search

sumanager56 / SWAP-WOFOST

0 stars 0 forks source link

VG Soil Parameter Calibration #7

Open julieshortridge opened 1 year ago

julieshortridge commented 1 year ago

Task list:

sumanager56 commented 1 year ago

Comparison between observed soil moisture data and latest SWAP simulation results across 3 depths Comparison test

julieshortridge commented 1 year ago

Thanks Suman, these look good. To determine if we should do an offset calibration of the sensor VWC readings, could you please post a table that shows for the corn middle soil sample, at each depth horizon, a) the field capacity based on lab analysis, b) wilting point based on lab analysis, c) field capacity based on visual inspection of sensor readings (corn no irrigation), and d) wilting point based on visual inspection of sensor readings. I imagine the sensor readings for the deep sensor will not exhibit wilting point and possibly not field capacity behavior, if that's the case just put NA's.

Here's a good article overview on VWC sensor calibration - we are basically doing the offset calibration they discuss later in the methods, albeit without the detailed leave-one-out cross validation. https://www.sciencedirect.com/science/article/abs/pii/S0378377417303463

sumanager56 commented 1 year ago

timeseries Corn middle soil sample <html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns="http://www.w3.org/TR/REC-html40">

Horizons | Depth | FC_lab | FC_plot | PWP_lab | PWP_plot | Remarks -- | -- | -- | -- | -- | -- | -- A | 0-15.5" | 13.62 | 25 | 3.64 | 9 | avg of 4,8,12 AB | 15.5-21.5" | 16.87 | 28.5 | 9.45 | 17 | avg of 16 and (20NA) B1 | 21.5-33.5" | 19.34 | NA | 12.16 | NA | avg of 24,28,32 B2 | 33.5-40.5" | 21.93 | NA | 13.1 | NA | avg of 36

sumanager56 commented 1 year ago

Couple of parameters that I found sensitive to Crop Yield and Nitrogen Uptake. I just went through an informal sensitivity analysis to check different Nitrogen Uptake parameters. It seemed like there were some that really changed the results significantly. Some of them are: 1) DVSNLT - development stage above which no crop nitrogen uptake does occur. Changed from an initial 1.3 to 2.0 and the result changed significantly. Found in Nitrogen section in .crp input file. 2) NMAXSO - maximum N concentration in storage organs. Found in Nitrogen section in .crp input file. 3) TCSF_N - Used in equation to calculate NH4-N uptake by plant roots when ammonium concentration in soil moisture is rate limiting. (For the simulation of nitrogen uptake responses to the availability of nitrogen (fertilization field trials), this parameter is calibrated). Changed from 0.5 to 0.8. Found in .snp input file. 4) dz_WSN - effective depth of soil layer. Thickness of the soil layer considered for the simulation of the soil organic matter and nitrogen dynamics. Lager value (e.g. 1.0 m) for Winter wheat and 0.3 for grassland. Changed from 1 to 0.9. Found in .snp input file. 5) vangenuchten alpha value

I just ran a few years for faster simulation. Nitrogen leaching did not change much, but yield and nitrogen uptake increased. Base scenario base_freedrain

Final result PlotResult

sumanager56 commented 1 year ago

Added a 33cm-relatively impervious layer beneath the existing soil layer and ran for entire years 2003 through 2022. Tried different values for van-genuchten parameters and bulk density but the nitrate leaching didn't reduce much. Yield and Nitrogen uptake look better than what we had during our last GCC meeting. Multiyearbest