Input data

[sim.moulds]

N.B. The question below was in an email to Peter Burek; at his suggestion I'm posting it here in case it's useful to anyone else. Perhaps we could use this thread to discuss the origin - and potential for improvement - of other input variables.

I'm using the Community Water Model for some work I'm doing in the Ganga basin in northern India. First, thank you for making the model available to the community - it's a great tool and learning resource, and (in my opinion) a good example of using Python and OOP principles for hydrological modelling.

I'm attempting to understand how each variable included in the 30' input dataset was derived. The map of the Crop Group Number appears to be an average value since it contains floating point values not integers, whereas my understanding of the CGN concept was that it should be an integer between 1-5. Please could you briefly describe how the input map was computed?

Thanks a lot for your time.

Simon

[PeBu]

You are right the Crop Group number is a int between 1-5

Crop group number is used to calculate the fraction of soil moisture between soil moisture at field capacity (pF2, 100 cm) [mm water slice] and soil moisture at wilting point (pF4.2, 10^4.2 cm) that can be extracted from the soil without reducing the transpiration rate. The value of p is a function of vegetation type and potential evapotranspiration. The crop group number is proportional to p. E.g. Olive groves are adapted to dry climate, therefore they can extract more water from drying out soil than e.g. rice. The crop group number of olive groves is 4 and of rice fields is 1.

 

For the 30' we used a 6'  map and aggregated it to 30' . Therefore the floating numbers.

Best,

Peter