Identification of River Ecosystem Services through Water Utilization at Merapi Volcano, Indonesia

Abstract Merapi volcano is renowned as one of the world’s most active and densely populated volcanoes. Despite the constant high risk it presents, local residents continue to inhabit the Merapi slopes, primarily due to the ecosystem services that sustain their lives. River ecosystem services in this area are particularly vulnerable to landscape changes, largely driven by volcanic eruptions and human activities. This study aims to define the river ecosystem services by exploring the water utilization in Krasak River, which has been affected by Merapi eruptions from 2010 to 2023. The evaluation of water utilization was conducted using an ecosystem services approach, involving semi-structured interviews with 42 informants in six villages located along the upstream, middle stream, and downstream of the Krasak River. Content analysis was employed to explore water utilization practices and categorize river ecosystem services. The results revealed that water utilization in Krasak watershed comprises the use of springs and wells for supplying drinking needs and domestic needs as well as the use of rivers for irrigation water, fish ponds and recreation activities. Variations in Krasak River water utilization in different segments were influenced by water quality, quantity, accessibility, and the availability of alternative water sources. Based on local perspectives, the prominent river services encompass provisioning (e.g., irrigation, fish ponds, rural water supply, sand and stones), regulating (e.g., water quality maintenance, groundwater quantity), supporting (e.g., primary productivity), and cultural (e.g., recreation, aesthetic value) services. Challenges to river ecosystem services include concerns about river water utilization’s impact on perceptions of the river’s value and the roles of local communities and government in Krasak River management. These findings would contribute valuable insights for enhancing sustainable water resource management in the Merapi area.