Bangladesh is a low-lying, riverine country located in South Asia with a largely marshy jungle coastline of 710 km on the northern littoral of the Bay of Bengal. Formed by a delta plain at the confluence of the Padma, Jamuna, and Meghna Rivers and their tributaries, Bangladesh’s alluvial soil is highly fertile, but vulnerable to flood and drought. Hills rise above the plain only in the Chittagong Hill Tracts in the far southeast and the Sylhet division in the northeast. Straddling the Tropic of Cancer, Bangladesh has a tropical monsoon climate characterized by heavy seasonal rainfall, high temperatures, and high humidity. Natural disasters, such as floods, tornadoes, and tidal bores affect the country yearly. Bangladesh also is affected by major cyclones, on average 16 times a decade.