bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECTS OF VARIABLE DISCHARGE SCHEMES ON DISSOLVED OXYGEN AT A HYDROELECTRIC STATION1
Authors: Mathur Dilip , McClellan Eric S. , Haney Susan A. 
Published: June 2007

ABSTRACT: The effects of variable discharges during the summer on the dissolved oxygen (DO) content and water temperature upstream and downstream of the Conowingo Hydroelectric Power Station were investigated. The DO dynamics are controlled primarily by meteorological factors that are independent of the mode of hydrostation operation. DO stratification occurred during the summer in Conowingo Pond, but thermal stratification was not observed. The magnitude and duration of off‐peak discharges including a run‐of‐the‐river operation did not affect DO stratification in Conowingo Pond; little vertical mixing occurred. However, strong winds and/or high river flows temporarily destroyed DO stratification. The run‐of‐the‐river operation or off‐peak continuous discharge schemes did not provide better DO conditions downstream of the hydrostation than the peaking operation with intermittent off‐peak releases.A statistical model predicted that a DO of 5 ppm occurs 0.6 miles downstream of the powerhouse when the natural river flow is consistently greater than 15,000 cfs and water temperature is less than 80°F. A mean daily DO of at least 4 ppm was predicted to occur over 80 percent of the time during the 92‐day summer period. Farther downstream (1.3 miles from the powerhouse) a mean daily DO of at least 4 ppm was predicted to occur 90 percent of the time in summer.
“Applicability of the t‐Test for Detecting Trends in Water Quality Variables,” by Robert H. Montgomery and Jim C. Loftis2
Authors: Helsel Dennis R. , Hirsch Robert M. 
Published: June 2007

SUMMARYMontgomery and Loftis (1987) have listed several situations for which the t‐test does not accurately reproduce Type I errors, and should therefore be avoided. Characteristics common to water quality data (skewness or other non‐normality, presence of outliers and less‐thans) also reduce the power of the t‐test, in relation to nonparametric alternatives.Thus if one is interested in reaching correct decisions when trends or differences exist, and not just when they do not, the t‐test should not be considered “robust” (in the sense of being generally applicable) when its assumptions are violated. Further, t‐tests assume that differences in means are relevant (the mean is a good measure of central tendency), and that data groups differ by some additive amount. When all of these assumptions are recognized, and in light of the availability of truly robust and comparatively powerful non‐parametric alternatives, we believe there is little applicability of the t‐test for detecting trends or differences in water quality variables.
MUNICIPAL RESPONSES TO VOLATILE ORGANIC COMPOUNDS IN WISCONSIN GROUND WATER1
Authors: Page G. William 
Published: June 2007

ABSTRACT: Contamination of ground water supplies with volatile organic compounds is a new and significant problem. Municipalities and their community water systems are often the first to discover ground water contamination because of the monitoring programs they are required to carry out. When contamination exceeds standards, some action is required.The responses of Wisconsin municipalities to volatile organic compounds that exceed standards in their ground water sources is described. Actions to protect human health are prompt, but the survey results indicate plumes of contaminated ground water are usually not treated. They may continue to migrate and contaminate other private and public wells.
OPTIMIZING THE RETURN FROM A JOJOBA PLANTATION UNDER SCARCE DATA CONDITIONS1
Authors: Wisniak Daniel , Oron Gideon 
Published: June 2007

ABSTRACT: There is a serious shortage of yield data for Jojoba (SIMMONDSIA CHINENSIS) from mature and cultivated plantations of ten years or older. Thus, the optimal quantities of water and fertilizers that are needed annually by a Jojoba plantation to achieve maximum profits were estimated from existing plantations.A computer model (IMSL subroutine ZXMWD) was used to determine a Mitscherlich yield function. An economic profit model that incorporates the yield function was then designed to maximize the profits. According to the net present value (NPV) criterion, the maximum yearly net profit is about $7800 per ha, which is achieved during the 11th growth year. The computed cumulative NPV is approximately $21,000 per ha for the entire 15‐year period. Similar profits were calculated when the model was tested to examine the NPV using different assumptions with respect to varying costs.
USE OF IN SITU MICROCOSMS FOR EVALUATING RESERVOIR WATER MANAGEMENT OPTIONS1
Authors: French Richard H. , Cooper James J. , Vigg Steven 
Published: June 2007

ABSTRACT: The use of in situ microcosms for performing reservoir trophic studies and aiding in the design of reservoir restoration programs are discussed. The site of this study was Lahontan Reservoir, Nevada, which has experienced water quality problems associated with monospecific blooms of blue‐green algae and hypolimnetic dissolved oxygen depletions. In situ microcosms were used to investigate the response of phytoplankton species composition to additions of the nutrients nitrogen, phosphorus, and the phosphorus precipitant aluminum sulfate. At the end of the 16‐day experimental period, the microcosms receiving the phosphate treatments yielded the highest standing crops of algae and the greatest percentage composition of blue‐green algae. The microcosms receiving the nitrate treatment exhibited greater initial algal concentrations followed by a decline in photoplankton, which coincided with an increase in the zoo‐plankton population.The results presented here suggest that microcosms can be a cost‐effective method for assessing reservoir water quality and planning restoration programs.
FUNDAMENTAL INVESTIGATION OF GRAVITY CURRENTS WITH VARYING DENSITY1
Authors: Warwick John J. , Murray Willard A. 
Published: June 2007

ABSTRACT: A one‐dimensional, gradually varying, non‐uniform, flow equation is developed to describe the movement of a variable density gravity current through a reservoir. A linearly decreasing underflow density function is used to investigate the effect of in‐reservoir density reduction on typical gravity current flow profiles. Only two types of flow profiles are found to exist for varying density underflows: Type I profiles where the underflow asymptotically approaches a horizontal surface, and Type III profiles where the underflow vertically approaches critical depth. Type I profiles pass through a transitional depth as the underflow density approaches that of the upper layer.Results indicate that a reservoir can be segmented into four distinct spatial regions with well defined flow profile characteristics. The location of these regions allows the sketching of interfacial flow profiles along with identifying the location of transitional depth conditions. Transitional depth conditions are utilized as the logical starting point for Type I flow profile numerical computation. (KEY WORDS: density; fluid flow; reservoirs; hydraulics.)
THE USE OF WATER RESOURCE INFORMATION: THE SECOND NATIONAL WATER ASSESSMENT1
Authors: Osborn C. Tim. , Shabman Leonard 
Published: June 2007

ABSTRACT: Despite discontinuation of periodic National Water Assessments resulting from the dissolution of the Water Resources Council (WRC), information that assesses the Nation's water quantity and quality remains important to those involved in water resource management. However, citing limited apparent use of the WRC's Second National Water Assessment, some have implied that past assessments have been of minimal value to water resource management and policy. This has led to numerous suggestions for modifying the assessment process in the belief that such changes would increase the perceived value of future national water assessment efforts.This paper examines use of the Second National Water Assessment by water resource managers and decision makers. Based upon the individual and organizational characteristics of users, conclusions are drawn regarding the nature of national assessment use. The paper concludes that the primary value of national water assessment stems from the fact that it provides a unifying general description of the Nation's water resource situation and that it serves as a symbolic statement that a rational thought process guides national water policy. (KEY WORDS: National Water Assessment; information use; water planning; water policy; organizational decision making; logit analysis.)
OXYGEN DEMAND IN ICE COVERED LAKES AS IT PERTAINS TO WINTER AERATION1
Authors: Ellis Christopher R. , Stefan Heinz G. 
Published: June 2007

ABSTRACT: Winterkill, the death of fish under ice due to oxygen deficiency, threatens hundreds of shallow lakes in the upper Midwest of the United States every winter. For decades, attempts have been made to prevent winterkill, usually through aeration, with mixed results. In large part, the failure of strategies to prevent winterkill can be linked to a lack of understanding of winter limnology and in particular, of oxygen dynamics under ice.Most winterkill lakes behave as closed systems with regard to oxygen. Consequently, the oxygen content of an ice and snow covered lake is essentially a function of the amount of initial storage and the rate of depletion. Should the stored oxygen be insufficient to prevent near anoxia before melting of the ice cover occurs, winterkill will result.Most oxygen consumption in ice covered lakes is due to bacterial respiration and chemical oxidation at the sediment/water interface, the remainder occurring in the water column. Oxygen consumption (and thus depletion) is a function of the velocity and oxygen concentration of the near sediment water. This is due to the fact that oxygen transport to the sediment is mediated by a diffusive boundary layer adjacent to the sediment surface. Winter oxygen depletion rates decrease when the oxygen concentration of the overlying water falls below about 3 mg/l. Aeration techniques which increase the oxygen concentration and velocity of the near‐sediment water also increase the oxygen consumption (depletion) rate.
WATER AND WATER RIGHTS TRANSFERS: A NEW POLICY FOR NEBRASKA1
Authors: Gilliland Martha W. , Wallin Gerald P. , Smaus Ronald 
Published: June 2007

ABSTRACT: Nebraska has abundant supplies of high quality surface and ground water. The U.S. Supreme Court decision in 1982, declaring ground water to be an article of commerce, is widely perceived as giving neighboring states easier access to Nebraska water. Some neighboring states, particularly Colorado and Wyoming, are in water short situations. Additionally, current legal restrictions on certain types of transfers within the State could be inhibiting the “highest and best use” of Nebraska's water. Thus, in 1987 the Nebraska Legislature called for the development of a new water policy for Nebraska that would promote the economically efficient use of water, yet protect the environment as well as the rights of individuals (for example, third parties) and the public.Through an interagency study employing an extensive public involvement process, a policy to be recommended to the Legislature in 1989 emerged. The policy revises the basic definition of water rights and transfers and eliminates most of the inconsistencies in the water allocation system by treating most types of water resources, most types of water users, and most locations of use similarly in the permitting process. (The principal exception is the individual irrigator using ground water on the overlying land where overlying land is one government surveyed section; such use is not defined to be a transfer nor is a permit required.) An impact assessment would be required of most new water uses except on site uses of ground water. Compensation measures could be specified as a condition of the permit where appropriate. The permit would be issued only if the benefits of the proposed transfer clearly outweigh adverse effects that could not be avoided or effectively compensated. The policy allows for the sale or lease of “salvaged” water. It calls for the State to facilitate transfers by acting as a clearinghouse for potential buyers and sellers, and it allows the State to sponsor water projects. An annual fee to be paid by many water users, in order to provide a fund for compensation and for state sponsored water projects, was proposed. However, it met with extensive opposition. Thus, the policy recommends only that the Legislature examine potential funding programs and equitable user fees.
WATERSHED CONFIGURATION AND GEOGRAPHIC INFORMATION SYSTEM PARAMETERIZATION FOR SPUR MODEL HYDROLOGIC SIMULATIONS1
Authors: Sasowsky Kathryn Connors , Gardner Thomas W. 
Published: June 2007

ABSTRACT: A grid cell geographic information system (GIS) is used to parameterize SPUR, a quasi‐physically based surface runoff model in which a watershed is configured as a set of stream segments and contributing areas. GIS analysis techniques produce various watershed configurations by progressive simplification of a stream network delineated from digital elevation models (DEM). We used three watershed configurations: ≥ 2nd, ≥ 4th, and ≥ 13th Shreve order networks, where the watershed contains 28, 15, and 1 channel segments with 66, 37, and 3 contributing areas, respectively.Watershed configuration controls simulated daily and monthly sums of runoff volumes. For the climatic and topographic setting in southeastern Arizona the ≥ 4th order configuration of the stream network and contributing areas produces results that are typically as good as the ≥ 2nd order network. However both are consistently better than the ≥ 13th order configuration. Due to the degree of parameterization in SPUR, model simulations cannot be significantly improved by increasing watershed configuration beyond the ≥ 4th order network. However, a range of Soil Conservation Service curve numbers derived from rainfall/runoff data can affect model simulations. Higher curve numbers yield better results for the ≥ 2nd order network while lower curve numbers yield better results for the ≥ 4th order network.
IDENTIFICATION OF DISSOLVED‐CONSTITUENT SOURCES IN MINE‐SITE GROUND WATER USING BATCH MIXING1
Authors: Clark Gregory M. , Williams Robert S. 
Published: June 2007

ABSTRACT: Batch‐mixing experiments were used to help identify lithologic and mineralogic sources of increased concentrations of dissolved solids in water affected by surface coal mining in northwestern Colorado. Ten overburden core samples were analyzed for mineral composition and mixed with distilled water for 90 days until mineral‐water equilibrium was reached. Between one day and 90 days after initial contact, specific conductance in the sample mixtures had a median increase of 306 percent. Dissolved‐solids concentrations ranged from 200 to 8,700 mg/L in water samples extracted from the mixtures after 90 days.Mass. balance simulations were conducted using the geochemical models BALANCE and WATEQF to quantify mineral‐water interactions occurring in five selected sample mixtures and in water collected from a spring at a reclaimed mine site. The spring water is affected by mineral‐water interactions occurring in all of the lithologic units comprising the overburden. Results of the simulations indicate that oxidation of pyrite, dissolution of dolomite, gypsum, and epsomite, and cation‐exchange reactions are the primary mineral‐water interactions occurring in the overburden.Three lithologic units in the overburden (a coal, a sandstone, and a shale) probably contribute most of the dissolved solids to the spring water. Water sample extracts from mixtures using core from these three units accounted for 85 percent of the total dissolved solids in the 10 sample extracts. Other lithologic units in the overburden probably contribute smaller quantities of dissolved solids to the spring water.
EFFECTS OF WOODY VEGETATION ON SANDY LEVEE INTEGRITY1
Authors: Shields F Douglas , Gray Donald H. 
Published: June 2007

ABSTRACThe influence of woody vegetation on the reliability of a sandy levee was investigated using field data in seepage and slope stability analyses. Field data were collected from selected sites within a 10‐km segment of a channel levee on the Sacramento River near Elkhorn, California. Root architecture and distribution were determined using the profile‐wall method in which root cross sections were exposed in the vertical wall of an excavated trench. Transects running both parallel and perpendicular to the crest of the levee were excavated at six sites. Each site was dominated by different plant species: five sites were adjacent to trees or woody shrubs, while one supported only herbaceous growth. Lateral plant roots were primarily restricted to, and modified, the near‐surface soil horizons to a depth of approximately 1 meter. Root area ratios (RARs) did not exceed 2.02 percent and generally decreased exponentially with depth. At depths greater than 20 cm, mean RARs for sites dominated by wood species were not significantly different from the mean RAB for the herbaceous site. No open voids clearly attributable to plant roots were observed. Roots reinforced the levee soil and increased shear resistance in a measurable manner. Infinite slope and circular arc stability analyses were performed on the landward and riverward slopes under different hydraulic loading conditions. Infinite slope analyses indicated increasing root area ratio from 0.01 percent to 1 percent increased the factor of safety from less than one to more than seven. Circular arc analyses indicated that even the lower measured root concentrations sufficed to increase safety factors for arcs with maximum depths of about 1 m from less than one to about 1.2. Our findings suggest that allowing woody shrubs and small trees on levees would provide environmental benefits and would enhance structural integrity without the hazards associated with large trees such as wind‐throwing.
MODELING PERCOLATION LOSSES FROM A PONDED FIELD UNDER VARIABLE WATER‐TABLE CONDITIONS1
Authors: Kalita P. K. , Kanwar R. S. , Rahman M. A. 
Published: June 2007

ABSTRACT: A numerical simulation model was developed to predict the vertical and lateral percolation losses from a ponded agricultural field. The two‐dimensional steady‐state unsaturated/ saturated flow equation was solved using the finite‐difference technique. A constant ponding depth was maintained at the soil surface with different water table conditions in an application of the model for rice fields bordered by bunds. Field experiments were conducted for two different water table depths to collect data on the spatial distribution of volumetric soil‐moisture content for model verification. The measured soil‐moisture content values were found to be in close agreement with those predicted by the model.The sensitivity analysis of the model with selected hydrologic conditions shows that the model is most sensitive to the values of saturated hydraulic conductivity, but relatively less sensitive to water table depth, ponding depth, and evaporation rate from the soil surface. It implies that, in a ponded rice field condition, the lateral and vertical percolation losses are mostly governed by the hydraulic conductivity of the soil. The vertical percolation losses were almost equal to the saturated hydraulic conductivity values and, in most cases, these losses increased with deeper water table depths. The lateral percolation losses also increased with deeper water table depths; however, these losses were relatively small in comparison to the vertical percolation losses. The vertical and lateral percolation losses increased with the increase in ponding depths. The lateral percolation losses through the bund decreased when the evaporation losses increased from the soil surface. The results of this study indicate that the percolation losses from a ponded field may be predicted accurately for a wide range of soil and hydrological conditions when the values of hydraulic conductivity, evaporation rate, depth of ponding, and water table depth are accurately known.
EFFECTS OF LIME‐SLUDGE DISCHARGE ON AN ARCTIC RIVER1
Authors: Tumeo Mark A. 
Published: June 2007

ABSTRACT: The Fairbanks Water Treatment Plant in Fairbanks, Alaska, processes approximately 3 MGD of drinking water using lime softening. Approximately 0.3 MGD of lime‐sludge from the treatment process is combined with effluent from a nearby power plant and discharged to the Chena River. There is little information available on the impact of water‐treatment sludge discharges, and virtually no information on the impacts of such discharges in polar environments. Concern surrounding the discharge of water treatment sludges have centered on alum‐sludge due to the potential toxic effects of aluminum. Because of the relatively benign composition of lime‐sludge, very little research has been published. However, there is the possibility that discharge of solids will result in sedimentation, accumulation of solids, and subsequent impacts on benthic organisms. This paper reports on the results of a study to determine if lime‐sludge discharge from the water treatment plant is adversely impacting the river environment. The results provide basic information on the important variables of concern in lime‐discharges to rivers.Samples from the discharge of the water treatment plant and combined water treatment plant/power plant effluent were collected weekly over a one‐year period, and in‐stream benthic and water column samples were collected biweekly during the fall and spring. Sediment and water quality data indicate that while significant accumulation of sludge solids is found downstream of the water treatment plant outfall, they are flushed out of the system by spring flows, which are significantly increased by snow melt. This process is most likely repeated on a yearly cycle.Hence, the data suggest that the FMUS water treatment plant's discharge of lime‐sludge is probably not adversely impacting the river. More generally, this may indicate that the natural flow variations and sediment‐laden characteristics of Arctic, glacier‐fed rivers may assimilate large quantities of nonputrescible solids without significant changes in the natural river environment. Further research in this area is required to verify this conclusion.
SPATIAL COMPARABILITY OF THE PALMER DROUGHT SEVERITY INDEX1
Authors: Guttman Nathaniel B. , Wallis James R. , Hosking J. R. M. 
Published: June 2007

ABSTRACT:The Palmer Drought Severity Index, which is intended to be of reasonable comparable local significance both in space and time, has been extensively used as a measure of drought for both agricultural and water resource management. This study examines the spatial comparability of Palmer's (1965) definition of severe and extreme drought. Index values have been computed for 1035 sites with at least 60 years of record that are scattered across the contiguous United States, and quantile values corresponding to a specified index value were calculated for given months and then mapped.The analyses show that severe or extreme droughts, as defined by Palmer (1965), are not spatially comparable in terms of identifying rare events. The wide variation across the country in the frequency of occurrence of Palmer's (1965) extreme droughts reflects the differences in the variability of precipitation, as well as the average amount of precipitation. It is recommended first, that a drought index be developed which considers both variability and averages; and second, that water resource managers and planners define a drought in terms of an index value that corresponds to the expected quantile (return period) of the event.