现代降水量与地表径流量间的简明关系和第四纪古水文学

应用以现代数据绘制的某些特定气候状况下的年平均降水量－年平均地表径流量关系曲线并根据已知的古气候状况,推测相应的古地表径流状况,是较为新颖的第四纪古水文学研究方法之一。进一步探究较大空间范围内和较长时间间隔中各种气候状况下的地表径流的变化规律,对于完善和精化这一研究方法颇具意义。利用分布在美国、澳大利亚、津巴布韦和芬兰的七百余个流水盆地的资料和数据,绘制了若干年平均降水量－年平均地表径流量关系曲线,讨论了年平均温度、年平均降水量、气候类型及与之相关的年降水的季节性分布对年平均地表径流量的影响,提出了在第四纪古水文学研究中应用这些关系曲线的事项。

SIMPLIFIED RELATIONSHIPS BETWEEN MODERN PRECIPITATION AND RUNOFF AND QUATERNARY PALAEOHYDROLOGY

A quite new approach to Quaternary palaeohydrology is to reconstruct thepaleorunoff regime from palaeoclimate information available and curves relating meanannual precipitation to mean annual runoff prepared with contemporary data under agiven climate situation. To collect and use contemporary data for larger spatial andtemporal spans and under different climate situations is of significance for improvingthis approach. For this reason, curves relating the mean annual precipitation to themean annual runoff were prepared with data from more than 700 drainage basins inthe United States, Australia, Zimbabwe and Finland. They have been called UScurves, Australia curves, Zimbabwe curves, Finland curves, respectively. There are"Global" curves else that have been prepared with a synthetic set composed of thedata from the four countrics. Use of these curves can contribute to under stand theQuaternary palaeohydrologic situation.Relationships between mean annual 'temperature, mean annual precipitation andmean annual runoff for different climatic conditions are further analysed bycomparing some of these curves each other and checking the data from which thesecurves are prepared, which implies the complexity of climates affecting runoff regime s.Under the same types of climate or when the seasonal distributions of precipitation throughout the year are the same, mean annual runoff increases with the increase of mean annual precipitation if mean annual temperature is constant and decreases with the increase of mean annual temperature if mean annual precipitation isconstant.When climatic types and particularly the seasonal distributions of precipitationthroughout the year associated with the corresponding climatic types are different,then even for the same mean annual temperature and mean annual precipitation,mean annual runoff may still differ.When mean annual temperature and mean annual precipitation are the same,the more seasonal the distribution of precipitation throughout the year is, the moremean annual runoff occurs.Under tropical monsoon climate, tropical rainforest climate, and tropical wetand dry climate with which annual precipitation predominantly occurs in summer orin wet season, values of mean annual runoff, although mean annual temperature isquite high, may still be relatively big and sometimes even bigger than the corresponding values of mean annual runoff for the relatively well-distributed precipitationthroughout the year and the lower mean annual temperature.Under west coastal dry subtropical climate or mediterranean subtropical climatewith which annual precipitation predominantly occurs in winter, values of meanannual runoff may be bigger than the corresponding values of mean annual runofffor the same mean annual temperature and mean annual precipitation when precipitation is relatively well-distributed throughout the year.Under humid continental climate and marine west coast climate with whichprecipitation is relatively well distributed throughout the year, values of mean annual runoff may be very close each other for the same mean annual temperature especially for the value of 15.6℃(60°F) and the same mean annual precipitation.Climatic characteristics including mean annual temperature, mean annual precipitation, climatic types and seasonal distributions of precipitation distinguishing thedrainage basins for which the data are used in preparing each of the curves areexpressed as the "applicable circumstances" for each corresponding curve.A few points on applying these curves in palaeohydrological studies are alsoelucidated.When this approach is used in palaeohydrological cafe studies, the curve(s)whose "applicable circumstances" are the most similar to the climates affecting thestudy region during ancient Quaternary should be chosen to utilize. Therefore, forthe specific study region concerned, it is necessary to reconstruct not only the pastmean annual temperature and past mean annual precipitation but also the palaeoclimatic type and particularly the seasonal distribution of past annual precipitationassociating