Md. Arafat Rahman :
The chronic deficit in water supply is termed drought. A drought can last for a month or even a year. Drought conditions are caused by prolonged dry weather and insufficient rainfall. This occurs when evaporation and transpiration are greater than precipitation. During drought, the drought affected areas become hot and wells, canals dry up resulting in scarcity of usable water. River flows decline, groundwater levels drop and soil moisture becomes deficient, field crops dry up, crop failures occur, and livestock feed shortages occur. Drought is a major problem for communities that depend directly on rain for drinking water and farming. Since ancient times, this natural disaster has had far-reaching effects on mankind. Drought has been associated with the collapse of many ancient civilizations.
People generally view drought as a disaster because of its impact on food availability and the rest of society. People have often tried to explain drought as a man-made natural disaster or the result of supernatural forces. It is one of the oldest climatic events. Rituals existed to prevent or avoid drought from rain-making dances to human sacrifices. Those ancient practices are largely based on folklore and have been replaced by more rational water management.
Global climate change is having a significant impact on agriculture around the world and especially in developing countries, which is an early stage of the onset of drought. Flooding may increase along with drought in some areas. Some proposed solutions to global warming focus on more proactive strategies. E.g.: Solar radiation management through the use of a space sunshade.
According to the Intergovernmental Panel on Climate Change’s Special Report on Climate Change and Land, climate change increases drought and desertification. Hundreds of millions of people are affected. Affected areas include large areas of Africa, Asia, Australia and South America. The impacts of drought and water scarcity can be divided into three categories: environmental, economic and social. Environmental impacts include: lower surface and groundwater levels, increased surface water pollution, drying up of wetlands, greater wildfires, loss of biodiversity, poor tree health and the presence of pests.
Economic losses include lower agriculture, higher food-production costs, lower energy-production losses due to reduced transportation revenues, water supply problems for the energy sector, and water supply disruptions for municipal economies. Social harms include negative health impacts on people directly, potential water supply constraints, increased pollution levels, high food-costs, etc. This explains why drought and scarcity of fresh water acts as a factor that widens the gap between developed and developing countries.
When the soil moisture is less than the moisture required for crop production during the normal growing season, the period is called drought condition in Bangladesh. Drought outbreaks occur occasionally in the north-western districts of Bangladesh. Many times famine occurs due to this drought. A definite sign of the onset of drought is the scorching of bamboo and betel leaves, i.e. the loss of their green foliage, and the new leaves turning pale due to lack of moisture in the soil and air. If there is no rain for a long time or irrigation water is not supplied, the plant will almost die. Even in areas with sufficient rainfall and humidity, droughts can sometimes occur.
Frequent outbreaks of drought have become a feature of the Barendra region of Bangladesh in recent decades. This includes Dinajpur, Rangpur, Pabna, Natore, Rajshahi, Bogra, Joypurhat and Naogaon districts. Rainfall in Barendra zone is relatively less than other parts of the country. This particular region of the country is generally considered to be hot and semi-arid. This region has distinctly extreme weather conditions in contrast to the climatic conditions of the rest of the country.
From a meteorological point of view, drought can be divided into three categories, namely: permanent drought, which is a feature of dry climates; Seasonal drought, which occurs due to disruption of the normal pattern of monsoon and winter; and sudden droughts caused by erratic rainfall. In the case of Bangladesh, the last two types of drought are usually more common. Due to the hydrological and climatic characteristics of Bangladesh, excess water during the wet monsoon season and less water supply during the dry season creates a drought environment.
Due to the withdrawal of water in the upstream areas of Bangladesh through the construction of water management structures for economic and domestic use, the normal flow of the rivers is being obstructed. The rivers are losing their normal flow due to the impact of Farakka Dam on the Ganges and such other dams and water structures on the Punarbhaba and Teesta. In addition to water scarcity in the rivers of northwest and southwest regions of the country, there is a negative impact on the recirculation of underground water. As a result, drought often occurs in these two regions of Bangladesh due to lack of moisture.
(The writer is Asst. Officer, Career & Professional Development Services Department, Southeast University).
