Modelling impacts of climate change on hydrology of Latonyanda River Quaternary Catchment, Limpopo Province, South Africa

Abstract

The study assessed the impacts of climate change on hydrology of Latonyanda River Quaternary Catchment (LRQC). The Soil and Water Assessment Tool (SWAT) model played a huge role in climate change impact analysis because it helped in improving the understanding of climate change impacts on hydrology as well as in determining mitigation measures. Arc-GIS 10.7 model with a compatible version of Arc-SWAT interface was used to model the impact of climate change on hydrology of LRQC. The SWAT model set up for calibration and validation was done using historic data. The SWAT Output viewer was used to view model performance results. Model performance was assessed based on scatter plots, graphical fits and performance measures which include Nash Sutcliffe Efficiency (NSE), percent bias (PBIAS), and coefficient of determination (R2). Climate change projections from Conformal Cubic Atmospheric Model (CCAM) were used to forecast the impact of climate change on hydrology. The historical, near future and far future periods are 34 (1981-2014), 30 (2023-2052) and 30 (2053-2082) years, respectively. To determine trends on annual average flows and statistical significance for historical, near and far future, regression analysis was used. Regression analysis showed that significance levels of the p-value for historical, near, and far future annual flow trends is 0.010, 0.034 and 0.030, respectively. The model performance was good and acceptable with NSE, PBIAS, and R2 for both calibration and validation as 0.67 and 0.68, -9.3 and -13.4%, and 0.70 and 0.69, respectively. The findings of the current study show that streamflow amount is decreasing over time with annual average totals of 4.849, 2.340 and 2.051 m3/s for the historical near, and far future respectively. The results will aid in raising awareness to the community and municipality governing around LRQC. This study recommends venturing into smart development technologies to minimise the impact caused by climate change. Further climate change related studies should be conducted as there is a gap in ungauged catchments. The expansion of the current study to include land use impacts on hydrology is recommended.