NDVI-rainfall correlation and irrigation water requirement of different crops in the sone river-command, Bihar

Abstract

The changing climatic conditions affect the vegetation posing a threat to ecology of the region in general and mankind at large. In this paper, an attempt has been made to understand the relationship between monthly precipitation and the NDVI (Normalised Difference Vegetation Index) data of the Sone river command. For irrigation scheduling and optimal management of water, estimation of irrigation water requirement of the crops is essentially required. Towards this direction, the study has been made to estimate the net irrigation requirement for rice, wheat and maize in the Sone command. The estimation of daily reference evapotranspiration (ET0) by FAO Penman-Monteith method was done for 4 years (2012-2015) using mean meteorological data of Bhojpur and Sasaram in the Sone command. The results show that a good correlation exists between rainfall and NDVI in the kharif season. The mean annual reference evapotranspiration (ET0) was found 3.44 mmday-1 at Bhojpur and 3.58 mmday-1 at Sasaram. The total crop evapotranspiration (ETc) was found to be maximum for rice crop in kharif season and lowest for maize crop in rabi season. Net irrigation water requirement was maximum for winter wheat of 133.66 mm at Sasaram and 112.4 mm at Bhojpur and lowest in summer rice of 35.6 and 61.8 mm at Bhojpur and Sasaram respectively. The high correlation of NDVI with rainfall in Sone command can be used as an alternative to understand the requirement of net irrigation requirement (NIR) during the kharif season.