Graduation Year

2009

Document Type

Thesis

Degree

M.S.

Degree Granting Department

Geography

Major Professor

Philip Reeder, Ph.D.

Keywords

Seasonal kendall, Nonparametric, Land use, Tampa, Florida, Geographic information systems

Abstract

Water quality data and land use information were analyzed within the Alafia River watershed in Florida to determine spatial and temporal trends in these variables over a 16 year time period from 1991-2006. Monthly water quality data (for dissolved oxygen, turbidity, fecal coliform, total phosphorus, and total nitrogen) were statistically analyzed using the modified seasonal Kendall nonparametric test for trends that accounts for serial correlation. The statistical trend analysis was conducted for the entire study period, but monthly, seasonal, and land use trends were also examined. Land use information was examined using Geographic Information Systems to determine the percent change in land use proportion from 1990 to 1999, 1999 to 2006, and 1990 to 2006. The proportions of each land use and their percent change were then related to the trends in water quality.

The results of this analysis showed that water quality for the parameters turbidity and total phosphorus have been shown to be improving with statistically significant decreasing trends for turbidity at stations 74, 111, 116, and 139 and for total phosphorus at stations 74, 114, and 115. A statistically significant decreasing trend in dissolved oxygen was determined for stations 116 and an increasing trend in total nitrogen for stations 114, 115, and 151 implying water quality for these parameters is degrading. Other noted trends were high fecal coliform and total nitrogen at station 111, which has higher proportions of agricultural land use and an increasing proportion of urban and built-up land use. Also, low dissolved oxygen was noted at station 74. The proportions of land use for the entire study area have changed from predominantly wetlands to now urban and built-up land use.

While agricultural, rangeland, and wetlands land use have shown a reduction in the proportion of coverage in the contributing zone of almost every station, urban and built-up land use has increased in proportion at every station.

Share

COinS