Historic Flooding in the Mississippi Valley

  • Historic Flooding in the Mississippi Valley
    14.05.2011 14:37


    The Mississippi River has risen this year to levels not seen in decades, and extreme rainfall in April inundated the central US and Ohio Valley.

    Parts of the Ohio River Valley received as much as 20 inches of rain during the month, around half of their annual average precipitation. Illinois, Indiana, Kentucky, Ohio, West Virginia and Pennsylvania each had their wettest April since at least 1895.

    An average of 11.88 inches of precipitation fell across Kentucky, nearly three times its long-term average. This rainwater as well as the spring thaw of snow from the Appalachians have fed into the Mississippi River and have caused massive flooding upstream, the worst flooding in Louisiana since 1927.

    In 1954, to relieve flood pressure in the Mississippi River, the Morganza Spillway was built. The trigger for opening the spillway is when 1.5m cubic feet of water per second was flowing down the Mississippi River at Red River Landing, just north of the Morganza Spillway.

    Late on Friday, Louisiana state officials announced that the Army Corps of Engineers would open the Morganza Spillway within 24 hours to release some of the water as the Mississippi River reaches near-record levels.

    The opening of this spillway will channel water out of the flooded Mississippi River and into the Atchafalaya River, a low-lying area of the central Louisiana basin, for the first time since 1973. 

    Up to three million acres will be flooded in a bid to protect large cities along the Mississippi River, such as New Orleans.  Much of the water would end up in swamplands, bayous and backwater lakes but several thousand homes are at risk of flooding and as many as 25,000 people are preparing to leave their homes.

    As acres of farmland and produce are wiped out, farmers in the region are expecting to lose their entire crop. However, the US government has vowed to reimburse farmers for destroyed crops.

    Although the flooding is approaching records set 84 years ago when hundreds of people in the region died, no lives are expected to be lost during the event.

    By: Alison Cobb