Mythbusting the weather: Berlin’s rainy reputation belies a grave lack of water

Despite its abundant waterways and reputation for rainy weather, Berlin is in many ways as dry as Spain or Texas. Unsound water management in violation of European Union law is incurring punitive measures, but the issue is virtually unknown to the general public – and complicated by Berlin’s strange water system, the only one of its kind in the world.


Berlin is always viewed as a watery place: everyone loves the abundant rivers, canals and lakes, and hates the grim rainy fall and winter and the high water table that poses constant and costly flooding problems to basements and construction projects. The surprising truth, though, is that Berlin is a very dry place with dried-up forests, near-shortages of water, and extremely low rainfall, in fact less rain than parts of Spain, Italy, and most of the United States including Texas and Florida, with the obvious exceptions of the deserts and California’s Mediterranean zones and parts of the Great Plains. The climate crisis did not cause any of this, but it’s making everything worse.

Counterintuitively, it is possible for a region to be both cool and arid, to be lavishly endowed with bodies of water and flooded basements while simultaneously having low rainfall and being short of water in general. Berlin’s main river, the Spree, sometimes has so little water that the current virtually stops or even flows backwards. Some of this is natural and some is due to human activity: the low rainfall is normal for the region, as is the high water table, which is due to geology. Human activity, on the other hand, is the sole cause of the desiccation of forests and primary cause of the low river flow. These are all consequence of Berlin’s water resource management, historical events, and coal mining in the region. All the factors, natural and man-made, are being exacerbated by the climate crisis.

This is more than just trivia for weather fans. It means Berlin needs to manage its water supply just as meticulously as hot sunny arid places do. But Berlin hasn’t been doing that – the water company doesn’t even have a legal agreement with the city – leading to a host of problems.

First, a few basic numbers, all of them based on long-running averages that are just starting to be affected by the climate crisis:

Berlin gets very little rain: As measured by total annual precipitation, Barcelona gets more than Berlin, Naples almost twice as much, New York City and Houston more than twice as much and Miami almost three times as much.

…and very few rainy days: Houston has about as many rainy days per years as Berlin, New York fifteen percent more, and Miami one-third more.

 Precipitation per year (inches)  Number of rainy days per year
New Orleans63Glasgow, UK170
Miami62Buffalo167
New York50Portland164
Houston50Cleveland155
Atlanta50Pittsburgh151
Nashville47Seattle149
Glasgow44Cincinnati137
Boston44Miami135
St. Louis41Detroit135
Naples, Italy 40Cologne133
Munich, Germany 38Hartford130
Seattle38Dublin, Ireland 129
Dublin, Ireland 30New York122
Barcelona, Spain 25St. Louis113
London, UK22London, UK109
Berlin, Germany 23Berlin, Germany 106
Houston104

Berlin has a considerable risk of water shortages: Its “water stress” – and that of about half of Germany – is rated as “high” by experts, which designates places that use between 40 to 80 percent of their available water every year. They will be dangerously close to running out of water if a run of dry years were to occur or if the city were to grow rapidly, which in fact Berlin already is doing, as one of the fastest-growing cities of Europe and for that matter the U.S. (Normally, water supplies are renewed naturally by precipitation and river flow, but climate change could reduce the replenishment.) By comparison, very few places in the U.S. apart from the Great Plains and deserts or anywhere in Africa are rated high or above.

Water stress measured as percent of available water used annually. Five categories ranging from low (pale yellow, <10%) to very high (dark red, >80%). Germany outlined in green. (WRI)

 

Berlin’s risk of drought is significant: The city has a medium-high risk of drought, which is higher than all of North America and the large majority of Africa excluding deserts. “Drought” here is defined not just as lack of rain, but also by how dependent each place is on the rain, such as how heavily the economy relies on rain-fed agriculture and how long its reserves of drinking water would last in a drought.

Drought risk on a scale from 0 to 1 based on a calculation involving multiple climatic, economic and social factors (WRI)

 

While basements are flooding, forest soils are drying out


The consequences of acting like there’s a lot of water available when there isn’t are already visible. Soils in the state forests on the outskirts of the city are drying out, resulting in the degradation of endangered wetland and bog habitats that have legal protections (like endangered species do) under European Union law. This has triggered legal action by the EU which will result in steep fines if the city does not reverse the trend.

The desiccation is caused by, of all things, a lowered water table – exactly the opposite problem to the flooded basements –  which in turn is caused by the city drawing water from aquifers situated underneath the forests instead of from other possible sources. The reason Berlin uses these particular aquifers is that it obtains all its drinking water from within the city limits. It is the only large city in the world that does this.

A water-supply system unique in the world – for good reason

 

All other cities obtain much or all of their water from whatever source – underground aquifer, river, lake – is most abundant and practical, regardless of whether it is located in the city proper. There is absolutely no special reason why any city should get all its water from within the official city limits and nowhere else, no more than cities should grow all their food or only use wood from their own trees or quarry their own stone for buildings. This has nothing to do with the indisuptably wise practice of consuming local food, where “local” means “grown within 100 miles or so”. No one anywhere is proposing to define “local food” as “within the city limits”, but that is precisely the boundary that delimits Berlin’s water sources.

For the quantities that a city needs, it makes more sense to get its water from sources in the region that lie outside its borders but are more abundant and, ideally, cause less harm to the environment, than from sources that are on-site but scarcer, more harmful to the environment and/or more expensive to manage. The latter is what Berlin does.

Centuries of decentralization have left their mark

 

The situation is a bizarre, costly and environmentally harmful relic of Berlin’s unusual 800-year history that has resulted in a piecemeal, ununified water system. To trace its origins you have to start with the fact that until the very late date of 1871, Germany was not a nation in the usual sense of the term and Berlin was never a national capital, with all that implies, like France and Paris had been for centuries, or England with London, or Italy with Rome. Berlin had only been the capital of one particular medium-sized kingdom (Prussia) among dozens, at times hundreds, of mini-kingdoms and dukedoms and the like that only formed loose, shifting, decentralized associations like the Holy Roman Empire and never a nation per se.

Even after Germany became a nation in 1871, the place we call Berlin wasn’t one city but eight separate cities and towns and 86 communities, all administratively independent. Finally in 1920 they were consolidated into 20 boroughs, later 23, then consolidated again into 12 in 2001.

Government in tredecuplicate

 

But these boroughs have nothing in common with the boroughs, districts or wards in other cities. Each has a complete and autonomous city government with its own mayor, council, assembly with members drawn from subdistricts within the borough, a full suite of administrative departments and its own autonomous self-contained budget. But this all exists at the citywide level too, resulting in tredecuplicate (like duplicate, but for 13) administrations – 13 fully separate city planning departments that are autonomous and not subdivisions of a central department, 13 separate autonomous parks departments, 13 separate health departments, 13 housing departments, 13 education departments, 13 streets departments, 13 of everything, in a city smaller than Minneapolis/St. Paul.

Although “autonomous” isn’t entirely accurate. In fact they exist in a quantum Schrödinger’s cat state where they are subordinate and not subordinate to the central administration at the same time and no one really knows who has the final say.

All this decentralization reduced if not eliminated incentives to build a citywide water system. Then World War II intervened, and afterwards when East and West Berlin were part of separate countries, comprehensive citywide water planning was again not possible. This set the city on its course of not getting any water from the surrounding rural state of Brandenburg where there is more supply and less demand.

After reunification in 1990, Berlin cobbled together a municipal water system from what was there before, without citywide integration to say nothing of regional integration. Many parts of the city have to autonomously obtain their own water; water can’t be moved between them to suit demand and supply. The result is that some districts with forest lands, including critical wet bog forests, can only get their water from aquifers lying beneath the forests, which lowers the water table and dries out the soil. And that’s how you get from the 500-odd sovereign principalities of the Holy Roman Empire to the EU threatening Berlin with fines for habitat destruction.

Unintended consequences: when reducing coal mining increases pollution

 

It somehow fits with Berlin’s surreal history that the closing of coal mines results in an increase in its river pollution. The Rube Goldberg chain of events works as follows.

On the river Spree upstream of Berlin is a major coal mining region. Several coal mines there have been closed. After closure, the mines are flooded, that is, water fills the space where the coal used to be (the coal, of course, is now floating in the atmosphere in the form of carbon dioxide, having been burned.) The water for this comes from the river. The volume is so great that it dramatically lowers the water level of the river and will do so for decades until the mines are filled. Now the Spree has significantly less water than it used to, but the same amount of pollution, such as sulfur compounds from the mines that are still open, and nitrogen from agricultural runoff. So the pollutant concentration is now higher, enough so to be significantly more harmful to human health and ecosystems that it already was. (Picture adding five spoons of sugar to a whole pot of coffee as opposed to five spoons of sugar in one cup.)

The water pollution levels are high enough to be in violation of European Union regulations. As is the case for the degradation of the wetlands, the EU has initiated so-called infringement proceedings against Berlin, which will lead to stiff fines if Berlin does not improve its water quality.

It goes without saying that, despite the reduced river flows, closing coal mines is a net benefit for the environment due to avoided carbon emissions and the direct impacts of the mining itself. Climate change or no climate change, the mines would get shut down sooner or later anyway, either because they ran out of coal or ceased to be price-competitive with wind and solar. Keeping the mines open to retain the river flows is an option that physically doesn’t exist.

 


Technical Background

 

Maps are from the World Resources Insitute’s Water Risk Atlas 2019.

Definitions of terms

Adapted from Water Risk Atlas background information

Baseline water stress measures the ratio of total water withdrawals to available renewable surface and groundwater supplies. “Withdrawals” means domestic, industrial, irrigation, and livestock uses, both nonconsumptive and consumptive. Nonconsumptive use means water that is withdrawn and then returned to the source, such as when a factory uses water from a river for cooling or cleaning and then returns it to the river. Consumptive use means water that is not directly returned, such as for agriculture where the water ends up in the crop itself or evaporated into the atmosphere.

Available renewable water supplies include the impact of upstream consumptive water users and large dams on downstream water availability. Higher values indicate more competition among users. The ratio of water used to water available as a percentage is converted to the following risk categories:

Drought risk measures where droughts are likely to occur, the population and assets exposed, and the vulnerability of the population and assets to adverse effects. Higher values indicate higher risk of drought.

It is calculated using a formula that incorporates the hazard itself (lack of rain based on historical data), the exposure (the density of population and agriculture that would be affected by drought), and the vulnerability (how sensitive to drought are various social, economic and infrastructure factors – place with high population have high exposure, but if they have ample backup supplies stored in reservoirs their vulnerability is low).

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