Dr. Cecilia Tortajada and Prof. Dr. Janos Bogardi

“Water in megacities” dialogue forum hosted by the Munich Re Foundation on 10 May 2005

Urbanisation creates problems

Currently, there are 20 megacities worldwide, i.e. cities with over ten million inhabitants. Population explosion, water shortages, mountains of waste, transportation and natural catastrophes pose enormous challenges for municipal authorities. Taking Mexico City as an example, experts discussed the problem of water supply and sewerage at the Munich Re Foundation’s first dialogue forum on the subject of water.

On 10 May 2005, some 120 participants attended the first of a series of five dialogue evenings organised by the Munich Re Foundation. The series was timed to coincide with the Hypo Foundation for Culture’s “Water in Myth and Nature” exhibition, held at the Kunsthalle from 3 June to 21 August. At this first event, two leading experts discussed the topic “Water in megacities”: Dr. Cecilia Tortajada, Vice-President of the Third World Centre for Water Management in Mexico City, and Professor Janos Bogardi, Director of the UN University in Bonn. Professor Bogardi talked about the global challenges associated with water in metropolitan areas while Dr. Tortajada provided examples of water-related problems in Mexico City.

Up to 2015, the United Nations aims to halve the number of people with no access to drinking water and proper sanitation. According to Professor Bogardi, against the background of global population growth this means that sanitary facilities have to made available to an additional 342,000 people every day. The following example may help illustrate the scale of the problem: this would be the equivalent of a new sewage plant every four days for a city like Munich.

Professor Bogardi quoted dramatic figures to underline the urgency of the problem. “Every year five times more children die due to poor water quality than as a result of the December 2004 tsunami catastrophe”, the director of the UN university warned. It is the poorest members of society, i.e. those without access to the supply network, who have to pay a particularly high price for water from street traders. In some countries, the water they sell can cost up to 100 times more than tap water.

Mexico City, the world’s second-largest metropolis with over 20 million inhabitants, clearly illustrates the problem. Private households alone need 40 times as much water as in Munich. “There is actually enough water, but to guarantee an adequate supply, it has to be transported over a distance of up to 150 km, and an additional 1,000 m in altitude, a process that consumes a great deal of energy”, Cecilia Tortajada explained in her presentation. Some 30 to 40% of the water is lost in the course of distribution – enough to meet the needs of four million people! Dr. Tortajada drew attention to another problem: the constant pumping of the water means that the city is relentlessly sinking – in some places by up to 40 cm per year. Problems are caused by poor water quality and flooding due to effluents from the sewers following heavy rain. “Only 6% of the sewerage is treated”, said Dr. Tortajada. Overloading of the system makes maintenance difficult, since this would mean shutting down some sections.

Increasing urbanisation, in Professor Bogardi’s view an unstoppable trend, has made conurbations even more vulnerable to natural catastrophes. Whereas the average city had 200,000 inhabitants in the early 19th century, by 2000 this number had risen to 6.2 million. Most megacities are situated on the coast and are therefore particularly exposed to flooding. For a long time, people sensibly avoided the high-risk areas. But Professor Bogardi criticised the fact that this cautious attitude had been abandoned in the face of the population explosion. The poor sections of the population were being forced into the marginal areas.

Despite the considerable problems, the speakers were agreed that megacities not only harbour serious risks, they also offer enormous opportunities. Cities have better infrastructures than rural areas. The key to ensuring that these opportunities are exploited in the long term is a secure supply of water, and this requires a sensible urban development strategy. All options have to be taken into account, above all partnerships between municipal authorities and private enterprise.