On September 9, 2015, typhoon number 18 brought unprecedented rainfall to northern Japan, particu... more On September 9, 2015, typhoon number 18 brought unprecedented rainfall to northern Japan, particularly to Kanto and Tohoku regions. As a result, flood damage and sediment disasters occurred in various locations including an overflow in Kinu River at Wakamiyado and levee failure in Kinu River at Misaka-cho. During the disaster, upstream of Kinu River has received more than 600 mm precipitation in 48 hrs which is more than twice the amount which usually received throughout the entire month of September. This unprecedented rainfall, has caused huge disaster to the people in Ibaraki prefecture particularly Joso city where the entire city has been recoded an inundation of about 1-2 m depth and it has been over 3 m in some areas. A small river (Hachikenbori River) flowing through the center of the flood plain was assumed to be the cause for earlier inundations in the downstream. We developed a coupled flood inundation model for the area with 1D and 2D hydrodynamic models, to study the effect of the Hachikenbori River for the inundations. The model includes the overbank flow and the flow due to river bank failure in Kinu River and Hachikenbori River. The developed model was validated with the observed data of inundations and water levels at Hachikenbori River. The results from the analyses performed with and without Hachikenbori River indicate that Hachikenbori River caused the early inundations in some places. Numerical results suggest that the Hachikenbori River has reduced the inundation area by 1 km 2 by allowing the flood water to pass quickly. However, there is no difference in the inundation heights of the cases carried out with and without Hachikenbori River.
The development of numerical models to simulate the real time situations is important to find pos... more The development of numerical models to simulate the real time situations is important to find possible solutions for natural disasters. Numerical models can also evaluate the effectiveness of the possible solutions by analyzing various scenarios. Coupled 1D and 2D hydraulic models play a significant role in analyzing flooding problems. Kubokawa, Japan had undergone flooding in 2014. We developed a detailed flood inundation model incorporating the available pumps, flood gates and other components in order to analyze possible countermeasures for mitigation of floods in the future. The model includes rainfall runoff models, a 1D river model and a 2D river basin model. The developed model was verified using field observation data of high water levels in the river and the inundations of the area. The results from the numerical model and field survey data indicate that the main causes for the flooding are the bathymetry of the area (i.e., the low lying areas in the surrounding high elevations) and the flow from the surrounding mountain. It was also found that the river has not overflowed. In this study, several countermeasures were identified to potentially mitigate future flooding. They include constructions of two retention ponds and a bypass channel for the inflow from surrounding mountain area. This paper summarizes the development of numerical model and the analysis performed to evaluate the effectiveness of such flood mitigation measures.
ABSTRACT
Colombo, the commercial capital of Sri Lanka, is located in the flood plains of the Kel... more ABSTRACT Colombo, the commercial capital of Sri Lanka, is located in the flood plains of the Kelani River. Therefore, Colombo is more vulnerable to flooding during the heavy rainy seasons (April-June and September-November). Furthermore, it has been identified that Colombo has undergone climate changes over the past years with very random change of rainfall anomalies. This study was focused on analyzing the extreme flooding scenarios due to climate change in Colombo area. Future climate conditions in the Kelani basin with different Global Circulation Model (GCM) data was analyzed to define extreme rainfall scenarios for the Kelani basin taking future climate change into account. Flood inundations in Colombo area under extreme rainfall scenarios were modeled and possible adaptation measures were identified to reduce the impacts in the area.
The development of numerical models to simulate the real time situations is important to find pos... more The development of numerical models to simulate the real time situations is important to find possible solutions for natural disasters. Numerical models can also evaluate the effectiveness of the possible solutions by analyzing various scenarios. Coupled 1D and 2D hydraulic models play a significant role in analyzing flooding problems. Kubokawa, Japan had undergone flooding in 2014. We developed a detailed flood inundation model incorporating the available pumps, flood gates and other components in order to analyze possible countermeasures for mitigation of floods in the future. The model includes rainfall runoff models, a 1D river model and a 2D river basin model. The developed model was verified using field observation data of high water levels in the river and the inundations of the area. The results from the numerical model and field survey data indicate that the main causes for the flooding are the bathymetry of the area (i.e., the low lying areas in the surrounding high elevations) and the flow from the surrounding mountain. It was also found that the river has not overflowed. In this study, several countermeasures were identified to potentially mitigate future flooding. They include constructions of two retention ponds and a bypass channel for the inflow from surrounding mountain area. This paper summarizes the development of numerical model and the analysis performed to evaluate the effectiveness of such flood mitigation measures.
On September 9, 2015, typhoon number 18 brought unprecedented rainfall to northern Japan, particu... more On September 9, 2015, typhoon number 18 brought unprecedented rainfall to northern Japan, particularly to Kanto and Tohoku regions. As a result, flood damage and sediment disasters occurred in various locations including an overflow in Kinu River at Wakamiyado and levee failure in Kinu River at Misaka-cho. During the disaster, upstream of Kinu River has received more than 600 mm precipitation in 48 hrs which is more than twice the amount which usually received throughout the entire month of September. This unprecedented rainfall, has caused huge disaster to the people in Ibaraki prefecture particularly Joso city where the entire city has been recoded an inundation of about 1-2 m depth and it has been over 3 m in some areas. A small river (Hachikenbori River) flowing through the center of the flood plain was assumed to be the cause for earlier inundations in the downstream. We developed a coupled flood inundation model for the area with 1D and 2D hydrodynamic models, to study the effect of the Hachikenbori River for the inundations. The model includes the overbank flow and the flow due to river bank failure in Kinu River and Hachikenbori River. The developed model was validated with the observed data of inundations and water levels at Hachikenbori River. The results from the analyses performed with and without Hachikenbori River indicate that Hachikenbori River caused the early inundations in some places. Numerical results suggest that the Hachikenbori River has reduced the inundation area by 1 km 2 by allowing the flood water to pass quickly. However, there is no difference in the inundation heights of the cases carried out with and without Hachikenbori River.
The development of numerical models to simulate the real time situations is important to find pos... more The development of numerical models to simulate the real time situations is important to find possible solutions for natural disasters. Numerical models can also evaluate the effectiveness of the possible solutions by analyzing various scenarios. Coupled 1D and 2D hydraulic models play a significant role in analyzing flooding problems. Kubokawa, Japan had undergone flooding in 2014. We developed a detailed flood inundation model incorporating the available pumps, flood gates and other components in order to analyze possible countermeasures for mitigation of floods in the future. The model includes rainfall runoff models, a 1D river model and a 2D river basin model. The developed model was verified using field observation data of high water levels in the river and the inundations of the area. The results from the numerical model and field survey data indicate that the main causes for the flooding are the bathymetry of the area (i.e., the low lying areas in the surrounding high elevations) and the flow from the surrounding mountain. It was also found that the river has not overflowed. In this study, several countermeasures were identified to potentially mitigate future flooding. They include constructions of two retention ponds and a bypass channel for the inflow from surrounding mountain area. This paper summarizes the development of numerical model and the analysis performed to evaluate the effectiveness of such flood mitigation measures.
ABSTRACT
Colombo, the commercial capital of Sri Lanka, is located in the flood plains of the Kel... more ABSTRACT Colombo, the commercial capital of Sri Lanka, is located in the flood plains of the Kelani River. Therefore, Colombo is more vulnerable to flooding during the heavy rainy seasons (April-June and September-November). Furthermore, it has been identified that Colombo has undergone climate changes over the past years with very random change of rainfall anomalies. This study was focused on analyzing the extreme flooding scenarios due to climate change in Colombo area. Future climate conditions in the Kelani basin with different Global Circulation Model (GCM) data was analyzed to define extreme rainfall scenarios for the Kelani basin taking future climate change into account. Flood inundations in Colombo area under extreme rainfall scenarios were modeled and possible adaptation measures were identified to reduce the impacts in the area.
The development of numerical models to simulate the real time situations is important to find pos... more The development of numerical models to simulate the real time situations is important to find possible solutions for natural disasters. Numerical models can also evaluate the effectiveness of the possible solutions by analyzing various scenarios. Coupled 1D and 2D hydraulic models play a significant role in analyzing flooding problems. Kubokawa, Japan had undergone flooding in 2014. We developed a detailed flood inundation model incorporating the available pumps, flood gates and other components in order to analyze possible countermeasures for mitigation of floods in the future. The model includes rainfall runoff models, a 1D river model and a 2D river basin model. The developed model was verified using field observation data of high water levels in the river and the inundations of the area. The results from the numerical model and field survey data indicate that the main causes for the flooding are the bathymetry of the area (i.e., the low lying areas in the surrounding high elevations) and the flow from the surrounding mountain. It was also found that the river has not overflowed. In this study, several countermeasures were identified to potentially mitigate future flooding. They include constructions of two retention ponds and a bypass channel for the inflow from surrounding mountain area. This paper summarizes the development of numerical model and the analysis performed to evaluate the effectiveness of such flood mitigation measures.
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Papers by chamila Niroshinie
Colombo, the commercial capital of Sri Lanka, is located in the flood plains of the Kelani River. Therefore, Colombo is more vulnerable to flooding during the heavy rainy seasons (April-June and September-November). Furthermore, it has been identified that Colombo has undergone climate changes over the past years with very random change of rainfall anomalies. This study was focused on analyzing the extreme flooding scenarios due to climate change in Colombo area. Future climate conditions in the Kelani basin with different Global Circulation Model (GCM) data was analyzed to define extreme rainfall scenarios for the Kelani basin taking future climate change into account. Flood inundations in Colombo area under extreme rainfall scenarios were modeled and possible adaptation measures were identified to reduce the impacts in the area.
Colombo, the commercial capital of Sri Lanka, is located in the flood plains of the Kelani River. Therefore, Colombo is more vulnerable to flooding during the heavy rainy seasons (April-June and September-November). Furthermore, it has been identified that Colombo has undergone climate changes over the past years with very random change of rainfall anomalies. This study was focused on analyzing the extreme flooding scenarios due to climate change in Colombo area. Future climate conditions in the Kelani basin with different Global Circulation Model (GCM) data was analyzed to define extreme rainfall scenarios for the Kelani basin taking future climate change into account. Flood inundations in Colombo area under extreme rainfall scenarios were modeled and possible adaptation measures were identified to reduce the impacts in the area.