Quantifying the post-installation impact of offline ponds in Coatham Beck, Stockton, NE England

Flooding is one of the major risks in the UK, which is increasing due to climate change and increased urbanisation. The Environment Agency in the UK has predicted that 1 in 4 properties will be affected by flood risk due to river, sea or surface water flooding by 2050.  Traditional flood defences built to protect the receptors such as infrastructure and people in floodplain are facing more intense and frequent floods. Natural Flood Management (NFM) aims to reduce flood risk to downstream communities by implementing upland measures that slow and store runoff, complementing traditional flood defences. Field-based evidence of the effectiveness of different types of NFM features are limited. This research develops a field-based method to quantify the performance of offline runoff attenuation ponds. A dense hydrometric network comprising of 12 pressure transducers, 2 ultrasound flow probes, and a tipping-bucket rain gauge has been installed across the site Coatham Beck, NE England (April 2024–present). The study quantifies pond storage and evaluates reduction or delay in downstream peak flows. This study addresses the wider challenge of lack of empirical quantification on NFM features. Findings will inform the design consideration for building better offline ponds allowing the replicability of such measures of flood in wider scale mitigating the impact of future flood risk.