Question – The increasing number of glacial lakes is a growing concern for flash flood. How can the challenges of flash floods be dealt with? – 4 August 2021
Answer – Glacial lakes is a growing concern for flash flood
- Flash floods are caused by heavy or excessive rainfall, usually in less than 6 hours. They can be caused by extreme rainfall of minutes or even a few hours. They can also occur when there has been no rain, for example, after a levee or dam has failed, or after a sudden release of water from debris or ice water.
- Rainfall intensity, location and distribution of rainfall, land use and topography, vegetation type and growth/density, soil type, and soil moisture, all determine how flash flooding can occur.
- Urban areas are also prone to flooding, with shorter time spans, and sometimes rainfall (from a single storm) in urban areas causes faster and more severe flooding than in suburbs or rural areas. In urban areas, the impermeable surface does not allow water to infiltrate the ground, and the water rushes to very low places.
- Flash flooding happens so quickly that people are surrounded from all sides. If they encounter high, high-speed water while traveling, their situation could be dangerous. If people are in their homes or businesses, water can rise quickly, and trap them, or damage property without a chance to protect the property.
- A flood in northern India, also triggered by a glacier, is not an isolated event, but the result of a rapid warming.
- In regions like the Himalayas, the problem of rising temperatures is threefold: it leads to the melting of mountain glaciers, which can lead to flooding. It also reduces glacial coverage, reducing the long-term availability of water for people, agriculture and hydropower. Finally, as glacier cover decreases, and the area is replaced by water or land, the albedo—the amount of light that reflects off a surface without being absorbed—also decreases. This can absorb solar energy, leading to more warming.
- Glaciers are often referred to as the “water towers” of the world, with half of humanity relying on mountains for their water needs. The Tibetan Plateau alone is the source of the 10 largest rivers in Asia and provides water for 1.35 billion or 20 percent of the world’s people.
- The “World Glacier Monitoring Service”, a Switzerland-based organization that works closely with UNEP, and monitors global glacial change. In the 1960s, its data showed that glaciers were largely stable, but glacial losses have increased rapidly since the 1970s, doubling nearly every decade until the present. This indicates that all this is happening due to climate change.
Adaptation process – Glacial lakes
- In the Paris Agreement, member states have committed to limiting global temperatures to below 2 °C, and preferably 1.5 °C, to pre-industrial levels. Reducing global warming will help save glaciers, but countries will also have to prepare for mountain ecosystems due to the inevitable rise in temperatures. The best way is through adaptation, in other words, introduce a change in the ecosystem that will help counter the effects of global warming.
While ecosystem-based adaptation projects cannot stop glaciers from melting, they can significantly reduce the catastrophic impacts. In addition, they can help mountain communities adapt to a warmer climate, for example by promoting drought-resistant crops.