IDENTIFICATION OF GEOLOGIC LINEAMENTS AND GROUNDWATER FLOW SYSTEMS, USING DIGITAL ELEVATION MODELS, SATELLITE IMAGERY, AND SPRING. Miriam Rios-Sanchez

Transcription

1 IDENTIFICATION OF GEOLOGIC LINEAMENTS AND GROUNDWATER FLOW SYSTEMS, USING DIGITAL ELEVATION MODELS, SATELLITE IMAGERY, AND SPRING DATA IN QUITO, ECUADOR Miriam Rios-Sanchez

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3 PROBLEM STATEMENT Quito area is located in the Ecuadorian Andes, is a basin conformed by volcanic sediments and surrounded by volcanic and metamorphic rocks and active volcanoes The exploration of groundwater resources in Quito Area, developed mainly for the Quito Water Company (EMAAP-Q), has been focused only in the volcanic sediments where some water wells have drilled to tap shallow aquifers. Fractured rocks have not yet been considered as potential aquifers However, fractures can act as discharge or recharge areas than can affect the groundwater balance in the area

4 PROBLEM STATEMENT (continued) Satellite Imagery has proven to be a useful tool to characterize groundwater resources in fractured rocks because of the ability of displaying extended large-scale structural elements across large regions. Also, remote sensing offers the opportunity to evaluate groundwater flow systems using thermal imagery, springs and topographic analysis. In equatorial areas, recharge areas along fractures normally are cooler than the surroundings and discharge areas are often warmer (Bobba et al., in Meijerink 2004 & Manga,2001)

5 NONO GUAYLLABAMBA CAYAMBE NONO GUAYLLABAMBA NONO GUAYLLABAMBA CAYAMBE QUITO QUITO QUITO ANTISANA ANTISANA ANTISANA COTOPAXI Kilom eters Miles Bands 7,5,4 (30m pixel resolution) COTOPAXI Bands 6 (90m pixel resolution) ETM+ LANDSAT IMAGE DEM

6 FLOWCHART 1. DOWNLOAD DATA AND PRE-PROCESSING DIGITAL ELEVATION MODEL (50m) Marc Souris IRD website ETM+ LANDSAT IMAGE (Bands 1,2,3,4,5,6 & 7) Global Land Cover Facility GEOLOGY/HYDROGEOLOGY (Faults and Well Inventory) Ecuador National Institute of Hydrology and Meteorology (1) DEM Layer 3) Composite Bands Layer (6) FAULTS Layer (2) HILLSHADE Layer (4) PCA Layer ( PC1, PC2 & PC3) (7) SPRINGS Layer (5) RADIANCE Layer

7 NONO GUAYLLABAMBA CAYAMBE NONO GUAYLLABAMBA CAYAMBE QUITO QUITO ANTISANA ANTISANA COTOPAXI COTOPAXI Kilometers Legend Radiance watts/(m2 ster µm)

8 2. PROCESSING DATA 2.1 CREATION OF LINEAMENTS MAP 2.2 IDENTIFICATION OF GROUNDWATER RECHARGE AREAS 2.2 IDENTIFICATION OF GROUNDWATER DISCHARGE AREAS IDENTIFICATION OF LINEAR FEATURES ON (1) DEM (Topography) (2) HILLSHADE (Topography) (3) PCA (Geological structures) (4) 4,3,2 Composite Landsat (6) Faults Layer OVERLAY (8) LINEAMENTS MAP (5) RADIANCE MAP OVERLAY (8) LINEAMENTS MAP WITH (5) RADIANCE MAP OVERLAY (5) RADIANCE MAP (7) SPRINGS LAYER DIGITIZING LINEAMENTS FOUN ON SEVERAL LAYERS CLASIFICATION OF LINEAMENTS AS POTENTIAL RECHARGE AREA** 1. There is a Lineament and 2. There are Low radiance values (in comparison to the surroundings) 3. Assign a field value as potential for recharge CLASIFICATION OF LINEAMENTS AS POTENTIAL DISCHARGE AREA 1. There is a Lineament and 2. There are High radiance values (in comparison to the surroundings) 3. Assign a field value as no potential for rechargel CLASIFICATION OF AREAS AS POTENTIAL DISCHARGE ` AREA 1. There is a spring of a group of springs 2. There are High radiance values (in comparison to the surroundings) ( 8) LINEAMENTS LAYER GENERATION OF RECHARGE ZONES 1. Buffer of 300m. (for Lineaments classified as potential recharge areas 2. Dissolve (to create non overlapping polygons) DIGITIZE THE POLYGON ON DISCHARGE SHP FILE ( 9) RECHARGE LAYER ( 10) DISCHARGE LAYER

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11 Lineament Map NONO GUAYLLABAMBA CAYAMBE NONO GUAYLLABAMBA QUITO QUITO QUITO ANTISANA ANTISANA ANTISANA COTOPAXI COTOPAXI

12 MAP 6. POTENTIAL GROUNDWATER RECHARGE AND DISCHARGE ZONES OF QUITO AREA (BASED ON LINEAMENTS, SPRINGS AND THERMAL IMAGERY) NONO CAYAMBE GUAYLLABAMBA QUITO Legend ANTISANA cities volcanoes Springs Discharge areas Recharge areas COTOPAXI

13 CONCLUSIONS Landsat Imagery, Principal Component Analysis and DEM are very useful tools to identify geologic/geomorphologic lineaments. Thermal Imagery (Reflectance) shows a very interesting correlation with mapped lineaments. This map could be used as an orientation of future works to prove the assumption of lineaments/fractures acting as recharge/discharge areas. Fracturing is an important factor in the geologic conditions of Quito Area and further work should be done to characterize it in terms of the potential for groundwater resources.

14 Creating a Composite Map for Use in Selection of Possible Sites for New Well Placement near Quito, Ecuador ROB HEGEMANN

15 Combine: Existing well locations Lineament locations Map of porosity derived from geologic map km mi

16 Well and Lineament Locations km mi km mi

17 Porosity Map (Digitized Geology) Geologic units were classified based on description as: No Porosity Primary Porosity Secondary Porosity km mi

18 2. PROCESSING DATA 2.2 Conversion to raster (pixel size 1000m x1000m) Lineament Layer Well Layer Geology Layer Lineament Raster Well Raster Geology Raster Lineament Raster Well Raster Geology Porosity Raster Lineament: No Data (0) All values (10) Wells: No Data (0) All values (1) Geology: Primary porosity (100) Secondary porosity (200) No porosity (0) 2.3 Reclassify Values 3. PRODUCTION OF COMPOSITE MAP FOR GROUNDWATER POTENTIAL Lineament Raster Well Raster Geology Raster 3.1 Raster Calculator Sum raster values Composite Raster

19 Composite Map Quito No Porosity No Porosity, Wells No Porosity,Lineaments No Porosity, Lineaments, Wells Primary Porosity Primary Porosity, Wells Primary Porosity, Lineaments Primary Porosity, Lineaments, Wells Secondary Porosity Secondary Porosity, Wells Secondary Porosity, Lineaments Secondary Porosity, Lineaments, Wells km mi