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|Fanshawe Dam & Reservoir|
The primary purpose of Fanshawe Dam and Reservoir is to assist in flood control efforts to reduce flood damage in the City of London. Throughout most of the year, the amount of water released from the reservoir is the same as the amount of water entering from upstream. During a flood, less water is released than comes into the reservoir, which results in the reservoir gradually filling up as the extra water is stored. After the flood passes, the stored water is gradually released. Although some flooding may still occur, the flood peaks (the highest flood levels) downstream may be reduced by up to 40% (see graph below).
Hydrology staff use information from several sources to operate Fanshawe Dam and to integrate operations of the three dams on the Thames. Computer models of floods, operating tables, weather data and water level information from above and below the dam enable staff to assess and respond to flood potential and initiate the municipalities flood warning systems, if necessary. Many factors affect the severity of flooding, such as snow pack (depth and water content), soil conditions (may be frozen or saturated), temperature (affects snow melt, evaporation and soil moisture) and plant cover (may intercept rainfall). The amount of rain and where it falls is also important. Although London may not receive much precipitation, snowmelt or rainfall in the northern part of the watershed could cause flooding in the city.
|Reservoir in normal (non-flood) operating conditions||Length||6.4 kilometres|
|Maximum width||0.8 km|
|Maximum depth||12.5 metres|
|Surface area||2.61 square km|
|Storage||12 billion litres|
|Surface elevation||262.1 metres above sea level (masl)|
|Drop in elevation to river surface||12.1 m|
|Reservoir in maximum possible flood conditions (these are projected maximum levels and have not been reached in a flood)||Length||12 km|
|Surface area||6.5 sq km|
|Storage||48 billion L|
|Highest possible surface elevation||271.3 masl|
|Highest recorded surface elevation||270.7 masl (March 1977)|
|Dam & Berm||Length of crest||625 m|
|Distance from crest to river bed||23.5 m|
|Distance from crest to bedrock||30.5 m|
|Bridge deck elevation||273.1 masl|
|Inspection tunnel elevation||246.3 masl|
|Size of sluice gates (6)||9.1 m2, 33.6 tonnes|
|Maximum total discharge capacity||3,200 cubic metres/second (cms)*|
|Typical summer discharge||4 cms|
|Maximum recorded discharge||654 cms (March 1963)|
* 1 cubic metre = 2 bathtubs; 100 cubic metres = in-ground pool
Did you know that . . .
Safety around Dams (MNR webpage)
This page was last
June 18, 2013.
Copyright © 2012 Upper Thames River Conservation Authority
1424 Clarke Road, London, Ontario, Canada N5V 5B9 tel: 519-451-2800 fax: 519-451-1188
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