Tropical Cyclogenesis in the Intra-Americas Sea: Hurricane Cindy (2005)     

Jinwoong Yoo  Jennifer M. Collins  Robert V. Rohli 《The Professional geographer》2013,65(3):511-524

The tropical cyclogenesis (TCG) of Atlantic Hurricane Cindy (2005) was investigated to study environmental conditions preceding mesoscale vortex development in the Intra-Americas Sea (IAS; i.e., the Gulf of Mexico and Caribbean Sea) using the ERA-Interim Reanalysis pressure level data. Major findings include that the development of a mesoscale vortex occurred downward over Central America due to 600 hPa level enhanced winds downstream of southeasterly winds from northern South America, triggering Cindy's TCG in a few days. The contribution of midlevel enhanced winds should be noted as a potential precursor of other TCGs in the IAS.  相似文献   

The impact of well drawdowns on the mixing process of river water and groundwater and water quality in a riverside well field,Northeast China     

Yaguang Zhu  Yuanzheng Zhai  Qingqing Du  Yanguo Teng  Jinsheng Wang  Guang Yang 《水文研究》2019,33(6):945-961

Riverbank filtration (RBF) has been widely used throughout the world as an effective means to regulate surface water and groundwater resources and pretreat raw water for municipal water supply. The quality of the water from a riverside well field and the mixing ratios of surface water and groundwater is primarily impacted by the hydrodynamic processes in the RBF system. The RBF system is largely controlled by the water exploiting system in addition to the natural hydrologic condition of the river–aquifer system. As one of the most important design parameters of the riverside well field, the drawdown of groundwater level greatly determines the water head differences between the river water and groundwater as well as the field flow net, which subsequently impacts the mixing of river water and groundwater and water quality significantly. This study aimed to improve the understanding of the mixing process between the surface water and groundwater and estimate the impact of the RBF on the mixing ratio of surface water–groundwater and water quality quantitatively. A set of field pumping tests with various groundwater level drawdowns were carried out independently and successively at a riverside field with a single pumping well near the Songhua River in Northeast China in August 2017. During these tests, the water levels and hydrochemical parameters of the Songhua River, the adjacent aquifer, and the pumping well were monitored. The dynamic mixing process of the river water and groundwater and water quality under various drawdown conditions were analysed systematically using analytical methods. The results obtained from Dupuit method and the Mirror Image method in conjunction with the Hydrochemical Tracing method showed that the pumping water directly from the river water reached 60% ± 10% after a steady flow net was established. The larger the proportion of the pumping water captured from the river, the better quality of the pumping water was, because the quality of the river water (only limited to some water quality parameters monitored which were minority) was better than that of the groundwater. The results also showed that total Fe, TDS, total hardness, COD_Mn, and K⁺ were relatively sensitive to the changes of groundwater drawdown, and their concentrations decreased with an increase in the groundwater drawdown. It can be concluded that both the mixing ratio of the surface water and the groundwater and the water quality of the riverside well field can be regulated through adjusting the designed drawdown of the groundwater level, which is helpful for the design and the optimization of the riverside well water intake engineering.  相似文献   

反硝化增强去除乙醇对多孔介质渗透性的影响   总被引：1，自引：0，他引：1  

蒋亚萍  陈余道  张燕  黄月群 《高校地质学报》2010,16(1):32-38

随着乙醇混合汽油的不断推广应用,乙醇将成为地下水中与苯、甲苯、乙苯及二甲苯的同分异构体（BTEX）共存的一种新型污染物。通过4 个含水砂柱实验,研究了乙醇存在及其强化去除对含水介质渗透性能的影响。结果表明：在有限溶解氧与反硝化增强修复条件下,乙醇去除率达92% 以上;生物过程对介质渗透能力影响程度随乙醇初始浓度、消耗速率与补充频率而变化：乙醇初始浓度接近1 000 mg/L 和3 000 mg/L 时,乙醇消耗快,补充频率高,渗透系数下降总体上有连续性,最大下降幅度达一个数量级（×10-1 cm/s）;乙醇初始浓度达到5 000 mg/L 时,渗透性下降显著,可下降两个数量级,但乙酸的积累可影响生物活性,并使得渗透性变化出现反复;当不含乙醇时,汽油溶解组分对介质渗透性能的影响相对不明显。  相似文献   

Diurnal-period,wind-forced ocean variability on the inner shelf off Concepción,Chile     

Marcus Sobarzo  Luis Bravo  Carlos Moffat 《Continental Shelf Research》2010

We characterize the response of diurnal-period ocean current variability to the sea breeze using measurements of current velocity taken off the mouth of the Itata River and wind stress collected at Hualpen Point (central Chile) in spring of 2007 and summer of 2006 and 2008. During these three periods, the winds are predominately towards the northeast, following the coastal topography, with the highest variability found in the near-diurnal and synoptic frequency bands. The sea breeze amplitude is intermittent in time and is associated with synoptic-scale variability on the order of three to 15 days, so that the diurnal-period winds (and currents) are enhanced when the alongshore wind (i.e. upwelling-favorable) is strong. The water current variability in the near-diurnal band is significant, explaining up to 40% (spring 2007) of the total current variance in the first 15 m depth.  相似文献   

Hydraulic modeling of riverbank filtration systems with curved boundaries using analytic elements and series solutions     

Mark Bakker 《Advances in water resources》2010

A new analytic solution approach is presented for the modeling of steady flow to pumping wells near rivers in strip aquifers; all boundaries of the river and strip aquifer may be curved. The river penetrates the aquifer only partially and has a leaky stream bed. The water level in the river may vary spatially. Flow in the aquifer below the river is semi-confined while flow in the aquifer adjacent to the river is confined or unconfined and may be subject to areal recharge. Analytic solutions are obtained through superposition of analytic elements and Fourier series. Boundary conditions are specified at collocation points along the boundaries. The number of collocation points is larger than the number of coefficients in the Fourier series and a solution is obtained in the least squares sense. The solution is analytic while boundary conditions are met approximately. Very accurate solutions are obtained when enough terms are used in the series. Several examples are presented for domains with straight and curved boundaries, including a well pumping near a meandering river with a varying water level. The area of the river bottom where water infiltrates into the aquifer is delineated and the fraction of river water in the well water is computed for several cases.  相似文献   

煤层应力敏感性及其对压裂液滤失的影响   总被引：2，自引：0，他引：2  

冯利娟  郭大立  曾晓慧  朱卫平  刘川庆 《煤田地质与勘探》2010,38(2):14-17

压裂液滤失系数是压裂设计中非常重要的参数。由于煤层中的渗透率、孔隙度等物性对应力极为敏感,在对煤层进行压裂设计时,若直接用试井和测井测得的渗透率和孔隙度值代入滤失系数的计算公式,算出的结果可能与实际情况严重不符。通过实验室内不断改变围压的方式来模拟煤储层上覆压力的变化情况,建立了某盆地煤层应力与渗透率之间的关系,并在考虑煤层物性应力敏感性的情况下,探讨了煤层压裂液综合滤失系数的计算方法。结果发现,压裂液综合滤失系数及岩心渗透率与净围压的关系均符合指数递减规律。另外,通过对动态渗透率的拟合,使得到的综合滤失系数远远大于未考虑应力情况下的综合滤失系数,这样能更准确地反映实际情况。   相似文献   

Designing Metallic Iron Packed‐Beds for Water Treatment: A Critical Review          下载免费PDF全文

Chicgoua Noubactep 《洁净——土壤、空气、水》2016,44(4):411-421

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Integrating the science education nexus into coastal governance: A Mediterranean and Black Sea case study     

Christopher House  Michael R. Phillips 《Marine Policy》2012,36(2):495-501

Although continued knowledge acquisition is necessary, there is an increasing need for innovative manipulation. Consequently, the roles of sound science and considered educational practice need clarification within coastal policy. Research data, collected via semi-structured interviews with representatives of government and quasi government organisations encompassing various Mediterranean and Black Sea countries, was subsequently assessed alongside published work. Principal findings emphasised that policy makers need to engage more coherently with the existing science education nexus to facilitate, but not format research agendas. Although extensive information is readily available, there is need for further manipulation, translation, coordination, communication and adaptation between policy portfolios. Consequently, the science education nexus should be internalised into policy formulation, implementation and monitoring. Furthermore, to develop shared awareness, considered dissemination of knowledge and understanding requires both vertical and horizontal integration. Policy results should be clear and innovative knowledge transfer fora, using Technology Enhanced Dissemination (TED) within culturally sensitive contexts, must be developed. Science and education require legal incorporation from which professional norms and authority can evolve. Findings suggested that although the science is ‘hard’, incorporating it into policy decisions is ‘harder’ and hence, more effort is needed.  相似文献   

Recovery of Polyvinyl Alcohol from Desizing Wastewater Using a Novel High‐Shear Ultrafiltration Module     

Ankur Sarkar  Debasish Sarkar  Madhurima Gupta  Chiranjib Bhattacharjee 《洁净——土壤、空气、水》2012,40(8):830-837

Polyvinyl alcohol (PVA), the major constituent of desizing water constituting 45% of the total BOD load has a significant environmental impact owing to its poor biodegradability. In order to prevent PVA from being discharged by the effluent stream, modern textile industries opt for membrane based separation techniques using ultrafiltration so that the recovery and recycle of PVA in tandem could be achieved. However, the process of ultrafiltration is still not widely accepted as expected due to the well‐known non‐idealities of concentration polarization and pore blockage. In this article, design and performance characterization of a lab‐scale novel shear enhanced ultrafiltration unit, named as spinning basket membrane (SBM) module are discussed. The proposed module is unique in terms of its inbuilt cleaning facility eliminating the effects of polarization and subsequent periodic fouling leading to its uninterrupted production operation. The test fluid, necessarily a solution of PVA was treated in the proposed module under different parametric conditions with polyvinylidene fluoride (PVDF) membranes of two different molecular weight cut‐off (50 and 100 kDa). After 2 h of continuous operation the permeate flux was observed to be within 95–97% of the respective initial fluxes. Such performance is rarely been attained in practice. Hence, the novelty of the present research is achieved. Considering the performance of the present module in terms of flux regeneration and product recovery, it may be regarded as an efficient device and can be potentially deployed for cleaning of other industrial wastewater.  相似文献   

Heat Flow and Geothermal Potential in the South-Central United States     

Petru T. Negraru  David D. Blackwell  Kamil Erkan 《Natural Resources Research》2008,17(4):227-243

Geothermal exploration is typically limited to high-grade hydrothermal reservoirs that are usually found in the western United States, yet large areas with subsurface temperatures above 150°C at economic drilling depths can be found east of the Rocky Mountains. The object of this paper is to present new heat flow data and to evaluate the geothermal potential of Texas and adjacent areas. The new data show that, west of the Ouachita Thrust Belt, the heat flow values are lower than east of the fault zone. Basement heat flow values for the Palo Duro and Fort Worth Basins are below 50 mW/m² while, in the frontal zone of the belt, they can exceed 60 mW/m². Further east, along the Balcones fault system the heat flow is in general higher than 55 mW/m². The eastern most heat flow sites are in Louisiana and they show very high heat flow (over 80 mW/m²), which is associated with the apparently highly radioactive basement of the Sabine uplift. The geothermal resource in this area is large and diverse, and can be divided in high grade (temperature above 150°C) convective systems, conductive based enhanced geothermal systems and geothermal/geopressured systems. One of the most attractive areas east of the cordillera extends from eastern Texas across Louisiana and Arkansas to western Mississippi. Here temperatures reach exploitation range at depths below 4 km, and tapping such a resource from shut in hydrocarbon fields is relatively easy. The initial costs of the development can be greatly reduced if existing hydrocarbon infrastructure is used, and therefore using shut-in hydrocarbon fields for geothermal purposes should not be neglected.  相似文献