## 2.11.2. Plant Hydraulic Stress[¶](#plant-hydraulic-stress "Permalink to this headline")
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The Plant Hydraulic Stress (PHS) routine explicitly models water transport through the vegetation according to a simple hydraulic framework following Darcy’s Law for porous media flow equations influenced by [Bonan et al. (2014)](https://escomp.github.io/ctsm-docs/versions/master/html/tech_note/References/CLM50_Tech_Note_References.html#bonanetal2014), [Chuang et al. (2006)](https://escomp.github.io/ctsm-docs/versions/master/html/tech_note/References/CLM50_Tech_Note_References.html#chuangetal2006), [Sperry et al. (1998)](https://escomp.github.io/ctsm-docs/versions/master/html/tech_note/References/CLM50_Tech_Note_References.html#sperryetal1998), [Sperry and Love (2015)](https://escomp.github.io/ctsm-docs/versions/master/html/tech_note/References/CLM50_Tech_Note_References.html#sperryandlove2015), [Williams et al (1996)](https://escomp.github.io/ctsm-docs/versions/master/html/tech_note/References/CLM50_Tech_Note_References.html#williamsetal1996).

PHS solves for the vegetation water potential that matches water supply with transpiration demand. Water supply is modeled according to the circuit analog in [Figure 2.11.1](#figure-plant-hydraulic-circuit). Transpiration demand is modeled relative to maximum transpiration by a transpiration loss function dependent on leaf water potential.

![Image 1: ../../_images/circuit.jpg](https://escomp.github.io/ctsm-docs/versions/master/html/_images/circuit.jpg)

Figure 2.11.1 Circuit diagram of plant hydraulics scheme[¶](#id13 "Permalink to this image")

