Evaluating wetland flow regulating functions using discharge time-series

Abstract

This paper describes a parsimonious approach for the evaluation of wetland hydrological functions, based on continuous observed streamflow records and flow duration curves. The functions evaluated are baseflow maintenance and flood attenuation, jointly referred to as flow regulation. The first step in this evaluation is to establish a reference hydrological condition. This condition is defined in terms of mean daily and instantaneous daily maximum flow time-series and their corresponding duration curves, assuming that there is no wetland in the catchment. Further steps include calculating the changes of various flow percentiles, caused by the presence of a wetland, detailed hydrograph analysis, baseflow analysis and analysis of changes in characteristics of continuous flow events above and below specified threshold discharges. The method is illustrated using the observed streamflow data in the catchment of the Rustenburg wetland in South Africa.