Statistical summaries of surface-water hydrologic data collected in the Suwannee River Water Management District, Florida, 1906-93

Abstract

Since 1906, hydrologic data have been collected systematically on streams and lakes in the Suwannee River Water Management District (SRWMD) by the U.S. Geological Survey (USGS), the SRWMD, and other agencies. Records of stream discharge and stream and lake stage in the SRWMD (fig. 1), collected largely in cooperation with the SRWMD since 1975, have been published for many years in the USGS annual report series "Water Resources Data for Florida." Streamflow and stream and lake elevation statistics are given in this report for sites shown in figure 1. All 27 daily streamflow stations shown are (or were) operated by the USGS in cooperation with the SRWMD; all 18 lake stage stations shown are now (1994) operated by the SRWMD, but were operated until the late 1970’s by the USGS in cooperation with the SRWMD. All unregulated stream stations which have three or more years of continuous record are included in this report. All unregulated lake stations having at least three years of intermittent lake elevation readings are also included. There are many other sites in the SRWMD for which shorter records or miscellaneous measurements are available but are not included because statistical summaries for such stations require interpretive analysis beyond the scope of this report. Basic hydrologic data have long been recognized as fundamental to the analysis of magnitude and frequency of floods, availability of water supplies, potential for reservoir storage, and permitting of waste discharges. Also, in recent times, scientists and water managers have become more aware of the complex relations between flows and water levels and the terrestrial and aquatic plant and animal life in wetland ecosystems. In 1994, the SRWMD and the USGS began a long-term program of cooperative studies designed to better understand minimum and maximum flow and water levels needed to manage the surface and ground water resources of the District and maintain or improve the various ecosystems therein. Information presented in this report, together with frequency analysis of station data, flow regionalization, studies of the relation of salinity to flow in the lower Suwannee River, definition of ground-water surface-water interactions, surface- and ground-water quality studies, and studies of interaction between surface-water bodies and wetlands, will provide the basis for the SRWMD to establish minimum flow and level requirements for streams and lakes in the SRWMD area. This report is a necessary first step in the longterm program of study because it contains basic stream discharge and stream and lake elevation statistics, most of which are not contained in the annual report "Water Resources Data for Florida." These statistics, most of which were generated using a U.S. Geological Survey computer program, ADAPS, Automatic Data Processing System, characterize normal flows and levels and departures from normal due to floods and droughts or seasonal climatic variations. Specifically, the report presents for the period of record of each stream or lake gaging station, as appropriate: Minimum, maximum, and mean of monthly mean stream elevations and discharges in graphical and tabular form. For streams, annual mean discharge, highest and lowest annual mean discharge, highest and lowest daily mean discharge, minimum annual seven-day mean discharge, instantaneous peak discharge and elevation, instantaneous minimum discharge, and basin yield. Duration of annual daily mean stream elevation and discharge. Duration of daily values are shown in both graphical and tabular form. Duration of daily mean stream elevations and discharge, by months, in tables. Minimum and maximum 1-,3-,7-,14-,30-, 60-, 90-,120-, and 183-consecutive day stream elevations and discharges (with rankings) for each year of record. Mean monthly lake elevations and statistics by month, including number of monthly values, mean, variance, standard deviation, skewness, and coefficient of variation. For convenience, a GLOSSARY of commonly used terms related to the collection and reporting of surface-water elevations and discharge is included before the Introduction section of this report. The authors wish to acknowledge Natalie Rackley, formerly of the U.S. Geological Survey, and T.W. Grubbs, U.S. Geological Survey, for their computer assistance in the compilation of station records, and Jim Tomberlin, U.S. Geological Survey, for the mapping of stream and lake gaging stations.