BORROWDALE VLEI/WETLAND HYDROLOGICAL REPORT

17 JANUARY 2014

Augur Investments

OBJECTIVES OF THE PROJECT The objective of the project was to evaluate the hydrological and groundwater recharge impacts of the construction of the Borrowdale West Multi-purpose Park (BWMMP). Specific terms of reference To describe the hydrological characteristics of the catchment where the BWMMP is situated To describe the impacts of construction on the runoff characteristics of the area before and after construction To assess the Groundwater potential before and after the construction To give recommendations on balancing protection and development KEY FINDINGS · The hydrological area is in this work referred to as the Gwebi Upstream or Upper Gwebi catchment that falls under hydrological zone CH4 · The study was carried out using two scenarios for wetland conservation · The development on the site will increase the catchment impermeable surface from 40% to 60% in the best case scenario · The best conservation scenario entails that 60% of the project site will be utilized together with other conservation practices such as planting of trees, restoration of the wetland function and avoiding fragile areas. · The study showed that the best conservation measure scenarios should be implemented as it does not introduce a significant change to the area in terms of runoff regimes and it maintains some essential ecosystem functions. · Direct groundwater recharge potential under the best case scenario will be reduced from supplying 607 people to 243 people per year · Conservation and monitoring measures are to be implemented so that the loss in direct recharge can be mitigated. · There is a 3.5 % increase in the runoff volumes of the tributary to Gwebi River due to an increase in the impervious surface area but the time of peak (which is the time it takes for the rainfall events to reach a peak at the point of measurement) is approximately the same. · The worst case scenario (used only for modelling purpose) envisages the utilization of the area to 100% without any conservation practices. · The worst case scenario will significantly reduce the recharge potential and key hydrological processes like infiltration and percolation will be compromised Recommendations · The project owners should adopt the best case scenario which balances development and catchment protection. · The project owners should actively implement conservation practices in consultation with relevant stakeholder authorities so that there is synergy between the various elements of this hydrological system. · The mitigatory measures include proper engineering designs that will allow some form of artificial recharge. · A well/borehole should be put on the site in consultation with relevant authorities to monitor fluctuations in the water table so that responsive strategies can be implemented. · HydroResources Consultants to be your Environmental and Hydrological consultants in all issues to do with Environmental Monitoring and Sustainable utilization of the land and water resources at the site and other future related projects NB: Refer to the detailed submitted document for more clarification on the methodologies and finding.