The Potential for Dams to Impact Lowland Meandering River Floodplain Geomorphology

Table 3

Floodplain alterations from reference condition based on eight scenarios with the following variables: (1) 1 upstream dam; (2) 1 upstream and one midcatchment dam; (3) irrigation flows; (4) water supply flows; (5) dammed tributaries; (6) undammed tributaries. (A) The available floodplain area may be reduced by reservoir inundation, whilst the active floodplain will be reduced by lowering the area of flood extent. (B) Morphology may be altered by changes in the equilibrium between deposition and erosion. (C) The sedimentology may vary in rate, size, and also patchiness (or homogeneity) in both the cross and longitudinal profile of the floodplain. (D) The impact length downstream is used as a multiplier for (E) to weight the sum of A + B + C and then ranked from 1 (highest) to 8 (lowest) to denote modification from reference. The degree of confidence of each impact is rated None, Low, Medium, and High, based on the scientific understanding of the processes involved and also the cumulative impact of multiple dams, on both the main-stem and tributaries.