Drought. Definitions. Causes. Types.

Drought occurs when there is less water available than what is normally expected in a particular location and season. It can last for days, months or years, and has severe impacts on ecosystems, agriculture and the economy. Droughts are becoming more severe and unpredictable due to climate change. There are three kinds of drought effects: environmental, economic and social. Environmental effects include the drying of wetlands, more and larger wildfires, and loss of biodiversity. Economic consequences include disruption of water supplies, lower agricultural outputs and higher food-production costs. Social and health costs include negative impacts on health, stress from failed harvests and water scarcity. Prolonged droughts have caused mass migrations and humanitarian crises. Some plant species have adapted to tolerate drought, but most arid ecosystems have inherently low productivity. The most prolonged drought in recorded history continues in the Atacama Desert in Chile. Humans have historically viewed droughts as disasters and have attributed them to natural or supernatural forces.

Definition

IPCC defines drought as "drier than normal conditions"

National Integrated Drought Information System defines drought as "a deficiency of precipitation over an extended period of time (usually a season or more), resulting in a water shortage"

National Weather Service office of the NOAA defines drought as "a deficiency of moisture that results in adverse impacts on people, animals, or vegetation over a sizeable area"

Drought is a complex phenomenon related to the absence of water, which is difficult to monitor and define.

Over 150 definitions of "drought" were published by the early 1980s, reflecting differences in regions, needs, and disciplinary approaches.

Types

There are three categories of drought: meteorological, hydrological, and agricultural or ecological drought.

Meteorological drought occurs due to lack of precipitation.

Hydrological drought is related to low runoff, streamflow, and reservoir storage.

Agricultural or ecological drought causes plant stress from a combination of evaporation and low soil moisture.

Socioeconomic drought occurs when the demand for an economic good exceeds supply due to a weather-related shortfall in water supply.

Meteorological drought usually precedes the other kinds of drought.

Hydrological drought tends to show up more slowly because it involves stored water that is used but not replenished.

Agricultural or ecological droughts affect crop production or ecosystems in general.

Agricultural drought can be caused by increased irrigation or poorly planned agricultural endeavors leading to soil conditions and erosion.

Causes

Precipitation mechanisms include convective, stratiform, and orographic rainfall, and precipitation can be categorized into three types.

Droughts mainly occur in areas with already low rainfall levels and can be triggered by high levels of reflected sunlight, continental winds, and high pressure systems.

The dry season in the tropics increases the occurrence of droughts, and bushfires are common due to the lack of water in the plants.

El Niño and La Niña events can exacerbate drought conditions in various regions around the world.

Climate change is expected to cause droughts with a significant impact on agriculture, increase the frequency of extreme events, and worsen compound warm-season droughts in Europe.

Comments

Geography of Landslides. Mitigation and Resilience.

A landslide is a geological event in which a mass of rock, earth, or debris moves down a slope under the force of gravity. Landslides can range in size from small to large and can be triggered by natural events such as heavy rainfall, earthquakes, or volcanic activity, or by human activities such as construction or mining. The geography of landslides is affected by a variety of factors that can increase the likelihood of landslides occurring in a particular area. These factors include slope angle and steepness, the type of soil and rock present, the climate and weather patterns of the region, the presence or absence of vegetation, and human activities such as construction, mining, and deforestation. Areas with steep slopes are more prone to landslides because gravity has a stronger effect on loose soil and rock, making it more likely to move downhill. Similarly, areas with loose, sandy soil or weak, fractured rock are more prone to landslides because they are less stable and more easil

Disaster Management. Geography of Disaster Management.

Disaster management refers to the process of preparing for, responding to, and recovering from disasters or emergencies that may affect communities, regions, or entire countries. It involves the coordination of various activities and efforts by government agencies, non-governmental organizations, and other stakeholders to minimize the impact of disasters and promote the well-being of affected populations. The process of disaster management can be broken down into four phases: Mitigation: This involves taking steps to reduce the risk of disasters, such as identifying and addressing potential hazards, developing emergency plans, and improving infrastructure and systems. Preparedness: This involves preparing for the possibility of a disaster, such as training emergency responders, conducting drills and exercises, and stockpiling necessary supplies. Response: This involves taking immediate action during and immediately after a disaster, such as rescuing people, providing emergency medical

Landslide

Landslides are a type of "mass wasting," where soil and rock move down-slope due to gravity. Landslides can be caused by a combination of factors, such as rainfall, snowmelt, changes in water level, and human activities. There are five modes of slope movement, including falls, topples, slides, spreads, and flows, which vary depending on the type of geologic material. Debris flows and rock falls are common types of landslides. Landslides can also occur underwater, known as submarine landslides, and sometimes cause tsunamis. Landslides occur when down-slope forces exceed the strength of the earth materials that compose the slope. Slopes already on the verge of movement are more susceptible to landslides, which can be induced by earthquakes, volcanic activity, and stream erosion. There are four main types of movement: falls, topples, slides (rotational and translational), and flows. Landslides can involve just one of these movements or a combination of several. Geologists also

Disaster Management Act, 2005. National Disaster Management Framework (NDMF) National Disaster Management Authority (NDMA). National Institute of Disaster Management (NIDM). National Disaster Response Force (NDRF)

Disaster Management Act, 2005. National Disaster Management Framework (NDMF) National Disaster Management Authority (NDMA). National Institute of Disaster Management (NIDM). National Disaster Response Force (NDRF) The National Disaster Management Framework (NDMF) in India is a comprehensive policy document that provides a framework for managing disasters in the country. The framework was first introduced in 2005 and was updated in 2019. The NDMF is based on the principle of an integrated approach to disaster management. It aims to bring together all stakeholders, including the government, non-governmental organizations (NGOs), civil society, and the private sector, to work towards a common goal of disaster management. The framework is designed to address all phases of disaster management, including prevention, preparedness, response, and recovery. It provides guidelines for various aspects of disaster management, including risk assessment, disaster planning, early warning systems, sear

Landslides. USGS

Landslides. TYPES OF LANDSLIDES The term "landslide" describes a wide variety of processes that result in the downward and outward movement of slope-forming materials including rock, soil, artificial fill, or a combination of these. The materials may move by falling, toppling, sliding, spreading, or flowing. The animated GIF shows a graphic illustration of different types of landslides, with the commonly accepted terminology describing their features. The various types of landslides can be differentiated by the kinds of material involved and the mode of movement.

Vineesh V, Geography

Search This Blog