bluuebunny/crossref_metadata_2025 huggingface dataset:
MODEL FOR PREDICTING TRANSPORT OF PESTICIDES AND THEIR METABOLITES IN THE UNSATURATED ZONE1
Authors: Tim U.S. , Mostaghimi S.
Published: June 2007

ABSTRACT: A finite element model based on Galerkin's upstream weighted residual technique was developed to predict the simultaneous convective‐dispersion transport and transformations of pesticides and their metabolites in the unsaturated zone. Transformations of the parent compound and its metabolites were assumed to be first‐order reactions for oxidation and hydrolysis, while adsorption of the pesticide species (parent compound and metabolites) to the soil components was assumed to be represented by a linear equilibrium (Freundlich type) isotherm. Volatilization and plant root uptake of pesticides in the solution phase were neglected in the analysis. The proposed model was used to simulate the transport and transformation of aldicarb and its metabolites, aldicarb sulfoxide and aldicarb sulfone, in the soil profile. Several examples are used to demonstrate the accuracy, validity, and applicability of the proposed model. Simulated results indicate that the proposed model can potentially be used to estimate the mass flux of water, and pesticide and pesticide metabolite concentrations in the subsurface environment. However, further verification of the model against actual field data is needed to fully demonstrate the model's potential.
ECONOMIC EFFECTS OF SOIL CONDITIONS ON FARM STRATEGIES TO REDUCE AGRICULTURAL POLLUTION1
Authors: Roka Fritz M. , Lessley Billy V. , Magette William L.
Published: June 2007

ABSTRACT: Utilizing predictions of pollutant movement generated by the CREAMS model, the economics of reducing field losses of sediment and nitrate percolation were compared between two soil types on each of two slopes common to the Upper Eastern Shore of Maryland. The soils considered were Matapeake silt loam and Sassafras sandy loam textures on field slopes of 3.5 percent and 7.5 percent. A representative cash grain farm was used as a basis of comparison. Under assumptions of profit maximization, economic optimal cropping systems varied by slope. Results further indicated that relative cost‐effectiveness of sediment or nitrate percolation control varied by soil type for both slopes considered. Unit costs of sediment control were less on silt loam soils, while unit costs of nitrate percolation control were less on sandy loam soils.
FLUVIAL SEDIMENT STORAGE IN WETLANDS1
Authors: Phillips Jonathan D.
Published: June 2007

ABSTRACT: The important ecological and hydrological roles of wetlands are widely recognized, but the geomorphic functions of wetlands are also critical. Wetlands can be defined in geomorphic, as well as in hydrological or biological terms, and a geomorphic definition of wetlands is proposed. An analysis of fluvial sediment budget studies shows that wetlands typically serve as short‐term sediment sinks or longer‐term sediment storage sites. In ten study basins of various sizes, an estimated 14 to 58 percent of the total upland sediment production is stored in alluvial wetland or other aquatic environments. Of the sediment reaching streams, 29 to 93 percent is stored in alluvial wetland or channel environments. For basins of more than 100 km2, more than 15 percent of total upland sediment production and more than 50 percent of sediment reaching streams is deposited in wetlands. The data underestimates the magnitude of wetland sediment storage due to the lack of data from large river systems. A theoretical analysis of river channel sediment delivery shows that wetland and aquatic sediment storage is inevitable in fluvial systems and systematically related to basin size. Results suggest that wetlands should be managed in the context of drainage basins, rather than as discrete, independent units.
EVALUATION OF SOME APPROACHES TO ESTIMATING NON‐POINT POLLUTANT LOADS FOR UNMONITORED AREAS1
Authors: Richards R. Peter
Published: June 2007

ABSTRACT: Evaluation of the non‐point source pollutant load entering a lake from multiple tributaries requires either that all tributaries be monitored or that some extrapolation method be used to estimate loads originating in areas not monitored. Unmonitored areas include not only watersheds of tributaries that are not monitored, but also portions of a monitored tributary's drainage basin downstream from the monitoring site and areas of direct drainage. Significant portions of large lake drainage basins are often not monitored, and loads for these areas are often estimated by extrapolation. Six simple extrapolation procedures were evaluated by using them to estimate loads for areas that had been monitored and comparing the estimated loads with the monitored loads. Three approaches were based on inter‐basin ratios of area, C‐factor, and discharge. The other approaches used regression relationships between concentration and flow to estimate concentrations for the unmonitored basin. The ratio approaches generally were more reliable than the regression approaches. However, extrapolation by any method tested was not very precise. Some methods also were biased when applied to watersheds of a size different than the monitored one. Extrapolation by any of these methods would compromise the precision of the lake‐wide load estimate, if the unmonitored area were a significant part of the entire basin.
ESTIMATING MEAN AND VARIANCE FOR ENVIRONMENTAL SAMPLES WITH BELOW DETECTION LIMIT OBSERVATIONS1
Authors: Newman Michael C. , Dixon Philip M. , Looney Brian B. , Pinder John E.
Published: June 2007

ABSTRACT: Left‐censoring of data sets complicates subsequent statistical analyses. Generally, substitution or deletion methods provide poor estimates of the mean and variance of censored samples. These substitution and deletion methods include the use of values above the detection limit (DL) only, or substitution of 0, DL/2 or the DL for the below DL values during the calculation of mean and variance. A variety of statistical methods provides better estimators for different types of distributions and censoring. Maximum likelihood and order statistics methods compare favorably to the substitution or deletion methods. Selected statistical methods applicable to left‐censoring of environmental data sets are reviewed with the purpose of demonstrating the use of these statistical methods for coping with Type I (and Type II) left‐censoring of normally and log‐normally distributed environmental data sets. A PC program (UNCENSOR) is presented that implements these statistical methods. Problems associated with data sets with multiple DLs are discussed relative to censoring methods for life and fatigue tests as recently applied to water quality data sets.
A NEW LOOK AT FLOOD RISK DETERMINATION1
Authors: Booy C. , Lye L.M.
Published: June 2007

ABSTRACT: The probability distributions of annual peak flows used in flood risk analysis quantify the risk that a design flood will be exceeded. But the parameters of these distributions are themselves to a degree uncertain and this uncertainty increases the risk that the flood protection provided will in fact prove to be inadequate. The increase in flood risk due to parameter uncertainty is small when a fairly long record of data is available and the annual flood peaks are serially independent, which is the standard assumption in flood frequency analysis. But standard tests for serial independence are insensitive to the type of grouping of high and low values in a time series, which is measured by the Hurst coefficient. This grouping increases the parameter uncertainty considerably. A study of 49 annual peak flow series for Canadian rivers shows that many have a high Hurst coefficient. The corresponding increase in flood risk due to parameter uncertainty is shown to be substantial even for rivers with a long record, and therefore should not be neglected. The paper presents a method of rationally combining parameter uncertainty due to serial correlation, and the stochastic variability of peak flows in a single risk assessment. In addition, a relatively simple time series model that is capable of reproducing the observed serial correlation of flood peaks is presented.
COARSE WOODY DEBRIS AND CHANNEL MORPHOLOGY: A FLUME STUDY1
Authors: Cherry J. , Beschta R.L.
Published: June 2007

ABSTRACT: In recent years, logs and other structures have been added to streams for the purposes of altering channel morphology to improve fish habitat. This flume study was conducted to evaluate the effects of coarse woody debris on local channel morphology. Wooden dowels were used to simulate the effects of individual logs in a stream, and scour depth and surface area were determined at the end of each test run. The maximum scour depth was significantly correlated (90 percent confidence level) with both the vertical orientation of the dowels and the channel opening ratio; the scour surface area was significantly correlated (90 percent confidence level) with both the flow depth and the vertical orientation. Upstream‐oriented dowels caused relatively large streambed scour and also deflected flows toward the streambank. Downstream‐oriented dowels generally caused less bed scour and appeared to provide better bank protection because flow was generally deflected from the bank. In conjunction with data from field studies, these results provide information on the effects of orientation, hydraulic function, and relative stability of coarse woody debris in streams.
CHARACTERISTICS OF EXTREME PRECIPITATION1
Authors: Chang Tiao J.
Published: June 2007

ABSTRACT:Records of extreme precipitation were investigated using the Discrete Autoregressive Moving Average (DABMA) process, which can explain long persistences of wet and dry spells that exist in daily precipitation data. The results show that the daily precipitation with strong autocorrelation is inclined to be better fit by a Discrete Autoregressive (DAB) model. On the other hand, those data with weak autocorrelations tend to be best fit by a Discrete Moving Average (DMA) model. It can also be concluded that based on the records from extremely wet and dry regions there is no geographic preference regarding the selection of the best model.
ESTIMATING THE WATER QUALITY BENEFITS FROM SOIL EROSION CONTROL1
Authors: Ribaudo Marc O. , Young C. Edwin
Published: June 2007

ABSTRACT: A framework for estimating the water quality benefits from soil erosion was developed. The framework is based on the linkages between soil erosion and offsite damages. The linkages are: erosion on the field, movement of eroded materials to waterways, impact of discharged material on water quality parameters, impact of water quality changes on ability of water to provide economic services, and the economic value of the changes in water use. These linkages need to be modeled in order to estimate the water quality benefits from reductions in soil erosion. Methods for modeling each link on a geographic level, which enables the analyses of national soil conservation, were examined. Areas where data or models were found to be lacking include transport of sediment and nutrients to water systems, impact of discharged materials on water quality parameters, and impact of water quality on ability of water to provide economic services. An economic evaluation of 1983 soil conservation programs was presented as an example of how the framework could be used. A number of simplifying assumptions were made to represent links that could not be modeled with available data.
GROUND WATER MONITORING FOR TEMIK (ALDICARB) IN FLORIDA1
Authors: Miller W. L. , Foran J. A. , Huber W. , Davidson J. M. , Moye H. A. , Spangler D. P.
Published: June 2007

ABSTRACT: Over 700 community drinking water supplies were sampled for the pesticide Temik (aldicarb and its oxidative metabolites aldicarb sulfoxide and aldicarb sulfone) in Florida. All community supply wells sampled for Temik were located in counties where Temik was reported to have been used and approximately one‐half of the wells were located in counties where ground water was determined to be highly susceptible to contamination by Temik. Susceptibility was determined using ranking criteria that incorporated ground water recharge characteristics, water use, and Temik use patterns.

Temik was not detected in any of the community supply wells sampled during the study. However, Temik was detected in shallow, private wells, as was the pesticide ethylene dibromide in counties with ground water characterized as highly susceptible to contamination.
SIMULATION OF THE EFFECTS OF URBANIZATION ON BASIN STREAMFLOW1
Authors: Ng H. Y. F. , Marsalek J.
Published: June 2007

ABSTRACT: The hydrologic modeling of streamflow in the Waterford River Basin has been conducted as part of comprehensive investigations of the effects of urbanization on water resources in the basin. Using a detailed input data base, continuous simulation of streamflow in the study area has been done by means of the HSPF model, which has been calibrated for the existing conditions and then applied to several future land use scenarios. The basin climate and geology contribute to high conversion of precipitation into streamflow under the existing conditions. Consequently, future urban development in the study basin should not increase the annual streamflow, but would contribute to increases in peak flows and the incidence of flooding because of the increased speed of runoff. If the impervious area in the basin is doubled, the peak flows may increase by about 20 percent.
COMPARISON OF METHODS FOR ESTIMATING FLOOD MAGNITUDES ON SMALL STREAMS IN GEORGIA1
Authors: Hess Glen W. , Price McGlone
Published: June 2007

ABSTRACT: The U.S. Geological Survey has collected flood data for small, natural streams at many sites throughout Georgia during the past 20 years. Flood‐frequency relations were developed for these data using four methods: (1) observed (log‐Pearson Type HI analysis) data, (2) rainfall‐runoff model, (3) regional regression equations, and (4) map‐model combination. The results of the latter three methods were compared to the analyses of the observed data in order to quantify the differences in the methods and determine if the differences are statistically significant. Comparison of regression‐estimates with observed discharges for sites having 20 years (1966 to 1985) and 10 years (1976 to 1985) of record at different sites of annual peak record indicate that the regression‐estimates are not significantly different from the observed data. Comparison of rainfall‐runoff‐model simulated estimates with observed discharges for sites having 10 years and 20 years of annual peak record indicated that the model‐simulated estimates are significantly and not significantly different, respectively. The biasedness probably is due to a “loss of variance” in the averaging procedures used within the model and the short length of record as indicated in the 10 and 20 years of record. The comparison of map‐model simulated estimates with observed discharges for sites having 20 years of annual‐peak runoff indicate that the simulated estimates are not significantly different. Comparison of “improved” map‐model simulated estimates with observed discharges for sites having 20 years of annual‐peak runoff data indicate that the simulated estimates are different. The average adjustment factor suggested by Lichty and Liscum to calculate the “improved” map‐model overestimates in Georgia by an average of 20 percent for three recurrence intervals analyzed.
PRECIPITATION CATCH MEASURED BY TUE WYOMING SHIELD AND TUE DUAL‐GAGE SYSTEM1
Authors: Hanson Clayton L.
Published: June 2007

ABSTRACT: The Wyoming shield and dual‐gage measuring systems were developed to measure all precipitation, but more specifically snowfall under windy conditions. Results of a study at five sites on the Reynolds Creek Experimental Watershed in southwest Idaho indicate that gages with Wyoming shields and the dual‐gage system measured the same amount when air temperatures were higher than −2.2°C. Precipitation amounts computed from the dual. gage system were slightly more than from gages with Wyoming shields for snowfall, especially under windy conditions. Results also show how well the Alter shielded and unshielded gages used in the dual‐gage system represent the computed catch if data were only available from one or the other of the gages.
THE IMPACT OF STOCKWATERING PONDS (STOCKPONDS) ON RUNOFF FROM LARGE ARIZONA WATERSHEDS1
Authors: Mime Michael M. , Young Don W.
Published: June 2007

ABSTRACT: Major water rights adjudications involving the Little Colorado River Basin and Gila River Basin are presently underway within Arizona. Water resource managers are faced with the prospect of evaluating and regulating tens of thousands of water diversions and uses. Stockponds comprise a large percentage of the total number of water diversions within these basins. Water balance studies conducted on the Little Colorado River watershed above Lyman Lake and on the Gila River watershed above Solomon, Arizona, indicate that the impact of stockponds on the water available to downstream users is insignificant when compared to total watershed production. Considering that there are an estimated 25,000 stockponds in the Gila River basin alone, rigorous case‐by‐case investigations and stringent regulation of individual stockponds may be impractical and unwarranted. Therefore, stock‐pond claims within the context of the general adjudication process may be effectively handled by partial summary judgment, thereby allowing the court to concentrate on major water users and water rights issues.
BRUSHLAND MANAGEMENT FOR INCREASED WATER YIELD IN TEXAS1
Authors: Griffin Ronald C. , McCarl Bruce A.
Published: June 2007

ABSTRACT: Policies to encourage brush management are under consideration as a means to address the water scarcity issue in Texas. Additional water can be generated by treating some of the 100‐million‐plus acres of brush‐infested rangelands in Texas. Evidence of water yield benefits are, however, tentative at this time. Economic investigations based on available data show the potential desirability of brush management but also show benefits to be critically dependent on added water yield, value, and cost‐sharing policy. Wildlife, water rights, and environmental issues are also important considerations. The lack of research information on likely impacts makes it difficult to choose among alternative policies for encouraging brush management. More research on this potential opportunity is needed.
MANGANESE OXIDATION RELATED TO THE RELEASES FROM RESERVOIRS1
Authors: Gordon John A.
Published: June 2007

ABSTRACT: Stratified reservoir waters frequently contain objectionable quantities of dissolved manganese. The oxidation and removal of dissolved manganese during transport below Normandy Dam, Tennessee, was shown to be much more rapid than expected from chemical oxidation. Oxidation took place in only a day of travel time rather than months or years. Laboratory studies showed that removal was associated with a slime found on rock surfaces below the dam and led to the development of column technology as a possible method of treating natural waters containing manganese. Hydraulic loadings on the columns in the range of 390–780 m3/hr.ha accomplished a 90 percent removal rate of soluble manganese over an influent concentration range of 2 to 15 mg/l.
ECONOMIC FRAMEWORK FOR FLOOD AND SEDIMENT CONTROL WITH DETENTION BASINS1
Authors: Moglen Glenn E. , McCuen Richard H.
Published: June 2007

ABSTRACT: A framework for combining economic factors and the hydrolo of detention basins is provided. The general development of economic production functions for water quality (sediment) and flood control is discussed. Example production functions are generated to compare water quality (sediment control only) and flood control. For the given example, the design of a detention basin for downstream sediment control is economically unwarranted. When compared to on‐site detention facilities, regional detention structures appear to be more practical from an economic standpoint for water quality control. Since sediment was the only water quality parameter assessed, it is entirely possible that the design of a detention basin for water quality control would be justified if the effects of all pollutants of concern could be quantified. Policy aspects of detention facilities that relate to the economics of water quality control are also discussed.
THE EFFECTS OF ARTIFICIAL CIRCULATION ON A HYPEREUTROPHIC LAKE1
Authors: Osgood Richard A. , Stiegler Jonathan E.
Published: June 2007

ABSTRACT: Crystal Lake, a small urban lake in Robbinsdale, MN, had been artificially circulated for 12 years before a detailed water quality evaluation was undertaken. In 1986, the circulation system was shut off for a two‐year assessment. Although the lake remained hypereutrophic, the use of the lake, which included shoreline fishing and feeding ducks and geese, did not appear to be seriously impaired by the absence of artificial circulation. The circulation system was returned to service in October 1987 (there are 16 diffusers in this 0.31 km−2 lake). Continuous limnological data from October 1987 through October 1988, plus several sampling dates in 1989, compares to the two non‐circulation years (1986 and 1987) as follows: there was a two‐ to three‐fold increase in the lake's concentration of total phosphorus, total Kjeldahl nitrogen, and chlorophyll and a similar decrease in Secchi disk transparency. The surface oxygen concentration was reduced and the deep waters were nearly anoxic. In fact, following a wind storm in 1988, the entire lake became anoxic due to the mixing of high BOD throughout the water column, and a summertime fish‐kill resulted. All of these occurrences are related to the artificial circulation of the lake.
VALUING URBAN WATER ACQUISITIONS1
Authors: Griffin Ronald C.
Published: June 2007

ABSTRACT: Municipalities typically seek additional water supplies whenever prospective population and economic growth suggests the inadequacy of currently available water supply. The benefit of supply enhancement is usually construed as avoiding debilitating water scarcity. A more effective approach to planning is to compare the benefits and costs of supply augmentation. The net present value of benefits for a supply increase in a representative Texas community is calculated for alternative scenarios relating to population growth, rate growth, and the temporal distribution of the increased supply. Consumer surplus measures are sensitive to all three of these factors and vary from $0 to over $4000 per acre‐foot. A notable finding is that the added supply may offer zero values in cases where real water prices increase at an annualized rate of 4 percent (or greater) which is half the rate occurring in Texas from 1981–1985.
AQUIFER PARAMETERS FROM CONSTANT DRAWDOWN NONSTEADY‐LEAKY TYPE CURVES1
Authors: Motz Louis H.
Published: June 2007

ABSTRACT: A drain function and set of type curves were defined for the mathematical solution that represents one‐dimensional flow under nonsteady conditions in a leaky aquifer for the constant drawdown boundary condition. A match point procedure was developed for determining the aquifer parameters transmissivity, storage coefficient, and leakance based on the drain function and type curves. Use of the procedure is illustrated by an example that utilizes simulated aquifer drawdowns and flowrate data. The drain function and type curves developed in this investigation include the effects of leakage for the constant drawdown boundary condition, which is not included in the existing drain function and type curve found in the literature. Thus, a new set of type curves was developed that can be used to analyze drawdowns for one‐dimensional flow in a leaky aquifer with constant drawdown at a line sink. Applications would include flow to a canal or river, drainage of agricultural lands, and dewatering associated with strip mining operations.
CHANGING RAINFALL‐RUNOFF RELATIONSHIPS IN THE URBANIZING PEACHTREE CREEK WATERSHED, ATLANTA, GEORGIA1
Authors: Ferguson Bruce K , Suckling Philip W.
Published: June 2007

ABSTRACT: Peachtree Creek is a gaged watershed that has experienced a substantial increase in urbanization. The relationships of runoff to rainfall were studied for total annual flows, low flows, and peak flows. For each type of flow the relationship in the later, more urbanized period was compared to that in the earlier, less urbanized period. An increase in total runoff in wet years was observed as urbanization increased, but a decrease occurred during dry years. For low flows a similar decrease of runoff in dry years was found. An increase in peak runoff was observed over most of the range of precipitation. Increasing peak flows and declining low flows can be adequately explained by urban hydrologic theoryshed. which focuses on the effects of urban impervious surfaces upon direct runoff and infiltration. However, a decline of total runoff in dry years can be explained only by taking into account evapotranspiration as well. The concept of advectively assisted urban evapotranspiration, previously discovered by climatologists, is needed to explain such a loss of total runoff. Urban hydrologic theory must take into account vegetation and evapotranspiration, as well as impervious surfaces and their direct runoff, to explain the magnitude of total annual flows and low flows. Urban stormwater management should address the restoration of low flows, as well as the control of floods.
A SATURATION‐BASED MODEL OF RELATIVE WETNESS FOR WETLAND IDENTIFICATION1
Authors: Phillips Jonathan D.
Published: June 2007

ABSTRACT: A wetness index that was derived from Beven's distributed hillslope runoff model and based on the concept of relative wetness is introduced as a wetland identification and mapping tool. Data requirements are modified to make the model suitable for use by managers and field agents. The model predicts the relative propensity of any point or small area within a landscape unit to become saturated. This allows an index of relative wetness to be produced. Points on the landscape can then be assigned values of relative wetness. The index has potential utility for: (1) providing more detailed information on wetness conditions than binary (wetland‐nonwetland) classification systems now in use; (2) assisting in wetland identification when field indicators are absent or ambiguous; (3) application in dryland environments where common wetland indicators are largely irrelevant; and (4) broad‐scale wetland mapping in a geographic information systems environment using existing digital topographic and soils databases.
GROUND WATER FLOW AND RUNOFF IN A COASTAL PLAIN STREAM1
Authors: Williams John B. , Pinder John E.
Published: June 2007

ABSTRACT: The quantity, seasonality, and sources of flow were analyzed for two segments of Four Mile Branch, a small stream on the Coastal Plain of South Carolina using data obtained from USGS gauging stations. Flows in the “upstream segment,” a 12.6‐km2 watershed comprising the head waters of Four Mile Branch, averaged 0.129 m3 s−1 and showed a distinctly seasonal pattern, with maximum flows in February and March and minimum flows in September and October. Inflow to the “downstream segment,” a 2.2‐km2 watershed associated with the main channel, averaged 0.059 m3 s−1 and showed no seasonal patterns. Discharges per unit area of watershed were greater for the downstream segment, 0.83 m3 per year per m2 of land surface, than for the upstream segment, 0.32 m3 per year per m2. The differences in discharge rates and seasonalities between the two segments reflect differences in aquifers supplying the different segments. Analyses of Streamflow by hydrograph separation and Streamflow partitioning methods indicated that greater than 90 percent of the flows in the upstream and downstream segments were due to ground water‐driven base flows.
A HYDROCLIMATIC APPLICATION STRATEGY FOR THE POISSON PARTIAL DURATION MODEL1
Authors: Cruise J. F. , Arora K
Published: June 2007

ABSTRACT: A strategy for formulating and testing the Poisson partial duration extreme value model is presented. The procedure is demonstrated using recorded Streamflow series from a humid subtropical region of the southern United States. The observed data series are partitioned by climatic causes and tested for both the Poisson assumption and the validity of the exponential as marginal distributions. Several statistical tests are utilized in making these determinations. Some important aspects of the model as applied to humid climates are demonstrated. It was found that a majority of Streamflow series could be represented by the model and that significant differences do exist between the arrival structures of floods resulting from different climatic mechanisms. However, these differences generally do not exist in the distribution of the flood magnitudes. In addition, it is possible that model validity is restricted by drainage basin size.
MEASURING ECONOMIC LOSSES FROM GROUND WATER CONTAMINATION: AN INVESTIGATION OF HOUSEHOLD AVOIDANCE COSTS1
Authors: Abdalla Charles W.
Published: June 2007

ABSTRACT: Economic losses from ground water contamination were estimated in a central Pennsylvania community. The averting expenditures method was applied via a mail survey of households in which water contained the unregulated volatile organic chemical, perchloroethylene (PCE). Expenditures were estimated at $148,900 (1987 dollars) over the six‐month contamination period or approximately $252 per household annually. These costs underestimate the lower bound measure of welfare losses to households from ground water contamination. An upper bound measure of welfare losses was estimated at $383 per household annually. These estimates do not represent the full economic losses resulting from ground water contamination since the study did not address municipal‐level and business avoidance costs and losses from actual health effects, increased fear and anxiety, ecological damages, and nonuser ground water benefits. The results expand the existing empirical base of information about municipal‐level responses and economic losses from ground water contamination to include household‐level impacts. The findings indicate that households undertake substantial averting actions in response to ground water contamination and that such actions can have significant economic consequences. The extent and magnitude of avoidance costs documented suggests that policy‐makers should give greater attention to this category of economic losses.
DYNAMICS OF SIMULATED EFFECTS OF IRRIGATION OVER DRYLAND FARMING IN SASKATCHEWAN1
Authors: Schoney R. A. , Brown W. J. , Kulshreshtha S. N.
Published: June 2007

ABSTRACT: Irrigation development in Saskatchewan was initiated as an instrument to bring forth regional stability through drought proofing and diversification in the agricultural sector. This development has been surrounded by controversies. Particularly, some critics questioning its economic value to the farmer. In this study, irrigation on a farm is compared as a growth alternative to the expansion of dryland farming. Under relatively conservative machine replacement policies, modest family withdrawals, government subsidized irrigation loans, and relatively favorable gross operating margins, irrigation can be a profitable undertaking in the South Saskatchewan River Basin.
ESTIMATED RUNOFF FROM MAN‐MADE SNOW1
Authors: Eisel Leo M. , Bradley Kimberly M. , Leaf Charles F
Published: June 2007

ABSTRACT: The consumptive loss from man‐made snowmaking at six Colorado ski areas is calculated. The focus of the procedures in this investigation is on the consumptive loss that occurs to man‐made snow particles during the period they reside on or in the snowpack until spring snowmelt (termed the watershed loss). Calculated watershed losses under a variety of precipitation and temperature conditions at six ski areas varied from 7 to 33 percent. These calculations were made using the calibrated Subalpine Water Balance Simulation Model (Leaf and Brink, 1973a, 1973b). The watershed loss of 7 to 33 percent indicates the range of likely watershed losses that can be expected at Colorado ski areas.

A previous paper by the authors (Eisel et al., 1988) provided estimates of the mean consumptive loss during the snowmaking process (termed initial loss) for conditions existing at Colorado ski areas to be 6 percent of water applied. Therefore, based on the mean initial loss, the total consumptive loss from man‐made snowmaking under conditions found at Colorado ski areas could be expected to range from 13 to 37 percent. These results demonstrate the range of total consumptive losses that could be expected in various years and for various watershed conditions. These total percentage losses cannot be extrapolated directly to other specific sites because the total consumptive loss is dependent on temperature during actual snowmaking, temperature and precipitation throughout the winter at the specific ski area, and watershed conditions at the ski area. Consumptive losses to man‐made snow for a specific ski area should be estimated using the handbook procedures developed especially for this purpose (Colorado Ski Country USA, 1986b).
EFFECTS OF CLIMATIC CHANGE ON THE THORNTHWAITE MOISTURE INDEX1
Authors: McCabe Gregory J. , Wolock David M. , Hay Lauren E. , Ayers Mark A.
Published: June 2007

ABSTRACT: The Thornthwaite moisture index is a useful indicator of the supply of water (precipitation) in an area relative to the demand for water under prevailing climatic conditions (potential evapotranspiration). This study examines the effects of changes in climate (temperature and precipitation) on the Thornthwaite moisture index in the conterminous United States. Estimates of changes in mean annual temperature and precipitation for doubled‐atmospheric CO2 conditions derived from three general circulation models (GCMs) are used to study the response of the moisture index under steady‐state doubled‐CO2 conditions. Results indicate that temperature and precipitation changes under doubled‐CO2 conditions generally will cause the Thornthwaite moisture index to decrease, implying a drier climate for most of the United States. The pattern of expected decrease is consistent among the three GCMs, although the amount of decrease depends on which GCM climatic‐change scenario is used. Results also suggest that changes in the moisture index are related mainly to changes in the mean annual potential evapotranspiration as a result of changes in the mean annual temperature, rather than to changes in the mean annual precipitation.
IDENTIFYING AND MEASURING POTENTIAL CONFLICT IN WATER INSTITUTIONS1
Authors: Lynne Gary D. , Milon J. Walter , Wilson Michael E.
Published: June 2007

ABSTRACT: Scarcity combined with differences in values, beliefs, and attitudes can lead to behavior differences and conflicts over water. This paper develops an index for measuring potential conflict using survey information about water attitudes and beliefs of individuals in three groups in a Florida case study. The index helps in assessing the current capability of the institution to reduce conflict. The results suggest that the current institution is effective, but changes may help to streamline the consumptive‐use permitting process, to improve educational programs, and to seek improved institutional arrangements to reduce future conflict over economic uses of water.
NEW ZEALAND'S NATIONAL WATER QUALITY MONITORING NETWORK ‐ DESIGN AND FIRST YEAR'S OPERATION1
Authors: Smith D. G. , McBride G. B.
Published: June 2007

ABSTRACT: The design and implementation of a national surface water quality monitoring network for New Zealand are described. Some of the lessons learned from the first year of operation are also addressed. Underpinning the design, and specified in advance, are the goal and objectives, the data quality assurance system, and the mechanism for data interpretation and reporting. Because of the difficulties associated with the use of a multitude of different agencies, only one agency is involved in field work and one laboratory undertakes the analysis. Staff training has been given a high priority. The network has been designed to give good trend detectability for regular sampling over a 5–10 year period.
MACROPHYTE STANDING CROP AND PRIMARY PRODUCTWITY IN SOME FLORIDA SPRING‐RUNS1
Authors: Duarte Carlos M. , Canfield Daniel E.
Published: June 2007

ABSTRACT: A survey of 31 Florida spring‐runs was conducted to estimate their submerged macrophyte standing crop and primary productivity. The standing crops of submerged vegetation were not significantly (p > 0.05) correlated to either total nitrogen (r = 0) or total phosphorus (r =−0.20) concentrations, but standing crops were significantly (p < 0.01) correlated to the percentage of the spring‐run's water surface shaded by marginal vegetation (r =−0.76). Maximum daily rates of primary productivity were positively correlated with average submerged macrophyte standing crops (r = 0.81; p < 0.001) and inversely correlated with the degree of shading by marginal vegetation (r =− 0.43; p < 0.05).
THE POTENTIAL EFFECTS OF GLOBAL WARMING ON THE PRIMARY PRODUCTIVITY OF A SUBALPINE LAKE1
Authors: Byron Earl R. , Goldman Charles R.
Published: June 2007

ABSTRACT Atmospheric scientists have predicted that large‐scale climatic changes will result from increasing levels of tropospheric CO2 We have investigated the potential effects of climate change on the primary productivity of Castle Lake, a mountain lake in Northern California. Annual algal productivity was modeled empirically using 25 years of limnological data in order to establish predictive relationships between productivity and the climatic variables of accumulated snow depth and precipitation. The outputs of monthly temperature and precipitation from three general circulation models (GCMs) of doubled atmospheric CO2 were then used in the regression model to predict annual algal productivity. In all cases, the GCM scenarios predicted increased algal productivity for Castle Lake under cenditions of doubled atmospheric CO2The primary cause of enhanced productivity was the increased length of the growing season resulting from earlier spring ice‐out.
EVALUATION OF ALTERNATIVE CONFIGURATIONS OF BASIN ELEMENTS FOR ON‐LINE FLOOD FORECASTING1
Authors: Corradini Corrado
Published: June 2007

ABSTRACT: A simple adaptive model for on‐line flood forecasting in large basins is investigated. Alternative configurations of basin elements may be used in the model for the description of basin operation. Two basic versions of the model are considered. The first, denoted as model E, represents a basin as formed by an ensemble of ‘homogeneous’ elements and involves an adaptive estimate of parameters performed using only the discharge observed in real‐time at the outlet. The other, model D, is based on an additive adaptive estimate of parameters carried out upstream and considers a basin as a combination of a sub‐basin with an interbasin. However, each of these two large geometric elements is split up into smaller elements similar to those of model E. Each model version was tested for a lead time up to 6h by its application to events observed on large Italian basins. It was found that the performance of model E was invariant with basin area and main channel length and that model D was substantially better than model E. The latter conclusion has significant practical value for situations where an appropriate location for an additive flow measuring station can be established.
ATFITUDES TOWARDS ARTIFICIAL WETLANDS IN ONTARIO FOR STORMWATER CONTROL AND WATERFOWL HABITAT1
Authors: Carlisle Thomas , Mulamoottil George , Mitchell Bruce
Published: June 2007

ABSTRACT: The objective was to survey individuals from different interest groups in Ontario to ascertain attitudes towards the use of artificial wetlands for stormwater management and to provide waterfowl habitat. In total, 166 questionnaires were distributed and 124 cempleted returns were received. The results of the survey show that the provision of wetlands as waterfowl habitats in the context of stormwater impoundments is severely limited and is not considered an important management option. The overwhelming rejection of this integrated approach seems to be due to a lack of understanding and its comparative newness. Some of the perceived problems and concerns could be addressed by improvements in the design of the artificial wetlands. The design and implementation of an artificial wetland prototype as part of an education program in Ontario is recommended. A few research opportunities also are outlined.
MONITORING OPERATIONS PERFORMANCE IN LARGE‐SCALE PUBLIC IRRIGATION SYSTEMS IN INDONESIA1
Authors: Kelley Timothy G. , Johnson Sam H.
Published: June 2007

ABSTRACT: Different allocation and delivery performance ratios are used to assess operations performance in a large scale public irrigation system in Indonesia. Results from this analysis indicate that field management practices deviate substantially from the official operating procedures. The lack of application of a single, standardized procedure for planning water allocations represents a serious constraint to effective monitoring and evaluating system performance. Underestimated and unrealistic planned allocations becomes the justification for overdiversion of water, and has the effect of undermining the resolve of managers to see to it that actual flows meet planned flows.

Miscalculating planned allocations, poor matches between planned flows and actual deliveries, overdiversion and misreporting have economic consequences as well. For example, strict adherence to the standard operating rule during the second dry season of 1987 would have resulted in 19,070,000 m3 less water diverted into the irrigation system from the Brantas River or, at a conservative estimate of $1.78 per 100 m3 water, a savings of $339,500. Scope exists for making improvements in management by closer adherence to the standard delivery rule, which will also facilitate proper monitoring and evaluation.
PREDICTING MEASUREMENT ERROR OF AREAL MEAN PRECIPITATION DURING EXTREME EVENTS1
Authors: Fontaine Thomas A.
Published: June 2007

ABSTRACT: The areal mean precipitation (AMP) over a catchment is normally calculated using point measurements at rainfall gages. Error in AMP estimates occurs when an insufficient number of gages are used to sample precipitation which is highly variable in space. AMP error is investigated using historic, severe rainfalls with a set of hypothetical catchments and raingage networks. The potential magnitude of error is estimated for typical gage network densities and arrangements. Possible sources of error are evaluated, and a method is proposed for predicting the magnitude of error using data that are commonly available for severe, historic rainfall.
MOTIVATING REDUCTIONS IN DRAIN WATER WITH BLOCK‐RATE PRICES FOR IRRIGATION WATER1
Authors: Wichelns Dennis
Published: June 2007

ABSTRACT: Increasing block‐rate prices for irrigation water were implemented during 1989 in a 10,000‐acre irrigation district in California's San Joaquin Valley. The program motivated improvements in irrigation practices that reduced the volume of water delivered to farm fields and the volume of drain water collected in on‐farm drainage systems. The ratio of net crop water requirements to field deliveries increased from 0.65 in 1988 to 0.73 in 1989. The volume of drain water collected at a subset of 20 drainage systems was reduced by 351.1 acre‐feet (11.5 percent). Estimated loads of salt, boron, and selenium were reduced by 2,407 tons (11.0 percent), 3.33 tons (11.0 percent), and 0.07 tons (9.2 percent).
DETERMINANTS OF LANDOWNER'S WILLINGNESS TO PAY FOR FLOOD HAZARD REDUCTION1
Authors: Thunberg Eric , Shabman Leonard
Published: June 2007

ABSTRACT: Estimated benefits of flood control projects are typically limited to avoided property damages. However, the possibility that there are (1) benefits from reduced psychological stress among flood plain occupants, and (2) benefits to the community has long been recognized. A survey of landowners residing in a flood plain in Roanoke, Virginia, found that nonproperty considerations did help explain their expressed willingness to pay for flood control. Of particular importance was the respondents' concern for disruption of the community caused by possible flooding.
WATER REDUCTIONS FROM RESIDENTIAL AUDITS1
Authors: Whitcomb John B.
Published: June 2007

ABSTRACT: The water reductions resulting from Contra Costa Water District's 1989 residential audit program are measured using a multivariate regression model. The model explains metered residential water use as a function of both conservation and other household variables. The principle conclusions drawn are that (1) installation of low‐flow showerheads reduced indoor water use by 9.7 percent or 7.8 gallons per capita day, (2) the outdoor segment of the audit reduced irrigation needs by 18.7 percent, and (3) irrigation timers are being used inefficiently.
EVALUATION OF STORMSEWER CONTROL ALGORITHMS USING A TRANSIENT MIXED FLOW MODEL1
Authors: Cardle James A.
Published: June 2007

ABSTRACT: a hydraulic transient model that is capable of simultaneously modeling open channel and pressurized flows is used to study active control of a deep tunnel stormwater collection system. The simultaneous occurrence of open channel flow and pressurized flow is termed mixed flow. This paper demonstrates the application of a mixed flow hydraulic model to the development of an active control scheme. It is shown that dynamic conditions can exist in a storm sewer system even under moderate inflow conditions and that these conditions, particularly at the time of full system pressurization, can influence the operation of the dynamic control, so that accurate hydraulic modeling is essential to proper control formulation.
TRACE METALS IN SEDIMENT: SPATIAL TRENDS AND SORPTION PROCESSES1
Authors: Combest Kyle B.
Published: June 2007

ABSTRACT: Sediment bound trace metals are often examined for spatial trends such as downstream patterns or distance from a source. Spatial trends may indicate either differences in metal inputs, or, when considerable sediment variability exists, differences in sediment sorption processes. These two possibilities become important not only when sediment contamination is evaluated within an area, but also when regulatory agencies attempt to make equivalent among area decisions. Sediments from an urban watershed were examined for: (1) downstream trace metal trends and (2) sediment sorption relationships. Analyses determined that downstream trenda as related to metal inputs could not be recognized by analyzing the < 2mm (≤, sand) sediment size fraction. Conversely, the trace metal concentrations were found to be distinctly related to sediment characteristics. The watershed's metal concentrations are similar to those found in uncontaminated to slightly contaminated sediments in the United States.
WATER QUALITY TRENDS AT INFLOWS TO EVERGLADES NATIONAL PARK1
Authors: Walker William W.
Published: June 2007

ABSTRACT: Water quality data collected at inflows to Everglades National Park (ENP) are analyzed for trends using the seasonal Kendall test (Hirsch et al., 1982; Hirsch and Slack, 1984). The period of record is 1977–1989 for inflows to Shark River Slough and 1983–1989 for inflows to Taylor Slough and ENP's Coastal Basin. The analysis considers 20 water quality components, including nutrients, field measurements, inorganic species, and optical properties.

Significant (p<0.10) increasing trends in total phosphorus concentration are indicated at eight out of nine stations examined. When the data are adjusted to account for variations in antecedent rainfall and water surface elevation, increasing trends are indicated at seven out of nine stations. Phosphorus trend magnitudes range from 4 percent/year to 21 percent/year Decreasing trends in the Total N/P ratio are detected at seven out of nine stations. N/P trend magnitudes range from ‐7 percent/year to ‐15 percent/year. Trends in water quality components other than nutrients are observed less frequently and are of less importance from a water‐quality‐management perspective. The apparent nutrient trends are not explained by variations in marsh water elevation, antecedent rainfall, flow, or season.