Statistical Clustering of Major Solutes: Use as a Tracer for Evaluating Interbasin Groundwater Flow into Indian Wells Valley, California

Abstract

Many previous studies have demonstrated use of specific solutes or isotopes as tracers of groundwater flow. We present a technique that uses standard hydrochemical information to create statistically based hydrochemical facies, which are then used as tracers of groundwater flow. This approach reduces potential subjective bias during interpretation of single tracer data in complex systems with multiple sources or conflicting multiple tracer data. Standard hydrochemical data from 1,368 water samples that spanned more than 80 years were analyzed using cluster analysis to decipher groundwater flow paths in Indian Wells Valley (IWV), California. The statistically derived hydrochemical facies form distinct spatial patterns in which all major-ion concentrations increase progressively from Sierra Nevada (recharge) to China Lake playa (discharge), consistent with the topographically driven flow of groundwater (the typical case for basin and range flow systems). However, once individual samples could be placed in the context of the normal hydrochemical evolution, anomalies are readily identifiable. The distribution of water chemistry in the southeastern part of the IWV does not conform to the regional trend. Groundwater from that part of the IWV is statistically more similar to waters from the Kern Plateau area (in the high Sierra Nevada outside the local watershed) than to waters from the local watershed. The groundwater is interpreted to originate from the fracture-directed interbasin flow from the Kern Plateau area that is directly recharging the alluvial aquifer in the subsurface. Inclusion of this flow could substantially alter current water budgets and water resources management approaches.

Spring temperatures in the Sagehen Basin, Sierra Nevada, CA: implications for heat flow and groundwater circulation

“…Another possibility is that some of the water originated in higher elevation basins. Güler & Thyne (2006) found evidence for interbasin flow in the southern Sierra Nevada, and Sylvester (2007) has suggested that groundwater from Independence Lake might feed springs on the western side of the basin. While there is no direct evidence for this, the possibility of interbasin flow is a concern in any area where the hydrogeology has not been studied in detail.…”

How realistic are water‐balance closure assumptions? A demonstration from the southern sierra critical zone observatory and kings river experimental watersheds

“…Catchments may also be leaky at river‐basin scales. Güler and Thyne (2006) used geochemical tracers to show that water originating in the Kern could be found in a different river basin on the eastern side of the Sierra Nevada. As a fraction of the overall water balance, this amount is likely to be smaller for river basins than for catchments.…”

“…Furthermore, the subsurface structure of the critical zone has been identified as the biggest knowledge gap in the effort to incorporate hillslope-scale hydrological processes into Earth System Models (Fan et al, 2019) Catchments may also be leaky at river-basin scales. Güler and Thyne (2006) used geochemical tracers to show that water originating in the Kern could be found in a different river basin on the eastern side of the Sierra Nevada. As a fraction of the overall water balance, this amount is likely to be smaller for river basins than for catchments.…”

Are catchments leaky?

“…In doing so, they "bookended" the intercatchment groundwater transfer, showing its termination at the second catchment in a three-catchment catena (Figure 11). Güler and Thyne (2006) traced the origin of the shallow groundwater in the Indian Wells Valley (IWV), below the eastern flank of Sierra Nevada Range in southern California, to source regions outside of the topographic basin. Geochemical clustering analysis pinpointed chemical facies diagnostic of water sources, tracing groundwater flow via dense fractures from the Sierra Nevada mountains west of the topographic divide.…”