Variations in Peak Flow Behaviour, With Reference to the Eddleston Water, Scotland

Abstract

The Eddleston Water Project is a flagship natural flood management (NFM) project located in Scotland. Within the catchment there is a high density of streamflow and rain gauges that collects a high level of detailed data. Using this data the hydrological variables of time to peak, time for recession, event duration and lag have been analysed for unimodal events. Nine subcatchments of the Eddleston Water have been used to ascertain whether hydrological variables and hydrograph shape can be attributed to catchment characteristics. Examining hydrological changes after the introduction of NFM measures, time to peak was found to be the most statistically significant difference (p < 0.05) between the period before and after NFM. Out of the six catchments with flow data for analysis, Craigburn, Cowieslinn, Middle Burn and Shiplaw Burn all returned values of p < 0.05. The four catchments provided an average increase of 2.06 hours. All of these catchments were subject to some combination of construction of flow restrictors, ponds, wetlands and riparian planting. Two other catchments subject to riparian planting only did not show any significant change. Upper Burnhead (with water level data only) also provided a significant result (p < 0.05) for lag. Although not many significant results were found for the hydrological timing variables an increase in these were found from the period before NFM to after NFM with some catchments seeing increases of 30 minutes in time to peak, three hours in time for recession, four hours in event duration and one hour in lag. Mean annual flood decreased by up to 3 cumecs in some catchments. In conclusion, strong links have been demonstrated between catchment physical descriptors and hydrological response variables, and significant changes have been shown to accompany the introduction of NFM interventions. The future of NFM looks promising with these results, and continued efforts to further understand the behaviour, both empirically and using hydro-dynamic modelling, will yield wide impacting results for the literature, building on the strong empirical focus of the Eddleston Water Project.

Date of Award	2023
Original language	English
Awarding Institution	University of Dundee
Supervisor	Andrew Black (Supervisor)