Characteristics of shallow geothermal fields in major cities of Tibet Autonomous Region     

YANG Hai-jun  DONG Jian-xing  SUN Dong  HUANG Rui 《地下水科学与工程》2014,7(1):77-85

Based on the project titled “Investigation and evaluation of shallow geothermal energy in major cities of Tibet Autonomous Region”, the distribution characteristics and occurrence conditions of shallow geothermal fields in these cities were introduced in this paper. To this end, relevant data in Lhasa, Shigatse and Nyingchi Cities through vertical thermometry was a focus, so as to analyze groundwater temperature and the distribution law of strata with constant temperature. Then through comprehensive comparisons and analysis of the relationship between groundwater temperature and climate, differences in this aspect of Nagqu City were taken as a typical case to clarify formation of geothermal field and corresponding influence on groundwater temperature, furthermore providing basic data for rational development and utilization of shallow geothermal energy in Tibet Autonomous Region.  相似文献   

Quantifying groundwater discharge to a small perennial stream in southern Ontario, Canada   总被引：3，自引：0，他引：3  

Edwin E. Cey  David L. Rudolph  Gary W. Parkin  Ramon Aravena 《Journal of Hydrology》1998,210(1-4):21-37

A study of the interaction between groundwater and surface water was undertaken within a small agricultural watershed in southern Ontario, Canada. Groundwater contributions to streamflow were measured along a section of stream during baseflow conditions and during rainfall events. Four techniques were used to estimate the contribution of groundwater to the stream along a 450 m reach (three during baseflow and one during stormflow conditions). Under baseflow conditions, streamflow measurements using the velocity–area technique indicated that the net groundwater flux to the stream during the summer months was 10 ml s⁻¹ m⁻¹. Hydrometric measurements (i.e. hydraulic gradient and hydraulic conductivity) taken using mini-piezometers installed in the sediments beneath the stream resulted in net groundwater flux estimates that were four to five times lower. Seepage meters failed to provide any measurements of water flux into or out of the stream. Therefore, based on these results, the velocity–area technique gives the best estimate of groundwater discharge. Hydrograph separations were conducted using isotopic ratios and electrical conductivity on two large rainfall events with different antecedent moisture conditions in the catchment. Both events showed that pre-event water (generally considered groundwater) dominated streamflow and tile drain flow with 64%–80% of the total discharge contributed by pre-event water. High water table conditions within the catchment resulted in greater stream discharge and a greater contribution of event water in the streamflow than that observed under low water table conditions for similar intensity storm events. The results also showed that differences in riparian zone width, vegetation and surface saturation conditions between the upper and lower catchment can influence the relative magnitude of streamflow response from the two catchment areas.  相似文献   

共和7.0级地震前地下流体前兆的动态演化特征   总被引：3，自引：1，他引：2       下载免费PDF全文

刘耀炜  张元生 《地震工程学报》1998,20(1):59-64

使用40个地下流体观测点的资料,对1990年4月26日青海省共和M_S7.0地震的前兆动态特征进行了系统研究.结果表明:(1)地震带内观测点的水氡趋势异常及水化、水位群体异常及频次异常与断层平均形变速率呈同步变化.地下流体群体异常频次的累加值曲线在地震前表现为指数加速变化图形.(2)震源外围240km范围内的水氡中短期趋势上升异常,表现为由震源逐渐向外围扩散的特点.在短临阶段各测点水氡的异常变化基本同步.(3)流体短临前兆出现明显的起伏加剧和层次现象,突出的表现是流量、断层气日变化在临震阶段出现3次加剧,且异常幅度一次高于一次.  相似文献   

Early-indicator signals of groundwater contamination: the case of seawater encroachment   总被引：4，自引：0，他引：4  

A. J. Melloul  L. C. Goldenberg 《Environmental Geology》1998,33(4):279-288

 An early indication of groundwater contamination occurs when pollutant concentrations start to fluctuate and exceed background values of ambient fresh groundwater. An analysis of a characteristic situation of this type uses data from Israel's coastal phreatic granular aquifer. The pollutant is generally seawater, and the contamination process involves replacement of freshwater by encroaching sea- or other saltwater, a process augmented by human activity. The contamination process involves three stages: (1) groundwater composition remains relatively stable with small salinity content; (2) small salinity changes are perceptible with reversible fluctuations; and (3) salinity concentration increases at a sharply higher rate. The second stage is a useful early-indicator signal of contamination. Early-indicator signals of groundwater pollutant concentrations involve "minor" fluctuations in water chemistry at the advent of the contamination process. The intensity and magnitude of such a salinization/pollution process at any given location depends upon lithologic matrix, aquifer heterogeneity, and resultant flow domain characteristics, as well as contaminant properties. If such "signs" are detected at a sufficiently early stage, appropriate management steps may be taken to rectify further seawater and/or saltwater encroachment. Received: 23 July 1996 · Accepted: 25 June 1997  相似文献   

拉尔玛金矿的生物成矿作用   总被引：1，自引：0，他引：1  

帅德权  胡晓强 《甘肃地质》1998,7(2):81-86

位于甘、川两省交界处的拉尔玛金矿床,赋存于下寒武统太阳顶群,矿区内岩浆活动不强烈,矿床中断裂构造较发育,矿石矿物种类较齐全。矿石中的生物有机地球化学特征表明其为细菌和低等藻类生物体衍生的生物标志物和遗传特征,证明了太阳顶群中的有机质起源于菌藻类生物。矿石中的金属矿物生物组构有生物有机胶体组构和矿交代生物组构,说明生物成矿作用经历了直接成矿和间接成矿,即两轮聚矿作用,菌藻生物的第一轮聚金主要形成矿源层,生物的两轮聚金结果,形成此矿床。  相似文献   

宝鸡市狄家坡滑坡稳定性研究   总被引：13，自引：1，他引：12  

刘传正  急正盛 《工程地质学报》1998,6(2):103-113

宝鸡市狄家坡斜坡是一个古滑坡。在调查滑坡区水文地质和工程地质条件的前提下, 本文描述了滑坡的形态与物质结构、滑坡表层的变形破坏特征及其影响因素, 探讨了古滑坡的发生机制。引用可以任意条分块体的Sarma方法, 研究了该滑坡在自然、地震、饱水和三者同时存在共四种状态下的稳定性, 并进行了斜坡表层黄土坡体的稳定性对于地下水位上升的敏感性分析。基本结论是, 狄家坡滑坡在整体上是稳定的, 其表层的黄土坡体在地下水位上升时会发生失稳破坏。最后, 提出了进行滑坡防治的工程对策。  相似文献   

Groundwater for urban water supplies in northern China – An overview     

Han Zaisheng 《Hydrogeology Journal》1998,6(3):416-420

 Groundwater plays an important role for urban and industrial water supply in northern China. More than 1000 groundwater wellfields have been explored and installed. Groundwater provides about half the total quantity of the urban water supply. Complete regulations and methods for the exploration of groundwater have been established in the P.R. China. Substantial over-exploitation of groundwater has created environmental problems in some cities. Some safeguarding measures for groundwater-resource protection have been undertaken. Received, August 1997 · Revised, February 1998 · Accepted, April 1998  相似文献   

Groundwater resources in the Jabal Al Hass region,northwest Syria: an assessment of past use and future potential   总被引：2，自引：1，他引：1  

Elco Luijendijk  Adriana Bruggeman 《Hydrogeology Journal》2008,16(3):511-530

In many cases, the development of groundwater resources to boost agricultural production in dry areas has led to a continuous decline in groundwater levels; this has called into question the sustainability of such exploitation. In developing countries, limited budgets and scarce hydrological data often do not allow groundwater resources to be assessed through groundwater modeling. A case study is presented of a low-cost water-balance approach to groundwater resource assessments in a 1,550 km² semi-arid region in northwestern Syria. The past development of irrigated agriculture and its effect on the groundwater system were studied by analysis of Landsat images and long-term groundwater level changes, respectively. All components of the groundwater balance were determined. Groundwater recharge was estimated using the chloride mass balance method. Over the past three decades, groundwater levels have declined, on average, 23 m, coinciding with a two-fold increase in the groundwater-irrigated area. Groundwater resources are currently depleted by a value that lies between 9.5×10⁶ and 118×10⁶ m³ year^?1, which is larger than can be compensated for by a future decrease in natural discharge or changes in boundary conditions. However, groundwater resources are likely to be sufficient to supply domestic and livestock needs in the area.  相似文献   

Geochemical Eccentricity of Ground Water Allied to Weathering of Basalts from the Deccan Volcanic Province,India: Insinuation on CO<Subscript>2</Subscript> Consumption     

N. J. Pawar  J. B. Pawar  Suyash Kumar  Ashwini Supekar 《Aquatic Geochemistry》2008,14(1):41-71

Analyses of 72 samples from Upper Panjhara basin in the northern part of Deccan Plateau, India, indicate that geochemical incongruity of groundwater is largely a function of mineral composition of the basaltic lithology. Higher proportion of alkaline earth elements to total cations and HCO₃>Cl + SO₄ reflect weathering of primary silicates as chief source of ions. Inputs of Cl, SO₄, and NO₃ are related to rainfall and localized anthropogenic factors. Groundwater from recharge area representing Ca + Mg–HCO₃ type progressively evolves to Ca + Na–HCO₃ and Na–Ca–HCO₃ class along flow direction replicates the role of cation exchange and precipitation processes. While the post-monsoon chemistry is controlled by silicate mineral dissolution + cation exchange reactions, pre-monsoon variability is attributable chiefly to precipitation reactions + anthropogenic factors. Positive correlations between Mg vs HCO₃ and Ca + Mg vs HCO₃ supports selective dissolution of olivine and pyroxene as dominant process in post-monsoon followed by dissolution of plagioclase feldspar and secondary carbonates. The pre-monsoon data however, points toward the dissolution of plagioclase and precipitation of CaCO₃ supported by improved correlation coefficients between Na + Ca vs HCO₃ and negative correlation of Ca vs HCO₃, respectively. It is proposed that the eccentricity in the composition of groundwater from the Panjhara basin is a function of selective dissolution of olivine > pyroxene followed by plagioclase feldspar. The data suggest siallitization (L < R and R _k) as dominant mechanism of chemical weathering of basalts, stimulating monosiallitic (kaolinite) and bisiallitic (montmorillonite) products. The chemical denudation rates for Panjhara basin worked out separately for the ground and surface water component range from 6.98 to 36.65 tons/km²/yr, respectively. The values of the CO₂ consumption rates range between 0.18 × 10⁶ mol//km²/yr (groundwater) and 0.9 × 10⁶ mol/km²/yr (surface water), which indicates that the groundwater forms a considerable fraction of CO₂ consumption, an inference, that is, not taken into contemplation in most of the studies.  相似文献   

Groundwater flow modeling for effective implementation of landslide stability enhancement measures     

H. K. Shrestha  R. Yatabe  N. P. Bhandary 《Landslides》2008,5(3):281-290

This paper deals with groundwater hydrology at a prominent fracture zone landslide slope (Nuta–Yone landslides) in Japan with an objective to explore an efficient method for the application of landslide stability enhancement measures. The correlation analyses between the hydrological parameters and ground surface movement data at this landslide resulted in low correlation values indicating that the geological formation of the area is extremely complex. For the purpose of understanding the groundwater flow behavior in the landslide area, a three-dimensional transient groundwater flow model was prepared for a part of the landslide slope, where the levels of effectiveness of applied landslide stability enhancement measures (in the form of multilayered deep horizontal drains) are different, and was calibrated against the measured water surface elevations at different piezometer locations. The parameter distributions in the calibrated model and the general directions of the groundwater flow in terms of flow vectors and the results of particle tracking at the model site were interpreted to understand the reasons for variations in effectiveness of existing landslide stability enhancement measures and to find potentially better locations for the implementation of future landslide stability enhancement measures. From the modeling results, it was also understood that groundwater flow model can be effectively used in better planning and locating the landslide stability enhancement measures.  相似文献