Loy Rego is a Tech Advisor, MARS Practitioners Network (DPRR and SDGs) & VERVE Volunteers. He also served as Deputy Executive Director, ADPC, Bangkok (1996-2011) & Joint Director, NSC, India (1986-96).
This article analyses the available data on various hydro-meteorological disasters across the globe and in Asia to highlight the alarming impacts of these disasters, particularly floods, on lives, livelihoods, and the economy.
If we look at the data analyzed by the World Meteorological Organization’s (WMO’s) Atlas of Mortality and Economic Losses, specific to Hydro-meteorological disasters, worldwide, 11 072 disasters occurred in fifty years (1970-2019) that attributed to weather, climate and water-related hazards (WCWr), resulting in 2.06 million deaths and US$ 3.64 trillion losses, also representing 50% of all disasters (including technological hazards), 45% reported deaths and 74% reported economic losses. This also means that a WCWr disaster occurred every day on average over these 50 years – killing 115 people and causing US$ 202 million losses daily.
Further, worldwide, 44% of these disasters were floods (riverine 24%). While tropical cyclones and droughts resulted in 38% and 34% of disaster deaths respectively. 38% of economic losses were caused by tropical cyclones, 31% from different flood types: riverine (20%), general (8%), and flash (3%). 91% WCWr deaths occurred in developing economies (UN classification), similar to 82% of deaths in low/ lower-middle income countries (World Bank classification), while 59% of economic losses were in developed economies and 88% of economic losses occurred in upper-middle- and high-income countries.
Top 10 disasters and losses worldwide
Hazards related to the top 10 disasters with the largest human deaths have been from four droughts (650,000 deaths), three storms (577,232), two floods (58,700), and one extreme-temperature event (55,736). Floods were the most common WCWr disasters recorded, but storms had the highest human/ economic toll. The top 10 economic loss events were seven tropical cyclones (US$ 521 billion) and three floods (US$ 115 billion).
Impacts in Asia: Floods being the Deadliest
A million lives and US$ 1.2 trillion have been lost in Asia over 50 years due to WCWr disasters. Asia had nearly one-third (31%) WCWr global disasters, nearly half of deaths (47%), and one-third (31%) of economic losses. Most of these disasters were floods (45%) and storms (36%). Storms had the highest impacts on life, causing 72% of lives lost, while floods caused the greatest economic losses (57%).
Asia’s top 10 recorded disasters caused 70% of lives lost (680 837 deaths) and 22% of economic losses (US$ 266.62 billion). Of these, tropical cyclones (TCs) were the most prevalent hazard. Three TCs (two in Bangladesh, 1970, 1991; one in Myanmar, 2008) accounted for 60% of deaths regionally. China was the most affected Asian country by WCW events, suffering half economic losses (49.7%, US$ 598 billion), in the last 50 years. Six costliest regional disasters occurred in China (60% of top 10 events). Floods were the most prevalent hazard causing economic losses.
According to the Centre for Research on Epidemiology of Disasters, (CRED), Belgium, across the globe, 2664 flood events occurred from 1900 to 2005 including 1068 (40%) flood events in Asia.
Floods: Types and Causes
Slow-onset riverine / monsoon floods occur when major rivers and their side channels rise slowly and overflow, either by snowmelt or steady ongoing rainfall, causing extensive inundation with damage/losses and slow recession lasting for many weeks/ months. Rising flood levels can be forecasted, allowing people to evacuate to higher ground. Housing is often built on stilts. Flood peaks may occur simultaneously on many interconnected rivers, which causes extensive flooding.
Rapid onset/flash floods occur mainly in rivers with small, steep mountainous catchments after periods of intense rainfall, often accompanied by the rapid rise in water levels, and sudden high-flow velocity onrush from mountains, causing intense damage to crops/property and direct life loss.
Localized urban floods occur after intense local rainfall in areas with inadequate drainage, storm-water management, and flood evacuation systems. Floodwater often remains for a long duration.
Asia also has six major river systems namely:
a) Ganges: India, Bangladesh,
b) Brahmaputra: China, Bhutan, India, Bangladesh,
c) Meghna: India, Bangladesh,
d) Indus: China, India, Pakistan,
e) Mekong: China, Myanmar, Lao PDR, Cambodia, Thailand, Vietnam,
f) Salween: China, Myanmar.
Populations residing in these river regions often suffer from floods. River’s transboundary benefits are shared, but the way in which rivers are used in upstream areas affects river flow and its impact on downstream areas. This also creates conflicts over river water use and the construction and management of dams in each country they pass through. Therefore, balanced, shared use of these complex, dynamic river systems is needed.
Floods also have levels of magnitude:
a) Periodic ‘annual’ floods with farming practices well-adapted. Forecasts give advice regarding sowing/ cropping times to minimize losses,
b) Medium (example: 5-years) floods cause some serious/ extensive economic loss, affecting people in low-lying areas by rivers, who are usually prepared,
c) Severe (example: 20-years) floods with river levels rising, affect large geographies including urban areas, damage/loss to physical environment/ economy generally significant,
d) Catastrophic (example: 100-years) flood inundating extensive areas, extremely devastating, multi-fold impacts to life, property, and economy.
Besides negative impact, riverine floods deposit rich fertile sediments that enrich nutrients lost through intensive agricultural practices of deltaic farmers downstream. These natural actions provide people with food security and farmers’ livelihood security.
Floods have meteorological, hydrological, and anthropogenic causes. Extreme, intense rainfall of long-duration and floods caused by cyclones, storms, and tidal surges are major causes of damage. Flooding is also caused by increased run-off due to ice/ snow melts; saturated land, erosion, and impermeable surfaces with poor infiltration. Floods are greatly influenced by human activities: population growth, socio-economic development, land use, deforestation, intensive agriculture, unplanned flood control measures, urbanization, and climate change. The most flood-vulnerable people are from marginalized/ impoverished groups, living on low-lying land, have less employment, and have poor access to essential services.
Conclusions
The practice of Integrated Water Resource Management (IWRM) is required to overcome the challenges and reduce people’s vulnerability to floods. IWRM focuses on maximizing floodplain use with minimum loss to life, livelihoods, and biodiversity. It helps in reducing flood risks through risk assessments, developing and applying risk management strategies; preparing people for floods, and investing in mitigation, and risk reduction. We need to reduce vulnerability, but learn to live with and adapt to floods. Lessons should be learned from examples cited in two river systems. We must build resilience, anticipate accurately, and prepare for and adapt to floods, while recognizing, celebrating, routinizing, and expanding relevant successful pilots and learning from across the globe into regular good practices, including dealing with the challenges faced.
