Visual comparison of spatial patterns of annual suspended sediment loads estimated by two water quality modelling approaches

Abstract

The Queensland Department of Environment and Resource Management is using the SedNet and E2 water quality modelling approaches to support government policy and natural resource managers in improving water quality. SedNet is designed to determine the long-term average annual sediment load, and does not deal with temporal variability. It includes hillslope erosion, gully erosion, and riverbank erosion, which enables land managers to undertake on ground works in areas of the landscape that generate disproportionate quantities of sediment. E2 is a daily time step model capable of modelling temporal variability in water quality as a result of management and/or climate changes. However, hillslope erosion, gully erosion, and riverbank erosion are not currently explicitly represented in E2 in which sediment generation is based on the concept of Event Mean Concentration (EMC) and Dry Weather Concentration (DWC) with user assigned values depending on factors such as land use, soil type, and topography. As a modelling framework, E2 is capable of housing alternative models for the same process. Both SedNet and E2 modelling approaches are based on node-link configuration of the stream network generated from pitfilled digital elevation models. This configuration allows the user to determine outputs from either model at any point of interest within the catchment