Inflow and outflow permeability tests in a very soft clay under low stresses

In situ inflow and outflow permeability tests with the BAT probe at SarapuíII soft clay test site are presented.A description of the BAT permeability test is provided,discussing its advantages and shortcomings,especially in the case of very soft clays under low stresses.Pore pressures were monitored during probe installation and were found to be slightly lower than piezocone u2 pore pressures,consistent with the position of the filter.The role of filter tip saturation was investigated after the usual saturation procedure provided an unsatisfactory pore pressure response during probe installation.Results show that the vacuum saturation procedure provides adequate response during installation and increases the reliability of the coefficient of permeability determination in early measurements.Both inflow and outflow tests yielded similar results,indicating that careful execution of the test can lead to good test repeatability regardless of the loading condition.Various sequences of alternated inflow and outflow tests have yielded similar results,indicating that soil reconsolidation and filter clogging were negligible in the tests performed.Data are presented concerning the relationship between index parameters and the in situ coefficient of permeability for SarapuíII clay,which plot outside the range of existing databases.

Characteristics and Effects of Inorganic Nitrogen in East Water-source and Inflow Rivers of Chaohu Lake

[Objective] To study the characteristics and effects of inorganic nitrogen in east water-source and inflow rivers of Chaohu Lake. [Method] The speciation and distribution characteristics of dissolvable inorganic nitrogen （DIN） in east water-source and inflow rivers of Chaohu Lake were investigated, and their effects on water qual- ity were examined. [Result] The concentrations of NH3-N and NO2--N were the high in flood season, and low in non-flood season, while the concentration of NO3--N pre- sented the opposite trend; the concentration of NO3--N was the highest in Shuangqiao estuary, where the pollution was the worst. DIN in Zhegao estuary and Xiaozhegao estuary was mainly caused by domestic sewage and industrial wastewaters; surface runoff and pollution from ships contribute the most to the DIN content in Shuangqiao estuary. [Conclusion] This study provided basic data and theoretical basis for the control and management of eutrophication in Chaohu Lake.

Theory and Practice of Water Pollution Prevention and Control for Inflowing Rivers in Taihu Valley

The pollutants from the 15 rivers inflowing into Lake Taihu accounted for about 80% of the total amount of the pollutants inflowing into Lake Taihu. Therefore, overall treatment of the inflowing rivers of Taihu Lake is of great importance to the improvement of water environment in the valley and the eutrophication status in th lake. Firstly, the basic ideas, key taches and main methods for water pollution control of inflow rivers of Taihu Lake was put forward in this article, Basic on these theories, the pollutant source status in the comprehensive treatment zone of the 15 major inflow rivers was analysized, the countermeasures of pollution control and main regulation projects were introduced, and the total abatement of pollutants was predicted. With the implement of regulation projects, the number of rivers with water quality worse than Grade V among the 15 major inflow rivers had come from 9 to 3, and the eutrophication status of Taihu Lake had changed from medium level to light level. The overall treatment of the major inflow rivers of the Taihu Lake had achieved initial success.

Tailoring the area of hepatic resection using inflow and outflow modulation

The performance of hepatic surgery without a parenchyma-sparing strategy carries significant risks for patient survival because of the not negligible occurrence of postoperative liver failure.The key factor of modern hepatic surgery is the use of the intraoperative ultrasound(IOUS),not only to stage the disease,but more importantly to guide resection with the specific aim to maximize the sparing of the functional parenchyma.Whether in patients with hepatocellular carcinoma and underlying liver cirrhosis,or in patients with colorectal liver metastasis,IOUS allows the performance of the so-called "radical but conservative surgery",which is the pivotal factor to offer a chance of cure to an increasing proportion of patients,who until few years ago were considered only for palliative care.Using some new IOUS-guided surgical maneuvers,which are based on the liver inflow and outflow modulations,more precise anatomically subsegmental-and segmentaloriented resections can be effectively performed.The present work describes the rationale and the surgical technique for a precise tailoring of the area of hepatic resection using the most recent attainments in IOUS.Such important technical achievements should be a fundamental part of the surgical armamentarium of the modern liver surgeon.

An Inexpensive and Simple Experimental Approach for the Estimation of Solute Import into Groundwater and Subsequent Export Using Inflow/Outflow Data

In agricultural catchments where groundwater (GW) base flow discharge contributes substantially towards stream flow, the information linking GW inflow/outflow with contaminant import/export is scarce. However, this information is essential to address aquatic ecosystem health hazard/risk associated with nitrate export and subsequent loading in sensitive surface water bodies (SWB). The objectives of this study were to assess the temporal dynamics of (i) rain water inflow/outflow behaviour in three agricultural catchments in the humid tropics of far-northeast Queensland of Australia, (ii) solute import via inflow and subsequent export in outflow, and (iii) the association between GW inflow/outflow and solute import/export. Approximately 71% of the average seasonal rainfall percolated (inflow) into the porous basaltic regolith of the Johnstone River Catchment (JRC) compared with 44% into the alluvial regolith in the Mulgrave River Catchment (MRC) and 29% into the metamorphic regolith in the Tully River Catchment (TRC), respectively. The outflows from the basaltic, alluvial, and metamorphic regoliths were 56%, 36%, and 55% of the inflows, respectively. The cumulative nitrate import per season was 25 k/ha in the JRC compared with 11 kg/ha in MRC and 34 kg/ha in TRC. The corresponding exports were 24 kg/ha, 8 kg/ha 26 kg/ha in JRC, MRC, and TRC, respectively. The total dissolved solute (TDS) exports were 82%, 77%, 75%, of the corresponding imports in JRC, MRC, and TRC, respectively. Simple correlations indicated that nitrate export was positively correlated with the outflow in each one of the regolith and similar trends were observed between inflow and import. The import/export mass balance for nitrate shows that 73% to 96% of the imports were exported during the same rainy season, suggesting the potential for nitrate associated ecosystem health hazard/risk in sensitive SWB receiving the outflows.

阳澄湖入湖河道分类、污染特征分析及治理策略

为进一步揭示阳澄湖入湖河道的污染物来源,提出相应的治理对策,以2017—2021年阳澄湖入湖河道水质监测数据为基础进行分析讨论。依据入湖水量选取10条主要入湖河道进行分析,其中位于阳澄湖东岸的白曲港在七浦塘拓浚工程建成之前主导流向为出湖,工程建成后,通过Pearson相关分析证实了其流向与七浦塘引水时的水力关系,因此白曲港被选为主要入湖河道。采用距平系数法、系统聚类法和物元分析法将阳澄湖主要入湖河道分为3个类别:第1类别包括白荡、蠡塘河、北河泾、永昌泾4条河道,第2类别包括渭泾塘、界泾和施家斗港3条河道,第3类别包括南消泾、七浦塘和白曲港3条河道。使用因子分析法进行因子分析,第1类别河道的因子为高锰酸盐指数(COD_(Mn))、氨氮(NH_(3)-N)、溶解氧(DO)和总磷(TP),第2类别河道的污染因子为NH_(3)-N、总氮(TN)、pH、TP和DO,第3类别河道的污染因子为pH、TP、TN和DO。通过对上游河道水质情况分析、文件研究以及实地调查等方式得出第1类别河道区域的污染源主要为工业污染源和生活污染源,第2类别河道区域污染源主要为工业污染源与种植业污染源,第3类别河道污染源主要为陆地水产养殖污染源与种植业污染源。针对总体污染源情况,建议通过控制点源污染、削减面源污染、增强上游河道治理、开展生态治理修复以及加强巡查监管等方式对各类别河道区域进行针对性治理,以提高入湖河道水质,为阳澄湖的系统性和整体性治理打好基础。

西南地区典型河道型水库水温结构及水动力机制研究

大型河道型水库在发挥水电效益的同时,其特有的水温分层对水环境的影响不容忽视。现有研究多偏重于水温垂向差异及时空演变规律研究,对于其形成过程的水动力影响研究尚不够深入。本研究利用数学模型模拟分析西南地区典型河道型水库—乌东德水库水温结构变化过程,发现水动力条件是水温结构形成的决定性因素,主温跃层的形成和演变取决于温差异重流导致的水动力机制。2—3月来水下潜于水库底部,二者界面形成主温跃层,并不断向库区下游发展;4—6月来流形成中间流,其上和其下分别形成两个温跃层;7月入库水流为上浮流,其下形成主温跃层;坝前局部区域水体主温跃层因取水孔口动力抽吸作用等温线出现局部收缩。

考虑多源入库水出库水的三门峡-小浪底水库汛期联合优化调控

三门峡-小浪底水库联合运用是黄河调水调沙的关键环节。为更好地发掘三门峡和小浪底水库联合优化调控的潜力,提升水沙调控效果,以汛期来水较多的2020年为例,分析了三门峡和小浪底水库库区降雨、蒸发、支流来水、取用水等入库水和出库水过程,以发电和排沙综合效益为目标函数,建立了考虑多源入库水出库水的三门峡-小浪底水库联合优化调度模型,开展了水沙优化调控研究。研究成果表明:1)库区降雨、蒸发、支流来水及取用水等次要入库水出库水对三门峡水库和小浪底水库水量的贡献分别为2.71亿m^(3)和-0.85亿m^(3)。其中,入库水量主要集中于汛期,而出库水量在全年分布相对均匀。2)三门峡库区的次要入库水出库水量占库容的36%左右,将对三门峡-小浪底水库联合优化调控产生影响。3)考虑多源入库水出库水的三门峡-小浪底水库联合优化调控的排沙量有所增加,小浪底水库的汛期发电效益增加约2599.4万元。

河下浅埋厚煤层采动覆岩裂隙-涌水量时空演化的FDEM-CFD耦合分析

河下浅埋厚煤层采动覆岩裂隙分布与涌水量是工作面安全生产的决定性因素之一。数值模拟是二者重要预测方法,其合理性的关键在于建立岩体破坏-裂隙流体耦合理论及相应的模拟方法。以路家村矿15404工作面为研究背景,构建拉/剪应力下非贯通裂隙开裂、贯通裂隙的法向与切向本构关系,并基于二相流质量守恒、动量守恒与状态方程,结合增强的浸没边界算法识别流-固界面,通过流体体积法实现裂隙内流体自由面的追踪和重构。在此基础上形成FDEM-CFD河下采煤覆岩裂隙与涌水量预测数值模型耦合程序,通过相邻工作面地面钻孔冲洗液消耗量观测法验证导水裂隙带发育高度,以及采用大井法理论对涌水量结果进行对比。结果表明:采动岩体破坏-裂隙流体耦合理论及相应的FDEM-CFD程序,可数值实现河下浅埋厚煤层采动覆岩裂隙形成,以及裂隙内流体运移过程。当工作面推进至80~120 m时覆岩内形成贯通地表的导水裂隙。招山河水的主要下泄路径为工作面后方8~20 m位置处的导水裂隙,其斜向采空区、倾角65°~72°。模拟所得采空区涌水量为18.78 m^(3)/h,与大井法计算结果接近。上述成果在路家村矿区得到初步应用,为进一步开展河下浅埋厚煤层防治水工程提供理论支撑。

SJ油田低产低效油井间开生产模型优化研究

SJ油田属于典型的低渗、特低渗油藏,该油田低产低效井(液量≤3 m^(3)/d,泵效≤30%)占开井数32.1%。低产低效井在连续抽吸过程中,由于地层供液不足,会造成油井处于干抽状态,抽油泵故障率增加等问题。建立了考虑油相渗透率、原油黏度随地层压力变化、同时考虑地层启动压力梯度的油井流入量计算模型。在此基础上,结合井筒的流出动态,建立了低渗透油藏低液量井生产模型。利用Visual Studio语言编写了低产低效油井间开制度优化系统软件,实现了低产低效油井间开工作时间的计算。实例验证表明,油井按照“该模型所确定的间歇开采时间”进行生产,产量均能达到原先连续生产时产量的95%以上,由此节约的电能所产生的经济效益巨大。

巢湖及入湖河流氮素变化特征分析

基于安徽省地表水环境质量监测网监测数据,研究了2013—2022年巢湖主要入湖河流和湖体氮素变化特征。结果表明:10年来,主要入湖河流和湖体总氮年均值范围分别为2.93~6.52 mg/L、1.18~1.72mg/L,氨氮年均值范围分别为0.49~4.98mg/L、0.10~0.44mg/L,入湖河流总氮、氨氮浓度均远高于湖泊。入湖河流和湖体氮素呈现出较为相似的年际变化、季节变化和月度变化特征,总氮、氨氮浓度均冬、春季高,夏、秋季低。巢湖入湖河流新旧污染同时存在。对于Ⅴ类和劣Ⅴ类等污染严重的水体,氨氮占比较高;水质较好的水体,氨氮占比较低。

河道出流提升工程施工技术研究

根据本项目施工任务,开展大型河道清淤和螺旋钢管焊接及浮管施工导流施工工艺的研究。以多区域同时施工、区内多点流水作业的方式组织施工,钢管采用“沉管法”进行施工,利用水浮力通过浮船牵引进行运输,并利用GPS定位系统及水下监测仪器等现代科技手段,采用环保疏浚设备,提高清淤施工速度与精确度、提高生产效率。

鄱阳湖水位对五河来水的时空响应研究

鄱阳湖水位受到长江干流和湖泊流域五河来水(五河分别为赣江、抚河、信江、饶河、修水)的共同影响,其中五河径流为鄱阳湖的主要来流。为探究五河来水变化对鄱阳湖水位的时空影响,结合数据驱动模拟与敏感性分析方法,定量研究了鄱阳湖水位与五河来水的响应关系。首先,结合PSO-GA算法和支持向量回归(SVR)技术建立了湖泊水位预测模型,模拟分析鄱阳湖水位与五河来水的时间响应关系;然后,基于此模型采用连续预测方法研究了鄱阳湖水位对五河来水响应的空间分布特征。结果表明,鄱阳湖水位对五河来水变化响应较强的时期在5~7月,尤以5月响应程度为甚;空间分布上,鄱阳湖湖区中部对五河来水变化的响应程度最高,以2010年5月为例,当五河来流增加40%时,都昌站水位一周内平均可抬高1.16 m,北部星子站、湖口站分别平均抬高1.15、1.03 m,南部棠荫站、康山站平均抬高0.97 m。结果明确了鄱阳湖水位对五河来水的时空响应特征,可为鄱阳湖水资源管理及流域优化调控提供科学依据。

中国劳动力流动减贫效应的时空异质性研究

基于中国30个省份1995-2020年的面板数据,运用机理分析与实证检验相结合的方法,从全国层面、时间层面和地区层面分别考察劳动力流动减贫效应的时空异质性。研究结果发现,劳动力流动通过人力资本集聚、资源配置优化以及消费升级减缓了流入地贫困,劳动力流动通过收入转移和回流效应缓解了流出地贫困。从全国层面看,劳动力流动具有减贫效应;从地区层面看,中部地区的减贫效应优于东部和西部地区;从时间层面看,1995-2009年(第一阶段)和2010-2020年(第二阶段)的劳动力流动都发挥了减贫效应,且2010年以后的减贫效应更明显。本研究既为深入了解劳动力流动减贫效应的时空异质性提供了经验证据,又为巩固拓展脱贫攻坚成果和深度推进乡村振兴提供了决策依据。

太湖西山岛河流秋季沉积物氮、磷特征及其对水质的响应

入湖河流沉积物营养盐的释放制约了河流与太湖水环境的改善。因目前对太湖岛上入湖河流沉积物氮、磷特征及其对水质的响应研究较少,笔者于2020年10月采集西山岛15个代表点位的沉积物样品并测定了其氮、磷含量,进行沉积物对不同初始浓度氨氮(NH_(4)^(+)-N)、磷酸盐(PO_(4)^(3-)-P)的吸附-解吸模拟实验;研究各点位沉积物对水质的响应,确定了需水质管控与沉积物疏浚的点位。结果表明,西山岛河流沉积物总氮、总磷平均含量分别为8.97和2.90 g·kg^(-1);沉积物活性氮、磷平均含量分别为3.77和1.29 g·kg^(-1),存在较高的氮、磷释放风险。根据模拟实验结果,7个点位的沉积物NH_(4)^(+)-N和9个点位的沉积物PO_(4)^(3-)-P处于解吸状态,磷的解吸现象更为严重。通过研究入湖河流沉积物对太湖水环境的影响发现,为维持太湖水环境的稳定,点位CZ1、CZ5在原位水质下仅需进行外源管控,点位CZ4的沉积物需进行疏浚或原位覆盖,其他点位需进行水质改善与沉积物疏浚的综合整治。

跨行政区小流域水污染特征分析

跨行政区的小流域水污染特征复杂,且因行政主体不同而导致水环境治理困难。以合肥市二十埠河小流域为例,采用现场调查和模型计算相结合的方法,开展流域污染特征分析与研究。结果表明,点源为流域内最重要的污染源,由点源产生的各主要污染物入河负荷贡献率达47.3%~65.4%。各行政区域对河流的污染贡献率存在差异,上游的新站区对二十埠河的污染贡献率最高(COD占比47.88%, TP占比45.67%),下游的肥东县内存在大片农田和散户畜禽养殖,造成NH3-N入河负荷较高(37.96%)。新站区(汛期)和肥东县(非汛期)的NH3-N环境容量为负值,为了实现控制目标,分别需要削减NH3-N入河负荷21.60和81.18 t/a。为改善二十埠河水环境质量,建议将点源污染控制作为流域污染治理工作重点,并做好农业面源污染控制,解决NH3-N环境容量不足的问题。

基于控制单元划分的大辽河流域污染物空间分布及来源解析

为明确大辽河流域污染物特征及污染物来源,建立“流域—控制单元—行政区”空间拓扑关系,对2019年大辽河流域国控断面水质情况、各控制单元内污染物入河量及空间分布特征进行分析。结果表明:1)大辽河流域28个水质监测断面中,逐月水质均能达到《水污染防治行动计划》中考核目标的占29%,超标污染物以COD、NH_(3)-N为主,超标断面中,COD、NH_(3)-N主要来源为城镇生活源、农村生活源和分散式畜禽养殖,TP主要来源于不同土地利用类型污染源和城镇生活源;2)2019年COD、NH_(3)-N、TN、TP污染物入河量分别为59195.5、3115.5、18229.7、538.3 t/a,从污染源贡献上看,总体呈现为城镇生活源>农村生活源>分散式畜禽养殖污染源>不同土地利用类型(含林地、草地、耕地、城镇用地)污染源>工业源>规模化畜禽养殖污染源;3)污染物入河量空间分布均呈现中部>西南部>东北部,其中控制单元C3、C6、C8、C11、C13、C15、C17是重点管控单元,以上重点管控单元中,COD、NH_(3)-N、TN、TP污染物入河量贡献率分别为68%、73%、77%、72%;4)污染物入河量估算结果与通量模拟值之间误差均小于20%,可用于研究区范围内污染负荷估算。

白洋淀入淀河流溶解有机物沿程变化特征及来源解析

采用紫外-可见吸收光谱、三维荧光光谱,结合平行因子分析、主成分分析等方法,分析了白洋淀3条入淀河流(府河、孝义河、白沟引河)中发色团溶解有机物(CDOM)的光谱特征,阐释了CDOM组成、来源及对水质的影响机制。结果发现:河流CDOM平均浓度顺序为府河>孝义河>白沟引河,其中,府河CDOM的芳香性与分子量高于其他河流,白沟引河腐殖化程度高于其他河流,孝义河CDOM中内源性物质占比高于其他河流;3条河流均检出类腐殖质组分C1、C2、C3和类蛋白质组分C4,其中C1、C2、C3来源相近,且与C4异源;3条河流各组分最大荧光强度和总荧光强度的沿程变化表明,府河CDOM为点源、面源混合来源,孝义河CDOM以点源输入为主,白沟引河CDOM来自水源本身。

来水不确定对跨流域工程供水调度风险的影响

为量化径流预报的不确定性所产生的供水风险,本文以引汉济渭跨流域调水工程为研究对象,基于来水不确定性的概率分布定义了供水风险,以此建立与求解了供水调度模型,获得了不同预报误差的多尺度供水风险值,厘清了风险升级的预报临界误差,揭示了来水不确定性对跨流域调水工程供水风险的影响。研究表明:产生供水风险的径流预报误差阈值为15%,且预报误差与供水风险呈二次幂函数关系;三河口水库可利用其多年调节水库的性能,缓解预报误差带来的供水风险;将供水风险分为轻险、中险和重险,确定了风险升级的阈值分别为0.117、0.190,对应的预报误差分别为24.0%、32.7%。研究成果将为保障陕西省引汉济渭工程等跨流域调水工程的调水安全提供决策依据。

跨境资本异常波动的风险预警:基于机器学习视角

基于“在险资本流动”的宏观研究新范式,运用预测分位数回归与稳定分布拟合方法,识别出中国的跨境资本异常波动风险。基于包含371个指标的高维数据集,通过构建的Lasso-PCA双重筛选机器学习方法,识别出不同类型跨境资本异动风险的关键预警因子。结果显示:(1)构建的跨境资本异动风险指标能较好地衡量中国所面临的资本流动尾部风险;(2)国内外长期利差扩大是债券资本涌入风险的关键预警因子,美国货币政策收紧是债券资本撤离风险的关键预警因子,全球风险偏好降低是股票资本涌入风险的关键预警因子,而美元名义有效汇率上升是股票资本撤离风险的关键预警因子;(3)2022年以来,美联储持续加息与美元走强会增加中国的跨境资本撤离风险。在金融市场双向开放进程加快的背景下,为中国防范化解外部冲击风险提供了重要参考依据。