bluuebunny/crossref_metadata_2025 huggingface dataset:
REHABILITATION OF WATERSHEDS WITH INCISING CHANNELS1
Authors: Shields F D. , Knight S.S. , Cooper C. M.
Published: June 2007

ABSTRACT: Channel incision is a pervasive problem that threatens infrastructure, destroys arable land, and degrades environmental resources. A program initiated in 1983 is developing technology for rehabilitation of watersheds with erosion and sedimentation problems caused by incision. Demonstration projects are located in 15 watersheds in the hills of northwest Mississippi. Watershed sizes range from 0.89 to 1,590 km2, and measured suspended sediment yields average about 1,100 t km‐2‐yr‐1. Water quality is generally adequate to support aquatic organisms, but physical habitat conditions are poor. Rehabilitation measures, which are selected and laid out using a subjective integration of hydraulic and geotechnical stability analyses, include grade controls, bank protection, and small reservoirs. Aquatic habitat studies indicate that stone‐protected stilling basins below grade‐control weirs and habitats associated with drop pipes and stone spur dikes are assets to erosion‐damaged streams. Additional recovery of habitat resources using modified stone stabilization designs, woody vegetation plantings, and reservoir outlets designed to provide non‐zero minimum flows is under investigation.
COMPARISON OF BANK EROSION AT VEGETATED AND NON‐VEGETATED CHANNEL BENDS1
Authors: Beeson C.E. , Doyle P. F.
Published: June 2007

ABSTRACT: Following major floods in 1990 which resulted in widespread bank erosion in southern British Columbia, four streams typical of the region were evaluated for the effect which riparian vegetation played in reducing erosion. A total of 748 bends in the four stream reaches were assessed by comparing pre‐ and post‐flood aerial photography. Bends without riparian vegetation were found to be nearly five times as likely as vegetated bends to have undergone detectable erosion during the flood events. Major bank erosion was 30 times more prevalent on non‐vegetated bends as on vegetated bends. The likelihood of erosion on semi‐vegetated bends was between that of the vegetated and non‐vegetated categories of bends.
A VOLUME BALANCE SOLUTION FOR WATER FLOW OVER FLAT SOIL SURFACES1
Authors: Guardo Mariano
Published: June 2007

ABSTRACT: This paper presents the development of a mathematical model to compute the advance of water flowing over flat soil surfaces. The solution is of interest to the design and management of irrigation systems, and the model can also be applied to overland flow problems. The hydraulics of water flow during the advance phase is simulated by the Lewis‐Milne integral equation. The general solution to this equation is obtained by using the Laplace transform theory. A particular solution was developed, based on series expansions, that uses the modified Kostiakov equation to predict infiltration. The solution is given by a double infinite series that has terms of alternate sign. Results from this model show satisfactory agreement when compared with field data collected by the author.
THE LEVEE LOVE AFFAIR: A STORMY RELATIONSHIP?1
Authors: Tobin Graham A.
Published: June 2007

ABSTRACT: A history of flood control in the United States shows an undying affair with levees. This love affair, however, was put severely to the test by the record flooding in the summer of 1993. About 70 percent of levees in the upper Midwest failed during this time, leading to extensive damage to both farmland and urban areas. Consequently, there were repeated calls to re‐assess the nation's floodplain management policies. The report of the Intera‐gency Floodplain Management Review Committee is one outcome of this and it forms the basis of this commentary on levees. In many respects, levees are effective flood control measures, being relatively cheap to implement and easy to build. At the same time, levees have negative impacts, affecting the hydrological regime both up and down stream, and often exacerbating flooding in other places. Furthermore, technical weaknesses in design, planning, construction, and maintenance have all contributed to levee failures. While the report recommends changes in floodplain management to address some of these issues, it is difficult to see how these will materialize given the current political, economic, and social climate.
REGIONAL ASSESSMENT OF NLEAP NO3‐N LEACHING INDICES1
Authors: Wylie B. K. , Shaffer M. J. , Hall M. D.
Published: June 2007

ABSTRACT: Nonpoint source ground water contamination by nitrate nitrogen (NO3‐N) leached from agricultural lands can be substantial and increase health risks to humans and animals. Accurate and rapid methods are needed to identify and map localities that have a high potential for contamination of shallow aquifers with NO3‐N leached from agriculture. Evaluation of Nitrate Leaching and Economic Analysis Package (NLEAP) indices and input variables across an irrigated agricultural area on an alluvial aquifer in Colorado indicated that all leaching indices tested were more strongly correlated with aquifer NO3‐N concentration than with aquifer N mass. Of the indices and variables tested, the NO3‐N Leached (NL) index was the NLEAP index most strongly associated with groundwater NO3‐N concentration (r2 values from 0.37 to 0.39). NO3‐N concentration of the leachate was less well correlated with ground water NO3‐N concentration (r2 values from 0.21 to 0.22). Stepwise regression analysis indicated that, although inorganic and organic/inorganic fertilizer scenarios had similar r2 values, the Feedlot Indicator (proximity) variable was significant over and above the NO3‐N Leached index for the inorganic scenario. The analysis also showed that combination of either Movement Risk Index (MIRI) or NO3‐N concentration of the leachate with the NO3‐N Leached index leads to an improved regression, which provides insight into area‐wide associations between agricultural activities and ground water NO3‐N concentration.
BSENEFICIAL USE POTENTIAL OF DRY WEATHER FLOW IN THE LAS VEGAS VALLEY, NEVADA1
Authors: Mizell Steve A. , French Richard H.
Published: June 2007

ABSTRACT: Historically ephemeral washes in the Las Vegas Valley have become perennial streams in the urbanized area, and the primary source of these perennial flows appears to be the overirrigation of ornamental landscaping and turf. Overirrigation produces direct runoff to the washes via the streets and results in high ground water levels in some areas. Elevated ground water levels result in discharge to the washes because of changes in the natural balance of the hydrologic system and construction site and foundation dewatering. In recognition of the resource potential of these flows within the Las Vegas Valley, of the potential for dry weather flows to convey pollutants from the Valley to Lake Mead, and of the need to characterize dry weather flows under the stormwater discharge permit program, the quantity and quality of dry weather flow in Flamingo Wash was investigated during the period September 1990 through May 1993. This paper focuses on the resource potential of the flow (quantity and quality) as it relates to the interception and use of this water within the Valley. Economic and legal issues associated with the interception and use of this resource are not considered here.
HEAVY RAINFALL DISTRIBUTIONS BY SEASON IN LOUISIANA: SYNOPTIC INTERPRETATIONS AND QUANTILE ESTIMATES1
Authors: Keim Barry D. , Faiers Gregory E.
Published: June 2007

ABSTRACT: In most studies, quantile estimates of extreme 24‐hour rainfall are given in annual probabilities. The probability of experiencing an excessive storm event, however, differs throughout the year. As a result, this paper explored the differences between heavy rainfall distributions by season in Louisiana. It was concluded by using the Kruskal‐Wallis and Mann‐Whitney tests that the distribution of heavy rainfall events differs significantly between particular seasons at the sites near the Gulf Coast. Furthermore, seasonal frequency curves varied dramatically at the four sites examined. Mixed distributions within these data were not found to be problematic, but the mechanisms that produced the events were found to change seasonally. Extreme heavy rainfall events in winter and spring were primarily generated by frontal weather systems, while summer and fall events had high proportions of events produced by tropical disturbances and airmass (free‐convective) conditions.
REGION OF INFLUENCE REGRESSION FOR ESTIMATING THE 50‐YEAR FLOOD AT UNGAGED SITES1
Authors: Tasker Gary D. , Hodge Scott A. , Barks C. Shane.
Published: June 2007

ABSTRACT: Five methods of developing regional regression models to estimate flood characteristics at ungaged sites in Arkansas are examined. The methods differ in the manner in which the State is divided into subregions. Each successive method (A to E) is computationally more complex than the previous method. Method A makes no subdivision. Methods B and C define two and four geographic subregions, respectively. Method D uses cluster/discriminant analysis to define subregions on the basis of similarities in watershed characteristics. Method E, the new region of influence method, defines a unique subregion for each ungaged site. Split‐sample results indicate that, in terms of root‐mean‐square error, method E (38 percent error) is best. Methods C and D (42 and 41 percent error) were in a virtual tie for second, and methods B (44 percent error) and A (49 percent error) were fourth and fifth best.
A COMPARISON OF HAND‐ AND SPLINE‐DRAWN PRECIPITATION MAPS FOR MOUNTAINOUS MONTANA1
Authors: Custer Stephan G. , Fames Phillip , Wilson John P , Snyder Robert D.
Published: June 2007

ABSTRACT: Average annual precipitation for the period 1961–1990 was estimated for a mountainous region in Montana with a Laplacian thin‐plate spline (ANUSPLIN) and compared to a hand‐drawn map. Input data included latitude, longitude, and elevation from a three‐arc‐second U.S. Geological Survey Digital Elevation Model of the Bozeman and Billings 1 × 2 topographic quadrangles and precipitation data at 96 stations. The two maps are similar in appearance. Digital comparison of the two maps with ARC/INFO's Grid tools shows that mean annual precipitation for the hand‐contoured map is 22.9 inches and for the ANUSPLIN map is 23.7 inches. Of the 5,760,000 cells, 53 percent showed no difference between ANUSPLIN and hand‐drawn maps; 19 percent showed a two‐inch difference, and 28 percent showed more than 2 inches difference. Input data and model output at the same location are not different (standard deviation 1.77, p‐value 0.76). Hand‐drawn maps show two inches more precipitation during the 1961–90 period than during the 1941–1970 period. Similarly, measured data at 73 sites for the period 1961–1990 are on average 2.4 inches higher than the same stations during the 1941–1970 period. The difference is significant (p‐value > 0.0001).
EQUILIBRIUM AND TRANSIENT GLOBAL WARMING SCENARIO IMPLICATIONS FOR WATER RESOURCES IN WALES1
Authors: Holt C. P. , Jones J. A. A.
Published: June 2007

ABSTRACT: A methodology has been developed to predict the responses of a range of water supply sources in Wales to global warming scenarios. Hydrologically effective rainfall is predicted from temperature and precipitation for each season based on site specific formulae developed using the Meteorological Office Rainfall and Evaporation Calculation System (MORECS) and UK Surface Water Archive databases. Comparisons are then made between the effects predicted for the scenarios established from equilibrium simulations and the new Hadley Centre High Resolution Model (UKHI) transient mode results. Though very different, both suggest increased stress on water resources late in the hydrological year.
STREAMFLOW TRENDS IN WISCONSIN'S DRIFTLESS AREA1
Authors: Gebert Warren A. , Krug William R.
Published: June 2007

ABSTRACT: Trends in streamflow characteristics were analyzed for streams in southwestern Wisconsin's Driftless Area by using data at selected gaging stations. The analyses indicate that annual low flows have increased significantly, whereas annual flood peaks have decreased. The same trends were not observed for forested areas of northern Wisconsin. Streamflow trends for other streams in southeastern Wisconsin draining predominantly agricultural land were similar to trends for Driftless Area streams for annual low flows. The causes for the trends are not well understood nor are the effects. Trends in annual precipitation do not explain the observed trends in streamflow. Other studies have found that erosion rates decreased significantly in the Driftless Area, and have attributed this reduction to a change of agricultural practices, which increase infiltration, decrease flood peaks, and increase low flows.
HYDROLOGIC LANDSCAPES ON THE DELMARVA PENINSULA PART 2: ESTIMATES OF BASE‐FLOW NITROGEN LOAD TO CHESAPEAKE BAY1
Authors: Bachman L. Joseph. , Phillips Patrick J.
Published: June 2007

ABSTRACT: Base‐flow samples were collected from 47 sampling sites for four seasons from 1990–91 on the Delmarva Peninsula in Delaware and Maryland to relate stream chemistry to a “hydrologic landscape” and season. Two hydrologic landscapes were determined: (1) a well‐drained landscape, characterized by a combination of a low percentage of forest cover, a low percentage of poorly drained soil, and elevated channel slope; and (2) poorly drained landscape, characterized by a combination of an elevated percentage of forest cover, an elevated percentage of poorly drained soil, and low channel slope. Concentrations of nitrogen were significantly related to the hydrologic landscape. Nitrogen concentrations tended to be higher in well‐drained landscapes than in poorly drained ones. The highest instantaneous nitrogen yields occurred in well‐drained landscapes during the winter. These yields were extrapolated over the part of the study area draining to Chesapeake Bay in order to provide a rough estimate of nitrogen load from base flow to the Bay and its estuarine tributaries. This estimate was compared to an estimate made by extrapolating from an existing long‐term monitoring station. The load estimate from the stream survey data was 5 ± 106 kg of N per year, which was about four times the estimate, made from the existing long‐term monitoring station. The stream‐survey estimate of base flow represents about 40 percent of the total nitrogen load that enters the Bay and estuarine tributaries from all sources in the study area.
WATER QUALITY STRATIFICATION IN SHALLOW WASTEWATER STABILIZATION PONDS1
Authors: Gu Ruochuan , Luck Frederick N. , Stefan Heinz G.
Published: June 2007

ABSTRACT: The physical limnology of three modern wastewater stabilization ponds serving a small community in Minnesota was investigated over a 1‐year period (July 1989 ‐ October 1990). Water temperatures and associated meteorological parameters were recorded continuously; underwater light, dissolved oxygen, pH, and Secchi depth were measured intermittently (about weekly). Measurements of nutrients and planktonic species were made by other investigators. Water quality stratification dynamics were studied by analyzing variations of water temperature, dissolved oxygen, and pH distributions with time and over depth. Intermittent stratification and mixing of the shallow waste stabilization ponds (1–2 m deep) were documented and related to weather. The strong response of the ponds to seasonal and daily weather variations was observed. Three types of pond stratification conditions have been identified: (1) completely mixed during consecutive day and night, (2) stratified during the day and well‐mixed during the night, and (3) continuously stratified during day and night. A diurnal cycle of stratification dynamics was first noticed in late April and persisted through summer and into fall. Differences in light attenuation and hence temperature stratification and DO distribution between pond 1 (primary), pond 2 (second primary) and pond 3 (secondary) in the wastewater treatment system were documented and related to different waste loading conditions. Temperature stratification affects chemical, microbial, and planktonic processes in the ponds. Results presented in this paper can be used to provide guidance for water quality sampling in monitoring of pond performance. Information on true mixing conditions is also needed to gain better understanding of important factors affecting pond operation, and for process simulations and reactor modeling of waste stabilization ponds.
DRAINAGE GENERATION AND WATER USE IN THE EVERGLADES AGRICULTURAL AREA BASIN1
Authors: Abtew W. , Obeysekera J.
Published: June 2007

ABSTRACT: The Everglades Agricultural Area (EAA) covers 2,850 km2 in area and is characterized by high water table and organic soil. The area is actively irrigated and drained as a function of weather conditions and crop status. Anthropogenic activities in the basin have resulted in nutrient‐enriched drainage water that is discharged to Lake Okeechobee and the Everglades ecosystem. Water quantity and quality issues of the basin have become of increasing interest at local, state, and federal levels, so legislative and regulatory measures have been taken to improve water quality in discharges from the basin. In this study, simulation of hydrologic conditions and soil moisture were conducted using 100 years of daily synthetic rainfall data. From the simulations, the statistical distribution of half‐month drainage discharge and supplemental water use in the basin was developed. The mean annual drainage/runoff was 49 cm, the mean supplemental water was 30 cm, and the mean annual a real rainfall was 122 cm. On the average, drainage exceeded supplemental water use in the months of June to September while from December to March drainage and supplemental water use were equivalent. Supplemental water use exceeded drainage in the months of October, November, April, and May. High drainage occurred in June and September; smallest drainage was in February. On the average, the highest supplemental water use occurred in May and November. The 10‐year return period of annual drainage during wet and dry cycles were 60 cm and 38 cm per year, respectively. The semi‐monthly drainage coefficient of variation (cv) is above 100 percent for the period from the second half of October to end of April. The cv is lower than 100 percent for the remaining season (wet season). The purpose of this paper is to present the magnitude, temporal, and frequency distribution of drainage runoff generation and supplemental water use in the EAA basin. Information on statistics of drainage will contribute to the optimization of the design and operation of drainage water treatment systems.
DISTRIBUTION OF NITRATE AND ORTHOPHOSPHATE IN SELECTED STREAMS IN CENTRAL NEBRASKA1
Authors: Boyd Robert A.
Published: June 2007

ABSTRACT: The Central Nebraska Basins is one of 60 study units in the National Water‐Quality Assessment Program of the U.S. Geological Survey. The study unit includes the Platte River and two major tributaries, the Loup and Elkhorn Rivers. Agriculture is the predominant land use in the study unit, with only eight urbanized communities exceeding a population of 10,000. Water samples were collected from selected streams in the study unit during 1993–1995. The data were used to assess the distribution of nitrogen compounds and phosphorus in the streams and to relate the concentrations of these constituents to environmental settings. This article focuses on dissolved nitrate and orthophosphate. Dissolved nitrate concentrations were highest (90th percentiles were less than 7.0 milligrams per liter as nitrogen) in areas with extensive cropland and pasture, where chemical fertilizers are intensively applied. Synoptic measurements conducted in March and August 1994 indicate that relatively little residual fertilizer, as nitrate, applied during a single crop‐growing season enters streams. Dissolved nitrate concentrations showed a seasonal pattern, being highest during winter months and lowest during the late spring and summer. Dissolved orthophosphate concentrations tended to be low across the study unit, 90 percent of all analyses did not exceed 1.7 milligrams per liter as phosphorus.
STATISTICAL LOW FLOW ESTIMATION USING GIS ANALYSIS IN HUMID MONTANE REGIONS IN PUERTO RICO1
Authors: Garcia‐Martinó Andres R. , Scatena Frederick N. , Warner Glenn S. , Civco Daniel L.
Published: June 2007

ABSTRACT: Statistical analysis of watershed parameters derived using a Geographical Information system (GIS) was done to develop equations for estimating the 7d–10yr, 30d–10yr, and 7d–2yr low flow for watersheds in humid montane regions of Puerto Rico. Digital elevation models and land use, geology, soils, and stream network coverages were used to evaluate 21 geomorphic, 10 stream channel, 9 relief, 7 geology, 4 climate, and 2 soil parameters for each watershed. To assess which parameters should be used for further investigation, a correlation analysis was used to determine the independence and collinearity among these parameters and their relationship with low flows. Multiple regression analyses using the selected parameters were then performed to develop the statistical models of low flows. The final models were selected in the basis of the Mallow Cp statistic, the adjusted R2, the Press statistic, the degree of collinearity, and an analysis of the residuals. In the final models, drainage density, the ratio of length of tributaries to the length of the main channel, the percent of drainage area with northeast aspect, and the average weighted slope of the drainage were the most significant parameters. The final models had adjusted standard errors of 58.7 percent, 59.2 percent, and 48.6 percent for the 7d–10yr, 30d–10yr, and 7d–2yr low flows respectively. For comparison, the best model based on watershed parameters that can be easily measured without a GIS had an adjusted standard error of 82.8 percent.
DIFFERENCES IN WARM‐SEASON, RAINSTORM‐GENERATED STORMFLOWS FOR NORTHEASTERN ILLINOIS URBANIZED BASINS1
Authors: Changnon David , Fox Doug , Bork Steve
Published: June 2007

ABSTRACT: Precipitation, streamflow, and population data were analyzed over the 1941–1990 period to determine whether changes in stormflows and net (post. minus pre‐rainstorm) stormflows, associated with warm‐season large rainstorms, were similar for two urbanized northeastern Illinois basins. Warm season large rainstorms were defined as April through October rainfall events in which ≪ 5.1 cm occurred in a 48‐hour period over the basin. To minimize differences associated with varying large rainstorm amounts over time, the net sthrmflow for each event was divided by the large rainstorm amount. This ratio, Ui, indicated that the two urbanized basins experienced significant, yet different, increases (102 percent and 49 percent) in flow amount per centimeter of rainfall from 1941–1965 to 1966–1990. Results of a regression analysis between Ui and population showed that the increase in Ui per 100,000 increase in population ranged from 0.59 to 0.67 m3s‐1 per cm of rainfall for the two basins. These results demonstrate the varying degree of change that urban planners can expect in stormflows associated with large warm season rainstorms for areas undergoing urbanization.
ANALYSIS AND EXTRACTION OF LOW FLOW RECESSION CHARACTERISTICS1
Authors: Sugiyama Hironobu
Published: June 2007

ABSTRACT: It is important to extract and assess low flow recession characteristics for water resources planning in the upper reaches of streams. However, it is very difficult to express synthetically the low flow recession characteristics for a stream flow. In this paper, first a new method of constructing the master recession curve based on the exponential expression is proposed and applied with the restriction that there are no regulation or diversion structures in the upper reaches above the measurement station. Daily precipitation and stream flow were used for the analysis. Second, analysis for a recession constant was conducted and the relationship between the recession constant and low flow and/or geology was qualitatively examined. In conclusion, the application of the proposed method indicated that it is objective and useful for constructing the master recession curve. It became apparent that the recession constant of a master recession curve may be defined as the total index of low flow characteristics. In addition, it was found that baseflow value increases in the order of Paleozoic, Mesozoic, Tertiary, and Quaternary.
EVALUATION OF URBAN STREAM CORRIDOR RESTORATION DESIGN ALTERNATIVES USING HEC‐21
Authors: Morris Scott
Published: June 2007

ABSTRACT: The rehabilitation of urban stream channels and riparian areas involves a potentially large number of design alternatives. When substantial modifications are planned, water surface profile models (e.g., HEC‐2) provide a means for a thorough and efficient evaluation of many design variations. The rehabilitation of a reach of Paradise Creek, Idaho, utilized the REC‐2 model to verify the appropriateness of a new channel geometry and explore the consequences of variable floodplain geometries and excavation depths. The desirability of habitat diversity, coupled with the constraints of minimized earthwork costs and adequate flow capacity, framed the floodplain design question. The final design geometry was iteratively approached using the HEC‐2 model to mimic the existing channel capacity. This modeling framework produces as output computed water surface elevations for the design channel and floodplain under any discharge. Hence, the method provides the means for demonstrating that rehabilitation designs will (or will not) cause increases in flood elevations, an assessment that is generally required for project approval.
IMPROVED ESTIMATION OF ECOLOGICAL EFFECTS USING AN EMPIRICAL BAYES METHOD1
Authors: Reckhow Kenneth H.
Published: June 2007

ABSTRACT:The US Environmental Protection Agency is currently developing guidance for assessing environmental impact using biocriteria within a regulatory framework. Of particular interest are statistical methods of design and analysis to test for impairment of biological assemblages in stream ecosystems associated with water pollution. Current recommendations emphasize frequentist statistical methods with the problem expressed as one of classical hypothesis testing. An empirical Bayes approach is proposed here as an alternative and applied for multi‐site inference. The advantages of an empirical Bayes approach, in particular the substantive contribution of collateral information from nearby sites, are discussed in contrast to traditional methods that employ site‐specific information only. The approach is illustrated in an application concerning trends in the Index of Biotic Integrity (IHI) for the Scioto River in Ohio.
COUNTY COMMISSIONERS' WATER KNOWLEDGE1
Authors: Berry Kate A. , Markee Nancy L. , Stewart Michael J. , Giewat Gary R.
Published: June 2007

ABSTRACT: This study examines the social construction of county commissioners' knowledge about water. Factors that influence what commissioners know about water include each commissioner's personal characteristics, education, experience in natural resources management, involvement in policy making, and use and evaluation of various sources of information. This study focused on county commissioners representing rural, mixed, and urban counties in Arizona, Nevada, and Utah and collected data through mail surveys and interviews.

County commissioners in the survey were well educated; however, few had taken college courses directly addressing technical, management, or legal aspects of water issues. Approximately one‐third had direct experience in farming and ranching; nearly two‐thirds indicated that farming and ranching played a major role in their communities. Respondents had experience with a broad range of water policy issues. In evaluating thirteen information sources in terms of their frequency of use, relevancy, and reliability, respondents assessed fellow commissioners and local government staff and managers most positively and nonprofit organizations most negatively. The media was also broadly rated as less relevant and reliable than other sources of information. The commissioners in the study expressed a high level of general concern about water issues and a strung preference for local sources of information.
STREAMFLOW MEASUREMENT USING SALT DILUTION IN TUNDRA STREAMS, NORTHWEST TERRITORIES, CANADA1
Authors: Spence Chris , McPhie Michael
Published: June 2007

ABSTRACT: With the recent increased exploration and mining activity in the Northwest Territories, there has been growing interest in streamflows. However, streamflow monitoring in Canada's north is limited, especially in the central Northwest Territories where the exploration activity is concentrated. To complicate matters, the standard approach of measuring discharge with current meters or weirs is often inadequate or prohibitively expensive, as many streams in the region are shallow, braided and rocky. In response, alternative techniques such as salt dilution can be used. A salt tracer's competence in turbulent and rocky channels makes it ideal for discharge measurements in these situations. This paper summarizes the work performed by Indian and Northern Affairs Canada and Canamera Geological Ltd. staff in determining the stream discharge of a lake outlet using a potassium chloride (KC1) tracer. A variety of streamflow measurement methods were performed and compared to determine the viability and rigor of the dilution method. Results suggest the dilution method compares favorably to other measurement techniques both in accuracy and operational ease.
WATERSHEDSS: A DECISION SUPPORT SYSTEM FOR WATERSHED‐SCALE NONPOINT SOURCE WATER QUALITY PROBLEMS1
Authors: Osmond D. L. , Cannon R. W. , Gale J. A. , Line D. E. , Knott C. B. , Phillips K A. , Thrner M. H. , Foster M. A. , Lehning D. E. , Coffey S. W. , Spooner J.
Published: June 2007

ABSTRACT: A significant portion of all pollutants entering surface waters (streams, lakes, estuaries, and wetlands) derives from non‐point source (NPS) pollution and, in particular, agricultural activities. The first step in restoring a water resource is to focus on the primary water quality problem in the watershed. The most appropriate NPS control measures, which include best management practices (BMPs) and landscape features, such as wetlands and riparian areas, can then be selected and positioned to minimize or mitigate the identified pollutant(s). A computer‐based decision sup. port and educational software system, WATERSHEDSS (WATER, Soil, and Hydro‐Environmental Decision Support System), has been developed to aid managers in defining their water quality problems and selecting appropriate NPS control measures. The three primary objectives of WATERSHEDSS are (1) to transfer water quality and land treatment information to watershed managers in order to assist them with appropriate land management/land treatment decisions; (2) to assess NPS pollution in a watershed based on user‐supplied information and decisions; and (3) to evaluate, through geographical information systems‐assisted modeling, the water quality effects of alternative land treatment scenarios. WATERSHEDSS is available on the World Wide Web (Web) at http://h2osparc.wq.ncsu.edu.
CHANGES IN WATER QUALITY IN THE NEWLY IMPOUNDED SUBTROPICAL FEITSUI RESERVOIR, TAIWAN1
Authors: Chang Shui‐Ping , Wen Ching‐Gung
Published: June 2007

ABSTRACT: Water quality and trophic conditions in the Feitsui Reservoir, a subtropical reservoir, were evaluated with data from a ten‐year data base to depict the impacts of river impoundment upon the chemical and biological characteristics of a reservoir, and to discuss the effects of flushing rate on in‐lake phosphorus concentrations and phytoplankton growth. The results of the investigation showed that during the incipient impounding period, the water quality in the Feitsui Reservoir was significantly affected by internal loadings from submerged vegetation and soil in the flooded area. Studies of the changes in phosphorus compounds indicated that total phosphorus concentration appeared to approach equilibrium after the seventh year of impoundment and that orthophosphate stabilized after the sixth year of impoundment. Concentrations of both phosphorus forms varied seasonally after attaining stability. Nitrogen compounds (NH3‐N, NO3‐N and NO2‐N) approached equilibrium within three years after impoundment. The seasonal variation in carbon was correlated to the number of phytoplankton. The mean value of the N:P mass ratio has remained over 110 since year seven of impoundment (1990), indicating that phosphorus constitutes the potential limiting nutrient in the growth of phytoplankton. The rapid flushing rate (132.11 and 110.43 yr‐1) in Feitsui Reservoir during the first and second impounding stages was a critical factor influencing the phytoplankton growth response to available nutrients.
FARM‐LEVEL MANAGEMENT OF DEEP PERCOLATION EMISSIONS IN IRRIGATED AGRICULTURE1
Authors: Posnikoff Judith F , Knapp Keith C.
Published: June 2007

ABSTRACT: Source control costs for deep percolation emissions from irrigated agriculture are analyzed using a farm‐level model. Crop area, irrigation system and applied water are chosen to maximize the net benefits of agricultural production while accounting for the environmental damages and disposal costs of those emissions. Deep percolation is progressively reduced as environmental and disposal costs are increased. This occurs primarily through the adoption of more efficient irrigation technology and reductions in applied water for a given technology Higher surface water prices, such as through irrigation reform and constrained surface supplies, are additionally considered in light of the drainage problem, as are the effects, both short‐ and long‐term, on ground water use.
PRESENCE AND DISTRIBUTION OF TRACE ELEMENTS IN NEW JERSEY STREAMBED SEDIMENTS1
Authors: O'Brien Anne K
Published: June 2007

ABSTRACT: The distribution of trace elements in New Jersey streambed sediments is described with respect to physiographic provinces and major drainage areas. Samples were collected during 1976–1993 at 295 sites distributed throughout New Jersey. Copper, chromium, lead, and zinc were detected with the greatest frequency and at the highest concentrations of the elements. Concentrations of most trace elements were significantly higher in streambed sediments from the New England (glaciated) and Piedmont physiographic provinces ‐ the provinces with the lowest and highest percentages of urban land use, respectively ‐ than in sediments from the other provinces. High trace‐element concentrations in the New England (glaciated) province reflect previous mining of extensive magnetite deposits, whereas those in the Piedmont province most likely reflect urban land use. Significantly lower trace‐element concentrations in streambed sediments from the Coastal Plain are attributable to the low pH of the streamwater, the lack of iron and manganese available to form coatings that scavenge trace elements, and the relatively low percentage of urban land use in the province. Trace‐element concentrations were related to land use, population, or point sources in the drainage basin specific to the sampling location by using logistic regression. Results of this analysis indicate a relation between arsenic and agricultural land use; chromium and physiographic province; and copper, lead, and zinc and population density.
NUTRIENT MASS BALANCE FOR THE ALBEMARLE‐PAMLICO DRAINAGE BASIN, NORTH CAROLINA AND VIRGINIA, 19901
Authors: McMahon Gerard , Woodside Michael D.
Published: June 2007

ABSTRACT: A 1990 nitrogen and phosphorus mass balance calculated for eight National Stream Quality Accounting Network (NASQAN) basins in the Albemarle‐Pamlico Drainage Basin indicated the importance of agricultural nonpoint sources of nitrogen and phosphorus and watershed nitrogen retention and processing capabilities. Basin total nitrogen and phosphorus input estimates were calculated for atmospheric deposition (which averaged 27 percent of total nitrogen inputs and 22 percent of total phosphorus inputs); crop fertilizer (27 and 25 percent); animal‐waste (22 and 50 percent, respectively); point sources (3 percent each of total nitrogen and total phosphorus inputs); and biological nitrogen fixation (21 percent of total nitrogen inputs). Highest in‐stream nitrogen and phosphorus loads were measured in predominantly agricultural drainage areas. Intermediate loads were observed in mixed agricultural/urban drainage areas; the lowest loads were measured in mixed agricultural/forested drainage areas. The difference between the sum of the nutrient input categories and the sum of the in‐stream nutrient loads and crop‐harvest nutrient removal was assigned to a residual category for the basin. The residual category averaged 51 percent of total nitrogen inputs and 54 percent of total phosphorus inputs.
AN INTERACTWE MODELING ENVIRONMENT FOR NON‐POINT SOURCE POLLUTION CONTROL1
Authors: Liao Hsiu‐Hua , Tim U.S.
Published: June 2007

ABSTRACT: Non‐point source pollution cuntinues to be an important environmental and water quality management problem. For the moat part, analysis of non‐point source pollution in watersheds has depended on the use of distributed models to identify potential problem areas and to assess the effectiveness of alternative management practices. To effectively use these models for watershed water quality management, users depend on integrated geographic information systems (GIS)‐based interfaces for input/output data management. However, existing interfaces are ad‐hoc and the utility of GIS is limited to organization of input data and display of output data. A highly interactive water quality modeling interface that utilizes the functional components and analytical capability of GIS is highly desirable. This paper describes the tight coupling of the Agricultural Non‐point Source (AGNPS) water quality model and ARC/INFO GIS software to provide an interactive hybrid modeling environment for evaluation of non‐point source pollution in a watershed. The modeling environment is designed to generate AGNPS input parameters from user‐specified GIS coverages, create AGNPS input data files, control AGNPS model simulations, and extract and organize AGNPS model output data for display. An example application involving the estimation of pesticide loading in a southern Iowa agricultural watershed demonstrates the capability of the modeling environment. Compared with traditional methods of watershed water quality modeling using the AGNPS model or other ad‐hoc interfaces between a distributed model and GIS, the interactive modeling environment system is efficient and significantly reduces the task of watershed analysis using tightly coupled GIS databases and distributed models.
PRECISION OF CHANNEL WIDTH AND POOL AREA MEASUREMENTS1
Authors: Myers Thomas J. , Swanson Sherman
Published: June 2007

ABSTRACT: The precision of width and pool area measurements has rarely been considered in relation to downstream or at section hydraulic geometry, fisheries studies, long‐term or along a continuum research studies, or agency monitoring techniques. We assessed this precision and related it to other stream morphologic characteristics. Confidence limits (95 percent) around mean estimates with four transects (cross‐sections perpendicular to the channel center‐line) ranged from ± 0.4 to 1.8 m on streams with a width of only 2.2 m. To avoid autocorrelation, transects should be spaced about three channel widths apart. To avoid stochastic inhomogeneity, reach length should be about 30 channel widths or ten transects to optimize sampling efficiency. Precision of width measurements decreased with decreased depth and increased with stream size. Both observations reflect variability caused by features such as boulders or coarse woody debris. Pool area precision increased with pool area reflecting increased precision for flat, wide streams with regular pool‐rime sequences. The least precision occurred on small, steep streams with random, boulder or coarse woody debris formed pools.
VEGETATION INFLUENCE ON SMALL STREAM SILTATION1
Authors: Thornton Christopher I. , Abt Steven R. , Clary Warren P.
Published: June 2007

ABSTRACT: A meandering stream channel was simulated in the Hydraulics Laboratory at Colorado State University and a series of tests was conducted using four types of vegetation to evaluate the potential effects of vegetation on sediment deposition and retention in a stream channel. The data collected included average flow velocity, flow depth, length of vegetation, density of vegetation, cross‐sectional area of the vegetative stem, wetted perimeter of the vegetative stem, and injection and flushing time. The findings indicated that the vegetation could retain from 30 to 70 percent of the deposited sediments. The ability of vegetation to entrap and retain sediment is related to the length and cross‐sectional area of the vegetation. The variables describing the flow and the vegetative properties were combined to form a predictive parameter, the sedimentation factor (Sd) that can be compared with the amount of sediment entrapped by vegetation in a stream system. A relation was developed correlating vegetation length to sediment retention after flushing for flexibility and rigid vegetation.
HYDRAULIC GEOMETRY AND STREAM CHANNEL BEHAVIOR: A UNCERTAIN LINK1
Authors: Merigliano Michael F.
Published: June 2007

ABSTRACT: The at‐a‐station hydraulic geometry of stream channels can serve as a predictor of alluvial stream channel behavior. This geometry is the empirical relations describing changes in water surface width, mean depth, and mean velocity with changing discharge. The exponent values are correlated with channel morphology and behavior such as scour and fill, flow resistance, bank resistance, and competence. Channel behavior and morphology are apparently related, but some causes for effects are uncertain. Several studies, using empirical and theoretical bases, are reviewed here to illustrate the relation between hydraulic geometry and channel behavior, but the relations are not always consistent. Hydraulic geometry variables are easy to measure and readily available, but they do not always reflect what may be more important ones such as turbulence, the velocity distribution profile, and distribution and cohesion of sediment particles. This paper illustrates some of these problems, provides some solutions, and addresses need for more work to better predict stream channel behavior from hydraulic geometry
BIODIVERSITY AND ENVIRONMENTAL ETHICS: A PERSONAL REFLECTION1
Authors: Coufal James E.
Published: June 2007

ABSTRACT:A forester shares personal reflections on biodiversity, finding he must deal with the question of “What is biodiversity?” before dealing with “What is biodiversity good for?” Even before that, the complexity of the scientific and social aspects of biodiversity must be looked at to set a context. The author believes that biodiversity has scientific, recreational, wildness, natural history, and spiritual values and contributes to sustainability and productivity. Aesthetic values also are found to be very important, and the author concludes “that biodiversity has values that are worth protecting, even in the face of scientific uncertainty.” Personal reflection on environmental issues is necessary to fully understand what one believes, and to be an active participant in issues of environmental ethics.
MODELING FLOW IN THE EVERGLADES AGRICULTURAL AREA IRRIGATION/DRAINAGE CANAL NETWORK1
Authors: Windemuller P. , Anderson D. L. , Aalderink R. H. , Abtew W. , Obeysekera J.
Published: June 2007

ABSTRACT: The south Florida ecosystem and Lake Okeechobee are important water resource areas that have degraded due to changes in hydroperiod, water supply, and water quality. Approximately 56 percent of the total phosphorus in water discharged from the Everglades Agricultural Area (EAA) is in particulate form. Currently, farm‐level best management practices are being implemented in the effort to reduce total phosphorus and sediment in off‐farm discharges. The objective of this work was to develop and calibrate a model describing water movement in primary EAA canals as a first step to development of a water quality (i.e., nutrient, sediment) model. The Netherlands‐developed mechanistic flow and water quality model (DUFLOW) was adapted for the EAA. Flow, stage, geometry, canal network, and meteorological data, October 13, 1993, to February 13, 1994, were used to adapt and calibrate the DUFLOW model for EAA water level and flow in primary canals. Direct runoff discharge into the primary canals from farm‐pump stations was used as runoff input for the model. The model results are comparable to an independently‐calculated water balance for the EAA. The calibrated flow model will be the basis for the calibration of sediment and chemical transport in the future.
RECYCLING INPUT DATA DURING ANALYTIC ELEMENT MODELING NEAR INDIANAPOLIS, INDIANA1
Authors: Wittman Jack , Haitjema Henk , Studebaker Larry
Published: June 2007

ABSTRACT: Overlapping and adjacent ground water investigations are common in areas where aquifers are threatened by industrial development. In the Indianapolis area in Marion County, Indiana, a patchwork of ground water flow models have been used during the past 20 years to evaluate ground water resources and to determine the effects of local contamination. In every case these ground water models were constructed from scratch.

Site specific finite difference grids or finite element meshes inhibit the direct reuse of input data when the area of interest shifts. Because the aquifer is not discretized into a grid or mesh with analytic element models, there are unique opportunities for direct reuse of model input data. In two applications of this principle we illustrate how the newly emerging analytic element method allows a fairly straightforward reuse of model input data from previous models in the same general area. In analytic element models of Central Indiana, streams and their tributaries are represented in different resolutions. Input data items of several modeling studies are stored and cataloged on disk in such a manner that they can be selectively retrieved by a data management program PREPRO. In this manner, a new ground water model can be set up quickly with input data which have been previously defined and tested during model calibration.
INFILTRATION OF ATRAZINE AND METABOLITES FROM A STREAM TO AN ALLUVIAL AQUIFER1
Authors: Squillace Paul J. , Burkart Michael R. , Simpkins William W.
Published: June 2007

ABSTRACT: The infiltration of atrazine, deethylatrazine, and deisopropylatrazine from Walnut Creek, a tributary stream, to the alluvial valley aquifer along the South Skunk River in central Iowa occurred where the stream transects the river's flood plain. A preliminary estimate indicated that the infiltration was significant and warrants further investigation. Infiltration was estimated by measuring the loss of stream discharge in Walnut Creek and the concentrations of atrazine and its metabolites deethylatrazine and deisopropylatrazine, in ground water 1 m beneath the streambed. Infiltration was estimated before application of agrichemicals to the fields during a dry period on April 7, 1994, and after application of agrichemicals during a period of small runoff on June 8, 1994. On April 7, the flux of atrazine, deethylatrazine, and deisopropylatrazine from Walnut Creek into the alluvial valley aquifer ranged from less than 10 to 60 (μg/d)/m2, whereas on June 8 an increased flux ranged from 270 to 3060 (μg/d)/m2. By way of comparison, the calculated fluxes of atrazine beneath Walnut Creek, for these two dates, were two to five orders of magnitude greater than an estimated flux of atrazine to ground water caused by leaching from a field on a per‐unit‐area basis. Furthermore, the unit‐area flux rates of water from Walnut Creek to the alluvial valley aquifer were about three orders of magnitude greater than estimated recharge to the alluvial aquifer from precipitation. The large flux of chemicals from Walnut Creek to the alluvial valley aquifer was due in part to the conductive streambed and rather fast ground water velocities; average vertical hydraulic conductivity through the streambed was calculated as 35 and 90 m/d for the two sampling dates, and estimated ground water velocities ranged from 1 to 5 m/d.