Ganges Basin (112,490 km²), West Bengal (71,485 km²), Haryana (34,341 km²), Himachal Pradesh (4,317 km²) , Delhi, Arunachal pradesh(1,484 km²), the whole of Bangladesh, Nepal and Bhutan. Several tributaries rise inside Tibet before flowing south through Nepal. The basin has a population of more than 500 million, making it the most populated river basin in the world. The basin comprises semi-arid valleys in the rain shadow north of the Himalaya, densely forested mountains south of the highest ranges, the scrubby Shiwalik foothills and the fertile Gangetic Plains. Central highlands south of the Gangetic Plain have plateaus, hills and mountains intersected by valleys
Mahanadi River Delta with a maximum of 877 m and a minimum of 193 m. The upper part of the delta plain is heavily populated. The population density exceeds 36 people per square kilometre, although moving toward the coast the population density falls. Rainfall comes predominantly from the summer monsoon (June through September). The average annual rainfall in the basin is 1,463 mm. Rainfall is extremely low during the rest of the year, rarely exceeding 30 mm per month. Mahanadi River Delta Mahanadi River Delta in India is a basin of deposit that drains a large land mass of the Indian subcontinent into