Abstract
Abstract. We investigate the impacts of land cover changes on the river flows of the Middle Zambezi tributary catchments in Zimbabwe. Trend analysis on rainfall and streamflow was carried out using the Mann-Kendall test at monthly and annual time steps. Rainfall analysis indicated an increasing trend which was not statistically significant (p<0.05) for all stations. Annual streamflow time series indicated negative decreasing trends which were not statistically significant (p<0.05) except for the rainfall months of November and December. The study deduced that the changes in rainfall did not affect hydrological catchment behaviour and changes in streamflow were thus caused by anthropogenic factors such as land cover changes. Statistical tests indicated a weak but significant correlation between rainfall and streamflow which also supports the fact that changes in streamflow are mainly driven by land cover changes. Land cover change assessments were done through supervised classification of Landsat images for the years 1989, 1998, 2008 and 2014. All catchments exhibited increases in cultivation area and decreases in forest and grassland. The semi-distributed HBV-Light model was applied for change detection modelling of the gauged Musengezi catchment. We conclude that the HBV Light model can be successfully used to simulate flows for the catchment.
Highlights
The Zambezi River Basin is the fourth largest African freshwater catchment and the largest river system in Southern Africa covering an area of 1.37 million km2 with a discharge averaging around 2600 m3 s−1 into the Indian Ocean (Beilfuss, 2012)
A reasonably good model performance with a Nash Sutcliffe Efficiency (NSE) of 0.61 was obtained using the land cover map of 2008 which were considered as the baseline conditions
Increasing but insignificant trends were observed in rainfall received over the studied catchments while decreasing insignificant trend were observed in streamflows
Summary
The Zambezi River Basin is the fourth largest African freshwater catchment and the largest river system in Southern Africa covering an area of 1.37 million km with a discharge averaging around 2600 m3 s−1 into the Indian Ocean (Beilfuss, 2012). The population of the basin is estimated at over 30 million (World Bank, 2010). The expected increase in population, increase in consumptive use, will be coupled with land use changes that may, in turn, have an impact on the flow regimes of the basin. The Middle Zambezi part of the basin in Zimbabwe is experiencing these increased pressures including increasing demands for water. It is necessary to investigate to what level these environmental pressures influence river flow changes and, to propose measures to mitigate negative impacts on river flow regimes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Proceedings of the International Association of Hydrological Sciences
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
