A WWF/World Bank publication explaining the importance of protected forests to sustainable drinking water supplies for the world's biggest cities

Introduction

Over the past 100 years, the world population has grown three times. With the rise in population, the number of cities has also increased from 43 cities in 1900 to around 800 cities in 1990.
 
On the one hand, the demands of these developments are creating increasing pressure on many governments to justify the continued protection of forest areas, since alternative uses of lands usually promise higher economic benefits. On the other, the same developments are responsible for shortage of regular supply of drinking water. There is a link between supply of high quality drinking water and forest protected areas. Many of the world's cities rely on protected forests for some or all of their water supply requirements. 
 
Running Pure is a research report sponsored by the World Bank/WWF Alliance for Forest Conservation and Sustainable Use. Till recently, biodiversity was the central value in the arguments for protected areas. This report seeks to develop wider arguments for protection, focusing on the potential role of protected areas in helping to maintain water supply to major cities.

1. The importance of forest protected areas to drinking water

The report discusses the links between protected areas and drinking water. It identifies the issues related to watersheds and protected areas, the benefits of managing these areas effectively, and how to make it economically viable and socially sustainable. Some of the key conclusions in the report are summarized as:

Well managed natural forests provide benefits to urban populations in terms of high quality drinking water:

* Well managed natural forests almost always provide higher quality water, with less sediment and fewer pollutants, than water from other catchments
* Some natural forests (particularly tropical montane cloud forests and some older forests) also increase total water flow, although in other cases this is not true and under young forests and some exotic plantations net water flow can decrease Impacts of forests on security of supply or mitigating flooding are less certain although forests can reduce floods at a local headwater scale
* As a result of these various benefits, natural forests are being protected to maintain high quality water supplies to cities
* Protection within watersheds also provides benefits in terms of biodiversity conservation, recreational, social and economic values
* However, care is needed to ensure that the rural populations living in watersheds are not disadvantaged in the process of protection or management for water quality
 
Maintaining high quality water supply is an additional argument for protection:

* Many important national parks and reserves also have value in protecting watersheds that provide drinking water to towns and cities
* Sometimes this is recognised and watershed protection was a major reason for establishing the protected area. Sometimes such watershed protection has bought critical time for biodiversity, by protecting natural areas around cities that would otherwise have disappeared
* In other cases, the watershed values of protected areas have remained largely unrecognised and the downstream benefits are accidental
* Where forests or other natural vegetation have benefits for both biodiversity and water supply, arguments for protection are strengthened with a wider group of stakeholders
* In some cases, full protection may not be possible and here a range of other forest management options are also available including best practice management (for example through a forest management certification system) and restoration
 
The watershed benefits of forest protected areas could help pay for protection:

* The economic value of watersheds is almost always under-estimated or unrecognized
* It is possible to collect user fees from people and companies benefiting from drinking water to help pay for the catchment protection benefits provided by protected area management - although only in certain circumstances
* Payment for water services can also be one important way of helping negotiations with people living in or using watersheds to develop land-use mosaics that are conducive to maintaining high quality drinking water supplies
 
2. World's biggest cities, drinking water and protected areas

The report includes a study of world's top 105 cities (25 each from Africa, Americas, Asia, Europe, and 5 from Australia) demonstrating the global importance of forests to urban water supplies. A summary of the findings from the study is provided below. The report offers information on the cities that rely on protected areas for their drinking water supply and the measures some of them have taken for sustainable provision of their water supply requirements.

Many of the world's largest citites rely on drinking water from protected areas:

* Around a third (33 out of 105) of the world's largest cities obtain a significant proportion of their drinking water directly from protected areas
* At least five other cities obtain water from sources that originate in distant watersheds that also include protected areas
* In addition, at least eight more obtain water from forests that are managed in a way that gives priority to their functions in providing water
* Several other cities are currently suffering problems in water supply because of problems in watersheds, or draw water from forests that are being considered for protection because of their values to water supply
 
3. A wider perspective on water and protection
 
Running Pure report also includes essays, written by specialists, on three key aspects in the use of forest protection for urban water supply. The three aspects are:

Hydrology Overview

Written by Professor Lawrence S Hamilton and David Cassells, this essay explains the role of forests in watersheds and catchments, the type of forests most suitable for regular water supply to urban areas, and the conditions in which these forests can help in preventing erosion, sedimentation and floods.

Economic Overview

In this essay, Stefano Pagiola (Senior Environmental Economist, World Bank), makes a case for payment for watershed services through Payment of Environment Services schemes. The essay gives an economic overview that covers the logical basis for such payments, what is required to arrive at valuations of watershed services, the actors involved and what they need to consider for making such payment systems successful.

Social Overview

Designation of lands and waterways for urban watershed protection can have widely varying impacts on different groups because the livelihoods and welfare of low-income groups in developing countries are especially sensitive to access to water, forest and land. This essay, by Sara J. Scherr (Director, Ecosystem Services, Forest Trends), focuses on potential social implications of protecting and managing forests for water supply on such groups.