Tuesday, 11 October 2016

Farming and flooding - investigating common ground


Payments to farmers are currently under review as a result of our forthcoming departure from the EU.  It will ultimately be up to the UK government to decide what farmers get paid, or more importantly perhaps, what they get paid for.  Leaving aside the production of abundant, affordable and nutritious food, what do UK tax payers expect from farmers in return for their financial support?

Through the life of our EU membership, wildlife conservation has been a primary focus for agri-environment schemes, and this continues to be a major concern for a substantial proportion of the population.  Landscape is another.  An abundant supply of clean drinking water is a fundamental requirement of the population as a whole and becomes increasingly challenging as that population increases, and changes in rainfall patterns influence reservoir storage.  Most recently though, it has been the frequency of major flood events that has risen up the popular and political agenda.

Farmers are also concerned about the increased frequency of intense storms in recent years.  Apart from the flooding of low lying farmland, intense storm events cause water-logging and compaction of soils which, in turn, result in deterioration in soils, increases in weed burdens, reduced crop yields, and increases in input costs.  All of this reduces both farm profitability and the production of our food.  Getting water off the land through improved drainage is an increasing priority for many farmers.

So what can farmers do to reduce, rather than accentuate flood risk downstream?  Over the next five years, we will be addressing this question as part of our research in the Water Friendly Farming project, a landscape scale experiment with the Freshwater Habitats Trust which started in 2012 and involves three headwater catchments. 
Diagramatic representation of headwater ditch or small stream showing the two opportunities for controlling flow during storm events - optimising soil management to improve its buffering capacity, and creating permeable timber dams.




While effective drainage on our clay soils is essential, there is scope to improve the water holding capacity of the soil above the level of the field drains.  Improved soil management that reduces compaction and increases organic matter and biological activity improves conditions for crops, but also increases the capacity of the soil to hold water when it rains. Even greater benefits can arise from reduced soil erosion because of the associated reduction in sedimentation of drainage channels downstream.  This is all very much easier to say than to achieve in practice, but we are providing farmers with whatever support we can to help them achieve this over the coming years.  In doing so, we can draw on our own practical and research experience at Loddington, and on specialist advice from others.

We have already been surveying some fields for soil compaction, organic matter and earthworm abundance, all of which influence both flood risk and crop performance, and sharing this information with farmers.

Recently constructed permeable dam in the Water Friendly Farming project study area
There is also scope for holding back water in ditches and small streams by using permeable dams.  Such dams can often be relatively simple to install and permit water to flow normally uderneath them for most of the time, but hold it back when the water level rises during heavy rain.  Retaining water in headwaters, even if only for a couple of hours, can reduce flood risk downstream.  We have just started installing such dams in one of the two treatment catchments in our Water Friendly Farming study area, using locally sourced timber and a local contractor. 

We are using a combination of hydrological modeling by Colin Brown at York University, on-site observation, and guidance from catchment farmers to inform the siting of the dams.  The objectives are always to maintain base flow, optimise water storage during storms, and avoid impacts on productive land.
Over the coming years, we will continue to provide whatever support we can to help farmers in the study area to improve soil management, and we will install permeable dams where it is feasible and effective to do so.  By continuing to monitor flow at the base of the three study catchments, and comparing these data with data already collected as part of our ongoing research, we will be able to evaluate the effectiveness of this approach in terms of reduced downstream flood risk.  Such data, and our experiences along the way, will help to inform the development of policy that enables farmers to be rewarded for carrying out work on their land which has benefits for people living far beyond the farm boundary.

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