Impacts of human activity on river runoff in the northern area of China

The following basins in the northern area of China are selected as the case study areas: the Yellow River, the Haihe River, the Liaohe River, and the Songhuajiang River. Qualitative and quantitative analyses of the impact of human activity on river runoff in different spatio-temporal scales, including daily, monthly, annual, inter-decade, inter-century variations, according to long-term observation data, are carried out. The driving forces of annual runoff change in those rivers are also analyzed. It can be seen from observed data that the quantity of downstream flow in the northern part of China depends on precipitation over a catchment and withdrawal from the upstream. River runoff has a tendency towards decrease in terms of a natural basin as well as in terms of an administrative region. Besides the climatic changes, the increase in the amount of water taken from river course is the direct cause why observed runoff decreases in the northern part of China. The frequency, at which minor daily discharge appears, increases rapidly. Annual mean runoff generated from the same order of precipitation in 1980s and 1990s decreases by 20–50% as compared in 1950s and 1960s. The impact of human activity on river discharge is more in arid or semi-arid areas than in humid areas.