Summary of the Irrigation Model in the Community Land Model (CLM):

The Irrigation Model in CLM:
- Allows for irrigation of cropland areas equipped for irrigation.
- Irrigation is applied dynamically based on simulated soil moisture conditions.
- The model is based on the implementation by Ozdogan et al. (2010).

Irrigation Application:
- Croplands are divided into irrigated and rainfed fractions based on a dataset of areas equipped for irrigation.
- Irrigation is only applied to the soil beneath the irrigated crop fraction.
- Irrigation is checked once per day after 6 AM local time.
- Irrigation is required if crop leaf area is greater than 0 and the available soil water is below a specified threshold.

Calculation of Irrigation Amount:
- The soil moisture deficit (D_irrig) is calculated as the difference between the target soil moisture (w_target) and the available soil moisture (w_avail).
- The irrigation moisture threshold (w_thresh) determines when irrigation is initiated, allowing for a deficit before irrigation starts.
- The target soil moisture (w_target) and wilting point soil moisture (w_wilt) are calculated from target and wilting point volumetric soil moisture values.
- Irrigation is applied at a rate equal to the soil moisture deficit divided by the irrigation period (D_irrig/T_irrig).

Water Source and Conservation:
- Irrigation water is taken from river water storage to conserve mass.
- If river water storage is insufficient, the option is to either remove water from the ocean model or reduce the irrigation demand.