摘要:

ABSTRACT:The use of nonparametric tests for monotonic trend has flourished in recent years to support routine water quality data analyses. The validity of an assumption of independent, identically distributed error terms is an important concern in selecting the appropriate nonparametric test, as is the presence of missing values. Decision rules are needed for choosing between alternative tests and for deciding whether and how to pre‐process data before trend testing. Several data pre‐processing procedures in conjunction with the Mann‐Kendall tau and the Seasonal Kendall test (with and without serial correlation correction) are evaluated using synthetic time series with generated serial correlation and missing data. A composite test (pre‐testing for serial correlation followed by one of two trend tests) is evaluated and was found to perform satisfa

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03168.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:The general relationship between water policy and social policy in the Western United States is examined by utilizing the example of the Arizona Groundwater Management Act. Too often, this is a relationship which goes largely unexamined, at least in any explicit way. In areas of perceived or real water scarcity, it is often the case that the setting of water policy severely constrains the social policy. Too many fundamental social policy issues are left to unstated assumptions through such a procedure. But, this paper asks, should not the social policy lead, and the water policy follow? In other words, in this relationship, which is the dog, and which is the tail?

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03169.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:Confined production of poultry results in significant volumes of waste material which are typically disposed of by land application. Concerns over the potential environmental impacts of poultry waste disposal have resulted in ongoing efforts to develop management practices which maintain high quality of water downstream of disposal areas. The timing of application to minimize waste constituent losses is a management practice with the potential to ensure high quality of streams, rivers, and lakes downstream of receiving areas. This paper describes the development and application of a method to identify which time of year is best, from the standpoint of surface water quality, for land application of poultry waste. The procedure consists of using a mathematical simulation model to estimate average nitrogen and phosphorus losses resulting from different application timings, and then identifying the timings which minimize losses of these nutrients. The procedure was applied to three locations in Arkansas, and three different criteria for optimality of application timing were investigated. One criterion was oriented strictly to water quality, one was oriented only to crop production, and the last was a combination. The criteria resulted in different windows of time being identified as optimal. Optimal windows also varied with location of the receiving area. The results indicate that it is possible to land‐apply poultry waste at times which both minimize nutrient losses and maximize crop yiel

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03170.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:Texans participate directly in water policy decision‐making through a referendum process involving amendment of the state's constitution. Prior to 1985, Texans voted on eight amendments. Five of these were ratified (1957, 1962, 1966, 1971, 1976), and collectively resulted in the creation of the Water Development Fund, with an authorization level of $600 million, and the Texas Water Development Board, the organization charged with administering the fund. Three other amendments were defeated in 1969, 1976, and 1981 by ever‐increasing margins. From 1985 to 1991, six additional amendments were proposed and subsequently ratified, resulting in a $1.8 billion increase in Water Development Fund authorization and the creation of an agricultural water conservation fund and bond insurance program. County‐level electoral data for the 1985–1991 referenda were mapped to assess sectional and regional factors underlying public opinion regarding these water resource development and funding programs. Regional contrasts were most pronounced for the 1989 and 1991 referenda that targeted economically distressed areas across the state, particularly the colonias located along the Rio Grande, and the 1989 amendment that removed a time limit on the issuance of agricultural water conservation bonds. As a specific case study, the Texas experience could serve as a guide in California where similar constitutional restrictions require tax and spending programs to be approved by voters, and in other states that may be considering the development of similar state‐level financial programs for water

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03171.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:Thirty‐five lakes in southern Labrador sampled in 1981 were resampled in 1989 and water chemistry values were compared between visits. Results showed higher pH, specific conductance, acid neutralization capacity, color, and base cations values in 1989, though sulfate, the ion most likely to reflect acid precipitation impacts, did not vary. The major ion changes measured were probably due to natural hydrological variations and not to changes in acid inputs.Results from the 1989 data showed a slight, but significant, decrease in water sulfate concentration trend from western to eastern Labrador, though most values, even in the western portion of the study area, fell close to the values considered “background” by Brakkeet at. (1989). Base cation concentrations exceeded those which could be predicted from weathering by carbonic and bicarbonic acid. Assuming that little weathering is generated by acid precipitation in this region, the excess cations measured are probably a result of bedrock dissolution from organic acids generated by plant decomposition. Calculations showed that organic acid effect could be responsible for 9 to 52 percent of total weathering in the study b

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03172.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:Infiltration trenches are an effective stormwater management alternative for the control of urban runoff from small areas. Perforated pipes buried within the gravel of an infiltration trench are used to distribute the inflowing runoff along the length of the trench. Laboratory tests are described that characterize the hydraulics of the orifices in perforated pipes. The results show that the steady‐state exfiltration of water from the pipe into a surrounding gravel trench can be described by the orifice equatio

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03173.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:A general methodology for fuzzy clustering analysis is developed and illustrated with a case study of water quality evaluation for Dianshan Lake, Shanghai, China. Fuzzy clustering analysis may be used whenever a composite classification of water quality incorporates multiple parameters. In such cases, the technique may be used as a complement or an alternative to comprehensive assessment. In fuzzy clustering analysis, the classification is determined by a fuzzy relation. After a fuzzy similarity matrix has been established and the fuzzy relation stabilized, a dynamic clustering chart can be developed. Given a suitable threshold, the appropriate classification is worked out. The methodology is relatively simple, and the results can be interpreted to provide valuable information to support decision making and to aid water quality management.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03174.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:An irrigation model based on a modified Thornthwaite water balance was used to simulate the effects of various hypothetical climatic changes on annual irrigation demand in a humidtemperate climate. The climatic‐change scenarios consisted of combinations of changes in temperature, precipitation, and stomatal resistance of plants to transpiration. The objectives were to (1) examine the effects of long‐term changes in these components of climatic change on annual irrigation demand, and (2) identify which of these factors would cause the largest changes in annual irrigation demand.Hypothetical climatic changes that only included increases in temperature and changes in precipitation resulted in increased annual irrigation demand, even with a 20 percent increase in precipitation. The model results showed that, for the ranges of changes in temperature and precipitation used in this study, changes in irrigation demand were more sensitive to changes in temperature than to changes in precipitation. Model results also indicated that increased stomatal resistance to transpiration counteracted the effects of increases in temperature and decreases in precipitation on irrigation demand. Changes in irrigation demand were even more sensitive to changes in stomatal resistance than to changes in temperature. A large amount of uncertainty is associated with predictions of future climatic conditions; however, uncertainty associated with natural climatic variability may be larger and may mask the effects of climatic change on irrigation dem

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03175.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:Simulated rainfall was used on experimental field plots to compare the effect of chemical fertilizer and sludge application on sediment, nitrogen, and phosphorus in runoff from no‐till and conventional tillage systems. Chemical fertilizer application under the no‐till system resulted in the least amount of total N and P in surface runoff. However, sludge application under the no‐till system resulted in the least amount of NO3‐N and sediment in surface runoff. The worst water quality scenarios were observed when either sludge or chemical fertilizer were surface‐applied under a conventional tillage system. Nitrogen losses from the conventional tillage system were minimized when sludge was incorporated into the soil. However, phosphorus and sediment yield from such a system were significantly higher when compared to phosphorus and sediment yield from the no‐till system.The results from this study indicate that the use of sludge on agricultural land under a no‐till system can be a viable alternative to chemical fertilizer for nitrogen and phosphorus control in runoff. A more cautious approach is recommended when the sludge is incorporated into the soil in a conventional tillage system because of potential for high sediment and phosphorus yield in s

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03176.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:This paper presents the results of an investigation of the effects of the Maryland Critical Area Act on generation of non‐point source loads of phosphorus, nitrogen, and sediment to the Rhode River estuary. The Simple Method model, the Marcus and Kearney regression model, and the CREAMS model were used to estimate annual loads under: (1) present conditions, (2) maximum land use development allowable under the Act, and (3) two sets of future land use conditions that might occur if the Act were not in place. Results indicate that the Critical Area Act can reduce the present generation of nonpoint nutrient and sediment loadings 20–30 percent from the regulated area. These reductions can occur while preserving agricultural lands and allowing limited residential and urban development. The decrease in nutrient loadings is primarily dependent upon implementation and enforcement of agricultural best management practices (BMPs). The BMPs could reduce present agricultural nutrient loadings by 90 percent to a level comparable to loadings from residential areas. The estimated effectiveness of the Critical Area Act is even greater when compared to potential future nutrient loadings if development in the area remains unregulated. Unrestricted residential and urban development could increase nutrient loadings by 200 percent to 1000 percent as compared to controlled development under Critical Area Act guidelines. The Critical Area Act primarily prevents these future increases by severely limiting woodland cutting, with lesser results obtained by requiring urban B

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03177.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY