Flood plain information study / Salinas National Monument / part 1 of 2 / Abo Unit / vicinity of Scholle, New Mexico

US Army Corps of Engineers

This flood study was prepared by the Albuquerque District U. S. Army Corps of Engineers (COE) for the U. S. Department of the Interior National Park Service (NPS) Southwest Regional Office. The study was authorized in a letter by Mr. Jack Nechels of the NPS dated August 12, 1982. The hydro logic and hydraulic computations were performed by Thomas Ryan, Hydraulic Engineer, of the Hydrologic Engineering Section, Planning Branch, Engineering and Planning Division, COE. The study addresses the requirements set forth by Executive Order 11988. Briefly, Section 2(a)(1) of E.O. 11988 (May 24, 1977) requires that, "Before taking an action (". . . Federally undertaken, financed or assisted construction and improvements," Section 1), each [federal] agency shall determine whether the proposed action will occur in a floodplain . . ." The term floodplain is defined "as a minimum, areas subject to inundation by a flood with a one percent chance of occuring in any year (i.e., "100-year or base flood")." The Salinas National Monument, located in Torrance and Socorro Counties of New Mexico, contains three separate units Abo, Quarai and Gran Quivira. This report is Part 1 of a two-part report and covers only the Abo Unit in Torrance County near Scholle, New Mexico. Part 2 of this report will be on the Quarai Unit in Torrance County near Punta de Agua, New Mexico. The Gran Quivira Unit in Socorro County near Gran Quivira, New Mexico, was not requested under this contract and will not be presented. Mr. Nechels' previously mentioned letter requested the "2-, 5-, 10- , 50-, 100-, 500- year frequency and Q maximum flood events for both the Abo and Quarai Units" (Salinas National Monument). No need was seen to evaluate the Gran Quivira Unit at present. 'Q maximum' was interpreted to mean probable maximum flood (PMF) peak. PMF is defined as the runoff from the theoretically greatest depth of precipitation for a given duration that is physically possible over a given size storm area at particular geographical location at a certain time of the year. It was agreed upon verbally between Mr. Garland (Gary) Moore, NPS, and Mr. Thomas Ryan, COE, that only the peak discharge for each event would be calculated and presented. Mapping for this study and report was provided by the NPS to the COE. The work maps are at a scale of 1 in. = 50 ft. with a contour interval of 1 ft. and are based on aerial photography exposed on September 29, 1978. The mapping was produced under a NPS contract to the Remote Sensing Division of the NPS located at the Bandelier West Building on the University of New Mexico Campus, Albuquerque, New Mexico. The datum i6 arbitrary and is in no way related to mean sea level. No attempt was made by the COE or the NPS or any other agency to reference the arbitrary datum to a national or state datum. The initial contracting officer for the NPS was Mr. Garland Moore.