A Geographical Survey of Center Pivot Irrigation Systems in the Central and Southern High Plains Aquifer Region of the United States

HighlightsAll center pivot irrigation systems in the Central and Southern High Plains Aquifer region were digitized.Out of 2.76 Mha under center pivots, the largest portion (58%) was in Texas and the smallest (2%) in Colorado.Most center pivots were about 50 ha, with a range of 1 to >230 ha.The new layer can be used in extracting distributed soil, weather, and crop data for various precision agriculture applications.Abstract. With the declines in water levels of the Central and Southern High Plains Aquifer, there is a critical need to accurately map the irrigated agriculture in this region as it is the largest user of groundwater resources. The goal of this study was to develop a geospatial database of all areas under the most dominant irrigation system in the region: center pivots. The borders of all center pivots (50,116) were manually digitized using high spatial resolution satellite imagery, delineating the area that can be potentially irrigated by these systems. Most center pivots were comparable in size (ca. 50 ha), with a range of 1 to >230 ha. The areas of digitized center pivots at the state and study area levels were relatively close to estimates of two actual irrigated area products based on automatic land classification. The new layer was also used to extract available data on groundwater level changes since predevelopment (before 1950). Aquifer regions under center pivots in Colorado and Texas had the smallest and largest declines in water level, respectively. The new layer offers advantages in terms of accurately identifying the area covered by center pivots and has potential research and practical applications such as studying adopted practices in response to water level declines, assessing field-scale irrigation uniformity, and extracting distributed soil, weather, and crop data to be used in various precision agriculture applications. The new layer is freely available to the public as supplemental information of this article (https://doi.org/10.13031/14707284). Keywords: Groundwater decline, Irrigated fields, Ogallala, Sprinkler irrigation.

High Plains Aquifer–State of Affairs of Irrigated Agriculture and Role of Irrigation in the Sustainability Paradigm

Groundwater depletion is a serious issue in the southern and central parts of the High Plains Aquifer (HPA), USA. A considerable imbalance exists between the recharge process and groundwater extractions in these areas, which threatens the long-term sustainability of the aquifer. Irrigated agriculture has a major share in the economy, and it requires high pumping rates in regions vulnerable to large groundwater level declines. A literature review has been conducted to understand the state of affairs of irrigated agriculture in the HPA, along with the dynamics of groundwater decline and recharge using statistical and remote-sensing based datasets. Also, three irrigation management and technology-based approaches have been discussed from the perspective of sustainability. The southern and central parts of the HPA consist mostly of non-renewable groundwater formations, and the natural water storage is prone to exhaustion. Moreover, the aforementioned regions have comparatively higher crop water requirement due to the climate, and irrigating crops in these regions puts stringent pressure on the aquifer. The upper threshold of irrigation application efficiency (IAE) is high in the HPA, and could reach up to 95%; however, considerable room for improvement in irrigation water management exists. In general, the practices of irrigation scheduling used in the HPA are conventional and a small proportion of growers use modern methods to decide about irrigation timing. Among numerous ways to promote sustainable groundwater use in the HPA, deficit irrigation, use of soil moisture sensors, and subsurface drip irrigation can be considered as potential ways to attain higher lifespans in susceptible parts of the aquifer.