2006 Greater Everglades Ecosystem Restoration Conference

Arthur R. Marshall Loxahatchee National Wildlife Refuge Water Budget Model

Ehab A. Meselhe 1, Jeanne C. Arceneaux 1, Alonso G. Griborio 1, Emad Habib 1 and Michael G. Waldon 2

1 Center for Louisiana Inland Water Studies, University of Louisiana at Lafayette, Lafayette, LA, USA
2 Department of Interior Everglades Program Team – U.S. Fish and Wildlife Services, Boynton Beach, FL, USA

The Arthur R. Marshall Loxahatchee National Wildlife Refuge also known as Water Conservation Area 1 (WCA-1) is 143,238 acres (58,000 ha) and is located approximately seven miles west of Boynton Beach, FL where it is all that remains of the northern Everglades in Palm Beach County, FL. According to the U.S. Fish and Wildlife Services (USFWS) there have been changes in the water quantity, timing, and quality that are introducing negative impacts to the Loxahatchee Refuge’s ecosystem. Therefore it has become a top priority for the Loxahatchee Refuge to make certain that an appropriate water regulation schedule that will produce maximum benefits for flood control, water supply, fish and wildlife, and also to help better understand and minimize the impacts of the excessive nutrients’ loading. This paper will present the development of a water budget model for the Loxahatchee Refuge which will provide a useful tool in support of Refuge water management decisions. The water budget model was developed as a double-box model that predicts canal and marsh stages from observed inflows, outflows, precipitation, evapotranspiration, and seepage. This model evolved from an earlier model based on the water budget and constituent mass model developed by Dr. William W. Walker, Jr. Significant modifications were introduced in order to fit the needs of using the model as a management and analysis tool. The major modifications to Walker’s model include: (1) prediction of canal and marsh stages instead of outflow, (2) inclusion of seepage in the balance, (3) use of multiple stations in the precipitation analysis, (4) introduction of reduction factors in the evapotranspiration calculations based on marsh conditions, and (5) consideration of the U.S. Army Corps of Engineers regulation schedule where the release of water is modeled as a function of position within the regulation schedule zones. The water budget model was calibrated for the 5-year period of record between January 1, 1995 and December 31, 1999, and validated for the period of record between January 1, 2000 and December 31, 2004. Statistical analyses were completed and demonstrate the applicability of this water budget model to predict the temporal variation of water levels in both the marsh and the Refuge rim canal. The Loxahatchee Refuge water budget model is currently being evaluated to determine any further improvements which could be made to better help the Refuge in making water management decisions. Also additional efforts are being devoted to model the mass balance of water quality constituents as chloride, total phosphorus, and other nutrients which impact the ecology of the Loxahatchee Refuge.

Contact Information: Jeanne C. Arceneaux, Center for Louisiana Inland Water Studies, University of Louisiana at Lafayette, P.O. Box 42347, Lafayette, LA 70504-2347 USA, Phone: 337-501-4344, Fax: 337-482-0698, Email: jca1666@louisiana.edu