Critical to these SWSAs are extensive grassland, forest, and wetland systems, drained by numerous streams and rivers. This collective set of high-altitude Ecological Infrastructure (EI) connects to the major rivers, in the semi-arid Lowveld. These upper catchments and associated ecological and built infrastructure are critical for downstream water security on which multiple towns, large rural communities, agricultural and tourism hubs and their associated economies are fully dependent. Further downstream, these rivers are important contributors of water flow (especially in winter) to the Kruger National Park and many adjacent private nature reserves. The Blyde Catchment in particular plays a critical role by increasing water quality and quantity in the lower Olifants system.