Analysis of Spatial and Temporal Trend for Hydro-climatic Parameters in the Kilombero River Catchment, Tanzania

Abstract Perceived and real-life water availability have raised social and economic conflicts that necessitate proper water management. This requires an understanding of spatial-temporal trends of hydro-climatic variables as the main contributor to available water for use by sectors of economy. In this study, we have analyzed the trend of hydro-climatic variables viz. precipitation, temperature, evapotranspiration and river discharge. One downstream river gauge station was used for discharge data whereas a total of 9 daily observed and 29 grided satellite stations were used for climate data. Climate Hazards Group InfraRed Precipitation was used for precipitation data and Observational-Reanalysis Hybrid was used for Temperature data. Mann-Kendall Statistical test, Sen’s slope estimator and ArcMap Inverse Distance Weighted Interpolation functionality were employed for temporal, magnitude and spatial trend analysis respectively. Results show that on the latter, there are three main climatic zones in the study area viz. Udzungwa escarpment, Kilombero valley and Mahenge escarpment. On the former, with exception of the declining potential evapotranspiration trend, all other variables are on increase. This is with catchment rates of 2.08 mm/y, 0.05 oC/y, 0.02 oC/y, 498.6 m3/s/y and − 2.27 mm/y for precipitation, Tmax, Tmin, river discharge and PET respectively. Furthermore, there is a synonymous seasonality pattern for all variables with significant range, especially in river discharge. However, it is recommended to improve water resources management practices to limit flow impairment as expansions in sectors of economy are expected. Furthermore, landuse change analysis is recommended to ascertain actual trend and hence future water uptake.