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ASSESSING CUMULATIVE IMPACTS OF LEVEES AND DAMS ON FLOODPLAIN PONDS: A NEUTRAL‐TERRAIN MODEL APPROACH
Author(s) -
Gergel Sarah E.
Publication year - 2002
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/1051-0761(2002)012[1740:aciola]2.0.co;2
Subject(s) - levee , floodplain , flood myth , environmental science , hydrology (agriculture) , wetland , terrain , flood stage , watershed , 100 year flood , ecology , geography , geology , geotechnical engineering , archaeology , machine learning , computer science , biology
Nearly all large rivers and their floodplains in the Northern Hemisphere are subject to multiple disturbances such as levees, impoundments, channelization, dams, and changes in land use. Isolating the relative impact of different disturbances is difficult when the combined effects are nonadditive. I developed a “neutral‐terrain model” to examine the cumulative impacts of levees and dams on the hydroperiod of ponds and wetlands that form throughout floodplains after flood events. Using simulated floods of different magnitude, I address two major questions: (1) What is the relative influence of levees vs. dams on the duration and abundance of temporary ponds and wetlands? (2) Are the cumulative effects of levees and dams additive, synergistic, or antagonistic? Levees decreased the area occupied by temporary ponds (as compared to the natural scenario), until the levee was breached by large‐magnitude events. When the levee was breached, no differences were found between the natural‐ and levee‐floodplain scenarios. A simulated upstream dam decreased, increased, or had no effect on the area occupied by temporary ponds, depending on flood magnitude. Synergistic interactions between levees and dams were apparent for larger floods, where the reduction in flood stage caused by an upstream dam prevented levee breaching. Lastly, I introduce a qualitative framework for understanding the impacts of levees and dams on the duration of floodplain ponds. I also discuss the applications of this new three‐dimensional simulation modeling technique, neutral‐terrain modeling, as a tool for addressing spatial aspects of watershed and floodplain questions.