Reflectance of AVHRR L1B correlated to MODIS L13A reflectance for a Diachronic vegetation study of Gujarat Environment

摘要

A common understanding of the movement of groundwater recharge by rainwater harvesting thatrnoccurred for the last decades leads to the belief that it had a significant positive impact on the vegetationrnof Gujarat, to the least in areas having crops irrigated by groundwater.rnUsing the historical remote sensing data publicly available from the Internet, assessment of vegetatedrnarea variation between twelve years interval was performed. The total area covered by vegetation wasrnprocessed by districts at 15 days interval for limited significant periods of years 1989 and 2001. The usernof a statistical model in the process of calibration of the band-wise reflectance values for the preparationrnof the NDVI at surface from AVHRR has proven to be very useful. It has also given more practicalrnknowledge on the concept of surface reflectance invariant objects.rnResults show that if such movement had an impact on the total vegetation in some districts, it must havernbeen counter-balanced by the 1999 drought. More study may be required to give some more informationrnabout the accuracy of such assessment. So far, analysis leads to believe that there is a slight reductionrnof vegetation cover in the well vegetated districts over the years of observation.