The Yuna River basin, a watershed of about 5500 km~2 in the Dominican Republic (DR), is affected by both broad floods in the valley and flash flooding in the upper mountainous reaches. A better understanding of flood behavior and an assessment of flood control options is necessary in this watershed to protect human life and property, as highlighted by the particularly active 2008 hurricane season. Distributed hydrologic models using VfloTM of both 250m and 500m cell resolution have been developed to provide flood prediction and flood control assessment in the basin. The Upper Yuna subwatershed is topographically diverse, with steep tributaries falling from 3,000m mountains into a main channel through a relatively flat valley. The Vflo software has great applicability for this watershed compared with more standard hydrologic models because it can model the challenging topography, provide flow outputs for any portion of the watershed, and handle variable-detail GIS inputs of elevation data, soil, and land-use maps. An analysis has been performed that compares influence of cell size and hydrologic detail on tributaries of varying steepness and flow output, which proves important for location selection of flood control options. A main goal of this work is to aid this flood-prone community by getting a first model running that can provide inputs to flood timing prediction, basic floodplain mapping, and flood control assessment, but that can be quickly refined as more data of greater detail becomes available.
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