近50a尼洋河更张段河道形态变化分析

A comprehensive analysis of the channel morphological changes in the Gengzhang reaches of Niyang River in recent 50 years

为探究在“亚洲水塔”失衡背景下河流形态的变化及其对环境变化的响应,选取尼洋河中下游的更张河段(麦丁-加定村)为研究对象,基于1970年1∶100000地形图和1990、2000、2010、2020年4期Landsat遥感影像对该河段河道形态进行恢复,从主流线长度、心滩数量、河宽变化和曲率变化方面对河道形态参数进行分析.结果表明,该区域辫状河段占比下降,并向曲流河道转变,河道宽度变化较小,曲率相对稳定(1.28~1.40);网状河段占比稳定,曲率变化最大(1.39~1.97);曲流河段占比上升,河道宽度变化最大,曲率相对稳定(1.26~1.42).河道形态的变化与近年来“亚洲水塔”失衡带来的水沙变化以及区域内不断增强的人类活动息息相关.

In order to explore the changes in river morphology and its response to environmental changes under an unbalanced change of the"Asian Water Tower",the Gengzhang section(Mading-Jading village)of the Niyang River was selected as the research object.Based on a 1∶100000 topographic map from1970 and Landsat remote sensing images from 1990,2000,2010 and 2020,the channel morphology of the Gengzhang reaches was restored and,the influence of the length of the mainline,the total numbers of mid-channel bars,changes in the channel width and sinuosity on the river morphological changes were analyzed.The results showed that the proportion of braided river reaches in this area decreased and shifted to meandering reaches,the channel width changed slightly and sinuosity was relatively stable between 1.28-1.40;the proportion of anastomosing river reaches was stable and the sinuosity changed the most,between 1.39-1.97;the proportion of meandering river reaches increased,the channel width changed greatly and the sinuosity was relatively stable,between 1.26-1.42.The changes in river morphology were closely related to the changes in water and sand caused by the unbalanced change of the"Asian Water Tower"in recent years,as well as by the increasing human activities in this region.