Mapping Risk to Water Quality from Space

A large amount of the water we drink comes from rivers and reservoirs. Although this water passes through complex treatment processes to make it safe to drink, the time, effort and cost of these processes depends on the quality of the raw water.

Human activities, in particular farming, can affect water quality by increasing the risk of soil mobilisation. For example, when arable land is tilled, soil is exposed. These bare soil fields present a higher risk of both erosion and diffuse pollution when compared to land which has vegetation cover.

We have been working with Anglian Water to identify areas of bare soil and model the risk they present to water quality. This negates the need for extensive and costly ground surveys supporting better management of resources and providing evidence for mitigation activities at farm scale such as planting buffer strips, growing cover crops or moving gateways.

A large portion of the region Anglian Water manages is used for large scale commercial agriculture. As a result, fields of bare soil
are common throughout the year. However, some bare fields will present more of a risk to water quality than others. The factors that influence risk include:

• Distance/proximity to river network:Bare fields in close proximity to a river network present a higher risk than fields further away because the soil has less distance to travel before it reaches the river.
• Slope: Bare fields that drain more steeply present a greater risk of soil erosion since they have a higher risk of soil mobilisation.
• Soil type: Fields found in areas where the soil type is more vulnerable to mobilisation will present a higher risk of soil erosion if bare.
• Vegetation: The vegetation found both within a field and between a field and the river network will affect the risk to water quality. Vegetation protects soil from erosion by preventing direct impact from rainfall, slowing down overland flow (reducing its erosive power), trapping sediment and stabilising the soil profile via the root network. Fields that have lots of vegetation between them and the river network are of a lower risk.

We are using Environment Systems Data Services and our Earth observation analytics to model water quality risk in near real-time for the Heigham catchment in Norfolk. This information is delivered to Anglian Water in the form of an interactive Business Intelligence Dashboard, which supports analysis via the visual representation of often very complex data. The dashboard has proved a success and we are currently working with Anglian Water to roll it out to other catchments.