Isotope hydrology of the Oldman River basin, southern Alberta, Canada
Isotope hydrology of the Oldman River basin, southern Alberta, Canada
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DOI：
10.1002/hyp.6545
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发表时间：
2007-11
影响因子：
3.2
通讯作者：
L. Rock;B. Mayer
中科院分区：
文献类型：
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作者：
L. Rock;B. Mayer
部分半干旱的奥德曼河流域（OMRB）位于加拿大阿尔伯塔省南部，面积28200平方公里，其西部水源部分为森林，东部为农业。水文测量表明，奥德曼河的流量在1913年至2003年期间减少了1.34%，预计在未来20年内取水量将增加。本研究的目的是确定是否同位素比测量可以提供进一步了解奥德曼河及其支流的水动力学。2000年12月至2003年3月，每月采集地表水样本。在一次采样行程中，从58口威尔斯井中采集了地下水样本。目前，OMRB内的径流量约为70 mm年-1，相应的径流率为0.18。奥德曼河水库上游和下游的季节性水流特征明显不同。上游，在春末夏初流量急剧增加，随后迅速下降到基本流量水平。下游，由于奥德曼河水库的蓄水效应，观察到长时间的高流量峰值。来自上游站点的地表水的同位素组成的季节性变化很小。这表明，峰值径流主要不是由前一个冬天积累的积雪融化产生的，而是主要由相对混合良好的年轻地下水产生的。在盆地的下游部分观察到δ 18 O和δ 2 H值的显著增加。同位素值的增加部分是由于地表水和地下水的流入，东部的δ 18 O和δ 2 H值逐渐升高，部分是由于蒸发。因此，水文数据与同位素测量相结合，对OMRB的水动力学产生了有价值的见解，未来可以通过更密集的测量方案进一步完善。版权所有© 2006约翰威利父子有限公司。
The partially semi‐arid Oldman River basin (OMRB), located in southern Alberta (Canada), has an area of 28 200 km2, is forested in its western headwater part, and is used for agriculture in its eastern part. Hydrometric measurements indicate that flow in the Oldman River has decreased by ∼34% between 1913 and 2003, and it is predicted that water withdrawals will increase in the next 20 years. The objective of this study was to determine whether isotope ratio measurements can provide further insight into the water dynamics of the Oldman River and its tributaries. Surface water samples were collected monthly between December 2000 and March 2003. Groundwater samples were taken from 58 wells during one‐time sampling trips. Runoff within the OMRB is currently about 70 mm year−1, with a corresponding runoff ratio of 0·18. Seasonal flow characteristics are markedly different upstream and downstream of the Oldman River reservoir. Upstream, sharp increases in flow in late spring and early summer are followed by a rapid decrease to base flow levels. Downstream, a prolonged high flow peak is observed due to the storage effect of the Oldman River reservoir. The seasonal variation in the isotopic composition of surface water from upstream sites is small. This suggests that peak runoff is not predominantly generated by melting snow accumulated during the preceding winter, but mainly by relatively well‐mixed young groundwater. A significant increase in the δ18O and δ2H values in the downstream part of the basin was observed. The increase in the isotopic values is partly due to surface water and groundwater influx with progressively higher δ18O and δ2H values in the eastern part, and partly due to evaporation. Hence, the combination of hydrometric data with isotope measurements yields valuable insights into the water dynamics in the OMRB that may be further refined with more intensive measurement programmes in the future. Copyright © 2006 John Wiley & Sons, Ltd.