地表径流速度对城市内涝影响规律

为分析地表径流速度对城市内涝的影响,采用一维地下排水管网与二维城区地形的动态耦合模型,选取大连市某排水区块作为研究区域,设置4种地表径流速度10种设计降雨场景,模拟分析在不同重现期设计降雨及不同地表径流速度下研究区的内涝积水特性。结果表明:随着地表径流速度降低,管道排水压力变小,管道排水达标率最高可提升48.05%,且降雨重现期越短,地表径流流速对管道排水压力的削减效果越明显;地表径流流速对检查井溢流量影响显著,随着地表径流速度降低,检查井溢流量峰值最高可减小2 750 m~3,峰现时间最长可滞后56 min,同时随着降雨重现期增长,地表径流流速对检查井溢流量的削减效果减弱;研究区低、高风险区淹没面积随地表径流速度降低,最高可分别减小1.64万、8.37万m~2,但中风险区淹没面积变化反复。     

基于分形理论的黄河内蒙古段河势演变特征及其与凌汛灾害关联研究

寒区河道凌汛灾害河势“弯道效应”的量化评估十分重要。基于分形理论提出河道横断面-纵剖面-平面多维度河势分形维数计算方法及其物理机制，并探讨黄河内蒙古段不同维度河势演变分形特征及其与凌汛灾害的关联关系。结果表明，黄河内蒙古段不同维度河势均具有多尺度自相似分形特征，且具有多年记忆周期的长程相关性；冰坝（严重性冰塞）发生频次与河道主槽弯曲分形维数呈正相关指数型函数关系，与河相系数、深泓点高程和河段平均底坡分形维数负相关，与水深-面积分形维数正相关，总体表明冰坝灾害更易发生于主槽偏移摆动大、蜿蜒曲折、河湾发育程度高的宽浅型弯曲河道，研究成果可为凌汛期冰塞冰坝灾害易发河段诊断及预测提供重要理论依据。     

Laboratory Studies to Determine Suitable Chemicals to Improve Oil Recovery from Garzan Oil Field

Garzan oil field is located at the south east of Turkey. It is a mature oil field and the reservoir is fractured carbonate reservoir. After producing about 1% original oil in place (OOIP) reservoir pressure started to decline. Waterflooding was started in order to support reservoir pressure and also to enhance oil production in 1960. Waterflooding improved the oil recovery but after years of flooding water breakthrough at the production wells was observed. This increased the water/oil ratio at the production wells. In order to enhance oil recovery again different techniques were investigated. Chemical enhanced oil recovery (EOR) methods are gaining attention all over the world for oil recovery. Surfactant injection is an effective way for interfacial tension (IFT) reduction and wettability reversal. In this study, 31 different types of chemicals were studied to specify the effects on oil production. This paper presents solubility of surfactants in brine, IFT and contact angle measurements, imbibition tests, and lastly core flooding experiments. Most of the chemicals were incompatible with Garzan formation water, which has high divalent ion concentration. In this case, the usage of 2-propanol as co-surfactant yielded successful results for stability of the selected chemical solutions. The results of the wettability test indicated that both tested cationic and anionic surfactants altered the wettability of the carbonate rock from oil-wet to intermediate-wet. The maximum oil recovery by imbibition test was reached when core was exposed 1-ethly ionic liquid after imbibition in formation water. Also, after core flooding test, it is concluded that considerable amount of oil can be recovered from Garzan reservoir by waterflooding alone if adverse effects of natural fractures could be eliminated.     

Cross-sector collaboration within Dutch flood risk governance: historical analysis of external triggers

ABSTRACT

This article synthesizes the literature on Dutch flood risk governance to analyze how external conditions shaped past and present dynamics of cross-sector collaboration for integrated flood risk management in the Netherlands. It traces the extent to which policy and legal frameworks, socio-economic circumstances, political realities, power relations and conflict situations have influenced attempts at collaboration between flood safety, spatial planning, environmental protection and other sectors. Despite the growing interdependences, existing power relations between the sectors are characterized by the dominance of the water sector. Hence, cross-sector collaboration can develop as long as it does not compromise flood safety.     

淮河入江水道行洪能力分析

入江水道是淮河下游最大的泄洪河道,承担着淮河上中游70%以上的洪水泄入长江。根据1961—2018年大洪水期间的实测资料,利用水位流量法计算分析入江水道的泄洪能力和防洪能力。结果表明:因历史客观条件限制以及4个梯级控制河段整治的难度与复杂性,在不同时期各控制河段的行洪能力呈现各自不同的特点;经过多年持续有效治理,河道行洪能力整体得到提高;由近年来实测资料推算,各控制河段的行洪能力基本达到设计要求。对入江水道行洪能力的分析为淮河下游区的防汛抗洪和降低特大洪水威胁提供借鉴和参考,对区域经济社会又好又快发展具有现实意义。     

平原地区城市湖泊防洪与景观功能协调研究——以枝江市金湖为例

为了使城市湖泊尽可能滞蓄雨洪、发挥景观功能、打造良好的居民"亲水空间",以枝江市金湖为例,根据金湖主要泄洪渠道的实际情况,利用Mike 21模型模拟计算汛限水位值,按照景观水位确定大、小洪水工况下合理的水位。在此基础上,提出传统的静态景观水位与改进的动态景观水位两种方案。结果表明:以50年一遇、30年一遇为代表的大洪水工况下合理景观水位为40.7 m,以20年一遇、10年一遇为代表的小洪水工况合理景观水位为41.3 m;静态方案采用50年一遇洪水计算结果为标准执行,将40.7 m作为金湖固定的景观水位;动态方案水位可在41.3~40.7 m之间波动;金湖适宜采用动态景观水位运行方案,水位可在40.7~41.3 m之间波动;根据短期预报及历史监测资料分析后合理调度,将41.3 m作为金湖常水位,确定预测洪水大小后调整水位迎战洪水。据此,可在充分利用水资源的同时有效协调景观高水位需求与防洪之间的矛盾。     

Cloud asset for urban flood control

The performance of physical assets has become a major determinant success factor for urban flood control. However, managing these assets is always challenging as there are a huge number of diverse assets involved, which are distributed throughout the city, and owned by different agencies. Aiming at improving the management efficiency of these assets, and ensuring their performance, this paper proposes the concept of cloud asset based on cloud computing, mobile agent, and various smart devices. Through hardware integration and software encapsulation, cloud asset could sense its real-time status, adapt to varied working scenarios, be controlled remotely, and shared among agencies. It enables accurate real-time control of every asset, and thus improves the management efficiency and effectiveness. This paper first presents the concept of cloud asset with its technical architecture, and then analyses the software agent model for cloud asset, which is the key enabler to realize UPnP (Universal Plug and Play) management of assets, and provides mobility and intelligence for them. After that, the framework of cloud asset-enabled workflow management is built, in which cloud asset could be easily found and dynamically invoked by different workflows. Finally, a demonstrative case is provided to verify the effectiveness of cloud asset.     

Adaptation to climate change and conservation of biodiversity using green infrastructure

In recent years, we have experienced mega‐flood disasters in Japan due to climate change. In the last century, we have been building disaster prevention infrastructure (artificial levees and dams, referred to as “grey infrastructure”) to protect human lives and assets from floods, but these hard protective measures will not function against mega‐floods. Moreover, in a drastically depopulating society such as that in Japan, farmland abandonment prevails, and it will be more difficult to maintain grey infrastructure with a limited tax income. In this study, we propose the introduction of green infrastructure (GI) as an adaptation strategy for climate change. If we can use abandoned farmlands as GI, they may function to reduce disaster risks and provide habitats for various organisms that are adapted to wetland environments. First, we present a conceptual framework for disaster prevention using a hybrid of GI and conventional grey infrastructure. In this combination, the fundamental GI, composed of forests and wetlands in the catchment (GI‐1) and additional multilevel GIs such as flood control basins that function when floodwater exceeds the planning level (GI‐2) are introduced. We evaluated the flood attenuation function (GI‐1) of the Kushiro Wetland using a hydrological model and developed a methodology for selecting suitable locations of GI‐2, considering flood risk, biodiversity and the distribution of abandoned farmlands, which represent social and economic costs. The results indicated that the Kushiro Wetland acts as a large natural reservoir that attenuates the hydrological peak discharge during floods and suitable locations for introducing GI‐2 are concentrated in floodplain areas developing in the downstream reaches of large rivers. Finally, we discussed the network structure of GI‐1 as a hub and GI‐2 as a dispersal site for conservation of the Red‐crowned Crane, one of the symbolic species of Japan.     

变化环境下由设计暴雨推求设计洪水方法研究

为推求变化环境下的设计洪水,以黄河上游唐乃亥站以上流域1967~2006年的年最大15d降雨量系列为例,基于设计暴雨与SWAT模型相结合的方法,首先构建变参数概率分布函数模型描述变化环境下非一致性暴雨极值系列的分布规律,随后基于等可靠度方法推求给定重现期条件下的设计暴雨值,再结合SWAT水文模型推求设计洪水。结果表明,变化环境下唐乃亥站以上流域各设计频率(P=10%、5%、2%、1%)的设计暴雨值随工程设计寿命(20、30、50、80、100年)的增大而减小,百年一遇设计洪峰从3 292m^3/s降至3 023m^3/s,洪量从29.9×10^8 m^3降至27.4×10^8 m^3。实例应用验证了该方法的可行性,可为变化环境下的设计洪水计算提供参考。     

一种改进的合成流量法及其在水文预报中的应用

合成流量法对下游站流量作出预报的关键是确定各上游站流量到达下游站的时间。在实际中常采用平均传播时间,然而不同水情下真实传播时间与平均传播时间存在一定的差距,影响预报精度。对此,提出时间窗口概念,以平均传播时间为中心,向前、后各开一个时间窗口,用上游各站时间窗口内流量的线性组合表示其到达下游站的流量,以提高模型对不同水情的适应能力和预报精度。以三峡水库2009~2015年流量数据率定参数,以2016~2018年流量数据作为预报对象,试验结果表明时间窗口法能够显著改善预报精度。