Evaluating potential groundwater recharge in the unsteady state for deep-rooted afforestation in deep loess deposits

Guangjie Chen; Tingfang Meng; Wenjie Wu; Bingcheng Si; Min Li; Boyang Liu; Shufang Wu; Hao Feng; Kadambot H M Siddique

doi:10.1016/j.scitotenv.2022.159837

Evaluating potential groundwater recharge in the unsteady state for deep-rooted afforestation in deep loess deposits

Sci Total Environ. 2023 Feb 1;858(Pt 2):159837. doi: 10.1016/j.scitotenv.2022.159837. Epub 2022 Oct 29.

Authors

Guangjie Chen¹, Tingfang Meng², Wenjie Wu³, Bingcheng Si⁴, Min Li³, Boyang Liu³, Shufang Wu³, Hao Feng⁵, Kadambot H M Siddique⁶

Affiliations

¹ Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, 712100 Yangling, Shaanxi Province, China; College of Water Resources and Architectural Engineering, Northwest A&F University, 712100 Yangling, Shaanxi Province, China; State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, 712100 Yangling, Shaanxi Province, China.
² State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, 712100 Yangling, Shaanxi Province, China; State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, 712100 Yangling, Shaanxi Province, China.
³ Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, 712100 Yangling, Shaanxi Province, China; College of Water Resources and Architectural Engineering, Northwest A&F University, 712100 Yangling, Shaanxi Province, China.
⁴ Department of Soil Science, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
⁵ Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, 712100 Yangling, Shaanxi Province, China; State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, 712100 Yangling, Shaanxi Province, China; State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, 712100 Yangling, Shaanxi Province, China. Electronic address: nercwsi@vip.sina.com.
⁶ The UWA Institute of Agriculture and School of Agriculture and Environment, The University of Western Australia, LB 5005, Perth, WA 6001, Australia.

PMID: 36411672
DOI: 10.1016/j.scitotenv.2022.159837

Abstract

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 to A₂ under shallow-rooted vegetation using the multi-year average pore water velocity multiplied by A₂; (3) calculating the reduction in groundwater recharge (∆R) from shallow- to deep-rooted afforestation as the depth difference multiplied by the average water content between D₁ and D₂, 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 of Hippophae rhamnoides Linn. (H. rhamnoides), Platycladus orientalis (L.) Franco (P. orientalis), Robinia pseudoacacia L. (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 under H. rhamnoides, P. orientalis, and R. 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^-1 under 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^-1 under H. rhamnoides, P. orientalis, and R. pseudoacacia, respectively. This study contributes to a rational assessment of groundwater resources under unsteady state during land-use change.

Keywords: An unsteady state; Groundwater recharge; Land-use change; Water age.

MeSH terms

Chlorides*
Groundwater*
Soil
Tritium
Water

Substances

Chlorides
Soil
Tritium
Water