Floods Management: Prevention, Protection and Mitigation
Water-Related Disasters account for about 90% of natural disasters globally. Global warming and climate change have resulted in a change in weather patterns around the world. In various regions, rainfall patterns have changed drastically resulting in unprecedented river flows. In recent years many parts of Kenya have received above-normal rainfall, this has resulted in flooding in various parts of the country. Some of the most affected regions are the lake basin region, Narok, lower Tana river basin, and lower Nzoia river basin. In the past few months, the water level in Lake Vitoria has been rising submerging nearby shopping centers, homes and farmlands. In 2014 there was a rise in water level in Lake Baringo resulting in flooding in nearby homes, hotels, and a school.
In India, floods have become a recurrent phenomenon, causing huge loss of lives and damage to livelihood systems, property, infrastructure, and public utilities in several parts of the country. As the country receives 80 percent of its precipitation during monsoons (June to September), constraints like the erosion of river-banks, drainage congestion, and indiscriminate encroachment of waterways lead to annual flooding in many parts
To minimize the impacts of floods there is a need for the government to formulate and implement flood disaster risk strategic plans. The plan should identify projects and activities necessary in the management of floods, it should also coordinate stakeholder activities. Mapping flood-prone areas and the use of satellite data in flood management is vital. To minimize the impacts of floods it is also important to invest in flood early warning systems.
Families living in flood-prone areas are at risk of losing their livelihood, property, and life. Poor families in these regions are some of the most vulnerable and require support when a flood disaster strikes. To cushion victims’ governments should design and implement disaster risk financing strategies for flood risk.
Mr. Johannes Orodi Odhiambo – Department of Environmental and Biosystems Engineering at the University of Nairobi
Dr. Beth Tellman – Post doctoral research scientist International Research Institute for Climate and Society at The Earth Institute, Columbia University
Prof. John Mutter – Professor of Earth and Environmental Sciences at the School of International and Public Affairs (SIPA), Columbia University
Prof. John Obiero – Senior Lecturer, Deptartment of Environmental and Biosystems Engineering at the University of Nairobi
Ms. Susmita Sengupta – Center for Science and Environment in India
Ms. Agnes Mbugua – CEO, Regional Centre on Groundwater Resource Education Training and Research
Dr. Murugi Ndirangu – Year in year out, tens of thousands of people are displaced from their homes and businesses due to flooding. Lives have been lost, homes have been swept my mudslides, and there has been an increase of water-borne diseases in destruction of crops and property. All these effects have had serious economic and social consequences our panel of experts from Kenya, India, and the United States into how we can mitigate, prevent, and ultimately city civilians from floods in their aftermath.
Prof. John Obiero – The aspect of flooding which is associated with an increase in the water level, especially in the river, as a result of increased discharge that emanates from heavy rainfall and from other parameters. This results in the overtopping of the river banks and then engaging the surrounding areas which very fertile heavy floodplains. In Kenya, most of the time, the actions could protect people against the flood, which involves emergency rescue operations. The circling people would be left to higher grounds quickly. One possible reason could be due to the inability to or failure to predict or forecast plans. One way of forecasting or predicting floods is that you make some hydrological modeling. A modern fiscal a representation of the real system and an example of such a system is the hydrologic system, which is a system that has a collection of components that interact in a certain manner. It is visualized as a volume in space, surrounded by a boundary that accepts water and other inputs, operates on the internally and produces outputs. (Time frame from minute 06:20-09:03)
Prof. John Obiero – Some of the features of hydrological model application in flood forecasting include: Hydrological modeling used in flood hazard mapping to provide information on inundation areas and inundation depths to help identify risk areas; Flood hazard maps for different return period by using remote sensing data and HEC-RAS, a hydrological modeling system used to carry out inundation analysis; Flood frequency analysis based on Gumbel extreme value; DEM serving as a major input in generation of input data for HEC-RAS. (Time frame from minute 13:13-15:31)
Ms. Susmita Sengupta – Urban floods is a hazard that is faced by generally cities and towns. They have a characteristic of very quick and very localized. Due to climate change, there will be a variability in the rainfall. The rainfall will come in a small space, and urban flooding will be caught due to this type of rainfall. Losing our bundles in the city is the reason of this flood. (20:34)
Ms. Susmita Sengupta – Urban sprawls, inadequate attention to the natural water bodies that exist there, building over many of the water bodies that block the smooth flow of water, lacking the art of drainage, and seeing the land for buildings but not for water impact the cause of urban flooding. (Time frame from minute 20:35-22:24)
Ms. Susmita Sengupta – What are actually the problems? Urban planners cannot see beyond land. Urban waterbodies or systems are seen only as ‘holes in the ground.’ Lakes and catchments are under different agencies. The degradation of water bodies are caused by the controlling and management agencies for the water bodies and their conflicting interests. The process of restoration gets delayed because of the lack of understanding the ecology of the water bodies. (Time frame from minute 26:23-28:19)
Ms. Agnes Mbugua – Climate change and increasing urbanization pose huge challenges in managing urban planning for a sustainable future. Casual factors include combinations of loss of previous are in urbanizing landscapes, inadequate drainage systems, blockade due to indiscriminate disposal of solid waste and building debris, encroachment of storm water drains housing in floodplains and natural drainage and loss of natural flood-storages sites. (Time frame from minute 31:44-33:32)
Ms. Agnes Mbugua – Designing an efficient drainage system, prevention and the risk management occupying an important part of public policy activities and the consideration of being major components in the process of sustainable development of territories, and mitigating flood hazard instead of eliminating them are the aspects of flood management. (Time frame from minute 33:34-35:01)
Ms. Agnes Mbugua – We are raising awareness of how we can manage these flood water to do managed aquifers recharge by flood water control, intending to increase the storage of groundwater, and preventing land subsidence disasters. There are also preliminary studies on physiography and hydrogeology in Nairobi City that is underway. (Time frame from minute 37:52-40:42)
Dr. Beth Tellman – The reason that satellite observation is so important is because modeling floods are actually very difficult to do. We’ve heard other panelists talk about flood like HEC-RAS that can be used to build representations of catchment and try to make predictions in computer about where flood risk is occurring, but a lot of these predictions are hard to make accurate, especially over large portions of the globe. (Time frame from minute 43:44-44:12)
Dr. Beth Tellman – Flood maps from satellites can used at every phase of disaster cycle to know where the event happened and to direct aid there, to direct recovery programs long-term after the disaster, and to look at the history of flooding. (Time frame from minute 49:05-49:20)
Prof. John Mutter – One thing I wanted to point out is this distinction we sometimes make between urban and rural flooding, which is not necessarily very clear. For instance, I know that flooding of the Mississippi River in New Orleans area is often caused by rain that’s occurring somewhere else up the Mississippi River in the rural hinterlands where agriculture is predominant. When it rains heavily there, the high water propagates down the urban Mississippi River and other rivers and into New Orleans. It could be a perfectly clear day in New Orleans with not a cloud in sight and the Mississippi River will just about be overtopping its banks because of rain somewhere else. So I know that urban flooding as a phenomenon can be characterized differently from rural flooding but there’s a connectedness there in many instances that we can’t overlook. (Time frame from minute 54:19-55:45)
Prof. John Mutter – In a global perspective, looking at all disaster everywhere over the last 30 to 40 years, floods, number one, in sense of occurrence, is more flood disasters in the model than any other sort of disaster and they are not the leading cause off death. They are not the leading cause of displacement and they are not the leading cause of economic disruption. (Time frame from minute 57:57-58:31)
Prof. John Mutter – Earthquakes causes the greatest mortality of all the natural disasters. Of course, Kenya being not prone to earthquakes, happily, other forms of disasters take precedent. In Kenya, flooding in particularly years can be the leading source of economic damage the leading source of displacement, the leading source of death, but on a global perspective, that’s not the case. (Time frame from 58:39-59:17)