The Impact of Plant Growth Cycle and Root Distribution on the Source Water Partitioning in the Critical Zone
Abstract
Evapotranspiration (ET) is a key component of hydrological cycle that carries central information about plant water use and influences the biogeochemical cycles in the critical zone. The travel time of water particles extracted by ET further describes the mechanism by which water particles with different ages exit through evaporation (E) near the ground surface and through transpiration (T) in the root zone. Despite remarkable advances in quantifying streamflow travel time, the source contribution to and the age sampling mechanism of ET, particularly the T part, are still less understood. This study aimed to explore the impact of plant growth cycle and vertical root distribution on the source water partitioning and the water ages of evaporation (E), transpiration (T), and soil storage. To this end, we used and advanced the recently developed Lagrangian particle-tracking model, EcoSLIM, to distinguish E and T particles using a mass balance approach. This framework also allowed for determining the fraction of particles with different sources (i.e., rainfall, snowmelt, and pre-stored groundwater) captured by T at different root zone layers. We observed that the modified particle-tracking model yielded accurate results in closing the water balance as evidenced by R2 > 0.9 for E, T, and Q. The results from three scenarios with different plant growth period and root fraction distribution demonstrated that the rooting depth together with the synchronicity between the climatic forcing and the timing of plant growing cycle control the access of plants to young and old water ages in contrasting ways. Plants showed preference to young ages in all cases unless the deep rooting network allows for the extraction of old ages during the dry periods.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H11A..05B