Heather M. Townsend
The purpose of this project is to determine if there is a correlation between the uses of different soils next to the closed oxbows and the depth in those oxbows due to erosion. An oxbow is a meander of a river which has extreme curvature such that only a small island is left between the new river channel and the old river (Webster 1613). In this project, an oxbow does not form a complete island between the new and old river channels because they are closed off at one end and have access to the river at the other end. These oxbows are closed either because of vegetation or because of never being the main channel and just a side route of the river. The hypothesis states that in closed oxbows, soils on which houses are constructed will be more apt to erode into the oxbows causing them to fill in rather than the soils on which orange groves are planted. This minor experimental comparison will help for better understanding of the oxbows and the areas which surround them so that more in-depth research may be done in the future on the oxbows of the Caloosahatchee River.
This project was selected because of interest in the Caloosahatchee River. Even though two years of study have already been completed on the oxbows, the plans to continue and improve the project are still present because there is much left to learn about these unique ecological environmental systems. The idea of bringing soil into the project came about because of the sediment in the oxbows. This sediment most likely comes from erosion of the surrounding banks of the oxbows and decaying vegetation. By identifying the soil type along the shores of the oxbows, it can be assumed that sediment within the oxbows will possibly contain the same type of soil as on the shore. The other type of sediment that becomes mixed with the eroding soil is decaying vegetative matter.
Closed oxbows within the Hendry County boundaries are being studied in this project. According to the study that was conducted in the fall of 1996, closed oxbows tend to have many differences from the open oxbows as noted by the observations. One difference is that the closed oxbows have quite a bit more vegetation located within them. Another is that there appears to be more decaying sediment within the oxbow causing bubbles that present a fowl sulfur aroma due to hydrogen sulfide rising to the surface of the water. This is supposed to indicate bad conditions for fish and other aquatic life because the decaying sediment uses the needed oxygen for their survival (Townsend 11).
The oxbows that were studied with housing development along their banks varied greatly in soil types, while the oxbows that were studied with orange groves remained the same in soil type. In oxbow #35 which has a nearby house, there are two main types of soil. The first, Udifluvents, consists of spoil material that was piled up along the Caloosahatchee River when the waterway was dredged. Udifluvent soil has very dark gray fine sand. Its surface layer is about 25 inches thick. The underlying material of Udifluvents consists of various mixes of soils such as stratified light gray, light brownish gray, or gray sandy clay; and clay or silty clay; and loamy sand, sandy loam, sandy clay loam, or sandy clay that contains fragments of shell limestone, or possibly both. Udifluvent's composition will vary from place to place and from layer to layer because it is not natural soil. Udifluvent soil could be useful for one cause in one location but in another location it may not be useful for the same purpose. Udifluvent soil is a common type of soil to build homes on and other buildings. The other type of soil near this oxbow is Chobee. Chobee is a fine sandy loam, depressional soil type which is very poorly drained. It is located in marsh, swamp, and depression areas. The soil's surface layer is a black sandy loam about 9 inches thick. Next, the subsoil extends to a depth of about 68 inches. The upper part being gray fine sandy loam and the lower part being light gray sandy clay loam. Chobee also has a high water table which leads to slow drainage.
Oxbow # 27 also has a house along its banks. Riviera is the type of soil that surrounds the oxbow. It is a fine sand which is poorly drained within sloughs and on broad flatwoods. The surface layer of Riviera is very dark gray fine sand about 4 inches thick. Reaching to a depth of about 26 inches, is the subsurface layer which contains fine gray sand in the upper part and fine light gray sand in the lower part. At about 32 inches deep, the subsoil consists of gray sandy loam with vertical intrusions of light gray sand. Gray sandy clay loam is then located at about 50 inches. Next, at a depth of about 70 inches gray sandy loam is found. Finally, the substratum is located at a depth of 80 inches or more and contains gray sandy loam in which a few calcium carbonate fragments can be found. Even though in most cases Riviera soil takes an extremely long time to drain, this type of soil if found near the Caloosahatchee River is moderately well drained. Under natural conditions this soil generally hosts natural vegetation, but if the water table in the area is controlled other plants will survive. This type of soil is bad for development, but due to technology this house was built on Riviera soil.
Wabasso sand is located around Oxbow # 23 which has a house near its shores. It is a poorly drained soil that is located on flatwoods. Wabasso's surface layer is dark gray sand about 6 inches thick. Its subsurface layer extends to a depth of about 25 inches thick and is light gray sand. The subsoil's upper layer is about 30 inches deep containing black sand coated with organic matter. The lower layer is approximately 58 inches deep containing sandy clay loam which is dark grayish brown and also gray sand. The substratum is at a depth of 80 inches and is grayish brown loamy sand. If located near the Caloosahatchee River, Wabasso soil is better drained than other areas with Wabasso soil.
All of the oxbows that have citrus groves surrounding them have Tuscawilla soil along their banks. The three oxbows with Tuscawilla soil are # 18, 21, and 28. Tuscawilla is fine sand located on nearly level, poorly drained soil, and is usually on low lying ridges and hammocks that are between sloughs and depressions. The surface layer is 4 inches thick with dark gray fine sand. Gray fine sand is located at a depth of about 8 inches within the subsurface layer. At a depth of about 56 inches, the upper part of the subsoil is dark grayish brown sandy loam, the next part contains light gray, calcareous fine sandy loam, and in the lower part there is light gray, calcareous fine sandy loam. The substratum is white, calcareous loamy fine sand about 80 or more inches thick. At locations near the Caloosahatchee River Tuscawilla soil is not as wet as it normally is, allowing it with some drainage control, to be quite adequate for citrus tree growth. Tuscawilla soil produces approximately 425 boxes of oranges per acre.
The oxbows of the Caloosahatchee River are similar to wetlands and in some cases are considered to be wetlands. Wetlands are vital to the ecosystems of Florida because they filter pollutants from the water, reduce flood damage, and recharge aquifers for human consumption. Either covered by water for part of the growing season or all year-round, the wetlands are home to much wild and aquatic life. Wetlands are developed along flood-plains, oxbows, and backwater reaches of rivers and streams. They are prime agricultural land which explains why the citrus groves have been planted along the banks of the old Caloosahatchee River.
The oxbows of the Caloosahatchee have brought many different people to its shores. One thing that has brought people is the rich soils that were once seasonally flooded by the river. These soils were perfect for the citrus trees that presently surround some of the oxbows. The homes were built along the banks of the oxbows because of their natural esthetic beauty.
In conclusion, there is not a correlation, according to the graph, between the use of different soils next to the closed oxbows and the depth in those oxbows due to erosion. The hypothesis was not supported by the data. In order to get better results, soil maps of Lee County are needed so that the comparison may include the closed oxbows within Lee County boundaries.
|
Gale, P.M., and K. R. Reddy. Wetland Processes and Water Quality: A Symposium Overview. [United States]: n.p., n.d.
Soil Science Department; and Florida Department of Agriculture and Consumer Services, and University of Florida, Institute of Food and Agricultural Sciences. Soil Survey of Hendry County, Florida. Florida: United States Department of Agriculture Soil Conservation Service, 1990.
South Florida Management District. Draft Report-8758 Caloosahatchee Oxbows: Environmental. West Palm Beach, FL: GPO, 1979.
Townsend, Heather. Long-Term Effects of the Accumulation of Sedimentation in the Caloosahatchee River Oxbows: A Second Look. Florida: 1996.
Webster's Third New International Dictionary. Massachusetts: Merriam-Webster Inc., 1986.
Working With Wetlands. Washington, D.C.: United States Department of Agriculture, 1994.
This page has been accessed
times since
May 29, 1997.
Copyright© 1997 by Heather M. Townsend