When Does a Drought Begin, When Does it End?
A drought is defined as a "prolong period of time with below normal precipitation" There are other definitions pertaining to crop damage but they too are rather vague. Another definition I like is when precipitation drops below 75 percent of normal but it does not say how long it must be below 75 percent? So, it is hard to designate when a drought officially begins and even more difficult to determine when it ends? John reported last weekend up by Webster in northern Rice County they received 5.75 inches of rain and more last night. Is the drought over for them?
The general rains we have received in the last few days is sure a step in the right direction but I don't think you can say the drought is over just yet! Again, there are a number of ways to measure when a drought is over. The one I like refers to when surface waters and ground water are back to normal for this time of year. That means water flow in rivers, creeks and drainage ditches being back to normal, or tile lines running again too!
For that to occur you need general soaking rains for a longer period of time than a week. Mark from northwest of Nerstrand called in a rain gauge report this morning and said a neighbor dug a hole 10 feet deep. It was dry all the way down to the bottom. It is going to take a lot more rain over an extended period of time to get subsoil moisture back to normal.
So, watch the rivers, creeks, drainage ditches, lakes and even ponds this fall. I watch my drainage ditches and the Cobb River just south of my farm. It has not been running most of this summer. When they are back to normal then YOU can decide if the 2021 drought is over. In the picture is the last U.S. Drought monitor released yesterday. I was told this is the first time we have had D4 Exceptional drought in Minnesota. It is going to take a lot of rain before we are back to normal and can say the drought is over!
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