Evaluating potential groundwater recharge in the unsteady state for deep-rooted afforestation in deep loess deposits
Evaluating potential groundwater recharge in the unsteady state for deep-rooted afforestation in deep loess deposits
复制标题
黄土深层深根造林非稳态地下水补给潜力评估
DOI：
10.1016/j.scitotenv.2022.159837
复制
发表时间：
2022
影响因子：
9.8
通讯作者：
Siddique Kadambot H.M.
中科院分区：
文献类型：
--
作者：
Chen Guangjie;Meng Tingfang;Wu Wenjie;Si Bingcheng;Li Min;Liu Boyang;Wu Shufang;Feng Hao;Siddique Kadambot H.M.
从浅根造林到深根造林，由于蒸腾作用大，地下水补给量减少。然而，在补给过程中达到稳定状态是具有挑战性的，并且没有方法可用于评估非稳定状态下的潜在地下水补给。因此，本研究提出了一种新的非稳态地下水补给量的定量方法：（1）用氯离子累积年龄法计算深根造林最大根深（D2）处的水龄（A2），（2）用多年平均孔隙水流速乘以A2确定浅根植被下A2所对应的土壤深度（D1）;（3）地下水补给量的减少量（WAR）计算方法为：深度差乘以D_1 ~ D_2的平均含水量，再除以林龄。深根造林的地下水平均补给量等于浅根植被下地下水年平均补给量减去地下水平均补给量。在4种土地利用方式下，对25 m以上的土壤剖面进行了土柱分析。（H. rhamnoides）、侧柏Platycladus orientalis（L.）Franco（P. orientalis）、刺槐Robinia pseudoacaciaL.（R.刺槐）和草地，测定土壤含水量、根系分布、氯离子和氚含量。结果表明：（1）H下最大根深分别为11.0 ± 0.5、20.2 ± 1.2和22.6 ± 0.8 m，土壤水分亏缺分别为373.48、823.65和1847.92 mm。rhamnoides、P. orientalis和R.刺槐;（2）土地利用变化后地下水补给量尚未达到稳定状态;（3）草地地下水平均年补给量为89.12 mm yr− 1，占年平均降水量的16%;深根造林没有显著差异，分别为83.55、84.91和85.65 mm yr− 1。rhamnoides、P. orientalis和R. pseudoacacia，分别。该研究为合理评价土地利用变化过程中地下水资源的动态变化提供了理论依据。
Groundwater recharge reduces due to high transpiration from shallow-rooted to deep-rooted afforestation. However, reaching a steady state in recharge process is challenging and no methods are available for assessing potential groundwater recharge under unsteady state. Hence, this study developed a new method to quantify groundwater recharge in the unsteady state by (1) calculating the water age (A2) at maximum root depth (D2) for deep-rooted afforestation using the chloride accumulative age method; (2) determining the soil depth (D1) corresponding toA2under shallow-rooted vegetation using the multi-year average pore water velocity multiplied byA2; (3) calculating the reduction in groundwater recharge (∆R) from shallow- to deep-rooted afforestation as the depth difference multiplied by the average water content betweenD1andD2, divided by stand age. The average groundwater recharge for deep-rooted afforestation is equal to the average annual groundwater recharge under shallow-rooted vegetation minus ∆R. Soil cores with >25 m soil profiles below four land-use types ofHippophae rhamnoidesLinn.(H. rhamnoides),Platycladus orientalis(L.)Franco(P. orientalis),Robinia pseudoacaciaL.(R. pseudoacacia), and grassland were collected to measure soil water content, root distribution, and chloride and tritium contents. The results revealed that: (1) maximum root depths were 11.0 ± 0.5, 20.2 ± 1.2, and 22.6 ± 0.8 m, with soil water deficits of 373.48, 823.65, and 1847.92 mm underH. rhamnoides,P. orientalis, andR. pseudoacacia, respectively; (2) groundwater recharge following land-use change has not reached a steady state; (3) an average annual groundwater recharge was 89.12 mm yr−1under grassland, amounting to 16 % of the average annual precipitation; deep-rooted afforestation did not significantly differ, with 83.55, 84.91, and 85.65 mm yr−1underH. rhamnoides,P. orientalis, andR. pseudoacacia, respectively. This study contributes to a rational assessment of groundwater resources under unsteady state during land-use change.