Satellite-Based Mapping of Cultivated Area in Gash Delta Spate Irrigation System, Sudan

In this study, a simple methodology for mapping the seasonal cultivated area of the Gash Delta Spate Irrigation System based on satellite images was developed. The methodology combined information from multiple bands to characterize the land surface in terms of spectral indices (e.g., Normalized Difference Vegetation Index (NDVI), and surface temperature (Ts)). Visual interpretations of a conveniently selected image were undertaken to identify and select sample points of interest. The NDVI and Ts values (computed from multi-date images that represented the crop growing period) of the sample points were used to developed typical NDVI and Ts plots. By analyzing these plots and the cropping calendar, an NDVI and Ts threshold-based algorithm was developed to extract the cultivated area of a given season. Analysis of the developed algorithm showed that it was simple, easily modifiable, and had interpretable rules and threshold values. Comparing the extracted cultivated area with the field report area showed a promising application of the methodology to map and estimate the cultivated area from only remote sensing data.