Hydrogeological Investigations of Groundwater and Surface Water Interactions in the Berg River Catchment, Western Cape, South Africa

The Berg River Catchment based in the Western Cape Province,South Africa services the greater Cape Town area with water,subsequent to supplying the vast agricultural activities that exist in the middle and the lower reaches.This study thus investigates the hydrogeochemical interactions between surface and groundwater in the Berg River Catchment with the aim of establishing trends and transfer of constituents between the surface and groundwater systems,investigates the role that geology plays in water chemistry as well as identifies the geochemical processes controlling surface and groundwater chemistry in the catchment.This study was carried out using three types of research designs namely i)experimental research design;ii)field research design and meta-analysis research design.Furthermore,the study made use of hydrochemical data ranging from 2003 to 2013 obtained from the National Water Monitoring Database owned and maintained by the Department of Water and Sanitation and data that were sampled in 2016 by authors and analyzed using the ICP-MS Technique Ground Water Chart,Arc-GIS and Geosoft(Oasis Montaj)were further employed to model the data.The results indicated that:i)in the Upper Berg there is not much interaction and transfer of constituents between surface and groundwater;ii)the Middle Berg,however,indicated a degree of interaction with the sharing of constituents between the two water systems and iii)the Lower Berg indicated only NaCl water type also noting that the area situated near the river mouth whereby there is the mixing of river and seawater.

Groundwater and surface water interactions in an alluvial plain, Tuul River Basin, Ulaanbaatar, Mongolia

Drinking water supplies in Ulaanbaatar, the capital of Mongolia, are completely dependent on groundwater sourced from pumping wells located in an alluvial plain of the Tuul River which flows through Ulaanbaatar. The interaction between groundwater in the alluvial plain and river surface water was investigated using a hydrological and multi-tracers approach. The observed groundwater contour map clearly shows that the Tuul River recharges the floodplain groundwater and groundwater flows from east to west. The similarity of chemical and stable isotopic compositions suggests that groundwater is mainly recharged by Tuul River water in the vicinity of the river. In addition, considering groundwater contours and chemical composition, groundwater in the northern and southern mountain sides contribute to floodplain groundwater. Stable isotopic information suggests that winter season precipita- tion also contributes to the groundwater, because groundwater in a specific region has a considerably lower isotopic ratio. Using the End Member Mixing Analysis applying oxygen-18, SiO2 and HCO3 as tracers, the contribution ratios of the Tuul River, groundwater in the northem and southern mountain regions, and winter season precipitation to floodplain groundwater are esti- mated to be 58% to 85%, 1% to 54%, 0% to 16%, and 0% to 12%, respectively.

The 2022 Extreme Heatwave in Shanghai,Lower Reaches of the Yangtze River Valley:Combined Influences of Multiscale Variabilities

In the summer of 2022,China(especially the Yangtze River Valley,YRV)suffered its strongest heatwave(HW)event since 1961.In this study,we examined the influences of multiscale variabilities on the 2022 extreme HW in the lower reaches of the YRV,focusing on the city of Shanghai.We found that about 1/3 of the 2022 HW days in Shanghai can be attributed to the long-term warming trend of global warming.During mid-summer of 2022,an enhanced western Pacific subtropical high(WPSH)and anomalous double blockings over the Ural Mountains and Sea of Okhotsk,respectively,were associated with the persistently anomalous high pressure over the YRV,leading to the extreme HW.The Pacific Decadal Oscillation played a major role in the anomalous blocking pattern associated with the HW at the decadal time scale.Also,the positive phase of the Atlantic Multidecadal Oscillation may have contributed to regulating the formation of the double-blocking pattern.Anomalous warming of both the warm pool of the western Pacific and tropical North Atlantic at the interannual time scale may also have favored the persistency of the double blocking and the anomalously strong WPSH.At the subseasonal time scale,the anomalously frequent phases 2-5 of the canonical northward propagating variability of boreal summer intraseasonal oscillation associated with the anomalous propagation of a weak Madden-Julian Oscillation suppressed the convection over the YRV and also contributed to the HW.Therefore,the 2022 extreme HW originated from multiscale forcing including both the climate warming trend and air-sea interaction at multiple time scales.

Understanding Surface Water-Groundwater Conversion Relationship and Associated Hydrogeochemistry Evolution in the Upper Reaches of Luan River Basin, North China

Luan River is the main water source in Beijing-Tianjin-Hebei region,northern China,where the groundwater system is vulnerable and pollution issue is serious.It is significant for regional groundwater resources protection to identify the hydrogeochemistry evolution and affecting factors along flow direction occurred in the upper reaches,especially the surface water-groundwater(SWGW)conversion relationship.In this study,recharge,conversion and geochemistry evolution of SW and GW were elucidated based on physical-hydrochemical indicators and stable isotopes in 36 GW samples and 20 SW samples,which were collected in July 2019 and July 2020.The factor analysis was further utilized to determine the main factors responsible for regional hydrogeochemical evolution.Results indicate that GW recharged SW in plateau area,and SW and GW recharged each other in typical Alpine valley area.The hydrochemical types are HCO3-Ca·Mg and HCO3-Ca,and the hydrochemical evolution is dominated by weathering of silicate and carbonate minerals.The cation exchange adsorption has minor impact on groundwater hydrochemistry.The rise of SO42-and NO3-contents in groundwater is related to industrial and agricultural activities.The main controlling factors of SW hydrochemical components included recharge from groundwater,industrial and mining activities,explaining 90.04%of data variance.However,water-rock interaction,agricultural and domestic sewage are responsible for GW quality,accounting for 83.38%.

Sediment Transport Capacity Under the River–Tide Interaction in the Changjiang Estuary

Sediment transport capacity is a fundamental parameter in sediment transport theory and its accurate calculation is important from both theoretical and engineering viewpoints. The capacity of sediment transport has been studied extensively by many researchers in the last decades. Nevertheless, the underlying mechanism behind sediment transport capacity in estuaries remains poorly understood. The current study aims to explore the impact of the river–tide interaction on sediment transport and establish a formula of sediment transport capacity under the river–tide interaction. The impact of the river–tide interaction on the hydrodynamics and sediment dynamics in the Changjiang Estuary was analyzed, a practical method for describing the variation in tide-runoff ratio was established,and a formula of sediment transport capacity considering the impact of river–tide interaction was proposed by introducing the tide-runoff ratio. The new method bridged the gap between two well-known sediment transport capacity methods by considering the variation in the index a for the gravitational term and overcomes the drawback of distinguishing flood/dry season or spring/ebb tide in the calculation of estuarine sediment transport. A large amount of flow and sediment data obtained from the Changjiang Estuary were collected to verify the proposed formula. The effect of salt-fresh water mixture and the morphological evolution on sediment transport capacity of the Changjiang Estuary were discussed.

INFLUENCE OF SEA－AIR INTERACTION ON THEDISCHARGE OF FLOOD SEASON IN THEUPPER REACHES OF THE CHANGJIANG RIVER

On the method of correlation analysis the poper begins with searching theSST (Sea Surface Temperature) and circulation features of some regions with close correlation to the discharge of the flood season (from June to September) in the upperreaches of the Changjiang (Yangtze) River, then discusses the characteristics of sea-airinteraction and the relations between the sea-air interaction and the discharge of theflood season,after that analyzes the possible mechanisms through which the main searegions affect atmospheric circulation, and of the influence of the circulation changes onthe discharge of the flood season.

The curve of ion exchange ratio(%)-pH of the interaction between suspended particles with Cd(Ⅱ) in the Yellow River

The curve of ion exchange ratio(%) pH of the interaction between suspended particles with Cd(II) in the Yellow River was studied. The effects of lysine on this curve have been also investigated. The results showed that (1) Cadmium in Cd(OH) + form in the suspended particles exchanges with the cations. The exchange ratio of Cd 2+ is nearly at its greatest value in the range of pH (8.0—8.5) in natural aquatic system; (2) Ion exchange ratio decreases as the concentration of Cd 2+ raises from 8.9×10 -6 mol/L to 2×8.9×10 -6 mol/L; (3) At the lysine concentration of 6 8×10 -6 mol/L, it can promote the ion exchange ratio; (4) Adsorption of the suspended particles to cadmium is weaker in seawater and Jin Sha River than in the Yellow River.

Dataset of Comparative Observations for Land Surface Processes over the Semi-Arid Alpine Grassland against Alpine Lakes in the Source Region of the Yellow River

Thousands of lakes on the Tibetan Plateau(TP) play a critical role in the regional water cycle, weather, and climate. In recent years, the areas of TP lakes underwent drastic changes and have become a research hotspot. However, the characteristics of the lake-atmosphere interaction over the high-altitude lakes are still unclear, which inhibits model development and the accurate simulation of lake climate effects. The source region of the Yellow River(SRYR) has the largest outflow lake and freshwater lake on the TP and is one of the most densely distributed lakes on the TP. Since 2011,three observation sites have been set up in the Ngoring Lake basin in the SRYR to monitor the lake-atmosphere interaction and the differences among water-heat exchanges over the land and lake surfaces. This study presents an eight-year(2012–19), half-hourly, observation-based dataset related to lake–atmosphere interactions composed of three sites. The three sites represent the lake surface, the lakeside, and the land. The observations contain the basic meteorological elements,surface radiation, eddy covariance system, soil temperature, and moisture(for land). Information related to the sites and instruments, the continuity and completeness of data, and the differences among the observational results at different sites are described in this study. These data have been used in the previous study to reveal a few energy and water exchange characteristics of TP lakes and to validate and improve the lake and land surface model. The dataset is available at National Cryosphere Desert Data Center and Science Data Bank.

Soil-vegetation-atmosphere interaction over a hilly forest in the southern Huaihe River Basin:Long-term field experiment and preliminary analysis of basic observations

To improve the understanding of the CO_(2) exchange and the cycling of energy and water between the land surface and atmosphere over a typical hilly forest in southeastern China,a long-term field experimental observatory was established in Huainan,Anhui Province.Here,the authors briefly describe the three parts of ongoing research activities:the environmental monitoring at the site,the meteorological observations on a high tower,and particularly the intensive measurement of soil-vegetation-atmosphere interaction on a lower tower.Specifically,the diurnal variation of basic meteorological variables on a typical clear day(13 July 2018),and their temporal variation in the first three months of the low tower’s operation(4 June to 31 August 2018),and in combination with simultaneous data from the high tower,are analyzed.Results show that the data demonstrate reasonable variabilities,and the variables exhibit significant diurnal variation,characteristics of summer values,and considerable differences in summer months.The daily and monthly average albedos above the forest canopy were both 0.13.The daily average soil CO_(2) concentration was 1726 and 4481 ppm at 2 and 10 cm,respectively.The soil CO_(2) concentration changed with soil volumetric moisture contents,but showed a weak correlation with soil temperature in summer 2018.As the observatory continues to run and data continue to be collated,further investigation of the long-term variation of monsoon characteristics should be performed in the future.The experiment is useful in ecosystem and atmosphere interaction research,as well as for the development and evaluation of climate models,in the transitional climate zone of the Huaihe River basin.

黄河流域生态系统服务供需的时空变化及与人类活动的空间交互作用

【目的】随着人类活动对生态系统干扰的日益加强,分析黄河流域生态系统服务供需的变化特征及其与人类活动的交互作用,能够为生态保护和可持续发展策略的制定提供理论依据。【方法】采用当量因子法核算1980—2020年黄河流域生态系统服务供给量,以土地利用开发程度、人口密度和经济密度核算生态系统服务需求量,并基于供需分析和人类活动强度的量化结果,采用双变量空间自相关分析方法揭示了两者之间的交互关系。【结果】结果表明:1980—2020年,黄河流域生态系统服务供给呈现先减少后增加趋势,总体减少了14.43×10^(8)元;生态系统服务需求增加,特别是在2000年后增加更明显,2020年呈现自西向东递增的空间格局。黄河流域低供给-高需求的地级市主要位于研究区东部地区,低供给-低需求的地级市主要位于中部地区且被高供给-低需求的地级市围绕。人类活动强度呈现东部地区较高,而西部地区较低的特征,且随时间推移在增强。黄河流域生态系统服务供需与人类活动强度之间表现为显著的空间负相关性,并且在局部尺度呈现出High-Low集聚、Low-High集聚和Low-Low集聚三种集聚模式。【结论】研究结果可视化了黄河流域生态系统服务与人类活动在空间上的权衡关系,能够为协调生态保护与人类活动的政策制定提供科学指引。

The Relationship between Water Resources Use Efficiency and Scientific and Technological Innovation Level: Case Study of Yangtze River Basin in China

The Yangtze River Basin’s water resource utilization efficiency(WUE)and scientific and technological innovation level(STI)are closely connected,and the comprehension of these relationships will help to improve WUE and promote local economic growth and conservation of water.This study uses 19 provinces and regions along the Yangtze River’s mainstream from 2009 to 2019 as its research objects and uses a Vector Auto Regression(VAR)model to quantitatively evaluate the spatiotemporal evolution of the coupling coordination degree(CCD)between the two subsystems of WUE and STI.The findings show that:(1)Both the WUE and STI in the Yangtze River Basin showed an upward trend during the study period,but the STI effectively lagged behind the WUE;(2)The CCD of the two subsystems generally showed an upward trend,and the CCD of each province was improved to varying degrees,but the majority of regions did not develop a high-quality coordination stage;(3)The CCD of the two systems displayed apparent positive spatial autocorrelation in the spatial correlation pattern,and there were only two types:high-high(H-H)urbanization areas and low-low(L-L)urbanization areas;(4)The STI showed no obvious response to the impact of the WUE,while the WUE responded greatly to the STI,and both of them were highly dependent on themselves.Optimizing their interaction mechanisms should be the primary focus of high-quality development in the basin of the Yangtze River in the future.These results give the government an empirical basis to enhance the WUE and promote regional sustainable development.

黄河下游典型悬河段地表水-地下水对湿地形成条件影响

对比分析黄河下游径流及河道变迁特征、不同时期地下水流场特征,结合遥感解译手段解析地下水和地表水对沿黄湿地条件的影响,为该区湿地生态修复提供理论依据。结果表明:(1)黄河下游典型悬河段人工湿地面积增幅较多,自然湿地仍呈萎缩趋势,滩涂湿地破碎度上升,生态环境稳定性较差。(2)地表水流量和水位整体呈现逐年降低的趋势,且河道的游荡摆动依然明显,直接影响了河流滩涂湿地面积及其稳定性。(3)研究区浅层地下水位十余年最大下降5 m、二十余年最大下降9 m。浅层地下水的持续下降导致北岸堤外湿地面积减少;南岸堤外因引黄水和退水侧渗形成新的背河洼地,湿地面积呈增长趋势,生态环境稳定性相对较好。地表水和地下水连通性较好,较低的地下水位将会削弱河道径流的作用,对沿黄湿地整体发展不利。(4)减少地下水的开采,确保引黄水量充足,对黄河大堤外背河洼地部位湿地的发展有利。

黄河三角洲地面沉降研究进展与未来展望

黄河三角洲是我国成陆时间最短的大型河口三角洲,由于其发育背景特殊、地质环境系统不稳定以及人类活动影响,地面沉降较为显著,引发了诸多环境问题,对自然环境和社会经济发展产生了严重威胁。从监测技术和成因机理角度出发,系统综述了黄河三角洲地区的地面沉降现状:(1)黄河三角洲地面沉降受新生地层自然压实、人为建筑重力压实、河流陆源输入减少、地下水与卤水开采、石油天然气开采以及海洋动力作用相对增强等多重因素影响,需要更详细、更系统地研究,特别是定量分离人为与自然因素在地面沉降的贡献方面,需要与其他学科如地质、岩土、力学、数学等交叉进行综合定量分析;(2)黄河三角洲地面沉降的长时空尺度的持续监测与分析、历史周期分析与未来判断分析需加强,尤其要重视海陆相互作用对地面沉降的长期和短期影响的研究;(3)地面沉降勘查、监测和精度研究及沉降评估和环境影响监测研究,尤其是海岸带退蚀与地面沉降之间的耦合关系等问题仍待深入。在今后研究黄河三角洲地面沉降的过程中,应更加注重理论模型的深入探究和新技术方法的实践,机理研究应扩展至多种模型研究;预测灾害时,应扩展到与地面沉降问题较为紧密的地面开裂、断层以及地裂缝等研究上。此外,还应对地面沉降的社会经济影响和环境影响等方面做出更多探索和实际应用。全面系统深入地了解黄河三角洲地面沉降现象,可为有效地实施三角洲生态保护和资源开发提供理论依据,具有重要的科学意义和社会经济价值。

水资源约束下黄河流域水城互馈机制与调适路径研究

黄河流域在我国经济社会发展和生态安全方面具有十分重要的地位,但是水资源保障形势严峻,已经是黄河流域城市发展的最大刚性约束。在水资源约束下,水城之间的互动反馈机制作用乘数放大,胁迫、优化、增长、收敛等效应复合发力,水城关系的复杂性、矛盾性、可变性等明显增强。贯彻落实黄河流域生态保护和高质量发展战略,推进水城协调发展,要坚持系统观念,完善约束倒逼和挖潜提升、系统治理和水沙关键、流域统筹和因城施策、市场调节和政府调控相结合的调适路径。

旅游产业集聚与旅游生态安全的互动关系研究——以长江中游城市群为例

系统审视旅游产业集聚与旅游生态安全的互动关系对促进旅游高质量发展与生态可持续性发展具有重要意义。以长江中游城市群的26个城市为研究对象,基于区位熵和模糊物元模型分别测度2010—2021年各城市旅游产业集聚水平和旅游生态安全,并运用PVAR模型探讨旅游产业集聚与旅游生态安全的互动关系。研究结果表明:时间序列上,长江中游城市群旅游产业集聚水平和旅游生态安全整体呈现稳步上升的态势,旅游产业集聚水平的区域差异随时间变化不断提升,而旅游生态安全的区域差异则不断下降。空间分布上,长江中游城市群旅游产业集聚中高水平区占据主导地位,呈现出“环鄱阳湖城市群>环长株潭城市群>武汉城市圈”的格局;旅游生态安全呈现出以武汉市、南昌市与长沙市为主的“三足鼎立”的分布格局。长江中游城市群旅游产业集聚和旅游生态安全存在显著的互促关系,方差分解结果表明,旅游产业集聚和旅游生态安全受自身影响最大,且旅游产业集聚对旅游生态安全的影响远大于旅游生态安全对旅游产业集聚的影响。

黄河流域绿色发展效率与产业结构升级空间交互溢出效应

为了给黄河流域绿色发展、产业结构升级和高质量发展提供参考,运用超效率SBM模型和核密度估计法对黄河流域2006—2020年70个地级市的绿色发展效率进行测算,并基于广义三阶段空间最小二乘法建立绿色发展效率、产业结构升级空间计量模型,研究产业结构升级与绿色发展效率的空间交互溢出效应,主要结论如下:1)黄河流域绿色发展效率在研究时段内整体上呈波动上升趋势,从空间上看在研究时段初区域差别较大、在研究时段末各区域趋于一致;2)从流域整体上看,绿色发展效率与产业结构升级存在互促效应,其中产业结构升级对绿色发展效率的促进效应更为明显,且二者之间存在空间交互溢出效应,即以地级市为样本的绿色发展效率受周边地区绿色发展效率和产业结构升级的正向影响,但产业结构升级受周边地区绿色发展效率的负向影响;3)分区域看,绿色发展效率与产业结构升级之间的关系存在区域异质性,上游地区二者互促但中下游地区二者互抑,二者对绿色发展效率的空间交互溢出效应在上、中、下游地区均表现为正向;4)绿色发展效率还受经济发展水平、城镇化水平、科技创新、人口规模、对外开放水平、环境规制强度、政府行为、城市交通基础水平等因素的影响。

黄河流域数字经济与高质量发展耦合互动关系研究

为了厘清黄河流域数字经济与高质量发展现状、探究二者的耦合协调与互动关系,进而为黄河流域生态保护和高质量发展战略的实施提供参考,从理论上分析了黄河流域数字经济与高质量发展之间的互动机制,基于黄河流域64个地级市(州)2011—2020年的面板数据,测度了数字经济发展水平与高质量发展水平,运用耦合协调度模型实证分析了二者之间的耦合协调关系,并利用PVAR模型探究数字经济与高质量发展的互动关系。主要结论如下:1)黄河流域数字经济发展水平在研究期有所提升,但仍普遍较低且存在明显的地区差异,具有东高西低特征,呈现分别以济南、郑州、西安、太原、呼和浩特为核心的圈层状分布格局;2)黄河流域高质量发展不平衡问题突出,存在两极分化的情况,呈现明显的圈层结构,形成了分别以济南、郑州、太原、西安、兰州等省会城市为核心的高质量发展水平高值区;3)黄河流域数字经济与高质量发展耦合协调度逐年上升,但协调水平整体上还较低,当前仅实现了由轻度失调水平向濒临失调水平的跨越,耦合协调度在空间上呈现下游>中游>上游的特点;4)黄河流域数字经济与高质量发展均具有较强的自我依赖性,高质量发展对数字经济发展的促进作用较为明显,而数字经济发展对高质量发展的推动作用有待加强。

河流分类分级分段及河流形态学研究进展

河流分类、河流分级及干流河道分段合称为河流三分(分类·分级·分段);基于河流三要素(流域-水系-干流河道)和河流三分-河流形态学-河流学体系,开展了河流三分理论研究及实践应用、河流形态学再构建以及河流形态定性特性与定量因子指标辨识。主要成果结论包括:①优化了独立与非独立河流分类、河流分级Horton法改进、河流5区分段等方法,完善了河流界定拓展、河流平等与分级、干流河道“层次分段”等新理论,总结了世界大江大河及长江河流三分实践应用;②河流形态学研究河流现状及恒常形态,包括以河流三分为基石的河流三要素特性研究和以干流河道平面-剖面-断面形态为核心的河谷-河床-河道形态研究;③定性辨识了河流形态15项殊相特性与共相原则(包括复合流域水系、复杂干流河道等形态特性,干流河道优先、河流湖泊统一、干流河道唯一、侵蚀基面统一等新增原则);④定量辨识了河流形态4类因子指标,双指标3种相关关系(并行-从属-或然)与3类组合模式(物理-化学-生物)以及三因子4类及9种相关模式(均衡线型-瓶颈线型-三角形-金字塔-均分圆-同心圆-同切圆-交叉圆-三角圆)。倡导“河流学-长江学-水科学”学科范式,积极践行“治河·治江·治水”理念。

漓江流域喀斯特综合干扰评价及其空间特征

喀斯特地区具有特殊的地质结构,生态环境脆弱性较高,辨识和量化人为、自然多重干扰是减少人类干扰影响及制定喀斯特景观管理政策的重要依据。基于漓江流域喀斯特发育地貌特征,旨在建立包括地貌、水文、气候、生物、社会5类因素以及15个具体干扰指标的喀斯特综合干扰指数,并通过空间相关分析探究地理因子对综合干扰解释力以及因子与指标间交互作用力的特征。结果显示:(1)漓江流域中游综合干扰指数高于上下游,自然地形地貌本底以及不同类型喀斯特景观分布的地带性是分异的主要原因;(2)干扰等级为显著干扰,综合干扰指数为0.336,空间上呈现出东部与北部低、西部与南部高的分布特征,具有明显的空间异质性;(3)地理环境和社会经济因素对综合干扰具有较强解释力,采石采矿、各类灾害、生产活动等多项干扰指标以及海拔高度具有较强空间关联关系。评估了漓江流域喀斯特综合干扰并分析其空间特征,研究结果对喀斯特生态环境保护及景观资源可持续发展政策制定具有重要参考价值。