If you're from the Midwest, you're all too familiar with how extreme the weather can be. Here in Nebraska we have a saying for our crazy weather,
"If you don't like the weather, wait 5 minutes."
While the weather might not change in 5 minutes, the point is the same-- the weather is often unpredictable and can change in the blink of an eye. Two years ago, Nebraska had extreme flooding while last year Nebraska had extreme drought. This last month, even this last week, we've seen large amounts of precipitation via strong thunderstorms bringing flash flooding. But lasting concerns of the drought still linger on the High Plains, why is this? The answer has to due with the difference between surface water and ground water, where our drinking water comes from and the true definition of 'drought'.
Drought is a climatological event which most people don't notice on a day to day basis. It's not in your face like the daily weather. Most of the time we don't even know that drought exists unless our yards turn brown and the city enforces water restrictions (which I remember as a kid in Nebraska). So if we get rain and the ground is wet and the plants are green, then the drought must be seeing relief, right? Wrong.
Weather Dictionary defines 'drought' as the following,
Abnormal dry weather for a specific area that is sufficiently prolonged for the lack of water to cause serious hydrological imbalance.
Not only is does drought affect an area and last for a long period of time, but also has a serious effect on water balance, which most importantly to us is our availability of drinking water. For most of us, water comes from the faucet but in reality the water we drink goes on a long journey before it makes it even close to our faucets. In the High Plains, 82% of the population relies on drinking water from the Ogallala Aquifer, one of the world's largest aquifers.
The aquifer receives recharge from various sources including mountain snow melt, prairie snow melt and spring rains. When this recharge doesn't occur, the more water we take, the less the aquifer has to maintain its saturation level. This means our availability of drinking water decreases as well!
"But Rain Girl, this month we've received over 8in of rain! Why isn't the drought seeing any relief?"
This is a good question. Lets see what the climate data for Lincoln, Nebraska shows us.
Precipitation 2013 (inches)
Precipitation Month-To-Date: 8.37
Precipitation Total since March 1st: 14.51
Precipitation Total since January 1st: 15.78
Precipitation 2012 (inches)
Precipitation Month-To-Date: 2.5
Precipitation Total since March 1st: 6
Precipitation Total since January 1st: 10
Precipitation Total for 2012: 19.14
-6th warmest year on record
-309 consecutive snow-free days
-Maximum temperature records set in January, March, April, May, June, July, September, November, and December
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| 30 year climate normal for High Plains |
The map to the left shows what normal annual precipitation should be. Where the Ogallala Aquifer is located in Nebraska, this area should receive 15 to 30 inches of rain annually. Remember from earlier that total precipitation in Lincoln, NE in 2012 was 19.14in. However, areas in western Nebraska saw total precipitation totals lower than 19.14in. So while we may be already seeing a total of over 15in this year already, in an area that should see about 35in annually, that much moisture in such a short period of time in such a drought stricken area can really only bring problems for long term issues even if it solves short term issues like renewal of surface water. As you can see in the drought monitor below to the right, as of a week ago, Nebraska is still largely in severe to exceptional drought (orange to dark red). This drought is lingering due to the extremes experienced in 2012 and the lack of recharge over this past winter.
Receiving rain may seem like a miracle at times, or even relief to drought, but the way the rain falls may mean the opposite. When large amounts of rain fall onto dry ground (or overly saturated ground), flash flooding can occur. If the ground is too dry (like it is now when we're in drought) the water is not absorbed into the ground and instead results in flash flooding. Flash flooding is very dangerous making roads impassible, floods crops and creates run-off taking crops, chemicals and more with it which goes to water features like streams, lakes and rivers. Therefore, the 8in of rain we've seen this past month may saturate the surface, but doesn't recharge ground water because it's staying at the surface wreaking havoc for us who live on the surface.
So while we may be seeing flooding (whether flash or long term) this does not necessarily mean drought relief is in sight. Drought and flooding both affect our drinking water as well as the crops which we feed on (directly and indirectly). Because drought is such a deep issue in the land and hydrological systems, it won't be relieved by rain brought by strong storms. What this land needs is a good 'soaker' rain which is a nice, slow, but consistent rain that allows the ground to absorb the water it is receiving.
My personal opinion is that this year will bring more drought and little relief will be seen but strong thunderstorms will persist through the summer season, most likely creating more issues for an already drought stricken land.
Data & Map Sources
- High Plains Region Climate Center
- National Weather Service
- Weather Dictionary
- US Drought Monitor Archives
- Kansas Ag Network
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