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Patterns of Short‐Term Sedimentation in a Freshwater Created Marsh
Author(s) -
Harter Sarah K.,
Mitsch William J.
Publication year - 2003
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2003.3250
Subject(s) - sedimentation , sediment , marsh , wetland , hydrology (agriculture) , bioturbation , turbidity , environmental science , geology , turbidite , silt , ecology , geomorphology , oceanography , biology , geotechnical engineering
This study investigated different sedimentation measurement techniques and examined patterns of short‐term sedimentation in two 1‐ha replicate created freshwater marshes in central Ohio, USA. Short‐term (one‐year) sediment accumulation above feldspar, clay, glitter, and sand artificial marker horizons was compared at different water depths and distances from wetland inflow. A sediment budget was also constructed from turbidity and suspended sediment data for comparison with marker horizons. Glitter and sand marker horizons were the most successful for measuring sediment accumulation (81–100% marker recovery), while clay markers were completely unsuccessful. The sedimentation rate for both wetlands averaged 4.9 cm yr −1 (36 kg m −2 yr −1 ), and ranged from 1.82 to 9.23 cm yr −1 (12.4 to 69.7 kg m −2 yr −1 ). Sedimentation rates in deep, open water areas were significantly higher than in shallow, vegetated areas for both wetlands ( t test, p < 0.05). However, observed sedimentation patterns may be attributed more to preferential flow through open water areas than to water depth or presence of vegetation. Contrary to the expected spatial distribution, sedimentation was highly variable within the wetlands, suggesting that bioturbation and turbulence may cause significant resuspension or that high hydrologic loads may distribute sediments throughout the basins. A sediment budget estimated sediment retention of approximately 740 g m −2 yr −1 per wetland (43% removal rate), yet gross sediment accumulation was 36 000 g m −2 yr −1 measured by marker horizons. These results suggest that erosive forces may have influenced sedimentation, but also may indicate problems with the sediment budget calculation methodology.