Lineament features were mapped in, visible bands from ASTER and DIP product derived from Landsat ETM+ Images as well as in a LiDAR (2m) DEM. Lineaments of geological origin were identified within the karstic areas and possibly are correlated to discharge areas. Several types of images are necessary to make a more accurate lineament mapping, there are features that appear in one type of image and that would not appear in another type. The spatial resolution of the image influences the ability to identify lineaments, especially in karst terrains. In addition, field verification, stable isotopes, rainfall will be analyzed to better understand the influence of fracturing and dissolution features on groundwater hydrology in the region. Because of the high vulnerability to transport contaminants karst aquifers possess, having a better understanding of topographic, hydrological and tectonic relations is crucial to address environmental issues. LINEAMENT MAPPING FOR GROUNDWATER EXPLORATION USING REMOTELY SENSED IMAGERY IN KARST TERRAINS Carla Alonso Contés, Miriam Rios-Sanchez, John S. Gierke Michigan Technological University, 1400 Townsend Drive, Houghton, MI REFERENCES Bruning, J.N A digital processing data compilation approach for using remotely sensed imagery to identify geological lineaments in hard-rock terrains: an application for groundwater exploration in Nicaragua, in Department of Geological/Mining Engineering & Sciences., Michigan Technological University: Houghton. Meijerink, A.M.J., and contributors Remote sensing applications to groundwater. IHP-VI series on groundwater; 16. Paris: UNESCO. 311 Olcott, P.G. U.S. Geological Survey GROUND WATER ATLAS of Puerto Rico and the U. S. Virgin Islands,1999, HA 730-N. Bawiec, Walter J., 1998, Geology, geochemistry, geophysics, mineral occurrences, and mineral resource assessment for the commonwealth of Puerto Rico: Open-File Report 98-38, Geological Survey (U.S.). Lugo A.E., Miranda Castro, L., Vale, A., del Mar López, T., Hernández Prieto, E., García Martinó, A., Puente Rolón, A.R., Tossas, A.G., McFarlane, D.A., Miller, T, Rodríguez, A., Lundberg, J., Thomlinson, J., Colón, J., Schellekens, J.H., Ramos, O., Helmer, E., 2001, Puerto Rican Karst, A Vital Resource, General Technical Report WO-65, U. S. Department of Agriculture Forest Service Gen. Tech. Renken, R. A., Ward, W.C., Gill, I.P., Gomez-Gomez, F., Rodriguez-Martinez, J., and others., 2002, Geology and hydrogeology of the Caribbean islands aquifer system of the commonwealth of Puerto Rico and the U.S. Virgin Islands: U.S. Geological Survey Professional Paper 1419, 139 p Giusti, E.V., 1978, Hydrogeology of the Karst of Puerto Rico: USGS Prof. Paper 1012, 65 p. Alemán González, W.B., comp., 2010, Karst map of Puerto Rico: U.S. Geological Survey Open-File Report 2010–1104, 1 map sheet, scale 1:140,000, available online at Kresic N., 1995, Remote Sensing of Tectonic Fabric Controlling Groundwater Flow in Dinaric Karst, Remote Sensing of the Environment Volume 53, p Meijerink, A. M. J. (1996). "Remote Sensing Applications to hydrology: groundwater." Hydrological Sciences Journal 41(4): ACKNOWLEDGEMENTS - My Co-authors, Mike Falkowski, Tom Miller, Simon Carn. -This research is supported by the US National Science Foundation through OISE and PIRE Global Landcover Facility (Landsat Images and Digital Elevation Models DEM) -LP DAAC. NASA Land Processes distributed active archive center (ASTER Images). -Alaska Satellite Facility (Radarsat Images). -USGS Global Visualization Viewer.(Landsat ETM+/MRLC 2001 and Hyperion) For this study we are interested in using remotely sensed imagery with different spectral (Figure 5), spatial and radiometric resolutions. Original images used include: Landsat ETM+ MRLC (30 m) and the band 8 (15m), ASTER visible bands (15 m), LiDAR DEM (2m) and a RADARSAT image with ascending (~ 15 m) and descending orbits (~50m). The use of different types of imagery lets us see features of different origin on earth surface. Some of other products derived in ERDAS imagine for this study are shown in Figure 6. Features we are interested in are lineaments, which for this study can be define as a linear feature corresponding to faulting, fracturing, geomorphology or vegetation trends. These features might be indicators of the solubility of the rock and can be associated with cavern/fissure conduits. Mapping regional faults that can be associated with zones of high permeability and concentrated groundwater flow Meijerink (2007). TASKS TO COMPLETE Puerto Rico is located in the Caribbean Sea, South East of the Southern Florida Coast. The area of study is the Tanamá river catchment located on the North western part of the island (Figure 1) on the Northern Coast Karst (NCK) belt. The NCK Basin of Puerto Rico accounts for 22 % of freshwater withdrawals, also contributes to base flow for surface water bodies Lugo et al (2001) and is a habitat for wide variety of flora and fauna. Due to its rough terrain there is little rural development. Nevertheless is still very vulnerable to deforestation, surface and groundwater contamination and aquifer over-use which can lead to other issues like salt water intrusion and subsidence. Figure 1: Location map of the Tanamá River Catchment enclosed in red. Area in orange represents the NCK belt extent digitized from Alemán González (2010) and a Landsat ETM MRCL 2001 image. Geology/Hydrology In the NCK the rock was deposited over volcanic sediment, in shallow water areas Giusti (1978). This regions has two separate aquifers, confined and unconfined. The NCK tertiary basin has 2000 m of accumulated carbonate and siliclastic sedimentary rock from the Oligocene and Pliocene Renken et al (2002), that dips north and strikes east west. This causes the ground water to flow down dip along the more permeable bedding layers Giusti (1978). The limestone formations that comprise the Tanamá basin are shown in Figure 2. The NCK is a series of mogotes (cone karst) Figure 3, underlain by a network of cavities which The rainy season occurs in June through November. Recharge in karst areas is mostly characterized by discrete infiltration through karstic features as sinkholes that might occurs along faults Kresic (1995), intermittent streams and rivers. Nevertheless, faulting has not been reported or mapped in the NCK belt due to the rugged nature of the terrain (Figure 4). Figure 3: Photo by J. Alonso of a Mogote hill behind the Arecibo Observatory Figure 4: Shuttle Radar Topographic Mission (STRM) Digital Elevation Model (DEM) 30 m spatial resolution of the island overlain by faults from Bawiec (1998). Figure 6: From L to R IHS and the NDVI of the Landsat ETM+ Figure 8: Landsat ETM+ MRLC 2001 bands 421 showing the extent of the area. Figure 12: a) Aster image bands 123. b) Aster 321 Differential dissolution Fault After visual interpretation and mapping of lineaments is complete in ArcGIS 9.3 the following will be completed: a) Coincidence analysis of lineaments; A lineament shall be considered coincident if it falls within a buffer zone of another Bruning (2008). For this all interpretations from images and another interpreter’s results will be taken into account. b) Lineament density per area calculations c) Directional trend of lineaments d) Determine if the lineament analysis results correlate to existing hydro-geological features affecting GW flow. Figure 13: a) Landsat ETM+ Band 8 with spring and sinkholes grater than 30 m deep locations (from Aleman,2010) b) Preliminary lineament map GSA Annual Meeting Poster # 146 Another type of lineaments present is those caused by differential erosion of dipping strata (Figure 12a&b). Such features can influence on groundwater flow. How is this influence is manifested might be shown in further analysis once the lineament analysis is done analysis of the correlation between lineament location, sinkhole location and spring location (Figure 13a ) will be completed as well as correlations between lineaments and stable isotopes from field proofing data. A preliminarily lineament map is shown (Figure 13b) to qualitatively analyze the correlation of sinks greater than 30 m deep to lineament distribution and directional trend. Lineament mapping and careful delineation of the karstic terrain extent in karstic formations can help to understand its flow systems. AO Photo by J. Alonso CONCLUSIONS Atlantic Ocean Caribbean Sea Northern Karst belt BACKGROUND LINEAMENT MAPPING Area of Study Figure 2: Geologic map of the Tanamá Basin. Modified from: Olcott (1999). Limestone: Ta, Tay, Tcb, Tcbm, Tcm,Tla, Ts. Figure 10: Photo showing cone and doline karst terrain in the Arecibo area. AO Spring Figure 9: LiDAR DEM lineaments correlated to springs. Figure 7: LiDAR DEM showing lineaments and the AO sinkhole. Figure 11: Aerial photography taken by NASA in 1990 of top view of the Arecibo Observatory (AO) b a Bruning (2008) mapped lineaments using remotely sensed imagery by identifying patterns based on color, tone, and texture in a volcanic region. Using the imagery mentioned before lineaments of different origin were mapped. Examples are shown in figures Such lineaments have possible influences on known springs (Figure 9) and the sinkholes specifically the Arecibo Observatory (AO) radio telescope sinkhole (Figure 7). The AO is located on the side of the Tanamá river course. The Tanamá basin is filled with much more sinkholes and mogotes (Figure 10 & 11) that might be influenced by lineaments. Correlation needs to be done with the regional structural geology to determine the relationships to the lineaments. NDWI can be used to evaluate the potential of those lineaments as recharge or discharge areas. LOCATION a b REMOTELY SENSED IMAGERY Figure 5: Spectral resolutions of different sensors. Adapted from: RADARSAT International Radarsat Geology Handbook. Richmond, B.C. Landsat ASTER RADARSAT