学术报告

题目:日本佐贺平原传统防洪对策研究

报 告 人:大串浩一郎(日本佐贺大学科学与工程研究生院土建系教授)

报告时间:2015年9月15日(星期二) 上午9:30—11:00

报告地点:清华大学人文社科图书馆格物会议室

主办单位:清华大学科技史暨古文献研究所

联系人:冯立昇教授

联系电话:62784745

內容简介

日本九州岛的佐贺低平原是典型的低地,每当暴雨降临,洪水频发,常常给居民造成很大危害。这一区域的河流水位经常受到海潮的影响。地势较高的地段有天然堤和冲积扇,也频发洪水。早在江户时代早期(17世纪)就有防洪对策,在佐贺平原的河中或河旁,都有很多防洪设施,如滞洪区、溢洪坝、防护林区、辅堤等,来控制洪水的流向和水量。不少防洪设施留存至今,一些设施仍在使用。发现并恢复这些遗迹,弄清其作用,对于今后的防洪包括汇水盆地的运行很重要。

2000年,日本河流委员会报告“有效防洪包括汇水盆地运行的理想方法”。报告里不仅讨论了普通临水设施的防洪措施,还包括超过设计水位洪水的减灾措施。佐贺平原使用汇水盆地的防洪对策使用了约400年。本研究首先使用GIS和水力计算量化评估嘉濑川流域的传统防洪技术,进而重点关注该平原的防洪历史遗存,并阐明其作用。我们进而研究城原川的溢洪坝和开口堤,估计滞洪区的控制水量和泥沙输送。对于开口堤功能的量化研究,我们采取了岩土采样法,样本类似于盆子,便于分析评估水流速度、流向和沉积过程。使用二维数值模拟,估计从溢洪坝流向滞洪区的水流,从而考虑开口堤的功能。地质勘察和水力计算的结果反映居民区滞洪区的控制水量。研究结果对于防洪包括汇水盆地运行给出了定量分析。

 

A Study on the Traditional Flood Management in Saga Plain, Japan

Koichiro Ohgushi

Department of Civil Engineering and Architecture, Graduate School of Science and Engineering, Saga University, Japan

Abstract

The lower Saga Plain of Kyushu Island, Japan is one of the typical lowland and flooding and inundations have frequently occurred inside levee and have given many serious damages to the watershed's residential area when heavy rainfall occurs in the residential area. In this area, water level of the river is usually affected by a sea tide. On the other hand, in the higher area, natural levee zone and alluvial fan are seen and river flood damages have often occurred in these areas. The countermeasure against these flood disasters have been done mainly from the early Edo period, that is, 17 century in Japan. There are many flood damage prevention facilities in the river or near the river of the Saga Plain. For examples, there had been many retarding basins, overflow embankments (Nokoshi), flood restraining forest belt, and auxiliary levees in the residential area (Mizuuke-tei), which control a direction and magnitude of flood flow. At present, several facilities of the flood control are left and can be seen as historic remains. Some flood damage prevention facilities are still effective. It is significantly useful to find out and restore these remains and clarify their functions to consider a future flood control including catchments basin operations.

In the year of 2000, the River Council in Japan intermediately reported "The ideal method of the effective flood control including catchments basin operations." In the report, they discuss not only the flood control measures by ordinary riparian works but also the disaster reduction for a flood exceeding design levels. In the Saga Plain, these countermeasures against flood by using catchment basin operation had been used about 400 years ago.

In this study, first of all, a traditional flood control technology is quantitatively evaluated in the Kase River Basin by using GIS and hydraulic calculation. And then, its usefulness is clarified by focusing on the historic remains for flood control in this plain.

Next, overflow embankments and open levees of the Jobaru River are studied as the investigated field for estimating a controlled water flow spreading the retarding basin with sediment transports.

For the detail quantitative research against the open levee functions, we adopted a geotechnical sampling method to obtain a plate-like sample that can be easily analyzed for estimating water flow velocity, flow direction and a process of sediment settling. A two dimensional numerical simulation is implemented to estimate water flow on the retarding basin from the overflow embankment to consider this open levee's functions. The results of geotechnical investigation and hydraulic approach show the controlled water flow in the retarding basin in the residential area. This result gives a quantitative consideration about the flood control including catchment basin operations.

 

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