Salinity risk to agricultural landuse due to sea level rise: a case study in Dhaula Union of Barguna Sadar Upazilla

Abstract

Gradual increase of areal extent of saline water with sea level rise in coastal region may cause a serious alarming situation for agriculture. Salinity affects crops depending on degree of salinity at the critical stages of growth, which reduces yield and in severe cases the total yield is lost. In this study, historic high tidal water level data in the study area shows a rising trend which indicates the increase of areal extent of tidal inundation in future. In addition, concentration of salinity shows an increasing trend over the years in the area. So there is a possibility of having consequence of increasing saline water concentration as well as areal extent of saline water with different levels in future. In this connection, the present study shows, the agricultural land use risk from salinity perspective due to sea level rise from 2015 to 2030 in Dhalua Union under Barguna Sadar Upazila. The study findings also show that, all water level stations are observing a rising trend which also influences on high tidal inundation extents in different years. Inundation extent will become more than doubled estimated to 9.64 sq. km to 20.58 sq.km from the year 2015 to 2030. In 2015, about 38% of total agricultural land will be inundated by peak high tidal inundation which will be also more than doubled in 2030. There is an inverse relationship exist between high tidal water level and salinity (Ec) level. Peak high tidal inundation with sea level rise induced salinity concentration will be decreased in future. The Dhalua union occupies a total 25.16 sq. km of agricultural land of which, in 2015, 17.52 %, 12.67 %, and 8.50 % agricultural land will be under moderate, high and very high risk categories respectively. In 2020, about 0.299 sq.km of agricultural land will be under low risk of salinity (441 – 680) which is absent for 2015 and on the other hand, no agricultural land will be found under very risk of salinity. Moderate risk of salinity area will be significantly increased amounted to 47.45 % of total agricultural land in 2020. In 2025, 75.31 % of total agricultural land will be under low risk of salinity. Almost 95 % of the inundated crop area will be exposed by very low risk of salinity and remaining will be under low risk of salinity in 2030.