Underdrain Tube Wall, Perforation Design and OBPA to Minimize Bio-Chemical Clogging
Bio-chemical clogging of underdrains has been most frequently associated with iron deposits (ochre). The underlying sticking agents have been a variety of bacteria and their exudates commonly...
Atrazine in Subsurface Drain Water in Southern Louisiana
Atrazine was applied preemergent to corn on subsurface drained and undrained plots. Atrazine soil concentration and concentration and loss in drain water were determined for 243 days after...
Pesticide and Nitrate Movement Under Conservation and Conventional Tilled Plots
Carbofuran, alachlor, atrazine, nitrate and bromide (a tracer) were applied to plots with conventional and conservation tillage. During the early part of the growing season the conservation...
Sorption and Transport of Aldicarb Through the Vadose Zone
The literature was reviewed regarding the sorption and transport of a nonionic organic pesticide aldicarb, an extremely toxic and relatively water soluble carbamate insecticide that has...
Use Requirements for Bowen Ratio and Eddy Correlation Determination of Evapotranspiration
Reduced costs and complexity are encouraging more operational use of eddy correlation (EC) and energy balance Bowen ratio (EBBR) instrumentation for estimating evapotranspiration. Often...
Theory and Operation of French Energy Balance, Bowen Ratio and Micro-Meteorology Instrumentation
The Penman formula for potential evapotranspiration (ETp) and the Energy Balance Method for actual evapotranspiration (ETr) provide information on evapotranspiration rates. Examination...
A Portable Bowen Ratio System for ET Measurements
The AZET system developed at the University of Arizona is designed to measure evapotranspiration (ET) in arid zone environments, using the Bowen ratio model. The system consists of a set...
Ultrasonic Flow Meter Testing
Six ultrasonic flow meters were tested in a hydraulics laboratory. Accuracies better than 2% were obtained with two transit-time meters on 14 inch diameter steel tubing. Poorer accuracies...
Irrigation Scheduling Using Voice Synthesis, the Next Logical Step
An irrigation management program sponsored by the Raft River Electric Cooperative in Malta, Idaho, provided directly measured soil moisture data to selected irrigators each week during...
Riverbank Instability Due to Bed Degradation
Degradation lowers the bed of an alluvial channel over a long reach. This has the effect of increasing the bank heights and angles, which decreases the stability of the banks with respect...
Hydraulic Design for La Quinta Stormwater Project
An upstream detention basin was designed to trap debris and attenuate flows into Bear Creek Channel. The high velocity supercritical flow made a one side bank protection design for the...
The USDA Water Erosion Prediction Project
New generation water erosion prediction technology is being developed by the USDA Water Erosion Prediction Project (WEPP). The new technology is expected to replace the Universal Soil...
Environmental Degradation of Spawning Gravels in the Tucannon River
The important relationship between upstream soil and water conservation measures and salmonid habitat conditions in the Pacific Northwest is illustrated by way of computer simulations...
Water Quality Modeling Using a Small Watershed Model (SWAM)
The Small Watershed Model (SWAM) is a state-of-the-art model that simulates the movement of water, sediment, and chemicals through a small, mixed-land-use watershed. It was developed to...
Analytical Studies of the Schoharie Bridge Failure
Analytical studies consisted of geomorphic, hydrologic, hydraulic, and erosion analyses including mathematical modeling with HEC-1 and WSPRO, the new FHWA water-surface profile model....
Reliability of Compacted Soil Liners
Determination of transport times of contaminants through a soil liner is hindered by the inherent spatial variability of the hydraulic conductivity of compacted soil. The existence of...
Estimation of Uplift Pressure in Cracks in Concrete Gravity Dams
This paper presents an analytical solution to predict uplift pressures in cracks in concrete gravity dams. It is shown that drainage systems are effective in reducing such pressures....
Design and Performance of Earth Spillways
The U.S. Department of Agriculture's Soil Conservation Service has designed and administered construction of a large number of dams utilizing grassed earth-lined auxiliary...
Application of Reservoir Sedimentation Data to Problems of Environmental Management
Application of sediment delivery ratios and sediment routing procedures to sediment measurements provide an alternative approach to the prediction of localized average annual erosion rates....
New Methodology for Determining the Optimal Rehabilitation and Replacement of Water Distribution System Components
A methodology is presented for the determination of the optimal timing for the rehabilitation/replacement of water distribution system components in order to minimize costs. In this model...
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