Impact of climate change and human activities on the spatiotemporal dynamics of surface water area in Gansu Province, China

Understanding the dynamics of surface water area and their drivers is crucial for human survival and ecosystem stability in inland arid and semi-arid areas.This study took Gansu Province,China,a typical area with complex terrain and variable climate,as the research subject.Based on Google Earth Engine,we used Landsat data and the Open-surface Water Detection Method with Enhanced Impurity Control method to monitor the spatiotemporal dynamics of surface water area in Gansu Province from 1985 to 2022,and quantitatively analyzed the main causes of regional differences in surface water area.The findings revealed that surface water area in Gansu Province expanded by 406.88 km2 from 1985 to 2022.Seasonal surface water area exhibited significant fluctuations,while permanent surface water area showed a steady increase.Notably,terrestrial water storage exhibited a trend of first decreasing and then increasing,correlated with the dynamics of surface water area.Climate change and human activities jointly affected surface hydrological processes,with the impact of climate change being slightly higher than that of human activities.Spatially,climate change affected the'source'of surface water to a greater extent,while human activities tended to affect the'destination'of surface water.Challenges of surface water resources faced by inland arid and semi-arid areas like Gansu Province are multifaceted.Therefore,we summarized the surface hydrology patterns typical in inland arid and semi-arid areas and tailored surface water'supply-demand'balance strategies.The study not only sheds light on the dynamics of surface water area in Gansu Province,but also offers valuable insights for ecological protection and surface water resource management in inland arid and semi-arid areas facing water scarcity.

Seasonal constraint of dynamic water temperature on riverine dissolved inorganic nitrogen transport in land surface modeling

水体温度变化对河流可溶性无机氮(DIN)输送有着强烈控制作用.然而,在全球尺度上河流DIN输送量对水温度变化的响应尚不清楚.因此,本文基于陆面过程模式,耦合河流水温估算和DIN传输方案,设定有,无动态水温情景,对比研究陆面模拟中水温变化对河流DIN通量变化的影响.结果表明:在考虑水温动态变化后,在30°N和30°S之间, DIN通量年振幅减小5%–25%.在中国东部地区,水温动态变化使河流DIN通量在夏季减少1%–3%,在冬季增加1%–5%,对DIN通量具有明显的季节性约束作用,表明动态水温的表达在河流DIN输送模拟中的重要性.

Impact of climate change on the surface water of Kaidu River Basin

To reveal the changing trend and annual distribution of the surface water hydrology and the local climate in the Bayanbuluk alpine-cold wetlands in the past 50 years, we used temperature, precipitation, different rank precipitation days, evaporation, water vapor pressure, relative humidity, dust storm days and snow depth to analyze their temporal variations. We conclude that there were no distinct changes in annual mean temperature, and no obvious changes in the maximum or minimum temperatures. Precipitation in warm season was the main water source in the wetlands of the study area and accounted for 92.0% of the annual total. Precipitation dropped to the lowest in the mid-1980s in the past 50 years and then increased gradually. The runoff of the Kaidu River has increased since 1987 which has a good linear response to the annual precipitation and mean temperature in Bayanbuluk alpine-cold wetland. Climate change also affected ecosystems in this area due to its direct relations to the surface water environment.

Temporal-spatial Change of Cr Content in Bottom Waters

Based on the investigation data of Jiaozhou Bay waters in 1981,current situation and horizontal distribution of Cr content in bottom waters of Jiaozhou Bay mouth were studied. Results showed that in bottom waters of Jiaozhou Bay center,Cr content changed from 0. 50 to3. 78 μg/L in April. In August,Cr content changed from 0. 14 to 1. 42 μg/L in bottom waters of Jiaozhou Bay mouth. It showed that Cr content corresponded with national class-one seawater quality standard(50. 00 μg/L) at different times and spaces,and Cr content was far less than5. 00 μg/L. Therefore,under the effect of vertical water body,water quality was clean in bottom waters of Jiaozhou Bay,which was not polluted by Cr. In bottom waters of Jiaozhou Bay center in April and bottom waters of Jiaozhou Bay mouth in August,Cr transported by the river came to the bottom layer from surface layer by passing through water body in temporal-spatial change process. Under the effects of gravity and water flow,Cr continuously and quickly sank to the sea bottom. It verified the sedimentation process of Cr content.

The Impacts of Climate Change on the Availability of Surface Water Resources in Jordan

Climate change in the Middle East area including Jordan has started to be reflected in decreasing precipitation and increasing temperatures with their impacts on the availability of surface and groundwater. This article aims to evaluate the impacts of decreasing or increasing precipitation by 10% and 20% on the quantities of flood runoff based on recorded precipitation and runoffs of catchments during the past 60 to 70 years of observation, during which the precipitation in individual or a few years increased or decreased by tens of percentages relative to the long-term average precipitation. The results of quantification show that in Jordan as a whole, decreasing precipitation by 10% and 20% has historically (during the recording period) resulted in reductions in flood flows by 26.2% and 52.8% and that increasing precipitation by 10% and 20% has resulted in increases in flood flows by 26.4% and 56.5% respectively. These results look somehow paradox, because the general perception is that flood runoff changes in the same percentage like precipitation although flood flow is not linearly correlated with precipitation but exponentially. Decreasing precipitation in the water-scarce stressed country, Jordan due to climatic changes, will have strong implications on rain-fed and irrigated agriculture and on household water supplies with very severe socio-economic percussions expressed in increasing unemployment and poverty which may lead to social and political unrest. Therefore, proactive measures have to be implemented before disasters hit. Such measures are limited in Jordan to seawater desalination, intensified water harvesting and improved water use efficiency in agriculture.

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.

Dynamic monitoring of surface water in the Tibetan Plateau from 1980s to 2019 based on satellite remote sensing images

The Tibetan Plateau is known as the“Asian water tower”,and changes in its surface water distribution are important indicators of global climate change and the regional response to these changes.Dynamic monitoring of the surface water on the Tibetan Plateau is an important part of the research on the functions of the“third pole”of the earth and the Asian water tower.With the support of the Google Earth Engine cloud platform,this study used a spectral index-based fast extraction method to obtain surface water data from multi-temporal Landsat(Landsat 4,5,and 8)satellite remote sensing images.Based on the extracted surface water data,we analyzed the spatiotemporal variations in the surface water of the Tibetan Plateau from 1980s to 2019.In this study,surface water area refers to the maximum coverage area of the surface water extracted from remote sensing images for one year,hereafter referred to as the surface water area.The results show that since 1980s,the overall surface water area of the Tibetan Plateau has increased,but not in a linear fashion.After a slight decrease from 1980s to 1995,the surface water area of the Tibetan Plateau increased steadily,except for a slight decrease in 2015,which may have been caused by the El Niño phenomenon.In terms of spatiotemporal distribution,different patterns exist in the various ecological regions of the Tibetan Plateau.The Inner ecological region had the greatest changes of surface water area among the ten ecological regions,accounting for 71.0%of the total surface water area increase from 1980s to 2019.The surface water bodies in the cold desert and the dry-winter subtropical climatic regions underwent the most changes,with their coefficients of variation being more than 20%.This study can provide data support for dynamic monitoring of surface water in the Tibetan Plateau.

Temporal and spatial evolution of surface sediments characteristics in the Dagu River estuary and their dynamic response mechanism

Based on the 39 surface sediment samples collected in the flood season and the dry season in 2012 respectively and the measured hydrological data in October 2012, the sediment grain size characteristics has been analyzed and the response mechanism of surface sediments to estuarine hydrodynamics was revealed by calculating the range of waves and tidal currents. The results show that:(1) The grain size of the surface sediment samples decreased gradually from land to sea in the flood season. The fine sediment was redistributed under marine hydrodynamics in the dry season and the sediments showed coarser tendency ingeneral;(2) tidal current stirring sediment was very obvious in Dagu River estuary area, and wave stirring sediments mainly occurred in the tidal flat area and estuary sand bar area;(3) in the flood season, surface sediment sat the estuary were transported towards south and southeast. In the dry season, surface sediments were transported towards southwest at the north area of Jiaozhou Bay Bridge, and sediments were transported towards northeast area at the south of Jiaozhou Bay Bridge.

Molecular dynamics study of room temperature ionic liquids with water at mica surface

Water in room temperature ionic liquids(RTILs) could impose significant effects on their interfacial properties at a charged surface. Although the interfaces between RTILs and mica surfaces exhibit rich microstructure, the influence of water content on such interfaces is little understood,in particular, considering the fact that RTILs are always associated with water due to their hygroscopicity. In this work, we studied how different types of RTILs and different amounts of water molecules affect the RTIL-mica interfaces, especially the water distribution at mica surfaces,using molecular dynamics(MD) simulation. MD results showed that(1) there is more water and a thicker water layer adsorbed on the mica surface as the water content increases, and correspondingly the average location of K^+ ions is farther from mica surface;(2) more water accumulated at the interface with the hydrophobic [Emim][TFSI] than in case of the hydrophilic [Emim][BF4] due to the respective RTIL hydrophobicity and ion size. A similar trend was also observed in the hydrogen bonds formed between water molecules. Moreover, the 2D number density map of adsorbed water revealed that the high-density areas of water seem to be related to K^+ ions and silicon/aluminum atoms on mica surface. These results are of great importance to understand the effects of hydrophobicity/hydrophicility of RTIL and water on the interfacial microstructure at electrified surfaces.

Surface Water Resources' Response to Climate Changes in Jilin Province

[Objective] The response of surface water resources on climate changes was studied.[Method] By dint of monthly average temperature and precipitation in 45 meteorological stations in Jilin Province from 1960 to 2000,monthly runoff in 56 hydrological stations in Songhuajiang and Liaohe region,the surface runoff change and the response of surface water resources to climate change in 41 years were expounded.[Result] The runoff of Songliao region was limited during 1960s and 1970s.It began to increase slowly in the early 1980s.Since 1990s,there were distinct fluctuation of annual runoff and it was decreasing in general.EOF analysis suggested that the runoff of Songliao region was decreasing gradually from south to the north.The central gradient was small and runoff was evenly distributed.MK test result showed that the annual runoff in Songliao region had large fluctuation before 1980s and after 1990s.The response of surface runoff on climate and precipitation changes in Jilin Province was distinct and had strong relevance as well as certain lagging.Based on the analysis of the relation of rivers runoff and meteorological elements changes,statistics forecast model between river surface runoff and meteorological elements was constructed.Runoff prediction value and measured value had good relation.The corresponding river surface runoff changes can be assessed based on the changes of meteorological elements.[Conclusion] The study provided theoretical basis for the development and utilization of surface water resources in Jilin.

Influencing factors of water resources in the source region of the Yellow River

Taking the source region of the Yellow River as a study area and based on the data from Madoi Meteorological Station and Huangheyan Hydrological Station covering the period 1955-2005, this paper analyses the changing trends of surface water resources, climate and frozen ground and reveals their causes. Results show that there exist frequent fluctuations from high to low water flow in the 51-year period. In general, the discharge has shown a de- clining trend in the 51 years especially since the 1990s. The annual distribution shows one peak which, year on year is getting smaller. （1） Precipitation has a significant and sustained influence on discharge. （2） A sharp rise of temperature resulted in the increase of evaporation and the decrease of discharge, which has a greater effect than on ice-snow melting. （3） Frozen ground tends to be degraded markedly. There is a significant positive correlation be- tween the permafrost thickness and the discharge. （4） Evaporation rates are significantly increasing, leading to the decrease of discharge. 70% of the discharge reduction resulted from climate change, and the remaining 30% may have been caused by human activities.

The Climate Change Impact on Russia’s Wind Energy Resource: Current Areas of Research

Exploration of the climate change impact on wind energy is a focus of scientific analysis and research in many countries around the world. Previous studies have demonstrated that over the last three decades measured wind in the boundary and surface layer of the atmosphere has changed all over the globe. However, effects of climate change on the wind energy sector of Russia are not well explored. Therefore, the Russian climate change research needs to focus on improving the analysis and prediction of wind characteristics that are most relevant to Russia’s wind energy development. This paper analyzes the effects of global climate change on the patterns of the general circulation of the atmosphere, large-scale atmospheric temperature field and dynamics, as well as wind speed in the planetary boundary layer and, in particular, in the atmospheric surface layer, with regards to Russia’s geographical location and its climatic characteristics. This paper also explores and discusses current areas of climate change research relevant for estimating the wind energy potential in Russia. Two areas of research are emphasized: study of the impact of global warming on poleward shifts of the large-scale synoptic eddies which strongly affect the weather patterns and wind field over large territories;and the study of the effects of ice melting in Arctic seas which significantly alter the properties of the underlying surface and, thus, speed and direction of wind in the surface layer.

Using Isotope Technology for Surface Water Environment Research in Southern Hanoi

The surface water in the southern of Hanoi capital is researched by identifying δ2H and δ18O stable isotopes together with EC, DO, BOD5, COD, TSS. Surface water samples for studying include the Red river, Nhue river and Kim Nguu river, Thanh Nhan lake, Yen So lake and Van Quan lake were collected in the dry season (April) and the rainy season (August) in 2015. The stable isotope analysis results showed that the δ18O values is a range from -42.53‰ to -64.05‰ and, the δ2H values is the range from -5.09‰ to -8.79‰ under global meteoric waterline (in the water vapor region). The δ2H results of the rivers and lakes in the dry season are more negative than the rainy season with a small difference. The δ18O results of lakes in the dry season are more negative than the rainy season, but the δ18O results of river in the dry season are more positive than the rainy season. The results of the EC, BOD, COD, DO, TSS analysis showed that surface water environment has changed clearly in the two seasons and the contamination level in the dry season is usually higher than the rainy season. The lakes and rivers strongly influenced by human activities led to seriously pollution are Van Quan lake and Yen So lake, Nhue river and Kim Nguu river.

Solution chemistry quasi-epitaxial growth of atomic CaTiO_(3)perovskite layers to stabilize and passivate TiO_(2)photoelectrodes for efficient water splitting

Perovskite oxides with unique crystal structures and high defect tolerance are promising as atomic surface passivation layers for photoelectrodes for efficient and stable water splitting.However,controllably depositing and crystalizing perovskite-type metal oxides at the atomic level remains challenging,as they usually crystalize at higher temperatures than regular metal oxides.Here,we report a mild solution chemistry approach for the quasi-epitaxial growth of an atomic CaTiO_(3)perovskite layer on rutile TiO_(2)nanorod arrays.The high-temperature crystallization of CaTiO_(3)perovskite is overcome by a sequential hydrothermal conversion of the atomic amorphous TiOx layer to CaTiO_(3)perovskite.The atomic quasi-epitaxial CaTiO_(3)layer passivated TiO_(2)nanorod arrays exhibit more efficient interface charge transfer and high photoelectrochemical performance for water splitting.Such a mild solution-based approach for the quasi-epitaxial growth of atomic metal oxide perovskite layers could be a promising strategy for both fabricating atomic perovskite layers and improving their photoelectrochemical properties.

中国生态环境质量现状及2016—2023年动态变化分析

以国家生态环境监测网数据为基础,分析2023年中国生态环境质量状况及2016年以来的变化特征。结果表明:2023年中国生态环境质量保持优良水平,其中,环境空气优良天数比例为85.5%,优良水质断面比例为89.4%,功能区声环境昼间和夜间达标率分别为96.1%和87.0%,生态质量指数为59.6;2016—2023年生态环境质量持续改善,其中,环境空气优良天数比例上升2.4个百分点,优良水质断面比例上升21.6个百分点,功能区声环境昼间和夜间达标率分别上升3.9个、13.0个百分点。但各生态环境要素质量在部分区域、特定时段不容乐观,京津冀及周边地区、汾渭平原空气质量总体水平仍低于全国平均水平,颗粒物和臭氧浓度偏高;个别流域仍为轻度污染,优良水质断面比例远低于全国水平,某些流域仍存在劣Ⅴ类水质断面,化学需氧量、总磷和高锰酸盐指数是地表水中的主要超标指标;声环境1类和4a类功能区夜间达标率仍相对较低;新疆中北部和甘肃西部地区仍有部分县域生态质量为四类或五类,生态脆弱的情况尚未得到根本改善。随着生态环境污染治理进入攻坚期,控制污染增量的边际成本增加,生态环境质量进一步改善的难度越来越大。

新疆空中水资源和地表水资源变化特征研究

大气降水是新疆一切水资源的根本来源,空中水资源是大气降水的物质基础,大气降水在当地形成地表水资源。水资源短缺是制约新疆经济社会高质量发展和生态安全保障的最关键自然因素。本文分析新疆空中水资源和地表水资源的变化特征,对新疆水资源系统规划和高效利用具有重要的科学意义。结果显示:1961—2022年新疆年降水资源量为2717.12×10^(8)m^(3),水汽输入量为21115×10^(8)m^(3),水汽净收支量为347.5×10^(8)m^(3),水汽降水效率为12.5%;2001—2021年新疆平均水资源总量为912.3×10^(8)m^(3),其中地表水资源量为864.1×10^(8)m^(3),产水系数为0.32。从变化趋势来看,1961—2022年新疆年降水量明显增加,新疆上空水汽总输入量和总输出量微弱减少,水汽净收支量微弱增加,水汽降水效率明显增加;2001—2021年新疆地表水资源处于丰水阶段,但产水系数有微弱的波动减小趋势。新疆水资源问题依然突出,在不同水资源精细化特征、不同相态水体转化关系等方面研究不足,未来需要加强研究以应对气候变化可能带来的新疆水资源安全风险。

佳木斯市2011年-2020年地表水生态环境质量变化研究

采用Spearman秩相关系数法,对松花江佳木斯市2011年-2020年期间主要污染指标变化趋势进行了分析。计算结果表明,2011年-2020年佳木斯上断面的高锰酸盐指数、化学需氧量、氨氮和总磷,佳木斯下断面的化学需氧量和总磷,江南屯断面的化学需氧量,同江断面的高锰酸盐指数、化学需氧量和总磷,汤旺河口内断面的化学需氧量、氨氮和总磷,梧桐河口内断面的化学需氧量和总磷呈显著下降趋势;其余监测断面的这几项监测指标无显著变化。对污染物的年际变化进行了分析,并探讨了地表水环境质量变化原因。

Projected changes in mean and interannual variability of surface water over continental China

Five General Circulation Model(GCM) climate projections under the RCP8.5 emission scenario were used to drive the Variable Infiltration Capacity(VIC) hydrologic model to investigate the impacts of climate change on hydrologic cycle over continental China in the 21 st century. The bias-corrected climatic variables were generated for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change(IPCC AR5) by the Inter-Sectoral Impact Model Intercomparison Project(ISIMIP). Results showed much larger fractional changes of annual mean Evapotranspiration(ET) per unit warming than the corresponding fractional changes of Precipitation(P) per unit warming across the country, especially for South China, which led to a notable decrease of surface water variability(P-E). Specifically, negative trends for annual mean runoff up to -0.33%/ year and soil moisture trends varying between -0.02% to -0.13%/year were found for most river basins across China. Coincidentally, interannual variability for both runoff and soil moisture exhibited significant positive trends for almost all river basins across China, implying an increase in extremes relative to the mean conditions. Noticeably, the largest positive trends for runoff variability and soil moisture variability, which were up to 0.41%/year and 0.90%/year, both occurred in Southwest China. In addition to the regional contrast, intra-seasonal variation was also large for the runoff mean and runoff variability changes, but small for the soil moisture mean and variability changes. Our results suggest that future climate change could further exacerbate existing water-related risks(e.g., floods and droughts) across China as indicated by the marked decrease of surface water amounts combined with a steady increase of interannual variability throughout the 21 st century. This study highlights the regional contrast and intra-seasonal variations for the projected hydrologic changes and could provide a multi-scale guidance for assessing effective adaptation strategies for China on a river basin, regional, or as a whole.

有自由面的裂隙网络稳定渗流试验与数值分析

为探究裂隙网络含自由面的稳定渗流特性,设计可视化的二维裂隙网络渗流试验装置,通过调节裂隙网络模型的上、下游水头开展一系列裂隙网络渗流试验,依次记录自由面水头高度和渗流流量大小;同时基于有限元软件COMSOL Multiphysics中的Darcy接口,建立等比例二维裂隙网络数值模型,复现试验工况并与试验结果对比分析。对比发现试验结果与模拟结果基本吻合,这验证了试验结果的有效性以及数值模拟的准确性。研究结果表明:影响自由面变化的主要因素为上、下游水头高度及二者高度差:渗流水力梯度越大,自由面位置的下降越快;渗流水力梯度相同的水力条件,上、下游水头越高,形成的自由面水头越高,自由面降落曲线也越陡。其中,若上、下游水头高度不处于近似的水平,二者对于自由面位置的影响存在较大差异。自由面变化的基本规律符合Dupuit公式的表述。稳定渗流的水力梯度与平均流量仅在流量较小时符合线性相关,随着水力梯度的增加,二者关系呈现明显的非线性。

基于Landsat TM/OLI影像的兖州煤田水域面积动态监测

为揭示东部高潜水位矿区地表水体的时空演变规律,该文以兖州煤田为研究区,在比较改进归一化差异水体指数法、单波段阈值法、谱间关系法、K-T变换4种水体提取方法的精度及优缺点基础上,采用基于阈值分割的改进的归一化差异水体指数法提取了研究区1990-2014年的水体信息并分析了其时空变化特征。研究结果表明:从1990-2009年,兖州煤田地表水域面积增加了1 696.14 hm^2,且2001-2005年水域面积扩张速度较快,年均增长率达14.0%,2009-2014年水域面积减少,年均下降率为3%;煤炭开采是研究区内水域面积变化的主要驱动因子。该文实现了煤矿区地表水体变化的动态监测,并分析了其变化原因,有助于客观与定量地评估煤炭开采的生态累积效应。