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Title: EMBANKMENT OVERTOPPING AND RCC STEPPED SPILLWAY RESEARCH

Author
item Hunt, Sherry
item Hanson, Gregory
item Temple, Darrel
item Kadavy, Kem

Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: 6/15/2005
Publication Date: 7/17/2005
Citation: Hunt, S., Hanson, G.J., Temple, D.M., Kadavy, K.C. 2005. Embankment overtopping and RCC stepped spillway research. In: American Society of Agricultural Engineers Annual International Meeting, July 17-20, 2005, Tampa, Florida. Paper No. 05-2204. 2005 CDROM.

Interpretive Summary: The USDA-ARS Hydraulic Engineering Research (HERU) has provided research assistance to the USDA-Natural Resources Conservation Service, primarily for their Small Watershed Program and more specifically for the flood retarding structures that have been constructed with their assistance. Historically, research at the laboratory has included such topics as vegetated channels, trash racks, cantilever pipe outlets, and rock chutes among others. Today, many of the NRCS watershed structures are nearing the end of their planned service life, and HERU continues to work on issues related to the safe operation of these structures. The studies outlined in this document are primarily associated to the current and future research planned at the laboratory to address the upgrade of these structures to meet current dam safety standards. Planned and continuing research projects at HERU include allowable overtopping and embankment erosion due to overtopping (i.e. vegetal failure; concentrated flow; headcut migration; breach timing, formation, and widening; and embankment toe protection) and RCC stepped spillway design (i.e. converging chutes, stilling basin design, various step heights for optimizing energy dissipation). The tools and design guidelines developed from this research are expected to give conservationists and engineers knowledge in making sound engineering judgments in rehabilitation design of flood retarding structures.

Technical Abstract: For over 50 years, the NRCS has assisted in the construction of over 11,000 small watershed dams. These dams provide millions of dollars in benefits each year by providing flood control, wildlife habitat, recreation, irrigation and livestock water, and municipal and rural water supplies. While many of these dams continue to adequately provide these benefits, it is currently estimated that nearly half of the NRCS dams will surpass their planned service life in the next 10 years. For these structures to continue to function properly and safely, rehabilitation is required. If ignored, these dams could place life and property at risk. The ARS Hydraulic Engineering Research Unit (HERU) has partnered throughout its existence with the NRCS by assisting them with their research needs in flood control related areas including vegetated spillways, principal spillway inlets (i.e. trash racks) and outlets (i.e. riprap protection in plunge pools), and grade control structures (i.e. rock chutes). As NRCS watershed structures reach the end of their planned service life, HERU continues to work on issues related to their safe operation. The objective of this paper is to provide information on current and future research conducted at the ARS Hydraulic Laboratory. Current projects at HERU include research of allowable overtopping and embankment erosion due to overtopping (i.e. vegetal failure, concentrated flow, headcut migration, and breach timing, formation, and widening) and RCC stepped spillway design (i.e. converging chutes, stilling basin design, various step heights for optimizing energy dissipation). This research is being conducted in order to give conservationists and engineers additional tools in rehabilitation design.