On the basis of the analysis of factors affecting the river water level, the BP neural network model, based on the gradient descending algorithm, is used to calculate the river water level.
在分析影响河道水位因素的基础上，采用基于梯度下降算法的BP神经网络模型推算河道水位，同时采用传统的上下游水位线性相关方法进行水位推算。
Main factors effecting on flow rate in braided river is gradient of anabranch, area of water, roughness and velocity.
影响汊道分流比的主要因素有：两汊的比降、过水断面积、糙率、流速等。
Rocky desertification in the karst region is related to stratum and lithology, incising of river, soil erosion, gradient and human activities, etc.
喀斯特地区土地的石漠化与地层岩性、河流切割、土壤侵蚀、坡度及人类活动等有关。
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