Soil-moisture and evapotranspiration simulations for irrigated wheat using Soil- Plant-Atmosphere- Water (SPAW ) model

Abstract

goil-Plant -Atmosph erc-Watcr (S PAW) model has been applied 10 sim ula te soil-moisture
profiles for .... hea l in Delhi. Prescr ibed Inrorrnation on wheat growt h characteristics and soils alongwit h daily
meteorological data on evaporation an d rainfall were used to estima te soil- moi sture 31 a locat ion in Delhi for I I
year s. Soil moisture simulations from model runs of consecu tive f,."T"0P seasons from 1979-80 10 1989-90 were in
fa vourable agreement with the gravimetrically measured obse rved dat a. Comparisons were also made for the
mo del gene rat ed eva pot ra nspi rat ion values. Ccrrcla tionv between observed a nd simu la ted soil-moisture in tho:
different layers ra nged from 0 .7 to 0.85 for the tl -year period . Similarl y. integrated co lumn moisture amounts
during d iffe rent stage; of the crop also sho wed sign ificant cor rela tio ns ra nging from 0 .4 to 0 .8 . The model exhibits
a tendency to syste-n nicall v over estimate soil-moist ure du ring the final stage s of crop. possibly due I,)
im perfections in in put . model a rt ifacts an~ observationa l ina deq uaci es. H ONe..-er-. the overall ability of the model
to rep roduce obser ved changes m soil-moisture for activ ely growing wheat crop In Indian con ditions, underlines
ito; uti lity.