HEALTH, FOOD AND WATER SECURITY IN SOUTH AFRICA
Climate impact indicators
Global essential climate variables/indicators used
Monthly maximum and minimum temperature and precipitation for the 19 available Global Climate Models at 0.5 deg resolution for both the RCPs 4.5 and 8.5 scenarios for the 2011 – 2040 time period
Regional/local indicators used and produced
Median monthly changes in streamflow, changes in timing of flows.
Global data to regional/local scale
Step1: Data collection and model configuration. Using South African national sources of climate, land use and soils data (CWRR, UKZN Quinaries database), the existing configuration for the ACRU agrohydrological model for the uMngeni catchment was updated. The ACRU model was run in distributed mode, with 1003 hydrological response units, for each there was a climate file, land use, soils and streamflow response variables. For reporting purposes, those were clustered to 145 catchments and 13 Water Management Units (WMUs). Baseline historical scenarios were run (1960 – 1999) and the simulated streamflows compared to observed flows.
Step 2: Defining scenarios and CIIs.
Step2.a The CIIs for monthly maximum and minimum temperature and precipitation for the 19 available Global Climate Models at 0.5 deg resolution for both the RCPs 4.5 and 8.5 scenarios for the 2011 – 2040 time period for the grid cells within the uMngeni catchment were produced within C3S_422_Lot1_SMHI contract. These CIIs were calculated with bias adjusted CMIP5 data available in the CDS catalogue.
Step2.b The change factor method was used to further downscale the CIIs. The obtained monthly values of the CIIs were used as change factors and applied to the historical climate records to produce adjusted climate files for use in the ACRU agrohydrological model representative of the projected climate for 2011 – 2040.
Step3: Scenario modeling and analysis. The climate files representative of 2011 – 2040 were used as input to the ACRU model and simulations were undertaken for each of 19 GCMs for both the RCP 4.5 and RCP 8.5 scenarios. The outputs from the 2011 – 2040 simulation were compared to the simulated outputs from the historical baseline run. The modelled output compared included precipitation and streamflow at a monthly scale, both the mean and range of percentiles were compared.
Step4: Development of showcase. Following the analysis of the results, the showcase was developed. The showcase focused at the uMngeni WMU scale for ease of understanding. The historical and future (2011 – 2040) median monthly minimum and maximum temperatures, precipitation and streamflow for each of the WMUs were included. The potential impacts of these changes on water quality were interpreted and conveyed using an infographic.
Step5: Dissemination of results. The dissemination of the findings to the stakeholders has been through presentations at local meetings; distribution of links to the showcase to the relevant stakeholders; and distribution of a popular article on the showcase, findings and results to the relevant stakeholders.