Estimating ground water recharge potential in Nakasongola District using wetspass model.
AYEBARE, Maxwell Bariyo
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Ground water recharge from rainfall in the Nakasongola is needed as an input for integrated ground water modelling in Nakasongola for more accurate sustainable development of water resources. The main objective was to estimate ground water recharge potential in Nakasongola District using the WetSpass model. Water and Energy Transfer between Soil, Plants and atmosphere under quasi-Steady State (WetSpass) model parameters were identified for Nakasongola based on the available meteorological data for the area collected in 2017 and 2018. The collected data were rainfall, temperature, wind speed and Geomorphological characteristics, such as soil type, ground water depth and slope, were also collected as input data for the WetSpass model. ArcGIS software was used to come up with land cover classification based on available sentinel 2 images of Nakasongola district for 2017, 2018 and 2019. Ground water recharge calculated using the water balance equation was compared to simulated ground water recharge and the results were used to calibrate the WetSpass model. The results indicated close agreement in ground water recharge between the two outputs with R2 of 0.8338 and 0. 0.8445, while the root-mean-square errors (RMSEs) were 0.446563 mm and 2.513411 mm for 2017 and 2018, respectively. The WetSpass model was then applied in respect of 2019 for the purpose of validation, the results indicated close agreement with R2 of 0.8161 and RMSE of 0.891558 mm. The results of the WetSpass model provide information to support integrated ground water modelling. The results reveal that WetSpass works well in simulating the components of the hydrological balance in the Nakasongola region. However, the results can be improved further by introducing a distributed storage component and also investigating the impact of soil moisture should be considered for future works as it plays a crucial role in the recharge process.