长江下游流域第四纪古年地表径流量的估算——一种第四纪古水文学研究方法的应用尝试

ESTIMATING ANNUAL RUNOFF OF QUATERNARY PAST FOR THE DOWNSTREAM CATCHMENT OF YANGTZE RIVER: AN APPLICATION OF AN APPROACH TO QUATERNARY PALAEOHYDROLOGY

利用以现代数据建立的年平均温度和年平均地表降水量-年平均地表径流量关系式以及古年温度值和古年降水量值,估算了位于长江下游流域的镇江、太湖、上海地区的晚更新世寒冷期以来不同地质时代的古年地表径流量值。结果表明,长江下游流域年地表径流量在晚更新世寒冷期较现代少约95—60％;在全新世早期由较现代少约34％至多约55％,而在全新世中期则很可能约为现代的1.2—3.3倍。

One of the approaches to Quaternary palaeohydrology is to estimate the runoff values of Quaternary past from the corresponding Quaternary palaeotemperature and palaeoprecipitation information using the relationships between temperature, precipitation and runoff established with the climatological and hydrological data of the contemporary time. This paper deals briefly with this approach and especially its application in the palaeohydrological reconstruction for the downstream catchment of Yangtze River. Palaeoclimatic information is first collected for the Zhenjiang area, the area around Taihu Lake and Shanghai area within the region under study, i.e. the downstream catchment of Yangtze River. Then the past values of temperature and precipitation of the late Pleistocene's cold stage and Holocene are estimated for the three areas by evaluating the palaeoclimatic information acquired and investigating today's climate of China. Using these palaeotemperature and palaeoprecipitation estimates and the relationships between mean annual temperature, mean annual precipitation and mean annual runoff derived previously with modern data, palaeorunoff values of the late Pleistocene's cold stage, early and middle Holocene are calculated for the three areas. The calculations indicate that in the downstream catchment of Yangtze River, the annual runoff of the late Pleistocene's cold stage could be from 95% to 60% less than its present equivalence; the annual runoff was from 34% less to 55% more than it is now during the early Holocene; and it might be 1.2—3.3 times as much as the contemporary runoff during the middle Holocene.