Impact of land use on water quality in the upper Nisa catchment in the Czech Republic and in Germany

Land use is one of the important factors affecting the water quality in catchments. This study evaluates differences in water quality due to land use in the upper transboundary catchment of the river Nisa (694 km(2)) in the Czech German-Polish triangle. Water samples collected weekly from the river and its tributaries at 29 sampling sites were analysed for a total of 25 parameters, including nutrients, major ions, major elements and traces of heavy metals. Each sampling site represents a sub catchment characterized by a specific composition of 8 land-use categories. Cluster analysis has been applied to divide the sub catchments into five land-use classes. When all measured parameters were taken into account, this statistical method resulted in six groups of sampling sites that are similar in their chemical water composition and that, at the same time, reflects the land use, regardless of sub-catchment size. Water quality was particularly affected by the portions of settlement areas and arable land. Sub catchments which were mainly forested (above 70%) show the smallest level of concentration for all monitored parameters (except Cd, Mn, SO4). Densely populated areas reduce water quality despite high proportions of forest. (C) 2016 Elsevier B.V. All rights reserved.