Spatial variation of soil and ground water salinity in a deltaic region of the Indian Sundarbans

Abstract

Deltas are areas where the land and ocean interact in a variety of ways and are an element of the coastal environment. These ecosystems possess unique biological diversity and has been attracting human settlements for centuries. However, deltaic regions are prone to recurring hazards. Soil and water in these regions are always under threat due to cyclonic storms and backwater flow in rivers and creeks. The quality of the soil and water in these regions has a major impact on agricultural output. Kultali block of South 24 parganas district in the state of West Bengal is the part of Sundarbans delta and agricultural activities in the area was difficult due to non-availability of the freshwater and salinity of soil and groundwater during non-monsoon season. Different farm structures were introduced for better management of water for agriculture in this region. A study was undertaken in Kultali block to assess the spatial variations in soil and groundwater salinity after introduction of those farm structures and suggesting the land and water utilization plan for better agricultural production. Observation wells at different locations and depths were installed for monitoring the groundwater in the area. The salinity of the soil and groundwater was monitored for evaluating seasonal change in soil and groundwater quality. The result of the study indicated that pre-monsoon soil and groundwater salinity was more than the post monsoon period. Groundwater salinity was increasing with the depth. Also, the areas near to the river and the creek showed higher salinity level than the rest of the plots in the study area. Soil and groundwater salinity and its spatial and temporal variation maps will be useful for planning agricultural activities in the area.