VULNERABILITY AND ADAPTATION ASSESSMENT OF THE SHRIMP FARMINGTO EXTREME FLOODS EVENTS : A CASE STUDY OF THE BANGPAKONGSUB-BASIN, BANGPAKONG RIVER BASIN IN CHACHOENGSAO PROVINCE

Abstract

Flood disasters associated with tropical storms have caused extensive and repeated damage to shrimp farms located in the Bangpakong River Basin, Chachoengsao Province, Thailand, which features the largest area of inland shrimp farming in the country. Chachoengsao province is a prime shrimp producing area for domestic consumption and exports, but the province is always threatened by floods. This thesis aims to assess the vulnerability of shrimp farms to flooding and recommend the adaptation options for coping with floods based on past flood events. Key factors affecting the adaptive capacity of shrimp farmers in Thailand and cost-benefit of each adaptation option are also aims of the research. A flood vulnerability map was developed based on the geo-environmental characteristics of the study area. The map was produced through the use of geographic information system (GIS) methods and a multicriteria evaluation. The current and future vulnerability map indicates that the majority of shrimp farms in the Bangpakong River Basin are highly vulnerable to flooding when the 10-day cumulative rainfall is greater than 250-300 mm. The highly vulnerable area identified by the map is consistent with the area impacted by flooding in 2011. Key factors affecting the adaptive capacity of shrimp farmers were carried out using questionnaires and person-to-person interviews. Approximately 100 shrimp farmers who had experienced previous flood events were interviewed to help classify the impact scales of key factors on adaptation. Five socio-economic characteristics (education level, farming experience, income level, farm size, and supplemental occupations) are important factors in making the decision to apply adaptive alternatives. Latter, this research developed a flood risk map by combining the probability of flood events and vulnerability map based on physical characteristic of the area and socioeconomic conditions of shrimp farmers. Analysis of recommended risk reduction measures was performed by comparing the net benefits and costs of different strategies. Damage costs from flooding to shrimp farming were also estimated for the base case (no change in actions). The flood risk map shows that two-third of shrimp farms are highly vulnerable to flooding when 10-day accumulated rainfall is greater than 250 mm. Increasing dike height could yield higher net benefits from selling raw shrimp more than other flood adaptation measures, but it would be appropriate for flood risk areas where are likely to be flooded in every two years. Non-structural flood control is an alternative measure for shrimp farmers who lack financial means and accesses such as early harvesting and shift crop calendar. With increasing climate change threats, these research results are useful for planning and creating policies that can reduce flood damage to shrimp farms in vulnerable zones. The results can also be applied to other areas facing similar conditions.