the damage to water conservation areas was concentrated in the upstream source, less than 60 km in a
straight line from Deyang, Shifang and Mianzhu cities. The damaged areas of the Minjiang River basin
were located 15 km from Dujiangyan city and 80 km from Chendu city (the capital of Sichuan province).
Thus the impact of the loss of the water conservation function in the study area threatened cities
downstream, and also the safety of the water supply for the entire Chengdu Plain.
The reduction of the soil conservation function, in order from high to low, were the Minjiang,
Tuojiang, Fujiang and Jialing Rivers. In the Minjiang basin, the areas that suffered major soil
conservation function damage were the Zipingpu Reservoir in northern Dujiang city, and the Longxi–
Hongkou National Nature Reserve. Severely damaged soil conservation functions in these regions posed
the greatest risk to the Zipingpu Reservoir, threatening the safety of the water supply in areas downstream
of the reservoir.
The three areas in which the carbon conservation function was most seriously compromised by the
earthquake were the Minjiang River (reduced by up to 500 106 t), Tuojiang River (reduced by
3.47 106 t) and Fujiang River (reduced by 1.37 106 t).