SATELLITE-DERIVED CROP CALENDAR FOR CANAL OPERATION SCHEDULE IN BHADRA PROJECT COMMAND AREA, INDIA

Spatial information on crop calendars in the command areas of irrigati on systems is useful to irrigation engineers in order to achieve chron ological synchronization between water delivery pattern and crop life cycle. Such synchronization is vital for efficient use of water. The c apability of satellite remote sensing technology to generate spatial c rop calendar information in an irrigated command area and its usefulne ss in the evaluation of water delivery patterns are demonstrated in th is paper. The study pertains to the major crop paddy during the rabi s eason (December to June) of 1992-93, in the Bhadra project command are a of Karnataka state, India. Analyses of multidate Normalized Differen ce Vegetation Index (NDVI) profiles of paddy crop generated from India n Remote Sensing (IRS) satellite data for each distributary command re veal three distinct growth patterns in the study area with each patter n characterized by a particular crop calendar. The spatial variability in crop calendar over the total command area has thus been derived. T he ground truth data obtained in crop cutting experiments (CCEs) valid ate the satellite derived crop calendar. Distributary wise, water deli very data have been studied in conjunction with the satellite derived crop calendar to determine whether the existing pattern of water deliv ery covers the required length of crop life cycle in the command area. It was found that the water supply was stopped about 30 days before h arvesting in some distributaries and in some about 20-30 days before h arvesting. A list of distributaries with greater lags between cessatio n of water supply and crop harvest was provided to irrigation system e ngineers to aid their plans for providing a reliable and predictable i rrigation service. This is possible either through reorganization of c anal operation schedule or through educating farmers about the need fo r adjusting their agricultural activities to match water supply patter ns.