臺灣河川輸沙特性及其地形意義

作者:黃朝恩(國立臺灣師範大學理學院物理系)

摘要：

本研究旨在究明臺灣河川之輸沙特性及其相關現象。分析所依據者乃全省四十九個主要流域及七十六個水文站之累年輸沙記錄，並以地形計測、野外實察及統計處理等研究方法配合進行。所獲資料有助於吾人對台灣河川輸沙之強度、規模、作用、空間差異以至時間變遷等之認識，由此達成多項結論。為求條理分明，全文乃針對下列四項題先後闡述：(1)輸沙量及含沙量之特性；(2)物理剝蝕率之推估；(3)輸沙及流域形態之關係；(4)輸沙及流域營力間之關係。由種種證據觀之，均顯示臺灣地區的輸沙問題至為嚴重，尤其就單位面積輸沙量而言，各大河川在10000M.T./km2/yr以上者比比皆是，二仁、曾文、濁水諸溪流域更超過20000M.T./km2/yr，高出世界上其他大河甚多。再看物理剝蝕率，全島平均每千年為3526mm，正代表著臺灣自然環境的獨特性。至於輸沙和其他流域特徵之間，每每呈現密切之關係，例如年逕流量及年輸沙量之相關係數更高達+0.8159，證實流域系統中確有其動力均衡特性。另由輸沙－流量關係加以深入分析，更發現二者呈現C=aQ^b之方程式，惟各集水流域之經驗公式並不一致，隨時、空而異，本文乃以a值及b值為準，將輸沙－流量關係分為六大型，得之各型均有其空間及中之趨勢，故在處理台灣地區的輸沙問題時，區域觀念確實不容忽視。

《詳全文》

Suspended Sediments of Taiwan Rivers and Their Geomorphological Significance

Author: Hwang Chao-en(Earth Science Section Department of Physics College of Sciences )

Abstract：

The paper is intended to study the suspended load of Taiwan rivers and its related features. Basic data from 49 drainage basins and 76 hydrologjcal stations are used for the analysis and conclusions are drawn with the assistance of data interpretation as well as morphometry, field observation and statistical treatment. The discussion is emphasized on the basis of its geomorphological aspects, so that the intensity, magnitude, process, spatial variation and changes in time of sediment phenomena are studied in detail. Major topics of concern include: ( 1 ) amount of sediment content and sediment yield, ( 2 ) rate of physical denudation, ( 3 ) interrelationships between sediment and basin forms, ( 4 ) interrelationships between sediment and basin processes. Then, the sediment-discharge relationship is chosen as a topic of further discussion. It is found that this relationship in Taiwan conforms to the equation C = aQ^b . According to both a and b values, Taiwan watersheds can be classified into several types with different sediment-discharge relationship. They have areal differentiation so significant that when sediment problems are handled, such regional concept should not be neglected.