Making Ulaanbaatar More Resilient to Floods
After growing up in Manila, one of the densest and most cyclone-prone cities in the world, I expected my first visit to Mongolia to be filled with vast plains and blue skies. The plains and skies did not disappoint – but I quickly learned that Ulaanbaatar, the country’s capital, is a city that is rapidly becoming like many other cities where I have lived and worked.
There is the unmistakable buzz of a place that is growing, and growing fast. People move to Ulaanbaatar from the countryside for the opportunities that open up to them, with the city now home to nearly half the country’s population. It is becoming more cosmopolitan every time I go – there is even a Cuban restaurant with a Cuban chef. And, like many other cities in Asia, Ulaanbaatar has floods.
Out of the 34 floods recorded from 1915-2013, about 60% occurred from 2000-2009. The 1966 flood stood out in collective memory as being the last “big one.” Yet in 1966, Ulaanbaatar only had a population of over 200,000, now it has over 1.3 million people.
It is estimated that the city faces over $80 million in economic losses, if a 1966-sized flood were to happen again, according to a Flood Risk Management Strategy adopted by the Municipality of Ulaanbaatar in June 2015. More than 200,000 people, 600 residential buildings, 31,000 gers (traditional portable dwellings used by nomads) and 109 schools, kindergartens, and medical units are located in medium to high flood hazard areas. This does not include critical infrastructures such as the high-voltage power station that sits in the middle of the Selbe river channel.
Urban planning and growth that were not based on understanding of flood risks is a major challenge for this semi-arid city. By law, all Mongolian citizens can claim 700 square meters of land for residential use in and around Ulaanbaatar. This has led to tremendous spatial expansion of ger areas into hazardous mountain slopes and flood plains. These areas, often home to lower-income migrants, are largely unplanned and lack basic services and infrastructure, making them more vulnerable to the impacts of flooding.
Other factors come into play as well. Poor solid waste management has congested a significant proportion of the city’s natural and artificial drainage systems. Many sections of existing levees and drainage structures have been demolished to make way for new construction, while the remaining sections are poorly operated and maintained. Rivers are heavily sedimented, which further reduces the conveyance capacity of the drainage system.
Given the many causes of flood risk in Ulaanbaatar, the historical approach of expanding flood control (structural) measures in the city will not be sufficient to manage the growing risk. High-intensity rainfall in the summer, which used to be the main cause of flooding in Ulaanbaatar, is no longer the only cause.
With this in mind, the Flood Risk Management Strategy includes a range of possible risk management actions.
Based on a rigorous flood risk assessment and in-depth consultations with communities, experts and stakeholders from various sectors, the municipality developed five strategic directions to mitigate floods:
- Protected river basins: Rehabilitation of the Tuul and Kharaa river basins, including conservation, forest protection to reduce soil erosion and increase water retention capacity to reduce runoff;
- Resilient urban development: Reduction of flood exposure and vulnerability by making sure land use, sediment and solid waste management are risk-informed and upgrading urban infrastructure;
- Improved flood infrastructure: Enhancement of flood protection infrastructure and their capacities, and improvement of drainage networks, particularly in the ger areas;
- Safe people and resilient communities: Reduction of the vulnerability of people, households and communities through improving social and emergency services, early warning, disaster preparedness and community-based disaster risk management; and
- Good governance and effective flood risk management: Institutional strengthening and rationalization of roles and responsibilities of various agencies with mandates related to flood risk management.