Water retention data: Rainfed conditions

Exercise objective:

·    Use of measured water retention characteristics; rainfed conditions.

Suggested reading:

Chapter 7.4 of the book, ORYZA2000: modelling lowland rice.

Exercise: 

Ex-V.8. In the soil data file PADDY.DAT, retain the fixed percolation rate (FIXPERC) at 30 mm d-1. Create a rerun file in which we use observed data for the water retention characteristics:

SWITPF = 0 ! Data

Run ORYZA2000. Study the error message and fix the problem. A. Since we now use observed data, we have to supply values for WCFC, WCWP and WCAD: remove the asterisk (*) to activate the data supplied in the data file. Run ORYZA2000 again and examine the output. Note that the differences between the default and the (single) rerun are small. The Van Genuchten parameters apparently describe the observed water retention characteristics sufficiently accurately.