Relationship Between Watershed Land-Cover/Land-Use Change and Water Turbidity Status of Tampa Bay Major Tributaries, Florida, USA.

The extent and change of land cover/land use (LCLU) across the Tampa Bay watershed, Florida, was characterized for the time period between 1996 and 2006. Likewise, the water turbidity trend was determined at a site near the Bay for each of four major tributaries to Tampa Bay (Hillsborough River, the Alafia River, the Little Manatee River, and the Manatee River). This study identifies consistent changes in LCLU across the Tampa Bay watershed and a decrease in water turbidity. LCLU change analysis as a percent of the total Tampa Bay watershed revealed an increase of 2.6% in developed area followed by a 0.9% in bare land and a 0.6% in water cover. A decrease of 1.8% of the total Tampa Bay watershed was found in agriculture, followed in order by 1.1% in wetland and 1.4% in scrub/shrub. Other land classes changed less than 0.2% of the total watershed. A linear mixed model (SAS procedure PROC MIXED) revealed an overall decreasing trend in water turbidity ( p = 0.003, slope estimate = −0.02) across the four major Tampa Bay tributaries considered. This study suggests that development (urbanization) could be associated with decreasing water turbidity in Tampa Bay. Finally, although these results may help explain similar effects on other water bodies with similar conditions of adjacent urbanization and low slope, more analysis are needed considering a larger number of watersheds with similar scales and longer time period in order to confirm that the findings of this study are generally evident. [ABSTRACT FROM AUTHOR]