flood

摘要： In watershed hydrology,the morphometric features of a river basin are vital to examine the lower Orashi River basin morphological and hydrological aspects,as well as its flood potential,based on their morphometric characteristics using remotely sensed SRTM data that was analyzed with ArcGIS software.The areal,linear,and relief aspects of the Orashi River basin were examined as morphometric parameters.The lower Orashi river basin,according to the findings,has a total size of 625.61 km2 and a perimeter of 307.98 km,with a 5th order river network based on Strahler categorization and a dendritic drainage pattern.Because of low drainage density,the drainage texture is very fine,the relief is low,and the slope is very low.Bifurcation ratio,circularity ratio,drainage density aspect ratio,form factor,and stream frequency values indicate that the basin is less elongated and would produce surface runoff for a longer period,while topographic changes show that the river is decreasing with depth in the land area at about the same elevation as a result of sand deposited due to lack of maintenance by dredging,which implies that the basin is morphometrically elevated and sensitive to erosion and flooding.To understand geo-hydrological features and to plan and manage watersheds,morphometric analysis based on geographic information systems and remote sensing techniques is beneficial.

摘要： The GM(1,1)grey model was used to simulate and divide the harvest years of black-skinned sugarcane yield in Wengyuan County during 2006-2021.Based on the meteorological observation data of Wengyuan County during the same period,the impact of major meteorological disasters such as drought,flood and frost in the growth period of black-skinned sugarcane was analyzed.It is believed that the instability of black-skinned sugarcane yield was affected by comprehensive meteorological factors.It is necessary to master the characteristics of local meteorological disasters,conduct scientific cultivation according to local conditions,and continuously improve the meteorological service level of black-skinned sugarcane cultivation.

摘要： Is GI(Green Infrastructure)viable to mitigate urban pluvial flood caused by extreme storm events?Limited research and planning have been undertaken in recent years,but little practice has been found in the real world.This retrospective study provides an example of mitigating pluvial flood by LID(Low Impact Development)principal and practices and transforming an old,ultra-dense low-income community into a climate change resilient community.The key findings include keeping flood control in mind when designing GI in the beginning;mimicking the sites’hydrologic characteristics as much as possible;outreaching to residences for maintenance issues from the beginning and monitoring the performance of GI facilities continuously.Technically,bioretention growing media with higher infiltration rate is specified that must be great than 150 mm/h in short term and 80 mm/h for long term;this paper chose low maintenance permeable pavement products avoiding clogging;and increasing parking space without compromising the design goals.

摘要： The year of 2021 has witnessed many extreme weather events across the world that have shocked and challenged human society,in particular for the populous cities,challenging progress on sustainable city development.In the comment we highlighted the record-breaking rainstorm that is considered to happen only“once-in-a-thousand-years”on 20 July 2021 in Zhengzhou,China;and a series of short and long-term resilience enhancement and risk reducing measures to climate change and natural hazard risks.We found that increasing frequency and intensity of extreme weather events caused by human-induced climate change challenges progress on sustainable city development,but could also accelerate activities to enable cities to become more resilient.This comment is essential to advance towards the sustainable city development goal(SDG 11)in China’s mega cities,as well as informing progress for other global cities.

摘要： This paper reviews the significant contribution of hydrologic continuity in the development, evolution and fate of the Niger Delta. Formed from the aggregation of sediments from a drainage catchment area of over 2 million km2, the Niger Delta has evolved into a prolific sedimentary basin with a dense network of rivers and creeks. The ecological system is in a fragile state with fresh and saline water ecosystems maintaining a dynamic equilibrium. Rainfall typically varies from 2500 - 4000 mm per year compared to average annual evaporation of about 1500 mm, resulting in net antecedent moisture. Over 70% of the rainfall occurs in 4 months between May and September, creating a potential for flooding. Water level varies from less than 1.5 m in the estuaries to about 8 m at the apex of the delta, with Nun River having a slightly higher elevation compared to Forcados River, implying that canals connecting both rivers at the same reach would experience water movements from Nun to Forcados River. Similarly, water level gradients vary across the stretch of the rivers from 8.6 to 9.5 × 10-5 (cm/km) between Onitsha and Asamabiri, 7.5 to 7.7 × 10-5 (cm/km) on the Forcados River downstream of Asamabiri, and from 7.4 to 7.6 × 10-5 (cm/km) on the Nun River. At peak flood, about 23 × 103 m3/sec of runoff enters the Niger Delta. At the same time, about 16 × 103 m3/sec discharges from the estuaries into the ocean in a semi-diurnal tidal flow leaving a surplus that accumulates to cause flooding. The delta thus acts like a sponge, absorbing the shear amount of flow and releasing slowly stored water through at least twenty-one outlet estuaries into the Atlantic Ocean. The shear amount of discharge overwhelms the capacity of the network of distributaries and predisposes the delta to flooding. Assessment of the capacity of the rivers to evacuate pollutants showed that rivers to the west of Brass which are fed by Forcados River exhibited relatively stronger flux efficiencies prior to 1998 but are presently weaker compared to rivers fed by Nun. The rivers to the east between New Calabar and Imo Rivers exhibited very weak ebb tide asymmetry or net upstream flow largely because these rivers receive little or no freshwater influx from upstream sources. Flood and erosion are the major hydrological hazards in the region.

摘要： Mexico is one of the major textile and garment trading countries in the world.The textile and garment industry is its traditional advantageous industry and plays an important role in Mexico’s national economy.Mexico textile and garment industry products are relatively complete,including all kinds of yarns,fabrics,home textiles,nonwovens and all kinds of clothing.

摘要： Dam construction industry has concerned specific attention to engineering economy,over the past years;so in this direction the topic of emergency fusegates has considered as a new technology since 1989,in all over the world.Fusegate is a simple,safe,and robust structure in increasing live storage or spillway capacity and a mechanical equivalent of a fuse plug.Although the installation of gates with different types and heights might practically be difficult,but its lower annual cost,flexibility in operation and smaller wasted water resulting from gates tipping justifies their selection as a more desirable solution.In this paper,the fusegates of Sarough storage dam(Googerdchi)in West-Azerbaijan province is studied an analyzed.The fusegates are installed for the first time in Iran,on Sarough dam spillway instead of radial gates.By installing these gates,the storage capacity of the reservoir increased up to gates overhead level for about 10 mcm.Flood hydrograph in six different return periods(from 2 to 1000 years)of the dam,shows that dam capacity has increased by equipping with fusegates.In addition,a comparison discharge-time-reservoir level chart between 1st to 6th individual fusegate overthrow periods is done.

摘要： The aim of this study was to highlight the effect of tide on the variation of the physicochemical parameter in the Kienké estuary. Six (06) environmental variables were monitored at nine (09) stations with the time step of one hour from 7 am to 7 pm on 4th August 2019. The hovmuller analysis showed that salinity, conductivity, total dissolved solids, and pH values increased during the flood phase and decreased during the ebb phase while oxygen concentration decreased during the flood and increased during the ebb phase. The stratification parameter has shown that the influx of seawater during high tide shifts the Kienké estuary from a well-mixed to a partially mixed environment.

摘要： The"corridor"constructed jointly by multi-nationalities provides a space of cultural dissemination for the Legend of King Yu Tamed the Flood the in Hexi Corridor.Legend of King Yu Tamed the Flood spreads on the flowing cultural"corridor",relying on various narrative forms of cultural media.It deeply promotes the localization of the Legend of King Yu Tamed the Flood.The situation of integration and harmony between ethnic groups and Common value orientation of multi-ethnic humanities and religions are explored and taken through the multicultural elements embedded in the legend so that the"cultural integration"hidden in the legends and stories can emerge.

摘要： The Yellow River Basin is one of the important sand-producing and sediment-transporting areas in China,and one of the three most important sand-producing areas in the world.The amount of sand and dust days in the“Three Norths”(Dongbei,Xibei,and Huabei)area has increased,and regional sand and dust storms have occurred frequently.There are generally more serious hidden danger points of debris flow geological disasters in small and medium-sized river basins.The technical achievements of flood risk forecasting and early warning for medium and small rivers in the Yellow River Basin based on rainstorm-induced floods are important technical supports for flood forecasting and early warning for medium and small rivers.Based on this,a case study was carried out on the problems such as the weak forecasting and early warning ability of flood disasters induced by heavy rain and the low accuracy of flood disaster loss assessment in the flood disasters of medium and small rivers,for the reference of relevant personnel.

摘要： 本发明公开了一种ACK Flood攻击的防护方法及装置，用以解决在不断开客户端和服务器之间的连接的前提下，提高识别非法客户端的精确度的问题。该方法包括：中间防护设备针对拦截的每一客户端发送的ACK报文，基于在客户端发送ACK报文之前中间防护设备返回给客户端的ACK响应报文中的一段报文段，生成探测报文；丢弃ACK报文，将探测报文返回客户端；当确定客户端返回探测响应报文时，检测其中是否包含SACK选项；如果是，则根据SACK信息判定客户端是否为合法客户端；当确定客户端为合法客户端时，将客户端重传的ACK报文发送至相应的目标服务器；否则，将重传的ACK报文丢弃；如果否，则将客户端重传的ACK报文丢弃。

摘要： 本发明公开了一种针对HTTP Flood攻击的检测方法、装置、设备及介质，用以解决现有技术中对当前网络流量中是否存在HTTP Flood攻击检测不够准确的问题。由于本发明实施例可以在判断第一网络流量不位于当前保存的流量阈值范围内时，可以对该第一流量阈值进行更新，并基于更新后的第一流量阈值，检测下一相邻设定时长的第二网络流量是否存在HTTP Flood攻击，本发明实施例中当前保存的第一流量阈值可以随着当前网络流量的改变而自适应的进行调整，相比现有采用固定不变的第一流量阈值，可以提高检测当前网络流量中是否存在HTTP Flood攻击的准确性。

摘要： 本发明的实施例提供了一种SYN Flood攻击清洗方法、装置、电子设备和可读存储介质，涉及安全技术领域。本发明实施例提供的SYN Flood攻击清洗方法、装置、电子设备和可读存储介质，在接收目标SYN报文后，通过提取目标SYN报文中的参数信息，根据参数信息查找是否存在相同参数信息的目标历史缓存表项，若存在目标历史缓存表项，根据接收到目标SYN报文的报文时间、目标历史缓存表项中的时间戳和第一时间差值，对目标SYN报文进行验证。如此，根据SYN报文的时延对SYN报文进行合法性验证，可有效识别出非法的SYN报文，并进行清洗，且准确性较高。

摘要： 本发明公开了一种针对传统DDOS防火墙SYN FLOOD防护在工业网络中的改进方法。本发明针对传统DDOS防火墙SYN FLOOD防护在工业网络中的改进方法，包括：步骤一：捕获以太网络中的数据包；步骤二：解析TCP协议SYN报文，针对目的IP地址进行数量统计；步骤三：根据预设值的阈值与SYN报文统计数比对，如果统计数未超过阈值，则进入步骤四，如果超过阈值则进入步骤八。本发明的有益效果：本专利针对未超过阈值部分SYN FLood攻击流量进行主动释放处理，减少被攻击目标内存占用时间，使被攻击目标较快速的恢复到未遭受攻击时的正常工作状态，从而对工业设备达到安全防护的效果。

摘要： 本申请提供一种基于用户行为检测HTTP FLOOD攻击的方法和装置，该方法中，检测装置通过解析HTTP报文，获取HTTP报文中包含的来源特征信息以及目的特征信息，并生成特征信息列表；根据特征信息列表，统计主机访问目标网站的异常行为分数；若主机的异常行为分数大于第一阈值，比较主机在固定时间段内发送HTTP报文的频率与第二阈值；若主机在固定时间段内发送HTTP报文的频率大于第二阈值，确定主机向目标网站的服务器发出HTTP FLOOD攻击。本申请通过主机行为异常情况结合频率统计判断主机是否发出HTTP FLOOD攻击，在第二阈值设置的比较小的情况下，不仅能够避免现有技术中正常主机被误认为发出HTTP FLOOD攻击的情况，同时能够检测到DDoS，提高HTTP FLOOD攻击检测的精度。

摘要： 本发明公开了一种SYN Flooding网络攻击场景复现方法，具体按照以下步骤实施：步骤1、选择网络攻击样本；步骤2、进行网络场景搭建；设置网络攻击复现参数；在攻击中抓取相应的pcap数据包，并对该数据包使进行数据处理，得到复现所生成的双向流量特征；步骤5、对步骤1得到攻击样本所生成的双向流量特征与步骤2得到的复现所生成的双向流量特征进行比较，如果存在差别，回到步骤3，重新调整攻击参数，直至步骤1得到攻击样本所生成的双向流量特征与步骤2得到的复现所生成的双向流量特征相同。解决了现有技术中存在的攻击场景复现还存在传统网络环境搭建不够灵活、依赖物理基础设施来建立连接并正常运行的问题。

摘要： 本申请提供一种针对SYNFlood攻击的检测与防御方法，步骤包括：S1，攻击检测步骤：对系统进行SYNFlood攻击监控，判断当前系统是否正在被攻击，若判断为是，转入步骤S2；S2，攻击防御步骤：对系统接收到的报文进行TCP源检测，判断报文的IP是否为合法IP；若判断为是，则将IP加入白名单；若判断为否，则丢弃报文。本申请能够在不增加网络与主机负载的前提下，高效准确的对SYN Flood攻击进行防御。

摘要： 本发明公开了基于计数型布隆过滤器的SYN Flood攻击检测方法，包括检测某段时间内单个源IP的TCP连接请求包个数，并取其最大值作为阈值，或者手动设置一个阈值；构建一个计数表、一个白名单和黑名单，并初始化；在当前时间周期内检测的TCP报文的接收；获取接收的TCP报文的源目IP，并用k个独立的哈希函数对源目IP进行运算，得到k个哈希值，并寻找k个哈希值在计数表中的对应位置；判断接收的TCP报文是否在黑名单或白名单或阈值范围内，并对相应判断结果做出TCP报文丢弃或通过的选择。本发明占用内存小且匹配速度快，能够实现对SYN Flood攻击的防御；通过选取合适的哈希函数个数和数组长度，以及定时重置数组中的数据，减少误报率。

摘要： 本发明公开了一种ACK Flood攻击的防护方法及装置，用以解决在不断开客户端和服务器之间的连接的前提下，提高识别非法客户端的精确度的问题。该方法包括：中间防护设备针对拦截的每一客户端发送的ACK报文，基于在客户端发送ACK报文之前中间防护设备返回给客户端的ACK响应报文中的一段报文段，生成探测报文；丢弃ACK报文，将探测报文返回客户端；当确定客户端返回探测响应报文时，检测其中是否包含SACK选项；如果是，则根据SACK信息判定客户端是否为合法客户端；当确定客户端为合法客户端时，将客户端重传的ACK报文发送至相应的目标服务器；否则，将重传的ACK报文丢弃；如果否，则将客户端重传的ACK报文丢弃。

摘要： 本发明公开了一种多核异构平台下SYN Flood攻击防御方法，采用基于源IP地址的白名单及红黑名单的方式进行攻击防御，防御过程中没有建立会话表而产生的内存资源开销，在防御攻击的同时，仍然能保证正常流量的畅通。