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Determining Flow Systems Using Chemical Data and GIS in Cuatro Cienegas, Coahuila, Mexico

Determining Flow Systems Using Chemical Data and GIS in Cuatro Cienegas, Coahuila, Mexico. Shanna Evans December 2, 2004. Importance. The basin was set aside as a preserve by the Mexican government in 1994 More than 70 endemic and/or endangered species inhabit the basin (DFWC, 2003)

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Determining Flow Systems Using Chemical Data and GIS in Cuatro Cienegas, Coahuila, Mexico

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  1. Determining Flow Systems Using Chemical Data and GIS in Cuatro Cienegas, Coahuila, Mexico Shanna Evans December 2, 2004

  2. Importance The basin was set aside as a preserve by the Mexican government in 1994 More than 70 endemic and/or endangered species inhabit the basin (DFWC, 2003) It has a spring density of 12-15 pozas (spings) per square kilometer (Winsborough, 1990) Water levels have dropped approximately 30-60 cm in the past five years (Lesser, 2001) Where is the water coming from and where is it going?

  3. Location- Chihuahuan Desert Blue points on Cuatro Cienegas Map are springs within the basin Cuatro Cienegas

  4. Objectives • Integrate water chemistry for the Cuatro Cienegas Basin into GIS • Provide conductivity map to examine chemistry in the basin • Demonstrate temperature variations in the basin • View spatial variability of chemistry to examine flow paths

  5. Water samples and corresponding GPS locations were collected at 35 sites during April and June, 2004. Samples were analyzed for major anions and cations Conductivity, pH, DO, ORP, Temperature, and alkalinity were measured in the field Poza Juan Santos Chemical Data

  6. Building the Geodatabase • Base files from Jennifer Howeth and A. Moline were in geographic and projected formats (NAD-1927 and UTM) • 6 Feature Datasets were created for the basin • CC lies in UTM zone 13 and zone 14 • All GIS data was finally projected into the UTM Zone 13 format

  7. Objectives • Integrate water chemistry for the Cuatro Cienegas Basin into GIS • Provide conductivity map to examine chemistry in the basin • Demonstrate temperature variations in the basin • View spatial variability of chemistry to examine flow paths

  8. Integrating Chemical Data into GIS • Problems!!! • GPS positions taken in the field were in UTM Zone 13 and Zone 14 • Some sample sites did not have locations associated with them • Solutions!!! • Data were separated into 4 spreadsheets and saved as dbf4 files: • Zone 13 • Zone 14 • No data with known XY location from other source • No data without known XY location

  9. Integrating Chemical Data into GIS Each pink point is a sample site containing chemical data, but the data was stored in 4 layers!

  10. Integrating Chemical Data into GIS • Excel spreadsheets and the Add XY tool saved the day! • The layers were combined into one for chemical data interpolation

  11. Objectives • Integrate water chemistry for the Cuatro Cienegas Basin into GIS • Provide conductivity map to examine chemistry in the basin • Demonstrate temperature variations in the basin • View spatial variability of chemistry to examine flow paths

  12. Spline and kriging methods were not accurate in their interpretation. Inverse Distance Weighted method was most accurate Conductivity Map!

  13. Objectives • Integrate water chemistry for the Cuatro Cienegas Basin into GIS • Provide conductivity map to examine chemistry in the basin • Demonstrate temperature variations in the basin • View spatial variability of chemistry to examine flow paths

  14. IDW and Spline Temperature Map Kriging Temperature map Temperature Maps!

  15. Objectives • Integrate water chemistry for the Cuatro Cienegas Basin into GIS • Provide conductivity map to examine chemistry in the basin • Demonstrate temperature variations in the basin • View spatial variability of chemistry to examine flow paths

  16. Chemistry and Flow Systems?? 5 flow systems most likely exist in the basin

  17. Higher conductivities were at the end of flow paths and toward the center of the basin Evaporation controls chemical evolution This is consistent with the proposed flow systems Conductivity map of the basin Chemistry and Flow Systems??

  18. Higher temperatures were at the source of the spring and toward the end of the flow paths Interesting, but not necessarily helpful Temperature map of the basin Chemistry and Flow Systems??

  19. Alkalinity in the basin may be an indicator of separate flow systems The Anteojo and Hundidos systems had the highest alkalinities Alkalinity map of the basin Chemistry and Flow Systems??

  20. Conclusions and Recommendations • GIS is a useful tool in viewing chemical data to analyze flow systems based on spatial variability • GIS alone cannot interpret the chemical data- one must know the chemical processes involved • In order to obtain a more accurate chemical data map, more springs in the basin must be analyzed

  21. References • Desert Fishes Council Web. 2003, Cuatro Cienegas Home Page, http://www.desertfishes.org/cuatroc/index.html, maintained by Dean A. Hendrickson. • Lesser & Associates, and Gerencia de Aquas Subterraneas. 2001, Hydrologic Synopsis en the Hundido, Cuatrocienegas, and Ocampo Valleys, Coahuila, Evaluation Report for the Commission Nacional de Aguas, Mexico City, Mexico. • Winsborough, Barbara, 1990. Some ecological aspects of modern fresh-water stromatolites in lakes and streams of the Cuatro Cienegas Basin, Coahuila, Mexico, The University of Texas- Austin Dissertaion, 341 pp.

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