Salinity Distribution in a Tropical River-Estuary Continuum through Numerical Modelling: Case of the Wouri-Nkam River Estuary, Cameroon

Abstract

In estuaries environments, the distribution of salinity controls the resourcing of freshwater for agriculture, aquaculture and human consumption; it also regulates the functioning of critical natural habitats. Consequently, there is a particular need for a better understanding of the salinity distribution along river estuaries continuum and for simple predictive relationships linking salinity to estuarine characters and hence environmental conditions. Despite numerous global insightful studies, there are limited studies regarding the spatial patterns of salinity distribution in African estuarine systems. The present study fills this gap using idealized 1-dimentional (1-D) modelling of the Wouri-Nkam River Estuary, Cameroon under various seasonal and tidal conditions. The model results reveal a seasonal tidal excursions varying from 21.4 km (dry season), 18.1 km (transition season), and 14.66 km (wet season). The model performs best during the wet and transition seasons. The year 2050 and 2100 predictions reveal salt intrusion distance of 21 km and 41 km, respectively, indicating that the whole estuary and its surrounding environment will be polluted by marine water in the latter year. The results of this study are important for the region's water resource managers and decision-makers in mitigating the effects of climate change and associated Sea Level Rise (2100 scenario) on the coastal ecosystems since their continuous modification will negatively impact the living standard of Cameroon’s growing population, and the sub region at large.