Remote Sensing Projects

Evaluation of Irrigated Acreages 

INTERA assessed the accuracy of a remote-sensing based method of determining irrigated acreage over large areas using a methodology developed by the New Mexico Interstate Stream Commission.  The project used a combination of satellite imagery (Landsat) and on-the-ground fieldwork to assess the accuracy of the remote-sensing method over an area consisting of approximately 100,000 irrigated acres.  INTERA collected crop type and phenology (growth stage) information contemporaneously with acquisition of Landsat satellite imagery for approximately 100 target fields.  Data was collected for a total of three time periods: early-season, mid-season, and late-season.  Field data were collected using real-time GPS and GIS for field positioning.  Satellite imagery was analyzed to develop a vegetation index that allowed identification of irrigated areas. 

An assessment of the vegetation index was performed using the field-collected data to evaluate the accuracy of the remote-sensing based method.  Additional outcomes of the project included refinement of the remote-sensing based methodology and development of guidelines for application throughout New Mexico for use by a variety of water managers for more efficient and effective water management statewide.

Analysis of Surface Water Depletions

INTERA was retained by a confidential client to analyze potential historical changes in depletions from irrigated agriculture and riparian areas for a major stream system using GIS and remote sensing techniques.  The study area encompasses approximately 400,000 acres, and this analysis was the first historical regional analysis of its kind.  The data were used to evaluate potential changes in depletions from the stream system based on historical patterns in both irrigated acreages as well as temporal variations in riparian areas.  The data were used to evaluate temporal trends (if any) in stream system depletions as well as provide firm estimates of historical and present-day irrigated acreages throughout the region for use in developing surface-water models and other quantitative water management tools.  We also performed land-cover classification analyses using both supervised and unsupervised classification methodologies using Landsat remote sensing imagery to quantify irrigated acreages over a broad regional area.

Vegetation Index Analysis

INTERA successfully applied a normalized difference vegetation index (NDVI)-based approach to identify and quantify irrigated acreages in an arid southwestern area.  The NDVI-based approach was applied to determine irrigated acreages over three seasons and compared favorably with other published results.  Our efforts included the acquisition of appropriate Landsat 5 data for three periods during two active growing seasons (2003 and 2004), integrating the Landsat imagery into a regional GIS, and performing an NDVI-based analysis to determine irrigated acreage for each of the three periods, while filtering out riparian areas so that an accurate assessment of irrigated acreage could be performed.  The final products from the project included a full GIS of the study area including Landsat imagery and a final report summarizing our findings and conclusions.  The primary benefit realized by the client from the project was that the results of this project provided an independent quantification of irrigated acreage in the study area.