The quality of life in Bangladesh is low, as both the population density and the death rate are high, and both Life expectancy and adult literacy are low.
The land in the Delta (towards the Bay of Bengal) is vastly used for arable crops, as it is so fertile and flat. Most people in Bangladesh earn their living through farming, so they have to grow lots of food. The silt in the delta was eroded by the surface runoff picking up soil from fields, and by abrasion of the riverbed. It is transported by the sea waves, and by longshore drift.
The flooding in Bangladesh is due mainly to the low-lying, flat ground, which makes the water spread out easily. The drainage density is high, so there is lots of water to create a flood, and coastal cyclones can sweep across the low-lying coast. The river discharge is often low between January and July, and then increases rapidly between June and August (to a peak of 45000 cumecs), and dropping from September to November. The peak discharge occurs one month after peak rainfall, because there is a time lag due to soil and other stores intercepting the water flow. It also takes a long time for rain to get downstream.
The foothills of the Himalayan Mountains are heavily forested. In recent years large areas of forest have been cut down. Farmers then grow crops to feed the increasing population. This creates many problems, as the trees delay the water running down the Mountain so that there is more time for evaporation to take place. This is helpful because it reduces the flood risk towards the houses situated on the land below. Without these trees, the water run-off has no interception and will flow towards the lowland and lead to increased drainage, which leads to flooding.
The rainfall in India and Nepal is very important to Bangladesh, as it flows down into Bangladesh and could destroy their crops. It also provides fresh water for drinking. This is proved when we look at the total annual rainfall for all three countries. At 2000mm (500mm less than Northern India and 1000mm less than Nepal), we can see that the main problem springs from the water flowing down from the surrounding countries.