The wide valleys along lowland sandy-clayey rivers are the land areas preferred for agriculture and human settlement. River courses have been straightened, deepened and dammed for the purpose of drainage. The Aller, Ems and Spree rivers were transformed into shipping avenues. Nearly all courses have also been dyked, which has resulted in the loss of flood plain areas and their connection to the river. The alluvial woods originally present have often disappeared or been reduced to a narrow copse alongside the river. Nutrients and pesticides are washed unhindered from fields into the rivers. As a result, many stretches of lowland sandy-clayey rivers do not at present achieve the “good” ecological quality status formulated as a goal in the EC Water Framework Directive. There are 21 per cent of these courses currently rated as “moderate”, 55 per cent are rated as “poor”, and another 22 per cent even rate as “bad”.
Thomas Holzmann, Vice President of the Federal Environment Agency (UBA), says, “Many lowland rivers need more space on which natural habitats can form and grow. Weirs, sluices and hydroelectric plants can become more uninterrupted through fish ladders and other passages. This will help migratory fish such as the salmon, eel and barbel.“ The input of nutrients and pesticides from agriculture, especially into lowland sandy-clayey rivers, must be reduced. Preservation of water stretches that are in good condition is also important.
About 5,130 kilometres of Germany’s 127,000-km watercourse length are lowland sandy-clayey rivers. Water bodies of this type are typical of the northern German lowlands formed during the last ice age. In sandy areas they flow in shallow hollows or wide riverbeds which form cut banks and slip-off slopes. When they flow through areas with a higher proportion of alluvial loam, these slopes are steep and boxy, which would be ideal for the kingfisher, spined loach, water-starworts, banded demoiselle and river mussels if the rivers were still in a near-natural state.
