AN APPLICATION OF THE ANALYTIC ELEMENT METHOD IN MODELING FLORIDA EVERGLADES HYDROLOGY1

ABSTRACT: The large volumes of ground water that are discharged from the Everglades toward the Miami metropolitan area have historically posed a significant environmental water supply problem. In order to analyze the effects of seepage barriers on these subsurface outflows, the analytic element modeling code GFLOW was used to construct a ground water flow model of a region that includes a portion of the Everglades along with adjacent developed areas. The hydrology of this region can be characterized by a highly transmissive surficial aquifer in hydraulic contact with wetlands and canals. Calibration of the model to both wet and dry season conditions yielded satisfactory results, and it was concluded that the analytic element method is a suitable technique for modeling ground water flow in the Everglades environment. Finally, the model was used to evaluate the potential effectiveness of a subsurface barrier approximately two miles long for increasing water levels within the adjacent fringes of the Everglades National Park. It was found that the barrier had a negligible effect on water levels due to both its relatively short length and the high transmissivity of the surficial aquifer.     

EFFECTS OF WOODY VEGETATION ON SANDY LEVEE INTEGRITY1

he influence of woody vegetation on the reliability of a sandy levee was investigated using field data in seepage and slope stability analyses. Field data were collected from selected sites within a 10-km segment of a channel levee on the Sacramento River near Elkhorn, California. Root architecture and distribution were determined using the profile-wall method in which root cross sections were exposed in the vertical wall of an excavated trench. Transects running both parallel and perpendicular to the crest of the levee were excavated at six sites. Each site was dominated by different plant species: five sites were adjacent to trees or woody shrubs, while one supported only herbaceous growth. Lateral plant roots were primarily restricted to, and modified, the near-surface soil horizons to a depth of approximately 1 meter. Root area ratios (RARs) did not exceed 2.02 percent and generally decreased exponentially with depth. At depths greater than 20 cm, mean RARs for sites dominated by wood species were not significantly different from the mean RAB for the herbaceous site. No open voids clearly attributable to plant roots were observed. Roots reinforced the levee soil and increased shear resistance in a measurable manner. Infinite slope and circular arc stability analyses were performed on the landward and riverward slopes under different hydraulic loading conditions. Infinite slope analyses indicated increasing root area ratio from 0.01 percent to 1 percent increased the factor of safety from less than one to more than seven. Circular arc analyses indicated that even the lower measured root concentrations sufficed to increase safety factors for arcs with maximum depths of about 1 m from less than one to about 1.2. Our findings suggest that allowing woody shrubs and small trees on levees would provide environmental benefits and would enhance structural integrity without the hazards associated with large trees such as wind-throwing.     

EVALUATION OF INFLOW TO MIRROR LAKE,NEW HAMPSHIRE1

ABSTRACT: Measured stream discharge plus calculated ground water discharge (total measured runoff) were compared with runoff calculated by the unit-runoff method for the two largest watersheds of Mirror Lake for 1981–1983. Runoff calculated by the unit-runoff method, using Hubbard Brook watershed 3 as the index watershed, was greater than the total measured runoff into Mirror Lake during periods of high flow and slightly less than the total measured runoff into Mirror Lake during periods of low flow. Annual calculated unit runoff was 17 to 37 percent greater than total measured runoff. Differences in monthly runoff are far greater, ranging from 0 to greater than 100 percent. For high flows the calculated unit runoff is about 2 times greater than total measured runoff. For low flows the northwest basin of Mirror Lake has the greatest ground water contribution compared to the other two basins. In contrast, Hubbard Brook watershed 3 has the least ground water contribution.     

地热水在矿山深部岩体单一裂隙中的渗流规律分析

选取PKN模型进行岩体裂隙地热水对流换热量的研究,计算了地热水在裂隙内的对流换热量,通过将裂隙截面展开求解对流换热面积,根据牛顿冷却定律计算得出对流换热量;由裂隙张开度的变化量计算岩体裂隙的渗流量,结果表明,在三维应力一定的条件下,岩体裂隙内地热水的渗流量随裂隙倾角变化而变化。从矿山中选取典型岩样进行加工,使之成为200 mm×100 mm×200 mm的标准岩样。试验结果表明,在裂隙倾角α=0°的情况下,裂缝的渗流量随β增加逐渐减小,并且在随β增加到90°的过程中趋于稳定,表明岩体裂缝为水平裂缝时渗流量最小,维持在一个稳定值;在α=90°的情况下,裂缝的渗流量随β增加逐渐增大,在β增加到90°的过程中,裂缝慢慢变为垂直裂缝,渗流量的变化也趋于缓和,增加到一个稳定值。     

基于CFD的注采管柱接头修复胶液渗流规律研究*

为探讨注胶方法修复井下注采管柱螺纹接头缝隙的可行性,采用计算流体动力学欧拉-欧拉多相流方法构建胶液在注采管柱接头缝隙内的渗流流动数值仿真模型,模拟注胶压力驱动下修复胶液在管柱接头螺纹缝隙内的渗流过程,通过多工况条件下胶液在螺纹缝隙内的渗流数值模拟,研究注胶压力、胶液密度和螺纹失效缝隙对胶液渗流过程的影响。结果表明:基于欧拉-欧拉多相流的数值模型可有效预测胶液在管柱接头缝隙内的流动;胶液在狭缝内的渗流深度与注胶压力呈正比;胶液渗流深度与胶液密度呈反比;胶液渗流深度与螺纹缝隙尺寸呈正比。     

分层填料土地毛管渗滤系统处理生活污水的研究

研究了煤渣与土壤分层装填的土地毛管渗滤系统处理生活污水的效果;该系统未种植物前的运行初期,进水溶解氧浓度的增加可促进好氧微生物的生长繁殖,使其较快处于稳定期;在系统运行稳定后,在装置表面种植了植物,进水溶解氧浓度的减少对系统去除污染物效果的影响不明显;在出水达到国家二级排放标准的情况下,该系统所能承受的最高水力负荷为0.2m/d,与常规的纯土壤地下渗滤系统运行水力负荷仅能<0.05m/d相比,提高了单位面积处理污水的能力,节省了占地面积。     

垃圾填埋场渗滤液回灌调蓄池的容量设计方法

根据垃圾填埋场渗滤液回灌处理的特点 ,提出了调蓄水池容量的计算方法。对渗滤液调蓄水池设计中应注意的问题进行了讨论     

一种新型防渗材料的研究

我国城市生活垃圾最主要的处理方法是生态填埋。而最关键的是其防渗层的研究。讨论了用HAS土壤固化剂固化粉砂土，结果表明开发出的防渗材料拥有良好的性能。低廉的价格，并能消纳一定量的工业废渣。可用于各种固体废物堆放场及作为路基材料等。     

索风营水电站库区左岸河间地块喀斯特渗漏勘察技术

喀斯特渗漏勘察是喀斯特地区水利水电工程建设项目勘测设计的重要内容,成果评价将对工程产生重大影响甚至制约到工程成立与否。本文拟以索风营水电站水库左岸河间地块的喀斯特水文地质勘察为实例,对有关勘察工作的技术路线、勘察技术、喀斯特水库渗漏评价方法及处理思路作相应的探讨。     

垃圾填埋场渗滤液及产生量的控制措施

城市生活垃圾卫生填埋是当今世界上使用最广的垃圾处理方式.从垃圾的收集,垃圾分拣,以及良好的填埋场设计及施工是保证其正常运转的先决条件.国外填埋技术的运用和研究起步较早,在各方面理论和实践已经相当成熟.中国进行垃圾填埋处置应在立足本国国情和实际情况的基础上,积极学习和引进国外成果,建立起自己的一整套规范,设计出经济、合理的垃圾回收、处理系统,以达到经济、社会、环境效益的统一.在分析了垃圾填埋场渗滤波的来源、渗滤液中污染物的特点及其变化规律,渗滤液量的计算,以及控制垃圾填埋场渗滤液的方法以后.围绕垃圾填埋场的污染特点提出了一些建议.