Abstract
This study assesses the sustainability of the Kamphaengsaen (KPP) and Phophraya (PPP) projects located in the Tha Chin Basin, Thailand. The assessment is based on the investigation of sustainability indicators using principal component analysis. The dominant indicators affecting sustainability are identified. The key indicators are weighted and computed to obtain the irrigation sustainability index (ISI) used to classify the sustainability into five levels. The results for KPP show net farm income, awareness on irrigation water use, matching of water delivery schedule and agricultural operation, and field application ratio being the major sustainability indicators. For KPP, six zones show a very low sustainability level; five zones are low; 11 zones are medium; four zones are high and one zone very high. Four key indicators are found in PPP, including perception of drained water quality, satisfaction on adequacy of water distribution, field application ratio, and net farm income. For PPP, one zone shows a very low sustainability level; three zones are low; five zones are medium; one zone is high and one very high. The ISI developed may also help stakeholders and policy makers to understand the roles, influences and implications of the key indicators towards sustainable management of the irrigation sector in the country. Copyright © 2010 John Wiley & Sons, Ltd.