Abstract:
To effectively and efficiently assess water availability there is a need for good quality hydrological time
series data. Globally there is a dense decline in hydrological data, which makes it difficult to assess water
availability. Remotely acquired data can be an alternative data source. This study was conducted to assess
water availability using remote sensing in South Rukuru and North Rumphi River Basin. To assess the
water availability, a rainfall-runoff (soil moisture method) hydrological model was developed using the
Water Evaluation and Planning (WEAP) modelling software. The WEAP inputs included the Global Land
Data Assimilation System (GLDAS) climate datasets, Elevation data, and the Land Use Land Cover. The
observed stream flow data was used for calibrating and validating the WEAP model. A hydrological data
availability assessment was performed to check for gaps or missing data in the streamflow time series
data. Although there were missing data, but with the threshold set, all stations under study had a good
allowable overall data availability. The performance of the WEAP model simulation was assessed and the
monthly measured and simulated streamflow statistics showed a positive strong relationship (R2 = 0.81,
NSE = 0.81, IA = 0.95, KGE = 0.89 and PBIAS of -3.8) at station 7G18. Similarly, there was a very good
agreement between the monthly measured and simulated streamflow at station 7H3 (R2 = 0.94, NSE =
0.93, IA = 0.98, KGE = 0.85 and PBIAS of -9.3). The hydrological response showed that in months at
which the precipitation was at its peak in all the sub-basins, the water availability was also at peak. In
general, The WEAP model has demonstrated the capability of GLDAS datasets to be used to assess water
availability when there is insufficient, inconsistent or fragmented observed hydrological data.
