Abstract
Abstract Study region Namibia. Study focus The lack of ground observations has long been a major obstacle in studying rainfall patterns in many dryland regions, particularly in the data scarce African continent. In this study, a continuous 6-year (2008–2013) daily record of ground observations collected from Weltevrede Farm at the edge of the Namib Desert was used to evaluate TRMM Multi-satellite Precipitation Analysis (TMPA, 0.25° resolution) daily rainfall estimates of this area. A Mann-Kendall trend analysis was conducted using all the available annual TMPA satellite data (1998–2015) to examine long-term trends in rainfall amount, intensity, frequency and seasonal variations over four locations across a rainfall gradient. New hydrological insights for the region The agreement between ground and satellite rainfall data was generally good at annual/monthly scales but large variations were observed at the daily scale. Results showed a spatial variability of rainfall trends across the rainfall gradient. We observed significant changes in frequency along with insignificant changes in intensity and no changes in total amount for the driest location, but no changes in any of the rainfall parameters were observed for the three wetter locations. The results also showed increased rainfall variability for the driest location. This study provided a useful approach of using TMPA data associated with trend analysis to extend the data record for ecohydrological studies for similar data scarce conditions. The results of this study will also help constrain IPCC predictions in this region.
Highlights
Rainfall is one of the main components of hydrologic cycle and the major source of water for natural vegetation as well as agriculture and livestock production in dryland regions (Wang and D’Odorico, 2008)
The opposite was observed on a number of low intensity rain days (e.g.,
We evaluated the feasibility of utilizing satellite-based rainfall estimates for examining the changes in rainfall patterns in data scarce dryland regions
Summary
Rainfall is one of the main components of hydrologic cycle and the major source of water for natural vegetation as well as agriculture and livestock production in dryland regions (Wang and D’Odorico, 2008). About 90% of the world’s dryland population is in developing countries (Wang et al, 2012), where the vast majority of drylands consist of rangelands (Millennium Ecosystem Assessment, 2005) (i.e., 69%). Dryland rangelands support approximately 50% of the world’s livestock and its production is vulnerable to climate variability, of which rainfall is the most important component (Millennium Ecosystem Assessment, 2005). Study of maize production in Zimbabwe indicated that more accurate climate predictions would be valuable in crop management decisions in that it reduced risk in agricultural production associated with rainfall variability at the site level (Phillips et al, 1998)
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