Identifying Land Degradation and its Driving Factors in the Aral Sea Basin From 1982 to 2015

Abstract

Land degradation is one of the critical ecological issue in the Aral Sea Basin (ASB). This study investigates land degradation in ASB during 1982–2015 using the Normalized Difference Vegetation Index (NDVI) as a proxy. The residual trend (RESTREND) for temperature, precipitation, soil moisture adjusted NDVI has been applied to identify the land degradation in ASB and quantify the contribution of climate factors such as temperature and rainfall. In addition, a binary logistic regression model is adopted to assess the contributions of land transition, socio-economic, and topographical conditions on land degradation. Based on RESTREND, the relative contribution of precipitation (30.2%), soil moisture (23%), and temperature (11.4%) indicates that precipitation is one of the main driving factors of land degradation. The results further revealed that 36.5% of ASB is degraded, which is mostly concentrated in the lower part of the ASB. In contrast, 33.2% of ASB depicts land improvement, especially in the upper part of the basin. According to the land transition assessment, 66.6% of the water area and 11.68% of forest converted to barren land and shrubland during the study period, respectively. The binary logistic regression model demonstrated water and forest area transitions into shrubland and barren land as the major contributors of contemporary land degradation in ASB. Cropland recorded a net increment by 2.69% of its initial area, and the abandoned cropland converted to shrubland and barren lands that negatively impacted land cover change. This in-depth analysis of land degradation can assist in designing pragmatic policy interventions for implementing land restoration plans in the area.

Relationship between climate and land cover change in Aral Sea Basin

“…This article uses soil moisture data from the Global Land Data Assimilation System (GLDAS, https://disc.gsfc.nasa.gov). Its resolution is 0.25x0.25 degrees, and layer depth is 0-10 cm [18].…”

“…Dependency and intensity of vegetation change in function of temperature and precipitation are significant and vary among different land cover types [13,17]. Previous studies show the only relationship between annual vegetation change and climate factors in the territory of the Aral Sea, but do not account for seasonal changes separately [1,6,[18][19][20]. It is essential to investigate current and retrospective changes in different vegetation types in relation to seasonal climatic changes and anthropogenic activities in the Aral Sea Basin.…”

Apportioning Human-Induced and Climate-Induced Land Degradation: A Case of the Greater Sekhukhune District Municipality

“…There is an urgent need for an objective, measurable, repetitive, systematicand spatially and temporally explicit assessments of LD [30]. The long-term temporal and spatial reduction of vegetation productivity trend in drylands is regarded as an effective indicator of LD [31].…”

Spatio-Temporal Variations of Climate Variables and Extreme Indices over the Aral Sea Basin during 1960 - 2017

“…In this paper, we present the complex and detailed analysis that we performed by combining temporal and spatial changes in key climate parameters (temperature (TMP), precipitation (PRE) and potential evapotranspiration (PET) in the entire ASB and its sub-regions (Low part of ASB, Mid part of ASB and Upper part of ASB). So far, such a combined approach has been adopted only by a few studies [15,[20][21][22][23][24][25], and these studies are not focused on the ASB. Seasonal changes in temperature and precipitation patterns are the key parameters that provide the general overview of past climatic changes as far as this study region (i.e.…”