Every ten years, the Colorado Springs Utilities (CSU) is required by the State Water Resources Board to report the amount of irrigated land within its Water Service Area. Faced with the rapidly approaching deadline, CSU recently found an accurate and effective solution using GIS software. Using the Normalized Difference Vegetation Index (NDVI), Vegetation Analysis tool grouped pixels into VEG (high infrared value) or NON (little or no infrared value). The approach that fit the desired criterion was to utilize color infrared photography (“CIR”) and automated data analysis capabilities provided by existing software. The calculated amount of irrigated land will be correlated to the number of equivalent taps in use within the Water Service Area, and that determination will be used in the annual non-sewered Return Flow Accounting Report. The correlation is used to determine the amount of non-sewered return flow water that Colorado Springs can claim, capture, and reuse under the State Water Rights Decree.
Aerial photography of 145 square miles of CSU’s service area was completed in the Fall. The Vegetation Analysis software offers powerful alternatives to the data classification methods. Using this tool, imagery returns can be classified into vegetative and non-vegetative groups. This process classifies data into groups based on the value of pixel color. Classification routines are used to group pixels into classes based on their color. CSU completed a major project from design to implementation to final conclusions making full use of the power of GIS and automated data processing.