Småvatten då och nu
en förändringsstudie av småvatten i Skåne och deras kväveretentionsförmåga
PedologyCartographyWetlandsNitrogenAerial photographySouthern SwedenRemote sensingGISGeomorphologyPhysical geographyClimatologyNaturgeografiGeomorfologiMarkläraKartografiKlimatologiEarth and Environmental Sciences
Wetlands play an important role in the ecosystem. They reduce the impact of flow flux in the drainage area, acts as upholder of biodiversity, as an esthetic and recreational component in the landscape and they have the ability to reduce nutrients such as nitrogen, and help preventing eutrophication in costal areas.The number of wetlands in Scania have, due to the intensified agriculture been reduced to maximize the area suitable for crops.However since the mid 80th the consequences of this has been acknowledged, and many wetlands have been restored.This master?s thesis aim to see what impact this development have had on wetlands in Scania over the last 60 years. And also look at some of those factors important for the efficiency of nitrogen removal in wetlands. During the process a detailed manual for inventories of this sort was created.The material used to execute the inventory of wetlands where aerial photographs over Scania from the 1940th, 1980th and 2000. 30 5*5km picture frames over Scania were randomly chosen and systematically scanned for wetlands using remote sensing. The wetlands were then onscreen digitalized in a GIS.Area and numbers were then analyzed along with some spatial features important for nitrogen retention, such as location in the landscape, land cover use and distance to the ocean.The results show that the number of wetlands was vastly reduced between the 1940th and the 1980th, and then a slight increase in 2000. Wetlands with the possibility to reduce nitrogen outflow were also reduced between the 1940th and the 1980th, but have its highest number today. The total area of wetlands however is higher today then in the 1940th. The area of wetlands with the possibility to reduce nitrogen outflow has been increasing throughout.The biggest change is found in small wetlands with an area less then 1 hectare.Wetlands have decreased in farmland but increased in grassland.Overall the study shows that the potential for nitrogen retention has been improved, but nutrients in costal water show no reduction in concentration.