ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb03032.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT:Irrigation permits in the Svartå River basin, Sweden, are issued with restricted validities by which irrigation is permitted only in those periods when the release from the primary regulation facility in the basin is greater than 2.0 m3/s. A “risk” measure describing the expected total duration of periods in which irrigation will not be permitted in the basin under a range of conditions has been formulated and applied to the basin. The measure recognizes only the period for which irrigation is not permitted and does not consider water availability as it is not a factor in this case. Comparison of the measure with a previously proposed approach shows that it provides a better measure of system behavior. The new measure is particularly useful for transferring to the nontechnical water user or manager an understanding of how well the overall irrigation system can be expected to per

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb03033.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT:Despite discontinuation of periodic National Water Assessments resulting from the dissolution of the Water Resources Council (WRC), information that assesses the Nation's water quantity and quality remains important to those involved in water resource management. However, citing limited apparent use of the WRC's Second National Water Assessment, some have implied that past assessments have been of minimal value to water resource management and policy. This has led to numerous suggestions for modifying the assessment process in the belief that such changes would increase the perceived value of future national water assessment efforts.This paper examines use of the Second National Water Assessment by water resource managers and decision makers. Based upon the individual and organizational characteristics of users, conclusions are drawn regarding the nature of national assessment use. The paper concludes that the primary value of national water assessment stems from the fact that it provides a unifyinggeneraldescription of the Nation's water resource situation and that it serves as a symbolic statement that a rational thought process guides national water policy. (KEY WORDS: National Water Assessment; information use; water planning; water policy; organizational decision making; logit analysis.)

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb03034.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT:The impacts of alternative forest watershed management practices are examined from a multicriterion viewpoint in order to select the most satisfactory management scheme. The selection process is carried out using two types of multicriterion decision making techniques: the outranking types of ELECTRE I and II, and the distance‐based type of compromise programming (CP). The process is illustrated using the U.S. Forest Service Beaver Creek Experimental Watershed in the Salt‐Verde River Basin of Arizona as an example. The desired objectives of the experimental study and the alternative forest watershed resources management schemes are transformed into an evaluation matrix of alternatives versus criteria array. Analyses of the matrix using the aforementioned techniques result in a complete preference ordering of the feasible alternatives in the cases of ELECTRE LI and CP and a partial ordering when ELECTRE I is used. In addition, some sensitivity analyses have been performed and showed ELECTRE II and CP to be fairly robust with respect to parameter changes, while ELECTRE I being highly sensitive to changes in threshold levels. Overall the three techniques pointed out that 65 percent vegetation cut is the best management scheme, while the next best is shown to be 50 percent vegetation

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb03035.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT:Juvenile specimens of largemouth bass, bluegill, and channel catfish were tested to determine their ability to withstand abrupt temperature decreases simulating the environmental impact from a sudden shutdown of a nuclear reactor during the winter. Temperature reductions were administered over 2‐hour and 24‐hour periods to assess the importance of the rate of temperature change and hence the mitigative value of having a holding pond with a one‐day retention time between the proposed cooling tower discharge and the receiving stream. Temperature decreases administered over a 2‐hour period resulted in much greater mortality than decreases of the same magnitude administered over a 24‐hour period. Thus, the value of a pond for mitigation from cold shock was substantiated. Results also indicated that adherence to the U.S. EPA temperature criteria for freshwater fish should provide adequate protection from c

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb03036.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT:The problem of determining the optimal route to operate a network of hydrometric gauges within a given area is formulated and solved by an original heuristic traveling salesman algorithm. The algorithm used for solving the problem takes into account the variation of station service time, the eight‐hour maximum working day, existence of more than one home base, and the budget constraint. The traveling salesman algorithm is used to solve the optima! assignment problem within a one‐day time limit, locating a starting base, stations to visit, and the closest home base. The ending base for the previous day becomes the starting base for the next day, and the assignment procedure is repeated. The computation proceeds from day to day, until all the stations in the considered region are serviced. The solution obtained presents the optimal route to operate a network of hydrometric gauges. The optimization procedure has been applied to the Dauphin hydrometric field area in Manit

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb03037.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT:A series of flume tests were conducted to determine the flow resistance of angular shaped riprap in steep channels. Flow resistance was expressed in terms of the Darcy‐Weisbach friction factor and the Manning's roughness coefficient. Prototype channels of 4 ft. (1.2 m) and 12 ft. (3.7 m) in width were constructed at slopes ranging from 0.01 to 0.20. The channel beds were comprised of angular riprap of median diameters of 1, 2, 4, 5, and 6 inches (2.59, 5.59, 10.41, 12.95, and 15.75 cms). The Darcy‐Weisbach and Manning's coefficients were determined for each test condition prior to bed failure.The resulting Darcy‐Weisbach coefficients were related to the channel energy gradient and the bed relative submergence for highly turbulent flow. Also, Manning's roughness coefficients were related to the product of the median stone diameter and energy gradient. Because of the angular shape of the riprap and the wedging and/or packing of the bed materials, the resistance to flow was found to exceed the flow resistance values predicted by previous studies. Expressions were presented for estimating the resistance to flow for angular riprap in steep cha

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb03038.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT:A typical single family residence in Tucson, Arizona, was retrofitted to incorporate low‐water‐use fixtures and water reuse systems. The use of municipal water was reduced by 53 percent to 53 gallons per capita per day (gpcd) and total water use at the home was reduced by 33 percent to 74 g

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb03039.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT:Stream channel development is a complicated process involving many factors. A major goal of research in fluvial geomorphology is to develop an understanding of the relations between channel form, water discharge, and sediment discharge characteristics. The concept of thresholds has been introduced as an element in fluvial processes, with the implication that the factors involved in a process might change in some way as threshold boundaries are passed. This study is focused on the extent to which a particular regional boundary represents a threshold in the process of stream channel development. Twenty‐four alluvial stream channels from the Great Plains region and 24 from the Central Lowlands region are compared with regard to the distributional form, central tendency and dispersion characteristics, and correlation structure of ten variables, including indicators of discharge, channel sediment, and channel morphology. The results suggest that these aspects of the data are very similar between the regions, except for certain differences in central tendency characteristics, which are assumed to reflect underlying differences between the regions in geology and climate. In general, the results support the idea that this regional boundary is not an effective threshold with respect to the stream channel development process, and that, therefore, stream channels develop in these environmentally distinct regions by way of a similar proces

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb03040.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT:The computer model, CREAMS, has been developed for field‐sized agricultural areas to aid in best management practices evaluation and planning. A test of CREAMS was performed by comparing monthly observed and simulated values for runoff, sediment, and phosphorus exports from two agricultural fields in Vermont to determine the applicability of the model in cold climates. Water quality samples were collected from field runoff and analyzed for both total suspended solids and total phosphorus. Generally, exports were overestimated during low flow months and underestimated during high flow months. Significant r2values (p<0.05), ranging from 0.78 to 0.90, between simulated and observed data were found for all comparisons except for sediment export from one field. Comparisons of the slopes of the regressions between observed and simulated values and the ideal slope of one using t‐tests revealed significant differences between simulated and observed monthly runoff, sediment, and phosphorus exports. It is postulated that this lack of adequate prediction could be attributed to the use of average monthly, instead of daily, temperature and solar radiation in calculations of evapotranspiration and snowmelt, and the use of static parameter values for parameters that vary seasona

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb03041.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY