Estimating discharge of shallow groundwater by transpiration from greasewood in the Northern Great Basin
Estimating discharge of shallow groundwater by transpiration from greasewood in the Northern Great Basin
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DOI：
10.1029/93wr00930
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发表时间：
1993-08
影响因子：
5.4
通讯作者：
W. Nichols
中科院分区：
文献类型：
--
作者：
W. Nichols
裸露土壤和高位芽植物的蒸散是美国中西部和西部干旱和半干旱地区(包括大盆地)地下水排放的主要机制。对来自降水的地下水补给量的独立估计与根据对地下水蒸散量估计的地下水排泄量之间的不平衡导致地下水预算存在很大的不确定性。很少有研究解决这个问题。能量收支微气象野外研究是1989年夏季在大盆地西部浅层地下水地区生长的疏林油料林中进行的。用能量收支-鲍文比法计算了冠层以上的感热和潜热通量。利用计算的能量收支通量，结合土壤表面和植物冠层温度的测量，校准和应用了一个双组分能量组合模型，该模型分配了裸土和冠层之间的能量和热通量。这使得蒸发从土壤中分离出来，蒸腾从油木中分离出来。用校正后的模型估算了水深约2m的油料林对地下水的日蒸腾作用，估算了7~8月间地下水蒸腾的日排泄量为2.4 mm。假设以这种速度排出地下水的时间为100天，估计研究地点的地下水年排泄量为24厘米。
Evapotranspiration from bare soil and phreatophytes is a principal mechanism of groundwater discharge in arid and semiarid regions of the midwestern and western United States including the Great Basin. The imbalance between independent estimates of groundwater recharge from precipitation and of groundwater discharge based on estimates of groundwater evapotranspiration leads to large uncertainties in groundwater budgets. Few studies have addressed this problem. Energy budget micrometeorological field studies were conducted in a stand of sparse-canopy greasewood growing in an area of shallow groundwater in the western Great Basin during the summer of 1989. The data were used to calculate above-canopy fluxes of sensible and latent heat using the energy budget-Bowen ratio method. The calculated energy budget fluxes were used, with soil surface and plant canopy temperature measurements, to calibrate and apply a two-component, energy-combination model that partitions the energy and heat fluxes between bare soil and the canopy. This permitted the separation of evaporation from the soil and transpiration from greasewood. The calibrated model was used to estimate daily transpiration of groundwater by greasewood growing in an area with a depth to water of about 2 m. The daily rate of groundwater discharge by transpiration during July and August was estimated to be 2.4 mm. A period of 100 days for groundwater discharge at this rate was assumed to estimate an annual discharge of groundwater of 24 cm at the study site.