Incremental, piecemeal reduction of the functional fluvial floodplain is a threat to sustainable flood risk management in Scotland. From a flood risk management (FRM) perspective, removal of functional floodplain will often increase flood risk elsewhere, for example by increasing water levels upstream or downstream. Floodplain loss also results in ecological loss.
Despite Scottish Planning Policy seeking to safeguard functional floodplain, there are a number of reasons for loss, including historical planning permissions, householder and agricultural permitted developments and the cumulative effect of small scale developments.
Climate change is expected to have a significant impact on flood risk. As the frequency and magnitude of heavy rain events increase in the coming years, it is likely the frequency and magnitude of fluvial flooding will also increase.
Based on a literature review this report sets out a possible method for estimating floodplain loss and corresponding flood risk impacts. The method uses:
- information from historical maps and aerial photography;
- other datasets (such as the locations of embankments per the SEPA Morphological Pressures Database); and
- terrain information (if available).
Together this can drive the SEPA national flood map models using different digital terrain data for different time periods (therefore representing change in the functional floodplain) and simulate floodplain loss over time.