Spraydrop Kinetic Energy from Irrigation Sprinklers

Abstract

Kinetic energy contained in water drops as they impact the soil surface affects soil erosion and infiltration processes. Bubenzer and Jones (1971) found that splash of several silt loam soils was approximately proportional to drop kinetic energy to the 1.5 power, and intensity to the 0.5 power. Kinnell (1982) found that, for sand, splash loss per drop varied with the square of the drop mass. Thompson and James (1985) found that the hydraulic resistance of the surface seal formed on a silt loam soil by impacting water drops increased with drop kinetic energy. Mohammed and Kohl (1987) found that infiltration rates on a loam soil decreased more rapidly as water was applied with increased kinetic energy per unit volume. Moldenhauer and Long (1964) found that infiltration rates decreased and soil loss increased as the energy in the applied water increased. Moldenhauer and Kemper (1969) noted how the shearing action of water drops removes soil particles from large clods, causing severe sealing and crusting in depressions on the soil surface. Kincaid et al. (1990) noted how reservoir tillage increases infiltration rates and surface storage initially, but gradually degrades in Article was submitted for publication in May 1995; reviewed and approved for publication by the Soil and Water Div. of ASAE in January 1996. Presented as ASAE Paper No. 93-2103.Trade names and company names are included for the benefit of the reader and do not imply any endorsement or preferential treatment of the product listed by the USDA-Agricultural Research Service.The authors is Dennis C. Kincaid, ASAE Member Engineer, Agricultural Engineer, USDA-Agricultural Research Service, 3793 N 3600 E, Kimberly, ID 83341; effectiveness as water drops impact and degrade the dikes and ridges. Crust formation due to drop impact is also a problem in seedling emergence of crops like sugar beets. These studies point out the importance drop sizes and drop energy on breaking down the soil surface aggregates. Although natural rainfall and crop cover can overshadow the sprinkler drop energy effects on a seasonal basis, in areas where crops are established primarily by irrigation, sprinkler drop energy can be important.Existing sprinkler irrigation technology does not allow us to directly control drop sizes, so therefore, it is important to know the drop characteristics of a variety of sprinkler types in order to make intelligent choices in sprinkler system design. Several articles have been published describing the drop size distributions of specific types of sprinklers (Kohl, 1974;Kohl and DeBoer, 1984;Solomon et al., 1985;Kohl and DeBoer, 1990). Unfortunately, these data were collected using several different types of measurement methods, and some of the data may not be comparable, particularly in the upper and lower ends of the drop size spectra.This article presents sprinkler drop energy calculations using a consistent set of drop size data collected by the laser-optical method (Kincaid et al.,1996). The objective was to determine the kinetic energy (volume ...

Controlling Sprinkler Irrigation Runoff, Erosion, and Phosphorus Loss With Straw and Polyacrylamide

“…Well water (EC = 0.73 dS m1 , pH = 7.2, and SAR = 1.7) was used at a nozzle pressure of 76 kPa, providing a median drop size of 1.2 mm diameter. Droplet energy striking the soil surface was about 25 J kg-1 , calculated as described by Kincaid (1996). This relatively high energy was necessary to achieve the desired water application rate of 80 mm h-1 .…”

Polymer and sprinkler droplet energy effects on sugar beet emergence, soil penetration resistance, and aggregate stability

“…The applied water had a droplet size distribution with a median volumetric drop diameter (d 50) of 0.9-1.0 mm and low to moderate droplet energy, 5-8 J kg -1 , as estimated from Kincaid (1996) and Kincaid et al (1996). We irrigated the pots on the second, ninth, and fourteenth day after planting (DAP), applying about 11 mm of water each day.…”

“…The depth of water applied at each irrigation was measured with catch cans. Each irrigation system produced sprinkler droplets with relatively high droplet energies of 15-16 J kg-1 , as estimated from Kincaid (1996).…”

“…Spray heads with typical flat, smooth deflector plates produced the 8-J kg-1 energy rate (range 7-9 J kg -1 ) with d50 of 0.7-0.8 mm and spinning, four-groove plates produced the 16-J kg-1 rate (range 15-19 J kg-1) with d50 of 3.3 mm. In southern Idaho with no wind, droplet energies of 10 J kg -1 or more are common for center pivots with single-nozzle, impact-type sprinklers (Kincaid, 1996). The lateral-move irrigation system applied 19 mm of water to the site at 8 and 22 DAP to form a crust on all plots.…”

Simulação das perdas de água por evaporação e arraste, no aspersor NY-7 (4,6 mm x 4,0 mm), em sistemas de aspersão convencional

“…Essas perdas obtidas experimentalmente no campo variam entre 2% e 40%, com muitos valores dentro do intervalo de 10%-20% (KINCAID, 1996;KINCAID et al, 1996;KOHL et al, 1987;YAZAR, 1984), enquanto os valores obtidos de forma analítica ou por ensaios realizados em laboratório apresentam valores de 0,5% a 2% (KOHL et al, 1987).…”