Journal of Geographical Sciences ›› 2011, Vol. 21 ›› Issue (3): 417-428.doi: 10.1007/s11442-011-0854-5

• Hydrology and Water Environment • Previous Articles     Next Articles

Spatio-temporal ephemeral streamflow as influenced by climate variability in Botswana

Nnyaladzi BATISANI   

  1. Department of Agricultural Engineering and Land Planning, University of Botswana, Gaborone, Botswana
  • Received:2010-04-28 Revised:2010-07-20 Online:2011-06-15 Published:2011-06-15

Abstract:

The fourth assessment report of the IPCC highlights that the global average surface temperature is projected to increase by 1.8 to 4.0 by the year 2100 compared to ℃ current climate. Given that climate is the most important driver of the hydrological cycle, the rise in temperature could cause changes in occurrence patterns of extreme hydrologic events like streamflow droughts. An increase in frequency and severity of these events could pose serious challenges for sustainable management of water resources particular in arid regions. However, the understanding of water resources dynamics and the possible impacts of climate change on these dynamics is hindered by uncertainties in climate change models and complex hydrological responses of streams and catchments to climatic changes. Therefore observational evidence of streamflow dynamics at the local scale could play a crucial role in addressing these uncertainties and achieving a fuller reconciliation between model-based scenarios and ground truth. This paper determines spatial and temporal changes in streamflow volumes and their association with climatic factors based on the non-parametric Mann–Kendall test and ANOVA to determine possible changes in streamflow over the years and their relation to climatic factors. Streamflow is generally stochastic highlighting the importance of factoring in temporal flow variability in water resources planning. There is no clear evidence that changes in climatic variables are related to streamflow behaviour.

Key words: Botswana, streamflow, climate change, water resources, trend analysis