1. Evaluation of Management Alternatives in the San Acacia Reach Based on High-Resolution Modeling Robert Bowman and Laura Wilcox, Department of Earth and Environmental Science New Mexico Tech Nabil Shafike New Mexico Interstate Stream Commission

2. Acknowledgements Collaborators Collaborators –SS Papadopulos & Associates Funding Agencies Funding Agencies –NM Interstate Stream Commission –US Army Corps of Engineers

3. Motivation for Understanding: Better Balance of Competing Demands Agriculture Agriculture Municipal/Industrial Municipal/Industrial Environmental Environmental Interstate Interstatecompacts

4. The San Acacia Reach: Critical for Rio Grande Compact Compliance

5. Relevant Issues Water consumption by riparian vegetation Water consumption by riparian vegetation Removal of exotic vegetation Removal of exotic vegetation Environmental effects of drying of the river Environmental effects of drying of the river Potential engineering alternatives Potential engineering alternatives

6. Demands On Water Resources

7. Study Area Socorro Main Canal Low Flow Conveyance Channel San Acacia Diversion Dam Aerial view of San Acacia Diversion Dam, looking southwest Elephant Butte Dam Aerial view of Elephant Butte Reservoir and Dam, looking northeast

8. CONCEPTUAL MODEL OF WATER DYNAMICS River flow irrigation precipitation Groundwater recharge and discharge West East drain LFCC Rio Grande Well pumping transpiration evaporation LFCC gain Groundwater recharge and discharge

9. Approach to Determining Surface Water/Groundwater Interactions Water dynamics Water dynamics Water chemistry Water chemistry Hydrologic modeling Hydrologic modeling

10. Water Dynamics Determine connectivity between surface water bodies Determine connectivity between surface water bodies Determine groundwater response to changing river stage Determine groundwater response to changing river stage Evaluate temporal changes Evaluate temporal changes

11. Monitoring Network 7 transects over ~50 miles 7 transects over ~50 miles ~175 monitoring wells ~175 monitoring wells 25 surface-water-level gauges 25 surface-water-level gauges ~70 transducers taking hourly water level readings ~70 transducers taking hourly water level readings

12. Monitoring Transect Cross Section Socorro Main Canal LFCC Rio Grande

13. LFCC Rio Grande SRD Rio Grande LFCC Groundwater Wells Groundwater Levels Rise in Winter

14. LFCC Rio Grande Groundwater Wells LFCC Groundwater Levels Rise in Winter

15. Groundwater Responds to ET

16. Groundwater Responds to Flooding

17. Hydrological Modeling Integrate current understanding of GW/SW interactions Integrate current understanding of GW/SW interactions Evaluate operations of the river and the LFCC Evaluate operations of the river and the LFCC Evaluate impact of groundwater levels on riparian ET Evaluate impact of groundwater levels on riparian ET Investigate management alternatives Investigate management alternatives

18. Key Data Collected Geologic Data Stratigraphy (color, grain size, hydraulic conductivity) Stratigraphy (color, grain size, hydraulic conductivity) Aquifer Data Hydraulic conductivities (aquifer testing) Hydraulic conductivities (aquifer testing) Water-elevation time series Water-elevation time series

19. Stratigraphy Legend No Sample Clay, Sandy Clay Silt, Silt & Fine Sand Fine Sand Fine to Medium Sand, Medium Sand Fine to Coarse Sand, Coarse Sand Sand and Gravel, Gravel Clayey Gravel Santa Fe Group Bedrock Water Surface 400 ft 20 ft HWY-W02 HWY-E01 HWY-E02 HWY-E03 East Rio Grande 4560 4540 4520 4500 4480 4460 HWY-W06 HWY-W03 HWY-W04 LFCC HWY-W07 Valley alluvium Santa Fe Formation Layer 3 Layer 2 Layer 1 West

20. Aquifer Testing

21. Aquifer Test Instrumentation 0.5 miles north of Highway 380 in San Antonio Socorro Riverside Drain LFCC Rio Grande Legend Well 0-20 feet Well 40-50 feet Well 80-90 feet Staff gage Extraction well 10 07 09 LFCC Rio Grande Low-permeability zone

22. Time-drawdown of nested well W07A,B,C r of W07 = 15 feet Legend Well 0-20 feet Well 40-50 feet Well 80-90 feet LFCC Rio Grande Low-permeability zone

23. AREA OF INTEREST FOR HIGH-RESOLUTION MODELING Magdalena Mountains N Socorro San Antonio 60 380 San Acacia I-25 San Marcial Rio Grande Regional model - ISC Telescopic model -smaller domain -refined grid -constant head from regional model

24. River water losses in this reach are extreme

25. Domain is 320 rows x 170 columns = 54400 grid cells OR 6 miles x 3 miles = 18 miles 2 regional model grid is 1000 feet x 1000 feet Telescopic model grid is 100 feet x 100 feet MODEL CONSTRUCTION - Model Grid

26. Layer 1 - sand 0 feet 35 feet Layer 3 - sand/gravel 0 feet 75 feet Layer 2 - clay/silt Three-Layer Model

27.  Designation of grid cells to represent drains, LFCC, and river.  Each cell has values for: stage conductance bottom elevation bed thickness vertical hydraulic conductivity Surface Water System

28. Stream –aquifer System Representation of Stream –aquifer System River Surface Water Table Streambed River Stage (HRIV) Impermeable Walls M W RBOT Riverbed Conductance = KLW M MODFLOW River Package: - Riv1 (MODFLOW 83) Land Surface Head in Cell (h)

29. Estimation of River Stage

30. Evapotranspiration Riparian Crops Legend Crop and pasture Riparian Sandbars Other or inactive IKONOS – July 2000

31. Prescribed Head regional model Constant head boundary determined from regional model for every stress period telescopic model

32. Groundwater Budget Model Calibration

33. Removal of the Low Flow Conveyance Channel Relocation of the River Channel Decrease in Riparian Evapotranspiration EVALUATION OF MANAGEMENT ALTERNATIVES

34. Effects of Removing the LFCC Groundwater levels rise 8% increase in riparian ET Seepage from river decreases by ~70% Without LFCC With LFCC

35. Evaluation of Relocation of River Channel Present day Rio Grande location LFCC Neil Cupp Highway 380 N Simulated Rio Grande location LFCC Neil Cupp Highway 380 0.5 Miles N W-91.28-1 W-Perini W-91.28-1 W-Perini

36. Effect of Channel Relocation Groundwater rises to the east of the river 2% decrease in riparian ET Seepage losses from the river decrease by 34% Original channel Relocated channel

37. Effect of Decreased Riparian ET Groundwater rises to the east of river 50% decrease in riparian evapotranspiration translates to a 6% decrease in river seepage

38. Conclusions The Rio Grande and the shallow groundwater system are highly interconnected The Rio Grande and the shallow groundwater system are highly interconnected Most of the shallow groundwater is of Rio Grande origin Most of the shallow groundwater is of Rio Grande origin Channel adjustments and control of riparian vegetation can increase river flows Channel adjustments and control of riparian vegetation can increase river flows

39. Rio Grande Project Robert S. Bowman, Robert S. Bowman, Professor of Hydrology Project Home Study Area Recent Results Calendar Presentations Modeling Efforts Students Associated Organizations Photo Gallery Welcome to the Rio Grande Project Website! The Rio Grande supports much of New Mexico agriculture and industry. With headwaters in Colorado and a terminus in the Gulf of Mexico, political, trans-state-boundary conflicts have existed for decades. In an effort to distribute water in a fair manner, the Rio Grande Compact was signed by the three US states and Mexico in 1938. The signing of this compact forced New Mexico into a debt/credit system of water delivery to Texas. Maintaining a fair and even balance of water distribution in New Mexico while continuing to deliver the appropriate volume of water downstream is a daunting task. The goal of this project is to study the surface water/groundwater interactions between San Acacia and Elephant Butte Dam. This reach of the Rio Grande shows distinct losses to the shallow aquifer and if a better understanding of the system is achieved, it may be possible to more efficiently deliver water to Elephant Butte Reservoir and ultimately, Texas. This is a joint project funded by the ISC and Army Corps of Engineers, under the authority of Section 729 of the Water Resources Development Act. STUDY AREA STUDY AREA What area of the river are we studying? Where are the new wells going to be drilled? CALENDAR CALENDAR Meetings and conferences? Sampling? Water level measurements? Drilling? Pump tests? See what we are up to now. PRESENTATIONS PRESENTATIONS Want to learn more? Check out our latest abstracts and presentations. MODELING EFFORTS MODELING EFFORTS A coupled surface water/groundwater model is currently being finalized and will aid in the creation of a refined model of the region between Luis Lopez and HW 380. STUDENTS STUDENTS Currently there are three students working on this project, two hydrology masters degree candidates and one undergraduate geophysics student. ASSOCIATIONS ASSOCIATIONS Who else is involved with this project? Where does the money come from? RECENT RESULTSUpdated November 3, 2002by Laura WilcoxRecent data shows rising water levels with the onset of the monsoon. Latest water quality sampling (June) shows roughly the same trends as February except that the River displays LFCC trends in the south. (click here for graphs and other cool stuff) RECENT RESULTSUpdated November 3, 2002by Laura WilcoxRecent data shows rising water levels with the onset of the monsoon. Latest water quality sampling (June) shows roughly the same trends as February except that the River displays LFCC trends in the south. (click here for graphs and other cool stuff) HomeHome | Geology | Geochemistry | Hydrology | Geophysics | Site Map | ContactGeologyGeochemistryHydrologyGeophysicsSite MapContact Last Updated: November 3, 2002Last Updated: November 3, 2002 For More Information… www.ees.nmt.edu\bowman\research\RioGrandeProject