Modelo de intrusão salina no estuário do incomati baseado na influência geométrica e topográfica do estuário

Abstract

The present work focuses on the determination of saline intrusion in the Incomáti Estuary, and also on the determination of the flow that minimizes it, given its progression upstream from the estuary, driven by the reduction of the river flow, especially in the dry season. For this, the saline intrusion model that was applied by Cossa (2001) and Macuiane (2003) is used, with the particularity of this model, the model considering the influence of the estuary frontier. The model that underlies this determination, the classic salt diffusion and advection equation proposed by Bowden (1983) and Turrel et al. (1996) is presented here considering the topography and geometry of the estuary as important factors in the modeling of the saline intrusion process. The stage of dynamic tidal balance at the mouth of the estuary is considered. This study covers the summer and winter periods spanning twelve months from 2002 to 2004. The results point to a great vulnerability of the estuary to saline intrusion, especially when the flow rates are low. In most months, saline intrusion exceeds 20 km upstream of the river, which means that this process compromises agricultural activities and the ecological system in general. In order to mitigate this problem, it is necessary to establish a flow that guarantees the cultivated lands located 20 km upstream are not affected. The flow rate determined in this work has a value of 24 m3s-1.