This study presents the results of the influence of the specific geological landforms occurring in a lowland river floodplain on the recharge and drainage conditions in an agricultural area. Particular attention has been paid to the presence of the buried erosional channels of flood waters, which may constitute the preferential paths for migration of agricultural contaminants. Moreover, the changes of effective infiltration which affect the hydrogeological regime of the tested area were analyzed. Priority was also given to the use of laboratory techniques in order to determine the parameters influencing the contaminant migration in the soil-water environment for the purpose of hydrogeological modeling. Laboratory tests, based on a column experiment, were performed in a Trautwein apparatus with reference to the constant head procedure, using conservative and reactive markers. The parameters of advection, dispersion, and sorption, obtained in the laboratory experiment were then used as the input data for the hydrodynamic model of groundwater flow and contaminant migration in the research area. Based on the created digital model of groundwater flow, the multi-variant analysis of the effect of specific geological features on the conditions of contaminant transport in a valley was performed. The presented tools and methods contributed to a significant increase in the accuracy of recognizing zones susceptible to water pollution and should be adopted in other valley areas exposed to contamination.

We explored the background of differences in long–term stability between two parts in an undisturbed mire system (Rospuda fen, NE Poland). We re-constructed the Holocene history of the mire and compared it with current vegetation, water level dynamics, water chemistry and nutrient availability in two basins: A, where the mire terrestrialised a deep gyttja–filled lake, and B, where peatland developed directly on fluvial sands. The current vegetation of sedge–moss fens was described in 10 relevés from each basin, groundwater was sampled from piezometers and analysed for major ions, while its relative water level was recorded during three years. N and P content was measured in above ground vascular plant samples collected within the relevés. Fens in basin A were stable in the past, whereas fens in basin B switched between open and wooded or reed–dominated phases. In basin B, where trees are more abundant, we found higher water fluctuations, occurrence of river floods and a higher N:P ratio than in basin A. Our interpretation follows that the subsurface geology of fen basin may govern mire stability by determining its hydrological–buffering capacity, which may affect N:P ratios. Our results suggest that P–limited fens are more vulnerable for changes in water level.

Using ALS LIDAR DEM and OpenStreetMap data we visualise in ArcGIS the geomorphic features of a large, lowland river which flows through the area impacted by urbanisation of a big city – the capital of Poland. We present on one map the main geomorphological surfaces and their exact boundaries: valley edge, terrace front and floodplain juxtaposed with buildings and the main transportation corridors. We identify convex aeolian and fluvial landforms: dunes, levees, sandy lobes including crevasse splays, ridges between swales, sandy bars, islands; and concave erosional landforms: floodplain channels, crevasse channels, oxbow lakes, palaeo-meanders, tributary channels, and chute channels. We draw implications for flood management, geo-archaeology geo-heritage conservation. We search for traces of extreme flood events in the Holocene, also on the higher terraces which the river developed by its deposition in the Pleistocene.