Land Drainage

13.08.13 Star Carr 008
An old drainage pot exposed at the surface of the peat near Star Carr. Natural wastage of peat soils is causing these to emerge from depths formerly 3ft 6″deep

The Carrs used to be much wetter in the past. In order to farm the land more effectively, in common with many lowland areas, they have been drained by the cutting of ditches and the laying of pipes under the fields. At one time these were dug by hand, which was a considerable endeavour and the history of drainage methods and their evolution makes a fascinating story in its own right.

Drainage is an active process and requires constant maintenance and periodic renewal. In the post-War period substantial government grants were made to encourage drainage and boost food production. Nowadays it is recognized that in some places re-wetting the land and farming less intensively can have environmental benefits. Stewardship grants can offset the reduction in farm income.

These days machines are used to maintain the dikes by periodically cleaning (slubbing) the accumulating silt and vegetation. In the winter months you may see the work of tracked diggers along the ditches, spreading the material pulled out along the top of the bank. Mechanical pipe-laying machines can also lay lengths of perforated plastic piping along a series of slot trenches across fields. These are called underdrains. Look out for the ends of the pipes poking out into the side of the ditches. In the old days terracotta pipes were laid by hand in similar fashion. In places where the peat has shrunk, as it tends to once drained, one can find pieces of these old ‘pot drains’ at the surface, sometimes where cattle have worked the ground with their hooves.

Land drainage is a precise business, needing accurate, detailed surveying of the land levels and adjacent ditches, an understanding of the seasonal rise and fall of water levels in those ditches, the gradients on the ditch-beds and plans drawn up of which way the under-drains will flow towards them. Periodically drainage has to be renewed. Perhaps every 2 or 3 decades. Either it becomes silted up and blocked or too shallow due to the loss of soils. Sometimes multiple generations of drains are evident. In places the excavation of wader scrapes for the wetland project revealed old terracotta ‘pot drains’ cross-cut by the gravel infill of a more modern plastic pipe drain, laid at greater depth and in a slightly different direction.

The old field drains, called by local farmers ‘pots’ or ’tile’ drains were dug into narrow trenches about a yard deep. The separate pots – open ended pipes in 1 foot lengths, were laid along the bottom. They were not sealed together, so the joins offered a gap for water to seep in from the ground. Straw was laid on top before the soil was back-filled, so that it didn’t wash straight into the pipes and block them.

Modern drainage is mechanised, with machines that in one pass can open a vertical slot to a precisely measured depth, then pay out into the base of it a continuous length of flexible perforated plastic pipe. Behind that a hopper full of coarse stone covers the pipe to a calculated depth, then the soil slot is closed over. All that remains visible on the surface is a line of disturbed soil. Where it meets the perimeter ditch, the last few metres of the pipe is unperforated, to form the outfall pipe that we see poking out, otherwise seepage would sap away the banks of the ditch. Once laid, the drain trickles out water from the furthest reaches of the field in a continuous flow all year round.

potato growing nr Seamer Carr
The deep, fertile peat soils of The Carrs, once drained, proved ideal for potato growing but heavy machinery can become bogged during wet harvests. Increasingly the area is turning to pasture for that reason.

Drainage is an integral and historic feature of lowland farms and wetlands with its own vocabulary. Ditches are variously named dykes, drains, gutters, delphs or cuts. There are many regional variations around the country. Key ditches often have names which are given on OS maps like Howlings Dike, Old Scurf and North Delph. When farmers refer to ‘drains’ they may mean the pipes under the field, or the ditches between fields. Equally the word Carr remains in many place names today, often long after they have been drained and ‘reclaimed’ for pasture or arable farming. See also What’s in a name? on the blog.

The local drainage board of The Carrs is called Vale of Pickering IDB  (IDB stands for Internal Drainage Board). Until recently it was the Muston and Yedingham IDB – originally set up following an act of Parliament in 1800, ‘The Muston and Yedingham Drainage Act’ with the objective ‘to drain the low grounds’ of the Hertford and Derwent rivers.  They have collected drainage rates from land owners and maintained the rivers and principle drainage ditches for over two hundred years. In 2014 three historically separate IDBs in the Vale of Pickering amalgamated, with a single board of members.

Renewal of Drainage – further examples.

The upgrading of defunct or ineffective land drainage can take place at any time, at the whim and (significant) expense of the landowner. It can produce quite dramatic changes. In my experience on The Carrs, where there is a patchwork of land ownership, some farm businesses were more pro-drainage than others and I would say generally that it was only deemed worthwhile for (more profitable) arable crops such as cereals or potatoes. Occasionally I saw new drains laid in improved pasture to raise the productivity (for grazing, silage etc.), but mostly it appeared that pasture on the Carrs was best suited to sheep and perhaps not worth the investment.

I saw some dramatic examples where new drainage was installed – because in order to put the new underdrains at a suitable depth and for them to function the outfalls had to be above water level in the receiving ditch. Thus the ditches themselves have to be first deepened (and widened otherwise they collapse in). I can show this with a before and after shot. They are from opposite angles, as I did not know that my before shot was going to be a before shot! But I’m almost certain they are the same length of ditch.

It is also fascinating to see examples of drainage plans produced when a renewal scheme is proposed. These are based on topographic surveys and show the spacing, number, depth and direction of the underdrains as well as the bed and water levels and flow direction of the surrounding ditches.


5 thoughts on “Land Drainage

  1. Pingback: Carrs Wetland -What’s in a Name? | The Carrs Wetland Project

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  3. Pingback: What’s in a Name? The Origin of the word ‘Carr’ | The Carrs Wetland Project

  4. Pingback: River channels new and old at Folkton Carr. | The Carrs Wetland Project

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