August 28, 2012

The Benefits of Tropical Storms and Hurricanes

Although there is a lot of media coverage of the damage and destruction accompanying tropical storms and hurricanes, such storms can also have important benefits.

For example, landfalling tropical storms can be an important source of water, water that can lessen droughts and recharge underground aquifers. 

For example, take tropical storm Isaac.  As many of you know, there has been a major drought in the mid-section of the nation, as illustrated by the graphic below:

Severe drought extends from northern Louisiana, through Missouri and Iowa, into Illinois and Indian.  And west into the Great Plains.  The Mississippi River has been running very low, with serious impacts on marine transportation, and the effects on agriculture have been profound.

The latest forecast models indicate that Isaac will bring soaking rain though much of this drought region.  For example, here is the predicted cumulative rainfall through Sunday at 11 AM PDT from the National Weather Service GFS model.  Note that a band of 4-10 inches extends through much of the drought zone.  The impact of this rain will be substantial and positive.

In fact, the moisture from Isaac will continue into the Northeast, damping down the dry conditions over upstate NY (see precip totals through late Tuesday):

The benefits of tropical storms and hurricanes doesn't end with rainfall.  It turns out the such storms can help maintain and build barrier beaches, such as those that line the East Coast.   Orrin H. Pilkey, James B. Duke Professor Emeritus of Geology at the Nicholas School of the Environment and Earth Sciences at Duke, noted that "Barrier islands need hurricanes for their survival, especially at times of rising sea levels such as now. It's during hurricanes that islands get higher and wider. From a purely natural standpoint hurricanes are a blessing for islands, even though they're a curse for people who live there." 

Hurricanes and tropical storms produce overwash of sand, and without that the islands get skinnier and skinnier and might disappear as sea level rises.

Overwash During Tropical Storms Can Help Maintain Barrier Islands
Most of the damage during hurricanes is along the coastal zone due to storm surge and associated flooding.   Too many people and structures are located along the coast and put themselves at risk.  To protect themselves, all kinds of geoengineering approaches are installed (e.g., jetties), many of which cause more problems then they solve.


  1. Sometimes, bad things can be good

  2. Cliff, as a Westerner I have wondered if soaking rains like hurricanes actually do recharge aquifers; a large amount of rainfall in the West (especially if on a deforested or denuded slope) seems to pull nutrients and soil downslope. Do the different ecosystems of the Mississippi Valley and the Great Plains - wetter, flatter, more vegetation - allow for hurricane-type rains to soak into the groundwater aquifers more readily? Thanks for all your helpful info!

  3. Cliff,

    Check this out. Looks very interesting for an 'art project'.


  4. But the danger of so much rain after a drought is that at first the soil can't absorb all it and this could lead over-ground flow and to flash flooding. It would be best if the rain begins slowly allowing the infiltration rate to increase. If the rain begins in torrents it can be bad news before these benefits begin.


  5. Cliff - have we had an unusual amount of hurricanes staying out in the middle of the atlantic?

  6. Speaking of drought. We made it through Tues/Wed without any official precip at Sea-Tac and now there is no precip predicted in the near future. The dry streak lives! 51 here we come???

  7. I think that's a good point. Typically when those storms become extra-tropical the threat for severe weather decreases and the rain is heavy but not torrential.

    It's unfortunate they don't typically make it a little further west into Kansas where I'm from.

  8. Just like forest fires have benefits, I knew storms often bring much needed rain but I wondered if there were other benefits.


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