Exploring a Balinese irrigation water management system using agent-based modeling and game theory

In the irrigation sector, water-related conflict has been compounded due to social issues such as climate change and urbanization-induced population dynamics. Although Irrigation Management Transfer (IMT) and Participatory Irrigation Management (PIM) were implemented for sustainable irrigation infrastructure management, results of PIM/IMT implementations exhibit conflicts between WUAs and the lack of water users' associations' (WUAs) participation in management. To unfold PIM/IMT issues, Agent-Based Model (ABM) helps analyze conflicts, and game theory helps analyze governing concepts underlying cooperative management such as rules. This study discusses the applicability of ABM and game theory to analyze conflicts over surface irrigation water and harvesting labor and also aims to present solutions to increasing conflicts due to labor resource depletion owning to urbanization. To investigate cooperative WUAs amid the pressure of social changes, we chose WUAs in Bali, Indonesia, known as "subaks". Rice cultivation management practices of five subaks in the study area were identified by stakeholder analysis approach, and we developed an ABM to model water management of six agents representing subaks. To examine influence of harvesting labor supply on water management, noncooperative game theory was applied, and three harvesting labor scenarios and two strategies were generated. Scenario analysis indicates that with severe shortages in the harvesting labor supply, harvesting labor allocation orders could compound the decline in annual rice production. This study also establishes that although current management practices maintain cooperative relationships between subaks and flexible management practices likely strengthen cooperative relationships, social changes could accelerate farmers' noncooperative behavior. To resolve conflicts, subaks need to develop cooperative relationships on a larger scale, but social issues go beyond the intra-community level and will require government intervention to efficiently use deceasing resource supply. This method using ABM and game theory will contribute to the development of socio-hydrological analysis approach to sustainable resource allocation in PIM/IMT study.