Impact Of Seawater Intrusion Bund On Soil & Water Conservation Along The Coastal Line Of Poonakary, Sri Lanka

Abstract

Abstract Saltwater intrusion into coastal aquifers is reported at coastal region of Poonakary, Kilinochchi district. A sea water intrusion bund was constructed by United Nations Development Programme in 2015 to reduce the issues with seawater intrusion. This study aimed to measure the variations of soil salinity and pH before (2015), just after (2016) and three years after (2018) the construction of bund and to identify the impacts of seawater intrusion bund on soil, water quality and crop improvement in the area. The study was conducted in three selected Grama Niladari Divisions of Poonakary, during July to September period in 2018. Soil samples were collected from 30 locations at different sampling depths and the locations were recorded by using GPS and fifteen water samples were collected to measure the water quality parameters and the values compared with WHO standards. A questionnaire survey was conducted to assess the crop improvement in the selected locations. When comparing the soil pH in 2016 and 2018, at all depths except 60cm, changes were highly significant and at 60 cm, it was significant. The Soil EC during 2016 and 2018 revealed that, at 15cm, 30cm and 60cm the changes were significantly different and at 45cm it was not significantly differ due to hardpan formation. A considerable improvement in the water quality and yield improvement of paddy were observed. The study reveals that, the seawater intrusion bund can be considered as a potential permanent solution for seawater intrusion at Poonakary.