Our study

General study theme

Smart River Management from the Mountain to the Sea: Connecting the World

Food security, water supply, river environments, and community resilience along river basins are threatened by both human and natural drivers. The connectivity of water and sediments along a river basin - in Japan, Vietnam, the Philippines, Africa, and other parts of the world- is being altered by human interventions such as dam construction, irrigation expansion, deforestation, sand mining, and land-use change. In areas such as the Vietnamese Mekong Delta (VMD), for example, subsidence and shrinkage add additional layers of vulnerability.

At the Kantoush Laboratory (Disaster Prevention Research Institute, Kyoto University) we focus on achieving resilience of hydraulic infrastructures, water systems, river ecosystems, agricultural production, and local communities under changing climate and multi-hazard conditions. We drive this by means of smart monitoring, smart mitigation measures and strategies, the development of upgraded dams and reservoir systems, and the restoration or preservation of natural sediment dynamics to improve river ecosystem conditions. Our core interest spans flood and sediment management at the river-basin scale.

As a global contribution to flood and sediment-risk reduction, the Kantoush Lab has initiated research on “wadi” flash-floods in the Middle East and North Africa (MENA) region. A wadi is an Arabic term referring to a dry river channel or valley that behaves like a river basin during rare, intense rainfall. Arid regions in the MENA zone are often hot deserts with infrequent rainfall, but climate change is increasing the frequency and intensity of catastrophic flood events.

We also share knowledge and practices from Japan in flood and sediment management with Southeast Asian countries (Philippines, Vietnam, Singapore, Malaysia). As a result of this international collaboration, the Kantoush Lab proposes improved strategies for disaster risk reduction and water-resources management in diverse river and wadi basins.

Finally, we recognize that most river and wadi systems — at national or trans-national scales — face essentially the same challenges of flood and sediment management. Our goal is to develop unique but transferable integrated river-basin management approaches.

 

Thematic Areas of Study

1. NEXUS-Philippines: Synergistic Strategies for Sustainable Water Resources and Dam Management under Extreme Climate Variability (3S-WaRM)

This research integrates long-term ensemble rainfall predictions with ensemble climate prediction databases to forecast extreme floods linked to super typhoons and abnormal droughts caused by climate change. The goal is to enhance the operations of Magat dam for effective flood mitigation and create a web-based platform for the Cagayan River Basin to share research findings with the Philippine community.
Specifically, the Japanese team will simulate dam operations using remote sensing data and satellite imagery while downscaling of global climate predictions to regional and basin levels. The Philippine team will then incorporate these findings into policy planning, which includes developing water security indicators and master plans for local governments in the Cagayan River Basin.
Through the collaborative efforts of teams from both countries, we aim to establish new guidelines for water resource management based on hydrological predictions. Additionally, we will focus on developing human resources to implement these guidelines and strengthening adaptation measures to address the increase in extreme weather events resulting from future climate change.

 

2. Fundamental study on a Self-regulating Sediment Supply for the restoration of the sediment transport environment (3S-Project):  

In Japan and around the world, siltation in dam reservoirs has led to a progressive reduction in storage capacity, while the decrease in downstream sediment discharge has caused severe riverine environmental degradation and shoreline retreat due to the loss of sediment supply to coastal zones. As a countermeasure, sediment replenishment—the deliberate placement of sediments from reservoirs into downstream reaches—has been increasingly adopted. However, research on post-replenishment sediment dynamics and management remains limited, constraining the broader implementation of effective sediment restoration projects.
Meanwhile, climate change has amplified the frequency and intensity of extreme rainfall events, heightening the risks of sediment-related disasters, such as sediment-laden floods. To achieve both environmental restoration and flood control—that is, the “restoration of the sediment environment”—it is essential to regulate not only the quantity but also the timing of sediment transport within river channels to maintain a dynamic equilibrium.

The river-widening concept, widely implemented in Europe and especially in Switzerland, has emerged as a key nature-based solution that harmonizes flood protection with ecological restoration. The first river-widening project in Switzerland was undertaken on the Emme River in 1991 to mitigate severe riverbed incision. The project successfully stabilized the riverbed while enhancing aquatic and riparian biodiversity, establishing a pioneering model for integrated flood and ecosystem management.

Building upon these international experiences, the present study aims to investigate an integrated approach that combines river widening, sediment replenishment, and nature-based solutions to restore and sustainably manage sediment dynamics in Japanese rivers.