Coastal aquifer response to extreme storm events in Emilia‐Romagna,Italy          下载免费PDF全文

Beatrice M.S. Giambastiani  Nicolò Colombani  Nicolas Greggio  Marco Antonellini  Micòl Mastrocicco 《水文研究》2017,31(8):1613-1621

With global warming and sea level rise, many coastal systems will experience increased levels of inundation and storm flooding, especially along sandy lowland coastal areas, such as the Northern Adriatic coast (Italy). Understanding how extreme events may directly affect groundwater hydrology in shallow unconfined coastal aquifers is important to assess coastal vulnerability and quantify freshwater resources. This study investigates shallow coastal aquifer response to storm events. The transitory and permanent effects of storm waves are evaluated through the real time monitoring of groundwater and soil parameters, in order to characterize both the saturated and unsaturated portions of the coastal aquifer of Ravenna and Ferrara (southern Po Delta, Italy). Results highlight a general increase in hydraulic head and soil moisture, along with a decrease in groundwater salinity and pore water salinity due to rainfall infiltration during the 2 days storm event. The only exceptions are represented by the observation wells in proximity to the coastline (within 100 m), which recorded a temporary increase in soil and water salinity caused by the exceptional high waves, which persist on top of the dune crest during the storm event. This generates a saline plume that infiltrates through the vadose zone down to the saturated portion of the aquifer causing a temporary disappearance of the freshwater lens generally present, although limited in size, below the coastal dunes. Despite the high hydraulic conductivity, the aquifer system does not quickly recover the pre‐storm equilibrium and the storm effects are evident in groundwater and soil parameters after 10 days past the storm overwash recess.  相似文献   

Modelling of colloidal particle and heavy metal transfer behaviours during seawater intrusion and refreshing processes          下载免费PDF全文

Bo Tan  Shuguang Liu  Chaomeng Dai  Hui Zhou  Zhenquan Hui  Guihui Zhong  Hong Zhang 《水文研究》2017,31(22):3920-3931

The proper management of coastal aquifers commonly requires an understanding of regional mass flow and complete seawater–freshwater circulation. In this study, time series observations of seawater intrusion and refreshing were conducted using a column experiment based on natural flow conditions in coastal groundwater and a sampled medium from a coastal sandy aquifer without chemical treatment. Ranges of hydrodynamic and hydrochemical variables were tested and analysed. The results showed that the zeta potential of suspended colloids in aqueous solution in an aquifer polluted with 0.5 g/kg of heavy metals exhibited an isoelectric point for pH values ranging from 5.70 to 6.07 when freshwater or seawater completely occupied the aquifer pores, which is representative of natural hydrochemical conditions. In this scenario, a high background concentration of heavy metals induced colloidal immobilization. Otherwise, seawater–freshwater circulation enabled colloid mobilization due to ionic strength and pH fluctuations. The migration of multiple heavy metals occurred at a characteristic time of approximately 1 pore volume after each intrusion stage began and when the peak rate of colloid release was reached. At these times, the colloid behaviour determined the quantity and pathway of heavy metal transport. On the basis of the influences of seawater and freshwater interactions, the quantity of mobilized particles generally decreased and was uniformly distributed in each fraction due to particle loss and decreased porous connectivity. We speculate that the decrease in the total surface area of the migratory colloids may cause colloid‐associated heavy metal transport to decrease. The experimental results provide a useful basis for testing coastal groundwater flow and mass transport models because these phenomena require full characterization to precisely evaluate the associated fluxes from the field scale to the microscopic dimension.  相似文献   

黑潮入侵优化对南海北部中尺度涡旋模拟的影响   总被引：1，自引：1，他引：0  

封宝鑫  刘海龙  林鹏飞 《海洋学报(英文版)》2020,39(3):12-24

基于高分辨率海洋环流模式，通过比较吕宋海峡处地形优化后的黑潮入侵形态和强度不同的试验，我们研究了黑潮入侵优化后对南海中尺度涡模拟的影响。我们发现黑潮入侵的减弱导致了涡旋活动的减弱，这使得模式结果与观测结果更为相近。在这种情况下，模式模拟的吕宋海峡西部及北部陆坡区域的涡动动能明显减弱。模式涡动动能的减弱与模式反气旋式涡数量的减少和气旋式涡强度的减弱有关。涡动动能收支的分析进一步表明，黑潮入侵的优化将通过改变水平速度切变和温跃层斜率来改变涡动动能，而这两个参数分别与正压和斜压不稳定性有关。前者在模式涡动动能减弱中起着更为重要的作用，而黑潮入侵导致的涡动动能的水平输送对吕宋海峡西部区域的能量收支同样起着重要的作用。  相似文献   

热带风暴Bilis(2006)登陆期间一波非对称降水分布成因的探讨   总被引：2，自引：0，他引：2  

石顺吉  余锦华  张大林 《热带海洋学报》2009,28(1)

利用中尺度数值模式WRF-ARW对Bilis(2006)进行数值模拟,并进行地形和下垫面因素2个敏感性试验,诊断分析Bilis(2006) 登陆期间一波非对称降水结构形成的动力因子.综合分析3个试验,结果表明环境垂直风切变对Bilis(2006) 一波非对称降水结构形成的影响显著大于地形、登陆过程下垫面属性的改变和风暴移动速度的影响,冷空气的侵入对降水形成也有重要贡献.垂直切变的作用使顺切变左侧形成强降水,冷空气的作用与垂直切变的作用相互配合可能是顺切变方向和顺切变方向右侧强降水的主要成因.  相似文献   

Modelling Salt Intrusion and Nitrate Concentrations in the Ythan Estuary     

P.A. Gillibrand  P.W. Balls 《Estuarine, Coastal and Shelf Science》1998,47(6):695-706

A one-dimensional salt intrusion model is used to investigate the hydrography of the Ythan estuary, a small shallow macrotidal estuary in the north-east of Scotland. The model simulates the longitudinal distributions of water level, salinity and total oxidized nitrogen (TON) in the estuary. The model employs upstream differencing and the Smolarkiewicz anti-diffusion scheme to avoid the numerical difficulties typically encountered when modelling strong tidal flows using centred differences. The physical mechanisms driving the simulations are the tide at the entrance to the estuary and freshwater discharge at the head. The model was calibrated against measurements of water level made at three locations in the estuary, salinity observations made at a central platform and axial salinity distributions. At both spring and neap tides, the full range of salinity observed at the central platform was simulated. However, at the midway stage between springs and neaps, the simulated peak salinity was less than that observed. This was probably due to the sensitivity of the model to the digitisation of the estuarine bathymetry.The model successfully simulated salinity distributions for periods of high and low river flow, and was used to illustrate how TON concentrations fluctuated in response to variations in river flow. The potential implications of variations in the bathymetry of the estuary on salinity and nutrient distributions were predicted to be slight. However, the four fold increase in riverine TON concentrations that has occurred over the past 30 years was shown to increase TON distributions along the entire length of the estuary. The calculated estuary flushing time was strongly dependent on river flow and varied between 11–60 h.  相似文献   

Salt-wedge propagation in a Mediterranean micro-tidal river mouth     

Kiriaki Haralambidou  Georgios SylaiosVassilios A. Tsihrintzis 《Estuarine, Coastal and Shelf Science》2010

The dynamics of a seasonally formed salt-wedge propagating along the micro-tidal channel of Strymon River estuary, Northern Greece, and its consequences on river water quality, are thoroughly studied through intensive sampling campaigns. The wedge is developed at the downstream river part, under the summer limited freshwater discharge conditions (Q < 30 m³/s). The geometric features of the wedge (length and thickness) appeared directly related to Strymon River discharge. A maximum intrusion length of 4.7 km along Strymon River estuary was observed under minimum river discharge of almost 6 m³/s. Relations produced from in situ data illustrate that limited river flow expands the wedge horizontally, reducing its vertical dimension, while higher flows lead to increased wedge thickness. Estuarine flushing time ranges between 0.2 and 1.5 days, exponentially dependent on Strymon River discharge. Wedge velocities depicted tidal asymmetry between tidal phases, with consistent inward motion, even under the ebb tidal stage. Strong vertical stratification prevails throughout the tidal cycle, proving the limited vertical mixing between the two layers, although higher interfacial stresses are produced in ebb. Bottom topography plays an interesting role in wedge propagation, as the presence of an underwater sill either prevents saline intrusion during flood or isolates the front of the wedge from its core at the ebb. Ecological consequences of salt-wedge propagation in Strymon River estuary are the frequent evidence of bottom hypoxic conditions and the increased TSS levels, leading to the occurrence of a turbidity maximum at the tip of the salt-wedge. Higher BOD and ammonium levels were mostly observed at the river end, associated to point and non-point pollution sources. Nitrates and silicates were found associated with freshwater fluxes, while ammonia levels were related to saline intrusions. The reduced phosphorus freshwater fluxes, resulting from phosphorus uptake at the upstream reservoir (Kerkini Lake) and the increased bottom turbidity induced by the salt-wedge seem responsible for the limited chlorophyll-a levels along Strymon River estuary.  相似文献   

Groundwater modelling and marine intrusion in the semi‐arid systems (Cap‐Bon,Tunisia)     

Adel Zghibi  Lahcen Zouhri  Jamila Tarhouni 《水文研究》2011,25(11):1822-1836

This article studies the effect of drought and pumping discharge on groundwater supplies and marine intrusion in the Korba aquifer (Cap‐Bon peninsula, Tunisia). The Groundwater Modelling System has been used to model the groundwater flow and to simulate the seawater intrusion. The calibration is based on the groundwater levels in the steady state from 1963, and in the transient state from the groundwater levels from 1963 to 2005. The main objective is to quantify the components of the groundwater mass balance and to estimate the hydraulic conductivity distribution. The impact of pumping discharge on the groundwater level evolution has been examined by two pumping scenarios P1 (no. 8420) and P2 (no. 8862) wells. The hydrodynamic modelling shows the increasing drawdowns after 14 years of pumping: 4 m in P1 well and about 5 m in P2 well below sea level. The drawdowns are accompanied by the inverse hydraulic gradient. The numerical model was used to discuss the management of the groundwater resources of Cap‐Bon. As the population continues to grow and the demand for groundwater pumping intensifies beyond the 1963 level, it can be expected that the actual extent of seawater intrusion in the future would be more severe than the model prediction. Better strategies for groundwater development and management will be necessary to protect the freshwater aquifers to the marine intrusion. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

莱州湾沿岸平原海水入侵灾害的发展进程   总被引：10，自引：0，他引：10  

庄振业  刘冬雁  杨鸣  李洪江  邱汉学  宁丕海  宋维华  徐至进 《中国海洋大学学报(自然科学版)》1999,(1)

莱州湾东、南沿岸平原的海（咸）水入侵是人为过量采取地下水和自然环境变化共同引发的灾害。根据多年观测数据绘制的地下水位负值区、淡水资源超采量和海（咸）水入侵面积等三标志划分灾害进程为初始阶段、发展阶段、恶化阶段和缓解阶段。给出了灾害发展模式。以此解释新区灾害,针对灾害发展的不同阶段,采取适时而有效的防灾减灾对策和措施。  相似文献   

渤海莱州湾南岸平原浅埋古河道带及其与海(咸)水入侵关系研究   总被引：2，自引：0，他引：2  

李道高  韩美  赵明华  姜爱霞 《海洋学报》1999,21(6):64-71

根据2100余个钻孔资料,并结合大比例尺地形图、航片、卫片判读分析,以及野外实地考察和沉积物样品的粒度分析、岩相分析、14C测年,研究了莱州湾南岸平原浅埋古河道带的分布规律、埋藏和沉积特征、古河道的分期断代以及与海(咸)水入侵关系。该区在埋深60m内的浅埋古河道带,可分成弥河、潍河和白浪河3个系统,它们大都呈掌状、放射状分布,并与其所属河流的冲洪积扇范围相吻合。该区古河道的形成和发育与古气候和海平面变化密切相关。自晚更新世晚期以来,该区有4期古河道发育,其中玉木旱冰期古河道和玉术主冰期古河道的砂层沉积粒度粗、连通性好、分布广,既是富水性强、水质好的淡水含水层,又是该区海(咸)水入侵的主要通道。控制在浅埋古河道带超采地下淡水,并在丰水季节利用其进行地下水回灌,是治理该区海(咸)水入侵灾害的重要措施之一。  相似文献   

Sectional distribution of salinity and its indication of Kuroshio''s intrusion in the southern Taiwan Strait and northeastern South China Sea late summer, 1994     

Hu Jianyu  Liang Hongxing  Zhang Xuebin 《海洋学报(英文版)》1999,(2):225-236

INTRODUCTIONIn the late summer Of 1994 (from the end of August to the beginning of September), R/VsOcean Research l, Yanping 2, Ocean Research 3 and XiangWnghong 14 conducted a quasi-simultaneous comprehensive investigation in the southern Taiwan Strait (STS), the northeasternSouth China Sea (SCS) and their adjacent areas, and got CTD data from more than 330 stations.Based on sectional salinity distribution of 10 selected sections, this paper analyses the sectionaldistribution of…  相似文献