The recent series of devastating hurricanes in the Caribbean has reminded the world, once again, that natural disasters are not equal-opportunity destroyers. The economically marginalized and those lacking secure land and property rights are often disproportionately affected for at least three reasons:
Can we rely only on satellite? How accurate are these results?
It is standard practice in classification studies (particularly academic ones) to assess accuracy from behind a computer. Analysts traditionally pick a random selection of points and visually inspect the classified output with the raw imagery. However, these maps are meant to be left in the hands of local governments, and not published in academic journals.
So, it’s important to learn how well the resulting maps reflect the reality on the ground.
Having used the algorithm to classify land cover in 10 secondary cities in Central America, we were determined to learn if the buildings identified by the algorithm were in fact ‘industrial’ or ‘residential’. So the team packed their bags for San Isidro, Costa Rica and Santa Ana, El Salvador.
Upon arrival, each city was divided up into 100x100 meter blocks. Focusing primarily on the built-up environment, roughly 50 of those blocks were picked for validation. The image below shows the city of San Isidro with a 2km buffer circling around its central business district. The black boxes represent the validation sites the team visited.
|Land Cover validation: A sample of 100m blocks that were picked to visit in San Isidro, Costa Rica. At each site, the semi-automated land cover classification map was compared to what the team observed on the ground using laptops and the Waypoint mobile app (available for Android and iOS).|
The buzz around satellite imagery over the past few years has grown increasingly loud. Google Earth, drones, and microsatellites have grabbed headlines and slashed price tags. Urban planners are increasingly turning to remotely sensed data to better understand their city.
But just because we now have access to a wealth of high resolution images of a city does not mean we suddenly have insight into how that city functions.
The question remains:
In an effort a few years ago to map slums, the World Bank adopted an algorithm to create land cover classification layers in large African cities using very high resolution imagery (50cm). Building on the results and lessons learned, the team saw an opportunity in applying these methods to secondary cities in Latin America & the Caribbean (LAC), where data availability challenges were deep and urbanization pressures large. Several Latin American countries including Argentina, Bolivia, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama were faced with questions about the internal structure of secondary cities and had no data on hand to answer such questions.
A limited budget and a tight timeline pushed the team to assess the possibility of using lower resolution images compared to those that had been used for large African cities. Hence, the team embarked in the project to better understand the spatial layout of secondary cities by purchasing 1.5 meter SPOT6/7 imagery and using a semi-automated classification approach to determine what types of land cover could be successfully detected.
Originally developed by Graesser et al 2012 this approach trains (open source) algorithm to leverage both the spectral and texture elements of an image to identify such things as industrial parks, tightly packed small rooftops, vegetation, bare soil etc.
What do the maps look like? The figure below shows the results of a classification in Chinandega, Nicaragua. On the left hand side is the raw imagery and the resulting land cover map (i.e. classified layer) on the right. The land highlighted by purple shows the commercial and industrial buildings, while neighborhoods composed of smaller, possibly lower quality houses are shown in red, and neighborhoods with slightly larger more organized houses have been colored yellow. Lastly, vegetation is shown as green; bare soil, beige; and roads, gray.
Want to explore our maps? Download our data here. Click here for an interactive land cover map of La Ceiba.
From East Asia, South Asia, and Africa to Latin America, disaster events such as hurricanes, floods, and earthquakes are on the rise, destroying homes and claiming lives.
Climate change is making it worse. , causing greater losses.
We may not know exactly what the world will look like in two decades, but we know this: it is going to be a world of cities.
Each year, urban areas are growing by an average of more than 75 million people – more than the population of the world’s 85 smallest countries combined.
For the world’s economy, this is great news, since cities produce 80 percent of global GDP, despite currently being home to only 55 percent of the population. But it is a problem for urban infrastructure, which can’t keep up with such fast-paced growth. As a result, – from flooding and landslides that can decimate informal housing settlements, to earthquakes that can devastate power grids and water systems.
These risks could be disastrous for the urban poor, 881 million of whom currently live in slums (up 28 percent since 2000). And climate change – which is increasing the intensity and frequency of natural disasters – will only exacerbate the problem. For this reason, multilateral and government institutions now see resilience and climate adaptation as integral pillars of development.
The Swiss State Secretariat for Economic Affairs (SECO), for example, considers low-emission and climate-resilient economies to be key to global competitiveness. A recent report by the World Bank and the Global Facility for Disaster Reduction and Recovery (GFDRR) found that climate change may force up to 77 million urban residents into poverty by 2030 – unless we take action to improve the resilience of cities around the world.
These are some of the views and reports relevant to our readers that caught our attention this week.
Populists and Autocrats: The Dual Threat to Global Democracy
In 2016, populist and nationalist political forces made astonishing gains in democratic states, while authoritarian powers engaged in brazen acts of aggression, and grave atrocities went unanswered in war zones across two continents. All of these developments point to a growing danger that the international order of the past quarter-century— rooted in the principles of democracy, human rights, and the rule of law—will give way to a world in which individual leaders and nations pursue their own narrow interests without meaningful constraints, and without regard for the shared benefits of global peace, freedom, and prosperity. The troubling impression created by the year’s headline events is supported by the latest findings of Freedom in the World. A total of 67 countries suffered net declines in political rights and civil liberties in 2016, compared with 36 that registered gains. This marked the 11th consecutive year in which declines outnumbered improvements.
Financial Flows and Tax Havens: Combining to Limit the Lives of Billions of People
Global Financial Integrity
Global Financial Integrity (GFI), the Norwegian School of Economics and a team of global experts released a study showing that since 1980 developing countries lost US$16.3 trillion dollars through broad leakages in the balance of payments, trade mis-invoicing, and recorded financial transfers. These resources represent immense social costs that have been borne by the citizens of developing countries around the globe. Funding for the report was provided by the Research Council of Norway and research assistance was provided by economists in Brazil, India, and Nigeria. Titled “Financial Flows and Tax Havens: Combining to Limit the Lives of Billions of People,” the report demonstrates that developing countries have effectively served as net-creditors to the rest of the world with tax havens playing a major role in the flight of unrecorded capital. For example, in 2011 tax haven holdings of total developing country wealth were valued at US$4.4 trillion, which exacerbated inequality and undermined good governance and economic growth.
The good news is that the world has a brief window of opportunity to make cities more resilient to climate change, natural disasters, and other stresses, as almost 60% of the urban area that will be built by 2030 is yet to be developed.
On January 22, 2012 at 6:00 am in the morning, Ethiopians living in the Efoyta Market neighborhood in Addis Ababa woke up to a burning five-story building. More than 13 hours later, the fire had killed two people, destroyed 65,000 square miles including several homes and businesses, and produced damages amounting to ETB 20 million ($1 million), a huge amount in a country where nearly 30% of the population live on less than $1.90 a day.
Cities are a puzzle for some and inspiration for others. As engines of economic growth, they are also hubs of rapid urbanization, a rising middle class, and a growing population. These three mega-trends drive global environmental degradation yet are only part of the important challenge facing cities today.
While consuming over two-thirds of global energy supply and emitting 70% of all carbon dioxide, cities are also uniquely vulnerable to climate change. Fourteen of the world’s 19 largest cities are located in port areas. With sea level rise and increased storm activity, these areas are likely to face coastal flooding, damage to infrastructure, and compromised water and food security. Under these conditions, meeting urban population’s growing production and consumption needs for food, energy, water, and infrastructure will overload rural and urban ecosystems.
To tackle these issues, the Global Environment Facility (GEF), in collaboration with the World Bank Group (WBG), launched the Sustainable Cities Program to engage 23 cities in 11 developing countries. Hailing from one of such countries, two urban development specialists working on each side of the Program explain why making cities more sustainable appeals to them.
- municipal finances
- inclusive cities
- low-carbon cities
- low-carbon development
- Energy Efficiency
- sustainable cities
- urban sustainability
- urban floods
- resilient cities
- urban resilience
- Public Sector and Governance
- Global Economy
- Climate Change
- Urban Development
- Sustainable Communities