Water scarcity has become one major obstacle for sustained economical and social development in China.The main focus of this study is analyzing causes of water scarcity.From the perspective of water supply,there are drought-induced water scarcity,pollution-induced water scarcity and engineering-induced water scarcity.From the perspective of water demand,there are configuration-induced water scarcity,efficiency-induced water scarcity and price-induced water scarcity.To reduce water scarcity,passive,active and mixed water resource allocations are proposed.