应用环境同位素技术研究华北典型流域水循环机理的展望

华北水问题日益严重,而水循环机理研究尚显得薄弱。环境同位素水文学是研究流域水循环过程变化的新的技术途径。它利用水中水分子所含的同位素含量的变化,可以判断大气降水的水蒸气的来源;定量分析坡地的产汇流产生机制,进而研究"大气降水—地表水—土壤水—地下水"的相互作用关系;彻底查明流域"四水"转化关系,创新和发展水循环模式。本文主要介绍同位素技术的原理及其在日本、斯里兰卡、河北平原等地应用实例,最后,对应用此技术研究华北典型流域水循环,从"大气—土壤—植被"界面水循环机理、坡地径流的产汇流机制、流域水循环机理等方面进行了展望。

The Prospect in the Research of Water Cycle at the Typical Catchments of North China Plain Using Environmental Isotopes

The water problems in North China plain are very serious, and they hinder the economic development. The reason is that the research of water cycle is not enough. Environmental isotopes have become integral components of hydrological research and applications. They routinely contribute to such investigations, complementing geochemistry and physical hydrology. The environmental isotopic technology is the most powerful tool for hydrological research. For instance, the stable isotopic composition of water is modified by meteoric processes and so the recharge waters in particular environment will have a characteristic isotopic signature. This signature then serves as a nature tracer for the provenance of waters; on other hand, radioisotopes decay provides us with a measure of circulation time, thus groundwater renewability. The source of vapor, which forms precipitation, the mechanism of rainfall and runoff at the slope, the relation among precipitation surface water soil water groundwater, groundwater quality evolution and recharge processes can be understood. In this paper, the stable isotopes (D and O 18) and the radioisotopes (T and C 14) are explained, and their basics, usages and some examples in Japan and China are also introduced. Lastly, the prospect in the research of water cycle at the typical catchments of North China Plain using environmental isotopes is described, including three parts: the system of "atmosphere soil vegetation"at small scale; rainfall and runoff at the slope; water cycle at catchment scale.