Physically-based distributed hydrological modeling over Guadalupe River Basin




Chintalapudi, Singaiah

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The hydrological models try to simulate the watershed behaviors in terms of simulating the runoff generation, discharge, and other processes by solving the physics-based equations that govern the physical processes occurring within the watershed. At present, hydrological models are the essential tools for hydrological applications such as flood forecasting, management, and water resources management. When developing a distributed hydrological model, one has to consider the influence of spatial variability on runoff generation. This research contributed to distributed hydrological modeling of hydrologic processes over the Guadalupe River basin in three ways. The first part of the study includes an analysis of the impacts of land use/cover changes and spatial variability of rainfall on the simulated peak flows and runoff volumes. The second part of the study presents a thorough examination of the hydrologic worth of various rainfall products, including NEXRAD MPE, rain gauges, CMORPH, PERSIANN, and TRMM products and recommends the best product to be used for hydrological modeling over the Guadalupe River Basin. The last part of the study includes the development a high-resolution physically based, distributed hydrological model for the entire Guadalupe River basin. The first two studies were conducted on the upper Guadalupe River Basin above Comfort, Texas (Area = 2170 km2), and the Guadalupe River Basin below Comfort, Texas and above Canyon Lake respectively (Area = 1232 km2) respectively. The distributed hydrological model was developed over an 11,285 km 2 regional watershed. The results from the first study demonstrate that the effect of urbanization on the watershed in the past two decades did not have made any significant effects on the hydrologic response. The effect of urbanization on the hydrologic response increases as the size of the rainfall event decreases. The second study concluded that the NEXRAD MPE simulated streamflows matched the observed streamflows much better than satellite products for the July and August 2007 flood events. Among all of the satellite precipitation datasets, the TRMM 3B42 showed consistent and better performance in streamflow simulation. The PERSIANN coarse resolution product (PERSIANN 0.25 degree) yields better streamflow results than PERSIANN high resolution products (PERSIANN CCS). The infiltration capacity in the watershed decreases as the rainfall volumes increases. The third study identified the set of hydrological parameters that can be used for future hydrological studies over the entire Guadalupe Basin. The methodology can be applied over all major river basins in Texas.



Distributed modeling, GSSHA, Land use/cover changes, NEXRAD precipitation, precipitation products, satellite precipitation



Civil and Environmental Engineering