Operational Evaluation of Rainfall Monitoring Networks in the Upper Benue River Basin

Adequate rainfall monitoring networks are the foundation of hydrological forecasting and water resource management systems, yet network design and maintenance represent persistent operational challenges across Nigeria's river basins. This study conducts an operational evaluation of the rainfall monitoring network in the upper Benue River Basin, covering Adamawa and Taraba states, assessing network adequacy, data continuity, and operational maintenance standards. A network adequacy assessment was performed using WMO guidelines for minimum station density in semi-arid regions, combined with spatial analysis of gauge coverage gaps using Thiessen polygon delineation in GIS. Maintenance records and data continuity reports for 2018 to 2022 were obtained from the Benue River Basin Development Authority and NiMet Yola. Findings indicate that the current network density of one gauge per 2,800 square kilometres is approximately 40 percent below the WMO recommended minimum for the region. Data continuity analysis reveals that 42 percent of operational gauges have missing records exceeding 15 percent in at least one year, with the majority of data gaps attributable to equipment damage and delayed battery replacement. The study recommends a strategic network densification plan targeting five priority sub-basins and introduces a cost-effective tipping bucket gauge maintenance protocol adaptable to field officer capacity constraints. Keywords: rainfall monitoring, network evaluation, Benue River Basin, WMO, hydrological forecasting.