一、人口变化趋势与用水功能单元分类１.分区与人口。假设未来几十年我国人口的峰值在１６～１７亿之间 ,取其中值为１６.５亿人。１９４９～１９９８年 ,我国北方（１５省区市）的人口比重稳定在４２%左右 ;为此 ,不妨设这一比重在未来５０年略有增长 ,达到４３%左右。如此 ,? First, demographic trends and water functional unit classification 1. Zoning and population. Suppose the peak of our population in the next few decades will be between 1.6 and 1.7 billion, whichever is 1.65 billion. From 1949 to 1998, the proportion of the population in the northern part of China (15 provinces, autonomous regions and municipalities) remained stable at about 42%. For this reason, we can expect this proportion to increase slightly by 43% in the next 50 years. in this way ,?