William C. Draeger 1976 <p>A demonstration of the utility of Landsat imagery for quickly and cheaply estimating irrigated land area was conducted in the Klamath River basin of Oregon. Landsat color composite images, at 1:250,000 scale and acquired on two dates during the 1975 growing season, were interpreted. Irrigated lands were delineated manually, and the irrigated area was estimated, based on dot-grid sampling of the manually delineated lands. The image interpretation estimate of irrigated area was then adjusted by a comparison of interpretation results with ground data on 45 sample plots, each 1 mi² (2.6 km²) in size.</p><p>Two interpreters independently estimated the irrigated area. &nbsp;Their adjusted estimates were 285,000 acres (115,000 ha) and 267,000 acres (108,000 ha) respectively, with corresponding 95 percent confidence intervals of ±19,500 acres (7,880 ha) and ±34,700 acres (14,000 ha). The estimated cost of the survey, exclusive of management costs and training, was $1,500.</p> application/pdf 10.3133/ofr76630 en U.S. Geological Survey Monitoring irrigated land acreage using Landsat imagery: an application example reports