Remote sensing based agricultural drought assessment in Palar basin of Tamil Nadu state,India |
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Authors: | T Murali Krishna G Ravikumar M Krishnaveni |
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Institution: | 1.Centre for Water Resources,CEG, Anna University,Chennai,India;2.Department of Chemical Engg, A C Tech,Anna University,Chennai,India |
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Abstract: | Agricultural drought has been a recurrent phenomenon in many parts of India. Remote sensing plays a vital role in real time
monitoring of the agricultural drought conditions over large area, there by effectively supplementing the ground mechanism.
Conventional drought monitoring is based on subjective data. The satellite based monitoring such as National Agricultural
Drought Assessment and Monitoring System (NADAMS) is based on the crop condition, which is an integrated effect of soil, effective
rainfall, weather, etc. Drought causes changes in the external appearance of vegetation, which can clearly be identified (by
their changed spectral response) and judged using satellite sensors through the use of vegetation indices. These indices are
functions of rate of growth of the plants and are sensitive to the changes of moisture stress in vegetation. The satellite
based drought assessment methodology was developed based on relationship obtained between previous year’s Normalised Difference
Vegetation Index (NDVI) profiles with corresponding agricultural performance available at district/block level. Palar basin,
one of the major river basins in Tamil Nadu state was selected as the study area. The basin covers 3 districts, which contain
44 blocks. Wide Image Field Sensor (WiFS) of 188m spatial resolution from Indian Remote Sensing Satellite (IRS) data was used
for the analysis. Satellite based vegetation index NDVI, was generated for Samba and Navarai seasons in the years 1998 and
1999. An attempt has been made to estimate the area under paddy. It was also observed that, there was reduction in the crop
area as well as vigour in the vegetation in both Samba and Navarai seasons in 1999 when compared with 1998. Drought severity
maps were prepared in GIS environment giving blockwise agricultural water deficiency status. |
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