Assessment of rehabilitation strategies for lakes affected by anthropogenic and climatic changes: A case study of the Urmia Lake, Iran

Over the last three decades,more than half of the world's large lakes and wetlands have experienced significant shrinkage,primarily due to climate change and extensive water consumption for agriculture and other human needs.The desiccation of lakes leads to severe environmental,economic,and social repercussions.Urmia Lake,located in northwestern Iran and representing a vital natural ecosystem,has experienced a volume reduction of over 90.0%.Our research evaluated diverse water management strategies within the Urmia Lake basin and prospects of inter-basin water transfers.This study focused on strategies to safeguard the environmental water rights of the Urmia Lake by utilizing the modeling and simulating(MODSIM)model.The model simulated changes in the lake's water volume under various scenarios.These included diverting water from incoming rivers,cutting agricultural water use by 40.0%,releasing dam water in non-agricultural seasons,treated wastewater utilization,and inter-basin transfers.Analytical hierarchy process(AHP)was utilized to analyze the simulation results.Expert opinions with AHP analysis,acted as a multi-criteria decision-making tool to evaluate the simulation and determine the optimal water supply source priority for the Urmia Lake.Our findings underscore the critical importance of reducing agricultural water consumption as the foremost step in preserving the lake.Following this,inter-basin water transfers are suggested,with a detailed consideration of the inherent challenges and limitations faced by the source watersheds.It is imperative to conduct assessments on the impacts of these transfers on the downstream users and the potential environmental risks,advocating for a diplomatic and cooperative approach with adjacent country.This study also aims to forecast the volumes of water that can be transferred under different climatic conditions—drought,normal,and wet years—to inform strategic water management planning for the Urmia Lake.According to our projection,implementing the strategic scenarios outlined could significantly augment the lake's level and volume,potentially by 3.57×109–9.38×109 m3 over the coming 10 a and 3.57×109–10.70×109 m3 in the subsequent 15 a.

Impact assessment of climate change and human activities on annual highest water level of Taihu Lake

The annual highest water level of Taihu Lake （Zm） is very significant for flood management in the Taihu Basin. This paper first describes the inter-annual and intra-annual traits of Zm from 1956 to 2000. Then, using the Mann-Kenall （MK） and Spearman （SP） nonparametric tests, the long-term change trends of area precipitation and pan evaporation in the Taihu Basin are determined. Meanwhile, using the Morlet wavelet transformation, the fluctuation patterns and change points of precipitation and pan evaporation are analyzed. Also, human activities in the Taihu Basin are described, including land use change and hydraulic project construction. Finally, the relationship between Zm, the water level of Taihu Lake 30 days prior to the day of Zm （Z0）, and the 30-day total precipitation and pan evaporation prior to the day of Zm （P and E0, respectively） is described based on multi-linear regression equations. The relative influence of climate change and human activities on the change of Zm is quantitatively ascertained. The results demonstrate that： （1） Zm was distinctly higher during the 1980-2000 period than during the 1956-1979 period, and the 30 days prior to the day of Zm are the key phase influencing Zm every year; （2） P increased significantly at a confidence level of 95% during the 1956-2000 period, while the reverse was true for E0; （3） The relationship between Zm, P and E0 distinctly changed after 1980; （4） Climate change and human activities together caused frequent occurrences of high Zm after 1980; （5） Climate change caused a substantially greater Zm difference between the 1956-1979 and 1980-2000 periods than human activities. Climate change, as represented by P and E0, was the dominant factor raising Zm, with a relative influence ratio of 83.6%, while human activities had a smaller influence ratio of 16.4%.

Relationship Between Changes of River-lake Networks and Water Levels in Typical Regions of Taihu Lake Basin,China

The typical regions of the Taihu Lake Basin,China,were selected to analyze the variation characteristics of river-lake networks under intensive human activities.The characteristics of the fractal dimension of river networks and lakes for different periods were investigated and the influences of river system evolution on water level changes were further explored through the comparison of their fractal characters.The results are as follows:1) River network development of the study area is becoming more monotonous and more simple;the number of lakes is reducing significantly,and the water surface ratio has dropped significantly since the 1980s.2) The box dimension of the river networks in all the cities of the study area decreased slowly from the 1960s to the 1980s,while the decrease was significant from the 1980s to the 2000s.The variations of lake correlation dimension are similar to those of the river network box dimensions.This is unfavorable for the storage capacity of the river networks and lakes.3) The Hurst exponents of water levels were all between 0.5 and 1.0 from the 1960s to the 1980s,while decreased in the 2000s,indicating the decline in persistence and increase in the complexity of water level series.The paper draws a conclusion that the relationship between the fractal dimension of river-lake networks and the Hurst exponents of the water level series can reveal the impacts of river system changes on flood disasters to some extent:the disappearance of river networks and lakes will increase the possibility of flood occurrence.

WATER BALANCE AND WATER LEVEL CHANGE IN QINGHAI LAKE

The Qinghai Lake, the largest closed interior saline lake in China with the area of296611 km^2 and the altitude of 3000m, is located in the northeast of Tibet Plateau. It is sofar from industrial area that it is in the natural to semi-naturnal state. This means it isweakly influenced by human activities. So, the lake is a good place to investigateenvironmental and climatic changes. In fact, during last hundreds of years the water

The World’s Largest Lakes Water Level Changes in the Context of Global Warming

The article is focused on the assessment of changes in the average annual water levels of large lakes of the planet in the changing climate conditions characteristic of the recent decades. Eight large lakes, i.e.Baikal, Balkhash, Superior, Issyk-Kul, Ladoga, Onega, Ontario, and Erie, located on the territory of Eurasia and North America, were chosen as the research objects. They were selected because of the availability of a long-term observations series of the water level. As is known, long-term changes in the lakes water level result from variation in the water volume. The latter depends on the?ratios between the water balance components of the lake that have developed during a given year, which, in turn, reflect the climatic conditions of the respective years. The features of the water balance structure of the above-mentioned?lakes and the intra-annual course of the water level are considered. The available long-term records of observational data on all selected lakes and their stations were divided into two periods: from 1960 to 1979 (the period of stationary climatic situation) and from 1980 to 2008 (the period of non-stationary climatic situation). The homogeneity and significance of trends in the long-term water level series of records have been estimated. It has been established that over the second period the nature and magnitude of the lakes water levels variations differ significantly. For lakes Balkhash, Issyk-Kul, Ladoga, Superior, and Erie, there is a general tendency for a decrease in water levels. For the remaining three lakes (Baikal, Onega, and Ontario), the opposite tendency has been noted: the levels of these lakes increased. Quantitatively, the range of changes in water levels on the lakes in question over the period of 1980-2008 ranged from -4 cm to +26 cm.

Evaluation of spatial-temporal dynamics in surface water temperature of Qinghai Lake from 2001 to 2010 by using MODIS data

Lake surface water temperature （SWT） is an important indicator of lake state relative to its water chemistry and aquatic ecosystem,in addition to being an important regional climate indicator.However,few literatures involving spatial-temporal changes of lake SWT in the Qinghai-Tibet Plateau,including Qinghai Lake,are available.Our objective is to study the spatial-temporal changes in SWT of Qinghai Lake from 2001 to 2010,using Moderate-resolution Imaging Spectroradiometer （MODIS） data.Based on each pixel,we calculated the temporal SWT variations and long-term trends,compared the spatial patterns of annual average SWT in different years,and mapped and analyzed the seasonal cycles of the spatial patterns of SWT.The results revealed that the differences between the average daily SWT and air temperature during the temperature decreasing phase were relatively larger than those during the temperature increasing phase.The increasing rate of the annual average SWT during the study period was about 0.01℃/a,followed by an increasing rate of about 0.05℃/a in annual average air temperature.The annual average SWT from 2001 to 2010 showed similar spatial patterns,while the SWT spatial changes from January to December demonstrated an interesting seasonal reversion pattern.The high-temperature area transformed stepwise from the south to the north regions and then back to the south region from January to December,whereas the low-temperature area demonstrated a reversed annual cyclical trace.The spatial-temporal patterns of SWTs were shaped by the topography of the lake basin and the distribution of drainages.

The response of lake change to climate fluctuation in north Qinghai-Tibet Plateau in last 30 years

According to the analysis of the climate materials including the topographic map in 1975, the TM and CBERS satellite remote sensing materials from the 1980s to 2005 as well as the air temperature, precipitation, evaporation rate, maximum depth of snow and the biggest depth of frozen soil in the past 45 years, the water level area of four lakes at the southeast of Nagqu, Tibet including Barn Co, Pung Co, Dung Co and Nuripung Co show a distinct trend of expansion in the past 30 years. In 2005, the water level area of the above four lakes increased by 48.2 km^2, 38.2 km^2, 19.8 km^2 and 26.0 km^2 respectively compared to 1975, with the respective increase rate of 25.6%, 28.2%, 16.2% and 37.6%. That is closely related to the warming and humidified climate change in the recent years such as rise of the air temperature increase of the precipitation, decrease of the evaporation rate and permafrost degradation.

Effects of climate change and land use/cover change on the volume of the Qinghai Lake in China

Qinghai Lake is the largest saline lake in China.The change in the lake volume is an indicator of the variation in water resources and their response to climate change on the Qinghai-Tibetan Plateau(QTP)in China.The present study quantitatively evaluated the effects of climate change and land use/cover change(LUCC)on the lake volume of the Qinghai Lake in China from 1958 to 2018,which is crucial for water resources management in the Qinghai Lake Basin.To explore the effects of climate change and LUCC on the Qinghai Lake volume,we analyzed the lake level observation data and multi-period land use/land cover(LULC)data by using an improved lake volume estimation method and Integrated Valuation of Ecosystem Services and Trade-offs(InVEST)model.Our results showed that the lake level decreased at the rate of 0.08 m/a from 1958 to 2004 and increased at the rate of 0.16 m/a from 2004 to 2018.The lake volume decreased by 105.40×10^(8) m^(3) from 1958 to 2004,with the rate of 2.24×10^(8) m^(3)/a,whereas it increased by 74.02×10^(8) m^(3) from 2004 to 2018,with the rate of 4.66×10^(8) m^(3)/a.Further,the climate of the Qinghai Lake Basin changed from warm-dry to warm-humid.From 1958 to 2018,the increase in precipitation and the decrease in evaporation controlled the change of the lake volume,which were the main climatic factors affecting the lake volume change.From 1977 to 2018,the measured water yield showed an"increase-decrease-increase"fluctuation in the Qinghai Lake Basin.The effects of climate change and LUCC on the measured water yield were obviously different.From 1977 to 2018,the contribution rate of LUCC was -0.76% and that of climate change was 100.76%;the corresponding rates were 8.57% and 91.43% from 1977 to 2004,respectively,and -4.25% and 104.25% from 2004 to 2018,respectively.Quantitative analysis of the effects and contribution rates of climate change and LUCC on the Qinghai Lake volume revealed the scientific significance of climate change and LUCC,as well as their individual and combined effects in the Qinghai Lake Basin and on the QTP.This study can contribute to the water resources management and regional sustainable development of the Qinghai Lake Basin.

Impacts of climate change and human activities on water resources in the Ebinur Lake Basin, Northwest China

Changing climatic conditions and extensive human activities have influenced the global water cycle.In recent years,significant changes in climate and land use have degraded the watershed ecosystem of the Ebinur Lake Basin in Xinjiang,Northwest China.In this paper,variations of runoff,temperature,precipitation,reference evapotranspiration,lake area,socio-economic water usage,groundwater level and water quality in the Ebinur Lake Basin from 1961 to 2015 were systematically analyzed by the Mann-Kendall test methods(M-K)mutation test,the cumulative levelling method,the climate-sensitive method and land-use change index.In addition,we evaluated the effects of human activities on land use change and water quality.The results reveal that there was a significant increase in temperature and precipitation from 1961 to 2015,despite a decrease in reference evapotranspiration.The Wenquan station was not significantly affected by human activities as it is situated at a higher altitude.Runoff at this station increased significantly with climate warming.In contrast,runoff at the Jinghe station was severely affected by numerous human activities.Runoff decreased without obvious fluctuations.The contributions of climate change to runoff variation at the Jinghe and Wenquan stations were 46.87%and 58.94%,respectively;and the contributions of human activities were 53.13%and 41.06%,respectively.Land-use patterns in the basin have changed significantly between 1990 and 2015:urban and rural constructed lands,saline-alkali land,bare land,cultivated land,and forest land have expanded,while areas under grassland,lake,ice/snow and river/channel have declined.Human activities have dramatically intensified land degradation and desertification.From 1961 to 2015,both the inflow into the Ebinur Lake and the area of the lake have declined year by year;groundwater levels have dropped significantly,and the water quality has deteriorated during the study period.In the oasis irrigation area below the runoff pass,human activities mainly influenced the utilization mode and quantity of water resources.Changes in the hydrology and quantity of water resources were driven primarily by the continuous expansion of cultivated land and oasis,as well as the growth of population and the construction of hydraulic engineering projects.After 2015,the effects of some ecological protection projects were observed.However,there was no obvious sign of ecological improvement in the basin,and some environmental problems continue to persist.On this basis,this study recommends that the expansion of oasis should be limited according to the carrying capacity of the local water bodies.Moreover,in order to ensure the ecological security of the basin,it is necessary to determine the optimal oasis area for sustainable development and improve the efficiency of water resources exploitation and utilization.

THE STUDY ON CLIMATIC CHANGES AND LAKE LEVEL FLUCTUATIONS OF OINGHAIB LAKE IN HOLOCENE

According to loess and palaeosol climatic record, field observation, analysis data and 14C dating, we discuss the climatic changes and the water level fluctuations of Qinghai Lake. It is pointed out that there were four relatively warm and moist stages in Qinghai Lake basin during the Holocene. They formed in the periods from 10,300 yr.B.P. to 8,500 yr.B.P., 7,000 yr.B.P. to 3,500 yr.B.P., 2,800 yr.B.P. to 2,000 yr.B.P. and from 1,300 yr.B.P. up to now. The climate in the Holocene optimum period, from 7,000 yr.B.P. to 3,500 yr.B.P., was much warmer and moister than that today. Polypodium plant grew luxuriantly around Qinghai Lake. The annual temperature was 2.5℃ higher than that today, but there was no forest at Qinghai Lake shore. It is found that there was a good relationship between precipitation and water level fluctuation. In warm and moist period water level was high and in the cold and dry period it was low in the Holocene. There were four high water level periods for Qinghai Lake in the

THE HYDROLOGICAL CHARACTERISTICS AND WATER BUDGET OF QINGHAI LAKE DRAINAGE BASIN

The rapid shrinkage of the surface area reflects the long-term deficit water budget of Qinghai Lake. Study of the yearly hydrology and meteorology in the lake catchment basin and the hydrologic factors as well as water budget led to the conclusion that evaporation exceeding the water input resulted in the drop of lake level, thai the obvious decrease of runoff to the lake and precipitation on the catchment accelerated the falling of lake level before 1987. and that increase of about 6.7% in rainfall on the whole basin will balance the lake’s water budget.

RELATIONSHIP BETWEEN QINGHAI LAKE LEVEL DESCENDING AND ARTIFICIAL WATER－CONSUMPTION

Qinghai Lake is the largest inland lake in China. It is a closed-drainage saline lake located at 3194m above sea level in the northeastern Qinghai-Xizang (Tibet) Plateau. Qinghai Lake region, about 36°15' -38°20' N and 97°50, - 101°20' E,is a closed basin

Growth of the Sayram Lake and retreat of its water-supplying glaciers in the Tianshan Mountains from 1972 to 2011

Inland lakes and alpine glaciers are important constituents of water resources in arid and semiarid regions. Understanding their variations is critical for both an accurate evaluation of the dynamic changes of water resources and the retrieval of climatic information. On the basis of earlier researches, this study investigated the growth of the Sayram Lake and the retreat of its water-supplying glaciers in the Tianshan Mountains using long-term sequenced remote sensing images. Our results show that over the past 40 years, the surface area and the water level of the lake has increased by 12.0±0.3 km2 and 2.8 m, respectively, and the area of its water-supplying glaciers has decreased continuously since the early 1970s with a total reduction of about–2.13±0.03 km2. Our study has indicative significance to the research of regional climate change.

Groundwater contributions in water-salt balances of the lakes in the Badain Jaran Desert,China

Groundwater-fed lakes are essential for the ecology in arid and semiarid regions.As a typical arid region,the Badain Jaran Desert （BJD） is famous in the world for the presence of a large number of groundwater-fed saline lakes among the mega dunes.Based on the up to date geological surveys and observations,this study analyzed the groundwater contributions in water-salt balances of the lakes in the desert.We found different types of springs,including the sublacustrine springs that indicate an upward flow of groundwater under the lakebed.A simplified water balance model was developed to analyze the seasonal variations of water level in the Sumu Barun Jaran Lake,which revealed an approximately steady groundwater discharge in the lake and explained why the amplitude of seasonal changes in lake level is less than 0.5 m.In addition,a salt balance model was developed to evaluate the salt accumulations in the groundwater-fed lakes.The relative salt accumulation time is 800–7,000 years in typical saline lakes,which were estimated from the concentration of Cl-,indicating a long history evolution for the lakes in the BJD.Further researches are recommended to provide comprehensive investigations on the interactions between the lakes and groundwater in the BJD.

Hydro-Chemical Processes in Lake Qinghai throughout Climate Warming: In Situ Investigations of the Largest Lake in China

In the wake of climate warming, the water level of Lake Qinghai has been continuously and rapidly declining during the past decades, causing the regional government and citizens to worry about its future as a water resource. To understand the lake evolution process, the hydro-chemical characteristics of Lake Qinghai were investigated in August of 2008. The results show that Na+ and Cl- are the dominant cations and anions in the lake water, respectively, and hydrochemistry type is Cl-- Na+ with an obvious characteristic of a saline lake. The Gibbs plot illuminates that evaporation/crystallization is responsible for the chemical composition of the lake water. The variation in hydro-chemical regime might be attributed to the reduced lake levels between 1960s and 2000s. The lake level significantly correlated with the precipitation and evaporation in the Lake Qinghai catchment. In addition, changes of the lake level in the future are simulated according to climate warming scenarios from the IPCC report. The simulated results suggest that the lake level could rise again in the following decades due to the increased precipitation under the climate warming conditions, which is already a trend in the lake level observation data.

近60年洞庭湖水位演变态势研究

辨析洞庭湖历史水位演变态势对保护湖泊生态系统健康运转以及确保长江中下游防洪安全和水资源利用均至关重要。为了定量评估洞庭湖近60年来水位变化特征、程度及规律,基于洞庭湖鹿角、杨柳潭和南咀水文站19612020年逐日水位监测数据,应用Mann-Kendall检验法、小波分析法、累积距平法、滑动t检验法等方法对洞庭湖水位变化趋势性、周期性、突变性进行分析,进而采用IHA-RVA法综合评价洞庭湖突变年前后各站点水位改变度和整体水位改变度。研究结果表明:(1)19612020年,鹿角站和杨柳潭站年均水位呈上升趋势,南咀站年均水位呈下降趋势;3个站点水位周期性变化较为明显,呈现4~5个时间尺度的周期变化规律,第一主周期为55~56年;鹿角站水位突变年份为1979、2003年,杨柳潭站水位突变年份为1978、2003年,南咀站水位突变年份为2003年,综合确定2003年为3个站点突变年份。(2)通过分析突变前后3个站点的水位、时间、频率、延时和改变率5组32个水位指标改变度,发现杨柳潭站水位改变度大于鹿角站和南咀站,鹿角、杨柳潭、南咀站的整体水位改变度分别为43%、48%、42%,均属于中度改变。该研究可为进一步解析洞庭湖水文情势演变规律以及为长江中下游通江湖泊水资源合理利用和水生态环境保护提供参考依据和数据支撑。

越冬期水位变化下菜子湖水鸟取食集团结构及多样性分析

2018—2023年越冬期,对菜子湖的水鸟资源进行调查,共记录到水鸟7目12科59种,其中,国家一级保护动物5种,国家二级保护动物9种。对水鸟取食集团群落结构进行分析,结果表明,不同取食集团水鸟群落多样性指数存在显著差异,不同类型多样性指数变化幅度是Shannon-Wiener多样性指数>Margalef丰富度指数>Simpson优势度指数>Pielou均匀度指数。不同取食集团水鸟的数量对水位变化响应存在一定差异,其中,食鱼组、食草组、食底栖动物组的数量与水位之间存在显著负相关关系,水位变化对水域、草本沼泽、泥滩等3种生境的面积具有显著影响。未来应从水位优化调控入手,维持越冬期水鸟丰富食物资源,对提高菜子湖水鸟群落多样性具有重要意义。

湖泊与河流水文连通量化计算模型及其应用

湖泊与河流水文连通的量化是指导河湖保护与治理的关键之一,也是当前河湖生态复苏研究的热点问题。本文提出了一种湖泊与河流水文连通的量化计算模型,仅需少量实测或水动力模拟数据进行校验,即可量化计算单一或多个连通水道的河湖水文连通度。水位变化率与水位是决定水文连通的主控因子,水体交换强度与水位变化率呈线性正相关,且其增长速率与水位呈正相关。提出的水体交换流量计算方法可估算湖泊与长江水体交换流量。同等水位及水位变化率条件下,湖泊向长江输出水流的效率大于长江向湖泊灌入水流的效率。水文连通度峰值一般出现在整体上升或下降区间内的变异点,通过改变水位抬升或下降过程,可有效提升水文连通度均值及峰值,指导面向湖泊水生态环境改善的生态调度等。

1985—2021年青藏高原典型湖泊水文特征及关键影响因素

[目的]青藏高原的湖泊是气候变化的重要指示器,其扩张或缩减亦对青藏高原自然环境产生重要影响。[方法]选取位于青藏高原不同气候子区的3个典型湖泊(青海湖、羊卓雍错、乌兰乌拉湖),采用遥感监测手段,研究3个典型湖泊1985—2021年水文特征的时空变化规律,揭示关键气候因子的作用,并进一步探讨冰川和冻土对典型湖泊的影响。[结果]研究期间,青海湖的面积和水位呈显著上升趋势,面积增长238.68 km^(2),水位增长1.32 m,空间上则向东西方向扩张;羊卓雍错湖泊面积呈先波动上升后减少趋势,面积和水位分别减少16.31 km^(2)和3.25 m,在空间上整体由四周向中心的萎缩态势;乌兰乌拉湖面积和水位呈显著上升趋势,分别增长125.57 km^(2)和8.12 m,扩张区域主要集中在南部。[结论]在暖湿化环境下,降水增多和冰川冻土加速融化导致的湖泊扩张是青藏高原最为突出的环境变化特征,其中,降水量变化是影响青海湖和羊湖面积变化的关键因素,且面积变化和降水量具有滞后性;而乌兰乌拉湖水位上升的主要原因是气温升高引起冻土的季节融化。探索青藏高原湖泊面积的变化,对深入研究全球气候变化及地表水资源评估具有重要指导意义。

青海湖水位演变及其影响因子分析

青海湖不仅是我国最大的湖泊,也是国家生态安全战略格局的重要组成部分。在全球变暖的背景下,青海湖水位急剧变化,其对周边的交通设施、居民安全和畜牧业发展等影响较大,因此需要对气候变化下的青海湖水位演变特征及其水量平衡进行研究。本文基于布哈河口水文站、下社水文站的水文数据,刚察气象站、CMFD气象数据以及水量平衡方程,首先分析了青海湖1956-2020年的年际水位演变特征和年内水位变化特征,以及水量平衡分量——入湖径流(R_(s))、湖面降水(P)和湖面蒸发(E)对水位变化的影响;其次揭示了相同月份计算的水位值变化与R_(s)、P和E的变化是同步的;最后进一步通过岭回归方法定量计算了R_(s)、P和E对基于12月份计算的青海湖水位变化的贡献率。研究结果表明:青海湖年均水位在1956-2004年以0.8 m·(10a)^(-1)的速率下降,其中在1979-2004年间下降的主要原因是E大于(P+R_(s));2004-2020年以1.9 m·(10a)^(-1)的速率上升,其中在2004-2018年间上升的主要原因是P和R_(s)的增加;青海湖水位有明显的年内变化,5月水位开始上涨,9月达到最高,其与R_(s)、P和E的月变化一致;当年的P、R_(s)、E变化对9-12月相同月份年均水位变化的影响大于去年,当年的P、R_(s)、E对12月年均水位变化的贡献率分别为10%、70%和20%。