Early detection of dam sedimentation and its socioeconomic impacts on the livelihoods of smallholder farmers: a case of Bontanga irrigation dam

ABSTRACT

A relationship between sediment accumulation and water depletion in the reservoir.

This study addresses reservoir sedimentation resulting from anthropogenic activities, which significantly reduces reservoir storage capacity and threatens water resources. A regression model together with published secondary data was utilized to develop predictive models to forecast the volume of sediment accumulation and the corresponding decline in reservoir storage capacity. The model accuracy was assessed using adjusted R2, coefficient of determination (R2), and mean absolute percentage error (MAPE). These statistical metrics showed strong model performance, adjusted R2 = 0.90, R2 = 0.95, MAPE = 8.53% for sediment volume accumulation, and MAPE = 0.40% for water volume declines. The analysis revealed that without prompt conservation measures in the Bontanga watershed, sediment accumulation will reach 62.86% by 2070, leading to a 30.56% reduction in the area allocated for rice cultivation. These changes are expected to cause substantial direct job losses among smallholder farmers, exacerbate household food insecurity, and increase income poverty within the farming community. The study underscores the urgent need for proactive and sustained watershed management interventions in the Bontanga catchment to mitigate sediment inflow and maintain reservoir functionality over the next 45 years.