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不同时段河道的侧向侵蚀/加积面积变化的定量研究可以揭示河道的变化特征。以黄河临河段213 km长的河段为研究对象,利用1977年以来19个时段基于遥感影像绘制的河道平面形态图的面积变化来估算其4个亚河段(S1、S2、S3和S4)在不同时段的河岸侧向侵蚀/加积面积以及全河段的河道平均萎缩速率。研究结果表明,黄河临河段左右河岸在37年间都表现为侧向净加积,其4个亚河段左岸的侧向累计加积面积分别为33.16 km~2、49.59 km~2、29.52 km~2和30.85 km~2,其中1995-2000年的加积面积分别占到其总加积面积的85.5%、51.2%、47.2%和104.6%;右岸的侧向累计加积面积分别为30.83 km~2、8.74 km~2、26.44 km~2和18.76 km~2,而1995-2000年的加积面积分别占到其总加积面积的57.2%、111.9%、65.7%和61.6%。该河段河道面积1977-2001年具有减小趋势,2001年之后河道表现为侧向侵蚀、加积的交替变化,1977-2014年间河道平均萎缩速率为6.16 km~2/yr。该河段河道平面形态值最明显的变化也发生在1990s,与1995年相比,2000年的河道长度增加了5.8%,河道面积减少了39.4%,河道平均宽度减小了42.8%,弯曲系数增加了6.6%。黄河临河段河道形态剧烈变化及河道严重萎缩都发生在1990s,这主要是黄河上游刘家峡和龙羊峡水库联合运行导致汛期水沙量大量减小所致,4个亚河段的河岸冲淤变化还受到局部河岸物质结构、护岸工程及水动力差异的影响。随着2000年后河流综合管理措施的调整,黄河临河段河道的上述变化趋势明显弱化,河流健康程度有所好转。
The quantitative study of the lateral erosion / accumulation area changes at different time intervals can reveal the variation characteristics of the river course. Taking the 213 km long section of the Linhe section of the Yellow River as the research object, four sub-river sections (S1, S2, S3 and S4) were estimated based on the area changes of the riverbed planimetric plots drawn from remote sensing images in 19 periods since 1977. River bank lateral erosion / accretion area at different periods and the average river channel atrophy rate across the river. The results show that the lateral banks of Linhe reach of the Yellow River show a net lateral accretion in 37 years, and the accumulative lateral accumulative accumulative area of the left bank of the four sub-reaches are respectively 33.16 km ~ 2,49.59 km ~ 2,29.52 km ~ 2 and 30.85 km ~ 2, respectively, of which the accretion area from 1995 to 2000 accounted for 85.5%, 51.2%, 47.2% and 104.6% of the total accreted area, respectively. The accumulative lateral accumulative area of the right bank was 30.83 km ~ 2,8.74 km ~ 2,26.44 km ~ 2 and 18.76 km ~ 2, while the accretion area from 1995 to 2000 accounted for 57.2%, 111.9%, 65.7% and 61.6% of their total accreted area respectively. The river channel area decreased from 1977 to 2001, and after 2001 the river channel showed lateral erosion and alternation. The average river avalanche rate from 1977 to 2014 was 6.16 km 2 / yr. The most obvious change of river channel shape value occurred in the 1990s. Compared with 1995, the length of the river channel in 2000 increased by 5.8%, the river channel area decreased by 39.4% and the mean width of the river channel decreased by 42.8%. The bending coefficient An increase of 6.6%. The drastic changes of channel shape and severe channel atrophy in the Linhe section of the Yellow River occurred in the 1990s. This is mainly caused by the joint operation of the Liujiaxia and Longyangxia reservoirs in the upper reaches of the Yellow River, resulting in a large decrease in the amount of sediment and sediment in the flood season. But also by the local river bank material structure, bank protection project and hydrodynamic differences. With the readjustment of comprehensive river management measures after 2000, the above-mentioned trend of river course in Linhe section of the Yellow River obviously weakened, and the river health improved.