The identification of runoff‐production mechanisms using environmental isotopes in a tussock grassland catchment, eastern otago, New Zealand
The identification of runoff‐production mechanisms using environmental isotopes in a tussock grassland catchment, eastern otago, New Zealand
复制标题
使用环境同位素识别新西兰东部奥塔哥草丛草原流域的径流产生机制
DOI：
--
复制
发表时间：
1990
期刊：
影响因子：
--
通讯作者：
M. Stewart
中科院分区：
文献类型：
--
作者：
M. Bonell;A. Pearce;M. Stewart
先前对新西兰奥塔哥（45°50′S，169°45′E）草丛草地流域产流的水文测量研究表明，在风暴过程线衰退中，坡度发生了显著变化。一项环境同位素研究开始调查径流机制的运作，并测试具体的假设，以解释这一突破的过程线衰退。结果表明，对于急流量超过10毫米，第一部分的暴雨过程线可以归因于两个独立的来源，即，“老”水从浅，无压地下水库和“新”水从饱和坡面流在较低的湿地凹坡。尽管湿地面积广阔，“老”的水径流从无压地下水库更迅速地传递到流比“新”的水从饱和地表径流。在雨水成为河流排放的重要组成部分之前，必须首先超过湿地的大量表面储存。对于小于10 mm的速流量，只有地下水中的“老”水对过程线衰退的第一部分有贡献。这意味着，只有最大的7%的风暴（就快速流量而言）产生包含大量“新水”的快速流量。第二部分的衰退的风暴过程线由“老”水来自一个非常好的混合浅无压地下水体。
A previous hydrometric study of runoff production in tussock grassland drainage basins in Otago (45°50′S, 169°45′E), New Zealand, revealed a marked change of slope in storm hydrograph recessions. An environmental isotope study was initiated to investigate the runoff mechanisms operating and to test specific hypotheses to explain this break in the hydrograph recession. The results indicated that for quickflow volumes in excess of 10mm, the first part of the storm hydrograph can be attributed to two separate sources, namely, ‘old’ water from a shallow, unconfined groundwater reservoir and ‘new’ water from saturation overland flow on the lower wetlands of concave slopes. Despite the extensive area of wetlands, ‘old’ water runoff from the unconfined groundwater reservoir is delivered more rapidly to the stream than ‘new’ water from saturation overland flow. Substantial surface storage in the wetlands has first to be exceeded before rain becomes a significant part of stream discharge. For quickflow volumes less than 10mm, only ‘old’ water from groundwater contributes to the first part of the hydrograph recession. This means that only the largest 7 per cent of storms (in terms of quickflow volume) generate quickflow containing significant amounts of ‘new water’. The second part of the recession of the storm hydrograph consists of ‘old’ water derived from a remarkably well-mixed shallow unconfined groundwater body.