Sewage discharges and nutrient levels in Marimba River, Zimbabwe

Soil wearing away or erosion is a chief agent of land loss in agricultural land and is regarded worldwide as a serious environmental hazard. This study performed watershed prioritization using morphometric parameters based on fuzzy best worse method (F-BWM) and GIS integration for Gusru Watershed, India. This study prioritizes sub-watersheds of the study area from viewpoint of soil erosion using five major parameters i.e., stream frequency (F_s), relative relief (R_r), length of overland flow (L_o), relief ratio (R_h) and drainage density (D_d). Fuzzy based Best Worse Multi-Criteria Decision-Making (F-BWM) Method was used to assigning weights to used criteria and combining them to achieve erosion susceptibility for each sub-watershed. Results showed that sub-watersheds 9, 14, and 5 were most susceptible to soil erosion and sub-watershed 3 was the least from the viewpoint of soil erosion ranking.

Improved drought and flood management in semi-arid transboundary basins requires a better understanding of the connections between dry and wet extremes, surface water and groundwater, upstream and downstream, and local communities and formal governance actors. This study describes a multi-disciplinary and mixed-methods research in the Limpopo River Basin, southern Africa. The methodology included hydrometeorological data analysis to identify drought and flood events, group discussions with 240 local community participants about drought and flood processes, impacts and preparedness, and interviews with 36 (inter)national and regional water managers and policymakers about drought and flood governance, early warning and communication. Additionally, we co-created drought and flood management scenarios through transboundary and national workshops and modelled these with an integrated surface water-groundwater model. We found that floods are crucial for aquifer recharge, providing baseflow during droughts, but also impactful for communities, who receive less training and support for floods than for droughts. Flood early warnings (if provided) are often not acted upon because of cultural values or limited resources. Drought and flood adaptation strategies were simulated to be effective, but factors like investment and maintenance costs, technical capacity and community uptake impact implementation. Furthermore, technical measures alone are inadequate to reduce community risk if underlying vulnerabilities are not addressed. Therefore, strengthening connections between communities and formal governance actors and better transboundary management of surface water and groundwater connections could yield significant benefits. Contribution: This study provides 11 distinct recommendations for managing drought and flood risk, focussing on the four connections analysed.