|History of the USDA-ARS Hydraulic Engineering Research Unit|
During the Dust Bowl era in the 1930's, conservation of our soil became a national focus. Conservationists began developing best management practices for soil conservation. One of those practices, vegetative waterways, led to the establishment of the USDA-Soil Conservation Service (SCS) Outdoor Hydraulic Laboratory near Spartanburg, South Carolina in 1936. The initial intent of the laboratory was to answer questions related to the proper design of grass-lined waterways. However in 1941, The laboratory was moved to its present location near Lake Carl Blackwell, approximately 7 miles west of Stillwater, Oklahoma where better facilities and research channels could be built. Under the direction of civil engineer William O. Ree, the Outdoor Hydraulic Laboratory was built which included various vegetated channels and five 20-inch siphons that have a capacity to draw water from Lake Carl Blackwell at a rate of 200 cubic feet per second. Now known as the Hydraulic Engineers Research Unit (HERU), it became part of the USDA-Agricultural Research Service (ARS) in 1953. Still under the direction of project supervisor William O. Ree, the early-day purpose of the laboratory was to study the hydraulics of grass-lined channels, including terrace outlet channels, farm reservoir emergency spillways, diversions, and meadow strips. Research later expanded to incorporate hydraulic structures, including trash guards for closed conduit spillway entrances, hood inlet pipe spillways, rock chutes, and box inlet drops. The ARS Saint Anthony Falls Laboratory in Minneapolis, Minnesota, also conducting research on hydraulic structures and was integrated into HERU in 1983. In addition to research related to hydraulic structures, significant advances were made in the area of watershed runoff measurement through the development of new flow measurement devices and calibration procedures. Advancements also continued on vegetated channels, concentrated flow erosion, and headcut erosion. Laboratory scientists have worked in cooperation with the USDA-Natural Resources Conservation Service (NRCS) (Formerly the SCS) since the laboratories inception. This cooperation has led to the development of Sites, Water Resource Site Analyses software used in design of watershed dams and spillways and the development of WinDAM (Windows Dam Analysis Modules) used in the evaluation of dams for breach potential and the prioritization of dams for rehabilitation. More recently, research has supported the rehabilitation efforts of the USDA Small Watershed Program through embankment overtopping and internal erosion research and the development of design criteria for overtopping protection like stepped spillways. Under Ree and his successor's leadership, the laboratory had gained national and international recognition as a significant contributor of sound design criteria for soil and water conservation structures and channels.
Grass-lined Channels for Waterways and spillways
The 1930's was a time of extreme erosion brought about by drought, poor farming techniques, and severe weather. It was during this time that the nation began to work on conservation programs. The earliest research at the hydraulic laboratory was conducted on grassed waterways. This research resulted in the 1946 publication, SCS-TP-61, handbook of Channel Design for Soil and Water Conservation. Over a half million miles of grassed waterways have been built around the world based upon this criteria. The laboratory was designated in 1990 as a Historic Landmark of Agricultural Engineering for its work in this area.
Riprap Design for Rock Chutes and Stilling Basins
Hydraulic laboratory engineers have devoted many hours of research to riprap protection to alleviate erosion. Design criteria had been devoloped by research engineers for size and placement of riprap downstream from submerged pipe outlets in dams and low-drop grade-control structures. Other research includes the design for rock chutes on steep slopes for channel stabilization, grade control, and embankment overtopping protection.
Flood control reservoirs temporarily store runoff water and a principle spillway is used to maintain the normal pool elevation behind a dam embankment. The principle spillway (an inlet tower connected to a pipe through the dam) allows water to be slowly released at a controlled rate to prevent flooding downstream. One of the problems experienced with these spillways is clogging with trash such as tree branches, leaves, and man-made materials. The cooperation of ARS and NRCS engineers working together resulted in the development of the stepped baffle trash rack to reduce this problem.
Auxiliary vegetated spillways convey extreme flood water flow around a dam embankment to the valley downstream. ARS, NRCS, and Kansas State University worked together using data from actual spillway flows and research conducted at the Hydraulics Laboratory to develop the Water Resource Site Analysis software (SITES). Engineers use this program for design performance and analysis of spillways for flood control dams to better protect the safety of the dam, and lives and property downstream.
Many of the nation's flood control dams that were built through USDA watershed programs are reaching the end of their planned design life span. Hydraulic Laboratory engineers are investigating limited overtopping of the dams and RCC Stepped Spillways as alternatives to raising the top of the dam for increased storage capacity, or widening spillways to obtain more flow capacity. Other rehabilitation issues are also being studied at the laboratory, such as earthen embankment failure processes and impacts.
The USDA-NRCS administers the USDA Small Watershed Program through the financial and technical assistance provided for the construction of more than 11,000 flood control dams across the nation. Oklahoma leads the nation with more than 2100 of those dams. The USDA-ARS continues to support the USDA Small Watershed Program through important hydraulic research.