Evaluation of hydrologic impact of an irrigation curtailment program using Landsat satellite data

Abstract

Upper Klamath Lake (UKL) is the source of the Klamath River that flows through southern Oregon and northern California. The UKL Basin provides water for 81,000 + ha (200,000+ acres) of irrigation on the U.S. Bureau of Reclamation Klamath Project located downstream of the UKL Basin. Irrigated agriculture also occurs along the tributaries to UKL. During 2013-2016, water rights calls resulted in various levels of curtailment of irrigation diversions from the tributaries to UKL. However, information on the extent of curtailment, how much irrigation water was saved, and its impact on the UKL is unknown. In this study, we combined Landsat-based actual evapotranspiration (ETa) data obtained from the Operational Simplified Surface Energy Balance model with gridded precipitation and U.S. Geological Survey station discharge data to evaluate the hydrologic impact of the curtailment program. Analysis was performed for 2004, 2006, 2008-2010 (base years), and 2013-2016 (target years) over irrigated areas above UKL. Our results indicate that the savings from the curtailment program over the June to September time period were highest during 2013 and declined in each of the following years. The total on-field water savings was approximately 60 hm 3 in 2013 and 2014, 44 hm 3 in 2015, and 32 hm 3 in 2016(1 hm3 = 10,000 m 3 or 810.7 ac-ft). The instream water flow changes or extra water available were 92, 68, 45, and 26 hm 3 , respectively, for 2013, 2014, 2015, and 2016. Highest water savings came from pasture and wetlands. Alfalfa showed the most decline in water use among grain crops. The resulting extra water available from the curtailment contributed to a maximum of 19% of the lake inflows and 50% of the lake volume. The Landsat-based ETa and other remote sensing datasets used in this study can be used to monitor crop water use at the irrigation district scale and to quantify water savings as a result of land-water management changes.

A Review of Irrigation Information Retrievals from Space and Their Utility for Users

“…A first advance was to separate the identification of irrigated areas from general land cover classification approaches. A second advance came with improvements in spatial resolution, which allowed for more accurate assessments of irrigated areas [123,145] that do not hinge on information about the fraction of irrigated area within low-resolution pixels. A third advance was the synergetic use of various satellite, climatic, and ecoregions time series instead of vegetation index time series alone.…”

Riparian Area Changes in Greenness and Water Use on the Lower Colorado River in the USA from 2000 to 2020

“…These tasks include scheduling for irrigation; sustaining agricultural production; securing foods and safe water quality and quantity for human uses; managing watersheds; allocating water; determining water rights; forecasting weather; and monitoring, managing, and projecting the long-term effects of land use change and global climate change on water resources [1][2][3][4][5]. Remotely sensed ET maps are useful for negotiating interstate and international water agreements, determining allocations for mining, urban use or natural resources managed by the U.S. Department of Interior, tribes and citizens, and for estimating water use by natural vegetation which creates habitat and requires protections for native and by invasive species [6][7][8][9][10]. Remotely sensed ET studies are often focused on agricultural water needs in drylands and importantly assess the impact of drought on consumptive water use [11][12][13].…”

Satellite‐Based Monitoring of Irrigation Water Use: Assessing Measurement Errors and Their Implications for Agricultural Water Management Policy

“…Similar challenges also exist for surface water irrigation or conjunctive use of both groundwater and surface water. Time lags and spatial redistribution of return flows may alter short‐term availability of water for downstream users (Speir et al, 2016; Velpuri et al, 2020), with negative consequences where timing of water supply is important for these users, such as for freshwater ecosystems that are highly sensitive to intraseasonal flow dynamics (Stewart et al, 2020).…”