Jordan HowardGeorgia Southern University

June 23 - August 7, 2014Summer REU 2014

A WEST SIDE STORYSTRATIGRAPHIC CONTROLS ON GROUNDWATER FLOW IN THE EL RITO

WATERSHED

ARE SPRINGS CORRELATED TO

ASPECT AND GEOLOGIC UNIT?

BACKGROUND

LOCATIONS OF EL RITO AND CANJILON WATERSHEDS

HYPOTHESIS• Springs in the El Rito watershed emerge in specific

aspects based on the attitudes of underlying stratigraphic units. Dips of these units control inter-basin flow between the Canjilon and El Rito watersheds and determine spring emergence areas due to their controls on groundwater flow (i.e. permeability, porosity, erosional impacts, etc.).

WHY IS THIS HYPOTHESIS IMPORTANT?

• Knowing where springs emerge with respect to geologic units provides insight into groundwater flow-paths and residence times

• If springs are restricted to one or two geologic units, what happens when erosion completes its course in groundwater bearing sediments?

• Helps provide insight to regional groundwater and surface-water interactions

METHODS

• Analyzing Google Earth images, ortho-images, and forest service maps

• Recording UTM coordinates of springs

• Measuring dips of outcrops near spring emergence areas and taking note of sediments/outcrops near spring emergence sites

• Taking pictures of spring sites and plotting spring sites on GIS to correlate them with surrounding stratigraphy

• Taking water samples & using YSI gauge (pH and conductivity)

GIS Map Showing Spring Locations with Respect to

Geologic Unit

-Green dots represent springs found during research

-Yellow line represents the El Rito watershed divide

-Blue line represents El Rito Creek, and the blue lines surrounding the Creek are contributing streams

-Geologic Unit Key:

Light pink: Ritito Formation (Cenozoic)

Dark pink: El Rito Formation (Cenozoic)

Green: Mancos Shale (Mesozoic)

GEOLOGIC UNIT DESCRIPTIONS(IN CHRONOLIGICAL ORDER)

• Ritito: Cenozoic; poorly-lithified conglomerate; light color

• El Rito: Cenozoic; well-lithified conglomerate; darker (reddish) color

• Mancos: Mesozoic; shale

Eastward Dipping Cenozoic Units (Dips

range from 3-19 degrees)Westward Dipping

Mesozoic Units (Dips range from 16-39

degrees)

Mancos (Mesozoic)

El Rito (Cenozoic)

Ritito (Cenozoic)

SIGNIFICANCE OF RITITO FORMATION IN EL RITO AND CANJILON

What about inter-basinal

flow?

• pH levels

• Conductivity levels

• Age dating

INTER-BASINAL FLOW (CONT’D.)

Upstream (near 15 springs)

Downstream (near losing reach)

ADDITIONAL STRUCTURAL CONTROLS ON EASTERN SLOPES?

CONCLUSIONS

• Do regional dips correlate with spring aspects in the El Rito watershed?

• Does inter-basinal flow occur between the Canjilon and El Rito watersheds?

• Stratigraphic controls help us better understand groundwater and surface water interactions (losing/gaining reaches).

QUESTIONS??