Mapping On-Farm Irrigation Systems In Southern Idaho

About half (or $106.3 billion in 2012) of the market value of crops sold in the United States is produced on irrigated farms with the vast majority (71%) of these farms located in the 17 western states. Irrigation water whether sourced from surface or subsurface water resources is applied to these agricultural fields using a variety of systems categorized in three broad groups: gravity irrigation, microirrigation and sprinkler irrigation. In the 82,000 ha Twin Falls Canal Company irrigation in south central Idaho, two major types of irrigation systems are used: sprinkler and furrow irrigation. Concerns over high rates of sediment and nutrient loads to the Snake River with the historically used furrow irrigation system led to increased adoption of various forms of sprinkler irrigation systems. For an accurate assessment of the impact of changes in irrigation systems on soil and water resources in the watershed over time, data on the spatial extent and distribution of the various types and forms of irrigation systems are needed. Such spatial data currently do not exist and are difficult to assume considering the highly dynamic adoption rate of new irrigation systems in the watershed. This study aims to apply advances in pattern recognition and machine learning to publicly available remote sensing datasets to identify and survey irrigation systems in agricultural fields across the watershed. With this new methodology, past and future changes in irrigation systems can be related to water quality dynamics from available irrigation return flow monitoring sites across the watershed. The developed technique can be generalized to other watersheds where sprinkler and surface irrigation methods are both used.