Assessment of the Oxbow Morphology of the Caloosahatchee River and its Evolution Over Time: A Case Study in South Florida

• Main Author: Delhomme, Chloe
• Format: Others
• Published: Scholar Commons 2012
• Subjects: Abandoned Channels; Baseline Data; Channelization; Cross-Sectional Survey; River Morphology; River Restoration; American Studies; Arts and Humanities; Environmental Sciences; Geomorphology; Water Resource Management
• Online Access: http://scholarcommons.usf.edu/etd/4027; http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=5223&context=etd

The Caloosahatchee River, located in Southern Florida, was originally a meandering and relatively shallow river. During the 1920s, the Caloosahatchee River was channelized and became the C-43 canal. The channelization has significantly impacted the river ecosystem, particularly the oxbows. The oxbows are the U-shaped water bodies on each side of the river channel, which are the remnant bends of the original river. To understand how anthropogenic influence affects hydrologic systems, the proposed case study was designed to assess the geomorphic changes of the oxbows of the Caloosahatchee River, Florida. Understanding and documenting the evolution of river morphology is becoming increasingly important today with increasing river degradation due to anthropogenic activities. In fact, such monitoring will provide critical information regarding river conditions to support future management plans and restoration efforts. Monitoring is a key element of successful management. This study provided a baseline for future monitoring by assessing the current morphologic conditions of the thirty-seven oxbows of the Caloosahatchee River, coupled with GPS data. Bathymetric surveys were used to assess the morphology of the oxbows. The study also presented trends in the evolution of oxbow morphology by comparing the data collected from the survey in 2011 with a cross-sectional survey collected by the South Florida Water Management District in 1978. The study revealed that 21 of 37 oxbows are still open; however, 16 are already partially filled, either at one of the ends or somewhere in the interior. In both 1978 and 2011, oxbows in Lee County were significantly larger, wider and deeper than in Hendry County. Exterior limb cross-sections were significantly larger, wider and deeper than interior cross-sections in both 1978 and 2011. Finally, an attempt to determine trends in the evolution of the morphology of the oxbows demonstrated that the overall maximum depth is significantly decreasing but only in the interior of the oxbow and that the mean depth is significantly increasing but only in the exterior cross-sections. This analysis also showed that the width is significantly increasing throughout the oxbow. Factors responsible for such differences may include natural geomorphic processes, pattern changes due to channelization, land use and anthropogenic activities.