The Influence of Rainfall Variability on Vegetation Dynamics in Okavango Basin

The Okavango basin is an endorheic basin which lies between Angola, Namibia and Botswana. It is the only perennial water source for Namibia and Botswana. Okavango delta is now a popular tourist attraction because it serves as permanent /seasonal habitat to wide variety of animals. As the demanding for water from both Namibia and Botswana keep increasing, more efforts need to be provided to balancing the needs for both human society developing and preserving habitats of wild variety of animals. The research on variation of available water resources in Okavango delta becomes more crucial. Most of the water drains into the delta are contributed by Angolan highlands. The inter- and intra-annual dynamics of precipitation in Angolan highlands significantly influence the water resources of Okavango delta. This study aimed to reveal how rainfall would influence the vegetation in Okavango delta, as well as to analyze the impact of rainfall variability on the vegetation dynamics. The remote sensing products filled the gap that few in-situ precipitation observations exist within this area. The correlations between rainfall and vegetation were analyzed based on the satellite estimated rainfall spatial distribution data (ARC2) and the NDVI series (AVHRR+MODIS). This study proposed a new method for rainfall-vegetation relations analysis in floodplains by combining the rainfall and flood from upstream river with a simple GIS spatial analysis approach. The influences of the variability of rainfall on vegetation dynamics were investigated and the impact of water lateral transport was highlighted in the research. Hot spots for vulnerable vegetation area in the Okavango delta were identified based on the analysis results. The research result could guide the wetland conservation efforts of Okavango delta.