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In this study, the extreme shrinkage of Urmia Lake is investigated, aiming to assess the impact of anthropogenic factors, particularly the over-construction of dams and natural anomalies associated with climate change. Historically available multispectral spatial data obtained from Landsat missions 4-5 TM and Landsat 8 OLI were utilized which totally covers a period of 36 years (1967–2020). Additionally, this data was employed to identify the locations of constructed water reservoirs and determine their construction timelines by analyzing the normalized difference vegetation index (NDVI). To examine the temporal patterns of annual precipitation in the lake basin, we obtained time series data from historical precipitation records, which were then converted into rasterized format. Our findings indicate that approximately 22% of the lake basin has been designated for feeding dam reservoirs. The impact of precipitation anomalies on the lake’s water level was found to be relatively less significant when compared to the increased storage capacity of the dams. Furthermore, the construction of dams prior to 2000 contributed to enhancing the lake’s stability during periods of drought. However, the substantial increase in the total storage capacity of dams after 2000 has significantly accelerated the shrinkage process. As a result, it was concluded that any effective rescue plan should prioritize ignoring a considerable portion of the reservoirs’ storage capacity by releasing stored water, thereby allowing the lake to attain a stable condition. [ABSTRACT FROM AUTHOR]

The arid region of Mongolia is sensitive to climate change. Understanding of climate variations in the past plays an important role in predicting further climate changes. In this study, we aim to investigate the relationship between the climatic factor and sedimentation history in the late Holocene. We analyzed the 18TS1 core sample (136 cm in length) from the Tsagaan lake in the Valley of the Gobi Lakes, Mongolia. The sediment core mainly consists of clay and silt sediments, occasionally interrupted by the sand-dominated layers. 210Pb dating method is applied and indicates that the upper 24 cm sediment spans the sedimentation history of the last 87 years. Along-core variations in sediment characteristics such as organic matter, carbonate, and amorphous silica abundance are indicative of the drought -inducing period based on the significant correlations between sediment characteristics and Self-calibrated Palmer Drought Severity Index. Moreover, the enrichment of carbonates is a great indicator of shallow lake conditions prior to the lake disappearance during the dry period. The chemical composition of sand-dominated units in the sediment core well agrees with that of sand sheets and sand dunes in the catchment. Modern expansion and migration of sand sheets are identified by aerial photo imagery. The insufficient sediment chronology is limiting our interpretation, though; the comparison with the other paleoclimate records helps the establishment of environmental changes in the last millennium. [ABSTRACT FROM AUTHOR]

Inner Mongolia, located in northern China and bordered by Mongolia and Russia, has numerous lakes. Constrained by water scarcity, precious lakes play key roles in degraded grassland ecosystems and the social and economic development of Inner Mongolia. This study combines 1815 Landsat image interpretations and ground-based surveys to track the area changes in 573 lakes in Inner Mongolia during the period 1987–2019. Our results demonstrate that the number of dried-up lakes increased by 0.87 per year, the number of lakes with water areas below 0.1 km2 increased by 1.02 per year, and the number of lakes with water areas between 0.1 and 1 km2 increased by 0.39 per year. The number of lakes with areas larger than 1 km2 shows a decreased or fluctuating trend. The lake area in Inner Mongolia increased at a rate of 7.04 km2/year from 1987 to 1998 but then shows an overall decreasing trend at a rate of 0.71 km2/year over the next 20 years. The period from 1999 to 2010 was the most serious period of lake shrinkage in Inner Mongolia in the past 30 years, with a shrinkage rate of 33.99 km2/year. The climate changes from wet to dry and from dry to wet are the main reasons for the breakpoint occurrence of the lake area time series in the 2000s and 2010s, respectively. The response of lake area changes to climate-related factors has significant regional differences. In addition, intensification of human activities, such as the rapid development of livestock and coal mining, is also the main driver of lake change. The multiple regression model shows that the contribution of climate-related variables and human activity–related variables to the change in lake area over the 1987–2019 time period was about 40% and 60%, respectively. [ABSTRACT FROM AUTHOR]

Lakes are important water resources in Inner Mongolia and play essential roles in flood storage, water source maintenance, aquaculture, water volume regulation, and the regional ecological balance. However, most lakes in Inner Mongolia have undergone significant shrinkage over the past few decades. In order to quantify the lake changes in Inner Mongolia and analyze the factors associated with these changes, information about 546 lakes in seven years (1990, 1995, 2000, 2005, 2010, 2015, and 2018) was retrieved using 30 m resolution Landsat images taken of the entire region over 29 years (1989–2018). In addition, water census data from 2010 and 1:250,000 geological maps were used as references. The analysis revealed that the lakes in Inner Mongolia exhibited rapidly decreasing trends during the past three decades, with both the area and the number of lakes decreasing to a minimum by 2010. The number of lakes with areas of >1 km2 decreased from 384 in 1990 to 301 in 2018; the total area of lakes with individual areas of >1 km2 decreased from 4905.74 km2 in 1990 to 4187.45 km2 in 2018. With respect to the lake distribution among different geomorphological units, the analysis revealed that the lake shrinkage was most pronounced on the West Liaohe Plain, followed by the northern Inner Mongolian Plateau. Furthermore, in relation to different climatic zones, lake shrinkage primarily occurred in the mid-temperate semi-arid zone, wherein the lake area decreased by 776.6 km2. We hypothesize that the changes in the lake number and area in Inner Mongolia resulted from the combined effects of natural conditions and anthropogenic disturbances; possibly, lake shrinkage was mainly driven by the rising temperature and decreasing precipitation, along with water regulation projects, agricultural irrigation, mining development, and population growth that also had non-negligible effects on the lakes. [ABSTRACT FROM AUTHOR]

Monitoring activities on the dynamics of water shrinkage at Lake Limboto are essential to the lake's ecosystem's recovery. A remote sensing technology functions to monitor the dynamics of lake inundation area; this allows one to produce a comprehensive set of spatial and temporal data. Such complex satellite dataset demands extra time, greater storage resources, and greater computing capacity. The Google Earth Engine platform emerges as the alternative to tackle such problems. The present study aims to explore the capability of Google Earth Engine in formulating spatial and temporal maps of the inundation area at Lake Limboto. A total of 345 scenes of Landsat image on the study area (available during the period of 1989-2019) were involved in generating a quick inundation area map of the lake. The whole processes (pre-processing, processing, analysing, and evaluating) were automatized by using the Google Earth Engine interface. The evaluation of mapping result accuracy indicated that the average score of F1-score and Intersection over Union (IoU) was at 0.88 and 0.91, respectively. Moreover, the mapping results of the lake's inundation area from 1989 to 2019 showed that the inundation area tended to decrease significantly in size over time. During the period, the lake's area also shrank from 3023.8 ha in 1989 to 1275.0 ha in 2019. All in all, the spatiotemporal information about the changes in lake area may be treated as a reference for decision-making processes of lake management in the future. [ABSTRACT FROM AUTHOR]

In this study, the spatiotemporal variations of drought and salinity were assessed for the Urmia Lake basin, which is a very critical and challenging ecosystem problem. The lowering of water level in the Urmia Lake and the associated risk of becoming a completely saline land has become an important issue in Iran. In the first step of the study, using the ground- and satellite-based datasets, a new multiscale technique based on Empirical Wavelet Transform (EWT) and Differential Symbolic Entropy (DSE) was proposed to monitor the variations of drought in the selected region. In the next step, variations in the water level and salinity of Urmia Lake and its impacts on the environment were investigated using satellite datasets. Results showed that the Southern parts of the basin were more prone to severe droughts, and there was a direct relationship between entropy and drought intensity. Based on the results, it was concluded that climate change had an impact on the shrinkage of the lake; however, these changes were not solely responsible of causing the dramatic water loss of the Lake. Variations of the Salinity Index (SI) showed that saline lands were mostly seen in the Eastern and Southern parts of the lake, causing negative impacts on air quality and agricultural activities in these parts. It was found that the proper management of water resources would play an effective role in the restoration of the lake. [Display omitted] • Applying a new multiscale technique based on the EWT-DSE for drought monitoring. • Investigating the soil salinity variations via remotely sensing-based datasets. • Detecting saline land via the salinity index obtained from the satellite datasets. • Accuracy of the used methodology was proved in drought and soil salinity monitoring. [ABSTRACT FROM AUTHOR]

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Purpose: The shrinkage of vast inland lakes affects microbially mediated soil biogeochemical processes, which are critical for maintaining ecosystem sustainability, such as microbial diversity and a balanced CH4 budget. Here we aimed to elucidate shifts in the bacterial community and methanotrophy during the shrinkage of a saline lake. Materials and methods: Sediments and soils along a gradient transecting a saline lake, saline riparian land, and grassland were collected. The succession of microbial communities was characterized by high-throughput sequencing of the V4-V5 region of 16S rRNA genes coupled to non-metric multidimensional scaling (NMDS), linear discriminant effect size (LEfSe), community assembly, and co-occurrence network analyses. We further incubated these samples under a 10% CH4 (v/v) atmospheric condition to determine the response of methane oxidation potentials and of methanotrophs to lake shrinkage by using pmoA-based qPCR and amplicon sequencing. Results and discussion: LEfSe and NMDS analyses showed significant differences in bacterial communities among 3 stages of lake shrinkage. The microbial taxa with the highest increase were phylogenetically affiliated with unclassified Rhizobiales, Panacagrimonas, and Pseudomonas in saline and grassland soils when compared with sediments. Microbial community assembly was largely determined by deterministic rather than stochastic processes (NTI > 2). The drastic increase of Methylocystis-like (type II) methanotrophs was observed during lake shrinkage, while type I methanotrophs showed a decreasing trend. However, upon consuming high-concentration methane of about 10%, type I methanotrophs dominated methane-oxidizing communities in lake sediment (Methylomonas), riparian saline soil (Methylomicrobium), and grassland soil (Methylobacter). Structural equation model identified soil pH, C/N ratio, and soil texture as key factors affecting methane oxidation rates and the methanotrophic community. Conclusions: Lake shrinkage showed profound impacts on the overall bacterial communities and methane oxidizers. Soil physico-chemical properties likely shaped the bacterial community and phylogenetically distinct methanotrophs during lake shrinkage. [ABSTRACT FROM AUTHOR]

The changes of lakes directly affect the sustainable development of regional ecological environment and social economy. Affected by the environmental changes and human activities, most of the inland lakes globally have suffered from the area shrinkage and wetland degradation. The protection and restoration of lakes have become a hot public issue. In this study, a lake spatial database of Hubei Province (China) is built to analyze the temporal-spatial dynamic change of lakes in Hubei Province from 1974 to 2014, with the analysis models of lake dynamic change rate (LDCR), lake landscape shape index (LLSI), and lake centroid shift rate (LCSR). The results are as follows: (1) Lakes in Hubei Province showed a shrinking and fragmenting trend from 1975 to 2014. The total area of lakes decreased by 23.08%, and the number of lake increased by 68.03%. (2) The value of LLSI firstly increased and then decreased after 1995, meaning that the lake disturbance degree of human activities decreased firstly and then increased. (3) The lake centroids of Hubei Province were in the Jianghan Plain and shifted to the northwest by 33.67 km from 1975 to 2014, due to the lake shrinkage was more serious in the southeastern than in the northwest. The situation of inland lakes’ shrinkage and degeneration is still very severe. The national and local governments should strengthen the lake management and protection, curb the lake shrinkage and degradation, and promote the healthy and sustainable development of lakes. [ABSTRACT FROM AUTHOR]

In order to better understand the effect of the lake shrinkage on the flood process in a large lake,a quantitative analysis of the relationship between the lake shrinkage and the flooding in Dongting Lake was conducted,for which Jingjiang-Dongting Lake hydrodynamic model was applied and different scenarios of water area in the Dongting Lake were assumed. The results show that the water level and peak discharge will increase,and the peak time will occur earlier with the shrinkage of the lake. The water level in the West and South Dongting Lake would increase by around 2.0 m and the water level in the East Dongting Lake would increase by around 0.4 m if the area of Dongting Lake was shrunk from 2 670 km2 to 1 380 km2 when the 1996-type flood occurred in Dongting Lake. Moreover,the arrival time of the peak water level at Chenglingji station would be about 11 hours earlier,and the peak discharge would increase by about 4 300 m3/s. Hence,the flood disaster would be more severe in the Dongting Lake area if the lake continues to shrink from now on. In addition,the water surface slope changes a little in the West and South Dongting Lake. But the water surface slope increases a lot near the Lujiao station due to the water level in the East Dongting Lake is affected by both of the lake shrinkage and the water level in Yangtze River. [ABSTRACT FROM AUTHOR]

Since the late 1990s, lakes in the southern Tibetan Plateau (TP) have shrunk considerably, which contrasts with the rapid expansion of lakes in the interior TP. Although these spatial trends have been well documented, the underlying hydroclimatic mechanisms are not well understood. Since 2013, we have carried out comprehensive water budget observations at Paiku Co, an alpine lake in the central Himalayas. In this study, we investigate water storage and lake level changes on seasonal to decadal time scales based on extensive in-situ measurements and satellite observations. Bathymetric surveys show that Paiku Co has a mean and maximum water depth of 41.1 m and 72.8 m, respectively, and its water storage was estimated to be 109.3 × 10 8 m 3 in June 2016. On seasonal scale between 2013 and 2017, Paiku Co’s lake level decreased slowly between January and May, increased considerably between June and September, and then decreased rapidly between October and January. On decadal time scale, Paiku Co’s lake level decreased by 3.7 ± 0.3 m and water storage reduced by (10.2 ± 0.8) × 10 8 m 3 between 1972 and 2015, accounting for 8.5% of the total water storage in 1972. This change is consistent with a trend towards drier conditions in the Himalaya region during the recent decades. In contrast, glacial lakes within Paiku Co’s basin expanded rapidly, indicating that, unlike Paiku Co, glacial meltwater was sufficient to compensate the effect of the reduced precipitation. [ABSTRACT FROM AUTHOR]

Intensification of anthropogenic activities has resulted in shrinkage of lakes, which are important sources and sinks of the greenhouse gas methane. Given the increasing interest in the potential importance of CH 4 flux, we employed Illumina Miseq pyrosequencing to examine the effect of lake shrinkage (in a lake that had decreased from 3.7 km 2 to 3.0 km 2 in area during the last 20 years) on the community abundance, activity and structure of methane-cycling microorganisms under four types of soils during lake recession: S ediment (the sediment of the lake, at the maximum depth of 6 m), S lope (soil at a lake water depth of 0.6 m), M arsh (the seasonally flooded marsh and wetland formed after recession of the lake) and M eadow (the meadow formed after recession of the lake, about 200 m from the lake). The results showed that lake shrinkage decreased the relative abundance and transcripts of soil methanogens and methanotrophs along the gradient from S ediment to S lope to M arsh . M eadow , having the longest drying time, had both higher soil nutrient concentrations (including dissolved organic carbon, total carbon and total nitrogen), and higher relative abundance of 16S rRNA genes and transcripts of methanogens and methanotrophs. Results of methanogen community structure analysis indicated ‘resistance’ to change under lake shrinkage, with all communities dominated by Methanosaetaceae except the S lope community, which was dominated by Methanoregulaceae, while the dominant methanotroph changed from Methylomicrobium (a Type I methanotroph) (in S ediment , S lope and M arsh ) to Methylocaldum (Type I) and Methylosinus (Type II) (in M eadow ) under lake shrinkage. Taken together, the microbial community data indicate that CH 4 production and consumption potentially recedes under lake shrinkage, whereas the formation of M eadow may increase CH 4 emission and oxidization potential. [ABSTRACT FROM AUTHOR]

The Lake Urmiah has undergone a drastic shrinkage in size over the past few decades. The initial intention of this paper is to present an approach for determining the so called “salient times” during which the trend of the shrinkage process is accelerated or decelerated. To find these salient times, a quasi_continuous curve was optimally fitted to the Topex altimetry data within the period 1998 to 2006. To find the salient points within this period of time, the points of inflections of the fitted curve is computed using a second derivative approach. The water volume was also computed using 16 cloud free Landsat images of the Lake within the periods of 1998 to 2006. In the first stage of the water volume calculation, the pixels of the Lake were segmented using the Automated Water Extraction Index (AWEI) and the shorelines of the Lake were extracted by a boundary detecting operator using the generated binary image of the Lake surface. The water volume fluctuation rate was then computed under the assumption that the two successive Lake surfaces and their corresponding water level differences demonstrate approximately a truncated pyramid. The analysis of the water level fluctuation rates were further extended by a sinusoidal curve fitted to the Topex altimetry data. This curve was intended to model the seasonal fluctuations of the water level. In the final stage of this article, the correlation between the fluctuation rates and the precipitation and temperature variations were also numerically determined. This paper reports in some details the stages mentioned above. [ABSTRACT FROM AUTHOR]

Lakes are widely distributed on the Mongolian Plateau and, as critical water sources, have sustained Mongolian pastures for hundreds of years. However, the plateau has experienced significant lake shrinkage and grassland degradation during the past several decades. To quantify the changes in all of the lakes on the plateau and the associated driving factors, we performed a satellite- based survey using multitemporal Landsat images from the 1970s to 2000s, combined with ground-based censuses. Our results document a rapid loss of lakes on the plateau in the past decades: the number of lakes with a water surface area >1 km2 decreased from 785 in the late 1980s to 577 in 2010, with a greater rate of decrease (34.0%) in Inner Mongolia of China than in Mongolia (17.6%). This decrease has been particularly pronounced since the late 1990s in Inner Mongolia and the number of lakes >10 km2 has declined by 30.0%. The statistical analyses suggested that in Mongolia precipitation was the dominant driver for the lake changes, and in Inner Mongolia coal mining was most important in its grassland area and irrigation was the leading factor in its cultivated area. The deterioration of lakes is expected to continue in the following decades not only because of changing climate but also increasing exploitation of underground mineral and groundwater resources on the plateau. To protect grasslands and the indigenous nomads, effective action is urgently required to save these valuable lakes from further deterioration. [ABSTRACT FROM AUTHOR]

• An isotope mass balance model considering the lake evaporation was established. • 10–20% (average of 15%) of the original lake water in the Middle Holocene remains. • The total groundwater recharge to lakes in the Badain Jaran Desert is 1.63 × 107 m3/yr. • The humidity and atmospheric vapor δ a 18O dominate the desert lakes δ18O evolution. The evolutionary stages of the different lakes in the Badain Jaran Desert (BJD) are unknown, and there is a need to elucidate the hydrological implications of the hydrodynamic environmental differences among these lakes. In this study, a stable isotope mass balance model incorporating the effect of evaporation from the lake basins was developed, and the model was used to calculate the remaining water fraction f of 94 lakes relative to the high lake levels in the Middle Holocene, as well as the groundwater recharge rate χ G to the lakes. The results show that only 10–20 % (average of 15 %) of the original lake water remains. One-third of the lakes have become terminal lakes, and half are still gradually drying. If the climatic conditions remain unchanged, the water levels of these lakes will drop by an average of 11 mm per year. χ G has a certain degree of correlation with elevation, suggesting the likely presence of more water recharge sources for the north lakes, which may include the Beida Mountains and the Zongnai Mountains. The total annual groundwater recharge to all of the lakes in the BJD is 1.63 × 107 m3/yr. The δ18O evolution model of a typical lake (Cherigele Lake) reveals that humidity h and atmospheric vapor δ a 18O play the leading role in the evolution of the lake δ18O, suggesting that this model may serve as a tool for estimating lake evaporation and for reconstructing the paleoclimate. The findings of this study provide support for analyzing the evolution and future trends of lakes in arid desert areas, as well as deeper insights into the water cycle in the BJD. [ABSTRACT FROM AUTHOR]

It has been shown that the disappearance of lakes is understood as a decrease in water resources and not only as the shrinkage of their area. It is mainly a result of the process of infill of lake basins. The conclusion is based on observational data collected for 25 lakes. In a period of over 50 years the area of lakes has decreased by 5.6% (compared to IIF data), while volume has decreased by 9.9%. [ABSTRACT FROM AUTHOR]

This study explores the mechanisms behind the rapid shrinkage of Limboto Lake, Gorontalo, Indonesia, using remotely sensed imagery and river outcrop investigation data. The results show that more than 70% of the sedimentation resulting in shrinkage is contributed by riverbank erosion causing rivers to drain into the lake during the period 2003–2017. From geological investigation, it is found that the lowland area to the west of Limboto Lake comprises 1 m of flood sediments, followed by at least 5 m of fine-grained inner bay sediments. Severe riverbank erosion is also observed at many points. Hence, it is concluded that the shrinkage of Limboto Lake resulted from rapid-induced rapid erosion of inner bay sediments formed during plate collision which readily flowed into and were deposited in Limboto Lake; this created a delta, especially on the west side of the lake. Accelerated sedimentation caused by river erosion has led to rapid lake shrinkage. This phenomenon could be typical of the transformation of enclosed seas into lakes by the rapid uplifting movement of land in collision zones. [ABSTRACT FROM AUTHOR]

Lake Urmia has experienced severe environmental degradation, mainly characterized by the enormous reduction of its surface area and water level. This issue has been mainly attributed to land-use and land-cover changes, in particular related to agricultural expansion and intensification. In this study, we used the DPSIR framework (D: driving forces, P: pressures, S: states, I: impacts, and R: responses) to systematically describe the ecosystem service dynamics related to anthropogenic activities and climatic parameters in the region. We reviewed the literature and used remote sensing, agricultural, climatic and hydrological data together with expert knowledge to assess the main driving forces and pressures, resulting land-use transitions and their spatiotemporal impacts on ecosystem services and biodiversity using a matrix-based assessment approach. We identified population growth, economic incentives and climate change as the most important driving forces, leading to altered agricultural activities, numerous dam constructions and droughts. Since 1987 cropland areas doubled at the expense of bare soils and natural vegetation, the lake hast lost more than half of its surface area, urban and freshwater areas increased threefold and by 50%, respectively. This favored crop and freshwater provision, while all other ecosystem services remained nearly constant or decreased, though spatial patterns were heterogeneous. For example, regulating and cultural services, and biodiversity mainly decreased at the shorelines of the lake, while provisioning services increased along the major rivers and close to cities. To address the land-use transitions with the most profound impact on ecosystem service provision, we recommend the following measures: increase the water supply to the lake, reduce cropland expansion, manage existing croplands more sustainably and protect natural vegetation. Our study provides a comprehensive overview of the regional ecosystem service dynamics and a valuable baseline for future research and environmental management in the basin. Unlabelled Image • The Lake Urmia basin has experienced substantial land use and land cover change (LULC). • We identified driving forces and pressures of LULC and their impacts on ecosystem services (ES). • Lake shrinkage has negative implications for most ES and biodiversity. • Environmental and socioeconomic dynamics of the basin are driven by agriculture. [ABSTRACT FROM AUTHOR]