THE AFFECTS AND PREVENTION OF

FLOODS

x

Kyle Rosbrook

Maple Creek 2010 http://www.youtube.com/watch?v=R6TIG

Apo1Iw&feature=related Although this is an extreme example of a

flood, these are the effects that are quite possible

Many rivers flood every year, damaging property and leaving people virtually homeless

The Red River In any given year, the specific causes of

flooding along the Red River relate to a combination of hydrological factors, including wet ground conditions in the previous autumn, development of severe frost in late autumn, heavy snow fall particularly during the latter part of the winter, a late and sudden warming during the spring, and an above normal rainfall during the period of rapid snowmelt. Such factors are similar to those that cause flooding along the majority of rivers in Canada.

COURSE OF THE RED RIVER

In the 1950’s the Red River flooded, the river that is normally 152 m wide expanded to 64 km across.

It flooded 1036 km² 80 000 people were

evacuated from Winnipeg 13 000 homes were

damaged

Ice Jams

Red River flooding http://www.youtube.c

om/watch?v=16R6uL1bbIM&NR=1

Ice Jam Demolition http://www.youtube.c

om/watch?v=ZsUY-6SgXas

Ice Jams are also a major cause of flooding. When river water starts to flood and ice jams or river glaciers further north have jammed the flow, this caused waters to be restricted and start to move laterally.

Flood PlainsWHAT IS IT? WHY BUILD HERE?

Flood plains are made by a meander eroding sideways as it travels downstream. When a river breaks its banks and floods, it leaves behind layers of rock and mud. These gradually build up to create the floor of the flood plain. Floodplains generally contain unconsolidated sediments, often extending below the bed of the stream

Historically, many towns have been built on floodplain, where they are highly susceptible to flooding, for a number of reasons:

access to fresh water; the fertility of floodplain land for

farming; cheap transportation, via rivers

and railroads, which often followed rivers;

ease of development of flat land

However, this makes towns and cities very susceptible to flooding!!!!

Dikes The main purpose of an artificial levee is

to prevent flooding of the adjoining countryside; however, they also confine the flow of the river, resulting in higher and faster water flow. Levees can be along rivers for protection against high-floods.

Manitoba’s Flood Prevention

The Winnipeg Floodplain The floodplain that Winnipeg originally created

was 48 km wide to divert water around the city, and was recognized in 2008 as 1 of 16 engineering achievements that has shaped the world since biblical times

However, in 1997 it was put to the test, and avoided most damage, however the 1950’s flood was 40% larger than this flood

They invested an addition $665 million to make it better

This huge “ditch” can be seen by astronauts from outer space!!!!

Changing Floodplains The flooding of the New Orleans Hurricane

in 2005 is an example of a disaster made worse because of changes to a floodplain

The Mississippi was straightened and dredged to that it would flow quicker to the Gulf, however this prevented deposit of sediment and swampy forests to, so the spread of the force was no longer there

This essentially concentrated all the water to New Orleans, flooding and detroying much of the city

This essentially concentrated all the water to New Orleans, flooding and destroying much of the city