John Borrelli

Wind Profile: Estimation of Displacement Height and Aerodynamic Roughness

ABSTRACT KEY parameters for describing the wind velocity profile are displacement height, D, and aerodynamic roughness, Z^. Both D and Z^ appear to be independent of wind velocity but dependent on surface characteristics. A procedure was developed to predict D and Zo from the geometry and fraction of cover of rigid surface roughness elements. The procedure was verified with three independent data sets. One data set obtained from several sources in the literature was used to estimate an unknown coefficient in the developed equations. An R^ of 0.92 and a significance level of a = 0.001 was obtained. The other two data sets fit the developed equations without further calibration and gave very high R^ and significance levels. Roughness elements ranged in size from sand grains to trees 20 m in height. Because of the excellent fit with independent data sets and the wide range in roughness height, the prediction procedure appears to be general.

Energy requirements of two tillage systems for irrigated sugarbeets, dry beans and corn.

ABSTRACT Achisel-based tillage system was compared with a moldboard plow-based tillage system for irrigated sugarbeets, dry beans and corn. Speed, travel reduction, and time, power, energy and fuel requirements were measured for each field operation for both tillage systems. Plant populations and yields were also sampled for the two years of study. The chisel-based system produced equal yields with approximately forty percent less energy, fuel and time for preplant tillage operations...

Wind Barriers: A Reevaluation of Height, Spacing, and Porosity

ABSTRACT Wind barriers are an important method to control soil erosion by wind. A review of the literature revealed that the equation currently in use to predict length of protection is not precise and does not satisfy known boundary conditions. Various data sets were studied and an alternative equation was formulated that both matches the published data and correctly fits the boundary conditions. This equation also included the variable of barrier porosity. The new equation was verified to fit published measurements with an R^ of 0.97 and was highly significnt (a = 0.001). A check was also made with data for a snow fence that were independent of the data used for calibration. For this data set, the R^ was 0.703, which was significant (a = 0.001). It was concluded that the new equation was an improvement over the equation currently in use.

Furrow Firming for Control of Irrigation Advance Rates

ABSTRACT Afurrowing-compacting unit was designed and built to reduce water intake during irrigation. The unit reshapes and compacts the furrow as well as clears no-till furrows of previous crop residue. Field tests indicate that the device is successful in improving irrigation water advance rates. On the soils tested, added weight on the firming unit was required to significantly improve the advance rate.

Elevation — A Bias Error in SCS Blaney Criddle ET Estimates

ABSTRACT ELEVATION adjustments for evapotranspiration estimates are investigated. Bluegrass and alfalfa data from throughout the Western states are used to determine an elevation adjustment for the SCS Blaney Criddle formula. Six to ten percent upward adjustment per 1000 m altitude increase above sea level is required for calculated evapotranspiration.

Urban Lawn Evapotranspiration—Measurement and Prediction

ABSTRACT THE Blaney-Criddle formula for estimating evapotranspiration is one of the most popular in the West and is the method generally used in court cases transfer-ring water rights from agricultural to municipal usages. Past application of the formula to lawn grasses has required using the formula based on information from agricultural surroundings. This paper presents a calibra-tion of the Blaney-Criddle formula based on measure-ments of evapotranspiration rates directly from urban lawns.