Drainage Basins of the World’s Longest Rivers
Most of the earth’s surface is covered in water, but less than 1% of it is the fresh water that makes up the rivers and lakes we’re familiar with.
The water we encounter in life is moving through the stages of the water cycle. And even though rivers make up a tiny portion of all fresh water, they’re still one of the most visible parts of that cycle, especially for the billions of people who live in cities and towns built alongside them.
Of course, rivers don’t just appear out of nowhere. They’re the end result of water’s land-based journey–the product of many compounding inflows collected within a drainage basin.
The map above, from Reddit user r/CountZapolai, illustrates how massive the drainage basins can be for the world’s longest rivers.
What is a Drainage Basin?
A river’s drainage basin is defined as the area of land where precipitation collects and drains off, feeding the flow of rivers and their tributaries. Simply put, this is the process of water draining from higher points of land to lower laying areas–as demonstrated by the animation below.
In the case the world’s longest rivers, these drainage basins can span across entire continents and cross many international borders.
Fueling the World’s Longest Rivers
The longer a river system gets, the more terrain it passes through. It comes as no surprise then that the longest rivers are supported by immense drainage basins.
Here are the world’s top 10 longest rivers, and the size of their respective basins:
|Rank||River system||Length in miles (km)||Drainage area in miles² (km²)||Outflow||Countries in basin|
|East China Sea||🇨🇳|
|Gulf of Mexico||🇺🇸🇨🇦|
|6||Huang He (Yellow River)||3,395 |
|Gulf of Ob||🇷🇺🇰🇿🇨🇳🇲🇳|
|8||Río de la Plata||3,030 |
|Río de la Plata||🇧🇷🇦🇷🇵🇾🇧🇴🇺🇾|
|Sea of Okhotsk||🇷🇺🇨🇳🇲🇳|
Note: There is debate about the actual length of certain river systems. See a more comprehensive range of estimates here.
These 10 longest rivers alone are fed by a land area equivalent to the size of Africa.
Of those, the Amazon Basin is the largest in the world by far, covering one-third of the South American continent.
River Drainage Basins and Humanity
The fact that huge population centers sit at the terminuses of many of these key rivers is a testament to how important watersheds are to our survival. Only 10% of the global population lives further than six miles away from a surface freshwater body, and more often than not, that fresh water comes in the form of a river.
Noting where rivers begin their journey is also important as well. In the case of Tibet, many of the world’s longest rivers are fed by drainage basins that begin in the region. In fact, six of Asia’s major rivers begin on the Tibetan Plateau, meeting the basic needs of billions of people.
By illustrating the world’s longest rivers and their drainage basins, maps like this one help put into perspective the breathtaking complexity of Earth’s hydrological cycle.
Mapped: Human Impact on the Earth’s Surface
This detailed map looks at where humans have (and haven’t) modified Earth’s terrestrial environment. See human impact in incredible detail.
Mapped: Human Impact on the Earth’s Surface
With human population on Earth approaching 8 billion (we’ll likely hit that milestone in 2023), our impact on the planet is becoming harder to ignore with each passing year.
Our cities, infrastructure, agriculture, and pollution are all forms of stress we place on the natural world. This map, by David M. Theobald et al., shows just how much of the planet we’ve now modified. The researchers estimate that 14.6% or 18.5 million km² of land area has been modified – an area greater than Russia.
Defining Human Impact
Human impact on the Earth’s surface can take a number of different forms, and researchers took a nuanced approach to classifying the “modifications” we’ve made. In the end, 10 main stressors were used to create this map:
- Built-Up Areas: All of our cities and towns
- Agriculture: Areas devoted to crops and pastures
- Energy and extractive resources: Primarily locations where oil and gas are extracted
- Mines and quarries: Other ground-based natural resource extraction, excluding oil and gas
- Power plants: Areas where energy is produced – both renewable and non-renewable
- Transportation and service corridors: Primarily roads and railways
- Logging: This measures commodity-based forest loss (excludes factors like wildfire and urbanization)
- Human intrusion: Typically areas adjacent to population centers and roads that humans access
- Natural systems modification: Primarily modifications to water flow, including reservoir creation
- Pollution: Phenomenon such as acid rain and fog caused by air pollution
The classification descriptions above are simplified. See the methodology for full descriptions and calculations.
A Closer Look at Human Impact on the Earth’s Surface
To help better understand the level of impact humans can have on the planet, we’ll take a closer look three regions, and see how the situation on the ground relates to these maps.
Land Use Contrasts: Egypt
Almost all of Egypt’s population lives along the Nile and its delta, making it an interesting place to examine land use and human impact.
The towns and high intensity agricultural land following the river stand out clearly on the human modification map, while the nearby desert shows much less impact.
Intensive Modification: Netherlands
The Netherlands has some of the heavily modified landscapes on Earth, so the way it looks on this map will come as no surprise.
The area shown above, Rotterdam’s distinctive port and surround area, renders almost entirely in colors at the top of the human modification scale.
Resource Extraction: West Virginia
It isn’t just cities and towns that show up clearly on this map, it’s also the areas we extract our raw materials from as well. This mountainous region of West Virginia, in the United States, offers a very clear visual example.
The mountaintop removal method of mining—which involves blasting mountains in order to retrieve seams of bituminous coal—is common in this region, and mine sites show up clearly in the map.
You can explore the interactive version of this map yourself to view any area on the globe. What surprises you about these patterns of human impact?
Interactive Map: Tracking Global Hunger and Food Insecurity
Every day, hunger affects more than 700 million people. This live map from the UN highlights where hunger is hitting hardest around the world.
Interactive Map: Tracking Global Hunger and Food Insecurity
Hunger is still one the biggest—and most solvable—problems in the world.
Every day, more than 700 million people (8.8% of the world’s population) go to bed on an empty stomach, according to the UN World Food Programme (WFP).
The WFP’s HungerMap LIVE displayed here tracks core indicators of acute hunger like household food consumption, livelihoods, child nutritional status, mortality, and access to clean water in order to rank countries.
After sitting closer to 600 million from 2014 to 2019, the number of people in the world affected by hunger increased during the COVID-19 pandemic.
In 2020, 155 million people (2% of the world’s population) experienced acute hunger, requiring urgent assistance.
The Fight to Feed the World
The problem of global hunger isn’t new, and attempts to solve it have making headlines for decades.
On July 13, 1985, at Wembley Stadium in London, Prince Charles and Princess Diana officially opened Live Aid, a worldwide rock concert organized to raise money for the relief of famine-stricken Africans.
The event was followed by similar concerts at other arenas around the world, globally linked by satellite to more than a billion viewers in 110 nations, raising more than $125 million ($309 million in today’s dollars) in famine relief for Africa.
But 35+ years later, the continent still struggles. According to the UN, from 12 countries with the highest prevalence of insufficient food consumption in the world, nine are in Africa.
|Country||% Population Affected by Hunger||Population (millions)||Region|
|Burkina Faso 🇧🇫||61%||19.8||Africa|
|South Sudan 🇸🇸||60%||11.0||Africa|
|Sierra Leone 🇸🇱||55%||8.2||Africa|
|Syria 🇸🇾||55%||18.0||Middle East|
|Yemen 🇾🇪||44%||30.0||Middle East|
Approximately 30 million people in Africa face the effects of severe food insecurity, including malnutrition, starvation, and poverty.
Although many of the reasons for the food crisis around the globe involve conflicts or environmental challenges, one of the big contributors is food waste.
According to the United Nations, one-third of food produced for human consumption is lost or wasted globally. This amounts to about 1.3 billion tons of wasted food per year, worth approximately $1 trillion.
All the food produced but never eaten would be sufficient to feed two billion people. That’s more than twice the number of undernourished people across the globe. Consumers in rich countries waste almost as much food as the entire net food production of sub-Saharan Africa each year.
Solving Global Hunger
While many people may not be “hungry” in the sense that they are suffering physical discomfort, they may still be food insecure, lacking regular access to enough safe and nutritious food for normal growth and development.
Estimates of how much money it would take to end world hunger range from $7 billion to $265 billion per year.
But to tackle the problem, investments must be utilized in the right places. Specialists say that governments and organizations need to provide food and humanitarian relief to the most at-risk regions, increase agricultural productivity, and invest in more efficient supply chains.
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