Groundwater as an emergency source for drought mitigation in the Crocodile River catchment, South Africa

Abstract

Abstract. Global climate change has received much attention worldwide in the scientific as well as in the political community, indicating that changes in precipitation, extreme droughts and floods may increasingly threaten many regions. Drought is a natural phenomenon that causes social, economical and environmental damage to society. In this study, we assess the drought intensity and severity and the groundwater potential to be used as a supplementary source of water to mitigate drought impacts in the Crocodile River catchment, a water-stressed sub-catchment of the Incomati River catchment in South Africa. The research methodology consists of three parts. First, the spatial and temporal variation of the meteorological and hydrological drought severity and intensity over the catchment were evaluated. The Standardized Precipitation Index (SPI) was used to analyse the meteorological drought and the Standardized Runoff Index (SRI) was used for the hydrological drought. Second, the water deficit in the catchment during the drought period was computed using a simple water balance method. Finally, a groundwater model was constructed in order to assess the feasibility of using groundwater as an emergency source for drought impact mitigation. Results show that the low-rainfall areas are more vulnerable to severe meteorological droughts (lower and upper crocodile). Moreover, the most water stressed subcatchments with high level of water uses but limited storage, such as the Kaap located in the middle catchment and the Lower Crocodile sub-catchments, are more vulnerable to severe hydrological droughts. The analysis of the potential groundwater use during droughts showed that a deficit of 97 Mm 3 yr −1 could be supplied from groundwater without considerable adverse impacts on the river base flow and groundwater storage. Abstraction simulations for different scenarios of extremely severe droughts reveal that it is possible to use groundwater to cope with the droughts in the catchment. However, local groundwater exploitation in Nelspruit and White River sub-catchment will cause large drawdowns (> 10 m) and high base flow reduction (> 20 %). This case study shows that conjunctive water management of groundwater and surface water resources is necessary to mitigate the impacts of droughts.

Hydrological Drought across Peninsular Malaysia: Implication of drought index

“…Due to the study's location in a humid tropical climate, it is also assumed that groundwater replenishment occurred during the early stages of drought events. The shorter period of the event can be explained by referring to results suggesting that the primary cause of the event was the higher demand for water during the dry spell (Mussá et al, 2015).…”

Research Trends of Hydrological Drought: A Systematic Review

“…Hydrological indices and low flow analysis have been used extensively and are a suitable method at the planning level of water resources development and management [53]. Some researchers have been developing a hydrological indices method that provides a specific spatial and temporal comparison of hydrological requirements [54][55][56][57][58][59][60][61][62]. Drought indices are significant features of monitoring and evaluation of drought as they simplify interrelationships between many climate-related parameters in terms of their intensity, duration, frequency and spatial extent [63].…”

Improved Hydrological Understanding of a Semi-Arid Subtropical Transboundary Basin Using Multiple Techniques – The Incomati River Basin

“…Exploitation of this resource could affect the base flow in rivers transecting this aquifer system (JIBS, 2001). Mussa et al (2015) conducted a study of groundwater as potential emergency source to mitigate droughts in the Crocodile subcatchment. The study characterized drought severity in the Crocodile using meteorological and hydrological drought indicators.…”