| 词条 | Spencer Dam |
| 释义 |
| name = Spencer Dam | name_official = | image = Spencer Dam (Nebraska) 1.JPG | image_size = | image_caption = Spencer Dam in 2010 | image_alt = | location_map = Nebraska | location_map_size = | location_map_caption = Location of Spencer Dam in Nebraska | location_map_alt = | coordinates = | country = United States | location = Near Spencer, Nebraska | purpose = Hydroelectric | status = Failed | construction_began = | opening = 1927 | demolished = March 14, 2019 | cost = | builder = | designed_by = | owner = NPPD | operator = | dam_type = Buttressed concrete gravity and embankment | dam_crosses = Niobrara River | dam_height_foundation = {{convert|26|ft|m|abbr=on}}[1] | dam_height_thalweg = | dam_length = {{convert|3698|ft|m|abbr=on}}[1] | dam_elevation_crest = | dam_width_crest = | dam_width_base = | dam_volume = | spillway_count = | spillway_type = | spillway_length = | spillway_capacity = | spillway_volumetric_flow_rate = | spillway_type2 = | spillway_length2 = | spillway_capacity2 = | spillway_volumetric_flow_rate2 = | spillway_type3 = | spillway_length3 = | spillway_capacity3 = | spillway_volumetric_flow_rate3 = | res_name = | res_capacity_total = {{convert|16847|acre feet|m3|abbr=on}} (silted)[1] | res_capacity_active = | res_capacity_inactive = | res_catchment = | res_surface = {{convert|1200|acre|ha|abbr=on}}[4] | res_max_length = | res_max_width = | res_max_depth = | res_elevation = | res_tidal_range = | plant_name = Power station | plant_coordinates = | plant_operator = | plant_commission = 1927 | plant_decommission = 2017 | plant_type = Conventional | plant_hydraulic_head = | plant_turbines = 1x 2000 KW 1x 1300 KW | plant_pumpgenerators = | plant_pumps = | plant_capacity = 3300 KW | plant_capacity_factor = | plant_efficiency = | plant_storage_hours = | plant_annual_gen = 14,848,000 KWh[5] | plant_annual_gen_year = 1996 | website = | extra = }}Spencer Dam was a run of the river hydroelectric dam on the Niobrara River in Boyd County and Holt County, Nebraska, about {{convert|5|mi|km}} southeast of Spencer. The dam was operated by the Nebraska Public Power District (NPPD). Heavy precipitation during the March 2019 North American blizzard led to a failure of the dam in the early morning of 14 March, causing heavy flooding downstream.[1] HistoryInitial construction was completed in 1927, at a site located {{convert|39|mi|km}} upstream of the Niobrara's confluence with the Missouri River.[2] The dam was originally {{convert|3698|ft|m}} long and {{convert|26|ft|m}} high, constructed in several sections.[1] The powerhouse was located on the north bank of the river, consisting of two Westinghouse generators with capacities of 2000 and 1300 kilowatts.[4] The spillway consisted of four tainter gates and five stoplog gates to the south of the powerhouse. The combined length of the powerhouse and spillway was {{convert|404|ft|m}}; the rest of the dam was an earth embankment extending to the south side of the Niobrara valley.[4] The dam originally formed a reservoir with a capacity of {{convert|16847|acre feet|m3}},[2] a normal storage of {{convert|5306|acre feet|m3}},[1] and a surface area of {{convert|1200|acre|ha}}.[3] In 1935 the dam was partially breached after an ice jam broke upstream. It was reconstructed in 1940.[2] Both after its initial construction and after rebuilding in 1940, the dam was filled with sediment within a few years.[4] Although this did not affect hydropower generation since the dam was operated to match the river flow,[1] twice-annual sluicing had been conducted since 1948 to clear sediment away from the power intakes.[3] The dam gates were opened for about two weeks each year, allowing the river to flow through and wash accumulated sediment downstream.[3] Between 1975 and 1989, fish kills occurred in the Niobrara River that were attributed to sluicing activities. In response, engineers began draining the reservoir more slowly, which has worked in preventing further fish kills.[3] By 1985, Spencer Dam was the only active hydroelectric plant on the Niobrara River, after the upstream Cornell Dam ceased operation.[5] The NPPD had rights to {{convert|1400000|acre feet|m3}} of water per year for power generation. As of 2007, the average annual flow through the power plant was {{convert|874000|acre feet|m3}}.[2] In 2007, in regards to severe declines in the flow of the Niobrara River as a result of upstream irrigation, NPPD requested that the state of Nebraska make farmers pay as compensation for lost power generation. Several lawsuits were filed as a result, but as of May 2010 all had been decided in favor of NPPD, whose water rights are senior to the irrigators' rights.[2] In September 2015, NPPD announced that it would be decommissioning the Spencer hydropower plant in 2017 due to increasingly uneconomical cost of power generation at this site. The water rights would be sold for $9 million to the Nebraska Game and Parks Commission and five local natural resources districts to manage the river for agriculture, recreation and wildlife conservation. The dam was planned to remain in place with the gates permanently removed, allowing the river to flow freely through the site.[6] 2019 failureOn the early morning of March 14, 2019, the dam was breached after a major storm caused heavy rain, snowmelt and ice breakage to swell the Niobrara River. The earth embankment was washed out in two locations, while the spillway remained partially intact (though heavily damaged). A {{convert|11|ft|m|adj=on}} wall of water was released by the failure, as recorded by a U.S. Geological Survey stream gage moments before it was washed away.[7] The initial break destroyed a saloon and private residence below the dam and washed out part of U.S. Highway 281. The owner of the home was reported missing and presumed dead. In the town of Niobrara, dozens of buildings and the Mormon Canal Bridge carrying Nebraska Highway 12 were washed away. A water pipeline under the Niobrara River bed was destroyed, cutting off the supply for about 2,000 people in Boyd County.[7] The dam failure forced the evacuation of residents in low lying areas along the river.[8][9] Shortly after the dam burst, Knox County Sheriff Don Henery announced: "The Knox County Sheriff’s Office has been advised that the Spencer Dam has been compromised. We are trying to contact everyone along the Niobrara River to evacuate them. Please pass the word. Niobrara and Verdigre (Nebraska) Fire and Rescue are on stand-by."[28] As the floodwaters reached the Missouri River, the U.S. Army Corps of Engineers was forced to boost releases at Gavins Point Dam to {{convert|90000|cuft/s|m3/s}}, the highest level since 2011 and the second highest on record.[10] The Chief Standing Bear Memorial Bridge across the Missouri River below the Niobrara confluence was temporarily closed as the Nebraska approach flooded, but it reopened a few days later. NPPD later said that workers had attempted to open the dam's manually operated gates to release floodwater, but some were frozen shut by the cold weather and may have contributed to water overtopping the earthen embankment a short while later. In addition "truck-sized ice chunks" were reported to have hit the dam and also caused the destruction of the bridges downstream.[11] During an inspection in April 2018 the Nebraska Department of Natural Resources had warned that "deficiencies [in the dam] exist which could lead to dam failure during rare, extreme storm events."[12] Because the 2015 sale of the dam had been delayed until after its destruction, the damsite will no longer be sold to the state of Nebraska as originally planned. The remains of the dam are planned to be demolished, although NPPD will retain the water rights to the river.[12] References1. ^[https://twitter.com/NWSMBRFC/status/1106218689001676801 NWSMBRFC] tweet on 14 March 2019 with map of the flooding downriver to the Missouri River upon failure, by National Weather Service Missouri Basin River Forecast Center 2. ^1 2 3 4 5 {{cite web|url=https://outdoornebraska.gov/wp-content/uploads/2015/11/Niobrara_Econ_Agricultural_Study_Phase_Report_2010.pdf|title=The Extent and Value of Agricultural, Municipal and Industrial Water Use in the Niobrara Basin|publisher=Nebraska Game and Parks Commission|author=Shultz, Steven|date=2010-12-07|accessdate=2019-03-18}} 3. ^1 2 3 4 5 6 {{cite journal|url=https://pdfs.semanticscholar.org/4c1b/b09277c26b873f01cdad9946147255bd6cd8.pdf|title=Environmental Impacts in the Vicinity of Spencer Hydropower Dam During Sluicing Activities in the Niobrara River, Nebraska|author=Gutzmer, Michael P. |author2=King, Justin W. |author3=Overhue, David P.|journal=Transactions of the Nebraska Academy of Sciences and Affiliated Societies|volume=81|number=1|year=1996}} 4. ^{{cite book|title=River Flow 2016: Proceedings of the International Conference on Fluvial Hydraulics, St. Louis, USA|pages=1448–1449|year=2016|editor=Constantinescu, George |editor2=Garcia, Marcelo |editor3=Hanes, Dan|publisher=CRC Press|isbn=1-31564-447-9}} 5. ^1 2 3 4 5 6 {{cite web|url=ftp://ftp.dnr.nebraska.gov/Pub/data/NiobraraInstreamFlowApplications/2/Appendix%201%20-%20Niobrara%20River%20Background/Appendix%201%20-%20Niobrara%20River%20Background.pdf|title=Appendix 1: Niobrara River Background|publisher=Nebraska Department of Natural Resources|work=Niobrara River Instream Flow Documents|accessdate=2019-03-18}} 6. ^{{cite news|url=https://www.omaha.com/news/nebraska/nppd-to-shut-down-spencer-dam-hydropower-plant-give-up/article_9d00c0e6-57d6-11e5-86d6-1ffdfd8a6188.html|title=NPPD to shut down Spencer Dam hydropower plant, give up water rights on Niobrara River|author=Hendee, David|work=Omaha World-Herald|date=2015-09-11|accessdate=2019-03-18}} 7. ^1 {{cite news|url=https://journalstar.com/news/state-and-regional/nebraska/foot-wall-of-water-one-dam-breaks-three-counties-suffer/article_eaf487d7-acc0-53a8-8786-9eccb43942ed.html|title=11-foot wall of water: One dam breaks, three counties suffer|author=Salter, Peter|work=Lincoln Journal Star|date=2019-03-17|accessdate=2019-03-18}} 8. ^{{cite news|url=http://norfolkdailynews.com/news/spencer-dam-breaks-many-towns-evacuated/article_9fc2dbca-466b-11e9-a640-3321ff8787d3.html|title=Spencer dam breaks, many towns evacuated|work=Norfolk Daily News|author=Warneke, Kent |author2=Guenther, Jerry|date=2019-03-14|accessdate=2019-03-18}} 9. ^{{cite news|author=Hammel, Paul|title='I've never seen anything close to this': Rancher describes harrowing evacuation near collapsed Spencer Dam|work=Omaha World-Herald|date=2019-03-14|url=https://www.omaha.com/news/nebraska/i-ve-never-seen-anything-close-to-this-rancher-describes/article_5e95c9df-be59-5bf9-93f7-42aadd2e4718.html}} 10. ^1 {{cite news|title=Spencer Dam Break Causes Corps To Raise Gavins Point Dam Releases|author=Dockendorf, Randy|work=Yankton Daily Press & Dakotan|date=2019-03-14|url=https://www.yankton.net/community/article_f8637fcc-46cb-11e9-8d13-d388f1b32cac.html}} 11. ^{{cite news|url=https://www.enr.com/articles/46616-nebraska-flood-exposes-weak-points|title=Nebraska Flood Exposes Weak Points|author=Yoders, Jeff|date=2019-04-03|work=Engineering News-Record}} 12. ^1 {{cite news|url=https://www.omaha.com/news/nebraska/spencer-dam-s-collapse-raises-questions-about-what-went-wrong/article_a71ae921-0024-51d7-9414-78c29b568692.html|title=Spencer Dam's collapse raises questions about what went wrong with 92-year-old structure|author=Hammel, Paul|work=Omaha World-Herald|date=2019-03-22}} External links
4 : Buildings and structures in Nebraska|Dams in Nebraska|Geography of Boyd County, Nebraska|Dam failures in the United States |
| 随便看 |
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。