation model (HYSIM) is another distributed model used with catchment rainfall and potential evapotranspiration as its essential input parameters to simulate discharge. But it requires a large number of optimized parameters for simulation. ANN was also used to simulate runoff from the catchment rainfall. Simulated hydrographs were compared with the observed ones to look for a model that can be used with optimum input parameters and can provide best results. Results show that ANN model produced best result among the three used models and can be successfully used in an ungauged basin. ANN also takes very less parameter in comparison to the other two models as its input for simulation.