黄河三角洲造陆速率对夏季风强度变化和人类活动的响应

以夏季风强度指数和年均气温作为反映气候变化的指数,以人类净引水量和流域水土保持面积作为反映人类活动变化的指标,并以黄河流域为例,研究了三角洲造陆对气候变化和人类活动的响应.研究表明,夏季风强度指数的变化可分为三个阶段:(1)在1951~1963年夏季风强度指数呈持续增强的变化趋势;(2)在1963~1965年夏季风强度指数呈突变式减弱;(3)在1966~2000年夏季风强度指数保持在较低的水平上,且呈缓慢减弱的趋势.年降水量变化与夏季风强度指数有同步关系.从1950到1970年的年均温度在波动中略呈降低趋势,然而从1970年开始年均温度在波动中具有持续上升的趋势.气候变化会导致入海泥沙通量的变化,并可能进一步导致三角洲造陆速率的变化.黄河三角洲造陆速率、入海泥沙通量在1952~1964年均呈增大的趋势,1964年后则呈减小的趋势,在总体上与夏季风强度指数的变化趋势相同.除了气候变化以外,流域水土保持和引水对三角洲造陆也有影响.多元回归分析表明,三角洲造陆速率随夏季风强度指数的减弱而减小,随年气温的升高而减小,随梯田林草面积的增加而减小,随年净引水量的增加而减小,同时还表明,夏季风强度指数、年均气温、水土保持措施面积和人类净引水量对三角洲造陆速率变化的贡献率分别为34.94%,3.80%,53.82%和7.44%.表示气候变化的两个变量的贡献率之和为38.7%,说明气候变化对黄河三角洲造陆过程的影响是不容忽视的.

Response of land accretion of the Huanghe River Delta to global climate change and human activity

In the past 50 a,the East Asian summer monsoon intensity index has changed significantly,which has led to some response to the water cycle system of the Huanghe River Basin.The variation of the summer monsoon intensity index shows three stages:(1) from 1951 to 1963,the summer monsoon intensity index increased;(2) from 1963 to 1965,the summer monsoon intesity declined sharply,which may be regarded as an abrupt change;(3) from 1965 to 2000,the summer monsoon intensity index remained at low levels and showed a decreasing trend.The variation of annual precipitation is synchronic with that in the summer monsoon intensity index.From 1950 to 1970,annual air temperature showed slight decrease in large fluctuations.From 1970,a significant increasing trend can be seen.Climate change may result in a change in sediment flux into the sea,and therefore a change in the rate of land accretion of the delta.The annual rate of land accretion of delta and sediment flux into the sea tended to increase from 1952 to 1964,but decreased after 1964,its tendency was similar to the summer monsoon intensity index.Apart from the climate factor,human activity such as water and soil conservation measures and water division in the drainage basin also have some effect on land accretion of the Huanghe River Delta.A multiple regression analysis indicates that the rate of land accretion of the delta decreased with the decrease in the summer monsoon intensity index,the increase in annual temperature,the increase in the area of water and soil conservation measures and increase in water diversion.The contribution of the variations of the above influencing variables to the variation of the rate of land accretion of the delta was calculated as 34.94%,3.80%,53.82% and 7.44%,respectively.The contribution of the two climate factors sums 38.7%,indicating that the influence of global climate change on the variation in the land accretion of the Huanghe River Delta is significant.