Domestic Well Capture Zone and Influence of the Gravel Pack Length

Domestic wells in North America and elsewhere are typically constructed at relatively shallow depths and with the sand or gravel pack extending far above the intake screen of the well (shallow well seal). The source areas of these domestic wells and the effect of an extended gravel pack on the source area are typically unknown, and few resources exist for estimating these. In this article, we use detailed, high-resolution ground water modeling to estimate the capture zone (source area) of a typical domestic well located in an alluvial aquifer. Results for a wide range of aquifer and gravel pack hydraulic conductivities are compared to a simple analytical model. Correction factors for the analytical model are computed based on statistical regression of the numerical results against the analytical model. This tool can be applied to estimate the source area of a domestic well for a wide range of conditions. We show that an extended gravel pack above the well screen may contribute significantly to the overall inflow to a domestic well, especially in less permeable aquifers, where that contribution may range from 20% to 50% and that an extended gravel pack may lead to a significantly elongated capture zone, in some instances, nearly doubling the length of the capture zone. Extending the gravel pack much above the intake screen therefore significantly increases the vulnerability of the water source.     

地质构造与矿床之关系

本书共二百八十面,十面为索引。包括文章七十九篇,分由六十五人执笔。文章按其内容分属于六章,章名如次: 一、构造现象与矿床之数种关系二、大区域内与某种矿床有关之构造现象     

GIS-assisted classification of litho-geomorphological units using Maximum Likelihood Classification,Vipava Valley,SW Slovenia

In the Vipava Valley (SW Slovenia), various types of mass movements occur in a geologically and geomorphologically diverse setting. These comprise various types of landslides, creep, and Quaternary slope deposits of carbonate blocks and recent scree deposits. A general geological setting is represented as Mesozoic carbonate overthrust on Paleogene flysch (alternations of mostly sandstones and marlstones), resulting in steep slopes and mass movements. Our study is based on the automatic classification of various litho-geomorphological units including slope deposits, alluvial deposits, steep carbonate cliffs, flysch, two carbonate plateaus, and Quaternary deposits, based on supervised Maximum Likelihood Classification. Several polygons were used for training in the broader valley area, and later, the method was applied to automatically classify the complete area into the abovementioned six units. For input layers, we used data for elevation, slope, terrain ruggedness index (TRI), and curvature. Results show that generally, the method is suitable for classification of the litho-geomorphological units including slope deposits. However, comparison with a more detailed map, comprising mapped various mass movements indicated that the method correctly predicts high Trnovo plateau carbonates, steep carbonate slopes, translational carbonate blocks, and fossil rock avalanche deposits, and alluvial deposits, but is not able to clearly distinguish between flysch and more recent slope deposits of gravel and breccia due to their similar elevation, TRI, and slope values. The Slano blato mudflow and Stogovce landslide are not recognized. Therefore, this automatic classification can be carefully used to create a guidance map of general occurrences of litho-geomorphological units including slope deposits before going to the field, with the aim of delineation of slope deposits so they can be further studied in detail later in the field. However, such a map cannot be used as a direct substitute map for the geological and geomorphological map obtained in the field due to impossibility in distinguishing among the units with the same properties (elevation, slope, and TRI values).     

探地雷达探测地下管线的能力

这是作者摘编的有关探地雷达探测管线的一些资料。通过细致的实验,从中分析管线的粗细、材质、充填物、缺损情况及天线频率、噪音等对雷达图像的影响,对今后开展城市管线探地雷达调查工作会有所帮助。     

Horizontal Slow Oscillation of a Moored Tanker and Numerical Method of Hopf-Bifurcation

- In this paper, a six-order nonlinear dynamic model with three degrees of freedom is presented for the study of the "fishtail" motion of a Single Point Mooring System. The effect of parameter variations on the equilibrium state of the system is analized. In order to study the stability of the equilibrium state, the mooring-line length / is chosen as a bifurcation parameter, so that all eigenvalues of the Jacobian matrix under different parameters can be worked out, and then the Hopf-bifurcation point can be found . Finally, the Hopf-bifurcation periodic solution of the system is computed.