Water Department
The Owens Valley Monitor 1999-2000
| Air Photo Study As part of the EIR for the Inyo/Los Angeles Water Agreement, and the Memorandum of Understanding that resolved concerns over the adequacy of the EIR, the county and LADWP agreed to conduct an evaluation of existing air photos of the Owens Valley and to consider how to use air photos or other forms of remote sensing in future management. In December 1998, Ecosat Geobotanical Surveys, Inc., was hired to carry out the first phase of this important Inyo/Los Angeles cooperative study. Ecosat's tasks are to:
The study is to be conducted in two phases. The first phase involves testing air photo interpretation techniques by evaluating existing air photos of certain areas of the valley. The second phase will be the expansion of the evaluation to other areas of the valley. Ecosat's first tasks were to request, locate, then acquire all the materials, data, and reports necessary to accomplish the study. This entailed examining existing aerial photo sets from 1944, 1968, 1981, and 1996 and satellite imagery from 1973. In the course of the examination, they determined that the 1981 photos should be re-printed from negatives, so this was done. They also reported that the 1968 photographs were of poor quality, but the negatives could not be found for re-printing. Unfortunately, Ecosat will not be able to analyze these photos to the same level as the photo sets for the other years. Ecosat worked with ICWD and LADWP to define the "Phase 1" study areas. During Phase 1 of the aerial photo study, efforts were to be focused on key areas that include a broad range of vegetation types present in the valley. Five areas around Laws, Big Pine, Hines Spring, Blackrock Fish Hatchery, and Independence were identified, totaling approximately 15,000 acres. Ecosat then delineated polygons, or units, of relatively homogenous vegetation and traced these polygons onto scanned images of the 1981 aerial photos. The result was a more detailed baseline vegetation map than is currently used by ICWD and LADWP. Next, using existing ICWD vegetation data and data collected during Ecosat's field visits to the valley, Ecosat developed a classification scheme for Owens Valley's vegetation. The plant community types that resulted from this analysis will serve as the legend for attributing the new map of baseline vegetation conditions. Currently, Ecosat has turned its attention to attempting to identify vegetation changes from the aerial photographs from 1944 through 1996. For this task, Ecosat needs information on land use and hydrology, such as fire, water spreading, wildlife and livestock usage areas. ICWD and LADWP are working to assemble those data. Ecosat is also preparing for its accuracy analysis of the interpretations of the aerial photo sets. This necessary step estimates the accuracy level of the features the interpreters identify. The first phase of the aerial photography study will be completed during 2000. After reviewing the results of the study, Inyo County and Los Angeles will decide whether to proceed to phase two of the study. In Phase 2, the aerial photo study tasks would be performed for the entire Owens Valley. Return to the Table of Contents  |