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The trust aims to improve river networks through working at the catchment scale beginning at the headwater reaches and then working down stream. At the upper reaches a number of issues impact on rivers including drianage, stocking rates, livestock access to river banks and nutrient inputs from slurry and fertilisers. The trust recognises that land management needs to be economically viable. This is vital to the landscape of the Yorkshire Dales which has been a working landscape for centuries. But there are still opportunities to improve land management in ways that do not imapct on farming incomes.
To start the issues within a catchemnt need to be idnetified. This is done through a mix of remote sensing, modelling and field surveys. These can then be mapped and the locations for further investigation highlgihted. In the dales some of the more serious issues include how moorlands have been managed in the past. Open drains, commonly known as grips, were cut into the moors to drain them allowing increased grazing. These effected the hydrology of peatlands and in places caused severe erosion and rapid spate events as water flused from the moors with greater rapidity. To compound this summer base flows have also been reduced due to this dranage. These effects have severely degraded the qualtiy of river habitats so that the ecolgy of the dales rivers has been degraded.
Figure 1 shows an area of grips that the trust mapped and later modelled using ArcGIS to see how they affect water flows. The bottom left image shows an area of the same moor that has been heavily eroded due to these grips. Natural England are now working with the landownwrs in order to develop a strategy for blocking the grips on this moor.
The trust works in partnership with other conservation organisations and directly with willing landowners and farmers to put in place simple management measures that break the connections between pollution sources and watercourses. These measures include grip blocking, buffer strips, contour planting and gill planting. These simple measures not only improve catchment and river biodiversity they protect the soil which is any farms greatest resource. It is through these win – win situations that river health can be improved.
SCIMAP
Excessive fine sediment in upland river courses can degrade the ecological condition of the river. Numerous land based activities can result in sediment erosion to water courses these include drainage, ploughing, poaching by livestock, changes in hydrological pathways and stream power. When the sediment reaches a water course it can smother Salmon and Trout spawning beds, reduce gill efficiency in fish and fly life and diminish light penetration and thus plant growth. All of these effects degrade the ecological condition of rivers and streams.
The Sensitive Catchment Integrated Modeling and Analysis Platform (SCIMAP) is a modeling tool that allows the identification of risk within a landscape resulting in fine sediment accumulation in watercourses. From landcover and rainfall maps coupled with a Digital Elevation Model (DEM) SCIMAP displays relative information on erosion risk, connectivity and sediment accumulation across a catchment. Moreover grips (upland drainage channels) can be added to the DEM and landcover maps to see how the resulting altered hydrology affects both connectivity and erosion risk. The flow chart below shows the data flow through the SCIMAP model.
 SCIMAP relies on a flow of data beginning with a DEM and a Land cover map. From this all other data
can be derived ending with a risk map of the catchment displaying connectivity x erosion risk coupled
with in-stream fine sediment concentration.
The final output is a model that can be overlaid onto Ordnance Survey maps. The model shows the watercourses that are delivering a disproportionate amount of fine sediment to the river network. Underlying this output is a second map that highlights the areas that are most likely to be 1) an erosion source and 2) connected to the river network.
The map below shows these outputs for the Skell/Laver catchment close to Ripon. The red watercourses are those that present a high risk of in-stream fine sediment moving through to green which represents low risk.  The grey areas beneath are those most likely to be the sources of in-stream sediment.
With modern processing power these models can be run at fine spatial scales allowing the identification of gills that would benefit from planting, where buffer strips would be most effective and which grips should be targeted for blocking. This allows enhanced connectivity to be reversed and a reduction in the sources of both erosion and fine sediment.
Such modeling advances provide powerful tools for restoration ecologists and in a world of finite resources, both natural and financial, these models provide excellent value.
References
www.scimap.org.uk
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