Integrated spatial and temporal variability of the system water use efficiency in a lower Baro River watershed, Ethiopia

Abstract

The Baro Akobo River is representative of lower Baro watersheds with lost soils. Under eight landscapes, the geospatial and temporal variability of system water use efficiency (sWUE) were examined in a total area of 20,325 km2. This study used GIS, RS, Cropwat8.0, and EasyFit software. The anticipated irrigation requirement for the selected crop's driest five months of May, February, March, January, and April was 1, 0.9, 0.78, 0.78, and 0.34 l/s/h, respectively. The sub-catchment had maximum critical test values of σ = 12.6, μ = 11.9, and γ = 0, while Sor Metu showed the smallest value of 0.80, 1.75, and −0.03. Across the watershed, the sWUE varies with runoff, with a coefficient of variation of 71%. The overall accuracy of the land cover change was 81%, the Landsat 8 images of the soil-adjusted vegetation index showed a maximum value of 0.87 and a minimum of −1.5. The normalized vegetation index ranged from a maximum of 0.58 to a minimum of −1. By 2050, the sWUE will be 10% lower temporally, but its spatial variability will be 25% higher. Therefore, soil infiltration and water storage improve, which decreases runoff and the water lost by ET and raises sWUE. HIGHLIGHTS The study provides valuable information on possible future changes in system water use under a changing climate.; A large amount of soil is eroded from the upstream and supplied to the lower watershed of Baro, Gambella, by the Baro Akobo River.; Rainfall and temperature patterns over the watershed on hydrological variables and the change in land cover have an impact on the system for managing soil, water, and crops.;

Keywords

• spatial and temporal variability
• system water use efficiency
• watershed