Environmental challenges to operationalisation of South African rainfall enhancement

Abstract

Most of the atmospheric moisture in systems moving across South Africa leaves the sub-continent as the weather systems move out over the ocean, only a tenth of it falls on the landmass as rain. An increase in the efficiency of the atmospheric moisture delivery system by means of rainfall enhancement is therefore an attractive concept. Rainfall enhancement functions by either providing additional Cloud Condensation Nuclei or Ice forming Nuclei that will beneficially influence the precipitation formation process, improving the efficiency of moisture to rainfall conversion. Systematic South African research into rainfall enhancement started in the 1970s. The South African Rainfall Enhancement Programme (SAREP), initiated in the late 1990s, is the most recent in a series of studies and was the first semi-operational rainfall enhancement project to occur in South Africa as a response to drought conditions. In a recent study (DWAF, 2004) to finalise SAREP and provide guidance on operationalising rainfall enhancement, it was recommended that environmental impact assessment must be undertaken before this technology is implemented further. Rainfall enhancement falls specifically within the jurisdiction of the National Water Act (NWA) and the National Environmental Management Act (NEMA). A licence to undertake rainfall enhancement activities is required from the Minister of Water Affairs and Forestry after an appropriate environmental impact assessment has been undertaken to inform his decision. This paper proposes an approach to fulfil the legal requirements for operationalising future rainfall enhancement. The interaction between the science of rainfall enhancement and the ability of scientific disciplines to determine relevant environmental impacts, to appropriately inform the decision-making process, is specifically highlighted. The data requirements identified by scientists during the study varies in duration and resource needs and does not differentiate between ongoing scientific research and the requisite information required for informed decision making. This paper contemplates an approach which provides for holistic and co-ordinated investigation of South African rainfall enhancement into the future.