An assessment of the drainage system and waterlogging at the Silalabuhwa irrigation scheme

Abstract

This study investigates the threats posed by waterlogging and salinization to agricultural productivity at the Silalabuhwa Irrigation Scheme in Zimbabwe. To assess these threats, soil samples (n = 20) were collected from both waterlogged and non-waterlogged areas within irrigation blocks and analyzed for texture, pH, and electrical conductivity (EC). Water samples from the dam and canal were similarly analyzed for pH, turbidity, and EC. Additionally, key informant interviews provided valuable insights into the extent and causes of waterlogging, along with potential solutions. Slope analysis and mapping of waterlogged areas were conducted using topographical tools and GPS technology. The findings reveal a significant challenge, with 87.96 ha of land affected by waterlogging, which consequently reduces the available area for irrigated agriculture. Areas with non-functional drainage systems exhibited the most severe waterlogging, highlighting deteriorating infrastructure and poor water management practices as the primary culprits. To address these issues and ensure the scheme's long-term sustainability, the study proposes a multi-pronged approach including rehabilitation of irrigation infrastructure, leaching of excess salts from the soil, staff training on improved irrigation practices, and the implementation of a water-efficient irrigation system equipped with sensors to precisely control water application. By implementing these recommendations, this study aims to contribute to improved land use efficiency, enhanced crop yields at Silalabuhwa Irrigation Scheme, and ultimately, regional food security.