The report presents the seasonal mapping of water bodies along the Andhra coast using satellite data to analyze the pre-monsoon and post-monsoon variations in the reservoirs. Water resources development be it construction of reservoir, anicut or irrigation canal, calls for mapping of the various water bodies to throw light on its behavior in different seasons in order to plan a judicious water management scheme.
Remote sensing methods are considered to be more appropriate than conventional methods for collection of such information owing to their capability to provide broad synoptic and repetitive coverage of the area in a multi-spectral mode.
The coastal area of Andhra Pradesh has been selected to study the pre and post-monsoon surface variations of the water bodies using 1:250000 scale False Color Composite (FCC). In this task, a total of forty FCC’s have been delineated for both the pre and post monsoon seasons. Along the coast forty minor, twenty-four medium and two major reservoirs were identified and mapped. The two major reservoirs, Yeleru and Kanigiri are located in East Godavari and Nellore districts respectively.
The minimum area, which is measurable using the digital planimeter i.e., 0.25 sqkm has been kept as the threshold to map the tanks and lakes.
Kolleru, a freshwater lake that serves as a bird sanctuary covering an area of 853.8 sqkm and Pulicat, a brackish water body measuring 508.1 sqkm are the special features among tanks and lakes. During monsoon season around 904.8 sqkm of the coastal area lying between West Godavari and Krishna districts gets waterlogged.
Due to lack of large scale satellite data, the pre and post monsoon variations in minor reservoirs and small anicuts could not be analyzed. The usage of topographic and remote sensing data in 1:50000 scale would give better results on the minor reservoirs and tanks.
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