Satellite monitoring of winter irrigation activity in South Kazakhstan: A case study of Golognaya Step irrigated region; [Спутниковый мониторинг зимней промывки пашни от вторичного засоления на примере ирригационного массива «Голодная степь» (Южный Казахстан)]

The Kazakh part of a large irrigated area called Golodnaya Step is located in the Syr Darya River basin on the state border with Uzbekistan. In this region, the cheapest agricultural practice of furrow irrigation is used. This agrotechnology uses a significant amount of irrigation water, which causes a rise of saline groundwater level and activates the processes of secondary soil salinization. The regional approach of washing the saline soils on irrigated land is a procedure of winter irrigation. During winter irrigation, water mirrors are formed. Mirrors can exist for up to several months. The higher soil salinity, the more washing water it is recommended to use during winter irrigation. Satellite registration of the January-February water mirrors allows us to quantitatively characterize the procedure of washing soil salinity. In this research, the Landsat-8, -9 and Sentinel-1, -2 archives for the period January-February 2017-2022 were analyzed using Google Earth Engine. Seasonal January-February water mirror masks were created, average long-term conditions and seasonal deviations from them were calculated. Maps of deviations from the average long-term condition represent important information about the seasonal farming activity of soil salinity washing. Long-term average estimates of winter irrigation activity characterize the average long-term level of secondary soil salinity in the region. These research results may be of interest as a separate component of soil salinity monitoring, as well as for planning improvements to the regional irrigation and drainage infrastructure. © 2023 Space Research Institute of the Russian Academy of Sciences. All rights reserved.