Solar input into the atmosphere provides the basic energy for all life on earth. At the same time its excess may cause problems for certain ecosystems. For river systems riparian shading is essential for the development of an intact, diverse and native biocenosis. The aim of this study is to quantify the solar radiation of different sectors at the Wien River in Vienna and Purkersdorf, Austria. Firstly, the question is discussed on the basis of solar radiation, and the study area is described. Additionally, the change in water temperature for the relevant area is visualised and the vegetation is characterised for chosen sectors. The amount of solar radiation was measured using hemispherical photography in combination with the software HemiView. This method as well as the way of gathering the temperature and mapping the vegetation is explained in detail. Finally, the results are presented and discussed. As expected, distinctive variation concerning the solar radiation impact on different sectors of the Wien River was found. In areas with high and dense riparian vegetation the level of shading is comparable to shade caused by architectural structures. Due to a lack of sufficient data, causal relations between shading and change in water-temperatures could not be analysed in detail.