# Actual Water Uptake

Once the potential water uptake has been modified for soil water conditions, the actual amount of water uptake from the soil layer is calculated:

         $$w\_{actualup,ly}=min\lfloor w''*{up,ly},(SW*{ly}-WP\_{ly})\rfloor$$                                          5:2.2.7

where $$w\_{actualup,ly}$$ is the actual water uptake for layer $$ly$$ (mm H$$*2$$O), $$SW*{ly}$$ is the amount of water in the soil layer on a given day (mm H$$*2$$O), and $$WP*{ly}$$ is the water content of layer $$ly$$ at wilting point (mm H$$\_2$$O). The total water uptake for the day is calculated:

        $$w\_{actualup}=\sum^n\_{ly=1} w\_{actualup,ly}$$                                                                   5:2.2.8

where $$w\_{actualup}$$ is the total plant water uptake for the day (mm H$$*2$$O), $$w*{actualup,ly}$$ is the actual water uptake for layer $$ly$$ (mm H$$\_2$$O), and n is the number of layers in the soil profile. The total plant water uptake for the day calculated with equation 5:2.2.8 is also the actual amount of transpiration that occurs on the day.

           $$E\_{t,act}=w\_{actualup}$$                                                                                     5:2.2.9

where $$E\_{t,act}$$ is the actual amount of transpiration on a given day (mm H$$*2$$O) and $$w*{actualup}$$ is the total plant water uptake for the day (mm H$$\_2$$O).

Table 5:2-2: SWAT+ input variables that pertain to plant water uptake.

| Variable Name | Definition                                 | Input File |
| ------------- | ------------------------------------------ | ---------- |
| EPCO          | $$epco$$: Plant uptake compensation factor | .bsn, .hru |


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