Preliminary groundwater storage changes from 1950s to present in New Mexico alluvial aquifers using a semi-automated workflow

Abstract

In response to increasing needs to understand the water budget of New Mexico, we have constructed estimates of historical groundwater storage change in the shallow (less than 1000 ft), unconfined alluvial aquifers of the state. Shallow, unconfined alluvial aquifers in New Mexico form the major groundwater reservoirs in many of the urbanized and agricultural areas of the state. This collocation means that alluvial aquifers have been commonly used as a major water source over the last 70 years, possibly leading to declines in storage through time. We present preliminary estimates of historical groundwater storage changes in the alluvial aquifers of New Mexico, separated by USGS HUC-8 (hydrologic unit code, level 8) boundaries. These aquifers are mostly in Rio Grande and Basin-and-Range physiographic provinces-they are either in basins with the Rio Grande flowing through them or they are in the closed basins to the east and west of the Rio Grande basins. Our estimates are based on depth-to-water measurements available from the USGS online database, and datasets that conform to USGS measurement standards. Water level measurements affected by pumping or those that were taken during irrigation season were removed, except for locations in rangeland areas with poor data coverage. The measured depths-to-water are then used to determine a correlation length of water levels for each basin for every decade from the 1950s to present. The water levels are then interpolated using both ordinary kriging and inverse-distance-weighting methods. The interpolated fields are restricted to the radius of correlation lengths, and to Quaternary sediments mapped at the 1:500,000 scale.While our results are preliminary, we see a few patterns beginning to emerge. Groundwater withdrawals in closed basins appear to vary by the proportions of the water balance-pumping rates and locations compared with recharge rates and locations. In open basins, such as the El Paso-Las Cruces HUC or the Albuquerque HUC, the storage changes appear to be linked to the degree of connection of groundwater with the surface water, pumping demands and the presence of mountain-block recharge. Open basins are less sensitive than closed basins to pumping demands as long as (a) there is an initial connection with surface water, and (b) pumping does not lower the water to the point that the groundwater does not respond strongly to annual river flows. The Albuquerque HUC is a case where both of these conditions are met. The Santa Fe HUC and El Paso-Las Cruces HUCs, respectively, are examples of behaviors when (a) and (b) are not met, and groundwater is currently lowering due to greater demand independent of the river. Our results provide a coarse resolution view of groundwater storage in New Mexican alluvial aquifers. They do provide direct examples of how geology, hydrology and society are reflected in our groundwater resources at the basin scale.

Winter 2019�2020 Water-Level Elevation Map for the Albuquerque Metropolitan Area

“…It must be viewed with caution because the result is highly dependent on the value for specific yield, which must be assumed in this case. A value of 0.2 was chosen for this study, consistent with previous work (McAda and Barroll, 2002;Rinehart et al, 2016). It is likely that the specific yield varies in space, with depth, and with lithology (e.g., Cederstrand and Becker, 1998).…”

Sunshine Valley hydrogeology study

“…This can be roughly estimated with a few simple calculations. The loss from storage can be estimated first using an intermediate, uniform water-level decline value of 2 feet per year for the period of the 1950s to the 2010s, and a specific yield value of 0.15 (Rinehart et al, 2016) over the total area of surficial and valley-fill deposits in Sunshine Valley (363 km 2 ) (Fig. 4 and 6).…”

“…Comparing the 1950s to the 2010s decades directly, the total loss from storage was 73,487 acre-feet, or an average of 1124 acre-feet/year over 60 years. Rinehart et al (2016) calculated water-level and groundwater-storage changes in alluvial basins of the Rio Grande rift, including the Sunshine Valley region. From the 1950s to the 1990s, Rinehart et al (2016) indicated a similar pattern of variably rising and falling water levels across much of Sunshine Valley, as illustrated in Figure 9.…”

“…Rinehart et al (2016) calculated water-level and groundwater-storage changes in alluvial basins of the Rio Grande rift, including the Sunshine Valley region. From the 1950s to the 1990s, Rinehart et al (2016) indicated a similar pattern of variably rising and falling water levels across much of Sunshine Valley, as illustrated in Figure 9. Their interpolations covered a larger area than the water-level surfaces in the present study, so for comparison, the storage changes of Rinehart et al (2016) were recalculated within the area of the 1980s water-level surface presented here.…”

Collapsible Soil Susceptibility Map for New Mexico (1:750,000) Based on Multiple Proxies

“…where sdtw is the susceptibility based on the median DTW and d is the median DTW. These thresholds were chosen based on observations of normal annual to decadal variations of groundwater levels in basin-fill aquifers across the state observed by Rinehart while conducting a statewide groundwater change analysis (Rinehart et al, 2015(Rinehart et al, , 2016(Rinehart et al, and 2017. Regions with deeper groundwater are more likely to have never flooded and been saturated through the entire thickness.…”