Droughts and Floods

Journal of Geophysical Research: Atmospheres, 2020

 Developed a hydrologic framework based on the well-calibrated VIC-SIMGM to implement integrated drought index (IDI) for 1951-2016 period in India  Drought onset and termination occurs during the monsoon season for the majority of drought clusters in India  ENSO, IOD, and SST anomalies in the Indian and Atlantic Oceans are associated with droughts in different regions of India

npj Climate and Atmospheric Science

Flash droughts cause rapid depletion in root-zone soil moisture and severely affect crop health and irrigation water demands. However, their occurrence and impacts in the current and future climate in India remain unknown. Here we use observations and model simulations from the large ensemble of Community Earth System Model to quantify the risk of flash droughts in India. Root-zone soil moisture simulations conducted using Variable Infiltration Capacity model show that flash droughts predominantly occur during the summer monsoon season (June–September) and driven by the intraseasonal variability of monsoon rainfall. Positive temperature anomalies during the monsoon break rapidly deplete soil moisture, which is further exacerbated by the land-atmospheric feedback. The worst flash drought in the observed (1951–2016) climate occurred in 1979, affecting more than 40% of the country. The frequency of concurrent hot and dry extremes is projected to rise by about five-fold, causing approxi...

Weather and Climate Extremes, 2016

Drought characteristics for the Indian monsoon region are analyzed using two different datasets and standard precipitation index (SPI), standardized precipitation-evapotranspiration index (SPEI), Gaussian mixture model-based drought index (GMM-DI), and hidden Markov model-based drought index (HMM-DI) for the period 1901-2004. Drought trends and variability were analyzed for three epochs: 1901-1935, 1936-1971 and 1972-2004. Irrespective of the dataset and methodology used, the results indicate an increasing trend in drought severity and frequency during the recent decades (1972-2004). Droughts are becoming more regional and are showing a general shift to the agriculturally important coastal south-India, central Maharashtra, and Indo-Gangetic plains indicating higher food security and socioeconomic vulnerability in the region.

2011

"DROUGHT is a complex, slow-onset phenomenon of ecological challenge that affects people more than any other natural hazards by causing serious economic, social and environmental losses in both developing and developed countries. The period of unusual dryness (i.e. drought) is a normal feature of the climate and weather system in semi-arid and arid regions of the tropics, which covers more than one-third of the land surface and is vulnerable to drought and desertification. A drought is an extended period where water availability falls below the statistical requirements for a region. Drought is not a purely physical phenomenon, but instead is an interplay between natural water availability and human demands for water supply. There is no universally accepted definition of drought. It is generally considered to be occurring when the principal monsoons, i.e. southwest monsoon and northeast monsoon, fail or are deficient or scanty. Monsoon failure causing crop failure, drying up ecosystems and shortage of drinking water results in undue hardship to the rural and urban communities. Although droughts are still largely unpredictable; they are a recurring feature of the climate. Drought varies with regard to the time of occurrence, duration, intensity and extent of the area affected from year to year4. Land abuse during periods of good rains and its continuation during periods of deficient rainfall is the combination that contributes to desertification. Dry regions in India include about 94 mha and about 300 million people (one-third of India’s population) live in these areas; more than 50% of the region is affected by drought once every four years6. Different countries and states have developed codes, manuals, procedures, processes and policies for monitoring and management of drought with varying understanding. Over the years, India has developed a fairly elaborate governance system of institutionalized drought monitoring, declaration and mitigation at different levels. India’s response to the need for enhanced drought management has contributed to overall development. For example, the drought of 1965–1967 encouraged the ‘green revolution’, after the 1972 drought employment generation programmes were developed for the rural poor; the 1987–1988 drought relief effort focused on preserving the quality of life."

Journal of Water and Climate Change, 2021

Most of the existing studies on meteorological drought suggest more intense and frequent drought events due to changing climate. However, basin-scale assessment of future agricultural drought is lacking due to many reasons. In this study, the intensity and frequency of future agricultural drought (characterized by the Standardized Soil Moisture Index, SSMI) for 226 sub-basins across India are analyzed, and vulnerable basins are identified. The prediction of the future agricultural drought status is achieved using the wavelet-based drought temporal consequence modeling of meteorological drought with the best performing bias-corrected Coordinated Regional Downscaling Experiment (CORDEX) simulations, selected by Multi-Criteria Decision-Making frameworks. This study reveals a geographically contrasting change in future agricultural drought that indicates more intense agricultural drought in north, northeast , and central India as compared with south India. The area under drought is also expected to increase, and about 20 and 50% of the Indian mainland is expected to suffer from extreme (SSMI À2) and moderate (SSMI À1) agricultural drought conditions by the end of this century. Sub-basins lying in north and central India are expected to have a longer time under drought conditions. Thus, the findings of this study will be useful for future planning and preparedness against agricultural productivity. Key words | agricultural drought, climate change, Coordinated Regional Downscaling Experiment (CORDEX), future assessment, Standardized Soil Moisture Index (SSMI) HIGHLIGHTS • Future agricultural drought status reveals new insights into its spatial variation. • The concept of drought translation is a useful one for making use of the best potential of climate model simulations. • More intense droughts in north, northeast and central India are expected as compared with south India. • In future, about 20 and 50% of the area in India is expected to face extreme and moderate agricultural droughts, respectively.

Journal of Earth System Science, 2011

The occurrence of exceptionally heavy rainfall events and associated flash floods in many areas during recent years motivate us to study long-term changes in extreme rainfall over India. The analysis of the frequency of rainy days, rain days and heavy rainfall days as well as one-day extreme rainfall and return period has been carried out in this study to observe the impact of climate change on extreme rainfall events and flood risk in India. The frequency of heavy rainfall events are decreasing in major parts of central and north India while they are increasing in peninsular, east and north east India. The study tries to bring out some of the interesting findings which are very useful for hydrological planning and disaster managements. Extreme rainfall and flood risk are increasing significantly in the country except some parts of central India.

International Journal of Engineering Sciences & Research Technology, 2013

Globally changing climatic conditions have shown direct and indirect impact worldwide. In Indian continent drast changes have been recorded in hydrological conditions, Himalayan glaciers, agriculture production and water resources. As per the IPCC studies the amount of energy reaching the earths atmosphere every second on a surface area of one square meter facing the sun during daytime is about 1370 Watts and the amount of energy per square meter per second averaged over the entire planet is one quarter of this. In one of the most productive regions of India i.e., Ganga Plain approximately 250 million people are f Climate warming and anthropogenic pressure has greatly threatened the meteorological conditions, agricultural production and causing large hydrological variations in different parts of India and surrounding Prominent changes have been recorded in the drainage morphology, crop production and precipitation patterns. These changes are modifying the land use and land cover pattern, cropping pattern, drainage pattern and over exploitation of water resources are modifying the hydrological cycle. The frequency of floods and drought and its intensity has increased manifold. About 65% population of India is agricultural based and in the long run climate change will affect the quantity and quality of the cro already high food inflation in the country. The aim of this study is to understand the globally changing climatic conditions and its impact worldwide and on Indian continents and come up wi solutions effective it address the problem of water and food scarcity in future. Abstract Globally changing climatic conditions have shown direct and indirect impact worldwide. In Indian continent drast changes have been recorded in hydrological conditions, Himalayan glaciers, agriculture production and water resources. As per the IPCC studies the amount of energy reaching the earths atmosphere every second on a surface the sun during daytime is about 1370 Watts and the amount of energy per square meter per second averaged over the entire planet is one quarter of this. In one of the most productive regions of India i.e., Ganga Plain approximately 250 million people are facing severe problem of water and food scarcity. Climate warming and anthropogenic pressure has greatly threatened the meteorological conditions, agricultural production and causing large hydrological variations in different parts of India and surrounding Prominent changes have been recorded in the drainage morphology, crop production and precipitation patterns. These changes are modifying the land use and land cover pattern, cropping pattern, drainage pattern and over urces are modifying the hydrological cycle. The frequency of floods and drought and its intensity has increased manifold. About 65% population of India is agricultural based and in the long run climate change will affect the quantity and quality of the crops and the crop yield is going to be down. This will increase the already high food inflation in the country. The aim of this study is to understand the globally changing climatic conditions and its impact worldwide and on Indian continents and come up with easily and economically feasible solutions effective it address the problem of water and food scarcity in future.

2019

 Abstract—The climatic condition over Indian region is highly dependent on monsoon. India receives maximum amount of rainfall during southwest monsoon. Indian economy is highly dependent on agriculture. The presence of flood and drought years influenced the total cultivation system as well as the economy of the country as Indian agricultural systems is still highly dependent on the monsoon rainfall. The present study has been planned to investigate the flood and drought years for the north-west Himalayan region from 1951 to 2014 by using area average Indian Meteorological Department (IMD) rainfall data. For this investigation the Normalized index (NI) has been utilized to find out whether the particular year is drought or flood. The data have been extracted for the north-west Himalayan (NWH) region states namely Uttarakhand (UK), Himachal Pradesh (HP) and Jammu and Kashmir (J&K) to find out the rainy season average rainfall for each year, climatological mean and the standard deviat...

Journal of Geophysical Research: Atmospheres, 2014

Precipitation pattern has changed over many regions in recent decades. There are evidences of increased heavy precipitation and decreased light precipitation in widespread parts of the globe due to global warming. Many studies over Indian region focus on heavy precipitation and risk of floods. But few works discuss the changes in light precipitation and risk of droughts. In this study, changes in total dry days, prolonged dry spells, light precipitation, and risk of drought as indicated by Modified Palmer Index (MPI) over India during six decades are examined quantitatively in the context of global warming. It is found that there are increases of 49% ± 21% and 33% ± 17% in prolonged dry spells and total dry days, respectively, over India for each degree Kelvin (K) increase in global mean temperature. There is an increase of 51% ± 24% K À1 in drought index MPI (<= À 2.0). There is also a reduction of 31 ± 14% K À1 in light precipitation days over India. These changes are more severe over northeastern and western part of India. Increases in prolonged dry spells, total dry days, and decreases in light precipitation relate well with the increases in drought index MPI (<= À 2.0). These results suggest that there is an increased risk of drought due to increased prolonged dry spells, total dry days, and decreased light precipitation days over India as a result of global warming.

Weather, Climate, and Society, 2019

In the prevailing climate change scenario, to cope with drought, it is necessary to understand the characteristics of meteorological droughts in water-scarce regions to formulate judicial plans for the utilization of water resources. The present investigation, therefore, endeavored to assess the intensity and frequency of droughts over the five semiarid river basins in Maharashtra during the past (1980-2013) and future (2015-50). The study was carried out with the application of standardized precipitation index (SPI) methodology. The agricultural and satellite [normalized difference vegetation index (NDVI)] data were analyzed to understand the effects of meteorological droughts. Although the study area experienced three severe rainfall droughts in 1985/86, 2002/03, and 2011/12, higher frequency of low-intensity droughts is observed, particularly after 2000. The estimation suggests occurrence of moderate, severe, and extreme droughts once in 6, 28, and 50 years, respectively. Among the selected basins, the Agrani, the Karha, and the Man are expected to experience intense droughts and hence require special attention in drought management. The study also highlights that El Niño events considerably retard the monsoon rainfall. However, the occurrence of the positive phase of the Indian Ocean dipole in the El Niño years reduces the intensity of droughts. As agricultural productivity and cropped areas heavily depend on the monsoon rainfall, the meteorological droughts result in agricultural droughts. Moreover, the future warming (by 1.028C) over the study area is very likely to exacerbate the meteorological droughts (estimated to occur in the 2030s) and increase the agricultural water demand, further adding to an already difficult water management challenge in the study basins.

Atmosphere

South Asian countries have been experiencing frequent drought incidents recently, and due to this reason, many scientific studies have been carried out to explore drought in South Asia. In this context, we review scientific studies related to drought in South Asia. The study initially identifies the importance of drought-related studies and discusses drought types for South Asian regions. The representative examples of drought events, severity, frequency, and duration in South Asian countries are identified. The Standardized Precipitation Index (SPI) was mostly adopted in South Asian countries to quantify and monitor droughts. Nevertheless, the absence of drought quantification studies in Bhutan and the Maldives is of great concern. Future studies to generate a combined drought severity map for the South Asian region are required. Moreover, the drought prediction and projection in the regions is rarely studied. Furthermore, the teleconnection between drought and large-scale atmosphe...

Proceedings of ISPRS …, 2009

International Journal of Current Microbiology and Applied Sciences, 2018

In Asia, more than a billion people could be affected by a decline in the availability of freshwater, particularly in large river basins, by 2050. Glacier melt in the Himalayas, which is projected to increase flooding and rock avalanches, will affect water resources in the next two to three decades. As glaciers recede, river flows will decrease. Coastal areas, especially heavily populated mega-delta regions, will be at greatest risk due to increased flooding from the sea and, in some cases, from river flooding.