五道沟试验场降雨径流中的氢氧稳定同位素特征分析

在淮北平原区五道沟水文水资源试验场,对降雨径流中的氢氧稳定同位素组成变化的特点及控制平原区河道径流组分划分的一些流域水文因素进行了同位素示踪实验研究.结果表明,实验期间降雨中的δ(18O)(-0.918%～-0.518%)及δ(2H)(-5.064%～-2.310%)的变幅较大,并随雨强的降低而增大;1,3,6号测井地下水的δ(18O)(或δ(2H))主要与补给区水源及降雨的δ(18O)(或δ(2H))有关,其对降雨入渗补给的响应较慢,有明显的滞后效应;IR自记井及S4抽水井由于受抽水灌溉等人类活动的持续影响,δ(18O)(或δ(2H))明显偏负,表明有来自深部潜水的补给.此外,流域出口断面河水的δ(18O)(或δ(2H))受平原型流域较强均化作用的影响,其变幅远远小于降雨的δ(18O)(或δ(2H))变幅,在使用同位素方法划分河道径流组分时,需要考虑降雨到形成河道径流的传输时间.

Characteristics of stable hydrogen and oxygen isotopes of precipitation and runoff in Wudaogou Hydrological Experimental Catchment

The characteristics of stable hydrogen and oxygen isotopes of precipitation-runoff components and some factors controlling the partitioning of different water sources of streamflows were investigated for a precipitation event in the Wudaogou Hydrological Experimental Catchment on the Huaibei Plain of China. The analytic results show that the values of the isotopic composition δ(~(18)O)( -0.918% ～ -0.518%) and δ(～２H)( -5.064% ～ -2.310%) of precipitation have large ranges of variation, and increase with the decrease of the precipitation intensity. The values of δ(~(18)O) (or δ(~2H)) forgroundwater from holes 1, 3 and 6 mainly relate to those of δ(~(18)O) (or δ(~2H)) for the groundwater recharge sources and precipitation in the area. They show a slow response to the precipitation infiltration and there exists a time lag effect. Well IR and pumping well S4 have been continuously influenced by human activities such as pumping and irrigation. The values of δ(~(18)O) (or δ(~2H)) are relatively negative, indicating the recharge of deep groundwater. In addition, the values of δ(~(18)O) (δ(~2H)) of river water at the outlet have a smaller range of variation than those of the precipitation owing to the homogenization of the plain-type catchment. It is suggested that the transfer time for the precipitation to form the streamflow should be considered in the application of isotopic methods to divide components of streamflow.