Stream Recharge Water Balance for the Barton Springs Segment of the Edwards Aquifer

Abstract

Abstract:Channel water balance analysis based on streamflow loss coupled with traced groundwater basins allow refinement of upland autogenic recharge values comparable to those derived from more precise site-scaled measurements. Based on total discharge and calculated flow loss in major stream channels, the channel contributions to recharge on the Barton Springs Segment of the Edwards (Balcones Fault Zone) Aquifer are: Onion Creek (32.6%), Barton Creek (less than 10.5%), Slaughter Creek (7.2%), Bear Creek (6.2%), Blanco River (6%), Little Bear Creek (3.4%), and Williamson Creek (1%). Major stream channels contributed from 56% to 67% of total groundwater recharge to the groundwater system, 17% of which was stream autogenic recharge, while upland autogenic recharge and other smaller sources contributed the remaining 33% to 44%. As a percent of precipitation over the Edwards Aquifer outcrop source area, autogenic recharge (upland and tributary recharge in the major stream channels) was 22% to 28%, compared with a recharge value of 28% of precipitation from climate tower water balances in Central Texas. Prior to delineation of groundwater basins using injected tracers, older channel water balance studies determined that upland autogenic recharge was only 15% of the total groundwater recharge (about 1% of precipitation). This study suggests that the channel water balance approach, based on gauged streamflow and spring discharge, is more accurate when one incorporates groundwater basins delineated by groundwater tracing, especially in karst aquifers. Refinement of an appropriate catchment area for the calculation of autogenic recharge also significantly affected the results of a precipitation water balance.

New occurrence records for Eurycea sosorum Chippindale, Price & Hillis, 1993 (Caudata, Plethodontidae) in Travis and Hays counties, Texas, USA

“…To the north, the deeply incised Colorado River separates E. sosorum from a divergent clade of 3 Eurycea species that are restricted to the northern segment of the Edwards Aquifer (Chippindale et al 2000). To the south, a groundwater divide that shifts between the Blanco River and Onion Creek (Smith et al 2012, Hauwert 2016) separates E. sosorum from parapatric E. pterophila Burger, Smith & Potter, 1950 populations in the Blanco River basin ( Fig. 1; Chippindale et al 2000, Bendik et al 2013).…”

Barton Springs segment of the Edwards (Balcones Fault Zone) Aquifer, central Texas

“…3) when compared to the more regional sources that contribute flow to San Marcos and Comal Springs in the San Antonio segment of the Edwards Aquifer (Musgrove and Crow, 2012). Water-balance and geochemical studies indicate that most recharge occurs within streams that cross the recharge zone Slade, 2014Slade, , 2015Wong et al, 2012;Hauwert and Sharp, 2014;Hauwert, 2016). A summary of the range of recharge as a percentage of discharge and precipitation is presented in Table 2.…”

“…Recharge is highly variable in space, time, and soil-moisture conditions, as demonstrated by the ranges in percentage of recharge in Table 2 Other sources of recharge to the Barton Springs segment of the Edwards Aquifer are thought to be relatively small on the basis of the mean water-budget analysis (Slade, 2014;Hauwert, 2016). However, during drought conditions, the relative contribution of recharge for a given source can change significantly (Passarello et al, 2012).…”

“…During drought conditions, geochemical data have been interpreted to indicate that stream recharge comprises as little as 5% of spring flow (Mahler et al, 2006(Mahler et al, , 2011Wong et al, 2012). Another interpretation, supported by dye tracing and other data, is that conduit flow is still dominant during drought conditions and is sustained, in part, by recharge from the Blanco River (Hauwert, 2016) and intra-aquifer flow from the San Antonio segment (Land et al, 2011). Casteel et al (2013) reported a time-lagged increase in discharge and gauge height at Barton Springs in response to increases in recharge from the Blanco River during drought periods when all other contributing watersheds were dry.…”

“…This chapter summarizes the current understanding of Approximate area east of the freshwater-saline water interface to the edge of the Carrizo major aquifer boundary Note: Data from R. Gary, Barton Springs/Edwards Aquifer Conservation District (2013, personal commun.). *Within the recharge zone there are sub-groundwater basins such as the Cold Springs springshed, which is about 12 mi 2 (31 km 2 ; Hauwert, 2016).…”