Contrasting mechanisms of salt delivery to the stream from three different landforms in South Eastern Australia
Contrasting mechanisms of salt delivery to the stream from three different landforms in South Eastern Australia
复制标题
澳大利亚东南部三种不同地貌向河流输送盐分的机制对比
DOI：
10.1016/j.jhydrol.2006.05.002
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发表时间：
2006
影响因子：
6.4
通讯作者：
F. Leaney
中科院分区：
文献类型：
--
作者：
G. Summerell;N. Tuteja;R. Grayson;P. Hairsine;F. Leaney
本研究探讨了澳大利亚东南部干旱地区盐和水从景观到主要地貌流的运动途径。该研究是在澳大利亚新南威尔士州Kyeamba流域的一个子流域Livingstone Creek流域（143平方公里）进行的。2002年至2004年，在主要地貌之间建立了一个广泛的溪流盐度实地监测网络，并收集了数据。还对地表水同位素进行了额外测量，以独立评估从详细监测网络观察到的反应，并协助确定水源。流量和盐质量平衡计算了四个测量站的每个事件。溪流监测发现，在四个监测的溪流事件期间，向溪流输送盐的模式是一致的。在山坡和崩积填充，较低的倾斜，变质沉积物地貌，流盐度的响应显示了经典的盐度响应的事件：初始增加的盐度在一个事件的开始（由于第一次冲洗），然后减少稀释的结果。这些地貌之间的主要区别是，崩积物填充较低的倾斜变沉积物的含钠，低渗透性土壤附近的流边缘。这导致（1）事件条件下河流盐度的变化较小，（2）低基流期间，由于河岸的浓缩盐溶解，河流盐度增加。对于平坦的冲积地貌，盐度的响应表现出相当不同的和对比鲜明的时间模式：盐度继续增加，并直接随流量变化的事件。对于所有的地貌，基流盐度增加，流量减少后，事件虽然盐度的响应更加滞后的冲积地貌。冲积地貌中这种不同的盐度模式归因于：（1）对于事件流，来自冲积地貌的土壤水的含盐量更高的地下侧流的贡献比来自上游山坡地貌的非常新鲜的直接地表径流的贡献更大;（2）对于基流，邻近河流的冲积地下水通过河岸渗漏，其含盐量低于来自山坡地貌上游的基流水。河水同位素值证实了上述研究结果表明，在冲积地貌土壤水的贡献是重要的事件期间，直接地表径流与土壤水的相互作用很小，发生在事件期间的山坡地貌。通过不同的地形和不同的前期集水区湿度条件下描述盐和水的运动的概念模型。这些概念模型发展了我们对水和溶质（盐）通过景观到溪流的路径的理解。迄今为止，这是澳大利亚为数不多的连接景观和溪流盐碱化的实验研究之一。
This study explores the pathways of salt and water movement from the landscape to the stream across major landforms, in dryland areas of south eastern Australia. It was conducted at the Livingstone Creek catchment (∼43km2) a sub catchment of the Kyeamba catchment, NSW, Australia. An extensive stream salinity field monitoring network between major landforms was developed and data capture occurred from 2002 to 2004. Additional measurements of surface water isotopes were also taken to independently assess responses observed from the detailed monitoring network and assist in determining the sources of water. Flow and salt mass balances were calculated across four gauging stations for each event. The stream monitoring found patterns of salt delivery to streams were consistent during four monitored stream events. In the hill slope and colluvial fill, lower sloped, meta-sediment landforms, stream salinity responses showed the classical salinity response to an event: an initial increase of salinity at the beginning of an event (due to first flush) which then diminished as a consequence of dilution. The main difference between these landforms was that the colluvial fill lower sloped meta-sediments had sodic, low permeability soils near the stream edge. This lead to (1) less variation in stream salinities during event conditions and (2) during low base flow increases in stream salinity occurred as concentrated salts from the stream banks dissolved. For the flatter, alluvial landforms, the salinity response showed quite a different and contrasting temporal pattern: salinity continued to increase and vary directly with flow during events. For all the landforms, base flow salinity increases as flow diminished after a event although salinity responses were more lagged in the alluvial landform. This different salinity pattern in the alluvial landform is attributed to (1) for event flow, the increased contributions of more saline subsurface lateral flow of soil water from the alluvial landform compared to very fresh direct surface runoff sourced from hillslope landforms upstream and (2) for base flow, seepage of near stream alluvial groundwater through the stream banks that was less saline then the base flow water sourced upstream from the hillslope landforms. The stream water isotope values confirm the above findings by showing that, in the alluvial landforms soil water contributions are important during events and that direct surface runoff with little interaction of soil water occurs from the hill slope landforms during events. Conceptual models describing salt and water movement through the different landforms and under different antecedent catchment wetness conditions are presented. These conceptual models develop our understanding of water and solute (salt) pathways through the landscape to the stream. To date, this is one of the few experimental studies in Australia connecting landscape and stream salinisation.