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Updated: Aug 6, 2026
12:44
Watershed Planning within a Quantitative Scenario Analysis Framework
Published on: July 24, 2016
A system dynamics approach to stormwater harvesting under increasing drought variability
Oseni Taiwo Amoo1, Motebang Dominic Vincent Nakin1, Akinola Ikudayisi2
1Centre for Global Change, Walter Sisulu University, Mthatha Campus, Eastern Cape, Mthatha, South Africa.
Iscience
|July 23, 2026
Summary
Stormwater harvesting (SWH) can significantly improve water supply reliability in South Africa's Eastern Cape, even during severe droughts. Optimized systems enhance drought resilience and reduce reliance on conventional water sources.
Area of Science:
- Hydrology and Water Resource Management
- Climate Change Adaptation
- Socio-hydrological Systems Analysis
Background:
- Eastern Cape, South Africa faces escalating hydrological stress due to increasing drought variability.
- Conventional water supply systems exhibit vulnerabilities under intensified drought conditions.
Purpose of the Study:
- To evaluate the potential of stormwater harvesting (SWH) as an adaptation strategy in the Mthatha River catchment.
- To assess the impact of drought variability on water availability and supply reliability.
Main Methods:
- Multi-index drought assessment to characterize rainfall patterns and drought severity.
- System dynamics socio-hydrological modeling to simulate water resource dynamics.
- Extreme value analysis to quantify drought event magnitudes.
Main Results:
- Erratic rainfall patterns and severe droughts observed between 2016-2019.
- Drought events (10-20 year return periods) associated with annual rainfall of 532-512 mm.
- Optimized SWH improved supply reliability by up to 35%, despite a 22-48% decline in harvestable stormwater during droughts.
- Integrated adaptation measures proved more effective than single interventions in reducing system stress.
Conclusions:
- Optimized stormwater harvesting systems enhance drought resilience in water-scarce regions.
- Factors like institutional trust and economies of scale drive SWH adoption, while financial and infrastructure constraints hinder it.
- Well-supported SWH can reduce municipal water dependence and improve overall water security.
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