Explanation:
postive:
-flood control- the flood storage capacity of three gorges dam reservoir is 22 cubic meters and this capacity can reduce the frequency of major downstream flooding from once every ten years to once every 100 years
negative:
-water pollution- along with the river flowing there is a large number of land experiencing erosion which lead to tons of sands and pepples into he Yangtze river and stay at the upstream and makes great water pollution about Yangtze river
