21-Application of Shallow Water Equations Models for Water Hazards Problem.

Abstract

The Shallow Water Equations (SWEs) are applicable to vast range of practical problems where water flows dominantly in the horizontal directions. The finite volume method is effective for numerically solving the SWEs in complex topography. A numerical model using a Total Variation Diminishing (TVD) finite volume scheme is developed for simulating two-dimensional transcritical surface flows. The model is applied to the valley bottoms of a West African inland valley. The valley bottoms are seasonal wetlands where rain-fed rice is cultivated, and there are several earthen dams across the valley bottoms to harvest surface water in rainy seasons and to recharge unconfined aquifers, where dug wells are installed to provide water for domestic purposes. Thus, simulation analysis of surface water flows in the valley bottoms during rainstorms is important to predict flooding of the rice fields and consequences of possible breaching of the earthen dams. A simple hydraulic groundwater flow model is proposed to explain hydrological processes in inland valleys. To implement computations, geographical, infrastructure!, and rural environmental data are collected from sheet maps, satellite images, and field surveys. Simulation results suggest suitable rehabilitation works to be done on the earthen dams to reduce risk of water hazards. It is concluded that numerical analysis using reliable numerical models with appropriate data acquisition procedures is the unique prediction tool for water hazards that could happen in extreme conditions.