Hydrological Modeling of an Agricultural Watershed using HEC-HMS, Remote Sensing and GIS
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Date
2015
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Publisher
AAU, Anand
Abstract
Runoff estimation is very important for water resources planning and management. Hydrological modeling is inevitable for accurate and precise estimation of runoff from a watershed. A major problem in the hydrological modeling is the inadequate field measured data to describe the hydrologic processes.With unavailability or limited availability of data, the quantitative understanding and prediction of the runoff generation processes and its transmission to the watershed outlet remains one of the most challenging area of hydrology. The use of remote sensing and GIS, in combination with semi distributed hydrological model provides new possibilities for deriving spatially distributed time series of input variables, as well as new means for calibration and validation of the hydrological model. In the present study, the HEC-HMS model is applied to the Hadaf river watershed, which is predominant with agricultural land and falls under semi-arid zone, where water resources planning and management is necessary for irrigation scheduling, water harvesting, flood control, drought mitigation and design of various engineering structures. In this study four different events of meteorological & discharge data, DEM, LISS-III and LISS-IV remote sensing imagery, soil maps are applied as inputs for HEC-HMS models. The effect of different resolution of DEMs, effect of land use change, effect of different resolution of land use imagery are also evaluated to assess their effectiveness in watershed delineation & drainage network, runoff generation, prediction accuracy, respectively. Two of the important transformation methods namely SCS UH and Clark UH are evaluated for performance comparison. Two of the important optimization methods (i.e. Univariate Gradient method and Nelder Mead method) are also evaluated to assess their effectiveness for rainfall runoff modeling. Initially, geo-morphological analysis of the watershed is carried out using the capabilities of remote sensing and GIS to prioritize the watershed for soil and water conservation measures. Then, conceptual hydrological HEC-HMS model is applied to transform rainfall into runoff for two of the selected event, and thereafter, the parameters related to initial loss, unit hydrographs, reservoir and channel routing, were calibrated and validated using the another two events in the watershed. It is found in this study that instead of low resolution (i.e. 90 m) SRTM DEM found to be better than ASTER DEM. Significant change in land use is observed from year 2008 to 2012 in this study. The finer resolution remote sensing image LISS-IV produced better classification and resulted in improved accuracy of HEC-HMS modeling. It is found that the Clark method produces better results than SCS-UH transformation method in rainfall-runoff simulation in terms of both the runoff peak and runoff volume. In parameter optimization, the overall performance of Nelder Mead method is found better than Univariate Gradient method. Better performance of all these models for the new event of rainfall-runoff transformation approves the applicability of HEC-HMS model in the study area. The findings in the present study are very useful for water resources engineers, researchers and will play an important role in water resources planning and management.
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Keywords
agriculture, engineering, Modeling