<p>High-resolution Quantitative Precipitation Forecasts (QPF) &... more <p>High-resolution Quantitative Precipitation Forecasts (QPF)  are essential to accurately forecast the magnitude, timing and location of precipitation and as input for pluvial flood forecasting using urban drainage models. However, there are challenges of producing high-resolution forecast capable of capturing the spatial and temporal variability of rainfall needed for urban flood modelling and the uncertainty associated with meteorological forecast and urban flood models. Therefore there is a challenge to balance data availability, model uncertainty, resolution, forecast lead-time and computational demands, especially in data-scarce regions.</p><p>Ensemble precipitation forecasts are used to capture uncertainties of meteorological forecasting in flood models. This research aims to evaluate the skill of a downscaled ensemble precipitation forecast over the coastal city of Alexandria, Egypt which experiences extreme rainfall and flooding from winter storms. A Weather Research Forecast (WRF) convection-permitting model was initialised using the Global Ensemble Forecast System (GEFS) which provides 21 ensemble members (1 degree archived). The model was run using three domains with horizontal grid resolutions of 30km, 10 km and 3.3 km at a 24h leadtime). For the 3.3 km horizontal grid, ensemble members were coupled with a 1D Mike urban model to evaluate the meteorological uncertainty representation and propagation.</p><p>In the absence of sufficient rainfall and flow gauge data, results were verified against Multi-Source Weighted-Ensemble Precipitation (MSWEP) satellite-derived product and further compared with the ECMWF ensemble prediction system precipitation forecast. 1D flood simulations were evaluated against 1D- 2D hydrodynamic simulations run with MSWEP data.</p><p>Ensembles showed varying probability of detection for different severity events. In general, the majority of ensemble rainfall values resulted in flooding greater than the flooding simulated from the satellite observed rainfall. Although deterministic forecast also indicated flooding and threshold exceedance, the number of ensemble members exceeding critical thresholds has the benefit of providing decision-makers with the probability of threshold exceedance and likelihood of flooding to trigger protective actions. A study such as this provides knowledge for understanding, future applications and limitations of using high-resolution ensemble Quantitative Precipitation Forecasts (QPFs) and the importance of capturing the spatial and temporal variability of rainfall in urban drainage models. Additionally, the potential use of MSWEP for the verification of ensemble forecasts in ungauged and data-scarce regions is investigated.</p>
Water Sensitive City is a term coined within urban water management representing the interaction ... more Water Sensitive City is a term coined within urban water management representing the interaction between different branches of water science and other domains such as urban planning and design in order to establish liveable cities. Flood resilience is the ability of a system to recover from disturbance and also to retain original functional identity in some form in the face of long-term change. Sustainable systems with respect to water management are mainly dominated by their resilience, which is intrinsic to water sensitive cities and includes social, economic and environmental as well as technical systems, and their interactions. Systems cannot be considered in isolation but as a part of wider aspects of water and urban services and utilities in resilient cities. The growing movement for water sensitive urban design (WSUD) provides inspiration for maximising the value and use of water in urban areas, but so far lacks proper consideration of flood resilience. Synergistic integration between the ongoing knowledge on WSUD with flood resilience framework, can lead to establishing of a new model for water sensitive cities which are flood resilient, dealing with urban flooding in wiser manner while optimising the use of all kind of available resources.
Risk-informed flood risk management requires a comprehensive and quantitative risk assessment, wh... more Risk-informed flood risk management requires a comprehensive and quantitative risk assessment, which often demands multiple (thousands of) river and flood model simulations. Performing such a large number of model simulations is a challenge, especially for large, complex river systems (e.g., Mekong) due to the associated computational and resource demands. This article presents an efficient probabilistic modeling approach that combines a simplified 1D hydrodynamic model for the entire Mekong Delta with a detailed 1D/2D coupled model and demonstrates its application at Can Tho city in the Mekong Delta. Probabilistic flood-hazard maps, ranging from 0.5 to 100 year return period events, are obtained for the urban center of Can Tho city under different future scenarios taking into account the impact of climate change forcing (river flow, sea-level rise, storm surge) and land subsidence. Results obtained under present conditions show that more than 12% of the study area is inundated by t...
Alexandria (Egypt), similar to many other Arab cities in the Middle East and North Africa, experi... more Alexandria (Egypt), similar to many other Arab cities in the Middle East and North Africa, experiences occasional heavy rainfall and consequent pluvial flooding. For example, the last flood in Alexandria in 2015 led to wide-spread flooding in the city and caused huge damage and distress. The Assessment Report (version 5) of the Inter-Governmental Panel on Climate Change (IPCC) and the climate change impact assessment study of the World Bank predict that the situation will be exacerbated in the future. In the present research we carried out an analysis of the 2015 flood in Alexandria and concluded that a heavy rainfall could have been forecasted days ahead of the flooding event. As a follow up of the analysis we recommended the development of an early warning system to improve the preparedness of the city. The early warning system is seen as a risk reduction measure that will allow buying time to carry out more elaborate studies on larger investments to bolster flood prevention. Befo...
This paper presents a case study of a new adaptive, multi-level governance approach that supporte... more This paper presents a case study of a new adaptive, multi-level governance approach that supported a transition in river basin management in the Netherlands. The floods of 1993 and 1995 in the Netherlands triggered a paradigm shift in flood management. The 2.3 billion Euro flood safety programme Room for the River (RftR) was launched to increase flood safety by giving the rivers more room instead of merely enforcing the defence systems. This programme has been studied as a major stepping stone in the transition to integrated flood risk management: integrating spatial planning and flood risk management; and stimulating multi-level and multi stakeholder decision making. This research studied the outcomes of RftR beyond its mere delivery and how these outcomes came about. It comprised: 55 qualitative interviews, a survey amongst professionals and politicians (151) and extensive document analysis. First results indicate impact on: practice through guidelines in various disciplines; policy and regulation for e.g.: land use in outer marches; dyke requirements; regulation on soil and water quality; and other policy domains; scientific models and methods; and capacity building of people; organisational and management processes; and the creation and connection of networks. This outcome was obtained by stimulating social learning, within a multi-level programme organisation. This made it possible to signal, escalate and address barriers and opportunities for transition at the appropriate scale level and subsequently disseminate the lessons. For scholars in transition management and adaptive management RftR provides an example of a large-scale programme that changes the regime from within at the meso level.
As a result of the fast growth of remote sensing and data assimilation technology, many global la... more As a result of the fast growth of remote sensing and data assimilation technology, many global land use land cover (LULC) and climate reanalysis data sets have been used to advance our understanding of climate and environmental change. This paper investigates the precipitation variations of the Yangtze Delta Megalopolis by using precipitation reanalysis data under conditions of dynamic urban sprawl. Compared with current precipitation characteristic analyses, which are often based on a limited number of ground rainfall stations, the approach followed in this study comprises a grid-based statistical method using large sets of samples with a uniform distribution and a same representative grid area. This novel approach of dynamic sampling is applied in this study to overcome the temporal and spatial inconsistency of stationary sampling. This approach allows to examine the impact of urbanization on regional precipitation characteristics. The Yangtze Delta Megalopolis (YDM) region, one o...
Monitoring organic pesticides in surface water using grab water sampling method is ineffective in... more Monitoring organic pesticides in surface water using grab water sampling method is ineffective in most cases due to pesticides’ irregular emission and low solubility in water. To address the problem in water sampling method, this study used passive samplers (PS) composed of silicon rubber sheets (SR) and speedisk (SD). SR and SD were used respectively to measure hydrophobic and hydrophilic organic pesticides. These were submerged in river water uninterruptedly for 34 days. Pesticides in PS were extracted and analysed by sensitive analytical instruments HPLC, GC-MS MS and LC-MS MS. Pesticide assessment were conducted in two river systems in Cagayan de Oro River Basin, Philippines where agricultural run-off are unintentionally and continuously disposed from medium to huge plantations. The samplers were able to measure 105 emerging organic pollutants of which, 56 were organic pesticides and 22 organochlorine pesticides (OCP). Out of 56 pesticides, 11 were measured beyond the applied th...
Arbuscular mycorrhizal fungi (AMF) and its symbiosis with Canna indica on nitrogen (N) absorption... more Arbuscular mycorrhizal fungi (AMF) and its symbiosis with Canna indica on nitrogen (N) absorption was investigated for the remediation of contaminated soil. Canna indica plants with rhizome and leaf integrity intact were collected in spring and autumn seasons. To maintain the ideal nutrient composition, Hoagland concentrated nutrient solution was diluted with deionized water and additional nutrient solution was added periodically. Treated root samples were observed with an optical microscope and the number of hyphae and intersections as well as inoculation status were examined. High-throughput sequencing experiment was conducted to quantify AMF inoculation. Alpha diversity study was used to characterize abundance and diversity of the symbiosis. Hydroponic experiments were conducted to explore the absorption effectiveness of AMF-Canna symbiosis under different NH4+-N and NO3--N combinations. Hyphal colonization rate was only about 5.66 ± 1.08% in seedling stage in spring, but enhanced in the adult stage in autumn (53.89 ± 1.43%). Results revealed that AMF had no significant impact on NO3--N absorption by Canna roots, however, absorption of NH4+-N was improved by 63% under low concentration. Results revealed that when NH4+-N and NO3--N were applied combinedly in a 1:1 ratio, their respective absorption rates were enhanced to 99.63% and 99.50%. Compared with the case of NH4+-N as N source alone, synergistic effect of NH4+-N and NO3--N significantly changed the absorption of NH4+-N by C. indica, but its correlation with AMF inoculation was still not significant. Current findings could enhance understanding for effective N uptake and resource recovery.
<p>High-resolution Quantitative Precipitation Forecasts (QPF) &... more <p>High-resolution Quantitative Precipitation Forecasts (QPF)  are essential to accurately forecast the magnitude, timing and location of precipitation and as input for pluvial flood forecasting using urban drainage models. However, there are challenges of producing high-resolution forecast capable of capturing the spatial and temporal variability of rainfall needed for urban flood modelling and the uncertainty associated with meteorological forecast and urban flood models. Therefore there is a challenge to balance data availability, model uncertainty, resolution, forecast lead-time and computational demands, especially in data-scarce regions.</p><p>Ensemble precipitation forecasts are used to capture uncertainties of meteorological forecasting in flood models. This research aims to evaluate the skill of a downscaled ensemble precipitation forecast over the coastal city of Alexandria, Egypt which experiences extreme rainfall and flooding from winter storms. A Weather Research Forecast (WRF) convection-permitting model was initialised using the Global Ensemble Forecast System (GEFS) which provides 21 ensemble members (1 degree archived). The model was run using three domains with horizontal grid resolutions of 30km, 10 km and 3.3 km at a 24h leadtime). For the 3.3 km horizontal grid, ensemble members were coupled with a 1D Mike urban model to evaluate the meteorological uncertainty representation and propagation.</p><p>In the absence of sufficient rainfall and flow gauge data, results were verified against Multi-Source Weighted-Ensemble Precipitation (MSWEP) satellite-derived product and further compared with the ECMWF ensemble prediction system precipitation forecast. 1D flood simulations were evaluated against 1D- 2D hydrodynamic simulations run with MSWEP data.</p><p>Ensembles showed varying probability of detection for different severity events. In general, the majority of ensemble rainfall values resulted in flooding greater than the flooding simulated from the satellite observed rainfall. Although deterministic forecast also indicated flooding and threshold exceedance, the number of ensemble members exceeding critical thresholds has the benefit of providing decision-makers with the probability of threshold exceedance and likelihood of flooding to trigger protective actions. A study such as this provides knowledge for understanding, future applications and limitations of using high-resolution ensemble Quantitative Precipitation Forecasts (QPFs) and the importance of capturing the spatial and temporal variability of rainfall in urban drainage models. Additionally, the potential use of MSWEP for the verification of ensemble forecasts in ungauged and data-scarce regions is investigated.</p>
Water Sensitive City is a term coined within urban water management representing the interaction ... more Water Sensitive City is a term coined within urban water management representing the interaction between different branches of water science and other domains such as urban planning and design in order to establish liveable cities. Flood resilience is the ability of a system to recover from disturbance and also to retain original functional identity in some form in the face of long-term change. Sustainable systems with respect to water management are mainly dominated by their resilience, which is intrinsic to water sensitive cities and includes social, economic and environmental as well as technical systems, and their interactions. Systems cannot be considered in isolation but as a part of wider aspects of water and urban services and utilities in resilient cities. The growing movement for water sensitive urban design (WSUD) provides inspiration for maximising the value and use of water in urban areas, but so far lacks proper consideration of flood resilience. Synergistic integration between the ongoing knowledge on WSUD with flood resilience framework, can lead to establishing of a new model for water sensitive cities which are flood resilient, dealing with urban flooding in wiser manner while optimising the use of all kind of available resources.
Risk-informed flood risk management requires a comprehensive and quantitative risk assessment, wh... more Risk-informed flood risk management requires a comprehensive and quantitative risk assessment, which often demands multiple (thousands of) river and flood model simulations. Performing such a large number of model simulations is a challenge, especially for large, complex river systems (e.g., Mekong) due to the associated computational and resource demands. This article presents an efficient probabilistic modeling approach that combines a simplified 1D hydrodynamic model for the entire Mekong Delta with a detailed 1D/2D coupled model and demonstrates its application at Can Tho city in the Mekong Delta. Probabilistic flood-hazard maps, ranging from 0.5 to 100 year return period events, are obtained for the urban center of Can Tho city under different future scenarios taking into account the impact of climate change forcing (river flow, sea-level rise, storm surge) and land subsidence. Results obtained under present conditions show that more than 12% of the study area is inundated by t...
Alexandria (Egypt), similar to many other Arab cities in the Middle East and North Africa, experi... more Alexandria (Egypt), similar to many other Arab cities in the Middle East and North Africa, experiences occasional heavy rainfall and consequent pluvial flooding. For example, the last flood in Alexandria in 2015 led to wide-spread flooding in the city and caused huge damage and distress. The Assessment Report (version 5) of the Inter-Governmental Panel on Climate Change (IPCC) and the climate change impact assessment study of the World Bank predict that the situation will be exacerbated in the future. In the present research we carried out an analysis of the 2015 flood in Alexandria and concluded that a heavy rainfall could have been forecasted days ahead of the flooding event. As a follow up of the analysis we recommended the development of an early warning system to improve the preparedness of the city. The early warning system is seen as a risk reduction measure that will allow buying time to carry out more elaborate studies on larger investments to bolster flood prevention. Befo...
This paper presents a case study of a new adaptive, multi-level governance approach that supporte... more This paper presents a case study of a new adaptive, multi-level governance approach that supported a transition in river basin management in the Netherlands. The floods of 1993 and 1995 in the Netherlands triggered a paradigm shift in flood management. The 2.3 billion Euro flood safety programme Room for the River (RftR) was launched to increase flood safety by giving the rivers more room instead of merely enforcing the defence systems. This programme has been studied as a major stepping stone in the transition to integrated flood risk management: integrating spatial planning and flood risk management; and stimulating multi-level and multi stakeholder decision making. This research studied the outcomes of RftR beyond its mere delivery and how these outcomes came about. It comprised: 55 qualitative interviews, a survey amongst professionals and politicians (151) and extensive document analysis. First results indicate impact on: practice through guidelines in various disciplines; policy and regulation for e.g.: land use in outer marches; dyke requirements; regulation on soil and water quality; and other policy domains; scientific models and methods; and capacity building of people; organisational and management processes; and the creation and connection of networks. This outcome was obtained by stimulating social learning, within a multi-level programme organisation. This made it possible to signal, escalate and address barriers and opportunities for transition at the appropriate scale level and subsequently disseminate the lessons. For scholars in transition management and adaptive management RftR provides an example of a large-scale programme that changes the regime from within at the meso level.
As a result of the fast growth of remote sensing and data assimilation technology, many global la... more As a result of the fast growth of remote sensing and data assimilation technology, many global land use land cover (LULC) and climate reanalysis data sets have been used to advance our understanding of climate and environmental change. This paper investigates the precipitation variations of the Yangtze Delta Megalopolis by using precipitation reanalysis data under conditions of dynamic urban sprawl. Compared with current precipitation characteristic analyses, which are often based on a limited number of ground rainfall stations, the approach followed in this study comprises a grid-based statistical method using large sets of samples with a uniform distribution and a same representative grid area. This novel approach of dynamic sampling is applied in this study to overcome the temporal and spatial inconsistency of stationary sampling. This approach allows to examine the impact of urbanization on regional precipitation characteristics. The Yangtze Delta Megalopolis (YDM) region, one o...
Monitoring organic pesticides in surface water using grab water sampling method is ineffective in... more Monitoring organic pesticides in surface water using grab water sampling method is ineffective in most cases due to pesticides’ irregular emission and low solubility in water. To address the problem in water sampling method, this study used passive samplers (PS) composed of silicon rubber sheets (SR) and speedisk (SD). SR and SD were used respectively to measure hydrophobic and hydrophilic organic pesticides. These were submerged in river water uninterruptedly for 34 days. Pesticides in PS were extracted and analysed by sensitive analytical instruments HPLC, GC-MS MS and LC-MS MS. Pesticide assessment were conducted in two river systems in Cagayan de Oro River Basin, Philippines where agricultural run-off are unintentionally and continuously disposed from medium to huge plantations. The samplers were able to measure 105 emerging organic pollutants of which, 56 were organic pesticides and 22 organochlorine pesticides (OCP). Out of 56 pesticides, 11 were measured beyond the applied th...
Arbuscular mycorrhizal fungi (AMF) and its symbiosis with Canna indica on nitrogen (N) absorption... more Arbuscular mycorrhizal fungi (AMF) and its symbiosis with Canna indica on nitrogen (N) absorption was investigated for the remediation of contaminated soil. Canna indica plants with rhizome and leaf integrity intact were collected in spring and autumn seasons. To maintain the ideal nutrient composition, Hoagland concentrated nutrient solution was diluted with deionized water and additional nutrient solution was added periodically. Treated root samples were observed with an optical microscope and the number of hyphae and intersections as well as inoculation status were examined. High-throughput sequencing experiment was conducted to quantify AMF inoculation. Alpha diversity study was used to characterize abundance and diversity of the symbiosis. Hydroponic experiments were conducted to explore the absorption effectiveness of AMF-Canna symbiosis under different NH4+-N and NO3--N combinations. Hyphal colonization rate was only about 5.66 ± 1.08% in seedling stage in spring, but enhanced in the adult stage in autumn (53.89 ± 1.43%). Results revealed that AMF had no significant impact on NO3--N absorption by Canna roots, however, absorption of NH4+-N was improved by 63% under low concentration. Results revealed that when NH4+-N and NO3--N were applied combinedly in a 1:1 ratio, their respective absorption rates were enhanced to 99.63% and 99.50%. Compared with the case of NH4+-N as N source alone, synergistic effect of NH4+-N and NO3--N significantly changed the absorption of NH4+-N by C. indica, but its correlation with AMF inoculation was still not significant. Current findings could enhance understanding for effective N uptake and resource recovery.
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