Hydrological observation of subsurface flow spouting from pipe exits in torrent bed material and its triggering rainfall condition for the prediction of debris flow generation

2014 Fiscal Year Final Research Report

• Project/Area Number: 24310137
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Natural disaster science
• Research Institution: Mie University
• Principal Investigator: YAMADA TAKASHI 三重大学, 生物資源学研究科, 教授 (20333635)
• Co-Investigator(Kenkyū-buntansha): NUMAMOTO Shinya 三重大学, 大学院生物資源学研究科, 准教授 (60324555) ; TSUCHIYA Satoshi 静岡大学, (連合)農学研究科, 教授 (60197720) ; GONDA Yutaka 新潟大学, 農学部, 准教授 (10303116)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 土石流 / 渓床堆積物 / 伏流水 / パイプ流 / 現地観測 / 発生限界基準雨量 / RBFN手法

Outline of Final Research Achievements

Several pipe exits were discovered in the torrent bed material in debris flow generation areas of the Nishinokaito River, Mount Fujiwara ,Mie prefecture, Japan. They were emplaced in a sand and gravel layer between 1.0 and 1.5 m below the surface of the torrent bed material. Gravel supported the internal walls of the pipe exits. Subsurface flows spouted when the rainfall intensity exceeded about 5 to 7 mm in 10 minutes and the soil water index exceeded about 110 mm. Hydrological processes such as subsurface flows spouting from pipe exits and its clogging, subsurface flows spouting at the new pipe exits during heavy rainfall may lead to debris flow generation. The critical rainfall thresholds for them were studied using radial basis function network (RBFN) method.

Free Research Field

砂防学、砂防工学