2023/09/01 by Paolo Nasta, Jirka Šimůnek, Jiřı́ Šimůnek +3
Engineering · Environmental Science · #Hydrology and Watershed Management Studies #Plant Water Relations and Carbon Dynamics #Soil and Unsaturated Flow
paper · pdf · doi:10.1002/hyp.14982
openalex publication_date 2023/09/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
Abstract The temporal origin of drainage, evaporation, and root water uptake (RWU) are indicators of ecosystem functioning that shed light on how natural and anthropogenic disturbances affect plant resilience and aquifer vulnerability. A virtual tracer experiment was carried out in HYDRUS‐1D using data from a soil lysimeter planted with winter rye in Austria. The RWU ( τ R ), evaporation ( τ E ), and drainage ( τ D ) transit times ( τ ) were determined by using the actual dispersivity optimized in a prior study. First, τ R and τ D were compared to RWU ( τ PT,R ) and drainage ( τ PT,D ) advective transit times estimated using the particle tracking algorithm. The τ R values were in agreement with τ PT,R while large discrepancies were detected when estimating drainage transit times using the two approaches. A sensitivity analysis revealed that dispersivity had a mild, poor, and strong influence on τ R , τ E , and τ D . The longitudinal dispersivity describes how a tracer spreads along the flow paths. The longer the flow paths, the more dispersion affects the tracer transport. On average, water parcels originating from rainfall in the growing season took 18 and 201 days to reach the roots (with RWU being 21% of rainwater) and the soil profile bottom (with drainage being 36% of rainwater), respectively. In contrast, 10% of rainwater that fell in the dormant season became RWU after 264 days, while 79% became drainage after 294 days. The temporal origin of water can be explored in other plots by using the guidelines proposed in this study.