インド・ブラマプトラ川のおける洪水と災害 Flood Dynamics and Hazard in the Brahmaputra Valley of India

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Abstract

ブラマプトラの巨大でダイナミックな河川システムにおいては,河川の自然のプロセスのみでも深刻な洪水を引き起こすのに充分である.頻発する地すべり,急な斜面,浸食されやすい岩石やヒマラヤ地区の地震のおきやすさなどは,モンスーンの多量の降水と結合してブラマトプラ川の洪水を引き起こす主要な自然の原因となる.その上,最近顕在化した人間が引き起こす原因が洪水の規模や洪水損害を増大させるのに貢献している.1955年から2000年におけるブラマプトラ川の洪水(年平均47.660 m^3s^<-1>)は2.31年の再現周期をもっており,大きな流量,高い頻度と壊滅的破壊という特徴をもっている.大きな洪水は氾濫源の地形や流路形状に大きな地形学的インパクトを与え,結果として深刻な河岸の浸食や頻繁な河谷位置の遷移をもたらす.大きな規模の洪水が繰り返して起こると壊滅的な打撃となり川沿いの農業経済に影響を与える.新しい地域への氾濫の広がりという洪水特性の変化にともない,洪水による損害の広がりや規模は最近増大している.適切な洪水調整の活動(河川管理)は川沿いの社会-経済発展の重要な要因である.

In the vast and dynamic river system of the Brahmaputra, the natural processes alone are adequate to cause severe floods. The frequent landslides, steep slopes, high erodibility of rocks and high seismicity of the Himalayan domain coupled with heavy monsoonal rain constitute the major natural causes of floods in the Brahmaputra valley. Besides, a host of recently emerging human-induced causes have also significantly contributed to an increase in flood size and damages. The Brahmaputra floods during 1955-2000 with their mean annual magnitude of 47,660 m^3s^<-1> having a recurrence interval of 2.31 years are usually characterised by large magnitudes, high frequencies and extensive devastations. The large floods have their major geomorphic impact on floodplain morphology and channel configuration resulting in severe bank erosion and frequent thalweg shifting. The recurring floods of characteristically high magnitudes assume devastating dimension heavily affecting the agrarian economy of the valley. The extent and volume of flood damages have recently risen with concomitant changes in the nature of flooding in terms of frequency and spread of inundation to new areas. A package of appropriate flood management activities is regarded as the key factor of socio-economic development of the valley.

Journal

Transactions, Japanese Geomorphological Union   [List of Volumes]

Transactions, Japanese Geomorphological Union 24(1), 65-85, 2003-01-25  [Table of Contents]

The Japanese Geomorphological Union

References:  17

Cited by:  1

Codes

  • NII Article ID (NAID) :
    110001273020
  • NII NACSIS-CAT ID (NCID) :
    AN00333248
  • Text Lang :
    ENG
  • Article Type :
    Journal Article
  • ISSN :
    03891755
  • NDL Article ID :
    6471549
  • NDL Source Classification :
    ZM49(科学技術--地球科学--地質)
  • NDL Call No. :
    Z15-386
  • Databases :
    CJP  CJPref  NDL  NII-ELS