Challenges and opportunities of sediment budgeting using the River Sediment Budget Approach (RSBA): Three cases in Austrian gravel-bed river reaches

Abstract

River sediment budgets are prepared globally, under different conditions and requirements. This paper proposes a general methodology for sediment budgeting – the River Sediment Budget Approach (RSBA), to demonstrate the challenges and opportunities involved in establishing a sediment budget. The methodological approach focuses on the bedload, suspended sediment load as well as changes in the river bed and morphology. Four approaches are provided for sediment budgeting, which can be used individually or in combination and are selected based on the time scale and data availability. If measurement data is available or can still be undertaken, a (i) field-based approach is selected. Specifically, the morphological changes or data required for formulas can be gathered using a (ii) GIS-based approach. When calculations are carried out without measured data, a (iii) formula-based approach is pursued. Due to the numerous budgets already conducted and sediment data already measured, an approach dependent on (iv) literature data and estimations can also be considered. Due to the complexity of sediment dynamics in rivers, strict rules are not beneficial in sediment budgeting and, to avoid misinterpretation, it is essential to validate the results.