With over 50% of the world population living in cities and a projected two-thirds of the population living in cities in 2030 (UN-Habitat), accurate weather forecasting becomes an important tool to respond timely and mitigate risks in cities. Extensive conurbations like the Pearl River Delta, Tianjin-Beijing, Yangtze River Delta, New York-Boston and (mega) cities like Tokyo, Sao Paulo, Jakarta, Manila, Los Angeles, Lagos, London, Hanoi, Bangalore have important features in common: dense populations, impervious built surfaces, significant emissions of pollutants, heat and waste, etc.(WMO). Large urban areas have differentiated weather patterns distributed across the city or metropolitan area. High resolution real-time weather forecasting becomes ever more important in order to forecast impacts, to communicate timely to urban populations at risk and to take right decisions in deploying emergency services in cities. It can also provide the evidence for adaptation measures among others the location of flood retention areas or the implementation of smart sewage systems that can be controlled as needed. High resolution weather forecasting can also provide diversified data on energy consumption and production of different neighbourhoods in the city and the way smart grids should respond to distributed peaks. In an urbanised world the weather forecast can no longer be seen as an external factor as the urban atmospheric conditions are impacted by emissions, pollution, heat island effects, urban form and other environmental factors. High resolution weather forecasting is increasingly focusing on air quality in addition to temperature, humidity and precipitation which is a signal that urban meteorology, climate and environmental research could evolve in more integrated city services (Urban Climate, Baklanov, Grimond). High resolution real-time weather forecasting for urban areas is a field that requires not only the technical instruments, data collection and interpretation, but also sophisticated comparative analysis between urban datasets available in cities, accurate algorithms, policies and governance models for risk mitigation.
Picture: Antony Pratap CC2.0
As reported in the Economist this week, Ho Chi Minh City “must take drastic action to prevent flooding”. The low-lying city with over 8 million inhabitants could learn from the Dutch that developed Smart strategies to cope with peak levels in its rivers.
According to the Economist “yet nearly half of the city lies less than one metre above sea level…”and scientists say groundwater extraction in Ho Chi Minh City causes land subsidence may be having a huge unseen effect to the city of which nearly 70% is already vulnerable to extreme flooding.”…”Flood risks are rising in Ho Chi Minh City’s lower lying districts, in part because the property boom that accompanied Vietnam’s 2007 entry to the World Trade Organisation led many developers to build wherever they could” and because of “poor immigrants who build flimsy shacks in the city’s swampy outskirts”. Instead of only investing in a plan that comprises of over 170 km of dikes to protect urban areas Dutch strategies like the ‘Room for the River’ program might offer new useful insights in how to create flood-control solutions that are sustainable. The Dutch ‘Room for the River’ program is not fighting the water with investing in dikes that have to be heightened every decade. ‘Room for the River’ offers a dynamic systems that offers solutions for the increasing amounts of water in the Dutch rivers and the gradually subsiding land behind the dikes. The ‘Room for the River’ project literally creates more room for the river and with that guaranteeing the safety of over 4 million people living in risk areas along it. Work is carried out in more than 30 locations and interventions comprise of for example high water channels that branches of the river and offer separate routes for high water or temporary water storage areas.
Some of the interventions go hand in hand with the development of urban areas that take water management as a basis for urban planning. The ‘Room for the River’ program is more than progressive engineering. Above all it is a paradigm shift from a defensive ‘total control’ attitude towards a concept with a dynamic system that creates new spatial opportunities within the river landscape. The dynamics of the Dutch water system itself is accurately mapped by ‘Rijkswaterstaat’ the governmental department that is responsible for the design and maintenance of the main infrastructure facilities in the Netherlands. Reliable water data is of great importance for controlling the flood barriers, sluices and pumping stations and the assessment of water quality. Therefore ‘Rijkswaterstaat’s measures include the daily tides, wave height and water quality. They also calculate water levels and wave forecasts. Something for Ho Chi Minh City to have a look at. To have total control with ‘hardware’ like dikes only will on the long term be very money-consuming. The dynamic ‘Room for the River’ project together with accurate data on water levels (the ‘software’) will set the example for future flood-control solutions across the globe. For a short introduction on the ‘Room for the River’ project have a look at the corporate video of Rijkswaterstaat. Picture: Ho Chi Minh City by Brian K. Smith. Sources: SmartCityStudio, Rijkswaterstaat, the Economist.
Hurricane Sandy has made it ever more clear: disaster control or emergency managment should be a priority in urban development and urban managment. People keep moving to urban areas, which become vulnerable when it comes down to natural disasters. Not in the least because they are often situated along coastlines and in delta’s. Here the impact of heavy weather and flooding this could cause is a primary concern. Disaster control or emergency managment requires some basic but elaborative concepts which are described by the ‘Division of Homeland Security and Emergency Services (DHS)‘ of the U.S.A. These include among others: Emergency Sheltering Provision, Dam Safety Preparedness and a Hazard Analysis Program. Emergency Sheltering requirements foresee in the provision of safe havens for large populations. These shelters require good accessibility and large scale sanitary infrastructure for example. Dam Safety Preparedness regulates the condition of the Dams in New York State. According to the DHS ‘There are approximately 400 high-hazard (Class C) and nearly 800 moderate-hazard (Class B) dams that pose a threat to jurisdictions in the event of a dam failure. Approximately 70 of the high-hazard dams produce hydroelectric power’..The Hazard Analysis Program ‘Hazny’, ‘is an automated hazard analysis program. HAZNY asks questions concerning hazards that you face and, based upon your responses, rates and ranks each hazard. It includes guidance on organizing a team approach in conducting the hazard analysis’. Planning and controlling cities in order to secure safety is a Smart approach but not new at all. The lay-out of many historic towns worldwide has been based on the concept of security, though disaster control in those days was primarely related to military defense. Safety and emergency managment has been on top of the urban agenda sinds 9/11, Hurricane Sandy is stressing again the necessity for a Smart infrastructure to cope with natural disasters. That might prevent New York against flooding and another blackout.
The 11th of July The Committee of Climate Change (CCC) published their report ‘Climate Change – is the UK preparing for flooding and water scarcity?’. One of their key messages is the one on the managment of surface water flows. ‘Flooding in urban areas is already increasing as a result of paving over green spaces in towns and cities’. Last decades towns and cities have been using ever less permeable surface materials. As a result of this heavy rainfall causes flooding in the city. This is a widely known problem within many European cities. This could be reduced by making cities greener and using more permeable surface materials in public space and private space. In many cities an old-fashioned sewer systems have been designed to handle the drainage of rainwater. With more soft and green surfaces in the city the overcharge of this system could be prevented. Another less obvious factor in the flooding of cities is the private garden. As the CCC explains: ‘Indicators show that in towns and cities the proportion of gardens that have been paved over increased from 28% of total garden area in 2001 to 48% in 2011. Total garden area in towns and cities has remained roughly constant at around 340,000 hectares of the 1.3 million hectares of total urban extent in England.’ Having a paved garden is easy and have been fashionable too for a long time. But a new trend in gardening could offer a solution. The ‘wild garden’ offers a new approach to gardening. A leading Dutch writer on gardening ‘Romke van der Kaa’ just published the book:’Naturalize, let the plant do the work’. As a Dutch internet bookseller describes: the book …’offers the adventure of plants that go their own way, whether or not directed by us. It delivers beautiful flower meadows, fields or prairie gardens, however small the garden is. An approach that fits comfortably with our current lifestyle, in which there is hardly any time for labor-intensive gardening.’ If the urban populations take up this trend it will contribute to flood prevention in the city.
Sendai Oasis – 1000 Rain Gardens, Tohoku University, Japan wins the Smart Cities Award at the Dutch Archtitecture Biënnale in Rotterdam.
According to the Netherlands Architecture Institute: “this project examines alternatives for the design of the city of Sendai, Japan, following the effects of the earthquake and tsunami in March 2011. In order to protect residents against extreme temperatures (heat islands) and from the effects of heavy rainfall, the Tohoku University proposes a network of small ‘rain gardens’. This network will provide a sustainable solution for water recycling and create green public spaces in the city. The jury was very impressed by the completeness of this plan, the whole seems to have a significantly larger impact than its individual parts.”
The Tohoku University which has been immediately rebuilt after the earthquake has a testgarden at the faculty terrain. According to the website of Sendai Oasis: “Creating a Sustainable City based on its Water System, Aobayama Rain Garden (ARG) proposes a multi-environmental control device that originally functions for the recovery of rain water, Infiltration areas and groundwater replenishment, thus acting as an effective environmental device linking the Keywords of Low-carbon society, Heat Island control, Energy recycling, Bio-diversity and Disaster aid spot with Emergency water supply. BY using ITC networks, real time monitoring is possible for all the data such as storage water levels, wind velocity related to thermal comfort index and green energy consumption degree via smart meters.”