Concluding event of the NiersCon project: Results on decen-tralized water retention presented

On March 25, 2026, the district of Viersen, together with the Middle Niers Water and Soil Association, presented the results of the NiersCon project on decentralized water retention in the regional ditch system. The FiW was represented at the closing event by Jana Vredenburg, Thurid Roth, and Gregorio Cevoli, who provided scientific support for the project.

The project was funded by the Federal Ministry of Research, Technology, and Space (BMFTR) as part of a funding initiative to adapt to the consequences of climate change. The landscape water balance in the district of Viersen is characterized by numerous drainage ditches that serve to divert stormwater during wet periods. However, these ditches are not currently used for water retention during dry periods. The aim of the project was, in accordance with the concept of a “sponge region,” to retain water in the landscape for longer and in a more decentralized manner by controlling the drainage ditches, thereby stabilizing the local water balance for climate change-induced dry periods. Representatives from administration, water management, and research discussed the results and prospects for further implementation.

In the NiersCon project, the project partners investigated how existing ditch systems can be further developed so that water remains in the landscape longer, thereby fostering a forward-looking and climate-adapted water management system. By keeping water in the regional ditch system longer, it will be available for the soil, vegetation, and groundwater, while newly introduced controllable elements simultaneously maintain the drainage function during heavy rainfall.

As part of the project, various measures were tested that can be integrated into existing infrastructure. These include deadwood elements that slow down runoff, controllable weirs for targeted water retention, and modifications to existing retention basins to utilize additional storage capacity. These measures are low-threshold and directly applied within the existing ditch system, and can be implemented with relatively little construction effort. Data from sensors installed at selected locations to measure water levels, soil moisture, and other parameters were digitally transmitted and centrally analyzed. Initial analyses showed that dammed ditches retain water in the system longer, while undammed areas dry out more frequently or have shallower water depths. Additionally, soil moisture near ditches remains higher when dammed. Hydrological models were also used, which indicated increased potential infiltration under controlled damming conditions.

The FiW provided scientific support for the project. This included a GIS-based analysis to identify suitable locations, the evaluation of measurement data from the installed sensors, and studies on the potential for evaporative cooling provided by water bodies. In addition, the FiW developed graphical representations for science communication, which made the functioning of the measures easy to understand.

The results demonstrate that existing ditch systems offer significant potential for water retention. Collectively, multiple small-scale measures can help stabilize the landscape’s water balance. At the same time, effectiveness depends heavily on the specific location. Individual case assessments are therefore required for each measure. Coordination with authorities, maintenance agencies, and landowners is also crucial for implementation. For further implementation, the project partners plan to gradually expand suitable measures and transition them into routine operation. This includes using the project results for further planning, expanding monitoring and management, and clarifying financing and long-term maintenance. The goal is to develop a networked system of measures that stabilizes the water balance and can be flexibly adapted to changing conditions.