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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

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

Shanna Evans

December 2, 2004

importance
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?

location chihuahuan desert
Location- Chihuahuan Desert

Blue points on Cuatro Cienegas Map are springs within the basin

Cuatro Cienegas

objectives
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
chemical data
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
building the geodatabase
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
objectives1
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
integrating chemical data into gis
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
integrating chemical data into gis1
Integrating Chemical Data into GIS

Each pink point is a sample site containing chemical data, but the data was stored in 4 layers!

integrating chemical data into gis2
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
objectives2
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
conductivity map
Spline and kriging methods were not accurate in their interpretation.

Inverse Distance Weighted method was most accurate

Conductivity Map!
objectives3
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
objectives4
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
chemistry and flow systems
Chemistry and Flow Systems??

5 flow systems most likely exist in the basin

chemistry and flow systems1
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??
chemistry and flow systems2
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??
chemistry and flow systems3
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??
conclusions and recommendations
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
references
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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