- By Tekatho Zaw Htoo Oo
This year’s monsoon season has brought flash flood hazards, including heavy flooding and landslides, to many parts of the country. Not only in Myanmar but also its neighbouring countries have been enduring these devastative natural disasters, such as flood damage, wind hazards, storms and earthquakes due to severe climate change.
The main monsoon season in Myanmar runs from June to October, and the country usually encounters flash floods, strong winds, and heavy rains since the beginning of the monsoon season. Normally, floods occur in Myanmar as water overflows from the monsoon months of June to October, but the country suffers its monsoon flooding most in July and August. This can occur in a multitude of ways. Rain water flows into the Ayeyawady, the Chindwin, the Sittaung and the Thanlwin rivers as well as into many of its tributaries, which can lead to overflowing of the waterways. Storms can also cause unexpected flooding sometimes. Heavy rainfalls, accompanied by a storm surge, can cause flash flooding in many towns and villages located near the rivers.
A flash flood occurs when water overflows on or inundates land that is normally dry. Rivers can overflow their banks to cause flooding, and sea waters can be pushed towards land by massive winds, which then causes flooding. Rainfalls over an extended period can cause major rivers to overflow their banks. Rivers can overflow their banks, causing flooding during heavy rains, severe storms and dam breaks. Huge amounts of water flowing in rivers are due to incessant heavy rains and melting of snow, resulting in severe flooding. Flash flood normally happens during the monsoon season. Around this time, potholes can overflow fast, breaking and damaging the river banks.
Generally, most flash flooding can be caused by a number of things due to slow-moving thunderstorms or a multiple of thunderstorms moving over the same area. Flash floods often carry away some trees along the river, and these floods can destroy buildings, roads, bridges, etc.
Coastal flooding can result from heavy rains due to cyclones or tropical storms, causing sea water to flow towards inland. Moreover, tsunamis are caused by an underwater earthquake and a volcanic eruption, and these can carry away sampans and motor boats into the sea. Flooding in urban areas can be caused by flash floods, coastal or river floods, but there is also a specific flood type that is called urban flooding.
Urban floods are entirely manmade with poorly maintained drains, plastic bags and trash shrinking free passage for water to flow. Climate change is also a factor in contributing to accumulation of water on roads after a heavy downpour. Coastal flooding can result from a variety of different causes, including storm surges created by hurricanes and tropical cyclones, rising sea levels due to climate change and tsunamis. Man-made floods can be caused by unsystematic cultivation method, poor urban infrastructure, deforestation and growing urban development.
Causes of landslides
A landslide is defined as the movement of a mass of rock, debris or earth down a slope. Landslides are a type of ‘mass wasting,’ which denotes any down-slope movement of soil and rock under the direct influence of gravity.
Almost every landslide has multiple causes. Slope movement occurs when forces acting down-slope exceed the strength of the earth materials that compose the slope. Causes include factors that increase the effects of downward-slope forces and factors that contribute to low or reduced strength. Landslides can be initiated in slopes already on the verge of movement by rainfall, snowmelt, changes in water level, stream erosion, changes in ground water, earthquakes, volcanic activity, disturbances of human activities, or any combination of these factors.
Earthquake movements and other factors can also induce landslides underwater. These landslides are called submarine landslides. Submarine landslides sometimes cause tsunamis that damage coastal areas. Landslides can also be caused on account of heavy rains and instabilities in slopes. Slope movement occurs with forces acting downwards-slope. There are also other factors that cause underwater landslides.
Effects of flash flooding
Flash flooding can have devastating consequences and can have effects on the economy, environment and its people. During floods, especially flash flooding, houses, offices, hospitals, transportation, roads, bridges, water tanks are destroyed. People become homeless. Additionally, the government deploys firemen, police and other emergency apparatuses to the affected areas. It usually takes years for affected communities to be rebuilt and resettle in order to be back to normalcy. The environment also suffers when floods occur. Moreover, chemicals and other hazardous substances end up in water and eventually contaminate the water bodies that floods end up in. In addition, flooding can destroy the natural balance of the ecosystem.
Coping with the aftermaths of flooding
Many people and animals have perished in flash floods and others have been made homeless. Thus, they have to take shelters at the temporary relief centers, schools, halls and monasteries. Flooding brings a lot of diseases and infections including fever, pneumonia and dysentery.
The consequences of events triggered by a flash flooding usually overwhelms local response capacity and seriously affects the social and economic development of the country. As for the authorities concerned, concerted efforts are being made to provide necessary assistance to these flood victims nationwide. The collaboration between governments, NGOs, CSOs and donors plays a pivotal role to fulfill their requirements and to return these regions to a better than normal condition.
Win Ko Ko Aung