Landscape-scale ecohydrological mapping demonstrating how flood inundation water quality types relate to floodplain vegetation communities

Abstract

Landscape scale ecohydrological mapping is commonly restrained to one-dimensional ecohydrological transect studies or two-dimensional vegetation distributions lacking adequate spatial coverage of explanatory hydrological data. The objective of this paper is to construct a two-dimensional (semi 3-D) landscape-scale ecohydrological map based on vegetation distribution maps and detailed spatial, multi-year, floodplain inundation water quality data. The dataset comes from the near-natural Biebrza floodplain mire in Poland encompassing 658 inundation water quality analyses over the period 2002-2012, covering 17 different vegetation communities of freshwater marshes and rich-fens. The data represent the main hydrological gradients from valley edge to river encompassing groundwater seepage, local stagnant precipitation influences and river flooding and drainage. We used chi square Haberman residuals analysis to correlate communities to inundation water quality types, resembling river water and three different types of groundwater. Out of 17 communities, 6 showed a preference for river water, 3 showed a preference for clean groundwater, 4 for diluted groundwater, and 1 for polluted groudwater. For 3 communities no significant preference was found. Spatial patterns in vegetation and attributed water quality preference can be linked to three dominant hydrological processes at the landscape-scale, i.e. discharge of clean and polluted groundwater near the valley edges, dilution of exfiltrated groundwater with local snowmelt and precipitation water, and flooding with river water along the river. The ecohydrological relations are depicted in two-dimensional maps and a semi 3-dimensional diagram with typical cross-sections.