There are many reasons for the flooding. We can divide them into two categories. In the first group we have natural causes like high rainfall, snowmelt, relief (in low-lying areas rivers flow very slowly and so the water volume increases suddenly) and coastal flooding because of high tides. In the second group we have human causes which include deforestation, poor farming (over-grazing, over-cultivation, etc. which makes the top soil washed away), poor water management and population pressure. All these factors can be found in India, China and Bangladesh.
