bluuebunny/crossref_metadata_2025 huggingface dataset:
EVALUATING RELIABILITY OF STORAGE SCHEMES WITH DENDROHYDROLOGY AND THE HURST PHENOMENON1
Authors: Turner Kenneth M.
Published: June 2007

ABSTRACT: The mean annual flow at a damsite during a water project yield study of several decades may differ considerably from the mean flow of several hundred years. The frequency of the most severe droughts of record may be much different than apparent from the historical record as well. Dendrohydrology and the Hurst Phenomenon provide means to evaluate the validity of the study period for project reliability analysis. The most severe hydrologic drought (1928–1934) affecting the watersheds of the Sacramento River and tributaries in Northern California during the 75‐year period 1906–1980 was also the worst drought in 421 years (1560–1980). In contrast, the most severe drought (1945–1951) in the Santa Ynez River watershed in Santa Barbara County, California, during the 62‐year period 1918–1979 was the ninth worst drought in 443 years (1537–1979). Thus, in one case the drought risk indicated by the dendrohydrologic time series would actually be less; in the other, actual risk would be greater than perceived from the historical record. In the absence of a dendrohydrologic prehistoric time series, Hurst Phenomena would have provided clues to this outcome. Hurstian plotting of the accumulated deviation from the mean for long time series facilitates observation of the wet‐dry regime of the examples and identification of characteristics that should be accounted for in water development planning.
CURVE NUMBERS AND GREEN‐AMPT EFFECTIVE HYDRAULIC CONDUCTIVITIES1
Authors: Nearing M. A. , Liu B. Y. , Risse L.M. , Zhang X.
Published: June 2007

ABSTRACT: The SCS curve number method is an accepted method for estimating surface water runoff caused by rainfall. Several modern process‐based hydrologic models, including the Water Erosion Prediction Project (WEPP) model, use the Green‐Ampt infiltration equation, but the basis for selecting model parameters is not as comprehensive as for curve number selection. The purpose of this study was to quantitatively relate curve numbers to Green‐Ampt effective conductivity parameters, Ke, so that the information avail. able relative to application of curve number technology may be applied to WEPP for predicting runoff from rainfall. Data used to develop relationships included descriptions of 43 soils, CLIGEN‐generated weather information for ten geographic locations in the U.S., and eight different types of cropping practices. Values of Ke were derived by optimizing WEPP model output to match that predicted by curve numbers for a 20‐year weather sequence. Relationships were developed to describe the optimized Ke values for both fallow and cropped conditions. The relationships were tested on approximately 350 plot years of measured data from 11 runoff and erosion stations in the U.S. and shown to perform as well as or better than the SCS curve number approach for individual storm predictions of runoff volumes.
MODELING WATER UTILITY FINANCIAL PERFORMANCE1
Authors: Jordan Jeffrey L. , Witt Harvey J. , Wilson James R.
Published: June 2007

ABSTRACT: The purpose of this paper is to present a theory and model for assessing the financial health of public water systems. Using financial information from 25 water utilities in Georgia, the paper seeks to identify the causal relationships between the financial performance of a water utility and its fiscal position. The need for a theoretical understanding of water utility financial health is the result of the increasingly stringent performance requirements under the Safe Drinking Water Act (SDWA). The issue has become particularly important for small water systems that will be exposed to significant financial demands. A set of financial ratios were developed and tested in a model that was based on liquid asset theory. The model contained five variables designed to account for the size of liquid assets, current debt, cash‐flow, and the level of expenses. The variables fit the need of water utilities: to provide an adequate level of operation and maintenance to meet current and future system needs as well as SDWA standards.
URBAN INFLUENCE ON PHOSPHORUS AND SEDIMENT LOADING OF WEST POINT LAKE, GEORGIA1
Authors: Emmerth Phillip P. , Bayne David R.
Published: June 2007

ABSTRACT: West Point Lake is a 10,360 ha mainstream impoundment of the Chattahoochee River located 95 kilometers downstream of Atlanta, Georgia. Origins and magnitude of external total phosphorus (TP) and total suspended solids (TSS) loads from the West Point Lake basin were estimated over a one‐year period. Partitioning the drainage basin allowed the sources of these loads to be determined. The upper subbasin area, from Franklin, Georgia, to the headwaters of the Chattahoochee River, contributed 96 percent of the discharge and 97 percent of the TP and TSS loads into West Point Lake. The lower subbasin area, from Franklin to West Point Lake dam, only contributed 3 percent of the TP and TSS loads. Ninety‐one percent and 87 percent of the TP and TSS loads, respectively, from the upper subbasin originated from the Atlanta area. Point sources discharged 70 percent and 3 percent of the upper subbasin TP and TSS loads, respectively. A large portion (66 percent) of the TP from the upper subbasin was in the bioavailable form.
JUVENILE BLUEBACK HERRING (ALOSA AESTIVALIS) SURVIVAL VIA TURBINE AND SPILLWAY1
Authors: Mathur Dilip , Heisey Paul G. , McGrath Kevin J. , Tatham Thomas R.
Published: June 2007

ABSTRACT: The 48 h survival of emigrating juvenile blueback herring (Alosa aestivalis) was estimated at 96 ± 6.7 percent in passage through a Kaplan‐type turbine and at 88.3 ± 10.7 percent (90 percent confidence interval) over a spillway (3.7 m high and spillage of 1.2 m3/s) of a low‐head hydro darn (8.3 m). These results suggest that diversion of juvenile alosids over spillways may not be assumed to be a totally benign strategy without obtaining site‐specific data. A remarkable similarity in survival rates of fish observed through turbine routes in this study and others suggests that these trends may be common. However, due to a lack of sufficient data, such a conclusion cannot be made for survival over spillways.
TEMPORAL AND GEOMORPHIC VARIATIONS OF STREAM STABILITY AND MORPHOLOGY: MAHOGANY CREEK, NEVADA1
Authors: Myers Thomas J. , Swanson Sherman
Published: June 2007

ABSTRACT: Detailed studies of long‐term management impacts on rangeland streams are few because of the cost of obtaining detailed data replicated in time. This study uses government agency aquatic habitat, stream morphologic, and ocular stability data to assess land management impacts over four years on three stream reaches of an important rangeland watershed in northwestern Nevada. Aquatic habitat improved as riparian vegetation reestablished itself with decreased and better controlled livestock grazing. However, sediment from livestock disturbances and road crossings and very low stream flows limited the rate of change. Stream type limited the change of pool variables and width/depth ratio, which are linked to gradient and entrenchment. Coarse woody debris removal due to previous management limited pool recovery. Various critical‐element ocular stability estimates represented changes with time and differences among reaches very well. Ocular stability variables tracked the quantitative habitat and morphologic variables well enough to recommend that ocular surveys be used to monitor changes with time between more intensive aquatic surveys.
ASSESSING THE ECONOMIC BENEFITS OF GROUND WATER FOR ENVIRONMENTAL POLICY DECISIONS1
Authors: Bergstrom John C. , Boyle Kevin J. , Job Charles A. , Jo Kealy Mary
Published: June 2007

ABSTRACT: The full range of environmental and economic services of ground water need to be accounted for in policy decisions. Non‐recognition of these services imputes a lower value for the ground water resource in establishing policies. We describe a conceptual framework for identifying and measuring the economic value of groundwater. The valuation framework links changes in physical characteristics of ground water to services provided by ground water and the economic effects of changes in ground water services. In addition to the framework, we develop a general protocol to follow for assessing the benefits of ground water policies. Application of the protocol will aid in establishing structure and consistency across policy assessments and improve the accuracy and completeness of benefit estimates, avoid double‐counting problems, and eliminate duplication of ground water valuation efforts.
RELATIONSHIPS BETWEEN PARTICLE MOVEMENT AND CHANNEL MORPHOLOGY IN SOME NORTHERN IDAHO STREAMS1
Authors: Hallisey Judy E. , Belt George H.
Published: June 2007

ABSTRACT: Data were collected in 1992 from 17 mountain streams located within fine‐ to coarse‐grained schist formations on the Idaho Panhandle National Forests. These were used to examine predictive relationships potentially useful in monitoring stream channel stability and fishery habitat. Channel morphology, sediment, and lithological data were obtained at 123 riffle sites. An analysis of materials deposited on gravel bars showed that at most sites, critical grain size, calculated using Duboy's tractive force equation, often does not provide accurate estimates of particle sizes moved at bankfull discharge. The tractive force equation gave reasonable estimates (± 10 mm) at 16 percent of the sites, but significantly over‐ or underestimated the sizes at the remaining sites. Regression and discriminant analysis showed that the relationship between critical grain size and the geometric mean diameter of material deposited on gravel bars was influenced most by the substrate size, slope, and width‐to‐depth ratio. Similarly, lithology was correlated with the size of particles moved. Particle sizes moved at bankfull discharge were not well correlated with residual pool depth or pool length.
WATER QUALITY MONITORING: WHERE'S THE BEEF?1
Authors: Ward Robert C.
Published: June 2007

ABSTRACT: Water quality monitoring, as a function of society's efforts to manage the environment, is the contact mechanism that management and the public has with the actual water quality in the environment. Water quality monitoring has been studied extensively for many years to ensure that it produces information about water quality conditions. Current efforts to reduce government spending will have negative impacts on those government functions deemed to be non‐responsive to the needs of the public. How well does water quality monitoring inform taxpayers about the status and trends in water quality conditions in the United States? This paper reviews a number of past efforts to “improve” water quality monitoring, discusses barriers to such improvement, and suggests ways that monitoring can be made more accountable for the information it should be producing for public understanding of water quality conditions. In particular, the need for standardization in data analysis and reporting of information to the public, is highlighted.
PERSISTING SEDIMENT YIELDS AND SEDIMENT DELWERY CHANGES1
Authors: Faulkner Douglas , McIntyre Sherwood
Published: June 2007

ABSTRACT: The Buffalo River is a tributary to the Mississippi River in west‐central Wisconsin that drains a watershed dominated by agricultural land uses. Since 1935, backwater from Lock and Dam 4 on the Mississippi River has inundated the mouth of the Buffalo's valley. Resurveys of a transect first surveyed across the lake in 1935 and cesium‐137 dating of backwater sediments reveal that sedimentation rates at the Buffalo's mouth have remained unchanged since the mid‐1940s. Study results indicate that sediment yields from the watershed have persisted at relatively high levels over a period of several decades despite pronounced trends toward less cultivated land and major efforts to control soil erosion from agricultural land. The maintenance of sediment yields is probably due to increased channel conveyance capacities resulting from incision along some tributary streams since the early 1950s. Post‐1950 incision extended the network of historical incised tributary channels, enhancing the efficient delivery of sediment from upland sources to downstream sites.
A SIMPLIFIED MODEL FOR PREDICTING DAILY TRANSMISSION LOSSES IN A STREAM CHANNEL1
Authors: Rao Chris X. , Maurer Edwin P
Published: June 2007

ABSTRACT: A simplified approach for modeling transmission losses in a stream is presented. A theory relating seepage from a channel with the depth of flow is simplified to a one‐parameter relationship. A power relationship is then utilized for the stage‐discharge relationship, which is coupled with the seepage relationship. This combined equation is integrated over the channel reach to arrive at a general model for seepage loss through the reach, with one parameter needing calibration. An example is provided showing the development of the relationship and the calibration technique for the parameter. The results are shown, emphasizing the use of the model for simulation of channel transmission losses at low and moderate flow conditions.
STABLE ISOTOPE CHARACTERIZATION OF THE IMPACTS OF ARTIFICIAL GROUND WATER RECHARGE1
Authors: Ma Li , Spalding Roy F
Published: June 2007

ABSTRACT: Stable isotopes of deuterium and oxygen‐18 of surface and ground water, together with anion concentrations and hydraulic gradients, were used to interpret mixing and flow in ground water impacted by artificial recharge. The surface water fraction (SWF), the percentage of surface water in the aquifer impacted via recharge, was estimated at different locations and depths using measured deuterium/hydrogen (DIH) ratios during the 1992, 1993, and 1994 recharge seasons. Recharged surface water completely displaced the ground water beneath the recharge basins from the regional water table at 7.60 m to 12.16 m below the land surface. Mixing occurred beneath the recharge structures in the lower portions of the aquifer (>12.16 m). Approximately 12 m down‐gradient from the recharge basin, the deeper zone (19.15 m depth) of the primary aquifer was displaced completely by recharged surface water within 193, 45, and 55 days in 1992, 1993, and 1994, respectively. At the end of the third recharge season, recharged surface water represented ∼50 percent of the water in the deeper zone of the primary aquifer ∼1000 m downgradient from the recharge basin. A classic asymmetrical distribution of recharged surface water resulted from the recharge induced horizontal and vertical hydraulic gradients. The distribution and breakthrough times of recharged surface water obtained with stable isotopes concurred with those of major anions and bromide in a tracer test conducted during the 1995 recharge season. This stable isotope procedure effectively quantified mixing between surface and ground water.
OFF‐LINE STORMWATER DETENTION SYSTEMS1
Authors: Nix Stephan J. , Durrans S. Rocky.
Published: June 2007

ABSTRACT: This paper looks at the use of off‐line detention systems as a means of stormwater management. Conventional detention basins are typically designed and built as in‐line systems in which all runoff is directed to the basin. Off‐line systems are designed so that only a portion of the runoff is directed to the basin. Several simulation experiments were run to examine the behavior of in‐line and off‐line systems designed to reduce the peak flow from a developed area to the pre‐development level. The results demonstrate that off‐line systems require considerably less storage than in‐line systems to achieve the same management goal. The results also show that off‐line and in‐line systems have significantly different flow‐duration characteristics with the off‐line system generally producing lower flows over longer periods. Unfortunately, off‐line systems may exacerbate downstream flooding problems, especially when used in the upper portions of a watershed. Nevertheless, an off‐line system can be an alternative to in‐line detention in many cases.
OPTIMIZATION MODELING OF A NEW FACILITY FOR THE CALIFORNIA STATE WATER PROJECT1
Authors: Lefkoff L. Jeffrey , Kendall Donald R.
Published: June 2007

ABSTRACT: A non‐linear optimization model is applied to the California State Water Project (SWP) and portions of the Central Valley Project (CVP). The model accounts for the major hydrologic, regulatory, and operational features of both projects. The model maximizes long‐term SWP yields over a 70‐year period, using a quarterly time step. The potential for increased yield associated with a proposed facility improvement is evaluated with the model. The proposed facility is an extension of the Folsom‐South Canal, which would allow water to be conveyed from the American River below Folsom Reservoir into New Melones Reservoir on the Stanislaus River or into the California Aqueduct. Model results indicate that extension of the Folsom‐South Canal has the potential to increase SWP yields by 13 percent.
EVAPOTRANSPIRATION MEASUREMENTS AND MODELING FOR THREE WETLAND SYSTEMS IN SOUTH FLORIDA1
Authors: Abtew Wossenu
Published: June 2007

ABSTRACT: At the Everglades Nutrient Removal project in south Florida, three lysimeters were installed to measure daily evapotranspiration (ET) rates from cattails (Typha domingensis), mixed marsh vegetation, and an open water/algae system. The cattail lysimeter began operation in February 1993. The mixed marsh vegetation lysimeter began operation in January 1994, and the open water lysimeter with occasional algae cover began operation in December 1993. The mean measured ET rate was 3.6 mm, 3.5 mm, and 3.7 mm per day for the cattail, mixed marsh vegetation, and open water/algae system, respectively. High resolution weather data were continuously measured at the site. Six models were applied to estimate daily ET rates of the three systems. The Penman‐Monteith equation best estimated ET of cattail and mixed marsh vegetation, and the Penman Combination equation was most suitable for the open water/algae system. Empirical equations based on solar radiation and maximum temperature produced estimates of daily ET from the three systems that are comparable to models that require many more parameters. In cases where limited data is available, the calibrated simple models can be used to estimate ET from wetlands in south Florida.
AGRICULTURAL LAND USE EFFECTS ON NITRATE CONCENTRATIONS IN A MATURE KARST AQUIFER1
Authors: Boyer Douglas G. , Pasquarell Gary C.
Published: June 2007

ABSTRACT: The impact on water quality by agricultural activity in karst terrain is an important consideration for resource management within the Appalachian Region. Karst areas comprise about 18 percent of the Region's land area. An estimated one‐third of the Region's farms, cattle, and agricultural market value are on karst terrain. Nitrate concentrations were measured in cave streams draining two primary land management areas. The first area was pasture serving a beef cow‐calf operation. The second area was a dairy. Nitrate‐N concentrations were highest in cave streams draining the dairy and a cave stream draining an area of pasture where cattle congregate for shade and water. The dairy contributed about 60 to 70 percent of the nitrogen load increase in the study section of the cave system. It was concluded that agriculture was significantly affecting nitrate concentrations in the karst aquifer. Best management practices may be one way to protect the ground water resource.
POSTFIRE SUSPENDED SEDIMENT FROM YELLOWSTONE NATIONAL PARK, WYOMING1
Authors: Ewing Roy
Published: June 2007

ABSTRACT: Wildfires in 1988 burned over 2000 square miles of the greater Yellowstone area in Montana and Wyoming in the largest fires in the history of Yellowstone National Park (YNP). A four‐year postfire study to estimate fire‐related changes in suspended sediment transport on the Yellowstone River and its principal tributary in YNP, the Lamar River, benefitted from a recently completed three‐year prefire baseline study. Both studies took daily depth‐integrated samples from April through September. Fire‐related changes in suspended sediment were distinguished from natural climatic variations by two methods: comparison of forecast postfire sediment loads estimated with prefire sediment‐rating equations to measured postfire loads; and by postfire changes in suspended sediment load expressed per unit volume runoff. Both methods indicated postfire sediment increases that varied according to season. The higher elevation Lamar River basin had little postfire increase in spring snowmelt season sediment but large increases in summer sediment load. The Yellowstone River had postfire increases in sediment load for the spring but did not reflect the large summer increases of its upstream tributary. The reasons for the difference in postfire snowmelt sediment response are unclear but may relate to basin elevation differences, the effects of unburned watersheds, and cooler postfire springs. The few high streamflow snowmelt events in the postfire period mitigated postfire sediment increases.
PHOSPHORUS ASSIMILATION IN A STREAM SYSTEM OF THE LAKE OKEECHOBEE BASIN1
Authors: Reddy K. R. , Flaig E. , Scinto L. J. , Diaz O. , DeBusk T. A.
Published: June 2007

ABSTRACT: The ability to predict how streams and wetlands retain phosphorus (P) is critical to the management of watersheds that contribute nutrients to adjacent aquatic systems such as lakes. Field and laboratory experiments were conducted to determine the P assimilatory capacity of a stream (Otter Creek) in the Taylor Creek/Nubbin Slough Basin located north of Lake Okeechobee, Florida. Dominant soils in this basin are sandy Spodosols; landuse is primarily dairy farms and beef cattle pastures. Estimates of P assimilation show that sediments assimilate approximately 5 percent of the P load. Phosphorus assimilation rates in the stream were estimated using first‐order relationships based on the total P concentration of the water column as a function of distance from the primary source. This method assumes minimal lateral inputs. Stream lengths required for one turnover in P assimilation were estimated to be in the range of 3–16 km. Laboratory studies using intact sediment cores indicated a P assimilation rate of 0.025 m day−1, and equilibrium P concentration of 0.16 ± 0.03 mg L−1 in the water column. Dissolved P concentration gradients in the sediments showed upward flux of P at water column P concentration of <0.16 mg L−1. Approximately 56–77 percent of the P assimilated in the above‐ground vegetation during active growth was released or translocated within six months of senesence, suggesting short‐term storage in above‐ground vegetation. Bottom sediments and recalcitrant detrital plant tissue provide for long‐term P assimilation in the creek. Although stream sediments have the potential to adsorb P, high flow rate and low contact period between water and sediment limits this process.
FACTORS AFFECTING HERBICIDE YIELDS IN THE CHESAPEAKE BAY WATERSHED, JUNE 19941
Authors: Hainly Robert A. , Kahn Joan M.
Published: June 2007

ABSTRACT: Median concentrations and instantaneous yields of alachlor, metolachlor, atrazine, cyanazine, and simazine were generally highest at sites in the Lower Susquehanna River Basin and in agricultural subbasins. Instantaneous herbicide yields are related to land use, hydrogeologic setting, streamflow yield, and agricultural row cropping practices. The significance of these relations may be affected by the interdependence of the factors. The percentage of basin area planted in corn is the most influential factor in the prediction of herbicide yield. Instantaneous yields of all five herbicides measured in June 1994 related poorly to averaged 1990–94 herbicide use. Annually averaged herbicide‐use data are too general to use as a predictor for short‐term herbicide yields. An evaluation of factors affecting herbicide yields could be refined with more‐current land use and land cover information and a more accurate estimate of the percentage of basin area planted in corn. Factors related to herbicide yields can be used to predict herbicide yields in other basins within the Chesapeake Bay watershed and to develop an estimate of herbicide loads to Chesapeake Bay.
TEACHING WATER RESOURCES POLICY TO UNWERSITY SCIENCE AND ENGINEERING STUDENTS: OPPORTUNITIES AND CHALLENGES1
Authors: Goldfarb William
Published: June 2007

ABSTRACT: Effectively teaching water resources policy to university science and engineering students is both important and difficult. Most careers in the water resources field require an understanding of the comprehensive governmental regulatory structure affecting water use. Also, few science and engineering curricula encourage their students to take policy courses. Successful approaches to teaching water resources policy might include epistemological comparisons, case studies, issue maps, and interactive simulations. Obstacles to the effective teaching of this subject include students' insufficient preparation and student disdain and cynicism. These obstacles may be mitigated by requiring a prerequisite, developing a glossary of policy‐related terms, and introducing the course through lectures emphasizing realistic views of the water resources management field and the nature of the American political system.
SPRING RUNOFF AND DRAINAGE N AND P LOSSES FROM HOG‐MANURED CORN1
Authors: Gangbazo G. , Pesant A. R. , Côté D. , Barnett G. M. , Cluis D.
Published: June 2007

ABSTRACT:A two‐year study was conducted to assess the effect of hog manure on the losses of nitrogen and phosphorus in runoff and drainage from grain‐corn (Zea maysL.) plots, and the importance of spring versus annual loads. Treatments consisted of mineral N‐P‐K fertilizer applied at rates of 152 kg N ha‐1, 35 kg P ha‐1, and 86 kg K ha‐1; and hog (Sus scrofa domesticaL.) manure applied preplant or post‐emergence (six‐to‐eight leaf stage), at 152 kg N ha‐1, 39 kg P ha‐1, and 112 kg K ha‐1. The plots were rototilled (7 cm depth) in spring to incorporate fertilizer and preplant hog manure, and fall chisel‐plowed (15 cm depth) to incorporate chopped corn residues. They were arranged in a completely randomized plot design. Flow volumes and nutrient levels in runoff and drainage waters were monitored year round but occurred mainly during the snowmelt (March 25‐April 9), and post.snowmelt (April 10‐May 13) periods. Of the total amount of water lost during snowmelt, 90 percent was in runoff, while 92 percent occurred as drainage in the post‐snowmelt period. Sixty‐five percent of the total annual volume of water lost was lost during these two periods as runoff and drainage. Treatments did not affect the annual snowmelt or post‐snowmelt N and P loads. Total annual loads averaged 8.0 kg TKN ha‐1, 1.8 kg NH4‐N ha‐1, 43 kg NO3‐N ha‐1, 0.4 kg TP ha‐1, and 0.15 kg PO4‐P ha‐1. Spring (snowmelt and ost‐snowmelt) runoff and drainage loads averaged 2.9 kg TKN ha‐1, 1.2 kg NH4‐N ha‐1, 18 kg NO3‐N ha‐1, 0.25 kg TP ha‐1, and 0.04 kg PO4‐P ha‐1, which were 40 percent to 70 percent of the yearly nutrient loads. Therefore, the hog manure management systems examined were of no greater threat to the environment than mineral fertilizers. However, spring N and P losses do represent an important part of the annual nutrient loss budget, even with conservation practices.
STATISTICAL CONSIDERATIONS ON THE RANDOMNESS OF ANNUAL MAXIMUM DAILY RAINFALL1
Authors: Lisi Francesco , Villi Vigilio
Published: June 2007

ABSTRACT: Annual maximum daily rainfall data from nine stations throughout the southern slopes of the Eastern Italian Alps with record length of 67–68 years have been analyzed with the aim of verifying if their internal structure justifies the assumption of independence and identical distribution, or the “White noise hypothesis.” The approach is to consider the hypothesis H0 of white noise as the intersection of several sub‐hypotheses, each concerning one of the characteristics of a white noise process. To this end the nine series were subjected to various statistical tests regarding randomness, independence, change‐points, and predictability. The results are examined first individually and then globally. They indicate that in eight of the nine considered time series the “white noise hypothesis” was rejected.
WATER LEVEL MANAGEMENT OPPORTUNITIES FOR ECOLOGICAL BENEFIT, POOL 5 MISSISSIPPI RWER1
Authors: Woltemade Christopher J.
Published: June 2007

ABSTRACT: This paper examines the potential to manage Mississippi River water levels for ecological benefits. The study focuses on the Weaver Bottoms, a 4,000 acre backwater marsh in southeastern Minnesota (Pool 5) highly valued for fish and wildlife habitat. The Weaver Bottoms has suffered increasing loss of aquatic vegetation and associated habitat degradation since the 1960s, largely due to persistent high water, sedimentation, wave re‐suspension of sediments, and poor light penetration. In other reaches of the Mississippi River, water level reductions exposing backwater sediments have produced strong vegetative responses due to subaerial exposure of seeds and sediment compaction. Water level management scenarios for Pool 5 were developed using the HEC‐2 water surface profile model. Results indicate that in many years it would be possible to reduce water levels sufficiently to expose much of the Weaver Bottoms, generating a substantial vegetative response. Additional benefits could be expected since both sediment compaction and increased vegetation would reduce re‐suspension of sediments. Shifting management priorities to improve habitat would temporarily impact many river users, including both commercial and recreational boaters. Water level reductions must be coordinated with their needs.
POLLUTANT LOADING CAPACITY FOR THE BLACK RWER, CHEHALIS RWER SYSTEM, WASHINGTON1
Authors: Pickett Paul J.
Published: June 2007

ABSTRACT: The Black River, a tributary of the Chehalis River in western Washington State, has a history of widespread low dissolved oxygen (DO), anoxia in some locations, and fish kills. As part of a Total Maximum Daily Load (TMDL) study, environmental data were collected during two summer dry seasons and simulations were conducted with the WASP5 model to assess the effect of biochemical oxygen demand (BOD), ammonia, and nutrient loads on DO in the Black River. DO levels were below the State water quality regulatory criterion of 8.0 mg/L in almost all locations during the study. The slow middle reach of the river showed stratified conditions, with anoxia in some of the deepest pools. Based on model simulations, DO was found to still fall below the 8.0 mg/L criterion in the entire mainstem under “natural” conditions, and eutrophication was identified as a potential problem in the middle reach. A TMDL was proposed for BOD and ammonia that would prevent significant degradation of DO in the Black River. To prevent eutrophic conditions in the Black River, a TMDL for total phosphorus was proposed that establishes a protective criterion of 0.05 mg/L for the middle river during the dry low‐flow season.
VALUE OF WOODY RWER CORRIDORS IN LEVEE PROTECTION ALONG THE MISSOURI RWER IN 19931
Authors: Dwyer John P , Wallace Douglas , Larsen David R.
Published: June 2007

ABSTRACT:Following the Midwest flood of 1993, a study was initiated along a 39‐mile segment of the Missouri River to determine if there was an association between woody corridors and levee stability. A systematic sample of levee failures revealed that primary levees which did not fail had a significantly wider woody corridor than failed levees. Analysis of the total inventory of failed levees revealed that as the width of the woody corridor decreased, the length of the levee failure increased. Number of levee failures and their severity of damage could be reduced if woody corridors were at least 300 feet wide.
HYDROLOGY OF A DRAINED FORESTED POCOSIN WATERSHED1
Authors: Amatya D. M. , Skaggs R. W. , Gregory J. D. , Herrmann R. B.
Published: June 2007

ABSTRACT: In order to assess the effects. of silvicultural and drainage practices on water quality it is necessary to understand their impacts on hydrology. The hydrology of a 340 ha artificially drained forested watershed in eastern North Carolina was studied for a five‐year period (1988–92). Effects of soils, beds and changes in vegetation on water table depth, evapotranspiration (ET) and drainage outflows were analyzed. Total annual outflows from the watershed varied from 29 percent of the rainfall during the driest year (1990) when mostly mature trees were present to as much as 53 percent during a year of normal rainfall (1992) after about a third of the trees were harvested. Annual ET from the watershed, calculated as the difference between annual rainfall and outflow, varied from 76 percent of the calculated potential ET for a dry year to as much as 99 percent for a wet year. Average estimated ET was 58 percent of rainfall for the five‐year period. Flow rates per unit area were consistently higher from a smaller harvested block (Block B ‐ 82 ha) of the watershed than from the watershed as a whole. This is likely due to time lags, as drainage water flows through the ditch‐canal network in the watershed, and to timber harvesting of the smaller gaged block.
EFFECTS OF ARTIFICIAL RECHARGE ON GROUND WATER QUALITY AND AQUIFER STORAGE RECOVERY1
Authors: Ma Li , Spalding Roy F
Published: June 2007

ABSTRACT: Ground water nitrate contamination and water level decline are common concern in Nebraska. Effects of artificial recharge on ground water quality and aquifer storage recovery (ASR) were studied with spreading basins constructed in the highly agricultural region of the Central Platte, Nebraska. A total of 1.10 million m3 of Platte River water recharged the aquifer through 5000 m2 of the recharge basins during 1992, 1993, and 1994. This is equivalent to the quantity needed to completely displace the ground water beneath 34 ha of the local primary aquifer with 13 m thickness and 0.25 porosity. Successful NO3‐N remediation was documented beneath and downgradient of the recharge basins, where NO3‐N declined from 20 to 2 mg L‐1. Ground water atrazine concentrations at the site decreased from 2 to 0.2 mg L‐1 due to recharge. Both NO3‐N and atrazine contamination dramatically improved from concentrations exceeding the maximum contaminant levels to those of drinking water quality. The water table at the site rose rapidly in response to recharge during the early stage then leveled off as infiltration rates declined. At the end of the 1992 recharge season, the water table 12 m downgradient from the basins was elevated 1.36 m above the preproject level; however, at the end of the 1993 recharge season, any increase in the water table from artificial recharge was masked by extremely slow infiltration rates and heavy recharge from precipitation from the wettest growing season in over 100 years. The water table rose 1.37 m during the 1994 recharge season. Resultant ground water quality and ASR improvement from the artificial recharge were measured at 1000 m downgradient and 600 m upgradient from the recharge basins. Constant infiltration rates were not sustained in any of the three years, and rates always decreased with time presumably because of clogging. Scraping the basin floor increased infiltration rates. Using a pulsed recharge to create dry and wet cycles and maintaining low standing water heads in the basins appeared to reduce microbial growth, and therefore enhanced infiltration.
NONPOINT SOURCE DISCHARGES OF NUTRIENTS FROM PIEDMONT WATERSHEDS OF CHESAPEAKE BAY1
Authors: Jordan Thomas E. , Correll David L. , Weller Donald E.
Published: June 2007

ABSTRACT: We measured annual discharges of water, sediments, and nutrients from 10 watersheds with differing proportions of agricultural lands in the Piedmont physiographic province of the Chesapeake Bay drainage. Flow‐weighted mean concentrations of total N, nitrate, and dissolved silicate in watershed discharges were correlated with the proportion of cropland in the watershed. In contrast, concentrations of P species did not correlate with cropland. Organic P and C correlated with the concentration of suspended particles, which differed among watersheds. Thus, the ratio of N:P:Si in discharges differed greatly among watersheds, potentially affecting N, P or Si limitation of phytoplankton growth in the receiving waters. Simple regression models of N discharge versus the percentage of cropland suggest that croplands discharge 29–42 kg N ha‐1 yr‐1 and other lands discharge 1.2–5.8 kg N ha‐1 yr‐1. We estimated net anthropogenic input of N to croplands and other lands using county level data on agriculture and N deposition from the atmosphere. For most of the study watersheds, N discharge amounted to less than half of the net anthropogenic N.
A SEDIMENT RESUSPENSION AND WATER QUALITY MODEL OF LAKE OKEECHOBEE1
Authors: James R. Thomas. , Martin James , Wool Tim , Wang P F
Published: June 2007

ABSTRACT: The influence of sediment resuspension on the water quality of shallow lakes is well documented. However, a search of the literature reveals no deterministic mass‐balance eutrophication models that explicitly include resuspension. We modified the Lake Okeechobee water quality model ‐ which uses the Water Analysis Simulation Package (WASP) to simulate algal dynamics and phosphorus, nitrogen, and oxygen cycles ‐ to include inorganic suspend. ed solids and algorithms that: (1) define changes in depth with changes in volume; (2) compute sediment resuspension based on bottom shear stress; (3) compute partition coefficients for ammonia and ortho‐phosphorus to solids; and (4) relate light attenuation to solids concentrations. The model calibration and validation were successful with the exception of dissolved inorganic nitrogen species which did not correspond well to observed data in the validation phase. This could be attributed to an inaccurate formulation of algal nitrogen preference and/or the absence of nitrogen fixation in the model. The model correctly predicted that the lake is light‐limited from resuspended solids, and algae are primarily nitrogen limited. The model simulation suggested that biological fluxes greatly exceed external loads of dissolved nutrients; and sediment‐water interactions of organic nitrogen and phosphorus far exceed external loads. A sensitivity analysis demonstrated that parameters affecting resuspension, settling, sediment nutrient and solids concentrations, mineralization, algal productivity, and algal stoichiometry are factors requiring further study to improve our understanding of the Lake Okeechobee ecosystem.
SURFACE WATER QUALITY IMPACTS OF TILLAGE PRACTICES UNDER LIQUID SWINE MANIJRE APPLICATION1
Authors: Gupta R. K. , Rudra R. P. , Dickinson W. T. , Wall G. J.
Published: June 2007

ABSTRACT: Field studies were conducted to investigate the effects of tillage practices on the saturated hydraulic conductivity, and quantity and quality of surface runoff water resulting from the application of the liquid swine manure as a fertilizer. As part of the study, infiltration experiments were conducted on silt‐loam soil with no‐tillage (NT) and disk tillage (DT) practices. Liquid swine manure was applied on test plots, and the rainfall was applied by the portable rainfall simulator. The infiltration data was analyzed for the saturated hydraulic conductivity (K8) and runoff volume determinations. The surface runoff water was analyzed for total N, total P, ammonia, and nitrate concentration determinations. The study indicated that the tillage had significant effects on Ks, and quantity and quality of runoff water. The Ks values of the NT plots were found to vary from 0.693 to 1.734 mm/min, with a mean of 1.494 mm/min, while they varied from 1.056 to 2.543 mm/min, with a mean of 2231 mm/mm in the DT plots. The total N, total P, ammonium nitrogen and nitrate nitrogen concentrations were lower in runoff generated from DT plots, compared to that from the NT plots. The chemical concentration levels were significantly different in runoff waters collected one‐day after manure application than in those collected 40‐days after the manure application. Study suggested that the DT practice must be preferred over the NT practice if liquid swine manure is used as the fertilizer. The study is further continued to assess the long‐term impacts of swine manure application and tillage on the quantity and quality of surface runoff water.
EFFECTS OF BASIN‐SCALE TIMBER HARVEST ON WATER YIELD AND PEAK STREAMFLOW1
Authors: Burton Timothy A.
Published: June 2007

ABSTRACT:Streamflow changes resulting from clearcut harvest of lodgepole pine (Pinus contorta) on a 2145 hectare drainage basin are evaluated by the paired watershed technique. Thirty years of continuous daily streamflow records were used in the analysis, including 10 pre‐harvest and 20 post‐harvest years of data. Regression analysis was used to estimate the effects of timber harvest on annual water yield and annual peak discharge. Removal of 14 million board feet of lodgepole pine (Pinus contorta) from about 526 hectares (25 percent of the basin) produced an average of 14.7 cm additional water yield per year, or an increase of 52 percent. Mean annual daily maximum discharge also increased by 1.6 cubic meters per second or 66 percent. Increases occurred primarily during the period of May through August with little or no change in wintertime streamflows. Results suggest that clearcutting conifers in relatively large watersheds (> 2000 ha) may produce significant increases in water yield and flooding. Implications of altered streamflow regimes are important for assessing the future ecological integrity of stream ecosystems subject to large‐scale timber harvest and other disturbances that remove a substantial proportion of the forest cover.
ASSESSING STREAM CHANNEL STABILITY THRESHOLDS USING FLOW COMPETENCE ESTIMATES AT BANKFULL STAGE1
Authors: Olsen D. S. , Whitaker A. C. , Potts D. F.
Published: June 2007

ABSTRACT: Stream channel stability is affected by peak flows rather than average annual water yield. Timber harvesting and other land management activities that contribute to soil compaction, vegetation removal, or increased drainage density can increase peak discharges and decrease the recurrence interval of bankfull discharges. Increased peak discharges can cause more frequent movement of large streambed materials, leading to more rapid stream channel change or instability. This study proposes a relationship between increased discharge and channel stability, and presents a methodology that can be used to evaluate stream channel stability thresholds on a stream reach basis. Detailed surveys of the channel cross section, water surface slope, streambed particle size distribution, and field identification of bankfull stage are used to estimate existing bankfull flow conditions. These site specific stream channel characteristics are used in bed load movement formulae to predict critical flow conditions for entrainment of coarse bed material (D84 size fraction). The “relative bed stability” index, defined as the ratio of critical flow condition to the existing condition at bankfull discharge, can predict whether increased peak discharges will exceed stream channel thresholds.
INTERACTIONS BETWEEN GROUND WATER AND SURFACE WATER IN THE SUWANNEE RIVER BASIN, FLORIDA1
Authors: Katz Brian G. , DeHan Rodney S. , Hirten Joshua J. , Catches John S.
Published: June 2007

ABSTRACT: Ground water and surface water constitute a single dynamic system in most parts of the Suwannee River basin due to the presence of karst features that facilitate the interaction between the surface and subsurface. Low radon‐222 concentrations (below background levels) and enriched amounts of oxygen‐18 and deuterium in ground water indicate mixing with surface water in parts of the basin. Comparison of surface water and regional ground water flow patterns indicate that boundaries for ground water basins typically do not coincide with surface water drainage subbasins. There are several areas in the basin where ground water flow that originates outside of the Suwannee River basin crosses surface water basin boundaries during both low‐flow and high‐flow conditions. In a study area adjacent to the Suwannee River that consists predominantly of agricultural land use, 18 wells tapping the Upper Floridan aquifer and 7 springs were sampled three times during 1990 through 1994 for major dissolved inorganic constituents, trace elements, and nutrients. During a period of above normal rainfall that resulted in high river stage and high ground water levels in 1991, the combination of increased amounts of dissolved organic carbon and decreased levels of dissolved oxygen in ground water created conditions favorable for the natural reduction of nitrate by denitrification reactions in the aquifer. As a result, less nitrate was discharged by ground water to the Suwannee River.
PREDICTIVE ASSESSMENT OF SEVERITY OF AGRICULTURAL DROUGHTS BASED ON AGRO‐CLIMATIC FACTORS1
Authors: Kumar V. , Panu U.
Published: June 2007

ABSTRACT: Past historical evidence indicates that droughts have had great impacts on human life. Drought (or scarcity of water) is assessed based on two key factors, namely, the estimated water demand, and the expected water supply. The formulation of these key factors for a region largely depends on the agro‐climatic and economic conditions. Consideration of one such key factor is the relationship between the crop yield and water deficit in the assessment and prediction of agricultural droughts. The varying nature of this relationship from crop to crop adds to the complexity of agricultural drought analysis. To overcome this difficulty in analyzing agricultural droughts of a region, it is adequate to consider and place emphasis on a single crop (i.e., an index crop) grown homogeneously over the major area of the region. From one year to another year, the pattern of water requirement during the growing season of an index crop is rather stationary, and the water supply in arid and semi‐arid area is mainly from seasonal random precipitation. In a region, grain yield of the index crop and, in turn, assessment of the severity of drought can reasonably be predicted as a function of the time of crop sowing and the distribution of rainfall, provided that temporal and spatial effects of other contributing factors (crop variety, soil fertility status, crop disease, pest control, cultivation practices etc.) on grain yield are considered to be uniformly distributed (i.e., stable).

A predictive method of assessing agricultural droughts in an arid area of western India is presented. The major crop (Pearl Millet) of this region is grown from. July through September. The formulation of the proposed predictive method inherently implies that the grain yield of the main crop is a reliable indicator of agricultural drought. In the development of this predictive relationship (i.e., a regression type model) a number of potential yet simple variables affecting the grain yield in the region were investigated. The soil moisture index, although generally considered significant compared to the simple variables, has been found to account for insignificant variation in the grain yield. Results of our investigations suggest that it would be advisable to exclude the soil moisture index variable from the model. The proposed regression model can be used in the prediction of grain yield of the main crop several months ahead of crop harvesting operations and, in turn, the assessment of agricultural drought severity as mild, moderate, or severe. Such an assessment is expected to be helpful to planners for arranging appropriate measures to effectively combat agricultural drought situations.