Based on the disaster report from the Regional Disaster Management Agency (BPBD) of Central Java Province, there have been flood events in the Samin sub-watershed almost every year with the frequency of occurrence of about two to four times a year. The Samin sub-watershed is part of the Bengawan Solo river basin which administratively covers most of which are Karanganyar District and a small portion of Sukoharjo District.
The purpose of this research are (1) to identify of flood vulnerability on Samin Sub-Watershed and the factors that influenced it; (2) to estimate of the loss value on agriculture sector due to flood disaster; (3) to estimate the value of community’s willingness to pay (WTP) in mitigating flood disaster and analyzing the factors that influence it; and (4) obtaining the design of flood mitigation strategies in Samin Sub-Watershed.
This research uses survey method. Flood vulnerability identification is analyzed by using map-overlay approach on geography information system. WTP analysis uses dichotomous choice-contingent valuation method (DC-CVM) technique by using willingness to pay approach on flood mitigation.
The results showed that: (1) There were five of flood vulnerability level, most of Samin sub watersheds area 52.733 Ha (83,05 %) have “prone” to “very prone”. The dominant biophysical aspects causing flood vulnerability in Samin Sub DAS are slope, land use and drainage density; (2) The flood caused the production cost of farming to increase by farmer respondents’total loss are approximately Rp 81,580,000/planting season/Ha or average loss of Rp 1,812,889/person/planting season/Ha (31.21%) per person prior to normal condition; (3) As many as 71% of respondents agreed to participate in the disaster mitigation efforts of the Samin sub watershed area by willingness to pay and the remaining 29% refused. Obtained estimated WTP on Samin sub watersheds is Rp 84,627/individu/year, with range WTP Rp 74,290-94,964/individu/year; and (4) The design of flood mitigation strategies in Samin Sub-watershed through several long-term activities namely Based on the results of the descriptive analysis, it showed that the majority of people in the Samin sub-watershed area chose various forms of flood mitigation including watershed conservation through vegetative engineering, technical civil or a combination of both, such as permanent tree planting in upstream areas, the improvement in agro-forestry, building eco-retention (absorption wells); and socialization to the flood prone community regarding early warning system. For the short-term it could be as well as repairing drainage channel on the midstream and downstream areas, as well as farmers insurance program to accommodate losses suffered by farmers during the flood disaster. Keyword :  flood vulnerability, GIS, willingness to pay, mitigation, Samin Sub-Watershed