A review of regional hydrogeology studies in the Sacramento Mountains and Tularosa Basin Stacy Timmons, Geoff Rawling, Talon Newton, Shari Kelley, and Ethan Mamer Presenting work funded by NM Legislature through OSWCD + USGS NCGMP and National Park Service at White Sands National Monument New Mexico Bureau of Geology and Mineral Resources New Mexico Bureau of Geology & Mineral Resources A service and research division of New Mexico Tech. We serve as the geological survey for the state. Components of our mission: . Conduct research and interact with State and Federal agencies and industry to facilitate prudent exploitation of the state's geological resources. Distribute accurate information to scientists, decision makers, and the New Mexico public regarding the state's geologic infrastructure, mineral and energy resources, and geohydrology (including water quantity and quality). Create accurate, up-to-date maps (using GIS) of the state's geology and resource potential. Act as a repository for cores, well cuttings and a wide variety of geological data. Provide convenient physical and internet access for New Mexicans to such resources. New Mexico Bureau of Geology and Mineral Resources Aquifer Mapping at the Bureau of Geology What we do: . Characterize the quantity, quality and distribution of groundwater in aquifers using detailed information from geology, hydrology, geochemistry, and geophysics. Products: . Regional hydrogeology technical reports . Maps of subsurface groundwater features . Hydrogeologic models and detailed data for regional aquifers . Scientifically defensible planning tools New Mexico Bureau of Geology and Mineral Resources Two water planning regions geoinfo.nmt.edu/resources/water/amp New Mexico Bureau of Geology and Mineral Resources New Mexico Bureau of Geology and Mineral Resources Mountain area recharge New Mexico Bureau of Geology and Mineral Resources New Mexico Bureau of Geology and Mineral Resources Regional water table New Mexico Bureau of Geology and Mineral Resources Groundwater recharge estimates in the Sacramento Mountains Goals: . Quantify the timing, location, and quantity of groundwater recharge in the Sacramento Mountains . Relate the quantity to recharge estimates for the Roswell Artesian Basin Methods: . Quantify timing with stable isotopes . Quantify location with water chemistry and climatic data . Quantify amount with Cl mass- balance technique New Mexico Bureau of Geology and Mineral Resources Location of groundwater recharge Determining recharge area: 1. Can assume most recharge is within area where long-term average precipitation > evaporation 2. Freshest spring waters, youngest ages, changes in isotopic composition in idicates most recharge occurs above ~ 2380 m (7800 ft) 3. This is similar to the area where average annual precipitation > 58 cm 4. It is also the elevation at which the Cl concentration in groundwater stops changing… New Mexico Bureau of Geology and Mineral Resources Location and quantity of groundwater recharge Cl mass balance method: . Naturally occurring Cl in precipitation and dust enters groundwater . Evapotranspiration concentrates Cl . Degree of Cl concentration in groundwater determines percentage of recharge . Each water sample gives a recharge value . Wide range above 2380 m (7800 ft) due to water “recycling” . Values below 2380 m are best estimates of recharge % New Mexico Bureau of Geology and Mineral Resources Quantity of groundwater recharge Recharge to RAB from Total Recharge to Source Yeso Fm alone Method RAB (acre-feet/yr) (acre-feet/yr) Estimation of Fiedler and Nye 1 ≤ 235,268 ≤ 176,443 predevelopment 1933 discharge Correlation with 2 Hantush 1957 257,073 192,801 precipitation in 1928, 1936, 1944 Correlation with 3yr Saleem and Jacob 3 177,051 – 309,089 132,030 – 232,066 precip. (1903 – 1968 1971 avg.) 4 Summers 1972 231,961 173,946 Water budget 5 Duffy et al. 1978 - 133,035 Darcy calculation 6 DBSA 1995 260,072 175,049 Flow model calibration Present study – 129,631; 7a above 2380 m elv. - Chloride mass balance 88,152 – 171,117 contour Present study – 178,291; 7b above 58 cm - Chloride mass balance 120,795 – 234,490 precip. contour New Mexico Bureau of Geology and Mineral Resources Watershed study New Mexico Bureau of Geology and Mineral Resources The Sacramento Mountains Watershed Study New Mexico Bureau of Geology and Mineral Resources Tree thinning New Mexico Bureau of Geology and Mineral Resources Soil water balance New Mexico Bureau of Geology and Mineral Resources Effects of tree thinning • Canopy interception decreases – More water reaches the ground. • Runoff does not change significantly. • Net transpiration decreases (at least in the short- term). • Soil water evaporation increases. New Mexico Bureau of Geology and Mineral Resources Potential ET – The amount of evaporation that would occur if a sufficient amount of water were available • In the Southwestern US, potential ET greatly exceeds the average annual precipitation rates. • Both evaporation and transpiration are driven by same factors • Solar radiation • Air temperature • Humidity • Wind • An increase in water storage in the shallow soil will result in an increase in evaporation rates. New Mexico Bureau of Geology and Mineral Resources Infiltration and storage of water in soils New Mexico Bureau of Geology and Mineral Resources Good news – Preferential flow New Mexico Bureau of Geology and Mineral Resources Conclusions • Evidence suggests that tree thinning in the Sacramento Mountains does increase potential groundwater recharge. • This treatment is suitable for settings where the shallow hydrologic system is local. • Tree thinning is recommended for many reasons, but not for the sole purpose of increasing large- scale groundwater recharge New Mexico Bureau of Geology and Mineral Resources Local hydrogeology New Mexico Bureau of Geology and Mineral Resources Where and when will we see a response to thinning? New Mexico Bureau of Geology and Mineral Resources Recommendations Tree thinning to increase water supply . watersheds, where springs and shallow groundwater is local Tree thinning as a forest restoration technique . Above 8000 feet elevation . Decrease fire hazard . Improve wildlife habitat . PROTECT RECHARGE AREA New Mexico Bureau of Geology and Mineral Resources Tularosa Basin - Geology New Mexico Bureau of Geology and Mineral Resources Tularosa Basin & the Rio Grande rift Colorado Plateau New Mexico Bureau of Geology and Mineral Resources Regional Geology NM State Geology map (Bureau of Geology, 2003) Scale of 1:500,000 (1 in ~ 42000 ft) New Mexico Bureau of Geology and Mineral Resources Detailed geologic mapping Two compilation maps at a scale of 1:50,000 (~1 in ~ 4200 ft) Compilation maps compiled using geologic mapping from 17 1:24,000 scale quadrangles New Mexico Bureau of Geology and Mineral Resources Southern compilation map Northern compilation map New Mexico Bureau of Geology and Mineral Resources New Mexico Bureau of Geology and Mineral Resources Tularosa Basin hydrology New Mexico Bureau of Geology and Mineral Resources Water table maps Northern region Southern region New Mexico Bureau of Geology and Mineral Resources Mountain Front Recharge (MFR) Water drains from nearby mountains and recharges the adjacent basin aquifer. Occurs at the mouths of drainage basins, where perennial and ephemeral streams flow into the basin and infiltrate into the porous alluvial fans. Previous study (Waltemeyer, 2001) calculated using the ‘Basin-Climatic Characteristic Method.’ This equation takes into account: The area of various drainages that discharge into the Tularosa Basin The average annual precipitation of each basin based on its mean elevation. New Mexico Bureau of Geology and Mineral Resources Mountain Block Recharge (MBR) Groundwater that recharges at high elevations Flows through the mountain-block, before entering the basin-fill aquifer. The difference between the ‘Total Darcy Flow’ estimation and the published mountain front recharge approximation. Mountain Block = Darcy Flow – Mountain Front New Mexico Bureau of Geology and Mineral Resources Darcy Flow New Mexico Bureau of Geology and Mineral Resources Hydraulic Gradient Change in elevation by change in distance : slope of water table North Transect South Transect Central Transect New Mexico Bureau of Geology and Mineral Resources Hydraulic Conductivity (K) Describes the ease with which water flows through an aquifer Large degree of spatial variability > e.g. Basin Fill Sediments e.g. Fractured Volcanics New Mexico Bureau of Geology and Mineral Resources Saturated Thickness of Aquifers (A) North Transect Estimated Hydraulic Conductivity (K) TKSCC: 2 ft/day GLUP: 0.01 ft/day Darcy Flow: 4,600 AFY ~650 AFY per mile MFR: 4,300 AFY New Mexico Bureau of Geology and Mineral Resources Saturated Thickness of Aquifers (A) Central Transect Estimated Hydraulic Conductivity (K) QTBF: 0.6 ft/day TKSCC: 0.2 ft/day GLUP: 0.001 ft/day Darcy flow: 4,300 AFY ~350 AFY per mile MFR: 640 AFY New Mexico Bureau of Geology and Mineral Resources Saturated Thickness of Aquifers (A) South Transect Estimated Hydraulic Conductivity (K): QTBF: 6 ft/day TWL: 3 ft/day Darcy Flow: 60,000 AFY ~2,600 AFY per mile MFR: 40,300 AFY New Mexico Bureau of Geology and Mineral Resources Recharge Summary . 67,900 AFY of recharge in this section of the Tularosa Basin . 66% as Mountain-Front Recharge: mouth of drainage basins . 33% as Mountain-Block Recharge: deeper flow paths ~ 9% of precipitation results in recharge (up to 22% in Sacramento Mtn study) MFR