Geospatial Application in Desertification Monitoring-Rajasthan, India

Desertification is a significant environmental problem in the arid and semi-arid regions, mainly caused by climate variations, change, and anthropogenic activities. The characteristic of rainfall of Rajasthan is seasonal, erratic, and higher variability is resulting in increasing aridity and degradation of vegetation growth and desertification. This study’s prime objective is to analyze vegetation trends using long-term NDVI from AVHRR for desertification monitoring. Surface vegetation is the most important indicator to assess desertification. In this study, long-term NOAA-AVHRR-GIMMS3G (1983-2011) Normalize Difference Vegetation Index (NDVI) time trends were used as a proxy for Net Primary Production (NPP). To assess the vegetation trend, annual, seasonal, and monthly NDVI, and its mean, maximum, standard deviation, and NDVI Anomaly Index, integral NDVI (iNDVI) were computed. Spatial and temporal variability rainfall and drought were studied using monthly rainfall data from 1983 to 2011 for 102 rain gauge stations. Standardized Precipitation Index (SPI) was computed for all rain gage stations then the SPI results were interpolated. The iNDVI/RF trends were estimated to assess the desertification processes. The 3-month SPI and NDVI anomaly index’s spatial pattern during drought years have a higher negative anomaly during the months from July to September in the greater part of Rajasthan. For example, in 2002, higher SPI values were noticed at Bikaner (August, -3.33, July,-3.13, and September, -2.76) and Chirawa (September,-3.02, August, -2.41). The trends of iNDVI/RF ratio results suggest that about 37 % of the study area was experienced decreasing trends of vegetation growth, ongoing degradation, and desertification process. The districts of Jaisalmer, Jodhpur, Nagaur, Sikar, Bikaner, Churu, and the northwestern part of Barmer are mostly affected by land degradation. About 45% of the study area was experienced the stable condition. Only 9% showed strong positive trends in vegetation growth.