Using satellite-based rainfall data to support the implementation of environmental water requirements in South Africa

Abstract

The methods currently available in South Africa to implement environmental flows are based on real-time rainfall-runoff models (which require accurate inputs of rainfall data) or the use of flow gauges. Both methods are useful but have limita tions which must be fully understood. The main limitation of the latter approach is that there are few gauges that measure natural flow conditions in the country, and installing a new gauge can only provide information on the variability of flow characteristics after a very long period. The main limitation of utilising real-time rainfall-runoff models is that many of the rainfall stations that provided data in the past have recently closed down, while it is difficult to obtain real-time data from those that remain. The use of satellite data offers an effective and economical substitute to rain-gauge data for calculating areal rainfall estimates in sparsely-gauged regions.

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