In collaboration with the Environmental Economics Network of Namibia, the De-bushing Advisory Service hosted an after-work seminar on the impacts of bush encroachment on groundwater recharge on 07th November 2018 at the NUST Hotel School. This follows 9 years of soil hydrological monitoring in a Namibian thornbush Savanna using automatic field monitoring techniques since 2007 by Dr. Alexander Groengroeft and his colleagues from the University of Hamburg. The aim of the research was to understand the influence of different vegetation cover on the processes of soil water uptake and losses as well as to understand the water consumption patterns of different vegetation types.
In his presentation, Dr. Groengroeft addressed three key questions on the impacts of bush encroachment on the water infiltration process, on consumption of soil moisture through evapotranspiration and on the potential deep percolation. “Our results have shown that encroaching trees such as Acacia Mellifera modify the local soil water balance substantially by reducing infiltration, which results in higher evapotranspiration and less deep drainage, said Dr. Groengroeft. Thus, the increase in tree density with the respective reduction of intercanopy areas is likely to negatively impact on groundwater resources. He concluded that further empirical research is necessary to analyse groundwater dynamics at large scale combined with consistent soil water monitoring at least for some of the dominant landscape types.