Brackish water aquaculture development and its impacts on agriculture land: A case study on coastal blocks of Purba Medinipur district, West Bengal, India using multi-temporal Satellite data and GIS Techniques

摘要

Shrimp farming is playing a great role in present Indian economy. It has a big contribution to the economy of a developing country like India but is always subjected to some adverse environmental consequences. Following the same route, this study has been made on the growth pattern of commercial aquaculture activity and its effect on traditional agriculture on five coastal blocks of Purba Medinipur district, West Bengal, India. The analysis of series of multi-temporal satellite data provided the accurate quantification of the present status of land use and also help to understand the land cover changes due to the shrimp farming during 2008 to 2016 using GIS technique. The rapid growth (increase) of brackish water tanks/ponds has its highest effect on the agriculture land among all other land cover classes. This growth has both direct and indirect effect on agricultural land classes. Precisely, it has decreased the area of the agriculture land and on the other hand, due to leakage, seepage, and overflow of saline water to nearest agriculture land, it affects badly in the productivity. In all these five blocks, from the year 2008 to 2016, 1945.32 ha agriculture land has been decreased, in which 1546.54 has decreased due to brackish water tanks/ponds as a result of shrimp farming. The conversion rate is much higher in the year 2012-2016 (1126.74ha) compared to 2008 to 2012 (416.09 ha). Other two effective classes are settlement and freshwater tanks ponds which have converted the agriculture land by 265.65 ha and 131.77 ha respectively from 2008-2016. By analyzing soil salinity, it has been noticed that soil pH and soil salinity has drastically increased in the agricultural land situated up to 10m from shrimp farm. A noticeable change is seen in soil salinity and soil pH between the years 2012-2016. As a consequences of above mentioning reasons, 1185 ha agricultural land is badly affected in the study area.