Abstract

The Iishana is a shallow, low-slope channel system located in the Cuvelai basin (Southern Angola and Northern Namibia), characterised by drought and flood cycles due to erratic climate variability. The knowledge gap regarding the actual water needs in the area, the number of residents within the system, the seasonal influence of cattle migration, and poor socio-economic conditions, make the population even more vulnerable to droughts. The main objective of this study is to estimate the water demand by the rural population on the Angolan side of the Iishana system, attempting to fill the knowledge gap. To reach the demand estimates, a mathematical procedure within a GIS environment was used, in QGIS 3.32.2 software, relating population gridded and meteorological data to make the necessary calculations. In 2023, it estimated consumption for intake and personal hygiene of 4.7 Mm3, 6.3 Mm3 for 2033, 8.4 Mm3 for 2043 and 11.3 Mm3/year for 2053. In recent years there have been rainfall records throughout the Iishana system, at an average of 518 mm/annum, but high temperatures accelerate water evaporation. Due to the topographical conditions, the waters are drained by gravity to the south of the basin (Republic of Namibia), causing a greater shortage in the dry season on the Angolan side, the study targets the estimation of water demand and the concept of rainwater harvest and sustainable water infrastructure to supply safe drinking water to equalise water demand and reduce vulnerability to climate change. These early findings may provide a basis for developing sustainable water infrastructure and use plans to improve the livelihoods of the resident population within the basin.