Use of remote sensing Landsat-EVI in the assessment of landscape degradation (On the example of the Aydar-Arnasay lake systems)

¹ Department of Geography and Ecology, Samarkand State University named after Sharaf Rashidov, 140104, Samarkand, Uzbekistan
² Faculty of Geography, Philipps-Universität Marburg, Germany

^* Corresponding author: nilufar.samsu@gmail.com

Abstract

The Arnasay depression in Central Uzbekistan received large quantities of drainage water leading to the formation of the Aydarkul-Arnasay Lake System (AALS). The water level of the AALS drastically increased in 1969, when a flood in the nearby Syrdarya River basin could not be contained in the Chardarya reservoir, and today it occupies an area of 4000 km² of the Mirzachul and Kyzylkum desert. Increasing the lake’s water level also affects the surrounding agricultural land, further enhancing the level of groundwater and soil salinization. But the irrigated farming areas also influence the lake system due to the pollution of the drainage water discharged into the lake. As a result, both the arable land and the lake system are in a process of degradation, leading to reduced productivity and a variety of ecological problems. Remote sensing was used to determine the degradation process in agroirrigation landscapes around the lake. Landsat EVI (Enhanced vegetation index) extremely resistant to various atmospheric resistances (aerosols). It monitors plants with very high sensitivity even in low biomass areas. Landsat EVI images were compared in March-April, May-June, June-July, July-August, and August-September to classify the degradation process in the agroirrigation landscapes around the lake. Landsat has 4,5,7,8 series programs. In the article used Landsat-5TM Collection 1 Tier 1 32-Day EVI and Landsat-8 ETM + Collection 1 Tier 32-Day EVI. In Landsat EVI, July-August was chosen as the optimal time to detect agroirrigation landscape degradation. Classifications of agroirrigation landscape degradation have been developed at Landsat EVI.