Analysis of decadal land cover changes and salinization in Urmia Lake Basin using remote sensing techniques

Abstract

Abstract. Urmia Lake located in the north-west of Iran, is one of the largest hyper-saline lakes in the world. In recent years, most of the Urmia Lake have been rendered to unusable lands. Drought and rapid increase in agricultural activities are the most important reasons behind the shrinkage of the Lake. This kind of exploitation with the added salinity from irrigation occurring over time has caused increased soil salinity in the basin leading up to desertification. Soil salinity research are crucial to understand underlying causes and consequences of the drying Urmia Lake. In this study, we use remote sensing technology and image processing techniques to detect spatio-temporal variability of salt body, salt affected lands, and development of irrigated lands to estimate the extend of salinization in terms of spectral response of satellite images for the Urmia Lake Basin from 1975 to 2016. The results of this study indicate that salt and salty soil areas has increased dramatically from 1995 to 2014 and more than 5000 km2 of Urmia Lake's water surface area was converted to salt or salty soil bodies during recent years. Salinization and desertification progress are not limited to just dried bottom of the Urmia Lake. Although the area of irrigated lands has increased more than two times during the studied period, soil salinity has increased in regions close to Urmia Lake too. This desertification in the basin have potential to be the source of dust storms, which have adverse effects on people's life and climate as well.

Is There a Relationship between Lake Urmia Saline Lakebed Emissions and Wet Deposition Composition in the Caucasus Region?

“…For context, the north part of Lake Urmia is fed by the Aji-Chay River, which is the most saline river in the basin . Dried lakebed areas around the body of Lake Urmia (i.e., Gulmankhaneh, Salmas, Aghdash, Agh Gonbad, and Bari stations) and the middle of the lake (i.e., Ashk Island station) exhibit elevated soil salinity indices, , and thus, it is hypothesized that the region’s emissions have influence from salts that decrease with distance from Lake Urmia’s shoreline. Relationships between ion concentration and distance from Lake Urmia are summarized in Figure S1, showing a decreasing gradient from high to low concentrations of salt and crustal ions as a function of distance away from the lake shoreline.…”

“…middle of the lake (i.e., Ashk Island station) exhibit elevated soil salinity indices,55,56 and thus, it is hypothesized that the region's emissions have influence from salts that decrease with distance from Lake Urmia's shoreline. Relationships between ion concentration and distance from Lake Urmia are summarized in FigureS1, showing a decreasing gradient from high to low concentrations of salt and crustal ions as a function of distance away from the lake shoreline.…”

Groundwater saving and quality improvement by reducing water footprints of crops to benchmarks levels

“…Agriculture is by far the largest water user: 97% of the total net blue water abstraction in Iran relates to irrigated crop production . The impact of the inefficient agriculture becomes visible through the partial disappearance of lakes, like Urmia Lake ( Ghale et al, 2017 ), the drying up of rivers, like the Zayandehroud River ( Madani, 2014 ), falling groundwater tables ( Rahnema and Mirassi, 2014 ), pollution of water ( Karandish et al, 2017a ), and damage to ecosystems and local livelihoods ( Madani, 2014 ). Moreover, inefficient water use leads to the loss of potential economic benefits that could be derived from increased yields.…”

Why is Lake Urmia Drying up? Prognostic Modeling With Land-Use Data and Artificial Neural Network

“…The lake provides important cultural, economic, aesthetic, recreational and scientific values (Abbaspour et al, 2012;Ahmadi et al, 2016). The lake area has decreased by 90% in recent decades (Pengra, 2012;AghaKouchak et al, 2015;Ghale et al, 2017;Mardi et al, 2018). The lake has been threatened by multiple anthropogenic activities, including increased agricultural activity, urban expansion, extensive construction of dams and anthropogenic changes to the lake system including a constructed causeway as well as severe climate change-induced droughts (Tourian et al, 2015;Alborzi et al, 2018).…”