Reservoir dam safety has a bearing on the effectiveness of reservoirs in flood control, power generation and irrigation, as well as the safety of people's lives and property. Reservoir dam failure flood analysis can provide important technical support for reservoir flood control and rescue planning, risk management, disaster assessment and so on. In this paper, the HEC-RAS model was used to simulate the instantaneous dam failure flooding process under different scenarios, and to obtain important water information such as downstream inundation time, scope, and depth, etc, taking the Wanmipo Hydropower Station as an example. It was found that the fastest flows in the inundation zone channel and near the reservoir were of high risk, and that the effects of the different dam failure scenarios on the flood flow at each section were significantly different due to the differences in the incoming flow and initial downstream river level. Based on the differences in flood depth and flow rate, different hazard values were assigned to assess the risk of dam failure, taking into account the loss of life of the population, and it was found that the time for population transfer and resettlement should be within 6h, and the earlier the warning was given, the smaller the loss of life caused by dam failure would be, with 3h as the optimal warning time. This study provided data reference and technical support for downstream flood control decision-making, and also provided reference for other large and medium-sized reservoir project dam failure analysis.

The Key counties and towns are the focus areas of investigation and evaluation of mountain flood disasters at this stage. The research of flood inundation analysis conducted on the Key counties and towns is beneficially promoted to scientifically guide the prevention and control of mountain flood disasters. Taking the Xinglong Community in Guanba Town, Chongqing City as the research object, this study carried out the flood inundation simulation based on the HEC-RAS two-dimensional unsteady flow model, and this simulation results were compared with existing research findings. The 5-year, 20-year, and 100-year flood inundation risk maps were drawn by the ArcGIS, and the corresponding disaster situations were counted. The results indicated that the HEC-RAS model was reasonable and effective for flash flood inundation simulations, flash flood warnings, and flood prevention and disaster mitigation in urban and rural areas.

In this study, the stable isotopic and hydrochemical composition of surface water is systematically investigated to reveal the potential sources, influencing factors and chemical weathering processes. Results show that the primary recharge source of surface water is local precipitation, and its isotopic composition influenced by both evaporation effects and altitude effects. Multiple factors can affect the major ion composition in surface water, including the atmospheric precipitation, anthropogenic input, and rock weathering. The average contribution rates from each endmember are 7.17

Danjiangkou Reservoir has been widely concerned as the water source of the world’s longest cross basin water transfer project. Biogenic elements are the foundation of material circulation and key factors affecting water quality. However, there is no comprehensive study on the biogenic elements in tributaries of Danjiangkou Reservoir, hindering a detailed understanding of geochemical cycling characteristics of biogenic elements in this region. Guanshan River, one of the main tributaries that directly enter the Danjiangkou Reservoir, was token as the research object. Spatiotemporal distribution characteristics of basic water quality parameters and biogenic elements were studied. Water quality was comprehensively evaluated through water quality index (WQI). Absolute principal component score-multiple linear regression (APCS-MLR) model was adopted to explore the main sources of biogenic elements. Results showed that, in terms of season, the concentrations of total nitrogen (TN), total phosphorus (TP), and dissolved organic carbon (DOC) were significantly higher in wet season than in dry season, while no significant differences were found for dissolved inorganic carbon (DIC) and dissolved silica (DSi). Spatially, the concentrations of dissolved carbon, DIC, TN, and TP in the middle and lower reaches were higher than that in the upstream. DOC concentration peaked in the middle reaches, while DSi showed higher concentrations in the upstream. WQI values indicated that the river water quality was between good and excellent, although the water quality in wet season was slightly worse than that in the dry season. PCA extracted five potential sources, which accounting for 84.12

Estuaries are generally considered to be important sources of atmospheric CO2. However, the differences between estuaries, and inadequate observations of partial pressure of CO2 in estuarine water (pCO2water) hamper global estuarine CO2 budgeting. In this study, the longitudinal distribution of CO2 in the waters of Modaomen (MSE) and Lingdingyang (LSE), two sub-estuaries of the Pearl River Estuary (PRE), and its influencing mechanism are studied. The change in the distribution of pCO2water along the distance from the upstream estuary to the ocean between LSE and MSE was significantly different. pCO2water at the LSE ranges from 238 to 7267 µatm, whereas the MSE ranges from 406 to 3078 µatm. Stronger microbial respiration and relatively long water retention times were the main influences that led to higher pCO2water at LSE than at MSE. Seasonally, the increase of soil CO2 into the water in the upstream basin caused by precipitation is the potential influencing factor that the water pCO2water in the flood season is higher than in the dry season. PRE was a net source of atmospheric CO2 with an average annual water–air flux of 41.2 ± 33.3 mmol m−2 day−1. Our results suggest that the differences in longitudinal gradients of pCO2water between estuaries in the same region and the effects of different gas transport velocity models on CO2 emission estimates need to be considered in estuarine CO2 emission budgeting.

为实现山洪灾害危险区分区、分级及精细化管理,结合危险区实际,在已有成果基础上开展山洪灾害危险区动态调整工作十分必要.以重庆市山洪灾害危险区管理为例,在现有技术标准、管理指南以及管理现状基础上,归纳了危险区管理原则,制定了危险区动态管理清单编制流程,设置了危险区调整变更条件,提出了基于FloodArea模型的危险区防洪能力确定思路,细化了危险区等级划分标准,总结了危险区预警阈值计算方法.实践表明,该管理办法符合重庆市山洪灾害防御实际,可用于防洪减灾管理工作.研究成果以期为提升山洪灾害防御能力,完善山洪灾害防御体系提供支撑.

基于2013-2015年和2016-2019年2个阶段历史山洪灾害调查成果,分析了重庆市境内有历史记录的831次山洪灾害时空分布特征,利用ArcGis中的重力模型、标准差椭圆模型研究山洪灾害空间变化规律,并通过地理探测器模型开展了驱动因素分析.分析和研究结果表明:①从山洪灾害频次历年分布来看,重庆市历史山洪灾害大体分为3个阶段:受历史山洪灾害文献记录所限,1926-1977年和1977-2006年期间分别为灾害发生的低频期和低频波动期;随着极端暴雨事件和社会经济快速发展,2006-2017年期间为灾害发生的高频波动期,同时小波分析显示灾害频次呈3.7 a的周期变化.②从山洪灾害造成的死亡、失踪人员来看,2000年以后,尽管灾害频次不断上升,但因灾死亡、失踪人数趋于平稳,体现了山洪灾害防治措施发挥了效益.③5月份重庆地区灾害重心在渝东南彭水、武隆一带,6月份灾害重心向北迁移,进入7月份以后,灾害重心向渝西地区迁移,随后8-9月份,灾害逐渐转向渝东北.④地理探测器模型分析显示,河网密度和高程因子对山洪灾害解释程度较好,各因子两两叠加后,解释力均呈非线性增强.重庆市历史山洪灾害规律的研究成果有助于认清重庆市山洪灾害时空演变格局及驱动因素,可为山洪灾害防治工作提供技术支撑与理论指导.

To explore the causes of the “2020·6·12” flash flood disaster in Zheng’an County, Guizhou Province, data was collected and site surveys were conducted. The disaster, flood and rain conditions were analyzed. The dynamic process of flood inundation was simulated and verified using two-dimensional flow model software based on two-dimensional shallow water equations. The causes of the flash flood disaster were obtained: 1) The special topography provided basic conditions for the disaster; 2) Short-duration heavy rainfall superimposed on high previous cumulative rainfall was the key factor in inducing disaster; 3) The contradiction between the inadequate flood control capacity of the river course and excessive peak discharge made disasters inevitable; 4) Many non-residents and floating population, women and children with poor self-rescue ability, and people with low risk-avoidance awareness greatly increased disaster risks. On this basis, some measures to prevent and control flash flood disasters were proposed such as scientific top-level design, improvement of mass monitoring system and prevention of flash flood disaster, and detailed dynamic management of flood control and disaster reduction.

The water-level fluctuation zone of the lower Jinsha River Basin is a fragile ecosystem with limited water resources in the southwest of China. Soil water is critical for maintaining ecological balance and promoting the healthy development of animals and plants in this region. In this study, eight typical soil profiles were monitored for hydrochemistry in soil-soluble salt from upstream to downstream of the lower Jinsha River Basin. The results show that the soil water content was low and had a negative correlation coefficient with major ions in the soil-soluble phase. The soil-soluble salt is slightly alkaline, and Ca2+, Na+, SO42−, and HCO3− are important components for ions in a soluble phase. Major ions in soluble salt originate from various sources, including precipitation, anthropogenic input, silicate weathering, and carbonate weathering, and the contribution rates from each end member were 0.7%, 45.1%, 25.2%, and 29%, respectively. The ion composition in surface soil soluble salt is mainly influenced by precipitation and human activities, while the ions in the 0–50 cm soil layer originate from the precipitation input and water-rock interaction. In addition, rock weathering is a vital process for releasing ions into soil-soluble salt from 50 to 100 cm soil layer. Our findings provide important references for ion sources and the eco-hydrological process in limited water resources in the water-level fluctuation zone of the lower Jinsha River Basin.

Riverine dissolved matter reflects geochemical genesis information, which is vital to understand and manage the water environment in a basin. The Ganjing River located in the hinterland of the Three Gorges Reservoir was systematically investigated to analyze the composition and spatial variation of riverine ions, probe the source and influencing factors, and assess the chemical weathering rates and CO2 consumption. The results showed that the total dissolved solid value (473.31 ± 154.87 mg/L) with the type of “HCO3−–Ca2+” was higher than that of the global rivers’ average. The hydrochemical parameters were relatively stable in the lower reservoir area of the Ganjing River, which was largely influenced by the backwater of Three Gorges Reservoir. The carbonate weathering source contributed 69.63% of TDS (Total dissolved solids), which generally dominated the hydrochemical characteristics. The contribution rates of atmospheric rainfall were relatively low and stable in the basin, with an average of 4.01 ± 1.28%. The average contribution rate of anthropogenic activities was 12.05% in the basin and even up to 27.80% in the lower reservoir area of the Ganjing River, which illustrated that the impoundment of Three Gorges Reservoir had brought great challenges to the water environment in the reservoir bay. The empirical power functions were tentatively proposed to eliminate the dilution effect caused by runoff discharge on the basis of previous studies. Accordingly, the rock weathering rate was calculated as 23.54 t/km2 in the Ganjing River Basin, which consumed atmospheric CO2 with a flux of 6.88 × 105 mol/y/km2. These results highlight the geochemical information of tributaries in the hinterland of the Three Gorges Reservoir, have significant implications for understanding the impact of impoundment, and provide data support for the integrated management of water resources in the Ganjing River Basin.

巴丹吉林沙漠东南部湖泊群是该沙漠重要的水源之一,为揭示湖泊群水体潜在补给来源和补给方式,探索湖泊水体离子空间变化特征及其影响因素,系统分析了该沙漠东南部湖泊群水体δ18 O和δD同位素特征及水化学组成.结果表明:①巴丹吉林沙漠湖泊群水体pH和电导率平均值分别为9.29,291 mS/cm,以Na+和Cl-离子为主,占离子总量比例达69.4％.② 湖泊群水体 δ18 O和 δD同位素平均值分别为6.42‰和-3.67‰,不同区域湖泊群蒸发效应差异显著,湖泊蒸发强度自东南部至西北部逐步增大.③ 基于同位素高程效应方程,研究区湖泊水体潜在补给来源为东南部雅布赖山大气降水,补给方式主要以周边地下水侧向补给为主.补给水源和区域岩石风化是研究区湖泊群水体离子空间变化的主控因素.

干旱沙漠区水资源是改善生态环境和促进动植物生存的关键.综合古尔班通古特沙漠研究成果,分别对该沙漠气候特征、水分分布和水分来源、水分循环和生态水文过程等方面进行归纳,指出现有研究存在的不足.在此基础上对古尔班通古特沙漠今后研究的方向和内容进行展望,指出将该沙漠不同水体纳入整体研究,以期丰富该沙漠生态水文机制和进一步探讨干旱区水文循环过程.

为探究土壤CO2浓度变化特征及其对岩溶碳循环的影响,于2018年6—12月对重庆市南川区后沟泉水化学及泉域上覆土壤CO2(监测点土地利用类型为玉米-油菜轮作地)进行为期7个月的连续监测和采样,并结合1—5月的监测数据,定量分析旱雨季土壤CO2浓度与岩溶碳汇量的季节性演变特征及二者的相互关联性.结果表明:①土壤CO2浓度具有显著的季节性变化特征,主要表现为雨季较高、旱季较低,其最高值和最低值分别出现在9月(13316μmol/mol)和1月(2262.63μmol/mol).②温度与土壤CO2浓度之间存在较强的正相关关系(R2=0.82,0.0010.5),说明土壤CO2浓度主要受温度的影响.③泉水Ca2++Mg2+、HCO3?浓度在雨季明显高于旱季,而水体CO2净消耗量在旱雨季无较大差异,这可能是由于受土壤CO2效应、降水稀释效应和H2SO4/HNO3释放CO2的共同影响.研究显示,土壤CO2浓度的变化特征表现为季节性差异,但在土壤CO2浓度及外部环境的多重影响下,岩溶碳循环的季节性变化并不明显.

洪涝灾害是制约我国社会经济可持续发展的重要灾害.洪涝灾害评估研究是实现其有效防治的重要依据.本文根据《洪涝灾情评估标准》(SL 579—2012),选择死亡人口、受灾人口、农作物受灾面积、直接经济损失、水利设施经济损失、倒塌房屋、骨干交通中断历时、城市受淹历时、生命线工程中断历时等内容作为评估指标,以2017年度重庆市洪涝灾害作为研究对象,探讨境内暴雨洪灾分布规律.研究结果显示,2017年重庆市境内发生的13次区域性暴雨和1次局部暴雨,共计造成1.41×106人受灾,直接经济损失1.594×109元,其中,9月洪涝灾害损失最为严重.从受灾区域分布来看,渝东北开州、万州、巫溪等区(县)损失严重,渝西部地区灾害损失相对较轻.从场次洪涝灾害和年度洪涝评估结果来看,2017年属一般洪涝灾害年.本研究可为洪涝灾害评估提供方法借鉴,为暴雨洪灾防御工作提供数据与理论支撑.

为分析不同降水条件下岩溶泉水化学性质的变化特征及影响机制,本研究于2020年10月7日和2020年10月31日对重庆南山8个岩溶泉进行了对比监测.结果显示:相对于7日,31日各监测点的水温和溶解氧均表现为下降趋势,而pH均表现为上升趋势,但各监测点电导率、HCO3-浓度的变化特征却并不相同;各监测点溶解无机碳的稳定碳同位素(δ13CDIC)均表现为31日偏正于7日,氘同位素(δD)和氧同位素(δ18O)也均表现为31日偏正于7日,且各监测点氘盈余(d-excess)均表现为31日大于7日.这说明31日降水减少,增加了水岩接触时间,同时,泉水出露后在岩溶潭中滞留时间也随之增加,水体CO2脱气作用加剧,进而使部分监测点的电导率及HCO3-浓度降低.

地球表层元素硅（Si）的生物地球化学循环影响全球初级生产力和全球碳循环进而影响地球环境变化。土壤生物硅（BSi）因其易溶解而成为岩石圈-土壤圈-生物圈-水圈等圈层之间Si迁移-转化的枢纽。采集海南岛西南部的热带季雨林、经济林（橡胶林、桉树林、芒果林）和农作物（香蕉、甘蔗）土壤样品。采用热碱消化连续提取法萃取BSi;运用相关分析和主成分分析法识别土壤BSi含量变化的主要驱动因素。结果表明：研究区不同植物群落土壤BSi含量从大到小依次为：香蕉地（（2.38±0.72）mg/g）＞热带季雨林（（1.86±1.34） mg/g）＞橡胶林（（1.42±0.81） mg/g）＞桉树林（（1.22±0.28） mg/g）＞芒果林（（0.98±0.71） mg/g）＞甘蔗地（（0.62±0.74） mg/g）;研究区土壤BSi含量存在随群落变化的季节变化：森林群落土壤BSi含量干季大于湿季，农业草本群落（香蕉和甘蔗）土壤BSi含量则出现湿季大于干季的特征。研究区土壤BSi含量变化主要受生物因素（总氮和碳/氮（C/N））和非生物因素（化学风化程度）耦合驱动。在全球尺度上，海南岛西南部土壤BSi含量（1.43 mg/g）低于热带雨林土壤BSi含量（2.5 mg/g）,揭示水热同期的季风气候区山地土壤较活跃的微生物活动和较强的降雨、径流侵蚀作用，均有利于土壤BSi发生迁移-转换，最终以溶解态硅的形式随地表径流注入南海，在一定程度上保持南海生态系统的营养成分结构，确保南海生态系统良性循环。

作为三峡库区生态调节前置库,汉丰湖水质受流域内农业面源污染和城市生活污染的影响.开展汉丰湖正式运行前后流域水环境演变特征分析研究,明确影响水体营养状态的关键因素,对汉丰湖水环境保护乃至改善三峡库区水环境具有重要的参考意义.本研究综述了2012—2019年汉丰湖水质监测数据相关文献,各指标的质量浓度监测结果表明:溶解氧(DO)、总磷(TP)和高锰酸钾指数(CODMn)年变化较大,总磷(TN)、氨氮(NH+4-N)年浓度差异不显著;TN和NH+4-N随着月份增加整体呈下降趋势,DO、CODMn和叶绿素a(Chla)随着月份增加整体呈先增加后降低趋势,TP随月份增加整体呈先降低后增加的趋势;各监测点位的水体DO、TN、NH+4-N、TP和CODMn质量浓度差异均不显著.汉丰湖水体质量等级为Ⅲ至劣Ⅴ类,呈中营养至轻度富营养状态,TN是主要污染指标.Chla与DO、TN呈显著正相关,与NH+4-N呈正相关,与CODMn和TP呈负相关关系,藻类的生长与溶解氧、氮素含量增加有关.为改善汉丰湖的水体富营养化问题,本文提出了污染源控制、水文调度和生态补偿措施.

生态护岸是土木工程与生态工程相结合的护岸形式,对保护岸坡稳定和河岸生态系统健康起着重要作用.从功能、技术、形式、评价四个方面对生态护岸的研究工作进行梳理,总结出生态护岸具有防洪护堤、净化、生态、景观四个方面的功能,论述了自然原型、半自然型、多自然型三种生态护岸类型的优缺点及适用范围.通过对不同的评价方法进行分析,并从安全性、生态性、景观性、社会经济性等方面建立河道生态护岸综合评价全指标体系,阐述目前生态护岸研究存在的问题,以期为生态护岸技术的发展提供理论基础并明晰研究方向.

山洪灾害是影响重庆市社会稳定和经济发展的主要灾种之一.通过总结2010年以来重庆市山洪灾害防治非工程措施和工程措施项目建设运行管理的现状及成效,全面梳理了当前山洪灾害防治过程中存在的调查评价成果应用不够充分、危险区划分不够精细、预警指标不够精准、平台和站点运行维护不够理想等突出问题和矛盾.在此基础上,坚持目标导向和问题导向,结合山洪灾害防治工作实际,提出了开展山洪灾害调查评价成果拓展应用、增强山洪灾害监测预警能力、强化平台和站点运行维护等针对性的对策和建议,以期为制定下一阶段山洪灾害防治项目的建设目标、任务和举措指明方向.