Combined use of isotopic and hydrometric data to conceptualize ecohydrological processes in a high‐elevation tropical ecosystem
Combined use of isotopic and hydrometric data to conceptualize ecohydrological processes in a high‐elevation tropical ecosystem
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结合使用同位素和水文测量数据来概念化高海拔热带生态系统中的生态水文过程
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发表时间：
2016
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通讯作者：
P. Crespo
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作者：
G. Mosquera;R. Célleri;P. Lazo;K. Vaché;S. Perakis;P. Crespo
全世界很少有高海拔热带流域进行测量，使用水文和同位素数据进行研究的就更少了。因此，我们缺乏所需的信息来了解的过程中，管理流域径流动态和预测其对下游生态系统功能的影响。为了满足这一需求，我们提出了一个组合的水文和水稳定同位素观测在潮湿的安第斯páramo生态系统的Zhurucay生态水文观测站（7.53平方公里）。该流域位于厄瓜多尔南部的安第斯山脉，海拔3400至3900米。在2年期间（2011年5月至2013年5月）收集了用于稳定同位素分析的水样，而自2010年底以来一直记录降雨量和径流量。同位素数据表明，主要位于山坡上的土壤干土排水横向的histosols（安第斯páramo湿地）主要位于谷底。反过来，组织土全年为小溪和小河供水，在湿地和排水网络之间建立水文连通性。径流主要由事件发生前储存在组织土中的水组成，这些水由渗透通过土的降雨补充。矿物层和断裂基岩顶部的贡献很小，似乎仅在低流量生成期间影响小集水区的流量（非渗透流量< Q35）。源贡献的变化受前期土壤湿度、降雨强度和雨季持续时间的控制。土壤的饱和导水率高于全年低降水强度，表明Hortonian坡面流在高强度降水事件中很少发生。深层地下水对排放的贡献似乎微乎其微。这些结果表明，在这个高海拔的热带生态系统中，（1）地下径流是一个占主导地位的水文过程，（2）（硬土）湿地是径流的主要来源。我们的研究强调，在短时间内详细的同位素表征提供了宝贵的信息，生态水文过程中的地区，很少有流域测量。版权所有© 2016约翰威利父子有限公司.
Few high‐elevation tropical catchments worldwide are gauged, and even fewer are studied using combined hydrometric and isotopic data. Consequently, we lack information needed to understand processes governing rainfall–runoff dynamics and to predict their influence on downstream ecosystem functioning. To address this need, we present a combination of hydrometric and water stable isotopic observations in the wet Andean páramo ecosystem of the Zhurucay Ecohydrological Observatory (7.53 km2). The catchment is located in the Andes of south Ecuador between 3400 and 3900 m a.s.l. Water samples for stable isotopic analysis were collected during 2 years (May 2011–May 2013), while rainfall and runoff measurements were continuously recorded since late 2010. The isotopic data reveal that andosol soils predominantly situated on hillslopes drain laterally to histosols (Andean páramo wetlands) mainly located at the valley bottom. Histosols, in turn, feed water to creeks and small rivers throughout the year, establishing hydrologic connectivity between wetlands and the drainage network. Runoff is primarily composed of pre‐event water stored in the histosols, which is replenished by rainfall that infiltrates through the andosols. Contributions from the mineral horizon and the top of the fractured bedrock are small and only seem to influence discharge in small catchments during low flow generation (non‐exceedance flows < Q35). Variations in source contributions are controlled by antecedent soil moisture, rainfall intensity, and duration of rainy periods. Saturated hydraulic conductivity of the soils, higher than the year‐round low precipitation intensity, indicates that Hortonian overland flow rarely occurs during high‐intensity precipitation events. Deep groundwater contributions to discharge seem to be minimal. These results suggest that, in this high‐elevation tropical ecosystem, (1) subsurface flow is a dominant hydrological process and (2) (histosols) wetlands are the major source of stream runoff. Our study highlights that detailed isotopic characterization during short time periods provides valuable information about ecohydrological processes in regions where very few basins are gauged. Copyright © 2016 John Wiley & Sons, Ltd.