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
Nutrient cycling in the Columbia River Basin nitrogen and phosphorus concentrations from eutrophication. The high N/Si and P/Si rations caused by these processes can be harmful to the local ecosystem in the basin; for example, N/Si ratios greater than 1 can result in excess nitrogen relative to diatom requirements, this can promote the growth of other phytoplankton species, negatively affecting diatom communities. This impact of reservoirs on the transport and recycling of silicate, phosphorus, and nitrogen, is not unique to the Columbia River Basin, but has had a measurable impact on the export of these nutrients through the basin and out of the estuary. As discussed in