Urban flooding in Chittagong City usually occurs during the monsoon season and a rainwater harvesting(RWH)system can be used as a remedial measure.This study examines the feasibility of rain barrel RWH system at a dis...Urban flooding in Chittagong City usually occurs during the monsoon season and a rainwater harvesting(RWH)system can be used as a remedial measure.This study examines the feasibility of rain barrel RWH system at a distributed scale within an urbanized area located in the northwestern part of Chittagong City that experiences flash flooding on a regular basis.For flood modeling,the storm water management model(SWMM)was employed with rain barrel low-impact development(LID)as a flood reduction measure.The Hydrologic Engineering Center's River Analysis System(HEC-RAS)inundation model was coupled with SWMM to observe the detailed and spatial extent of flood reduction.Compared to SWMM simulated floods,the simulated inundation depth using remote sensing data and the HEC-RAS showed a reasonable match,i.e.,the correlation coefficients were found to be 0.70 and 0.98,respectively.Finally,using LID,i.e.,RWH,a reduction of 28.66%could be achieved for reducing flood extent.Moreover,the study showed that 10%e60%imperviousness of the subcatchment area can yield a monthly RWH potential of 0.04e0.45 m3 from a square meter of rooftop area.The model can be used for necessary decision making for flood reduction and to establish a distributed RWH system in the study area.展开更多
Rice(Oryza sativa)plants acquired excess photosynthates in the form of nonstructural carbohydrates(NSCs)in their stems and grain.Despite keen interest in rice NSC,the dynamics of NSC accumulation,translocation and re-...Rice(Oryza sativa)plants acquired excess photosynthates in the form of nonstructural carbohydrates(NSCs)in their stems and grain.Despite keen interest in rice NSC,the dynamics of NSC accumulation,translocation and re-accumulation have not yet been well investigated.AG1 and AG2 QTLs associated with flooding tolerance through catalyzing starch into soluble sugar in germinating seeds.Here we conducted three experiments,greenhouse and field to lay the groundwork for large-scale diversity studies on grain NSC and some agronomic traits under direct-seeded rice(DSR)system,using elite lines incorporating AG1,AG2 and AG1-AG2 QTLs into the popular varieties PSB Rc82 and Ciherang-Sub1 along with the donors Kho Hlan On(AG1)and Ma-Zhan Red(AG2).In germinating seedlings,soluble sugars increased,while starch concentration decreased gradually especially in the tolerant checks and AG1-AG2 introgression lines under flooded soil.Soluble sugar accumulation in stem started to increase from the vegetative stage and peaked at the panicle initiation stage then gradually decreased towards the maturity stage.But Sub1-AG lines had higher sugar and starch concentrations at different growth stages than other genotypes in wet season 2016 and dry season 2017.Plant survival rate was positively correlated with the stem NSC at the early vegetative stage(21 days after sowing),and stem NSC was positively associated with plant height at different growth stages.Among the tested seeding rate,the most suitable seeding rate,4 g/m2 with shallow burial depth(0.5 cm),resulted in better seedling establishment,relatively higher seedling vigor index and higher leaf area index under flooding in DSR system.Introgression of AG1-AG2 QTLs had no any negative impact on nonstructural carbohydrate,germination rate,and growth and biomass production.展开更多
Taking Dongting Lake district as the studying area and utilizing multi-temporal MOS-lb/MESSR data as remote sensing info source, by the combination operation and ratio transform processing and the image, spectrum and ...Taking Dongting Lake district as the studying area and utilizing multi-temporal MOS-lb/MESSR data as remote sensing info source, by the combination operation and ratio transform processing and the image, spectrum and histogram comparison of the MESSR image data of all bands for the flood season and dry season with the ER-DAS IMAGINE system, a classification model was established, which can be used to acquire the spatial distributing information of water bodies. Meanwhile a water depth index model was derived and built, and then a model for detecting the depth of water body based on the non-linear recursive analysis was presented. By the overlay analysis of the classification thematic images based on the model for extracting flood information, the flooding area and distributing information were acquired.展开更多
针对传统城市内涝风险评估方法存在较强主观性问题,将地理信息系统技术与云化信息扩散(Cloud-based Information Diffusion,CID)模型相结合,提出了一种网格化城市内涝风险积水深度CID计算模型。将郑州市中原区、二七区、金水区和管城回...针对传统城市内涝风险评估方法存在较强主观性问题,将地理信息系统技术与云化信息扩散(Cloud-based Information Diffusion,CID)模型相结合,提出了一种网格化城市内涝风险积水深度CID计算模型。将郑州市中原区、二七区、金水区和管城回族区交界处街区作为研究区,对研究区2013—2021年气象站点逐小时降雨数据进行统计分析,提取24 h累计连续降雨量超40 mm的27场典型降雨过程作为降水过程样本,利用基于暴雨管理模型二次开发的城市雨洪模型构建研究区城市内涝模拟模型,对模拟模型进行参数率定、模型精确性验证后,通过选定的27场降水过程数据模拟形成研究区27幅百米网格内涝分布图,形成网格化最大雨强-最大积水深度二维数据集;在二维正态信息扩散模型中引入云化信息模型的期望E_(x)、熵E_(n)和超熵H_(e)指标,形成二维云化信息扩散模型;建立信息扩散模型知识表达系统,并用于表达信息扩散模型的信息量分配关系,实现网格单元风险积水深度的预测计算。研究区进行格网剖分后,共形成了5760个网格,以100 mm/h雨强为降水场景示例,计算研究区所有网格单元在示例降水条件下的风险积水深度预测值,形成区域内涝预报图。研究结果显示,该方法能够显著降低灾害样本信息中的模糊性和随机性,有效实现网格化内涝风险积水深度预测,有助于提高内涝防灾减灾技术能力。展开更多
基金supported by a fund on a day-to-day basis provided by the Department of Civil Engineering,Chittagong University of Engineering&Technology(CUET),Bangladesh.
文摘Urban flooding in Chittagong City usually occurs during the monsoon season and a rainwater harvesting(RWH)system can be used as a remedial measure.This study examines the feasibility of rain barrel RWH system at a distributed scale within an urbanized area located in the northwestern part of Chittagong City that experiences flash flooding on a regular basis.For flood modeling,the storm water management model(SWMM)was employed with rain barrel low-impact development(LID)as a flood reduction measure.The Hydrologic Engineering Center's River Analysis System(HEC-RAS)inundation model was coupled with SWMM to observe the detailed and spatial extent of flood reduction.Compared to SWMM simulated floods,the simulated inundation depth using remote sensing data and the HEC-RAS showed a reasonable match,i.e.,the correlation coefficients were found to be 0.70 and 0.98,respectively.Finally,using LID,i.e.,RWH,a reduction of 28.66%could be achieved for reducing flood extent.Moreover,the study showed that 10%e60%imperviousness of the subcatchment area can yield a monthly RWH potential of 0.04e0.45 m3 from a square meter of rooftop area.The model can be used for necessary decision making for flood reduction and to establish a distributed RWH system in the study area.
基金This study was supported by the Lee Foundation Scholarship(PhD)through International Rice Research Institute,the PhilippinesThe authors are thankful to Melencio J.APOSTOL for his technical assistance,and to Frederickson ENTILA and Evangelina S.ELLA for helpful suggestions and comments during this study.
文摘Rice(Oryza sativa)plants acquired excess photosynthates in the form of nonstructural carbohydrates(NSCs)in their stems and grain.Despite keen interest in rice NSC,the dynamics of NSC accumulation,translocation and re-accumulation have not yet been well investigated.AG1 and AG2 QTLs associated with flooding tolerance through catalyzing starch into soluble sugar in germinating seeds.Here we conducted three experiments,greenhouse and field to lay the groundwork for large-scale diversity studies on grain NSC and some agronomic traits under direct-seeded rice(DSR)system,using elite lines incorporating AG1,AG2 and AG1-AG2 QTLs into the popular varieties PSB Rc82 and Ciherang-Sub1 along with the donors Kho Hlan On(AG1)and Ma-Zhan Red(AG2).In germinating seedlings,soluble sugars increased,while starch concentration decreased gradually especially in the tolerant checks and AG1-AG2 introgression lines under flooded soil.Soluble sugar accumulation in stem started to increase from the vegetative stage and peaked at the panicle initiation stage then gradually decreased towards the maturity stage.But Sub1-AG lines had higher sugar and starch concentrations at different growth stages than other genotypes in wet season 2016 and dry season 2017.Plant survival rate was positively correlated with the stem NSC at the early vegetative stage(21 days after sowing),and stem NSC was positively associated with plant height at different growth stages.Among the tested seeding rate,the most suitable seeding rate,4 g/m2 with shallow burial depth(0.5 cm),resulted in better seedling establishment,relatively higher seedling vigor index and higher leaf area index under flooding in DSR system.Introgression of AG1-AG2 QTLs had no any negative impact on nonstructural carbohydrate,germination rate,and growth and biomass production.
文摘Taking Dongting Lake district as the studying area and utilizing multi-temporal MOS-lb/MESSR data as remote sensing info source, by the combination operation and ratio transform processing and the image, spectrum and histogram comparison of the MESSR image data of all bands for the flood season and dry season with the ER-DAS IMAGINE system, a classification model was established, which can be used to acquire the spatial distributing information of water bodies. Meanwhile a water depth index model was derived and built, and then a model for detecting the depth of water body based on the non-linear recursive analysis was presented. By the overlay analysis of the classification thematic images based on the model for extracting flood information, the flooding area and distributing information were acquired.
