Book of Extended summaries ISDA

International Conference on Reimagining Rainfed Agro-ecosystems: Challenges &
Opportunities during 22-24, December 2022 at ICAR-CRIDA, Hyderabad
Methodology
VegDRI model was produced by the National Drought Mitigation Centre (NDMC) in
collaboration with USGS and Centre for Earth Resources Observation and Science (EROS)
and the High Plains Regional Climate Center (HPRCC). According to methodology proposed
by Wardlow et al., the VegDRI Model consists of three primary steps. The first step was to
process, summarize, and organize the data for the eight variables used in VegDRI model into
a database. A 16-year (2000 – 2015) historical record of climate-based drought index and
satellite-derived vegetation indices (VI) observations and information from four temporally
static biophysical variables were included in the training database. For present study area, each
variable information was summarized for 70 weather stations and sequentially ordered in the
database for model development. The second step was to generate an empirically derived
model by applying a supervised classification and regression-tree (CART) analysis technique
to information in the database. The third step was to apply the models to the geospatial data to
produce a 500 m resolution VegDRI map for the study area. The VegDRI map contains seven
categories of varying levels of drought-induced vegetation stress, based on the PDSI drought
classification (Palmer, 1965). In modified VegDRI model, instead of using biweekly AVHRR
NDVI as mentioned in the original methodology MODIS NDVI data generated from daily
surface reflectance data (MOD09A1) was used under satellite variables. Similar approach was
used by Yonatan (2013) and Won-Ho Nam (2017). One of the biophysical variable landuse
landcover (LULC) was confined to kharif crops and irrigated areas were also masked.
Results
VegDRI, the depiction of vegetation stress across the study area indicated that the growth of
long duration crops like redgram during kharif was near-to-normal during the study period
except the years 2001, 2004 and 2015. During the years 2001 and 2015, the crop exhibited
near-to-normal conditions in 60 and 65 percent locations, respectively. However, pre-drought
stress also occurred in 35 percent locations during these years and mediocre drought was
observed in 5 percent locations during 2001. Whereas the year 2004, was predominantly predrought
stress in 65 percent locations and near-to-normal in 35 percent locations. Thus,
VegDRI index indicated mostly near-to-normal condition of redgram in the study area during
the study period. VegDRI index for short duration crops like greengram was near-to-normal
during the study period in more than 50 percent of the locations except during 2008, 2010 and
2013. During these years (2008, 2010, 2013), unusually moist situation existed in more than
50 percent locations. The year 2015 exhibited near-to-normal and unusually moist situations in
equivalent areas.
Irrespective of soil type or depth the VegDRI index was near-to-normal in case of redgram and
near-to-normal to unusually moist in case of greengram in the entire study area during the study
period. In redgram, pre-drought condition was observed only during 2001 and 2004 in deep
Emerging approaches (RS, AI, ML, Drones etc) for crop management &assessment
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