| 摘要 | 黄土高原水土流失严重, 生态环境脆弱, 水资源短缺, 地下水对保障区域社会经济发展和维持生态
系统平衡具有重要意义, 而该区的地下水转化和补给机制尚不明确。为探究黄土高原水蚀风蚀交错区土壤剖
面深层水分运动及降水对浅层地下水补给的可能性, 利用六道沟小流域分布的粗质地风沙土样地 2013—2016
年土壤剖面 0~600 cm 含水量数据, 运用 HYDRUS-1D 模型对各土层水力参数进行反演和验证, 并用于模拟样
地土壤深剖面 0~1 500 cm 水分运移过程。结果显示, 在平水年 2014 年(439 mm)和干旱年 2015 年(371 mm),
0~600 cm 土壤含水量生长季末与生长季初持平或略有亏缺; 降水充沛年 2013 年(669 mm)和 2016 年(704 mm)
土壤含水量生长季末远高于生长季初, 降水入渗深度超过观测深度(600 cm)。深剖面水分运动模拟显示, 2014
年和 2015 年剖面含水量变化不明显, 水分向深层运移微弱缓慢; 但是, 2013 年和 2016 年降水可分别入渗运移
至 1 100 cm 和 1 200 cm 深度, 远超过样地上生长的旱柳根系区域, 可能补给浅层地下水。在 4 年模拟期间, 平
均土壤蒸发为 14.87 cm·a 1 , 平均植物蒸腾为 33.70 cm·a 1 , 土壤水分主要以植物蒸腾形式损耗。在 2 个丰水年,
得益于较充足的降水和粗质地风沙土壤的高入渗率, 降水大量转化为土壤水快速向下入渗运移, 模拟显示当
年生长季末降水最深运移至 1 200 cm, 至年末已超过模拟深度(1 500 cm), 水分继续运移可能补给浅层地下
水。相关研究结果为黄土高原水蚀风蚀交错区地下水来源和补给机制提供理论依据。 |
| 其他摘要 | The Loess Plateau suffers serious soil and water loss, resulting in a fragile ecological condition with intense water
resources deficit. Groundwater is crucial not only to guarantee regional social and economic development, but also to maintain
ecosystem balance. However, the process of groundwater transformation and recharge on the Loess Plateau is still not entirely
clear. The objective of this study was to investigate water movement in deep soil profile and test the possibilities of precipita-
tion recharge of shallow groundwater in the water-wind erosion crisscross region on the Loess Plateau. Considering the limita-
tions in current equipment and techniques for deep soil profile moisture observation, the HYDRUS-1D model was used to
calculate solute soil hydraulic parameters and simulate deep profile (0–1 500 cm) soil water movement. The datasets used in
the simulation included meteorological data and soil water content in the 0–600 cm soil layer in a willow field plot with ae-
olian sandy soil in the Liudaogou catchment in Shenmu City of Shaanxi Province, China for the period 2013–2016. The upper
boundary condition was set as atmosphere boundary conditions with inputs of rainfall and potential transpiration (T p ) and po-
tential evaporation (E p ) partitioned from crop evapotranspiration (ET 0 ) by using measured leaf area index (LAI) in different
growing periods. The lower boundary condition was set as free drainage. The optimized hydraulic parameters were derived
from a repeated inverse solution process and used to simulate soil water movement in the 0–1 500 cm soil layer. Then the
depth of soil water infiltration and the possibility of shallow groundwater recharge were analyzed. The results showed a slight
soil water content deficit in the 0–600 cm soil layer at both the end and start of growing season in 2014 (439 mm, normal pre-
cipitation year) and 2015 (371 mm, dry year). However, there was surplus soil water content at the end of growing season,
compared with the start of growing season in 2013 and 2016 (both were wet years with 669 mm and 704 mm precipitations),
and rainfall infiltration exceeded observed 600 cm depth. From the simulation results, soil water content of deep soil profile
did not significantly change in 2014 and 2015 with slight and slow water movement into the deeper soil layer, while rainfall
infiltration depth reached 1 100 cm in 2013 and 1 200 cm in 2016. This exceeded rooting zone at the end of 2013 and 2016,
which raised the possibilities of rainfall recharge of shallow groundwater in the study area. For the 4-year simulation period,
average soil evaporation was 14.87 cm·a 1 and average plant transpiration was 33.70 cm·a 1 , soil water contents were mainly
consumed in the form of transpiration. Due to high infiltration rate of the coarse-textured soil in wet years, a large proportion
of rainfall was transformed into shallow groundwater. Dry and wet years alternated on the Loess Plateau with intensive rainfall
variations. Rainfall infiltration in wet years was one important way of shallow groundwater recharge in the region. |
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