Hydraulic model with roughness coefficient updating method based on Kalman filter for channel flood forecast

A real-time channel flood forecast model was developed to simulate channel flow in plain rivers based on the dynamic wave theory. Taking into consideration channel shape differences along the channel, a roughness updating technique was developed using the Kalman filter method to update Manning＇s roughness coefficient at each time step of the calculation processes. Channel shapes were simplified as rectangles, triangles, and parabolas, and the relationships between hydraulic radius and water depth were developed for plain rivers. Based on the relationship between the Froude number and the inertia terms of the momentum equation in the Saint-Venant equations, the relationship between Manning＇s roughness coefficient and water depth was obtained. Using the channel of the Huaihe River from Wangjiaba to Lutaizi stations as a case, to test the performance and rationality of the present flood routing model, the original hydraulic model was compared with the developed model. Results show that the stage hydrographs calculated by the developed flood routing model with the updated Manning＇s roughness coefficient have a good agreement with the observed stage hydrographs. This model performs better than the original hydraulic model.

Using modified Soil Conservation Service curve number method to simulate the role of forest in flood control in the upper reach of the Tingjiang River in China

To improve flood control efficiency and increase urban resilience to flooding,the impacts of forest type change on flood control in the upper reach of the Tingjiang River(URTR) were evaluated by a modified model based on the Soil Conservation Service curve number(SCS-CN) method. Parameters of the model were selected and determined according to the comprehensive analysis of model evaluation indexes. The first simulation of forest reconstruction scenario,namely a coniferous forest covering 59.35km^2 is replaced by a broad-leaved forest showed no significant impact on the flood reduction in the URTR. The second simulation was added with 61.75km^2 bamboo forest replaced by broad-leaved forest,the reduction of flood peak discharge and flood volume could be improved significantly. Specifically,flood peak discharge of 10-year return period event was reduced to 7-year event,and the reduction rate of small flood was 21%-28%. Moreover,the flood volume was reduced by 9%-14% and 18%-35% for moderate floods and small floods,respectively. The resultssuggest that the bamboo forest reconstruction is an effective control solution for small to moderate flood in the URTR,the effect of forest conversion on flood volume is increasingly reduced as the rainfall amount increases to more extreme magnitude. Using a hydrological model with scenarios analysis is an effective simulation approach in investigating the relationship between forest type change and flood control. This method would provide reliable support for flood control and disaster mitigation in mountainous cities.

Research and Application of Water Flooding Timing and Method for Blocky Bottom Water Fractured Buried Hill Reservoir

Oilfield A is a fractured buried hill reservoir in Bohai bay of China. In order to solve the difficult problem of water flooding timing and method in oilfield. Considering the characteristics of the buried hill fractures with stress sensitivity and strong heterogeneity, the ECLIPSE software was used in the research, and a three-dimensional injection-production numerical model for horizontal wells in buried hill reservoirs is established. According to the main research factors in water flooding, a series of water flooding schemes are designed, and the optimization of water flooding timing, oil recovery rate and water flooding mode in buried hill reservoirs were carried out. The results show that the optimum pressure level of fractured reservoir is about 70% of the original reservoir pressure. The optimal water flooding method is the conventional water flooding in the initial stage, when the water cut reaches 80%, it is converted into periodic water flooding. The oil recovery is the highest when the water injection period is 4 months. Field tests show that conventional water flooding is carried out in the initial stage of the oilfield A when the pressure is reduced to 70% of the original. Periodic water flooding is carried out when water cut is 80%. Good development results had been achieved in the 10 years since oilfield A was put into production. The average productivity of single well reached 300 m3/d in the initial stage, at present, the water cut is 60%, and the recovery degree is 18.5%, which is better than that of similar oilfields. This technology improves the water flooding effect of blocky bottom water fractured dual media reservoirs in metamorphic buried hills, and provides a reference for the development of similar reservoirs.

湖北省城市洪涝灾害韧性时空演变及驱动因素分析

洪涝灾害是湖北省主要自然灾害之一。开展湖北省城市洪涝灾害韧性研究,可加快该地区韧性城市建设,促进城市的可持续健康发展。以湖北省17个城市为研究对象,选取2010-2021年为研究期,从压力、状态、响应等维度构建城市洪涝灾害韧性评价指标体系,运用CRITIC-熵权组合赋权法分析其洪涝灾害韧性时空演变,并利用空间自相关法分析其洪涝灾害韧性空间集聚特征,再用地理探测器模型分析其驱动因素。结果表明:①研究期内湖北省城市洪涝灾害韧性指数呈波浪式上升趋势,增幅达34.82%;②城市洪涝灾害韧性的空间分布主要呈现为“西高东低”和以武汉为高值向外递减,城市洪涝灾害韧性的空间集聚效应较强;③城市洪涝灾害韧性的空间分异性为多因素共同作用。其中,人口暴露程度、地形起伏情况、地表陡缓程度、医疗保障能力为主要驱动因素。研究结果可为城市防洪减灾政策提供参考。

基于HEC-RAS的陇南山地山洪灾害风险图优化研究

短历时山洪是威胁陇南山地交通和村镇安全的重要灾害之一。为提高该地区防灾减灾能力,通过不同雨强计算出洪水淹没损失程度,利用洪水风险区划图指导当地群众预防山洪灾害具有重要的科学意义。基于HEC-RAS水文分析方法,结合GIS软件模拟了流域洪水淹没过程,以陇南山地蒲家沟为研究对象,在5、10、50、100 a一遇设计雨量条件下,综合考虑坡度、土地类型、损失率、水位和流速等多种因素,对传统洪水风险区划图进行优化。结果表明,相比传统方法绘制的风险区划图,优序图法优化后的风险区划图更加重视承灾体的受影响程度,且解决了传统风险区划图中小区域风险等级跨度大,风险等级难以定级的缺点。优化后的风险区划图,上中游无人区风险等级降低,下游人类活动区域风险等级更加明确。以马泉村王家咀为例,在50 a一遇的设计雨量下,传统方法绘制的风险区划图其划分结果涵盖5个风险等级,各区域面积差距不显著,难以确定最终的风险等级。而优序图法优化后的风险区划图划分结果更加集中,王家咀高风险区域面积不足中风险的4%,王家咀风险区域可以明确地定位到中风险。文中优序图法优化后的风险区划图在实用性和适应性上更具优势,可以为小流域山洪预警预报和防灾减灾工作提供帮助。

基于Copula函数的多站洪水过程随机模拟研究

洪水过程随机模拟能够生成大量与历史洪水统计参数相似且形状各异的洪水过程,而水库群联合防洪调度需要结合流域内各水文站洪水过程统筹洪水资源的调度,实现洪水资源的科学调度,亟需发展多站洪水过程随机模拟方法。鉴于此,提出一种基于Copula函数的多站洪水过程随机模拟方法,该方法先利用二维Copula函数完成主站洪水过程的模拟,然后利用条件混合法构建三维Copula函数,依次模拟其余站的洪水过程。以长江中上游8处水文站为研究对象的结果表明,各站模拟洪水与历史洪水统计参数的相对误差较小,除了北碚和武隆站的最大值外,各水文站统计参数的相对误差在5%左右,能够反映历史洪水过程的统计特征,能够为水利工程防洪规划设计、水库群联合调度及防洪调度风险分析等工作提供支撑作用。

Assessing Flood Hazard at River Basin Scale: Comparison between HECRAS-WMS and Flood Hazard Index (FHI) Methods Applied to El Maleh Basin, Morocco

The cartography of floods by two different approaches enabled us to determine the limits and the advantages of each one of them. This cartography has been applied to the El Maleh basin situated in the South-East of Morocco. The HEC-RAS approach consists of a combination of the surface hydrologic model and the digital terrain model data. This combination allows thereafter the mapping of the flood zones by the use of the WMS software. Thus it can predict the probability occurrence of floods at various frequency times and determine the intensity of the flood (depth and velocity of flood water) inside the El Maleh river by using the existing hydrological data. Otherwise FHI method approach introduces a multi-criteria index to assess flood risk areas in a regional scale. Six parameters (flow accumulation, distance from drainage network, drainage network density, slope, land use, and geology) were used in this last method. The relative importance of each parameter for the occurrence and severity of flood has been connected to weight values. These values are calculated following an Analytical Hierarchy Process: AHP, a method originally developed for the solution of Operational Research problems. According to their weight values, information of the different parameters is superimposed, resulting to flood risk mapping. The use of the WMS model allowed us to accurately map the flood risk areas with precisely flood heights in different levels. However, this method is only applicable for a small portion of the basin located downstream of the hydrological station. Otherwise, the FHI method allows it to map the entire basin but without giving an indication of the water levels reached by floods. One method does not exclude the other since both approaches provide important information for flood risk assessment.

基于马斯京根法的区间洪水推求方法

针对马斯京根法的蓄量系数K和楔蓄系数X在流域上游有水库控制时难以通过实测资料率定的问题,通过建立K、X与河道水力特征间的关系估算K、X,并采用马斯京根法将上游来水演算到下游,用下游洪水扣除上游演算到下游的洪水得到区间洪水。沭河流域青峰岭水库、小仕阳水库至莒县区间洪水的实例推求结果表明:基于马斯京根法的区间洪水推求方法与新安江模型法推求的区间洪水过程差别较小,但前者进行参数估计时可考虑不同来水河段水力特征的差异。

Comparison of SCS and Green-Ampt Methods in Surface Runoff-Flooding Simulation for Klang Watershed in Malaysia

The main aim in this research is comparison the parameters of some storm events in the watershed using two loss models in Unit hydrograph method by HEC-HMS. SCS Curve Number and Green-Ampt methods by developing loss model as a major component in runoff and flood modeling. The study is conducted in the Kuala Lumpurwatershed with674 km2 area located in Klang basin inMalaysia. The catchment delineation is generated for the Klang watershed to get sub-watershed parameters by using HEC-GeoHMS extension in ARCGIS. Then all the necessary parameters are assigned to the models applied in this study to run the runoff and flood model. The results showed that there was no significant difference between the SCS-CN and Green-Ampt loss method applied in the Klang watershed. Estimated direct runoff and Peak discharge (r = 0.98) indicates a statistically positive correlations between the results of the study. And also it has been attempted to use objective functions in HEC-HMS (percent error peaks and percent error volume) to classify the methods. The selection of best method is on the base of considering least difference between the results of simulation to observed events in hydrographs so that it can address which model is suit for runoff-flood simulation in Klang watershed. Results showed that SCS CN and Green-Ampt methods, in three events by fitting with percent error in peak and percent error in volume had no significant difference.

基于D-S证据理论改进AHP-熵权的流域洪涝灾害评估研究

考虑致灾因子危险性、孕灾环境敏感性以及承灾体易损性,选取指标构建小清河流域洪涝灾害风险评估指标体系,提出一种基于D-S证据理论的改进AHP-熵权法计算指标权重,求取洪涝灾害风险指数,运用自然断点分级法确定洪涝灾害风险等级,分析小清河流域洪涝灾害风险空间分布情况。结果表明:小清河流域洪涝灾害风险总体上表现出南低北高的趋势,其中高风险区和较高风险区分别占流域面积的8.7%和14.3%,主要分布在小清河干流以及主要支流两岸。所得评估结果同“利奇马”台风发生期间实际洪灾风险分布情况一致,对比证明基于D-S证据理论的改进AHP-熵权法优于AHP和熵权法,可为小清河流域防洪减灾决策提供依据。

水淹图书档案的抢救方法与处理技术研究

水灾会给图书档案等纸质文献带来巨大的损失,但是如果收藏主体或救援机构及时应对,采用最优的方法进行抢救和处理,不仅可以挽救图书档案,也更节省人力、物力和时间。文章聚焦于水灾发生后的时间段,以实用性为出发点,着重讨论在应对和恢复两个阶段中,工作人员如何清理受灾现场、评估灾害状况、准备抢救物资、搬运图书档案,如何对纸质文献进行冷冻;并总结了7种干燥方法的所需条件、干燥原理、优缺点,详细介绍了自然风干法和真空冷冻干燥法的操作环节,以期为收藏机构和个人提供行动指南,为制定和更新应急预案提供借鉴。

考虑淹没区域危险度的溃坝洪灾避难场所选址评价

针对溃坝洪灾避难场所选址中对潜在淹没区域危险程度重视不足的问题,提出了一种新的溃坝洪灾避难场所选址评价模型。首先,在构建危险度评价指标体系的基础上,运用改进突变评价法对潜在淹没区域进行危险度评价和危险等级划分;其次,将避难场所与高级别危险区的距离作为选址评价指标,并考虑避难场所的灾害风险、位置规模、应急保障等条件,通过层次分析法确定权重,运用TOPSIS法对避难场所进行选址评价;最后,以我国陆浑水库下游13个潜在淹没区域和10个备选避难场所为例进行验证。结果表明:危险等级较高的潜在淹没区域中,白元镇为Ⅰ级危险区,彭婆镇、鸣皋镇、城关街道、龙门镇为Ⅱ级危险区,评价较优的备选避难场所能够满足重视高危险度潜在淹没区域的要求。

岩溶山区小流域水库工程设计洪水计算——以WL水库工程为例

为科学合理确定岩溶山区小流域水库工程设计洪水,以WL水库为研究对象,考虑坝址以上伏流区、明流区分布,按全面积法、分块叠加法分别计算设计洪水,经综合比较确定坝址推荐设计洪水过程。结果表明,分块叠加法计算的设计洪水成果与坝址下游历史洪水调查成果较接近,能反映伏流区对坝址洪水调节的实际情况,并与区域已有洪水成果协调,为该工程坝址推荐设计洪水成果。本研究成果对开展区域岩溶山区水库设计洪水计算工作有一定的借鉴意义。

洪涝风险与发展潜力视角下村庄居民点布局优化——以福建省长汀县为例

全球气候变化加剧和城镇化快速推进使得洪涝灾害发生频率和破坏性显著升高,为应对洪涝灾害利用风险评估指导村庄居民点布局优化,以福建省长汀县为例,运用模糊综合评价方法划定洪涝风险等级区,通过双重目标决策法对村庄灾害风险和发展潜力进行综合评价,并基于引力模型确定村庄迁移方案。结果表明,长汀县洪涝灾害高风险区域主要分布在以汀州镇与大同镇为主体的集中建设区及以部分村庄居民点,针对高风险村庄居民点,以“避灾”为导向提出了村庄迁移合并方案,实现了村庄居民点布局的适灾和减灾优化调整。对于区域防控洪涝灾害、减少灾害损失具有重要作用,对山地村庄空间防灾减灾规划实施有较强指导意义。

基于四维度模型的湖南省湘江流域洪涝灾害风险评估

当前极端气候事件频发,降水频次与强度剧增,致使区域洪涝风险提高。为了降低区域洪涝风险,从致灾因子危险性、孕灾环境敏感性、承灾体脆弱性和防灾减灾能力四维度分析洪涝灾害风险的形成机理,基于11项指标,综合运用ArcGIS地理信息软件与熵权法等数理统计方法客观赋权,对湖南省湘江流域的洪涝风险进行综合性评估,最终制作出区县尺度的洪涝风险分布图。结果表明:湘江流域中西部致灾因子危险性低,中游地区孕灾环境敏感性高;环长株潭地区与衡阳市的承灾体脆弱性较高,但前者凭借良好的经济基础,其防灾减灾能力相对较强;湘江流域洪涝风险分布从东北向西南呈增强趋势,高洪涝风险区位于长沙市、益阳市、衡阳市及永州市南部,不同地区洪涝风险的主导因子不同。研究结果较好地反映了多因子作用下地区洪涝风险的差异,可为区域防洪减灾提供支撑。

高密度电法在汛期堤防渗漏隐患探测中的应用

汛期高水位、高渗透压力下,会造成堤防渗漏缺陷扩大或隐患加剧,快速、准确地开展堤防渗漏隐患应急排查,是指导科学防汛、保障安全度汛的重要举措。针对管涌、散浸、穿堤建筑物等渗漏缺陷及隐患,开展了高密度电法的场地试验,得到汛期堤岸的电性结构,通过比对试验,得到不同渗漏缺陷与无显著缺陷堤岸的电性差异,以此为基准,采用高密度电法对子牙河右堤天津静海段特别是子牙河汇入独流减河段进行隐患排查,划分了渗漏隐患区和潜在风险区,为保障海河流域“23·7”特大洪水期间堤防安全提供了重要技术支撑。

融合ARIMA模型和MCMC方法的非一致性设计洪水计算

常规非一致性频率分析方法在选择协变量、建立统计参数与协变量的函数关系方面均存在主观性,且仅获得设计洪水估计值,不能同时进行不确定性分析。为改进上述不足,建立了ARIMA-MCMC模型,在贝叶斯MCMC方法抽样过程中考虑统计参数拟合期内的时变性,进而对未来气候变化条件下的非一致性设计洪水频率分布模型参数进行抽样,基于参数后验分布进行设计洪水计算,并推求相应的置信区间。选取雅砻江流域小得石水文站作为分析对象,采用ARIMA-MCMC模型定量评估未来气候变化条件下小得石站设计洪水的变化情况。结果表明:基于ARIMA-MCMC方法的参数抽样收敛效果较好,3种情景下的模型统计量D均小于显著水平5%的临界值;除SSP2-4.5情景下P=0.1%和P=0.05%的设计值外,其他情况的设计最大日流量较历史期均明显增加,其中SSP1-2.6、SSP5-8.5情景下的增幅分别为7.1%~10.5%、13.9%~27.2%。本文建立的ARIMA-MCMC方法能够有效进行非一致性设计洪水频率分析。

HEC-HMS水文模型不同降雨损失方法对比研究

为对比分析HEC-HMS模型三种降雨损失方法在沁河流域的适用性。借助Morris筛选法识别降雨损失方法的关键参数,选用流域内5场雨洪资料进行参数率定和模拟精度分析。结果表明:(1)SCS CN值曲线法、Green-Ampt法、Initial and Uniform法主要敏感性参数分别为CN值、土壤饱和导水率、恒定损失率。(2)选取洪峰流量、洪水总量、峰现时刻误差以及Nash系数对模型模拟精度进行评价,SCS CN值曲线法和Initial and Uniform法模拟结果达到乙等精度,Green-Ampt法模拟结果达到丙等精度。研究成果可为半湿润地区中小流域降雨损失方法的选择提供参考。

济南市主城区城市洪涝风险分析

随着经济社会的高速发展和城市化进程的不断推进,我国多数大中城市面临着严峻的城市洪涝问题,构建科学合理的洪涝风险评价体系对政府制定防洪减灾政策至关重要。以济南市主城区为例,构建元胞自动机CAflood模型,基于模拟结果,耦合指标体系法和数值模拟法,结合层次分析法和熵权法计算的组合权重,构建新的洪涝风险评价体系,评估主城区不同暴雨情景下洪涝风险。结果表明,综合熵权法与层次分析法的组合赋权法能够结合各方法的主客观优势,较单一赋权方法更加科学合理;区划结果表明,高风险区与济南市历史洪涝灾害伤亡地点高度吻合,新评价体系在济南市洪涝风险区划中具有较高的适用性;随着重现期增大,中风险及以上风险等级面积不断增加。其中,高风险面积变化对重现期为5~10年降雨变化最为敏感,建议济南市在遭遇这一重现期暴雨时,防汛部门重点关注高风险区受灾情况,及时做好灾害预警及减灾措施。

Local and regional flood frequency analysis based on hierarchical Bayesian model in Dongting Lake Basin,China

This study developed a hierarchical Bayesian(HB)model for local and regional flood frequency analysis in the Dongting Lake Basin,in China.The annual maximum daily flows from 15 streamflow-gauged sites in the study area were analyzed with the HB model.The generalized extreme value(GEV)distribution was selected as the extreme flood distribution,and the GEV distribution location and scale parameters were spatially modeled through a regression approach with the drainage area as a covariate.The Markov chain Monte Carlo(MCMC)method with Gibbs sampling was employed to calculate the posterior distribution in the HB model.The results showed that the proposed HB model provided satisfactory Bayesian credible intervals for flood quantiles,while the traditional delta method could not provide reliable uncertainty estimations for large flood quantiles,due to the fact that the lower confidence bounds tended to decrease as the return periods increased.Furthermore,the HB model for regional analysis allowed for a reduction in the value of some restrictive assumptions in the traditional index flood method,such as the homogeneity region assumption and the scale invariance assumption.The HB model can also provide an uncertainty band of flood quantile prediction at a poorly gauged or ungauged site,but the index flood method with L-moments does not demonstrate this uncertainty directly.Therefore,the HB model is an effective method of implementing the flexible local and regional frequency analysis scheme,and of quantifying the associated predictive uncertainty.