[A-AS02] Extreme Events: Observations and Modeling

[AAS02-09] River discharge estimation of ungauged mountainous river basin using NIED Hi-net data

★Invited Papers

*Shakti P.C.¹, Kaoru Sawazaki¹ (1.National Research institute for Earth Science and Disaster Resilience (NIED))

In Japan, flood events in mountainous river basins in recent years have resulted in significant loss of life and damage to infrastructure. Estimation of peak streamflow of rivers during flood events can be a good reference for flood disaster prevention and management. However, because there are no streamflow data for many of the small mountainous river basins in Japan – known as ungauged river basins – it takes considerably more effort to predict and estimate water-related disasters in such areas. To understand the flow rate of ungauged river basins during the extreme rain event, there are several direct and indirect approaches that have been applied and tested to estimate river discharge particularly during the period of an extreme rain event.
In this study, we considered High sensitivity seismograph network (Hi-net) observation to recognize the time and peak discharge during a heavy rain event. Hi-net is a nationwide high-sensitivity seismograph network, Japan, comprised of more than 800 seismograph stations distributed by approximately 20 km distance interval. They are also located in the mountainous region to measure earthquakes. Two Hi-net stations are located in a mountainous sub-basin of the Mogami River Basin, located in Yamagata prefecture of Japan. After validating the simulated discharge data of the Mogami River Basin with gauged data for the selected two past rain events (10-23 July 2004 and 7-16 September 2015), simulated discharge of a river was compared with noise data of the Hi-net stations. It was found that the noise data of those stations at a high-frequency level were followed a similar trend with the time series of simulated discharge at those two points for the selected events.