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1.
Water level is decreased during foundation pit excavation to avoid water inrush under confined water pressure. Cut-off wall is often used as waterproof curtain to partially cut off the dewatered aquifer. When a foundation pit is located in a built-up area and the underlying confined aquifer is not cut off, the drawdown must be minimized outside the pit to avoid land subsidence in buildings and pipelines. The coupling effect of the cut-off wall and pumping well is used to control the drawdown outside the foundation pit. However, the coupling mechanism is not intuitively well understood because of the limitations of existing experimental methods. In this study, transparent soil was introduced to model the coupling mechanism in the physical model test. High-purity fused silica and mixed paraffin oil were used as skeleton and fluid to simulate the confined aquifer and groundwater. Industrial solid dye and paraffin oil were used as tracers. A camera was used to collect flow information. Tests were performed for the combinations of cut-off wall and partially penetrating pumping wells. The insertion depth ratio of the cut-off wall most effectively influenced the drawdown. The layout of the pumping wells in horizontal direction influenced water level distribution and flow rate. The optimal depth of the pumping wells was 1–5 m above the bottom of the cut-off wall, and the optimal horizontal distance between the cut-off wall and the pumping wells was 25% of the pit width. Non-Darcy flow was observed within the range of 0–10 m around the bottom of the cut-off wall. These results were significant in understanding the cut-off wall and pumping well coupling effect on foundation pit dewatering. 相似文献
2.
Land subsidence from deep well pumping has been affecting Bangkok for the past 35 years. Its impact is particularly critical because of the flat low-lying topography and the presence of a thick soft clay layer at the ground surface that augment flood risk and foundation engineering problems, respectively. The subsidence reached its most critical state in the early 1980s when it occurred at a rate as high as 120 mm/year. The rate decreased in the subsequent period but the subsidence-affected area expanded following the growth of the city. Despite various attempts implemented to remedy the crisis, groundwater pumping from the thick aquifer system underneath the city continued to increase from 1.2 million m 3/day in the early 1980s to more than 2.0 million m 3/day at the turn of the century. Piezometric levels in the main aquifer layers had been drawn down by as much as 65 m. Monitoring data showed a clear correlation between the subsidence and piezometric drawdown. The data suggested that for 1 m 3 of groundwater pumped out in Bangkok Plain, approximately 0.10 m 3 of ground loss occurred at the surface. Significant development has been made in numerical methods for prediction of differential settlements between building foundations caused by the piezometric drawdown in the aquifers. The strict mitigation measures adopted recently, comprising a pricing policy for groundwater management, an expansion of tap water supply, and strict enforcement of groundwater laws, have resulted in a marked drop in groundwater use. However, the land subsidence will continue for a long while owing to the time-dependent consolidation behavior of the soft clay layer and clay aquitards. 相似文献
3.
The present study assesses groundwater resources in the semiarid central Sudan, where 20 deep productive wells were installed
to supply a major city in the region, El Obeid. The wells, which has an average 20 L/s discharge each, are taping a deep semiconfined
to confined aquifer of fluvial silisiclastics deposited in the Tertiary–Pleistocene. Groundwater modeling was used as a technique
to interpret the hydrologic system in arid to semiarid central Sudan and to simulate the future influence of the project on
the hydrogeologic system. The simulation confirmed that steady-state flow conditions have been currently reached as indicated
by consistency of computed heads. It also calibrated the values of the conductivity and recharge and ensured the sustainability
of the El Obeid water supply project. A total of 3.5 × 10 7 m 3/year can be continually extracted from the deep aquifer to supply El Obeid city without endangering the groundwater resources
in the region. The decline in water level will not exceed 25 m during the first 10 years, while indefinite continuous pumping
will affect only the vicinity of the wells in a circle of 30 km diameter. Therefore, aquifer storage capacity and hydraulic
properties encourage further groundwater exploitation. The present use of groundwater is extremely lower than the present
demand, and it can potentially cover future demands without introducing significant changes to the system. The increase of
pumping cost due to the decline in head subsequent to project operation was found to be minimal and of local effect. 相似文献
4.
Subway traffic is now being developed in China on a large scale and the planning subway stations are often located in dense
district with tall building. The dewatering of confined aquifer may cause ground settlement, the cracking, deformation and
tilting of the building, and even collapse. Combing with the dewatering project of environment protection of the pit of Yishan
Road station of Shanghai subway No. 9, through the inversion of seepage parameters based on the field pumping test, the hydraulic
barrier function of the underground continuous wall is simulated. The result indicates that with the reduction of the exposed
length of the filter tube and the increase of that enclosed, the drawdown of the confined aquifer decreases. Especially with
the increase of the enclosed length of the filter tube, the drawdown outside the pit can be controlled effectively. According
to the result of the numerical simulation, the design of the continuous concrete wall of the pit for Shanghai Subway No. 9
is altered and the depth of the continuous concrete wall of the standing part and that in the end well are increased to 61
and 62 m, respectively. The monitored result of the equal drawdown pumping test indicates that the drawdown outside the pit
with a distance of 1–6 m to the wall is less than 2 m; It means that there is nearly no influence on the environment around
the pit during dewatering. 相似文献
5.
Groundwater plays an important role in the economic development and ecological balance of the arid area of northwest China.
Unfortunately, human activity, for example groundwater extraction for irrigation, have resulted in excessive falls in groundwater
level, and aquifer overdraft in the oasis, disrupting the natural equilibrium of these systems. A groundwater numerical model
for Minqin oasis, an arid area of northwest China, was developed using FEFLOW software to simulate regional groundwater changes
under transient conditions. The vertical recharge and discharge (source/sink terms) of the groundwater models were determined
from land-use data and irrigation systems for the different crops in the different sub-areas. The calibrated model was used
to predict the change for the period from 2000 to 2020 under various water resources management scenarios. Simulated results
showed that under current water resources management conditions groundwater levels at Minqin oasis are in a continuous drawdown
trend and groundwater depth will be more than 30 m by 2020. Reducing the irrigation area is more effective than water-saving
irrigation to reduce groundwater decline at Minqin oasis and the annual groundwater budget would be −0.978 × 10 8 m 3. In addition, water-diversion projects can also reduce the drawdown trend of groundwater at Minqin oasis, and the groundwater
budget in the Huqu sub-area would be in zero equilibrium if the annual inflow into the oasis was enhanced to 2.51 × 10 8 m 3. Furthermore, integrative water resources management including water-diversion projects, water-saving irrigation, and reducing
the irrigation area are the most effective measures for solving groundwater problems at Minqin oasis. 相似文献
6.
Jordan is an arid country with very limited water resources. Groundwater is the main source for its water supply. Mujib aquifer
is located in the central part of Jordan and is a major source of drinking water for Amman, Madaba and Karak cities. High
abstraction rates from Mujib aquifer during the previous years lead to a major decline in water levels and deterioration in
groundwater quality. Therefore, proper groundwater management of Mujib aquifer is necessary; and groundwater flow modeling
is essential for proper management. For this purpose, Modflow was used to build a groundwater flow model to simulate the behavior
of the flow system under different stresses. The model was calibrated for steady state condition by matching observed and
simulated initial head counter lines. Drawdown data for the period 1985–1995 were used to calibrate the transient model by
matching simulated drawdown with the observed one. Then, the transient model was validated by using drawdown data for the
period 1996–2002. The results of the calibrated model showed that the horizontal hydraulic conductivity of the B2/A7 aquifer
ranges between 0.001 and 40m/d. Calibrated specific yield ranges from 0.0001 to 0.15. The water balance for the steady state
condition of Mujib aquifer indicated that the total annual direct recharge is 20.4 × 10 6m 3, the total annual inflow is 13.0 × 10 6 m 3, springs discharge is 15.3 × 10 6 m 3, and total annual outflow is 18.7 × 10 6 m 3. Different scenarios were considered to predict aquifer system response under different conditions. The results of the sensitivity
analysis show that the model is highly sensitive to horizontal hydraulic conductivity and anisotropy and with lower level
to the recharge rates. Also the model is sensitive to specific yield 相似文献
7.
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 Mm 3 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 m 2/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 相似文献
8.
Zakynthos, an island of 408 km 2 in the Ionian Sea, is completely dependent on its groundwater resources for fulfilling the demands of the water supplies.
The use of groundwater resources has become particularly intensive during the last decades because of the intense urbanization,
the tourist development and the irrigated land expansion that took place. The main aquifers are developed in limestones (karstic),
sandstones of neogene deposits (confined) and alluvial deposits (phreatic). This paper focuses on the assessment of their
hydrogeological characteristics and the groundwater quality. For this investigation, groundwater level measurements, drilling
data, pumping tests and chemical analyses of groundwater samples were used. The average annual consumption that is abstracted
from the aquifer systems, is 4.9 × 10 6 m 3 year −1. The exploitable groundwater reserves were estimated to be 3.3 × 10 6 m 3 year −1. In the last decades, the total abstractions exceed the natural recharge, due to the tourist development; therefore the aquifer
systems are not used safely. The results of chemical analyses showed a deterioration of the groundwater quality. According
to the analyses the shallow alluvial aquifer and the confined aquifer are polluted by nitrates at concentrations in excess
of 25 mg L −1. High sulphate concentrations might be related to the dissolution of gypsum. Seawater intrusion phenomena are recorded in
coastal parts of aquifer systems. The increased Cl − concentrations in karstic aquifer indicate signs of overexploitation. Strengths, weaknesses, opportunities and threats (SWOT)
analysis was applied in order to evaluate the SWOT of the groundwater resources. Moreover, some recommendations are made to
assist the rational management that aim at improving the sustainability of the groundwater resources of Zakynthos Island. 相似文献
9.
指出承压含水层盖层的弯曲变形与开采井周围的径向地下水运动存在相互作用, 而这一效应在传统的井流理论中没有被认识到.通过引入弹性薄板理论, 建立了无越流的承压含水层井流-顶板弯曲效应的解析模型, 同时考虑了含水层和水的压缩性, 结果表明Theis井流方程给出的抽水降深偏小.在此基础上推导了有越流承压含水层井流-盖层弯曲效应的偏微分方程, 求出了解析解, 并与传统理论的结果进行了对比, 表明Hantush-Jacob公式计算的降深也是偏小的.在抽水井附近和抽水初期, 传统理论可能导致显著的相对误差. 相似文献
10.
由于地下水突涌风险,地下空间在施工作业中有必要通过抽水试验确定承压含水层的水文地质参数。依据勘察报告的初步评价,基坑开挖15.5m时,场地内第⑦1层承压含水层有可能产生突涌,为确保工程安全施工,需开挖前进行承压含水层抽水试验,取得场地承压含水层水文地质参数及降水引起的沉降特征,为地下空间设计和施工提供可靠依据。本次布设抽水井、观测井、分层沉降标组、孔隙水压力观测孔及地面沉降观测点,依据抽水试验技术要求获取渗透系数、抽水影响半径等相关水文地质参数。最后,针对工程场地内承压水情况及特点进行分析,提出基坑开挖时的承压水降压建议方案。 相似文献
11.
The Alburni massif (1742m a.s.l.) stretches NW–SE, about 23km long and 9–10km wide, covering 246km 2 with an average elevation of about 940m a.s.l. This massif, with more than 500 caves, is the most important karst area in southern Italy. The karst channel network is hierarchically organized: some channels feed a major spring (1m 3/s) with a very short transit time while others communicate directly with the basal water table related to other springs ( Q > 3m 3/s).There are several dolines and swallow holes just above the basal water table and in the urbanized areas; for years a swallow hole directly transferred pollutants into the aquifer. The contamination vulnerability map shows that the prevalent vulnerability degree ranges from high to very high, due to the widespread karstification of the area and to the presence, on the plateau, of large vegetated areas with gentle slopes favouring fast infiltration.Hence it is important to ascertain the human impact on the area and the consequent contamination risk of the aquifer of the Alburni karst area. Three main layers were created to assess groundwater contamination risk: the vulnerability map, the hazard map, and the value map.The groundwater contamination risk map stresses the importance in a park area of aquifer vulnerability, which strongly influences the risk: indeed, the prevalent moderate degree of risk in the final map depends on the high vulnerability and the low hazard degree. However, in the future it is crucial to take into account the nature of the agricultural land use allowed in the park, which could increase the hazard degree and consequently the risk degree. 相似文献
12.
Earth fissures in Jiangsu Province, China have caused serious damages to properties, farmlands, and infrastructures and adversely
affected the local or regional economic development. Under the geological and environmental background in Jiangsu Province,
this paper presents the earth fissures caused by excessive groundwater withdrawal and coupled by distinctive geological structures
such as Ancient Yellow River Fault in Xuzhou karst area, and Ancient Yangtze River Course and bedrock hills in Suzhou, Wuxi,
and Changzhou area. Although all the earth fissures are triggered by groundwater exploitation, the characteristics are strongly
affected by the specific geological and hydrogeological settings. In particular, in the water-thirsty Xuzhou city, the cone
of depression caused by groundwater extraction enlarged nearly 20 times and the piezometric head of groundwater declined 17 m
over a decade. As groundwater is extracted from the shallowly buried karst strata in the Ancient Yellow River Fault zone,
the development of earth fissures is highly associated with the development of karstic cavities and sinkholes and their distribution
is controlled by the Ancient Yellow River Fault with all the 17 sinkholes on the fault. On the other hand, in the rapidly
developing Southern Jiangsu Province, groundwater is mainly pumped from the second confined aquifer in the Quaternary, which
is distributed neither homogeneously nor isotropically. The second confined aquifer comprises more than 50 m thick sand over
the Ancient Yangtze River Course, but this layer may completely miss on the riverbank and bedrock hills. With a typical drawdown
rate of 4–6 m per annum, the piezometric head of groundwater in the second confined aquifer has declined 76 m at Maocunyuan
since 1970s and 40 m at Changjing since mid-1980s, and a large land subsidence, e.g., 1,100 mm at Maocunyuan, is triggered.
Coupled with the dramatic change of the bedrock topography that was revealed through traditional geological drilling and modern
seismic reflection methods, the geological-structure-controlled differential settlement and earth fissures are phenomenal
in this area. 相似文献
13.
This paper uses Visual MODFLOW to simulate potential impacts of anthropogenic pumping and recharge variability on an alluvial
aquifer in semi-arid northwestern Oklahoma. Groundwater withdrawal from the aquifer is projected to increase by more than
50% (relative to 1990) by the year 2050. In contrast, climate projections indicate declining regional precipitation over the
next several decades, creating a potential problem of demand and supply. The following scenarios were simulated: (1) projected
groundwater withdrawal, (2) a severe drought, (3) a prolonged wet period, and (4) a human adjustment scenario, which assumes
future improvements in water conservation measures. Results indicate that the combined impacts of anthropogenic pumping and
droughts would create drawdown of greater than 12 m in the aquifer. Spatially, however, areas of severe drawdown will be localized
around large-capacity well clusters. The worst impacts of both pumping and droughts will be on stream–aquifer interaction.
For example, the projected aquifer pumpage would lead to a total streamflow loss of 40%, creating losing stream system regionally.
Similarly, a severe drought would lead to a total streamflow loss of >80%. A post-audit of the model was also carried out
to evaluate model performance. By simulating various stress scenarios on the alluvial aquifer, this study provides important
information for evaluating management options for alluvial aquifers. 相似文献
14.
Evaluation of major ion chemistry and solute acquisition process controlling water chemical composition were studied by collecting
a total of fifty-one groundwater samples in shallow (<25 m) and deep aquifer (>25 m) in the Varanasi area. Hydrochemical facies,
Mg-HCO 3 dominated in the largest part of shallow groundwater followed by Na-HCO 3 and Ca-HCO 3 whereas Ca-HCO 3 is dominated in deep groundwater followed by Mg-HCO 3 and Na-HCO 3. High As concentration (>50 μg/l) is found in some of the villages situated in northeastern parts (i.e. adjacent to the concave
part of the meandering Ganga river) of the Varanasi area. Arsenic contamination is confined mostly in tube wells (hand pump)
within the Holocene newer alluvium deposits, whereas older alluvial aquifers are having arsenic free groundwater. Geochemical
modeling using WATEQ4F enabled prediction of saturation state of minerals and indicated dissolution and precipitation reactions
occurring in groundwater. Majority of shallow and deep groundwater samples of the study area are oversaturated with carbonate
bearing minerals and under-saturated with respect to sulfur and amorphous silica bearing minerals. Sluggish hydraulic conductivity
in shallow aquifer results in higher mineralization of groundwater than in deep aquifer. But the major processes in deep aquifer
are leakage of shallow aquifer followed by dominant ion-exchange and weathering of silicate minerals. 相似文献
15.
A buried channel has been located, in the basaltic terrain, near village Shenoli, District Satara, Maharashtra. It is composed of a gritty mass formed of a semi-consolidated material. The resistivity value of the semi-consolidated formation is 6.30 Ohm — m whereas the resistivity values of the vesicular basalts range between 18 and 32 Ohm-m. The specific capacity, unit area specific capacity, specific capacity index, transmissivity and hydraulic conductivity, with respect of the buried channel, are 609.07 LPM/m of drawdown, 12.12 LPM/m 3, 95.47 LPM/m 2, 353.26 m 2/day and 55.37 m/day, respectively whereas the values of these parameters for basalt aquifers range from 67 to 117 LPM/m of drawdown, 0.7 to 4.27 LPM/m 3, 14.08 to 31.04 LPM/m 2, 33.5 to 73.71 m 2/day and 9.44 to 18.32 m/day, respectively. A comparison of the well characteristics and aquifer parameters reveal that the buried channel with semi-consolidated formation has distinctly better groundwater yielding properties. 相似文献
16.
The study area Hindon -Yamuna interfluve region is underlain by a thick pile of unconsolidated Quaternary alluvial deposits and host multiple aquifer system. Excessive pumping in the last few decades, mainly for irrigation, has resulted in a significant depletion of the aquifer. Therefore, proper groundwater management of Hindon-Yamuna interfluve region is necessary. For effective groundwater management of a basin it is essential that careful zone budget study should be carried out. Keeping this in view, groundwater flow modelling was attempted to simulate the behavior of flow system and evaluate zone budget. Visual MODFLOW, pro 4.1 is used in this study to simulate groundwater flow. The model simulates groundwater flow over an area of about 1345 km 2 with a uniform grid size of 1000 m by 1000 m and contains three layers, 58 rows and 37 columns. The horizontal flows, seepage losses from unlined canals, recharge from rainfall and irrigation return flows were applied using different boundary packages available in Visual MODFLOW, pro 4.1. The river — aquifer interaction was simulated using the river boundary package. Simulated pumping rates of 500 m 3/day, 1000 m 3/day and 1500 m 3/day were used in the pumping well package.The zone budget for the steady state condition of study area indicated that the total annual direct recharge is 416.10 MCM and the total annual groundwater draft through pumping is of the order of 416.63 MCM. Two scenarios were considered to predict aquifer system response under different conditions. Sensitivity analysis on model parameters was conducted to quantitatively evaluate the impact of varying model inputs. Based on the results obtained from the sensitivity analysis, it was found that the model is more sensitive to hydraulic conductivity and recharge parameter. Present study deals with importance of groundwater modelling for planning, design, implementation and management of groundwater resources. 相似文献
17.
Overextraction of groundwater is widely occurring along the coast where good quality groundwater is at risk, due to urbanization, tourist development and intensive agriculture. The Sabratah area at the northern central part of Jifarah Plain, Northwest Libya, is a typical area where the contamination of the aquifer in the form of saltwater intrusion, gypsum/anhydrite dissolution and high nitrate concentrations is very developed. Fifty groundwater samples were collected from the study area and analysed for certain parameters that indicate salinization and pollution of the aquifer. The results demonstrate high values of the parameters electrical conductivity, sodium, potassium, magnesium, chloride and sulphate which can be attributed to seawater intrusion. The intensive extraction of groundwater from the aquifer reduces freshwater outflow to the sea, creates drawdown cones and lowering of the water table to as much as 30 m below mean sea level. Irrigation with nitrogen fertilizers and domestic sewage and movement of contaminants in areas of high hydraulic gradients within the drawdown cones probably are responsible for the high nitrate concentration towards the south of the region. Seawater intrusion and deep salt water upconing result in general high SO 4 2? concentrations in groundwater near the shoreline, where localized SO 4 2? anomalies are also due to the dissolution of sebkha deposits for few wells in the nearby sebkhas. Upstream, the increase in SO 4 2? concentrations in the south is ascribed to the dissolution of gypsum at depth in the upper aquifer. 相似文献
18.
Groundwater systems in the San Luis Valley, Colorado, USA have been re-evaluated by an analysis of solute and isotopic data. Existing stream, spring, and groundwater samples have been augmented with 154 solute and isotopic samples. Based on geochemical stratification, three groundwater regimes have been identified within 1,200 m of the surface: unconfined, upper active confined, and lower active confined with maximum TDS concentrations of 35,000, 3,500 and 600 mg/L, respectively. The elevated TDS of northern valley unconfined and upper active confined systems result from mineral dissolution, ion exchange and methanogenesis of organic and evaporate lake sediments deposited in an ancient lake, herein designated as Lake Sipapu. Chemical evolutions along flow paths were modeled with NETPATH. Groundwater ages, and δ 13C, δ 2H and δ 18O compositions and distributions, suggest that mountain front recharge is the principle recharge mechanism for the upper and lower confined aquifers with travel times in the northern valley of more than 20,000 and 30,000 14C years, respectively. Southern valley confined aquifer travel times are 5,000 14C years or less. The unconfined aquifer contains appreciable modern recharge water and the contribution of confined aquifer water to the unconfined aquifer does not exceed 20%. 相似文献
19.
A conceptual groundwater flow model was developed for the crystalline aquifers in southeastern part of the Eastern region, Ghana. The objective was to determine approximate levels of groundwater recharge, estimate aquifer hydraulic parameters, and then test various scenarios of groundwater extraction under the current conditions of recharge. A steady state groundwater flow model has been calibrated against measured water levels of 19 wells in the area. The resulting recharge is estimated to range from 8.97 × 10 ?5 m/d to 7.14 × 10 ?4 m/d resulting in a basin wide average recharge of about 9.6% of total annual precipitation, which results in a basin wide quantitative recharge of about 2.4 million m 3/d in the area. This compares to recharge estimated from the chloride mass balance of 7.6% of precipitation determined in this study. The general groundwater flow in the area has also been determined to conform to the general northeast–southwest structural grain of the country. The implication is that the general hydrogeology is controlled by post genetic structural entities imposed on the rocks to create ingresses for sufficient groundwater storage and transport. Calibrated aquifer hydraulic conductivities range between 0.99 m/d and over 19.4 m/d. There is a significant contribution of groundwater discharge to stream flow in the study area. Increasing groundwater extraction will have an effect on stream flow. This study finds that the current groundwater extraction levels represent only 0.17% of the annual recharge from precipitation, and that groundwater can sustain future increased groundwater demands from population growth and industrialization. 相似文献
20.
Recently, Ras Sudr (the delta of Wadi Sudr) area received a great amount of attention due to different development expansion
activities directed towards this area. Although Quaternary aquifer is the most prospective aquifer in Ras Sudr area, it has
not yet completely evaluated. The present work deals with the simulation of the Quaternary groundwater system using a three-dimensional
groundwater flow model. MODFLOW code was applied for designing the model of the Ras Sudr area. This is to recognize the groundwater
potential as well as exploitation plan of the most prospective aquifer in the area. The objectives were to determine the hydraulic
parameters of the Quaternary aquifer, to estimate the recharge amount to the aquifer, and to determine the hydrochemistry
of groundwater in the aquifer. During this work, available data has been collected and some field investigation has been carried
out. Groundwater flow model has been simulated using pilot points’ method. SEAWAT has been also applied to simulate the variable-density
flow and sea water intrusion from the west. It can be concluded that: (1) the direction of groundwater flow is from the east
to the west, (2) the aquifer system attains a small range of log-transformed hydraulic conductivity. It ranges between 3.05
and 3.35 m/day, (3) groundwater would be exploited by about 6.4 × 10 6 m 3/year, (4) the estimated recharge accounts for 3 × 10 6 m 3/year, (5) an estimated subsurface flow from the east accounts for 2.7 × 10 6 m 3/year, (6) the increase of total dissolved solids (TDS) most likely due to dilution of salts along the movement way of groundwater
from recharge area to discharge area in addition to a contribution of sea water intrusion from the west. Moreover, it is worth
to note that a part of TDS increase might be through up coning from underlying more saline Miocene sediments. It is recommended
that: (1) any plan for increasing groundwater abstraction is unaffordable, (2) reliable estimates of groundwater abstraction
should be done and (3) automatic well control system should be made. 相似文献
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