Assessing the use of earth bunds as Natural Flood Management features

Nature based solutions to urban flooding have drawn growing attention in recent years as climate change models predict a catastrophic increase to flood-risk in the UK and around the world. The lack of systematic empirical evidence to support Natural Flood Management (NFM) initiatives still presents a key barrier to the widespread implementation of NFM techniques. The disconnect between practitioners and academics in the field also remains a central issue to be addressed to improve uptake and acceptance of NFM by landowners.

Urban centres in the Wear Catchment in Northeast England are substantially affected by flooding. In this study, we assess the effectiveness of several earth bunds in creating temporary storage of flood water in the upper catchment of the Wear. For this purpose, we assess flood storage frequency and record the impacts of flood storage on bund structure. Arduino-based water sensors in each of the five bunds record the frequency of flood storage, which is related to precipitation intensity and volume. Changes in soil hydraulic conductivity and soil chemistry are also measured throughout the year to assess changes in infiltration capacity as a measure of bund stability. Finally, vegetation surveys are carried out to gain insights on soil recovery after the installation of the bunds, providing a measure of suitability for the land to be used for grazing.

Working closely with the Environment Agency and the landowner, this work aims to develop an improved understanding on the importance of the design requirements and location setting for the installations. We hypothesise that the varying build quality and placing of the bunds in relation to the stream will directly impact the regularity with which the bunds become active storage. This project adds to the evidence base of NFM in the UK and is of direct consequence to practitioners around the world seeking to improve NFM methods.