Controlling the Brantas river: construction and impact of Japan-supported irrigation infrastructure on the agricultural economy and the environment in East Java

This article examines the crucial role played by Japan in the development of irrigation infrastructure in Indonesia from the 1960s to the 1990s. While the assistance provided by Japan in irrigation infrastructure significantly enhanced the prominence of the Brantas river valleys as a major rice granary during the green revolution, it has been largely overlooked in Indonesian historiography. Despite the historical influence of the Dutch, this article aims to elucidate the reasons behind Japan’s involvement in the modernization of irrigation systems along the Brantas river in East Java, as well as the resultant effects on food production and the environment. Employing a historical approach and drawing on both primary and secondary sources, this study argues that Japan’s role in Indonesia’s irrigation development during the independence period originated from the war compensation fund paid by the Japanese government. This fund subsequently paved the way for greater involvement of Japanese agencies in mutual cooperation in developing irrigation infrastructure. The expansion of irrigated lands and increased rice productivity, facilitated by Japan-supported irrigation infrastructure, mitigated the risks of harvest failure due to droughts and floods. The infrastructure has also played a significant role in flood control during rainy seasons and in securing irrigation water, especially during dry seasons. Additionally, while acknowledging sacrifices incurred during the construction process and the environmental consequences of their operations, it is evident that the Japan-supported irrigation infrastructure effectively tamed the ferocity of the river and optimized its benefits, significantly improving the livelihoods of many people. To ensure the long-term sustainability of Japanese-funded infrastructure along the Brantas River, comprehensive strategies encompassing regular maintenance, technological updates, community engagement, integrated water resource management, agriculture diversification, and climate change adaptation are essential.