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J.M. Fulford

Publications and source records attributed to J.M. Fulford.

10 recordsLinked to original sources
USGS2012

Field comparison of optical and clark cell dissolved-oxygen sensors

Three multi-parameter water-quality monitors equipped with either Clark cell type or optical type dissolved-oxygen sensors were deployed for 30 days in a brackish (salinity <10 parts per thousand) environment to determine the sensitivity of the sensors to biofouling. The dissolved-oxygen sensors compared periodically to a hand-held dissolved oxygen sensor, but were not serviced or cleaned during the deployment. One of the Clark cell sensors and the optical sensor performed similarly during the deployment. The remaining Clark cell sensor was not aged correctly prior to deployment and did not perform as well as the other sensors. All sensors experienced substantial biofouling that gradually degraded the accuracy of the dissolved-oxygen measurement during the last half of the deployment period. Copyright ASCE 2005.

Conference Paper↗
USGS2012

Radar stage uncertainty

The U.S. Geological Survey is investigating the performance of radars used for stage (or water-level) measurement. This paper presents a comparison of estimated uncertainties and data for radar water-level measurements with float, bubbler, and wire weight water-level measurements. The radar sensor was also temperature-tested in a laboratory. The uncertainty estimates indicate that radar measurements are more accurate than uncorrected pressure sensors at higher water stages, but are less accurate than pressure sensors at low stages. Field data at two sites indicate that radar sensors may have a small negative bias. Comparison of field radar measurements with wire weight measurements found that the radar tends to measure slightly lower values as stage increases. Copyright ASCE 2005.

Conference Paper↗
USGS2004

An intensity scale for riverine flooding

Recent advances in the availability and accuracy of multi-dimensional flow models, the advent of precise elevation data for floodplains (LIDAR), and geographical GIS allow the creation of hazard maps that more correctly reflect the varying levels of flood-damage risk across a floodplain when inundatecby floodwaters. Using intensity scales for wind damages, an equivalent water-damage flow intensity scale has been developed that ranges from 1 (minimal effects) to 10 (major damages to most structures). This flow intensity scale, FIS, is portrayed on a map as color-coded areas of increasing flow intensity. This should prove to be a valuable tool to assess relative risk to people and property in known flood-hazard areas.

Conference Paper↗
USGS2002

Model Performance of Water-Current Meters

The measurement of discharge in natural streams requires hydrographers to use accurate water-current meters that have consistent performance among meters of the same model. This paper presents the results of an investigation into the performance of four models of current meters - Price type-AA, Price pygmy, Marsh McBirney 2000 and Swoffer 2100. Tests for consistency and accuracy for six meters of each model are summarized. Variation of meter performance within a model is used as an indicator of consistency, and percent velocity error that is computed from a measured reference velocity is used as an indicator of meter accuracy. Velocities measured by each meter are also compared to the manufacturer's published or advertised accuracy limits. For the meters tested, the Price models werer found to be more accurate and consistent over the range of test velocities compared to the other models. The Marsh McBirney model usually measured within its accuracy specification. The Swoffer meters did not meet the stringent Swoffer accuracy limits for all the velocities tested.

Conference Paper↗
USGS1993

General implicit representation of hydraulic structures in numerical flow models

Effects of hydraulic structures (such as culverts, bridge openings, or gates) can be simulated in numerical surface-water-flow models. Generally the scale and dimension of the numerical model is insufficient to model flow through the structure directly. However, if for a particular hydraulic structure a unique relation exists among headwater elevation, tailwater elevation, and discharge through the structure, the effect of the structure can be introduced by enforcing the unique three-parameter relation among three dependent model variables: water-surface elevations immediately upstream and downstream of the structure and discharge through the structure. The three-parameter relation might be implemented through an equation or sets of equations specific to each particular structure. The technique described is more general, viewing the locus of points satisfying any unique three-parameter relation as a surface. The surface is described by a set of points with coordinates corresponding to the three parameters. Values and gradients required for implicit implementation of the unique three-parameter relation in a numerical flow model are interpolated from the surface. The technique described provides a general interface between numerical flow models and effects of any hydraulic structure characterized by a unique three-parameter relation.

Conference Paper↗
USGS1984

Evaporation from flowing channels

Stability‐dependent and Dalton‐type mass transfer formulas are determined from experimental evaporation data in ambient and heated channels and are shown to have similar performance in prediction of evaporation. The formulas developed are compared with those proposed by other investigators for lakes and flowing channels. The evaporation data were obtained from a heat‐budget analysis of two large outdoor channels, one of which received ambient‐temperature water from an adjacent reservoir while the other received an artificially‐heated discharge. Daily evaporation was calculated from bihourly values of water temperature and hourly values of meteorological variables for a 63‐day study period in the summer. The evaporation data were then used to derive mass transfer evaporation formulas for heated and ambient flowing channels.

Journal of Energy Engineering - ASCE↗