Biogeochemical consequences of winter flooding in brook valleys

Abstract

Climatic change has great impacts on stream catchments and their ecology. Expectations are that more extreme climate events will result in undesired flooding in stream catchments. In the Netherlands, former floodplains with a history of agricultural use are put into use again as flooding areas for the purpose of water retention. This study focuses on the effects of winter flooding on various plant site conditions in the soil, such as redox, nutrient, pH, and base status. We compared the effects on groundwater-and rainwater-dominated floodplains. Water chemistry (pH, EC, HCO 3 , SO 4 , Cl, Ca, Mg, Na, K, p CO 2 , NO 3 , NH 4 , and PO 4 ) and soil nutrients (Total N and P, and bio-available P) were monitored for one year, including a 3-4 month period with winter flooding. In both floodplains no direct effect of the flood-water chemistry was detected in the pore water, because the soil pores had become saturated with groundwater or rainwater, respectively, just before flooding, flood-water did not penetrate the soil. We found that the increase in pH and ammonium concentration in the rainwater floodplain were due to changes in redox status, resulting from the completely water-filled state of the soil pores during the flooding event. Furthermore, we noticed an increase in soil nutrient contents and a shift in plant species composition in the rainwater floodplain: the vegetation included more plant species characteristic for N-richness. Finally, we conclude that winter flooding has more drastic effects on biogeochemical conditions and vegetation composition in the atmotrophic conditions characteristic for low-order subcatchments than in lithotrophic conditions in the larger, higher-order subcatchments of the stream basin.

Efficiency of Drainage Practices for Improving Water Quality in Lithuania

“…In the pores of the waterlogged soil, the oxygen content decreases. A reduction in the oxygen content can create anaerobic conditions, leading to denitrification, methanogenesis, and the reduction of manganese, iron, and sulfate, resulting in a lowering of the soil redox potential (Beumer et al, 2007). Changes in the pH and redox reactions change the bio-availability of nutrients in the soil (Violante et al, 2010;Lynch et al, 2014).…”

“…Changes in the pH and redox reactions change the bio-availability of nutrients in the soil (Violante et al, 2010;Lynch et al, 2014). The NH 4 -N and PO 4 -P levels increase when the soil conditions become anaerobic (Beumer et al, 2007;Loeb et al, 2007).…”

The fluctuation of calcium and magnesium concentrations in the floodwater in the Nemunas and Minija lowlands

“…reduction of manganese, iron, and sulphate, resulting in a lowering of the soil redox potential (Beumer et al, 2007). Alteration in pH and redox reactions will change the bioavailability of nutrients in the soil (Lynch et al, 2014).…”

“…Alteration in pH and redox reactions will change the bioavailability of nutrients in the soil (Lynch et al, 2014). pH, ammonium and phosphate levels increase, when the soils become anaerobic (Beumer et al, 2007;Loeb et al, 2007). When pH drops below 4.5, almost all carbonates are dissolved and adsorption to Fe oxide is the dominant mechanism (Lucassen et al, 2002).…”

Relations between vegetation and water level in groundwater dependent terrestrial ecosystems (GWDTEs)

“…Infiltration of nutrient rich surface water e.g. following a flooding event may also result in increased nutrient availability (Beumer et al 2007, Banach et al 2009, Cusell et al 2015.…”