Droughts

Droughts can last days, months, or even years. They happen because of a long time of there being no precipitation and high amounts of evaporation. One cause of droughts is when there is high temperatures and very humid environment, leading to high amounts of water evaporation. Global warming can also cause droughts.

Types of Droughts

There are three types of droughts. The first type of drought is Meteorological droughts. They are caused when there is a prolonged time without precipitation, and they usually happen before other types of droughts, essentially, preceding them. Hydrological droughts happen when bodies of water, such as lakes, rivers, aquifers, and reservoirs, lose a large amount of water in them. It usually happens over a long period of time because it uses stored water that is used but not refilled, or replenished. This type of drought heavily relies on water management. Agricultural droughts, or also known as ecological droughts, affect ecosystems in general. This can happen from any changes in the precipitation levels when increased irrigation, soil, and erosion are triggered by

Wind erosion is much more of a there in arid areas and during times of drought. In the great plain sit is estimated that soil loss due to wind erosion can be as much as 6100 times greater in drought years than in wet years.

Losses is a homogeneous, typically non stratified, porous, friable, slightly coherent, often calcareous, fine-grained, silty, pale yellow or buff, windblown (Aeloian) sediment. It generally happens as a widespread blanket deposit that covers areas of hundreds of square kilometers and tens of meters thick. Loses often stand in either steep or vertical faces. Loses tends to develop into highly rich soils. Under appropriate climatic conditions, areas with losses are among the most agriculturally productive in the world. Loses deposits are geologically unstable by nature, and will erode very readily. Therefore, windbreaks (such as big trees and shrubs) are often planted by farmers to reduce the wind erosion of loess.

Droughts can cause land degradation and loss of soil moisture, resulting in the destruction of cropland productivity. This can result in diminished crop growth or yield productions and carrying capacity for livestock. Drought in combination with high levels of grazing pressure can function as the tipping point for an ecosystem, causing woody encroachment.

Water stress affects plant development and quality in a variety of ways: firstly drought can cause poor germination and impaired seedling development. At the same time plant growth relies on cellular division, cell enlargement, and differentiation. Drought stress impairs mitosis and cell elongation via loss of turgor pressure which results in poor growth Development of leaves is also dependent upon turgor pressure, concentration of nutrients, and carbon assimilates all of which are reduced by drought conditions, thus drought stress lead to a decrease in leaf size and number. Plant height, biomass, leaf size and stem girth has been shown to decrease in maize under water limiting conditions. Crop yield is also negatively effected by drought stress, the reduction in crop yield results from a decrease in photosynthetic rate, changes in leaf development, and altered allocation of resources all due to drought stress.\ Crop plants exposed to drought stress suffer from reductions in leaf water potential and transpiration rate. Water-use efficiency increases in crops such as wheat while decreasing in others, such as potatoes.

Droughts can last from a week to many years. Droughts are also the second most costly natural disaster, as every year they do the most economic damage of any natural disaster other than hurricanes.

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