Drought belongs to the group of atmospheric or exogenous hazards. This implies that it happens due to external forces that arise from the outside earth’s surface (Sati, 2007). These hazards are characterized by changes in the atmosphere or some atmospheric phenomena. This atmospheric disaster is caused by accumulation of changes in various atmospheric features, which can range from a few days to several years depending on the magnitude of these changes. For instance, an exceedingly hot day may not turn out to be disastrous or a drought. However, when hot days are persistent for several days, there is the likelihood of changes in the atmosphere due to prolonged heat waves thus affecting both animal and plant lives. In this regard, drought is defined as an extended period when a certain geographic region experiences a deficiency in natural water supply. It is usually characterized by a region receiving little or no precipitation that does not meet the threshold to support animal and plant life. Droughts are not like many other hazards cumulative hazards. This is because it develops slowly but has prolonged effects and existence. Therefore, it is also called a creeping atmospheric hazard (Smith, 2008). This report contains details of how drought occurs, its impacts and how man has responded.
Methods; discloses a number of ways in which the data about draught was collected. Data was collected by use of secondary sources, which are published materials. They include books and journals. Data giving examples was selected from the many examples found in different parts of the world.
This is the least severe form of drought. It s caused by any deficit of precipitation but unusually small. Meteorological drought does not create a disaster because the amount of critical water required is indirectly related to precipitation. In other words, rainfall is not the principal supplier of rainfall to plant but instead, the earth’s surface is. Similarly, rainfall is not directly responsible for supplying the water for domestic use. The rivers and ground water does this (Smith & Petley 2009). The mechanism in which the drought occurs has resulted into a definition of rainfall using different data. The drought can be defined using a rain free period, which differs in length, in different places. Some definitions also depend on data of average rainfall registered over a period quoted against certain percentile values in relation to long-term averages. The times vary according to the region. For example, it is 6 days in Bali, 30 days in some parts for southern Canada and up to two years in Libya. For instance, the Australian bureau of metrology uses period patterns that are specific to assess this drought. If the rain falls below 10 percent of the normal averages for a period of at least three months, then the situation is declared a drought.
Hydrological drought in characterized by a mechanism where the ground water levels are sufficiently reduced thus affecting the other water resources negatively. According to Smith (2008, p. 213), ‘Hydrological drought is measured by looking at the relationship between shortfall in natural stream or underground supply with water demand’. The drought is most associated with the urban areas where there are no permanent rivers. A clear example is that of northeastern Brazil where the rivers around the city are not permanent (Carmen, 2007). The water supply there is dependent on seasonal rains whose waters are reserved in a shallow pond that are exposed to evaporation.
This is the third mechanism via which droughts manifest. It is particularly significant because it affects human activities in the greatest way. Food production is significantly affected by this drought. Agricultural drought ‘occurs in areas where the people depend solely on irrigation for food production’ (Smith 2008, 214). There is overdependence on the water supplies such as rivers and dams for water supply. Therefore, Agricultural drought occurs when the soil moisture is reduced to the extent of being unable to support plant growth. The severity of this drought is measured by using soil moisture, which is a usually assessed indirectly using index such a PDSL.
It is also referred to as an extreme form of agricultural drought. It results in wanton destruction of food security structures thus making people unable to maintain a healthy life. There is no any water to support plant growth and thus people are subjected to the great famine. The great African drought of 1984 serves as a perfect example where there were massive deaths of people in Sudan’s Darfur region. The mortality rate in this place was doubled during this great famine killing the elderly and children in higher rates. The impacts of this drought are even worse in situations where there is limited access to portable water as opposed to wetter areas because very little water is available for use. This affects health standards by affecting sanitation negatively. Another impact associate with this drought is the out-migration of rural populations in search of water resources and food. Up to one million people in the north coast of Brazil were forced to urban centers to evade the 1985 famine and to look for work (Carmen, 2007).
Response to Droughts
As an atmospheric disaster, drought occurs under the influence of different factors implying that it has different mechanisms, which result into different types of drought. These factors are categorized broadly into two: physical and human factors. Physical factors comprise of the atmospheric phenomenon that are not well understood. However, they are related to anomalies in the general atmospheric circulation of water. There is intensive research going on this where interactions between the atmosphere and oceans in being investigated (Smith & Petley 2009). Secondly, there are the human factors, which are influenced by the activities of man. This includes climate change due to global warming, deforestation and improper use of natural water related resources.
Human response to drought was mainly through evasion and endurance. Studies in southern Africa show that people have in many occasions chosen to move from the affected areas to unaffected areas. The establishment of transhumance routes characterizes the evasion strategy. Herders use this response method mostly by moving (O'Farrell, Milton, and Dean 2009). However, there are other modern ways of responding to drought. Most countries are adapting better technological strategies to respond to drought rather than continuing with the traditional ones like evasion. For example, individual farmers in Australia efficient agricultural systems to enable them mange land properly by minimizing permanent damage.
According to Bryant (2005, p. 105), ‘Cultivation practices are mainly focused on moisture conservation and improvement of water penetration mechanisms such as mulching, and construction of contour furrows.’ Many other developed countries have adopted such similar mechanism in response to drought. However, the developing world is still struggling with response especially in Africa. Poor response mechanism has resulted in massive loss of life and property in the Sahel region of Africa.
These methods have proved effective in places where they are applied. Food sufficiency has been maintained considerably for longer periods implying that they are effective. More technical response mechanisms are also prevalent. For instance, many nations have turned to irrigation thus ensuring constant supply of food and water. Other water programs such as recharging ground water levels minimizing evaporation, reducing soil salinity levels, and reducing water leakages from reservoirs usually accompany these strategies (Bryant, 2005, 116). These approaches have been successful in the United States and some African states like Egypt (Sati, 2007). Controlled use of water is also another option that has been used by most countries. The amalgamation and collective use of water resources is encouraged. The water act of 1973 in the US was designed to serve such a purpose. This method has been successful since water resources are utilized in a concerted fashion meaning that sustainability can be achieved.
Drought as an atmospheric hazard has adverse effects to the overall survival mechanism of plants and animals. This means that life can be non-existent if drought is not controlled. The mechanisms in which the drought phenomena occur is not clearly understood although there are numerous attempts to characterize tem. In this regard, human response is the most effective way to face the calamity. Many countries have adopted different methods of combating the natural calamity using different water conservation strategies. This is the only way the effects of drought can be mitigated. Response strategies vary with countries with the most developed one responding well as opposed to the developing ones. Therefore, there should be a concerted effort to assist these countries, especially those in Africa in responding to drought and its effects. Otherwise, the response to drought all over the world is effective despite the fact that some regions are still lagging behind.