Riparian ecohydrology: regulation of water flux from the ground to the atmosphere in the Middle Rio Grande, New Mexico
Riparian ecohydrology: regulation of water flux from the ground to the atmosphere in the Middle Rio Grande, New Mexico
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DOI：
10.1002/hyp.6328
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发表时间：
2006-10
影响因子：
3.2
通讯作者：
J. Cleverly;C. Dahm;J. Thibault;D. McDonnell;Julie E. Allred Coonrod
中科院分区：
文献类型：
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作者：
J. Cleverly;C. Dahm;J. Thibault;D. McDonnell;Julie E. Allred Coonrod
过去十年，美国西南部地区因长期区域干旱而面临水资源减少和森林火灾不断升级的问题。对水资源的竞争性需求需要仔细核算流域的水预算。据信，通过河岸蒸散（ET）流失到大气中的水位居水资源预算消耗的前三分之一。为了更好地管理大型河流系统的枯竭，必须更好地了解河岸蒸散模式。本文概述了新墨西哥州中里奥格兰德 (MRG) 河岸 ET 的生态、水文和大气问题。在 MRG 沿线以原生白杨 (Populus deltoides) 森林和非原生盐杉 (Tamarix chinensis) 灌丛为主的地点，对 ET、地下水位深度和微气象条件进行了长期测量。在超过一周的时间内，地下水和叶面积指数 (LAI) 动态与蒸散率密切相关。在 MRG 的大部分地区，地下水位保持在距地表 3 m 以内，三角松森林的蒸散量不受年度干旱条件的影响。浓密的柽柳灌丛的蒸散量并没有随着地下水深度的增加而下降；相反，随着地下水位每天下降近 7 厘米，ET 增加了 50%，从 6 毫米/天增加到 9 毫米/天。同样，当地下水减少时，红椿灌丛的叶面积指数也增加。去除非本地物种后，也可以控制叶面积指数。当将红椿和非本地俄罗斯橄榄（Elaeagnus angustifolia）从美洲松林下移走时，通过减少蒸散量回收的水量与参考地点测量的蒸散量相比为 26 厘米/年。为了研究与 ET 短期变化的相关性，使用逐步多元线性回归来评估 ET 升高或降低的大气条件。在三角藻为主的地区，蒸散异常与净辐射（Rn）呈正相关，与感热通量（H）、跨廊道风速（v）和沿廊道风速（u）呈负相关（r2 = 0·54）。在红豆杉为主的站点，ET异常与Rn、u、摩擦系数(u*)和水汽压差(VPD)呈正相关，与地表湿度(q*)、日高低温、H和降水量呈负相关(r2 = 0·66)。当条件有利时，柽柳和杨树都能蒸发大量的水。在MRG中，T. chinensis优先出现在夏季洪水和冷空气排水发生的地方，P. deltoides优先出现在距地表2 m以内的浅层地下水区域。版权所有 © 2006 约翰·威利父子有限公司
During the previous decade, the south‐western United States has faced declining water resources and escalating forest fires due to long‐term regional drought. Competing demands for water resources require a careful accounting of the basin water budget. Water lost to the atmosphere through riparian evapotranspiration (ET) is believed to rank in the top third of water budget depletions. To better manage depletions in a large river system, patterns of riparian ET must be better understood. This paper provides a general overview of the ecological, hydrological, and atmospheric issues surrounding riparian ET in the Middle Rio Grande (MRG) of New Mexico. Long‐term measurements of ET, water table depth, and micro‐meteorological conditions have been made at sites dominated by native cottonwood (Populus deltoides) forests and non‐native saltcedar (Tamarix chinensis) thickets along the MRG. Over periods longer than one week, groundwater and leaf area index (LAI) dynamics relate well with ET rates. Evapotranspiration from P. deltoides forests was unaffected by annual drought conditions in much of the MRG where the water table is maintained within 3 m of the surface. Evapotranspiration from a dense Tamarix chinensis thicket did not decline with increasing groundwater depth; instead, ET increased by 50%, from 6 mm/day to 9 mm/day, as the water table receded at nearly 7 cm/day. Leaf area index of the T. chinensis thicket, likewise, increased during groundwater decline. Leaf area index can be manipulated as well following removal of non‐native species. When T. chinensis and non‐native Russian olive (Elaeagnus angustifolia) were removed from a P. deltoides understory, water salvaged through reduced ET was 26 cm/yr in relation to ET measured at reference sites. To investigate correlates to short‐term variations in ET, stepwise multiple linear regression was used to evaluate atmospheric conditions under which ET is elevated or depressed. At the P. deltoides‐dominated sites, ET anomalies were positively correlated to net radiation (Rn) and negatively correlated to sensible heat flux (H), cross‐corridor wind speed (v), and along‐corridor wind speed (u) (r2 = 0·54). At the T. chinensis‐dominated sites, ET anomalies were positively correlated with Rn, u, the friction coefficient (u*), and vapour pressure deficit (VPD) and were negatively correlated to surface humidity scale (q*), daily high and low temperature, H, and precipitation (r2 = 0·66). Both Tamarix and Populus can transpire prodigious quantities of water when conditions are favourable. In the MRG, T. chinensis is preferentially found where summer flooding and cold air drainage occurs, and P. deltoides is preferentially located in areas with shallow groundwater within 2 m of the surface. Copyright © 2006 John Wiley & Sons, Ltd.