Records of Precipitation, Aquifer Head, and Ground-Water Recharge to the Edwards and Associated Limestones, San Antonio Area, Texas, 1969

Author Rettman P (US Geological Survey)
Year 1970
Description Annual report for 1969 on precipitation, aquifer levels, and recharge to the Edwards Aquifer issued by the Edwards Underground Water District
Report Number Bulletin 24
Publisher Edwards Underground Water District
Location Edwards Aquifer Balcones Fault Zone San Antonio Segment
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Records of precipitation, water levels, and estimates of recharge to the Edwards and associated limestones in the San Antonio area during 1969 are summarized in this report. The compilation of these basic records is part of a continuing hydrologic investigation by the U. S. Geological Survey in cooperation with the Edwards Underground Water District and the Texas Water Development Board. Previous reports are given in the list of references.

The annual precipitation at selected stations throughout the San Antonio area for 1969 and the annual average for each of these stations are shown in table 1. Rainfall was above average throughout the recharge area during 1969.

The recorded high and low water levels in five selected key wells during 1969 are shown in table 2. During the year, the water levels fluctuated just below the record high. The record highs and lows are also given in table 2. Ground-water storage in the Edwards limestone was above average during 1969.

Recharge to the Edwards and associated limestones is chiefly from streams that lose most of their base blow and a part of their flood flow as they cross the Balcones Fault Zone on the outcrop of the aquifer. The recharge is estimated from discharge records at gaging stations located above and below the infiltration areas on most of the streams. The monthly mean discharge at the gaging stations for October-December 1969 is given in table 3. Streamflow records for JanuarySeptember 1969 will be published by the U.S. Geological Survey in late 1970.

The recharge in each basin of the San Antonio area for 1969 and the average annual recharge for the period 1934-68 are given in table 4. The basic methods employed by Petitt and George (1956) and by Garza (1962) were used for estimating the 1969 recharge.

Springflow from the Edwards Plateau was the main source of recharge during the first nine months of 1969, while floods during the last three months furnished the main source of recharge. The total recharge was about 10 percent above the average annual (see table 4).