DEM分辨率对山洪淹没模拟影响

DEM是表征地形状况的重要指标,在山洪淹没模拟中起着重要作用。以2016年7月19日发生在河北省石家庄市井陉县西部山区的特大暴雨山洪事件为研究对象,利用HEC-HMS水文模型和FLO-2D水动力模型,设置5种DEM分辨率方案(30、20、15、10、5 m),从淹没范围和淹没水深两方面分析了DEM分辨率对山洪淹没模拟的影响,并从模型运行时间角度对其运行效率进行了评估。研究表明:DEM分辨率越高,则淹没范围越小,平均淹没水深越大,即模型模拟精度越高,山洪事件的淹没范围及水深越接近于实际调查情况(DEM分辨率为30和5 m时,淹没范围及淹没深度的模拟精度分别为0.56和0.41、0.76和0.79);随着DEM分辨率的提高,尤其从10 m提高至5 m时,模拟结果差异减少,模拟精度的增幅也减小,淹没范围和水深的精度增幅分别为2.70%和3.94%;DEM分辨率越高,则模型运行时间越长,模型运行效率越低,5 m DEM方案下的运行时间为30 m DEM方案的700倍。综合考虑模拟精度及模拟时间,10 m分辨率的DEM对山洪淹没模拟、风险评估及预警预报等更为适用。     

HEC-HMS模型在城市化流域洪水模拟中的应用

流域城市化过程影响了城市洪水形成的产汇流条件,显著增大了流域洪水模拟预报难度。采用HECHMS水文模型,选取秦淮河流域城市化前1980~1988年间共8场降雨-径流过程、城市化后2007~2013年间共7场降雨-径流过程开展洪水模拟研究,率定城市化前后不同土地利用情景下的产汇流参数,并设计城市化影响洪水模拟方案,对比分析城市化影响下的流域水文响应。结果表明:HEC-HMS模型在秦淮河流域城市化前后均具有很好适用性,且单峰洪水过程模拟精度高;城市化后流域内其他用地向城市建设用地转移,流域内不透水面积增加明显,使得产流量增加,洪峰流量增大,峰现时间提前约2 h。     

基于LUCC的秦淮河流域暴雨洪水响应分析

利用CA-Markov模型预测流域2028年土地利用情况,设置3种土地利用情景(自然发展情景、林地限制情景、水田限制情景),建立研究区HEC-HMS水文模型,研究秦淮河流域高速城市化背景下土地利用变化的暴雨洪水响应机制。结果表明①HEC-HMS模型适用于研究区洪水模拟及不同土地利用情景下的洪水响应研究;②洪水规模越小,对土地利用变化的洪水响应越强;③随着流域城市化的演进,土地利用对暴雨洪水的影响程度呈增大趋势,其中自然发展情景下的增加程度最大,水田限制情景次之,林地限制情景最低。研究成果为秦淮河流域LUCC的暴雨洪水响应分析提供了新的思路,也对流域防洪规划与建设有一定的指导意义。     

参数变化对HEC-HMS模型流域洪水模拟结果的影响

为分析圩院式防洪模式对流域防洪的影响,以秦淮河流域为研究区,构建HEC-HMS水文模拟模型,分析不透水率、允许水深、排涝模数的变化对流域洪峰和洪量模拟结果的影响。研究结果表明:随着流域不透水率从20%增大至70%时,圩垸式防洪模式下流域洪量和洪峰均呈现增大趋势;当圩垸允许水深增大时,圩垸式防洪模式下流域洪量呈递减趋势,而流域洪峰呈递增趋势;随着排涝模数的降低,流域的洪峰和洪量呈递减趋势。研究成果对秦淮河流域及相似流域的HEC-HMS模型洪水模拟及参数设置具有借鉴和指导意义。     

山丘区小流域下垫面数据精度对HEC-HMS水文模拟的影响研究

山丘区小流域下垫面条件复杂多变,DEM分辨率及子流域划分水平对分布式水文模型模拟结果的影响有待深入研究。本文选取小流域应用广泛的HEC-HMS分布式水文模型,在河南省栾川流域设置四种DEM分辨率方案及四种子流域划分方案,分别提取不同方案下的流域水文特征参数进行对比,并分析两种类型的数据精度对纳什系数和峰值模拟的影响。研究结果表明,与大中流域相比,DEM分辨率和子流域划分对山丘区小流域空间参数和水文模拟结果的影响要更为显著。在实际山洪预警预报工作中,为保证模拟结果的稳定性和可靠性,应尽可能选择高精度下垫面数据精度。     

HEC—HMS模型在清江流域洪水模拟中的应用

HEC—HMS模型是一个半分布式的水文模型,它和它的子模块HEC—GeoHMS模型一起用来进行洪水模拟。首先,由HEC—GeoHMS处理流域DEM数据,生成包含水文信息的HEC—HMS能接受的降雨输入信息;然后将该信息导入HEC—HMS模型中,征HEC—HMS模型中建立包含流域产汇流模块的流域模型,包括雨量气象信息的气象模型,和包含模拟时间控制的控制模型;最后率定各子模型中的参数。以清江流域为例,运用HEC—HMS模型对6场洪水过程进行了模拟,模拟结果表明对次洪径流过程的模拟精度较好。     

A physically based and machine learning hybrid approach for accurate rainfall-runoff modeling during extreme typhoon events

Accurate rainfall-runoff modeling during typhoon events is an essential task for natural disaster reduction. In this study, a novel hybrid model which integrates the outputs of physically based hydrologic modeling system into support vector machine is developed to predict hourly runoff discharges in Chishan Creek basin in southern Taiwan. Seven storms (with a total of 1200 data sets) are used for model calibration (training) and validation. Six statistical indices (mean absolute error, root mean square error, correlation coefficient, error of time to peak discharge, error of peak discharge, and coefficient of efficiency) are employed to assess prediction performance. Overall, superiority of the present approach especially for a longer (6-h) lead time prediction is revealed through a systematic comparison among three individual methods (i.e., the physically based hydrologic model, artificial neural network, and support vector machine) as well as their two hybrid combinations. Besides, our analysis and in-depth discussions further clarify the roles of physically based and data-driven components in the proposed framework.     

基于HEC-HMS的西南山区中小河流洪水预报研究

针对目前中小河流洪水预报难度较大、预报精度偏低的问题,以西南山区荥经河流域为例,基于HECHMS构建了荥经河流域分布式水文模型,以2009~2018年23场洪水进行参数率定,4场洪水进行模型验证。通过参数敏感性分析和有效率定,模拟的洪水过程与实测洪水过程吻合较好,其中模拟洪峰流量平均误差为6.81%,平均纳什效率系数为0.84。可见构建的HEC-HMS洪水预报模型对荥经河流域有很好的模拟效果,可为西南山区其他中小河流的洪水预报提供借鉴和参考。     

HEC-HMS模型和TOPMODEL模型在东庄流域山洪预报的应用研究

水文模型是山洪预报的理论依据,不同模型间的结构、适用性、精度均不同。为探究HEC-HMS模型和TOPMODEL模型的特性及其模拟效果的差异,选取东庄流域10场代表性洪水,以峰现时间误差、径流深误差、时间误差和确定性系数为检验指标,进行场次洪水模拟。结果表明,两模型的预报方案在东庄流域模拟中各评定指标均达标,率定期均为甲等精度,验证期均为丙等精度。HEC-HMS模型和TOPMODEL模型对蒸散发的差异性参考,使得在半干旱区HEC-HMS模型的适用性更好。研究成果对于HEC-HMS模型和TOPMODEL模型在该区域的应用及防灾减灾有重要意义。     

Flood Intensification due to Changes in Land Use

The non-stationarity in runoff regime may be attributed to various causes such as climate change, land use change, and man-made runoff control structures. Degradation of land use can induce significant impact on infiltration and surface roughness leading to higher flood discharges. This study aims at quantifying possible effects of land use changes and identifying flood source areas for future flood control planning in the Golestan watershed located northeast of Iran. A preliminary trend analysis on the annual maximum flood record of three stations inside the watershed showed that two stations were subject to anthropogenic change. This is while no trend could be detected in the annual maximum rainfall records in the region. Using a calibrated event-based rainfall-runoff model, flood hydrographs corresponding to land use conditions in 1967 and 1996 were simulated and relative changes in the peak flow of the two subsequent conditions were determined for different return periods. The results showed that the impact of land use changes on the flood peak discharge is considerably greater in some subwatersheds. Two limiting land use scenarios were also considered to investigate the envelope of future flood peaks in the watershed. By successively eliminating subwatersheds from the simulation process in a method titled "unit flood response”, the contribution of each subwatershed to the outlet flood peak was quantified. Contribution, per unit area, to the outlet flood peak was the basis to rank the subwatersheds in terms of their flood potential.