To most people, the definition of drought is along the lines of "not having rain for a long time." While this is mainly true, there are many aspects to a drought. For example, a drought in Texas would be much different from a drought in Maine.
There are four main types of drought:
- an agricultural drought is the lack of moisture in the soil to meet the needs of a crop.
- a meteorological drought is determined by a region's climate.
- a socioeconomic drought is when water deficiency affects people.
- a hydrological drought is one that deals with levels of lakes, reservoirs and groundwater levels.
The severity of droughts is often measured by the Palmer Drought Severity Index (PDSI). The PDSI, which is most useful with long-term droughts, gauges dryness by using information regarding temperature and rainfall. Because it is standardized to local climate, it can be used nationwide.
If an area has normal conditions, a PDSI would be a 0.
When drought conditions occur, the area would be represented
on the scale as a negative number. For example, a moderate
drought would range between -2 to -2.99, a severe drought
would range between -3 to -3.99 and an extreme drought would
be -4 and below on the PDSI scale. In addition to dryness, the
guide can also be used to measure excess moisture. The scale is
the same as the drought, but with positive numbers such as two
for moderately moist.
Regardless of the type or severity, repercussions of a drought can be severe.
The increased risk of wildfire, the possible loss of crops and livestock, the reduced recreation,
and the negative impacts on wildlife habitats and other environmental consequences are all results of
Some communities in the Brazos basin have already seen the initial effects of regional
droughts resulting in burn bans and irrigation restrictions. Check with your local utility for possible
Has a drought crept into your backyard? Click
here for an up to date look at rainfall
in your area.