Water quality management in the context of future climate and development changes: a South African case study

Abstract

Globally, water resources are being over-utilised; a situation exacerbated by degenerating water quality of rivers. To achieve sustainable management of water resources, uncertainty under climate change and development must be considered. A companion study was the first to incorporate uncertainty within water resources development scenario modelling for a catchment in South Africa using the Water Evaluation and Planning (WEAP) model. That study is extended in the current study by considering water quality in the form of nutrients and salinity. The WEAP model was calibrated against available observed data for the period 1999–2005. Using the calibrated WEAP model, driven by flow predicted using downscaled climate change models and projected future development, water quality was simulated for the years 2046–2065. Future simulations indicated marginally increased dilution capacity as well as increased nutrient inputs. It is evident that WEAP suffers major limitations in its water quality simulation capacity. Adaptive management along with continual monitoring as a strategy to cope with uncertainty associated with climate change and development is recommended. The shortcomings identified within WEAP in the current study were the motivation for the development of a new water quality decision support system specific to the requirements of water management in southern Africa.

Mapping and Assessing Riparian Vegetation Response to Drought along the Buffalo River Catchment in the Eastern Cape Province, South Africa

“…The Buffalo River Catchment is located between 33 • 39 ′ and 33 • 05 ′ S and longitude 27 • 05 ′ and 27 • 33 ′ E spanning 1237 km 2 on the east coast of South Africa in the Eastern Cape Province (Figure 1), with an approximately total population of 642,000 inhabitants [27]. The Buffalo River estuary enters the Indian Ocean in the city of East London with the catchment drained by the Buffalo River and runs southeastward towards the Indian Ocean with an elevation of 1200 mean sea level (3900 ft) [25]. The geology of the area is mostly made of marine sediments of the Beaufort Series with the Buffalo River being naturally saline [34].…”

“…Rainfall varies from the mountainous landscape and natural forest to the plain in the Northwestern to Southeastern direction [26]. In general, the average minimum temperature is 13.5 • C and can be as low as −3 • C in winter at the hilltop [25]. The average maximum temperature is 22.3 • C across the area while maximum summer temperatures reach 38 • C on the plain, especially at Gwaba town of the Buffalo River catchment [25].…”

“…In general, the average minimum temperature is 13.5 °C and can be as low as −3 °C in winter at the hilltop [25]. The average maximum temperature is 22.3 °C across the area while maximum summer temperatures reach 38 °C on the plain, especially at Gwaba town of the Buffalo River catchment [25]. Buffalo River catchment has four dams which are located from north to south comprising the Maden Dam, Rooikrans Dam, Laing Dam and Bridle Drift Dam with a full supply volume of 101 million m 3 [28].…”

“…Assessment of riparian vegetation response to water stress in a semi-arid environment especially along river networks is still lacking at the microscale level over a long-term period [22][23][24]. Only a few studies have explored the Buffalo River vegetation change placing limited emphasis on comprehensive riparian vegetation assessment to reveal the topographic complexities along the catchment dynamics because drought conditions are linked to multiple factors [25][26][27][28]. The complexities in interactions between drought and river hydrology necessitate a comprehensive approach that combines advanced remote sensing techniques to accurately assess riparian vegetation response to drought.…”