油田区地下水系统特殊防污性能评价

针对中国典型油田区的水文地质条件、主要石油类污染物性质,对地下水防污性能评价模型DRASTIC进行了改进,建立了油田区地下水系统特殊防污性能评价模型——DORKI。在该模型中选取DRASTIC模型中的地下水埋深、净补给量、包气带介质3个评价因子,增加了土壤有机质含量和有机碳-水分配系数Koc2个评价因子。根据相关资料确定了新增评价因子的评分并通过层次分析法中的九标度法确定了5个评价因子的权重。最后结合某油田区的情况,对DORKI进行实例应用和分析,结果表明,DORKI模型能够较为准确地用于原油组分对油田区地下水的污染风险评价。     

地下水脆弱性和风险性评价研究进展综述

地下水脆弱性和风险性评价与区划是区域地下水资源保护的重要依据。本文回顾了各国地下水脆弱性评价与编图研究工作以及地下水污染风险评价研究的最新进展,提出地下水污染风险评价的框架及其指标体系,最后指出今后需要深入研究的问题。     

Current trends and future challenges in groundwater vulnerability assessment using overlay and index methods

 The concept of groundwater vulnerability is a useful tool for environmental planning and decision-making. Many different methods have been developed for assessing this vulnerability. Hydrogeologists have failed to reach a consensus concerning the definitions of and reference terms for groundwater vulnerability assessment. Therefore, a review of vulnerability assessment and mapping methods providing a new classification system is necessary. This is focused on techniques that use the overlay and index class methods. New research challenges in vulnerability assessment are identified, especially the need for developing dynamic links between numerical models and overlay and index methods. Received: 28 October 1998 · Accepted: 31 May 1999     

Nitrogen isotope indicators of seasonal source variability to groundwater

 A nitrogen isotope study of soil water and groundwater in southern Indiana, USA, in 1991–1992 demonstrated considerable variations in nitrate degradation processes compared to an earlier investigation in 1986–1987. Although N-fertilizers were applied in May 1991, the δ¹⁵N values in soil water decreased in February 1992, indicating its delayed release into the system after substantial rainfall. The δ¹⁵N values of groundwater decreased from +12.3‰ in November 1991 to +11.3‰ in February 1992, and to +7.5‰ in March 1992. The increased residence time of nitrate in the soil resulted in increased denitrification, ammonia volatilization and plant uptake, and reduced threat to the groundwater quality. The 1986–1987 study in the area reported that excessive rainfall during the summer rapidly transported the nitrate to deeper horizons and drastically reduced volatilization and microbial reduction of nitrate, thus increasing the immediate threat to the groundwater quality in the area. The present study demonstrated that nitrogen isotopic signatures can be used to determine the effects of local soil type, rainfall, and land-use practices on the fate of nitrate in the subsurface. Received: 18 February 1997 · Accepted: 17 June 1997     

Regional characterisation of hydraulic properties of rock using air-lift data

 Hydrogeologic studies are commonly data-intense. In particular, estimations of hydraulic properties of hard rock often require large amounts of data. In many countries, large quantities of hydrogeologic data have been collected and archived over the years. Therefore, the use of existing data may provide a cost-efficient alternative to collecting new data in early stages of hydrogeologic studies, although the available data may be considered imprecise. Initially, however, the potential usefulness, i.e., the expected accuracy, of the available data in each specific case must be carefully examined. This study investigates the possibilities of obtaining estimates of transmissivity from hard-rock air-lift data in Sweden within an order of magnitude of results obtained from high-quality injection-test data. The expected accuracy of the results was examined analytically and by means of statistical methods. The results were also evaluated by comparison with injection-test data. The results indicate that air-lift data produce estimates of transmissivity within an order of magnitude compared to injection-test data in the studied examples. The study also shows that partial penetration and hydrofracturing may only affect the estimations approximately half an order of magnitude. Thus, existing data may provide a cost-efficient alternative to collection of new data in early stages of hydrogeologic studies. Received, January 1998 Revised, November 1998, December 1998 Accepted, December 1998     

基于AHP的DRASTIC模型对莱州地区地下水脆弱性研究

地下水脆弱性评价是作为地质环境评价的一部分,目前国内外已有众多研究,并提出多种评价模型,其中以DRASTIC方法模型使用最为广泛。AHP（层次分析法）是一种层次权重决策分析方法,综合专家经验与理论数据,可以实现定性与定量二者有效的统一结合,更真实客观的反映研究区评价结果。文中以莱州地区为研究区,在全面调查区内的地质条件、水文地质条件、地形地貌、气象等实际情况的基础上,利用AHP法对目前使用的DRASTIC方法模型进行改进。对原模型中的7个参数进行权重重新取值,然后建立一套符合研究区的地下水脆弱性模型,并进行评价分区,最终绘制了地下水脆弱性分区图。     

Geomorphic aspects of groundwater flow

 The many roles that groundwater plays in landscape evolution are becoming more widely appreciated. In this overview, three major categories of groundwater processes and resulting landforms are considered: (1) Dissolution creates various karst geometries, mainly in carbonate rocks, in response to conditions of recharge, geologic setting, lithology, and groundwater circulation. Denudation and cave formation rates can be estimated from kinetic and hydraulic parameters. (2) Groundwater weathering generates regoliths of residual alteration products at weathering fronts, and subsequent exhumation exposes corestones, flared slopes, balanced rocks, domed inselbergs, and etchplains of regional importance. Groundwater relocation of dissolved salts creates duricrusts of various compositions, which become landforms. (3) Soil and rock erosion by groundwater processes include piping, seepage erosion, and sapping, important agents in slope retreat and headward gully migration. Thresholds and limits are important in many chemical and mechanical groundwater actions. A quantitative, morphometric approach to groundwater landforms and processes is exemplified by selected studies in carbonate and clastic terrains of ancient and recent origins. Received, May 1998 · Revised, September 1998 · Accepted, October 1998     

Estimation of groundwater recharge using the chloride mass-balance method, Pingtung Plain, Taiwan

 Due to rapid economic growth in the Pingtung Plain of Taiwan, the use of groundwater resources has changed dramatically. Over-pumping of the groundwater reservoir, which lowers hydraulic heads in the aquifers, is not only affecting the coastal area negatively but has serious consequences for agriculture throughout the plain. In order to determine the safe yield of the aquifer underlying the plain, a reliable estimate of groundwater recharge is desirable. In the present study, for the first time, the chloride mass-balance method is adopted to estimate groundwater recharge in the plain. Four sites in the central part were chosen to facilitate the estimations using the ion-chromatograph and Thiessen polygon-weighting methods. Based on the measured and calculated results, in all sites, including the mountain and river boundaries, recharge to the groundwater is probably 15% of the annual rainfall, excluding recharge from additional irrigation water. This information can improve the accuracy of future groundwater-simulation and management models in the plain. Received, April 1996 Revised, March 1997, November 1997 Accepted, March 1998     

Assessing rapid environmental change using geoindicators

 Geoindicators are high-resolution measures of short-term (<100 years) surface or near-surface changes in earth processes, and phenomena that are significant for environmental monitoring and assessment. They are based on standard concepts and procedures and can be used to track changes in fluvial, coastal, desert, mountain, permafrost and other terrestrial areas. Geoindicators assess both catastrophic events and those that are more gradual, but evident within a human lifespan. Most deal with changes on the landscape (0.1–10 km) and meso-scales (10–100 km), but some, such as relative sea level and volcanic unrest, have regional and global dimensions. Some are complex and costly to measure, others are relatively simple and easy to apply. Geoindicators can also be used to unravel trends over the past few centuries and longer through paleoenvironmental research, thus providing the important baselines against which human-induced and natural stresses can be better understood. Geoindicators have been designed by the International Union of Geological Sciences as an aid to state-of-the-environment reporting and long-term ecological monitoring. Received: 26 July 1996 / Accepted: 1 November 1996     

The influence of Zihe Stream on the groundwater resources of the Dawu well field and on the discharge at the Heiwang iron mine, Zibo City area, Shandong Province, China

 The Dawu well field, one of the largest in China, supplies most of the water for the Zibo City urban area in Shandong Province. The field yields 522,400–535,400 m³/d from an aquifer in fractured karstic Middle Ordovician carbonate rocks. Much of the recharge to the aquifer is leakage of surface water from Zihe Stream, the major drainage in the area. Installation of the Taihe Reservoir in 1972 severely reduced the downstream flow in Zihe Stream, resulting in a marked reduction in the water table in the Dawu field. Since 1994, following the installation of a recharge station on Zihe Stream upstream from the well field that injects water from the Taihe Reservoir into the stream, the groundwater resources of the field have recovered. An average of 61.2×10³ m³/d of groundwater, mostly from the Ordovician aquifer, is pumped from the Heiwang iron mine, an open pit in the bed of Zihe Stream below the Taihe Reservoir. A stepwise regression equation, used to evaluate the role of discharge from the reservoir into the stream, confirms that reservoir water is one of the major sources of groundwater in the mine. Received, May 1998 / Revised, May 1999 / Accepted, June 1999     

Patterns in groundwater chemistry resulting from groundwater flow

 Groundwater flow influences hydrochemical patterns because flow reduces mixing by diffusion, carries the chemical imprints of biological and anthropogenic changes in the recharge area, and leaches the aquifer system. Global patterns are mainly dictated by differences in the flux of meteoric water passing through the subsoil. Within individual hydrosomes (water bodies with a specific origin), the following prograde evolution lines (facies sequence) normally develop in the direction of groundwater flow: from strong to no fluctuations in water quality, from polluted to unpolluted, from acidic to basic, from oxic to anoxic–methanogenic, from no to significant base exchange, and from fresh to brackish. This is demonstrated for fresh coastal-dune groundwater in the Netherlands. In this hydrosome, the leaching of calcium carbonate as much as 15 m and of adsorbed marine cations (Na⁺, K⁺, and Mg²⁺) as much as 2500 m in the flow direction is shown to correspond with about 5000 yr of flushing since the beach barrier with dunes developed. Recharge focus areas in the dunes are evidenced by groundwater displaying a lower prograde quality evolution than the surrounding dune groundwater. Artificially recharged Rhine River water in the dunes provides distinct hydrochemical patterns, which display groundwater flow, mixing, and groundwater ages. Received, May 1998 · Revised, August 1998 · Accepted, October 1998     

改进的DRASTIC模型在地下水易污染性模糊评价中的应用

为了有效避免地下水系统遭受污染,保护地下水资源,采用改进的DRASTIC模型对地下水易污染性进行了评价.鉴于DRASTIC模型的诸多缺陷,将模糊综合评价方法运用到模型中,构建了各评价指标于各个级别的最优相对隶属度矩阵;引用语气算子确定指标权重,计算出了研究区样本集的级别特征值向量.将样本的易污染性进行排序,用研究区样段的水质评价结果进行了验证,结果证明,易污染性程度越高的地区综合评价水质越差;为进一步验证评价方法的真实性,将易污染性排序结果与传统DRASTIC法评价排序结果进行对比,两种方法排序一致.可见,本次改进的模型在克服了DRASTIC的诸多缺陷的同时,使得计算结果真实、可靠,且更加体现了计算过程的科学性与合理性.     

Groundwater vulnerability assessment of the SW Trans-Danubian Central Range, Hungary

 The most important karst water reservoir of Hungary is found in the SW Trans-Danubian Central Range, selected as test area for the proposed "system approach" and the application of GIS/ARC-INFO to vulnerability mapping. In addition, a case-study exemplifies the particularities of regional karst-aquifer vulnerability, and moreover the interpretation of data and maps from the very same point of view. The work has resulted in plotting an atlas to be a useful tool in the hands of land-users and waste-disposal managers, helping them to prevent groundwater deterioration. Received: 22 July 1996 · Accepted: 12 September 1997     

Contributions of groundwater conditions to soil and water salinization

 Salinization is the process whereby the concentration of dissolved salts in water and soil is increased due to natural or human-induced processes. Water is lost through one or any combination of four main mechanisms: evaporation, evapotranspiration, hydrolysis, and leakage between aquifers. Salinity increases from catchment divides to the valley floors and in the direction of groundwater flow. Salinization is explained by two main chemical models developed by the authors: weathering and deposition. These models are in agreement with the weathering and depositional geological processes that have formed soils and overburden in the catchments. Five soil-change processes in arid and semi-arid climates are associated with waterlogging and water. In all represented cases, groundwater is the main geological agent for transmitting, accumulating, and discharging salt. At a small catchment scale in South and Western Australia, water is lost through evapotranspiration and hydrolysis. Saline groundwater flows along the beds of the streams and is accumulated in paleochannels, which act as a salt repository, and finally discharges in lakes, where most of the saline groundwater is concentrated. In the hummocky terrains of the Northern Great Plains Region, Canada and USA, the localized recharge and discharge scenarios cause salinization to occur mainly in depressions, in conjunction with the formation of saline soils and seepages. On a regional scale within closed basins, this process can create playas or saline lakes. In the continental aquifers of the rift basins of Sudan, salinity increases along the groundwater flow path and forms a saline zone at the distal end. The saline zone in each rift forms a closed ridge, which coincides with the closed trough of the groundwater-level map. The saline body or bodies were formed by evaporation coupled with alkaline-earth carbonate precipitation and dissolution of capillary salts. Received, May 1998 · Revised, July 1998 · Accepted, September 1998     

Scale aspects of groundwater flow and transport systems

Flow-system analysis is based on the concept of hierarchical groundwater flow systems. The topography of the water table, which is strongly related to the topography of the land surface, is a major factor in the hierarchical nesting of gravity-driven groundwater flow, resulting in flow systems of different orders of magnitude in lateral extent and depth of penetration. The concept of flow systems is extremely useful in the analysis of spatial and temporal scales and their mutual relationships. Basic equations on the laboratory scale are extended to larger, regional scales. Making use of Fourier analysis further develops Tóth's original idea of topography-driven flow systems. In this way, the different spatial scales of the water table are separated in a natural way, leading to a simple expression for the penetration depth of a flow system. This decomposition leads also to the relationship between spatial and temporal scales. Analogous to flow systems, water bodies with different water quality may be called 'transport systems.' Field studies, numerical micro-scale modeling over macro-scale domains, and stochastic dispersion theory indicate that between systems with steady transport, the interfaces are relatively thin. The interfaces are much thinner than the relatively large mixing zones predicted by the conventional engineering approach to macrodispersion, in which relatively large, time-independent macrodispersion lengths are applied. A relatively simple alternative engineering approach is presented. For macrodispersion of propagating solute plumes, the alternative dispersion term gives the same results as the conventional engineering approach and gives correct results for steady-state transport.     

Plan for a groundwater monitoring network in Taiwan

 In Taiwan, rapid economic growth, rising standards of living, and an altered societal structure have in recent years put severe demands on water supplies. Because of its stable quantity and quality, groundwater has long been a reliable source of water for domestic, agricultural, and industrial users, but the establishment of a management program that integrates groundwater and surface-water use has been hampered by the lack of groundwater data. In 1992, the Department of Water Resources (DWR) initiated a program entitled "Groundwater Monitoring Network Plan in Taiwan." Under this program, basic groundwater data, including water-level and water-quality data, are being collected, and a reliable database is being established for the purpose of managing total water resources. This paper introduces the goals, implementation stages, and scope of that plan. The plan calls for constructing 517 hydrogeologic survey stations and 990 groundwater monitoring wells within 17 years. Under this program, water-level fluctuations are continuously monitored, whereas water-quality samples are taken for analysis only at the initial drilling stage and, subsequently, at the time when a monitoring well is being serviced. In 1996, the DWR and the Water Resources Planning Commission were merged to form today's Water Resources Bureau. Received, July 1997 · Revised, February 1998 · Accepted, January 1998     

Relation of streams, lakes, and wetlands to groundwater flow systems

 Surface-water bodies are integral parts of groundwater flow systems. Groundwater interacts with surface water in nearly all landscapes, ranging from small streams, lakes, and wetlands in headwater areas to major river valleys and seacoasts. Although it generally is assumed that topographically high areas are groundwater recharge areas and topographically low areas are groundwater discharge areas, this is true primarily for regional flow systems. The superposition of local flow systems associated with surface-water bodies on this regional framework results in complex interactions between groundwater and surface water in all landscapes, regardless of regional topographic position. Hydrologic processes associated with the surface-water bodies themselves, such as seasonally high surface-water levels and evaporation and transpiration of groundwater from around the perimeter of surface-water bodies, are a major cause of the complex and seasonally dynamic groundwater flow fields associated with surface water. These processes have been documented at research sites in glacial, dune, coastal, mantled karst, and riverine terrains. Received, April 1998 · Revised, July 1998, August 1998 · Accepted, September 1998     

Sustainable groundwater resources, Heretaunga Plains, Hawke's Bay, New Zealand

 The Heretaunga Plains, Hawke's Bay, New Zealand, is underlain by Quaternary fluvial, estuarine-lagoonal, and marine deposits infilling a subsiding syncline. Within the depositional sequence, river-channel gravels form one of the most important aquifer systems in New Zealand. An interconnected unconfined–confined aquifer system contains groundwater recharged from the Ngaruroro River bed at the inland margin of the plain, 20 km from the coast. At the coast, gravel aquifers extend to a depth of 250 m. In 1994–95, 66 Mm³ of high quality groundwater was abstracted for city and rural water supply, agriculture, industry, and horticulture. Use of groundwater, particularly for irrigation, has increased in the last 5 years. Concern as to the sustainability of the groundwater resource led to a research programme (1991–96). This paper presents the results and recommends specific monitoring and research work to refine the groundwater balance, and define and maintain the sustainable yield of the aquifer system. Three critical management factors are identified. These are (1) to ensure maintenance of consistent, unimpeded groundwater recharge from the Ngaruroro River; (2) to specifically monitor groundwater levels and quality at the margins of the aquifer system, where transmissivity is <5000 m²/d and summer groundwater levels indicate that abstraction exceeds recharge; (3) to review groundwater-quality programs to ensure that areas where contamination vulnerability is identified as being highest are covered by regular monitoring. Received, January 1998 / Revised, August 1998, March 1999 / Accepted, April 1999