2nd UF Water Institute Symposium Abstract

Submitter's Name Yogesh Khare
Session Name Poster Session: Hydrologic, Biogeochemical and Ecological Processes 1
Category Hydrologic, biogeochemical and ecological processes
Poster Number 219
Author(s) Yogesh Khare,  Graduate Student, Civil & Coastal Engineering Department, University of Florida
  Christopher Martinez,  Assistant Professor, Agricultural & Biological Engineering Department, University of Florida
  Detection of trends in stream flow, base flow and nutrient concentrations in the Alafia River
  Determination of long term and seasonal trends is important in order to study the impact of land use and climate change on discharge variables and nutrient concentrations. The objective of this study was to determine yearly and seasonal trends in discharge variables and several water quality parameters in the Alafia River watershed. The data was obtained from U. S. Geological Survey discharge gage stations and Environmental Protection Commission of Hillsborough County (EPCHC) water quality gage stations. Gages were selected based on length of time series and were grouped into 3 pairs based on their locations. Station 1 (North Prong Alafia River near Keysville) and station 2 (South Prong Alafia River) are on the upstream side of station 3 which is on main Alafia River. The study period ranged over the years 1974-2007. Non-parametric trend detection techniques namely Mann-Kendall test and Seasonal Kendall test were used for analysis. In all, three discharge variables (stream flow, base flow and percentage base flow) and four water quality parameters (Total Phosphorus, Total Kjeldahl Nitrogen, Ammonium and Nitrite/Nitrate Nitrogen concentrations) were tested. Yearly as well as seasonal stream flow, base flow and percentage base flow did not show any significant trend at any location. Seasonal Total Phosphorus (TP) and Ammonium concentrations decreased considerably at all stations, while Nitrate/Nitrites concentrations decreased at two of the three locations, station 1&3. On the other hand, Total Kjeldahl Nitrogen (TKN) concentration increased at station 2&3. Water quality parameter trends (except TKN trends) at North Prong Alafia River and the main Alafia River were similar. Impact of land use and climate change on discharge variables is minimal. Amongst the water quality parameters Total Kjeldahl Nitrogen showed adverse trends and hence needs a due consideration.