A catchment is the area of land drained by a river and its tributaries. It may include hill slopes and floodplains, lakes, forests, agricultural fields and urban areas. The Catchment Basesd Approach website has a map where you can find which catchment your location of interest is in. The four main catchments that drain into the Solent are, New Forest Rivers, Island Rivers, East Hampshire and the Test and Itchen.
Catchment Sensitive Farming (CSF) is a programme in England that aims to reduce water pollution from agriculture by providing farmers with advice and funding to implement measures that protect water quality in river catchments. The CSF program provides farmers with free advice on how to manage their land in a way that reduces the risk of water pollution. This includes advice on soil management, nutrient management, and pesticide use. It also provides funding to help farmers implement measures such as fencing off watercourses, creating buffer strips, and installing livestock drinking troughs away from watercourses. It is delivered by a partnership of organisations, including Natural England, the Environment Agency, and the Department for Environment, Food and Rural Affairs.
Nitrogen (especially nitrate) enrichment in some Solent estuaries has contributed to the excessive growth of green macroalgae on intertidal mudflats which can have adverse effects on ecology. Research by the Environment Agency on source apportionment has confirmed that the main sources of nitrogen (N) to Solent estuaries are diffuse sources from agriculture (on average about 50% N is from agriculture, often via rivers) and point sources from sewage discharges (on average about 10% N is from sewage). The remainder includes coastal background and urban sources.
The Environment Agency sets out Water Quality Priority Areas where Countryside Stewardship Agreements can help improve water quality. Incentives are offered to farmers to adopt agricultural practices which will safeguard areas and meet Water Framework Directive targets (see map for Solent priority areas).
The New Forest Nurseries project helps to address nutrient and sediment pollution from nurseries and soft fruit producers in the New Forest by providing expert advice from water resource management specialists and contributing funding for rainwater capture installations. Sites selected were based on WFD or Protected Areas failing or at risk, and for overall reduction of nutrients to water systems, and scale of interventions available to demonstrate good practice within the horticultural industry. Installation of rainwater harvesting tanks collecting from the largest roof surface on site were implemented at Beckheath Nursery (Lymington Catchment). Practical measures have been carried out at four sites located in three catchments, Lymington, Beaulieu and Sowley. Measures mainly included the installation of rainwater capture and storage linked to existing irrigation systems. Overall across these four sites the project has increase the water storage capacity from 120,000 litres to 580,000 litres, by fitting or upgrading guttering and pipework along roof space and installing large water tanks to store water which would other wash across hard surfaces and into the nearest water body.