Methods developed to determine the amount of water required (EWR) to sustain ecosystem services in non-perennial rivers need a different approach to those used in perennial rivers. Current EWR methods were mostly developed for use in perennial rivers. Non-perennial rivers differ from perennial ones in terms of variability in flow, periods of no-flow and related habitat availability. A DRIFT-ARID method (an adaptation of the Downstream Response to Imposed Flow Transformation (DRIFT) method) was developed, tested and adjusted, using the semi-permanent Mokolo River. Field data from five study sites was collected from April to May 2010 by a multidisciplinary team. The results were used in a DRIFT-ARID Decision Support System (DSS) to determine the impact of five chosen development scenarios in the Mokolo River Catchment. An integrated groundwater-surface water MIKE-SHE hydrological model was used to simulate the hydrology of the chosen scenarios. Specific non-perennial river indicators such as onset of dry phase were identified and included in the DRIFT-ARID DSS. DRIFT-ARID has the potential to be used in non-perennial rivers and, once set up, can provide results for future scenarios. The method now needs to be tested on other non-perennial river types, especially episodic rivers where data are scarce or non-existent.

Environmental water requirement (EWR) assessment methods, for ascertaining how much water should be retained in rivers to sustain ecological functioning and desired levels of biodiversity, have mostly been developed for perennial rivers. Despite non-perennial rivers comprising about 30-50% of the world's freshwater systems, data on their hydrology, biota and ecological functioning are sparse. Current EWR assessments require hydrological and other data that may not be available for such rivers and some adaptation in the methods used seems necessary. DRIFT is an EWR method for perennial (or near-perennial) rivers that has been developed in South Africa over the past two decades and is now widely applied nationally and internationally. When applied to the semi-permanent Mokolo River, challenges particular to, or accentuated by, non-perennial rivers included the reliable simulation of hydrological data, the extent of acceptable extrapolation of data, difficulties in predicting surface-water connectivity along the river, and the location and resilience of pools, as well as whether it was possible to identify a reference (natural) condition. DRIFT-ARID, reported on here, is an adaptation of the DRIFT approach to begin addressing these and other issues. It consists of 11 phases containing 29 activities.

The impacts associated with unconventional oil and gas (UOG) extraction will be cumulative in nature and will most likely occur on a regional scale, highlighting the importance of using strategic decision-making and management tools. Managing possible impacts responsibly is extremely important in a water scarce country such as South Africa, versus countries where more water may be available for UOG extraction activities. This review article explains the possible biophysical and socioeconomic impacts associated with UOG extraction within the South African context and how these complex impacts interlink. Relevant policy and governance frameworks to manage these impacts are also highlighted.

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Some of the most important issues surrounding unconventional oil and gas (UOG) extraction are the possible impacts of this activity on potable groundwater resources and how to minimise and mitigate such impacts. A groundwater vulnerability map for UOG extraction has been developed as part of an interactive vulnerability map for South Africa in an effort to address such concerns and minimize possible future impacts linked to UOG extraction. This article describes the development of the groundwater theme of the interactive vulnerability map and highlights important aspects that were considered during the development of this map, which would also be of concern to other countries that may plan to embark on UOG extraction. The policy implications of the groundwater vulnerability map for managing UOG extraction impacts is also highlighted in this article.