ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1973.tb02950.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTMedian yield of wells in crystalline rocks of the Llano area is 14 gpm. Near the Highland Lakes the median yield is somewhat higher (17 gpm) owing to continuous recharge from the lakes. Domestic wells near the lakes are not as deep (median depth = 66 feet) as in the rest of the area (median depth = 76 feet). The major ground‐water supplies occur in granite grus and fractured granite.The yield per saturated foot of aquifer decreases with depth, owing to (1) the decreasing degree of weathering and hence of porosity and permeability with depth, and (2) the closing of fractures with depth. The decrease with depth of incremental yield is more marked in the Llano region than in the Sierra Nevada and in the eastern United States. Optimum depth of wells in the area is considered to be 75 to 100 feet. It is commonly more economical from the standpoint of well yield to drill several shallow wells rather than one deep well.Quality of ground water is generally good, but erratic, with median concentrations (in mg/l) of Si, 49; SO4, 61; Cl, 83; NO3, 21; Fe, 0.07; and total hardness (as CaCO3), 302. Schist generally yields water with higher total hardness and sulfate concentrations than other rock types. The water samples with high nitrate concentrations typically are from wells near septic systems or livestock pens. Even in ground water away from pollution sources the dissolved solids content tends to be higher than in water within crystalline rocks of other geographic area

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1973.tb02951.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTThe “ring average” method of generating trend surfaces has been applied to water chemistry data from shallow water wells in southern Illinois. The method is a slight modification of a well‐known geophysical technique. Basically the method acts as a filter which removes anomalies with dimensions smaller than the diameter of the ring. The trend maps generated by the technique are presented and discussed in this paper. Between the Salem‐Woodward structural block and the Wabash Valley Fault Zone water chemistry shows marked changes. These changes suggest that this is a zone of upward moving waters from deep stratigraphic units. The process of reverse osmosis filtration appears to explain some observed phenomena, but by no means all of them. The reasons why the bounding structural features are so effective is not clear

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1973.tb02952.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTThe purpose of this paper is to elucidate the phenomenon of brine upconing beneath a discharge well partially penetrating an unconfined aquifer in which fresh water is underlain by saline water. In order to predict the maximum uncontaminated fresh water production for given aquifer conditions and well geometry, the potential distribution in the flow region must be known. However, since the partial differential equation describing the flow is nonlinear and so are the boundary conditions, it is not possible to arrive at an exact analytic solution to the problem. Therefore, a less rigorous but tractable approach is to solve this problem using simplifying and physically plausible assumptions. A comparative study is made of the approximate analytic solutions available at the present time and the validity of the assumptions used is evaluated. Factors affecting the stability of the brine cone beneath a skimming well and conditions leading to entrainment of salt water along with fresh water production are also discussed.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1973.tb02953.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTAnalysis of drawdown data from either the pumped well or an observation well in a horizontal, wedge‐shaped aquifer results in determination of the distances from the well to the four nearest image wells.These results may be used, in the case of pumped‐well data alone, to determine the wedge angle; if only observation‐well data are used, eight possible positions of the wedge can be determined; a combination of pumped‐well and observation‐well data further reduces the number of possible wedge configurations to two, which are each other's mirror image in the line through the wells; only additional geologic or hydrologic information can distinguish between these two to delineate the aquifer area c

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1973.tb02954.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTThe design of small water systems requires the application of basic hydraulic principles. To prevent excessive head losses in piping systems created by pyramiding peak flows, the Cross method of successive approximations is used. This is a relatively simple means of checking the ability of the system to supply an adequate quantity of water at sufficient pressure. An example problem is worked out in detail to show how the method is applied to a trailer coach park water distribution system.Hydropneumatic storage tanks do not operate at maximum efficiency without prepressuring. Since Boyle's Law is applicable to all gases including air, it is used to determine the amount of prepressuring required to obtain the greatest amount of water from storage between pump cycles at predetermined pressure settings. A graph has been developed to determine the volume of water in a tank at various levels of prepressuring.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1973.tb02955.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTThis paper discusses the importance of starting an aquifer simulation from correct initial conditions. The errors that will arise if the simulation starts from zero or average heads are determined. Recommendations for minimizing these errors are made.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1973.tb02956.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1973.tb02957.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY