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back to ["River width computation"] [[BR]]

__Other model__ :[[BR]]
- Elvira model : model 4 with river >2nd order[[BR]]
Log10(Wet width + 1) = 0.22734+ 0.20045 (log10 catchment area) + 0.25939 (log 10 Shreve index)[[BR]]

- Thornton model : W = 4.98 CA0.47 [[BR]]

__Models tested__:[[BR]]
'''Linear regression'''
 * Model 1 : width ~ a*catchment_area + b
 * Model 2 : log(width) ~ a*log(up_area)+ b
 * Model 3 : log(width) ~ a*log(up_area) + uga + b 
 * Model 4 : log(width) ~ a*log(up_area) + b*log(shreve index) + c
 * Model 5 : log(width) ~ a*log(up_area) + b*log(shreve index) + uga + c

'''Non linear regression''' with library(nlme)
 * Model 1: width~alpha*up_area^beta
 * Model 2 : width~gamma*shreve^lambda  (à tester : width~gamma*strahler^lambda

   
 *  Data extraction :
   * year > 1987  (RHP)
   * Period : april-october
   * complete sampling method
   * shreve >1


__Model Validation for linear regression__
 * Residuals versus fitted values to verify homogeneity
 * QQ-plot or histogrqam of the residuals for normality
 * Residuals versus each explanatory variable to check independence

__Up cathcment area ~stream order__
||[[Image(source:data/Docs/trac/RiverWidth/up_area_shreve.jpeg,300px)]] ||[[Image(source:data/Docs/trac/RiverWidth/up_area_strahler.jpeg,300px)]]
||Up catchment area ~ shreve|| Up catchment area ~ strahler||

__Width ~stream order__
||[[Image(source:data/Docs/trac/RiverWidth/width_shreve.jpeg,300px)]] ||[[Image(source:data/Docs/trac/RiverWidth/width_strahler.jpeg,300px)]]
||River width ~ shreve|| River width ~ strahler||