What we can learn from a wetland water balance? Narew National Park case study

Analyses carried out in this paper aimed to provide an integrated, dynamic, yet simple water balance model for riparian wetland areas with insufficient observation data. The proposed approach was based on a combination of a conceptual model of wetland water balance with an integrated river basin model SWAT (Soil and Water Assessment Tool). It allowed determining the water balance components of the protected part of the Upper Narew River valley. Scenario analyses were conducted with the aim of evaluating the effect of changes in external and internal factors on the water storage within the NNP wetlands, with a particular emphasis on the issue of soil desiccation. The model calibration was based on comparing simulated water storage within the wetland with the mean groundwater depths for the period 2000–2004. The reference conditions were defined by the “Baseline” scenario (water balance simulations for the period 1990–2009), whereas future conditions were represented by three scenarios: “Climate” (climatic changes according to two GCMs driven by SRES A2 emission scenarios), “Reservoir” (changes in operation of Siemianówka reservoir situated upstream of the study area) and “Succession” (changes in vegetation cover of the NNP). The results allowed identifying possible factors contributing to degradation of hydrogenic habitats. The conclusion from this study is that the largest impact on the water storage within the NNP wetland, and thus on water conditions for hydrogenic habitats can be expected under projected climate change, whereas scenarios of change in reservoir operation and vegetation succession have a rather moderate impact.