జర్నల్ ఆఫ్ రిమోట్ సెన్సింగ్ & GIS

నైరూప్య

Investigate the Sensitivity of the Satellite-Based Agricultural Drought Indices to Monitor the Drought Condition of Paddy and Introduction to Enhanced Multi-Temporal Drought Indices

Jayawardhana WGNN, Chathurange VMI

Vegetation Health Monitoring from space and the Normalized Difference Vegetation Index (NDVI) are widely used in the field of photosynthesis capacity of vegetation. The number of drought indices calculates by comparing the NDVI of time of observation with the Long term NDVI values and called as “multi-temporal drought indices” in this study. Some are developed using only the data of the time of observation and no time-series data required, therefore called “ non-temporal drought indices ” . This study analyzed multi-temporal and non-temporal drought indices calculated using NDVI, Normalized Difference Water Index (NDWI), and Land Surface Temperature (LST). These indices utilize not only to monitor agricultural droughts but monitor the crop condition also. Freely available 19 years MODIS satellite data (MOD13Q1 and MOD11A2) were used to calculate them and discussed the sensitivity of the indices for the monitoring of agricultural droughts and crop conditions in the rain-fed dry zone paddy agriculture in Sri Lanka. For that, the Relationship of all variables with Climate Hazards Group Infrared Precipitation with Station data (chirps), rainfall anomaly, and Standardized Precipitation Index (SPI) were analyzed. This study observed that the NDWI Anomaly and Vegetation water condition Index (VWCI) shows a considerable relationship with SPI and rainfall. Also, this study identified that the false drought conditions can be seen in multi-temporal drought indices, due to the changes of the time of the start of the season and suggested a method to overcome such errors in heavily dynamic climatic areas. The new approach is called “Enhanced multi-temporal drought indices”.