Kondolf Diagram for River Backwater Restoration

Rehabilitation, protection, and management of riverine backwaters (floodplain aquatic habitats that are seasonally or periodically connected to the main channel) are becoming increasingly common. General criteria for selecting restoration goals and evaluating alternative designs are lacking. An approach for assessing aquatic system status before and after restoration proposed by Kondolf and others (http://www.ecologyandsociety.org/vol11/iss2/art5/) is based on assigning a position to the system in a four-dimensional space that represents temporal variability on one axis and connectivity in the three spatial dimensions on the remaining three axes. Use of the Kondolf approach for evaluating restoration design for an example site is described. A plan featuring two small water control weirs was proposed, and a simple numerical water budget model was constructed to allow simulation of temporal variability and connectivity with the main river channel for any imposed annual hydrograph. The impacts of varying the backwater control structure (weir) design and its operation on Kondolf position were assessed using the model.