What is sustainable water management essentially about?
Koch: In addition to technical measures such as water-saving irrigation systems, sustainable water management relies heavily on agro-ecological measures. Three aspects are of utmost importance: keeping water in the landscape, the importance of vegetation and the role of soil. In the past, people have tried to drain water from the landscape as quickly as possible: Rivers were straightened, swamps and meadows drained, etc. The result is that today we have too few water reserves and natural water reservoirs in the landscape, which becomes a problem during longer dry periods and extreme precipitation. For reasons of climate protection and water balance, some of the "wetlands" should therefore be renaturalised in order to have more water (reserves) in the landscape again.
Vegetation plays a key role in the water cycle. Less bare land in the landscape, less sealed surfaces in cities, more vegetation and more trees mean more evaporation and cooling and thus more of rain formation. This includes all measures of greening agricultural land throughout the year if possible, but also that we bring more trees back into the agricultural landscape. And last but not least, so-called "water harvesting" is also important, for example the construction of rainwater retention basins or infiltration trenches.
Moreover, sustainability begins with the soil, and this is especially true for water! A healthy and fertile soil acts like a sponge and is of enormous importance as a water reservoir, both for flood protection and in dry periods. Therefore, all measures that promote soil fertility, a good soil structure and high biological activity of the soil are of utmost importance, as they improve infiltration, water storage capacity, but also water quality. Here, organic farming with its focus on soil fertility definitely has a system advantage.
Lochmann: Furthermore, sustainable water management should go beyond the individual farm and include the entire watershed. Internationally, there are examples of "water stewardship", i.e. the cooperation of different water users in a catchment area.