“The Trust’s aim is to promote, protect and conserve the living landscape of the Ironbridge Gorge World Heritage Site”

Book onto one of our Outdoor Learning Programme courses and discover something new!

Book onto one of our Outdoor Learning Programme courses and discover something new!

27 exciting new walks, workshops and events

The Iron Trail

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Flooding and Land Management

The devastating floods in Cumbria and the North West have been awful to watch and, as an area prone to flooding we can empathise strongly with the local residents and businesses so badly affected. The media reports often only give part of the picture. So what causes these massive floods? Imagine that the ground is a sponge. Now sprinkle water on that sponge over a day and then keep on sprinkling and gradually the sponge will not be able to take any more water and becomes saturated. If you then sprinkle water onto the sponge at a much faster rate water will begin to pour out of it. In terms of land, how much water will pour out into the streams and valley will depend on the geology underneath the soil. If it is limestone for example, there may be large caverns and voids underground which can fill up with water thereby slowing the flood over a longer period. If the soil is clay over an impermeable rock then run off into streams will be very rapid. When rain falls it does so over a wide area at the head of streams and rivers called a catchment. If it has been raining for a prolonged period and the ground is already saturated then all that excess water from the catchment which may be hundreds of hectares in size flows straight into the streams and rivers, then into valleys filled with houses. To put the Cumbria flood into perspective, in Coalbrookdale our worst flood in recent times involved 68 mm of rain falling over a 36 hour period. A staggering 405 mm of rain was recorded at Thirlmere in the 36 hours to 6th of December and 341.4 mm recorded at Honister Pass, both breaking UK records! But this rain also fell heavily over a very large area of the catchment - see attached picture. Research at Pontbren in mid Wales has shown that if this rain falls onto sheep pasture in the uplands then the flood pulse is much faster than if it falls on 5% wooded ground which can reduce the flood peak by 29% or 50% if its fully wooded. However a word of caution is that this was based on trees planted ten years before and are a projected simulation. But it makes sense. If water is having to make its way through a maze of tree roots the soil will have more voids to store water. But the picture is very complex involving how much evaporation (water changing to a gas like the steam you see rising on a sunny day) and transpiration (plants and trees absorbing water through the roots and giving off water vapour through pores in their leaves) as well as abstraction (water taken out of rivers for our use) and rainfall is occurring in the catchment. It also depends on intensity of that rainfall. In the Boscastle floods 75 mm fell in only 2 hours onto saturated ground in the upper catchment. Other issues are ways to slow down the flood pulse over a longer period and there are examples of debris dams (trees felled across streams in the upper parts of valleys) such as the recent ones in Stroud. The challenge in the Ironbridge Gorge is that stopping the water in s

Continuous Cover

Work began in Sutton Wood alongside the River Severn East of Coalport this week working with contractor NW Tree Services. The work involves thinning through felling a number of ash, sweet chestnut and conifers to create a woodland of trees of mixed sizes under Continuous Cover Forestry principles. Looked at in 3D this means we will have smaller trees coming through ready to replace the larger ones and trees of many different heights allowing light to better reach the woodland... floor. This encourages tree seedlings through natural regeneration (why plant when you can have them for free and the deer like planted trees!) and a more diverse range of woodland plants. There are a number of oak trees in Sutton Wood that are being shaded by larger tree canopies above. When marking trees to be removed in a thinning you have to be able to imagine what holes you are creating in the tree canopy to allow light and space for the smaller tree to grow. Too big a hole and trees can blow down or bramble can swamp the ground, too small and there isn't enough light. Forestry is an art as well as a science!The pictures show a felled ash tree and a smaller oak tree from the perspective of looking up into the tree canopy with the new space that will encourage it to start growing. As it grows more trees around it will be removed. Restructuring the woodland to get the sizes and 3D correct will take at least 30 years work. As guardians of the 700 acres we manage we are aware that our work will benefit future generations. IMG_4553 IMG_4554.