Limnology of the Touw River floodplain

Abstract

This report is the summary of a larger two-volumed work originally presented to the Coastal Lakes Working Group in 1981. The floodplain is in essence a series of small, shallow lakes, running in an east-west direction between the village of Sedgefield in the east and Wilderness in the west. They have been formed by segmentation of an earlier barrier lagoon associated with the Touw River. They have kept their connection with the Touw River estuary and so form part of its floodplain. The physical and chemical structure of the lakes is dominated by tidal influence when the estuary mouth is open and by erratic flooding of the Touw River and the Duiwe River, the latter flowing into Eilandvlei and which during floods is responsible for marked but short-lived pulses of phosphate and nitrate derived from agricultural activity on the upland catchment. Normally the lakes are pristine and constitute, together with their associated reed covered margins, an important wetland for a variety of animal forms, particularly birds. The aesthetic quality of this coastal region and the floodplain is under threat by the demands of human activity associated with urban development.