摘要:

ABSTRACT:In the past, development of Federal water resource projects depended heavily or exclusively on Federal financing of construction costs. However, pressures on the Federal budget, environmental issues, and the notion that there are economic efficiency gains when beneficiaries of Federal water resource projects increase their cost share are causing changes. The case of the Central Arizona Project Plan 6 is a noteworthy example of the transition to more non‐Federal participation in water resource development. This is because the non‐Federal financing is to be provided for a project already under construction. The negotiation and terms of the Plan 6 financing agreement between the Department of the Interior and multiple interests in Arizona are used as an example of how Federal water project cost sharing is in a state of transition. The negotiation process is described, a financial analysis is provided, and the terms of the agreement and policy issues that were deliberated in the Executive Branch of the Federal Government are discus

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1987.tb02949.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT:Current approaches to calculating discharge limitations and the use and intent of water quality standards are examined. Flow variable discharge permits, in which the amount of pollutant that may be discharged is based on the magnitude of the flow in the stream, are introduced as an alternative permit strategy that could reduce the cost of pollution control in certain instances while still meeting in‐stream water quality objectives. Several possible designs of flow variable discharge permits are presented to show the flexibility of the concept; for example, permits can be based on instantaneous flows, seasonal flows, trigger values, and ranges of flow

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1987.tb02950.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT:Competition for water, concerns for maintaining ground water quality, and compliance with legislative action require quantification of the water resource for high elevation watersheds in the Sierra Nevada. However, meager hydroclimatic data frequently hinder runoff assessments needed for formulating water development policies, and the selection of watershed models for estimating the water resource is limited to those requiring a minimum of observational data. A climatic water budget model and an energy slope and aspect model are employed to estimate the water resource for a small watershed in Sierra Valley north of Lake Tahoe. The models employ different assumptions and computational procedures, but the total water available estimated by both models is very similar. Measured runoff is estimated satisfactorily by the models, but streamflow is not representative of the total water resource because a substantial portion of the available water enters the regional ground water system. This conclusion is supported by hydrologic and geochemical evidence, and ground water recharge is estimated to be at least as great as measured runoff during dry years and nearly twice as large during wet years.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1987.tb02951.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT:The domestic sewage of the city of Beer‐Sheva, Israel, which is located in an arid region, is treated in a series of facultative ponds. The treated effluent is stored temporarily in an open surface earthen reservoir (about 0.5 ± 106m3in volume) and then used for irrigation. The effluent is applied via sprinkler and trickle irrigation systems. The main crops irrigated are cotton, wheat, alfalfa, and corn. Total cotton yield is over 5500 kg/ha, and the wheat grain yield is over 7500 kg/ha. The amount of effluent applied is about 6500 m3/ha for cotton (including preplant irrigation), and the wheat receives about 4500 m3/ha via irrigation and an additional 2000 m3/ha from precipitation. Due to the nutrient content in the effluent, the above yields are obtained without any additional fertilizati

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1987.tb02952.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT:Runoff and ground‐water samples were collected from four ombrotrophic bogs, representing undisturbed and drained/harvested conditions, at two‐week intervals during the summer of 1984. Analyses of samples for water quality parameters revealed significant (P<0.05 level) increases in specific conductance, NH4+‐N, total dissolved P, Mg, K, and Na and a decrease in the E4:E6ratio (suggesting increased proportions of humic acid) associated with drainage. There were no significant changes in dissolved organic carbon, Ca concentrations, or pH. Comparison of samples collected before, during, and after ditching showed increases in the dissolved organic carbon, NH4+‐N, total dissolved P, K, and Na and a decrease in the E4:E6ratio, but these changes were short lived; water quality returned to preditching values after about a week. The observed changes in water quality are small, probably because the peat is very acid (pH 3.0

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1987.tb02953.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT:The ground water quality of a shallow unconfined aquifer was monitored before and after implementation of a border strip irrigation scheme, by taking monthly samples from an array of 13 shallow wells. Two 30 m deep wells were sampled to obtain vertical concentration profiles. Marked vertical, temporal, and spatial variabilities were recorded. The monthly data were analyzed for step and linear trends using nonparametric tests that were adjusted for the effects of serial correlation. Average nitrate concentrations increased in the preirrigation period and decreased after irrigation began. This was attributed to wetter years in 1978–1979 than in 1976–1977 which increased leaching, and to disturbance of the topsoil during land contouring before irrigation, followed by excessive drainage after irrigation. Few significant trends were recorded for other determinants, possibly because of shorter data records.Nitrate, sulphate, and potassium concentrations decreased with depth, whereas sodium, calcium, bicarbonate, and chloride concentrations increased. These trends allowed an estimation to be made of the depth of ground water affected by percolating drainage. This depth increased during the irrigation season and after periods of winter recharge. Furthermore, an overall increase in the depth of drainage‐affected ground water occurred with time, which paralleled the development of the irrigation s

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1987.tb02954.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT:The production of a documentary video in a graduate seminar offers advantages over the traditional term paper. These advantages derive from the nature of the videotape medium. The most distinct difference between a written document and a video production is the use of the video camera to record events. In using the camera, the student is required to become involved both in front of the video camera, for example, as an interviewer, and behind the camera as a camera operator. Next, as an editor, the student is required to review the events that she/he has taped for inclusion in the final product. By participating in these three roles, the student has the opportunity to learn interviewing skills while interacting with professionals in the field, to learn videotaping skills, and to see him/herself as he/she appears to others. The student can use the video feedback to improve his/her professional presentation; posture, dress, gestures, speech, and facial expressions all have an impact on how we are perceived by others. Additionally, the painstaking process of reviewing the taped material leads to an intimate knowledge of the topic, and the process of choosing portions out of entire interviews hones the ability to select the crucial or central themes and ideas from any discussion. Finally, the power of video lies in its ability to communicate information to a wide audience. Although the nature of video for the general public does not permit highly detailed or rigorous coverage of any topic, it is a major source of information. Accordingly, video is an important tool that can be used to inform the public about the importance of wise water resource management.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1987.tb02955.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT:Coastal central California is a region that has never been the subject of tree‐ring studies. New tree‐ring chronologies developed from cores of big cone spruce (Pseudotusuga macrocarpa(Torr.) Mayr.) growing in the Transverse Ranges of central Santa Barbara county were used to reconstruct precipitation fluctuations for this region. To verify the new reconstructions, calibration with recorded rainfall using cross‐validation, comparison with other reconstructions, and documentary evidence from historical sources were utilized. The precipitation reconstructions show that there have not been fluctuations in mean precipitation on time scales longer than 30 years, but there have been major fluctuations in precipitation variability including changes in the frequency of extremes and rare events that have not occurred in the modern r

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1987.tb02956.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT:A soil erosion simulation model that considered the physical conditions of agricultural watersheds and that interfaced with the modified USDAHL‐74 watershed hydrology model was developed. The erosion model simulates the detachment and transport of soil particles caused by raindrop impact and overland flow from rill and interrill areas. The model considers temporal and spatial variation of plant residue, crop canopy cover, snow cover, and the moisture content of surface soil as modifying factors of the erosive forces of raindrop impact and overland flow. The hydrology model simulates overland flow and some of the physical parameters that are used in the erosion model. The simulation is executed in the time interval determined by the rainfall rate or snowmelt rate. The erosion model compares the transport capacity of the overland flow and the sediment loaded in the overland flow to determine the fate account for the free soil particles that have already been detached and are readily available to be transported by the overland flow. The model was tested with data from two small agricultural watersheds in the Palouse region of the Pacific Northwest dryland. The model was calibrated by trial‐and‐error to determine the coefficients of the

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1987.tb02957.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT:Laboratory microcosms were used to evaluate the effect of pH on release of soluble reactive phosphorus (SRP) during aerobic decomposition of the aquatic macrophyteEleocharissp., which is common in oligotrophic Florida lakes. The total amount of SRP released during a 227‐day incubation in the dark was independent of pH over the range 3.7 to 5.5, but initial rates of release were faster at the lowest pH. The results indicate that the low total phosphorus concentrations observed in many acidic lakes are not necessarily attributable to reduced rates of decomposition and nutrient mineralization at low pH, as some researchers have suggeste

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1987.tb02958.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY