Agricultural Crop Mapping using Multi Resolution Imagery and Estimation of Crop Water Demands for Efficient Irrigation Water Management

Abstract

Agriculture is an integral part of India, as 70% of it s rural population depend on agriculture for their livelihood. Management of irrigation water resources is needed for sustainable development of agricultural systems. The present study mainly involves evaluating the irrigation need of the crops grown in the Damodar Valley Corporation (DVC) command area, West Bengal,India. First of all the present study carried out mapping of the major crops grown in study area using remotely sensed data. Therefore an extensive ground truth data has been collected as reference data during the two main crop seasons of the region i.e. Rabi and Kharif season. Sentinel-2 imagery with high spatial resolution has been utilized for mapping the croplands. For estimating crop evapotranspiration (ETc), the reference evapotranspiration (ETo) has been evaluated with FAO based Penman-Monteith method. A subsequent analysis for the trend in ETois made with various non-parametric tests and Sen Slope estimator at different time scales. Mann-Kendall and Spearman s rho test along with Modified Mann-Kendall tests were performed. The results from these tests indicated that in most of the periods of a year, the study area is following negative trend in ETo. The significance levels of Z score values are considerably high throughout the year except monsoon and post monsoon periods. Estimation of crop water requirements of the command area has been carried out at the final part of the thesis. Hence, crop coefficients were determined for the dominant crops. Then spatio-temporal evaluation of crop evapotranspiration has been executed using satellite-basedvegetation indices. NDVI, SAVI and LAI derived from Sentinel-2 imagery at different growth stages of the crops were utilized in this consideration. The correlation between crop coefficients with NDVI, SAVI and LAI values established from known crop pixels were used in obtaining the spatial patterns of ET. Requirement of water has been finally computed during the growing periods of the crops.