Agricultural subsurface field drainage in Lincolnshire and its impact on sediment loading in Lincolnshire watercourses Mrs Snežana Lee, PhD Candidate Supervisors: Prof. Ron Bickerton, Dr Iain Gould and Mrs Isobel Wright Current state and novel solutions 24th Jan 2018

Problem Sediment loss Soil loss, Decline in soil fertility, health and productivity Diffuse pollution and water quality, Reduction of water holding capacity Source:https://www.woodlandtrust.org.uk/blog/2014/06/losing-ground/ In contrast to point source pollution, that is easier to control, diffuse pollution which is spread across the landscape is difficult to identify to start with, and its control is extremely challenging. Sediment loss is a major concern: Agricultural On-site (soil loss with its practical and economic implications) and environmental off-site impacts (sedimentation within surface water bodies, making them turbid, consequently reduces light levels which affect ecosystem function and carries sediment associated pollutants- the amount of particulate organic carbon associated with the sediment (chlorinated compounds including many pesticides)).

Problem Drainage systems Source: Sneska Lee , Lincolnshire (Jan 2018) Agricultural field drainage systems face major problems in their functioning, Partially or fully blocked pipes gradually degrade system’s operation capacity, Fields suffer from reduced drainage rates and waterlogging, Negative impact on soil function Surface runoff is a visible component of soil erosion. But subsurface drainage systems can also present an important runoff vector, consequently increasing hydrological connectivity of the landscape. Potentially they may have substantial impact on water quality. However, most of subsurface drainage system in the UK are considered old and in need of replacement. Compared to the period after the WWII and 70s and 80s, there was very little investment made to update the systems. Tile displacement, blockages, lack of maintenance makes them unfit for purpose.

Project outline Survey the current condition Laboratory work and modelling Field testing! Water flow Pipe Source: Sneska Lee, Lincolnshire (Jan 2018) Maps…help us identify areas most at risk of increased sedimentation and critical areas for the risk of flooding. Using these areas as a suitable case study zone 4) The design needs to provide sufficient residence time for the water to slow down its flow and allow suspended sediment to be trapped. This measure is cost effective and non-intrusive for the land owner, as all agricultural activities can continue.