Methods

   Landsat 5 imagery was used to analyze the Ventura County study area in August of 1997, 2009, and 2011. The year 1997 was used as a “baseline” for vegetation in this study, as it is primarily concerned with recent drilling since 2011. Imagery from August were used to avoid cloud contamination in the imagery and to provide a standard for summer vegetation. Images from 2009 were used to provide a visualization of vegetation change before the recent increase in drilling.

   Using the USGS Global Visualization Viewer (GLOVIS), LandSat 5 imagery of Ventura County (path 41, row 36) was downloaded. Imagery was then modified and analyzed using ENVI remote sensing software to create Normalized Difference Vegetation Indices (NDVI), thermal imagery, and change detections.

   The Normalized Difference Vegetation Index (NDVI) is a graphical indication of vegetation density from -1 (water) to 1 (temperate and tropical rainforests). This NDVI was made using the visible red (band 3, .63-.69 µm) and near infrared (band 4, .76-.90 µm) bands on the Landsat 5’s Thematic Mapper (TM) sensor. A value of zero represents a neutral area consisting of rock, sand or snow.  This NDVI is mapped out on a graduated color scale between a series of hues representing the index.  The study’s analysis uses a blue to white NDVI scale, where negative values are represented by darker hues and therefore less vegetation, while light hues represent high indices and high vegetation.

   Thermal images were gathered by analyzing TM’s band 6. These images were modified using ENVI in an orange to white gradient, with white representing highest temperatures. Change detections were done on both the NDVIs and thermal imagery to show changes in vegetation and temperature correlated with drilling. Analysis in ArcGIS was also done to illustrate the geographic locations of each hydraulically fractured well in the study area. Data was provided by the California Department of Conservation. This analysis was exported into raster form and placed back into ENVI.