In agricultural areas, nutrient loads on surface waters might result in environmental standards being exceeded.
Clean surface water in the Northern Frisian Woodlands
For European Union countries, it has become especially relevant to adequately quantify these loads in view of the adopted Water Framework Directive. Not all nutrients that are removed at pedon-level by overland flow directly move into fresh-water systems. In heterogeneous landscapes, some features act as storage-structures for nutrients, dependent on the time-scale considered. Spatio-temporal analysis of transport-mechanisms has shown that some landscape elements may act as temporary (seasonal) storage structures for nutrients whereas others are showing a more permanent character. Because of this, removal of nutrients by overland flow at pedon level cannot be simply upscaled to the landscape level.
Heterogeneous landscapes with small fields (approx. 2 ha.) could up until now not be detected in digital elevation models because of limited resolution. Hence, within-field storage possibilities and redistribution-processes at the landscape level could not satisforily be analyzed. Newly available data-sets however currently do provide this opportunity.
A GIS study was performed for an area in the Northern Frisian Woodlands to quantify this degree of storage at the landscape level. Its landscape is classified as a “till landscape” with many small ponds (pingo ruins) and depressions. Soils are predominantly in use for agriculture, mostly dairy farming systems. Using a high-resolution DEM, digital soil maps, land use maps and spatially explicit hydrological data sets, an analysis was performed at the type, amount and spatial distribution of storage elements at the landscape level. The different hydrological systems, land use history and actual nutrient management at the existing farms were taken into account.
- Sonneveld, M.P.W., Schoorl, J.M., Veldkamp, A., 2006, Mapping hydrological pathways of phosphorus transfer in apparently homogeneous landscapes using a high-resolution DEM: Geoderma, 133: p32-42
» more LAPSUS Publications.