The Upper Stör catchment is located in the middle of Schleswig-Holstein, Northern Germany, with a river length of 25 km and a drainage area of 468 km² (Figure 1(a)). As part of the Northern Germany lowland area, the altitude of this area falls from 90 and 60 m in the western and eastern parts, respectively, to 2 m a.s.l. at the outlet. In most of the catchment the gradients are smaller than 1 °, except the south western part, which has gradients of more than 3 ° (LAV S-H 1995). Due to the high latitude and low lying terrain, shallow groundwater tables and older glacial and glaciofluvial sediments cover the basin, and there are criss-cross ditches, drainage pipes and canalization. In addition, this area is controlled by a temperate maritime climate, with an annual precipitation of 831 mm/year and a mean annual temperature of 8.3 °C (Müller-Wohlfeil et al. 2000; Schmalz et al. 2008; Schmalz & Fohrer 2009). The combination of terrain and climate has promoted agricultural activity, and has resulted in a land use pattern dominated by arable land (48.1%), pasture (29.5%) and forest (9.1%). Ten river sections were selected according to the following criteria: a smooth and regular inner river wall; no flood regulation; no turbulence caused by large obstacles, dams or waterfalls. The attributes of the ten river sections are shown in Table 1.