ARS | Publication request: Raindrop Characteristics in the Pacific Northwest

Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: May 19, 2009
Publication Date: June 21, 2009
Repository URL: http://hdl.handle.net/10113/40798
Citation: McCool, D.K., Williams, J.D., Morse, J.R. 2009. Raindrop Characteristics in the Pacific Northwest. ASABE Annual International Meeting. ASABE Paper No.097441. Reno, NV. June 21-24. Pp. 19.

Interpretive Summary: The U.S. Pacific Northwest, influenced by maritime air masses for most of the year, is generally characterized by long-duration low-intensity rain storms. The drop-size characteristics of such low-intensity storms are rarely studied. We investigated natural rain drop sizes in southeastern Washington near Pullman and in the Willamette Valley of western Oregon near Corvallis. Data was obtained from a number of storms by collecting drop splashes on Ozalid paper. The distribution of drop sizes, intensity, and total calculated kinetic energy of these storms are presented and compared with data and relationships from studies in the eastern U.S. This data will be used by ARS and University scientists for rainfall simulator design to study infiltration and erosion on cropland, rangeland, construction sites and other disturbed areas, as well as for improving databases for applying erosion models to areas with low-intensity rainfall. The NRCS and other entities have here-to-fore relied on extrapolation of rainfall characteristics from higher precipitation regions when applying hydrologic and erosion models to areas with low-intensity rainfall for agricultural and engineering planning purposes. This will reduce uncertainties in modeling and design and may reduce engineering project costs.

Technical Abstract: The U.S. Pacific Northwest, influenced by maritime air masses for most of the year, generally exhibits low rainfall intensities. The drop-size characteristics of such low-intensity storms are rarely studied. An investigation of natural drop sizes and their distribution was conducted at the Palouse Conservation Field Station in southeastern Washington near Pullman and in the Willamette Valley near Corvallis. Data was collected from a number of storms by Ozalid paper technique. The distribution of drop sizes, intensity, and total calculated energy of these storms are presented and compared with data and relationships from studies in other areas of the U.S. This data has implications for rainfall simulator design and application of erosion models in areas with low-intensity rainfall that here-to-fore have relied on extrapolation of rainfall characteristics from higher precipitation areas for driving hydrologic and erosion models.