The stream flow generation method is necessary for predicting yearly bed change at an ungauged stream in Monsoon region where there is no hydrologic and hydraulic information. This study developed the stream flow generation method of daily mean flow for each month over a year for bed change simulation at an ungauged stream. The hydraulic geometries of cross-sections and the corresponding bankfull indicators of the Byeongseong river of 4 km reach were analyzed to estimate the bankfull discharge. The estimated bankfull discharge of the target reach was 77.50 m³/s, and the total annual discharge estimated 3720 m³/s through the correlation equation with the bankfull discharge. The measured total annual discharge of the Byeongseong river was 3887.30 m³/s, which is greater by 167.30 m³/s of 4.3% relative error. The volume and bed changes over a year by the Center for Computational Hydroscience and Engineering Two-Dimension (CCHE2D) model simulated using the measured discharge during 2013 and 2014 coincided with the surveyed in the same period. Estimated total annual discharge was used for the scenarios of stream flow generation. The generated stream flow using the flow apportioned to each month on the basis of the flow percentage in an adjacent stream simulated the river bed most appropriately. The generated stream flow using the flow based on the monthly rainfall percentage of the rainfall station in the target stream basin also simulated river bed well, which is confirmed as an alternative. Quantitatively, the root mean square error (RMSE), mean bias error (MBE), and mean absolute percentage error (MAPE) in-depth change of thalweg between the measured and the simulated were found to be 0.25 m, 0.04 m, and 0.44%, respectively. The result of the simulated cross-sectional river bed change for target reach coincided well with the surveyed. The proposed method is highly applicable to generate the stream flow for analyzing the yearly bed change at an ungauged stream in Monsoon region.

中文翻译：

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模拟季风区无塞流的年河床变化的流产生

对于没有水文和水力信息的季风地区，在未引流的情况下预测河床的年变化是必要的。这项研究开发了一种一年中每月每月平均流量的流量生成方法，用于在未开启流量下模拟河床变化。分析了京城河4 km河段的横断面水力几何形状和相应的河床流量指标，以估算河床流量。通过与堤岸满流量的相关方程，估计的目标河岸满流量为77.50 m ³ / s，年总排放量估计为3720 m ³ / s。测算的平城河年总排放量为3887.30 m ³/ s，大于167.30 m ³/ s的相对误差为4.3％。计算水科学与工程二维中心（CCHE2D）模型使用2013年和2014年的实测排放量模拟的一年中的体积和床层变化与同期的调查相吻合。估算的年总排放量用于产生水流的情景。使用基于相邻溪流中流量百分比分配给每个月的流量生成的溪流最合适地模拟了河床。使用基于目标流域降雨站每月降雨百分比的流量生成的水流，也模拟了河床井，这被证实是一种替代方法。从数量上讲，均方根误差（RMSE），均值偏差误差（MBE），实测值与模拟值之间的thalweg深度平均绝对百分比误差（MAPE）深度变化分别为0.25 m，0.04 m和0.44％。目标河段的模拟断面河床变化结果与实测吻合得很好。所提出的方法非常适用于产生气流，以分析季风区未引流的年河床变化。