Improving flood prevention measures in South Asia
KHILENDRA BASNYAT
Flood is one of the dangerous natural disasters. The damage caused by it in South Asia is increasing, mainly due to rapid urbanization in this region and the concentration of population in flood-prone areas.
Some technicians are of the opinion that the damage caused by flood is increasing with rising sea levels due to global warming and irregular climate changes. However, the Inter-Governmental Panel for Climate Change predicts that global warming would increase rainfall during the monsoon, especially in South Asia. The percentage increase in the quantity of water cannot be so high that every year we would get flood. Therefore, flooding could not be just from much rainfall but from other reasons as well.
Flood occurs when a river reaches its carrying capacity for water. Adequate water can enter into a river through adequate rainfall in short time in river catchments or source areas. Actually, flood occurs in most countries. However, in recent years, there has been frequent occurrence of flood in many countries, which the earth cannot sustain.
Generally, where there is the catchment of rivers, there is forest. When it rains heavily in such a site, forest acts like a sponge delaying the flow of water to the rivers. The stripping of the forest cover in many areas led to soil deposition, which reduces the ability of the land to support an increasing population.
When there is no forest, water rapidly reaches the rivers, increasing the possibility of flood. When there are no roots of the trees to hold the soil, it is flushed into the rivers augmenting its sediments in the river channels. Consequently, the river water carrying capacity further decreases and makes it more prone to overflowing its banks. This is why the risk of flood increases in each monsoon in South Asia.
Rainwater is essential in many countries, where agriculture is the mainstay of the majority of the people. However, since the last few years, there have been frequent devastating floods in these countries. As a result of this, there has been adequate loss of lives and wealth. It is because the destruction of forests that are presented in their natural state is becoming very distressing. In addition, deforestation in the hills causes soil erosion and the extent to which this in turn contributes to flooding on the plains.
Scientists have developed several methods to mitigate flood, of which the construction of dams is the one. Japan, for example, has used dams for flood control and power generation by building a series of dams and reservoirs upstream and then connecting them to a power plant through a waterway channel. By this method the amount of downstream flow from the dams can be managed, thus stabilizing the river ecosystem.
Also, Japan has developed a system of rice cultivation in harmony with its natural water cycle and rich biodiversity. The paddies help to regulate the flow of water downstream, and water takes time to calculate through the paddy system. They protect against flood.
To check flood, embankments along all the vulnerable river stretches should be made. Apart from this, human settlements in catchments areas should be discouraged and a forestation encouraged.
International Flood Network (IF Net) supports worldwide by providing technology and knowledge related to flood. Formally, IF Net took part in the World Water Forum at the suggestion of Japan.
IF Net has three main purposes. The first is to exchange ideas within the network on information technology and future plan as regards flood. The second is to sponsor activities that raise public awareness of flood. Last but not least is to work to promote policy regarding flooding as an international issue that must be addressed as a priority both by governments and concerned institutions. One of IF Net’s projects is the Global Flood Alarm System (GFA), which sends out information about flood worldwide based on data observed from satellites. This will help mitigate flood disaster to some extent.
Most South Asian countries do not possess system allowing ensuring rainfall in right time. If these countries use GFA, it will help them to improve their advance flood preventive measures.