Establishment and restoration of riparian buffers

Vegetated and unfertilized buffer zones alongside watercourses can significantly contribute to improve micro-climatic conditions, they act as a shield against overland flow from agricultural fields by reducing the run-off of sediments and pollutants reaching the watercourse and increasing groundwater recharge, and they contribute to reduce vulnerability to floods. A general, multi-purpose, riparian buffer design consists of a strip of grass, shrubs, and trees between the normal bank-full water level and cropland. Riparian Buffer Strips are linear bands of permanent vegetation adjacent to an aquatic ecosystem intended to maintain or improve water quality by trapping and removing various nonpoint source pollutants from both overland and shallow subsurface flow. Buffer strips also provide (additional) habitat for aquatic species and may result in increased recharge of groundwater.Riparian areas with trees also provide direct shade for the water body, reducing the influx of solar radiation on it and thus avoiding the corresponding increase in water temperature. In the case of wide riparian wooded areas (i.e. over several tens of meters), these can also increase the relative air humidity, which also contributes to a reduced temperature. This measure is considered particularly relevant for headwaters, with influence on water temperature and related biological processes which extends to downstream regions. Riparian buffers may be constituted by any type of vegetation along riverbanks, lakeshores, or other adjacent land to other surface waters. Wooded riparian areas are, however, more widely advocated as an effective way to provide water protection.Buffer strips are being widely supported as agri-environmental measures in European rural development programs. A typical value for buffer strips’ width is around 5 m. Wider buffer strips, which provide additional protection but used to be considered too costly, are finding additional support: a new option of the English Environmental Stewardship program supports 12 m wide buffer strips for watercourses on cultivated land. Based upon fish migration criteria the recommended width of a buffer is 10 m for upland streams and 100 m for lowland.Vegetated buffer strips can also be considered as strategies to protect coastal dikes, thus contributing to cope with the impacts of sea level rise. Like dunes, also wooded salt marshes in front of dikes have the potential to lower the wave load on the embankment. These areas may fulfil this flood protection function only when they can fully benefit from the hydrodynamic processes that ensure the supply of sediment and vegetation is able to develop without disturbances. Salt marshes reach their greatest extent along low-energy coasts where wave action is limited and mud can accumulate.