Samenwerking Nederland-Polen op gebied van water en natuur in de Biebrze-vallei

Om de verdroging in delen van de Biebrza-vallei (moerasgebied in het noordoosten van Polen) tegen te gaan, is met steun van de Nederlandse overheid een langjarige samenwerking op touw gezet tussen onderzoeksinstituten en universiteiten in Nederland en Polen. Het onderzoek moest de effecten van herstelmaatregelen in kaart kunnen brengen. Met behulp van hydrologische modellen zijn maatregelen, zoals het afdammen van kanalen of dempen van slootjes, geëvalueer

Ecohydrological system analysis of the Lower Biebrza basin

The Biebrza National Park, situated in north-east Poland, is a unique environment of wetland with very well developed zones of peat ecosystems. At present the wetlands are threatened by numerous factors associated with human activity (drainage, ceasing of mowing) as well as natural succession. Understanding the hydrology gives a proper basis for nature management in the area. The physically-based groundwater and surface water model SIMGRO was used to gain insight in the regional ground-water flow. Using these results, flow lines were calculated, giving information on the sources of water flows to the different ecosystem types in the river basin. Major sources of water are from the glacial plateau, the river water system as water flowing to the Biebrza river and a local system in the flood plains of the Biebrza valley. All this information is important for preserving suitable hydrological conditions for the various wetland types

Modelling Peatland Hydrology: Three cases from Northern Europe

Many of the peatlands that used to extend over large parts of Northern Europe have been reclaimed for agriculture. Human influence continues to have a major impact on the hydrology of those that remain, affecting river flow and groundwater levels. In order to understand this hydrology it is necessary to analyze and assess the groundwater and surface water system as a whole. The SIMGRO model was developed for such situations: it simulates groundwater flow in the saturated and unsaturated zones and also surface water flow. Being physically-based, it is suitable for application to situations with changing hydrological conditions and for practical aspects of water management in peatlands. This paper describes the application of the model to different hydrological situations in the Netherlands, Poland and Lithuania. The 3 cases deal with aspects of flooding, natural flow regime and flood storage in relation to suitable conditions for agriculture and nature. The calibration of the model for the cases was limited, but the simulation results show that the estimates of the discharges and groundwater levels were satisfactory, demonstrating that the model is an adequate tool for simulating the hydrological system, and has the potential to assess the impact of different measures. The Dutch case demonstrates that lowland basins where the groundwater has been lowered by extensive land drainage can be restored by restricting the inflow of surface water from the upper parts of the basin: peak flows are significantly reduced. For the Polish case, the damming of ditches in the valley of the Biebrza River could significantly improve the water regime in the peatlands of this floodplain. For the Lithuanian case, the flow regime for the Dovine River could be made more natural if sluice gates were replaced by overflow spill weirs. Understanding the hydrological system is crucial for sustainable land development and effective soil and nature conservation. The different measures simulated in the 3 cases illustrate SIMGRO’s potential to simulate hydrological measures