Investigating the causes of Lake Urmia shrinkage: climate change or anthropogenic factors?
Received date: 2022-08-12
Revised date: 2022-11-21
Accepted date: 2022-12-14
Online published: 2023-04-30
In the current scenario, Lake Urmia, one of the vastest hyper saline lakes on the Earth, has been affected by serious environmental degradation. Using different satellite images and observational data, this study investigated the changes in the lake for the period 1970-2020 based on the effects of climate change and several human-induced processes on Lake Urmia, such as population growth, excessive dam construction, low irrigation water use efficiency, poor water resources management, increased sediment flow into the lake, and lack of political and legal frameworks. The results indicated that between 1970 and 1997, the process of change in Lake Urmia was slow; however; the shrinkage was faster between 1998 and 2018, with about 30.00% of the lake area disappearing. As per the findings, anthropogenic factors had a much greater impact on Lake Urmia than climate change and prolonged drought; the mismanagement of water consumption in the agricultural sector and surface and underground water withdrawals in the basin have resulted in a sharp decrease in the lake's surface. These challenges have serious implications for water resources management in Lake Urmia Basin. Therefore, we provided a comprehensive overview of anthropogenic factors on the changes in Lake Urmia along with existing opportunities for better water resources management in Lake Urmia Basin. This study serves as a guideline framework for climate scientists and hydrologists in order to assess the effects of different factors on lake water resources and for decision-makers to formulate strategies and plans according to the management task.
Mehri SHAMS GHAHFAROKHI , Sogol MORADIAN . Investigating the causes of Lake Urmia shrinkage: climate change or anthropogenic factors?[J]. Journal of Arid Land, 2023 , 15(4) : 424 -438 . DOI: 10.1007/s40333-023-0054-z
Fig. 1 Overview of Lake Urmia Basin (a) and satellite images showing the variations of the area of Lake Urmia in 1984 (b), 1998 (c), 2007 (d), 2014 (e), and 2018 (f). Note that the images were acquired by Landsat 5, 7, and 8. |
Table 1 Detailed information of Lake Urmia |
Item | Description |
---|---|
Geographical location | Coordinates of 44°13′-47°54′E and 35°40′-38°29′N in Iran. |
Surface area | 3500 km2 in 2013 (maximum length of 140 km and maximum width of 55 km). |
Depth | Average depth: 6 m; maximum depth: 16 m. |
Lake level | Ecological level of the lake's water level: 1274.1 m a.s.l. |
Permanent main water sources | (1) Aji Chai; (2) Alamlou River; (3) Barandooz River; (4) Gadar River; (5) Ghaie River; (6) Leilan River; (7) Mahabad River; (8) Nazloo River; (9) Roze River; (10) Shahar River; (11) Simine River; (12) Zarrine River; (13) Zola River. |
Table 2 Indicators used to estimate the area of Lake Urmia |
Indicator | Formula | Reference |
---|---|---|
Automated water extraction index (AWEI) | $\text{AWEI}=4({{X}_{\text{Green}}}-{{X}_{\text{MIR}}})-(0.25{{X}_{\text{NIR}}}+2.75{{X}_{\text{SWIR}}})$ | Feyisa et al. (2014) |
Automated water extraction index (shadow correction; AWEIsh) | $\mathrm{DVW}=\frac{X_{\mathrm{NIR}}-X_{\mathrm{Red}}}{X_{\mathrm{NIR}}+X_{\mathrm{Red}}}-\frac{X_{\mathrm{NIR}}-X_{\mathrm{MIR}}}{X_{\mathrm{NIR}}+X_{\mathrm{MIR}}}$ | Acharya et al. (2018); Wang et al. (2018) |
Difference between vegetation and water (DVW) | $\text{DVW}=\frac{{{X}_{\text{NIR}}}-{{X}_{\text{Red}}}}{{{X}_{\text{NIR}}}+{{X}_{\text{Red}}}}-\frac\\ {{{X}_{\text{NIR}}}-{{X}_{\text{MIR}}}}{{{X}_{\text{NIR}}}+{{X}_{\text{MIR}}}}$ | Lyon et al. (1998); Xu et al. (2013); Naji (2018) |
Modified normalized difference water index (MNDWI) | $\text{MNDWI}=\frac{{{X}_{\text{Green}}}-{{X}_{\text{MIR}}}}{{{X}_{\text{Green}}}+{{X}_{\text{MIR}}}}$ | Xu (2005) |
Normalized difference vegetation index (NDVI) | $\text{NDVI}=\frac{{{X}_{\text{NIR}}}-{{X}_{\text{Red}}}}{{{X}_{\text{NIR}}}+{{X}_{\text{Red}}}}$ | Pettorelli (2013) |
Normalized difference water index (NDWI) | $\text{NDWI}=\frac{{{X}_{\text{Green}}}-{{X}_{\text{NIR}}}}{{{X}_{\text{Green}}}+{{X}_{\text{NIR}}}}$ | Gao (1996); McFeeters (2013) |
Note: XGreen, green wavelength (nm); XMIR, mid-infrared wavelength (nm); XNIR, near-infrared wavelength (nm); XSWIR short-wave infrared wavelength (nm); XRed, red wavelength (nm). |
Fig. 2 Behavior of a system in response to disturbances: recovery from disturbances to normal state |
Table 3 Area of Lake Urmia in 2014 calculated from different indicators |
Index | Water pixels (%) | Area (km2) | Absolute error (km2) |
---|---|---|---|
AWEI | 6.94 | 2457.93 | 457.93 |
AWEIsh | 69.54 | 24,637.89 | 22,637.89 |
DVW | 16.11 | 5708.99 | 3708.99 |
MNDWI | 15.11 | 5354.68 | 3354.68 |
NDVI | 37.03 | 13,120.57 | 11,120.57 |
NDWI | 6.19 | 2193.38 | 193.38 |
Fig. 3 Changes in the total area of Lake Urmia during 1970-2020 based on normalized difference water index (NDWI) |
Fig. 4 Changes in the total water volume of Lake Urmia and precipitation of Lake Urmia Basin during 1970-2020 |
Fig. 5 Chnages of the average standardized precipitation index (SPI) in Lake Urmia Basin during 1970-2020. Negative red SPI indicates the occurrence of drought and positive blue SPI means the end of drought. |
Fig. 6 Changes in the total water volume of Lake Urmia and population of Lake Urmia Basin during 1970-2020 |
Fig. 7 Changes in the total water volume of Lake Urmia and agricultural water use of Lake Urmia Basin during 1970-2020 |
Fig. 8 Changes in the total water volume of Lake Urmia and surface water withdrawals of Lake Urmia Basin during 1970-2020 |
Table 4 Comparing the observed water volume of Lake Urmia and modelled water volume from the Water Evaluation and Planning System (WEAP) during 2011-2018 |
Data | Water volume (×109 m3) | |||||||
---|---|---|---|---|---|---|---|---|
2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | |
Observed data | 3.16 | 2.49 | 1.87 | 1.48 | 1.90 | 1.95 | 1.54 | 1.66 |
WEAP modelling data | 3.66 | 3.20 | 2.49 | 2.09 | 1.84 | 1.72 | 1.71 | 1.65 |
Table 5 Comparing the observed water demand of Lake Urmia Basin and modelled water demand from the WEAP in different sectors in 2018 |
Data | Water demand (×109 m3) | ||
---|---|---|---|
Domestic sector | Agricultural sector | Industrial sector | |
Observed data | 175.90 | 3351.10 | 97.10 |
WEAP modelling data | 189.90 | 3236.30 | 69.95 |
Fig. 9 Observed total water volume of Lake Urmia during 2000-2020 and modelled water volume from the WEAP during 2020-2040 based on the different adopted management strategies. S1, the basic strategy; S2, a 25.00% decrease in water demand in the industrial and domestic sectors; S3, a 40.00% decrease in water demand in the agricultural sector; S4, water transferring to Lake Urmia; S5, a 25.00% reduction in all water demands. |
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