Impact of Land Use and Runoff on Stream Quality

Abstract

Climate changes, intensive agricultural production, and expanding urban areas make the study of runoff and its possible impact on stream quality increasingly important. In this study, we examined large datasets concerning catchment type, stream quality, and invertebrate composition in a comprehensive geographic information system study. The aim was to examine correlations between land use type and quality of the receiving waters to detect possible differences in anthropogenic impacts. The studied area covered 937 km2, and the dataset included 1672 stretches of streams and data from 468 fauna sampling stations. Runoff from agricultural areas more negatively influenced the stream quality than runoff from urban areas. Considering urban catchments, the areas with separate sewer systems generally influenced the stream quality less than catchments with combined sewer systems. In conclusion, the catchment of any specific stream must contain an area with a minimum of 20–30% without agriculture or urban areas to obtain good ecological status; when focusing only on the riparian zone (10 m on each side of the stream), a minimum of 40–55% is needed to create a good ecological status. Therefore, management focus on the entire catchment is important and separate sewers should be preferred rather than combined sewers.

Modeling Water Quality in Watersheds: From Here to the Next Generation

“…For example, there might be hundreds of SSSOs delivering important pollutant loads ( Brombach et al, 2005 ; Masoner et al, 2019 ) to a single river reach. The effects of wet-weather discharges on receiving water bodies are often site specific ( Karlsen et al, 2019 ), with both chronic (often caused by the loads discharged from SSSOs) and acute impacts (often caused by combined sewer overflows resulting in oxygen depletion and/or ammonia toxicity). The latter can also depend on seasonal variations in the river conditions (e.g., oxygen solubility and baseflow), and they can be limited in space ( House et al, 1993 ).…”