WATER RESOURCES OF ORANGE COUNTY 47
the entire basin is estimated to be 10 inches. Average yearly runoff from the western part of the basin is probably less than 4 inches and that from the eastern part 14 inches or more. Curve No. 4 (fig. 15) is the estimated flow-duration curve for Reedy Creek near Vineland. Note that the variability in flow (the steeper the slope of the duration curve the more variable the flow of a stream) is less during the upper 10 per cent of flow than during the middle 80 percent. This is due to the storage effect of lakes and swamps which tends to distribute high flow over a longer period of time. The stream is dry about 10 percent of the time.
Analyses of water collected from Reedy Creek at station 54 at low flows on June 15, 1960 and May 23, 1961, show the water to be very soft and low in mineral content. At almost zero flow on May 23, 1961, the hardness was 11 ppm and the mineral content, based on a conductivity measurement, was estimated to be 24 ppm. The low mineral content in the water indicates Reedy Creek probably does not receive very much ground-water inflow.
Bonnet Creek
Bonnet Creek and its tributary, Cypress Creek, drain 55 square miles of Orange County, east of Reedy Creek basin. The part of the Bonnet Creek basin that is drained by Cypress Creek differs hydrologically from the rest of the basin.
Land surface altitude in Bonnet Creek basin ranges from abut 75 feet at the county line to 195 feet near Windermere. Altitudes in the western part of the basin, the part excluding Cypress Creek basin, range from about 75 to 130 feet. This area is mostly flat and swampy but it contains several lakes of moderate size and islands of low relief. Figure 19 shows profiles of stream beds in Bonnet Creek basin.
The minimum flow observed at Bonnet Creek near Vineland (station 48), 1 mile south of the county line, was 0.4 cfs in May 1961 and the maximum flow was 1,180 cfs at the peak of the flood in September 1960.
The average flow at station 48 is estimated to be 33 cfs or 0.60 cfs per sq. mi. Average yearly flow from the entire basin is estimated at 8.1 inches. Prorating this yield between the 30 square miles of Cypress Creek basin, for which the gaged yield is 4.4 inches, and the remaining 25 square miles of the western part of the basin gives an average yield of 12.6 inches from the western part. Curve 6 (figure 15) is the estimated duration curve for