As this moose cavorts in the marsh below the forest he demonstrates that meteorological and hydrological droughts are different. The trees that have died relied largely on regular snowfall to keep them hydrated and resistant to pine beetles. Hydrologically there is still a lot of water to be had.
The impact dead trees in the forest due to drought and disease can have on recreation is immeasurable. The people on the four wheelers ride through a stand that has been decimated by the drought. Forests like this are likely to get less visitation. That can hurt the local economy.
A drought is a drought is a drought is a drought....
Or so most people think.
It would seem that drought means a lack of water or precipitation. But when the University of Nebraska researchers Donald A. Wilhite and Mark D. Svoboda did studies on how droughts are classified a few years ago, they found more than 150 definitions of drought.
The reason for that is the perception we each have about our relationship to our environment. A farmer in the mid-west who relies on rain for soil moisture to germinate his corn or grain seed may see a real problem when the water in the soil is not enough to do so properly. Thus he may have a very reduced harvest or even none at all.
The person living in the small town just up the road from his farm may realize that the rains had not come on as strong that same spring or that the winter snows were not as deep, but as long as they have water to drink and water to wet their lawn, there is no drought.
That drought for the farmer only impacts the town dweller when the two meet in the market of economics. If the farmer's harvest is poor, he may not have enough feedstock for his cattle so he may reduce his herd. At first the town dweller gets a low price on hamburger at the supermarket because of this glut of meat on the market. But later the price may go way up because there is no meat on the market once the farmer has sold off everything. In addition, the farmer may quit farming and the obvious result is no production that year or in the future either.
The explanation is simplistic but the basic idea is true. People see drought only when it affects their lives.
The National Drought Mitigation Center says that droughts should be classified in different ways, although they are all interrelated. They say that all droughts are either meteorological, hydrological, agricultural, or socioeconomic. They didn't define it as only one but as a mixture of the four ways of definition. Meteorological, hydrological and agricultural droughts are ways to measure the lack of moisture, precipitation and water. The socioeconomic drought measures what happens to goods and services because of a lack of water.
Meteorological droughts are based on dryness in a place or region as compared to what has normally taken place in the past. So a place that normally gets 80 inches of rain a year, but only gets 40 in some years is said to be in a drought, despite the fact this may seem to be a lot of water for someone from eastern Utah where 40 inches a year would be a flood.
This type of drought is measured against normals: amount of water in a certain time period, how many days it goes without raining or how much less water falls within that time period. For instance, the time between rainstorms on the big island of Hawaii would be very different from how many storms an area such as Carbon County would get almost any time of the year. The monsoon that hits eastern Utah almost every July and August seems wet to the residents of the area, but by Hawaiian standards it would be a drop in the bucket.
Next is the hydrological drought. This kind of drought concerns itself with more than what is falling out of the sky today or tomorrow. It measures some of the moisture in this way, but also looks at water tables, reservoir storage, stream flow and snow pack in areas that feed streams. It is figured on both the surface water available and what is in underground aquifers. Rather than an area or a region, it usually considers a watershed such as a river basin or a drainage in its definition of whether there is enough water. Often hydrological drought is not in sync exactly with meteorological drought.
What this means is what the eastern Utah area experienced last year and somewhat this year. Two winters ago was a very heavy winter in the mountains. Reservoirs filled up, ground moisture was high and aquifers became somewhat replenished. Last year was dry by meteorologic standard, but because of these reserves, water was normally available for municipal/ industrial and agricultural use.
This past winter was not much better in terms of moisture. There was more snow in the Castle Country valleys than the year before, but snow in the high country was deficient. Much of what melted in the spring went to replenishing soil moisture where it fell in the form of snow. Consequently stream flow was low in most places and the reservoirs did not fill up like the season before. Impacts are starting to be felt, but still are not what they could be unless the meteorological drought continues. Since storage systems are owned and managed by many competing kinds of users, as the weather stays dry, the competition for what remains, becomes greater. This is when the house of cards starts to come down and it usually impacts agriculture first and then the rest of the users.
Agricultural drought comes when there is not enough moisture to start crops or to continue them to flourish during growing season. Obviously the basis for any strong plant whether it be alfalfa or a tree is proper nourishment and moisture when the plant begins to grow. This being said, however, if there is some rain in the spring when a plant starts to grow (despite overall meteorological and hydrological drought) the plant will get a good start. However if halfway during the growing season, moisture is curtailed or stopped, the plant will either wither and die or it will produce much less yield than it would in a good year.
The affect on agriculture depends on many factors including the soil a plant is growing in, the actual amount of natural precipitation, evapotranspiration, overall weather conditions (hot or cool) the biology of the plant that is being grown along with that stage of growth it is in when water is less readily available.
For instance, farmers in the area almost always get three crops of alfalfa off their fields and if the weather holds and is right sometimes four. But in a year when the drought is hard both from a weather standpoint and a storage of water viewpoint, water deliveries may be curtailed either partially or completely. In this case one or even two crops (or even more) could be lost. If the deficiency comes early to the crop, the yield could also be much lower. This is just one instance of where the idea of socioeconomic drought would meet the other three.
Socioeconomic drought comes when the water supply (in many or all forms) curtails the direct economic well being of an area. In this case it could mean a loss of income to those in agriculture or manufacturing. This could result in loss of money to spend in a community and the loss of or reduction in employment.
It could mean the curtailment of some services such as car washes or even recreation such as golf because fairways and greens dry up. It could curtail power generation. Restrictions on water use can mean a loss of income to water companies which rely on amounts billed to customers to make them solvent. The reduction could even mean less recreation such as fishing and water sports in lakes or reservoirs that are very low. Forage for game animals could also be affected reducing their populations and therefore their predators populations.
One shouldn't also forget what can happen when large areas of land are dry. Wildfires can occur that are both devastating to the natural growth and human structures as well. And the costs to fight fires can be extreme.
And because of that, all these lacks in a local economy affects tourism and recreation as well. If people can't play in an area that depends on recreation, they will not come.
Except in terms of a meterological drought, none of these definitions can stand alone. They all begin in one way or another with the weather, and what mother nature provides as moisture to an area. And when water is lacking everyone can be hurt either indirectly or directly.