- 26th January 2022
- Posted by: Laura O'Connell
- Category: Blog
JBA has been working in the area of Natural Flood Management for a number of years, using natural processes to reduce flood risk. More recently we have been working with the Environment Agency assessing the potential water resource benefits of Working With Natural Processes (WWNP) and nature based solutions. In this blog, Susan Wagstaff, Technical Director, Hydrogeology, expands more on our work in this area.
Starting with a literature review of the interaction of working with natural processes measures and water resources we have identified the key roles of vegetation, soils and storage. To consider the interactions between WWNP and groundwater processes, we investigated areas of interest within ten Environment Agency priority catchments including site visits and engagement with local groundwater and water resource specialists. These catchments typically require more collaborative water management or have significant abstraction challenges. We have developed an understanding of how WWNP measures interact with specific soils, geology and hydrogeology environments and undertaken conceptualisation in a range of water resource situations. More details can be found here: Water Resources Priority Catchments – Environment Agency – Citizen Space (environment-agency.gov.uk).
WWNP work considers how changes to soil management, land use, woodland planting and surface water management features of various types (such as bunds) can change the pathways of water through a catchment. Measures to improve soil health which result in increased infiltration and reduced runoff have a significant potential to increase aquifer recharge. Measures that slow down water flow to reduce flood risk downstream result in ponding and can also increase infiltration to the ground. However, local geological and hydrogeological conditions are key in whether WWNP measures will translate into actual groundwater resource gains. Using GIS, JBA has mapped the potential for WWNP in priority catchments and are currently modelling these measures for the Otter catchment in southwest England. The modelling work is enabling the potential groundwater recharge gains from implementing WWNP to be quantified.
Working with Natural Processes: Key Processes throughout a Catchment
Whilst soil and land management improvement measures can be undertaken at all locations within a catchment, measures which interact with the drainage system are more specific to the location within the catchment as shown in this conceptual figure. The upper reaches of catchments have smaller drainage channels potentially suitable for measures to slow down and disrupt fast drainage pathways. These include blocking or partially blocking drainage channels and up-catchment storage measures. Mid catchments, with potentially steeper valley slopes, also allow for runoff storage and slowing of runoff, with the potential for channel reaches to lose water to the ground. Valley floor settings have a greater focus on restoring natural floodplain functions and potentially increasing storage of water in wetlands and valley sediments.
JBA is currently undertaking conceptualisation and mapping of nature based solutions within chalk catchments in East Anglia. This work is highlighting that the specific WWNP measures which are applicable in a catchment depend upon a detailed understanding of the catchment, including the underlying soils, geology and hydrogeology.
Want to know more?
For more information on the water resource benefits of working with natural processes, contact Susan Wagstaff firstname.lastname@example.org.