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Wu Y, Su H, Cheng L, Qin S, Zou K, Liu Y, Zhou J, Liu P, Zhang L. Exploring hydrological controls on dissolved organic carbon export dynamics in a typical flash flood catchment using a process-based model. Sci Total Environ 2024; 921:171139. [PMID: 38402981 DOI: 10.1016/j.scitotenv.2024.171139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 01/17/2024] [Accepted: 02/19/2024] [Indexed: 02/27/2024]
Abstract
The dynamics of dissolved organic carbon (DOC) export from headwater catchments are of critical importance for the global carbon balance and are driven by complex runoff processes. Most previous studies have used statistical relationships between runoff and DOC concentration to estimate DOC export dynamics. Thus, the coupling mechanisms between runoff generation and DOC export dynamics at the process level were obscured in the fitting parameters and have rarely been addressed. In this study, high-frequency (hourly) discharge and DOC export from a typical flash flood experimental headwater catchment with an area of 1.8 km2 were simulated using a process-based model (INCA-C). The results showed that the INCA-C model successfully captured the hourly dynamics of both discharge and DOC concentrations with a Nash-Sutcliffe efficiency (NSE) of 0.47-0.81 and 0.28-0.70 among moderate events and 0.81-0.85 and 0.19-0.90 among extreme events, respectively. The DOC was exported with distinct concentration dynamics, fluxes, and contributions from the four flow pathways under different storm intensities. At higher intensities, the DOC fluxes were exported by subsurface flows, particularly from shallow organic soil, with greater peaks and shorter time-to-peaks. Exported DOC is primarily sourced from subsurface runoff from the mineral layer (73 %-77 %) during moderate events, whereas it is primarily sourced from subsurface runoff from the organic layer (61 %-79 %) during extreme events. The two contrasting contributions suggest that hydrological pathway controls and DOC dynamic patterns can shift owing to runoff generation influenced by storm intensity. The distinct and variable controls of different flow pathways on DOC export highlight the need to explain the role of hydrology in regulating DOC storm exports through process-based modelling.
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Affiliation(s)
- Yue Wu
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China
| | - Hang Su
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China
| | - Lei Cheng
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China.
| | - Shujing Qin
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China
| | - Kaijie Zou
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China
| | - Yanghe Liu
- China Yangtze Power Co., Ltd., Yichang 443133, China; Hubei Key Laboratory of Intelligent Yangtze and Hydroelectric Science, Yichang 443133, China
| | - Jingzhe Zhou
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Pan Liu
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China
| | - Lu Zhang
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China
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