4/17/2011

Document sharing: Arup's UrbanLife report: Water Resilience for Cities

You may have already downloaded this document available on Arup. If not, let me share with you what I am currently reading again: Arup UrbanLife report: Water Resilience for Cities.
What is this report about?
Briefly, Arup's UrbanLife lab recently reported a set of strategic recommendations the firm has developed for the C40 Cities Group, Arup announces. I paste here what the lab wrote:

Delivering a city's climate change strategy requires an understanding of the issues they face — water resources, energy supply, transport systems and waste — in terms of planning, technical implementation and the policy interventions needed to make solutions a reality.
The report is free of charge and is very instructive.

I will not summarize Arup's report. I will however quote a series of key issues, precisely 7 key issues that cities will be facing in the close future:
  1. Sea levels on the rise of 480 millimeters by the year 2100 —> Flooding will increase, affecting the hundreds of millions of people who live in cities situated close to vulnerable coastlines, river flood plains and river deltas.
  2. Extreme weather events —> Such as tropical storms, are expected to become more frequent while rainfall is predicated to become more intense, even as some areas receive less rainfall than usual.
  3. Reductions in fresh water stores —> where there are higher rates of evaporation, prompted by increased temperatures, drier soils will soak up more water, reducing the recharge of underground aquifers and the flow of fresh water springs. Higher temperatures will reduce the amount of water springs. As fresh water reserves found in glaciers and snow fields diminish, cities will be pressed to find new ways to store water to meet growing demand throughout the year. (…) Estimates suggest that climate change will account for about 20% of the increase in global water scarcity.
  4. Water scarcity —> affects hundreds of millions of urban dwellers worldwide. Climate change will exacerbate this, as prolonged droughts and spreading destertification will increase the stress on already-stretched water resources. (…) The result could be reductions in available water for drinking, household use and industry.
  5. Water quality issues —> will become a further concern for some urban areas. Changes in the amounts on patterns of precipitation may change the route and residence of water in the water in the watershed, in turn affecting its quality. Regardless of water quantity, water could become unstable for use.
  6. Salination —> For coastal cities, water quality is likely to be affected by salination, or increased quantities of salt in water supplies. This will result from a rise in sea levels, which can increase salt concentrations in groundwater and estuarine rivers. At times of low rainfall, city water managers will find it more difficult to release fresh water from reservoirs when needed for salinity control. The problem becomes even worse in regions where the dry season extends. (…) The result can be greater inundation of salt water which runs the risk of overloading water treatment systems. More intense rainfall may cause overloading of drainage systems, increasing cities' vulnerability to flooding and reducing the level of flood protection.
  7. Reduced food security —> Climate change could threaten food security as agricultural activity in the tropics and sub-tropics is forecast to slow because of rising temperatures and drought. As demand for water intensifies under the climate change, effective methods for managing water resources and demand will become essential.

Arup has elaborated recommendations. I will quote some of them. Cities need to ensure a resilient water supply as climate and populations grow requires cities to introduce active water resource management measures. What Arup recommends is to consider a combination of increasing raw water storage capacity, combating salination, implementing demand management and improving river basin management:

  1. An investment in urban water security —> Cities need to ensure to have sufficient water storage capacity. (…) Increasing water storage capacity can be regarded as an investment in greater urban water security and reliability. New groundwater and surface water storage will ensure a reliable water supply, and provide vital flood protection by managing more variable precipitation and runoff.
  2. Alternative storage solutions —> natural storage, such as groundwater storage, wetlands and lakes, community tanks, and smaller scale reservoirs.
  3. Combating salination —> meaning a raw water storage that is protected from the effects of salination and can allow continued production of water at treatment plants when water becomes temporarily too saline; and to desalinate brackish water, that is to say to improve water treatment by introducing a desalination process for brackish water operates alongside the conventional treatment of surface water.
  4. Implementing water demand management —> The need for demand management policies, water conservation measures — reducing waste from water transmission system and networks, recycling water, using water-efficient or water-saving devices, fiscal measures to ensure that water goes to the highest socio-economic value users, such as domestic and industrial users; ensuring that rivers remain healthy and beneficial as ecosystems.
  5. Social and economic benefits —> it can be a service a larger population in the future.
  6. Improving river basin management —> National assets on international boundaries, transboundary agreements, flood management.

These core elements mentioned above are some recommendations among others that the report has collected. In few words, it aims at opening new discussion and approaches on water resilience. Water management will be one of the key elements in urbanism in the close future. Water is already considered as the problem of 21st century cities, specifically if we do not elaborate rapidly mitigation measures, not in terms local, but in terms of local and transnational as Arup suggests.
The document is available on Arup.

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