{ "cells": [ { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "notes" } }, "source": [ "[LICENSE](https://raw.githubusercontent.com/computational-sediment-hyd/a-rudimentary-knowledge-of-river-bed-variation/master/LICENSE)" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "notes" }, "toc": true }, "source": [ "

Table of Contents

\n", "
" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "## 沖積河川の砂州について" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "### はじめに\n", "\n", " - 沖積河川の砂州(以降、砂州)とは、\n", "川の流れに伴う土砂移動によって形成される川幅スケールの河床地形を示す。\n", " - 川幅(堤防間の幅)やその曲率等の平面的な河川地形の影響により砂州の形状が異なる。\n", " - 日本の土砂水理関連の書籍には砂州に関する項目は必ず記述されるが、海外の書籍には記述が少ない。理由は不明。\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "### 砂州の分類\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "#### 砂州の分類" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "日本では[土木学会水理委員会移動床流れの抵抗と河床形状研究小委員会](https://www.jstage.jst.go.jp/article/jscej1969/1973/210/1973_210_65/_article/-char/ja/)\n", "で定義された次の分類を用いることが多い。\n", "
\n", "\n", "
\n", "\n", "[土砂水理学1　POD版](https://www.morikita.co.jp/books/book/1073)p.102より引用" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "また、河村は次のように整理している。\n", "
\n", "\n", "
\n", "\n", "[土砂水理学1　POD版](https://www.morikita.co.jp/books/book/1073)p.101より引用" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "#### 砂州の特徴\n", "実河川を例にそれぞれの砂州形状の特徴を簡単に示す。" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "subslide" } }, "source": [ "##### 交互砂州(単列砂州)\n", "\n", "左右交互に周期的に形成される砂州を示す。下流方向に伝播する。\n", "\n", " - 例 : 那賀川" ] }, { "cell_type": "code", "execution_count": 1, "metadata": { "hide_input": true, "slideshow": { "slide_type": "fragment" } }, "outputs": [ { "data": { "text/html": [ "\n", " \n", " " ], "text/plain": [ "" ] }, "execution_count": 1, "metadata": {}, "output_type": "execute_result" } ], "source": [ "from IPython.display import IFrame\n", "IFrame(\"https://maps.gsi.go.jp/?hc=hic#14/33.938447/134.621229/&base=ort&ls=ort%7Cgazo4&blend=0&disp=11&vs=c1j0h0k0l0u0t0z0r0s0m0f0\" ,width=800,height=400)" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "##### 多列砂州\n", "\n", "上述の交互砂州が河道内に2つ以上形成される砂州形状を示す。\n", "\n", " - 例：斐伊川" ] }, { "cell_type": "code", "execution_count": 2, "metadata": { "hide_input": true, "slideshow": { "slide_type": "fragment" } }, "outputs": [ { "data": { "text/html": [ "\n", " \n", " " ], "text/plain": [ "" ] }, "execution_count": 2, "metadata": {}, "output_type": "execute_result" } ], "source": [ "from IPython.display import IFrame\n", "IFrame(\"https://maps.gsi.go.jp/?hc=hic#16/35.414428/132.809687/&base=ort&ls=ort%7Cgazo4&blend=0&disp=11&vs=c1j0h0k0l0u0t0z0r0s0m0f0\" ,width=500,height=400)" ] }, { "cell_type": "code", "execution_count": 3, "metadata": { "hide_input": true, "slideshow": { "slide_type": "slide" } }, "outputs": [ { "data": { "text/html": [ "\n", " \n", " " ], "text/plain": [ "" ] }, "execution_count": 3, "metadata": {}, "output_type": "execute_result" } ], "source": [ "from IPython.display import IFrame\n", "IFrame(\"https://www.google.com/maps/embed?pb=!4v1589436014790!6m8!1m7!1svjLVOaONp8rfG7vPXg-Jsg!2m2!1d35.41611159377166!2d132.8138269050567!3f57.704570097648585!4f-6.681007775900639!5f0.7820865974627469\" ,width=800,height=500)" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "##### 網状流路\n", "\n", "洪水時に大きく変動しない（砂州上の流れの掃流力が小さい）砂州が部分的に出現することにより、周期性を持たない網状流路が形成される。\n" ] }, { "cell_type": "markdown", "metadata": { "hide_input": false, "slideshow": { "slide_type": "slide" } }, "source": [ " - 例：釜無川\n", "\n", "画像を右クリックで再生を選択\n", "