Professional Paper Sj 2011-Pp1 Evaluation of Discharge Data for Blue Spring, Volusia County, Florida, for the Period 1932-2006.

摘要

St. Johns River Water Management District (SJRWMD) established minimum flows and levels for Blue Spring, Volusia County, Florida, in 2006 as a minimum flow regime (MFR). SJRWMD evaluated available spring discharge data for Blue Spring for the period of March 1932-June 2006, in support of establishment of the MFR. This evaluation included an exploratory data analysis followed by statistical hypothesis-testing based on the Mann-Whitney U-test and the median test. The evaluation of Blue Spring discharge data for the period of record (1932-2006) was based on 658 discharge measurements. Results indicate that the minimum discharge was 63 cubic feet per second (cfs), the maximum was 218 cfs; the median discharge was 159 cfs; and the mean discharge was 157 cfs. Based on LOESS (locally weighted scatterplot smoothing) statistics, the median spring discharge for the manatee season is 5 cfs higher than the median discharge for the period of record. The Mann-Whitney U-test and the median statistical test indicate that there is a statistically significant difference between the two data sets. Based on LOESS statistics, the median spring discharge for the manatee season is 9 cfs higher than the median discharge for the nonmanatee season. The Mann-Whitney U-test and the median statistical test indicate that there is a statistically significant difference between the two data sets. Therefore, discharge from Blue Spring is higher during the manatee season, which extends from November through March, than during non-manatee season of April through October.