Overview of water resource assessment in South Africa: Current state and future challenges

This paper reviews the progress made in the assessment of water resources in South Africa over the past 60 years by examining 5 major studies that were undertaken in this period. These studies illustrate how the exponential growth in computer power and the concomitant development of highly sophisticated tools have changed the manner in which our water resources have been appraised, allowing us to deal with more and more complex issues, including: water quality, surface water/groundwater interaction and the reduction in runoff due to afforestation and alien vegetation. However, the main concern today is the serious decline in hydrological monitoring in recent times. It is imperative that this decline be addressed, especially if we are to deal effectively with problems related to climate cycles and climate change, together with the deterioration in water quality.Keywords: rainfall, streamflow, water resources, water quality, land use, climate cycles, climate chang

Predicting the seasonal evolution of southern African summer precipitation in the DePreSys3 prediction system

We assess the ability of the DePreSys3 prediction system to predict austral summer precipitation (DJF) over southern Africa, defined as the African continent south of 15°S. DePresys3 is a high resolution prediction system (at a horizontal resolution of ~ 60 km in the atmosphere in mid-latitudes and of the quarter degree in the Ocean) and spans the long period 1959–2016. We find skill in predicting interannual precipitation variability, relative to a long-term trend; the anomaly correlation skill score over southern Africa is greater than 0.45 for the first summer (i.e. lead month 2–4), and 0.37 over Mozambique, Zimbabwe and Zambia for the second summer (i.e. lead month 14–16). The skill is related to the successful prediction of the El-Nino Southern Oscillation (ENSO), and the successful simulation of ENSO teleconnections to southern Africa. However, overall skill is sensitive to the inclusion of strong La-Nina events and also appears to change with forecast epoch. For example, the skill in predicting precipitation over Mozambique is significantly larger for the first summer in the 1990–2016 period, compared to the 1959–1985 period. The difference in skill in predicting interannual precipitation variability over southern Africa in different epochs is consistent with a change in the strength of the observed teleconnections of ENSO. After 1990, and consistent with the increased skill, the observed impact of ENSO appears to strengthen over west Mozambique, in association with changes in ENSO related atmospheric convergence anomalies. However, these apparent changes in teleconnections are not captured by the ensemble-mean predictions using DePreSys3. The changes in the ENSO teleconnection are consistent with a warming over the Indian Ocean and modulation of ENSO properties between the different epochs, but may also be associated with unpredictable atmospheric variability

Can CHIRPS fill the gap left by the decline in the availability of rainfall stations in Southern Africa?

Rainfall is the most important input to any hydrological or water resources study. The decline in the number of suitable rainfall stations since the 1970s is a cause for concern, plus there is an additional complication in that – for a number of catchments – mean annual precipitation (MAP), as derived from a recent study by Pegram, differs substantially from those adopted by the Water Resources of South Africa, 2012 study (WR2012) (mostly as derived by Dent). Rainfall data sourced by the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) satellite database was selected as a basis for comparison, both for catchment MAP and time series of monthly rainfall as used for input to the Pitman hydrological model (WRSM/Pitman, previously called WRSM2000). The analyses revealed that the WR2012 method of constructing the time series yielded the best results overall, but the difference was not marked, except in the winter rainfall region, where CHIRPS (and to a lesser extent, Pegram) performed poorly. It is concluded that CHIRPS will have a role to play in future water resources studies. It is recommended that the study be extended to cover a larger sample of catchments with up-to-date rainfall and that the possibility of CHIRPS data being recalibrated for the winter rainfall area be investigated

Hydrological and hydraulic modelling of the Nyl River floodplain Part 1. Background and hydrological modelling

The Nyl River floodplain is a seasonal wetland of great conservation importance in Limpopo Province, South Africa. Water resource developments in the upstream catchments are changing the quantity and timing of water delivery to the floodplain, and this is expected to have an ecological impact. Hydrological and hydraulic models have been developed to help assess this impact. This paper describes the calibration and application of hydrological models of the contributing catchments. The hydraulic modelling and scenario applications to predict changes to vegetation habitat associated with upstream developments are presented in two companion papers. Hydrological simulations were performed using two models, one using daily time steps and the other using monthly time steps. The models were calibrated using historical data on 10 gauged catchments. Their performance was similar in producing average monthly and annual flows, although the higher resolution daily model agreed more closely with the historical data. Simulated estimates of mean annual runoff values for individual catchments compared well with results from previous studies. The daily model also predicted acceptable measures of probability distributions of maximum annual daily flows and daily flows exceeding a specified threshold

DESA1002 'Continuous City' <Danielle Gardner>

My familiarity of the design process has been extended and I have found this semester to be a rewarding and worthwhile experience where I have been challenged and have begun to have a clearer understanding of the different approaches and techniques used in design and architecture. The exercises have been valuable with ongoing weekly research benefiting us with our independence in following up queries on our own and improving our critical thinking. The experience of presenting in front of a group of people in the design classes is an area that I needed to improve on and something that I have appreciated. At times I have found myself to be nervous and uncomfortable about having to express my opinions although doing this repetitively has enhanced my capabilities and given me confidence. I have enjoyed the experience of seeing a project through from the beginning, starting with the selection of an appropriate site and balancing up the options of orientation, site size, accessibility in order to come to an appropriate resolution. As I have progressed through I have changed my design in accordance with feedback and formed new ideas and concepts that eventuated through this design process