PULSES - The Importance of Pulsed Physical Events for Watershed Sustainability in Coastal LouisianaEPA Grant Number: R828009
Title: PULSES - The Importance of Pulsed Physical Events for Watershed Sustainability in Coastal Louisiana
Investigators: Day, John , Cable, Jaye , Fry, Brian , Justic, Dubravko , Kemp, Paul , Reyes, Enrique , Templet, Paul , Twilley, Robert
Institution: Louisiana State University - Baton Rouge , University of Southwestern Louisiana
EPA Project Officer: Hiscock, Michael
Project Period: February 28, 2000 through February 27, 2003 (Extended to August 27, 2004)
Project Amount: $899,995
RFA: Water and Watersheds (1999) RFA Text | Recipients Lists
Research Category: Water and Watersheds , Water
Riverine inputs to floodplains, marshes and coastal wetlands are important to long-term ecological productivity and development of watershed resources. In many cases, including much of the Mississippi River drainage basin and delta, levees and dams constructed during the past 100 years have effectively isolated rivers from their natural connections to adjacent floodplain and deltaic wetlands. To help revitalize these productive systems, ecological restoration of historical river-floodplain connections is being attempted. This proposal focuses on evaluating effects of river inputs in one such coastal watershed, the Caernarvon watershed, just south of New Orleans, where river inputs have been ongoing since the 1991 opening of a gated river diversion structure, but have received little scientific attention and study.
Physical science objectives are to evaluate marsh accretionary responses to two different levels of river inputs or diversions, a low input rate (lx = 14m/s) and a high input rate (8x = I 12m3/s). The diversions will be experimentally conducted in two-week episodes as part of the normal operating schedule of the Caernarvon structure, controlled by the Louisiana Department of Natural Resources. In addition to the experimental diversions which will each be replicated four times over the two year field period, historical studies will evaluate effects of a great 1927 flood event at this site (ca. 650x river input) when levees were dynamited for flood relief.
Ecological science objectives air to evaluate marsh plant growth responses to river inputs that bring both sediments and relatively high levels of fertilizing nutrients. Nitrogen nutrient removal via denitrification and burial in wetland soils will be tested in response to soil flooding driven by tropical storms and normal tides as well as by the experimental river diversion inputs. Phytoplankton production and possible eutrophication will be monitored as part of the ecological work, and stable isotope studies will assay effects of river inputs on bass, shrimp and oysters that are the basis of important recreational and commercial fisheries of this area.
Social science objectives aim at providing an interface between the natural and human systems of the region, attempting to place human decision-making in the context of sustainable ecological development for this coastal watershed. Three types of modeling efforts will be employed to make linkages between the human and natural systems more, understandable: landscape simulation modeling, cost/benefit economic analysis, and multicriteria analysis.
Our approach is to mount a coordinated, multi-investigator field program to meet physical and ecological science objectives, with each scientific component based on off-the-shelf technology. The emphasis is on evaluating a combination of experimental treatments (high and low input diversions) as well as taking advantage of storms and tides to document effects of physical pulsing on the overall ecosystem dynamics of this area. Human reactions to natural pulsing (flooding) are usually negative, and the various modeling interfaces we propose will help explore, minimizing negative effects while maximizing positive effects of natural flood events.
The principal benefits of this holistic watershed project are: 1) an improved understanding of marsh accretion important for the sustenance of the coastal platform; 2) tests of eutrophication effects under different marsh flooding scenarios; 3) tests of the connectivity between fisheries and riverine inputs; and finally 4) an evolving educational process involving scientists, managers, stakeholders and schoolchildren in trying to best implement river-floodplain restoration for sustainable maintenance of a wealth-generating coastal zone.