VAN HORN, WAYLEN – Analysis of Historical Streamflow Trends of the Santa Fe River, Florida, 1932–2012
Jessy Van Horn, James Richardson, Peter Waylen
Article first published online: Fall 2015 Southeastern Geographer
DOI: 10.1353/sgo.2015.0022
ABSTRACT: Annual mean, maxima, minima and flow duration curves are examined on the unregulated, rural Santa Fe drainage basin in north Florida, 1932–2012. Irrigation within the study area has more than doubled since the 1970s, increasing from about 3,400 hectares to about 7,300 hectares of irrigated land. This influenced a 22 percent decrease in minima and mean flows within the basin. Estimates of annual basin precipitation are made to determine whether the changes are driven by shifts in climate or regional sources of interannual variability. Various statistical tests objectively detect trends, breaks in the time series and significant changes in hydroclimatic characteristics. Low and intermediate flows exhibit marked declines after the break, and are reflected in the annual double mass and flow duration curves, yet changes are almost undetectable in precipitation. The absence of upstream flow regulation and major urban development, and strength of the signals at intermediate and low flows, suggest that the observed flow reductions result from the increased pumping of groundwater for irrigation in the mid-1970s.
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