Implementing Dynamic Root Optimization in Noah-MP for Simulating Phreatophytic Root Water Uptake

Ping Wang, Guo Yue Niu, Yuan Hao Fang, Run Jian Wu, Jing Jie Yu, Guo Fu Yuan, Sergey P. Pozdniakov, Russell L. Scott

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Widely distributed in arid and semiarid regions, phreatophytic roots extend into the saturated zone and extract water directly from groundwater. In this paper, we implemented a vegetation optimality model of root dynamics (VOM-ROOT) in the Noah land surface model with multiparameterization options (Noah-MP LSM) to model the extraction of groundwater through phreatophytic roots at a riparian site with a hyperarid climate (with precipitation of 35 mm/yr) in northwestern China. VOM-ROOT numerically describes the natural optimization of the root profile in response to changes in subsurface water conditions. The coupled Noah-MP/VOM-ROOT model substantially improves the simulation of surface energy and water fluxes, particularly during the growing season, compared to the prescribed static root profile in the default Noah-MP. In the coupled model, more roots are required to grow into the saturated zone to meet transpiration demand when the groundwater level declines over the growing season. The modeling results indicate that at the study site, the modeled annual transpiration is 472 mm, accounting for 92.3% of the total evapotranspiration. Direct root water uptake from the capillary fringe and groundwater, which is supplied by lateral groundwater flow, accounts for approximately 84% of the total transpiration. This study demonstrates the importance of implementing a dynamic root scheme in a land surface model for adequately simulating phreatophytic root water uptake and the associated latent heat flux.

Original languageEnglish (US)
Pages (from-to)1560-1575
Number of pages16
JournalWater Resources Research
Issue number3
StatePublished - Mar 2018


  • hyperarid regions
  • land surface models
  • phreatophytes
  • plant optimality
  • root water uptake

ASJC Scopus subject areas

  • Water Science and Technology


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