撒哈拉以南非洲城市水资源规划（英文版）.pdf

Sub-Saharan Africas Urban W ater Blueprint SECURING WATER THROUGH WATER FUNDS AND OTHER INVESTMENTS IN ECOLOGICAL INFRASTRUCTURE AUGUST 2016Cover photo credits from top left: Nick Hall, Georgina Smith/CIAT, Nick Hall, Africanmoose/Shutterstock, John Wollwerth. Inside front cover and page 2: Georgina Smith/CIAT. Lead authors Colin Apse and Nathan Karres Contributing authors Misty Herrin, Frederick Kihara, Daniel Shemie, Margaret Southern and Cory Zyla Editor Sonja Mitchell, Yellowbrick Marketing Designer Jeff Walker Acknowledgements Special thanks to TNC staff who provided review and other support, including: Timm Kroeger, Robert McDonald and Kari Vigerstol Recommended citation TNC, 2016. Sub-Saharan Africas Urban Water Blueprint: Securing Water Through Water Funds and Other Investments in Ecological Infrastructure. The Nature Conservancy: Nairobi, Kenya. Updated information and interactive maps nature/africa-water1 SECURING WATER THROUGH WATER FUNDS AND OTHER INVESTMENTS IN ECOLOGICAL INFRASTRUCTURE Executive summary Africas urban population is expected to double over the next 20 years, posing an immense water challenge for cities. Growing demand from a booming population and continued economic growth will further stress already scarce water resources. Many cities source their water from rural landscapes which are increasingly affected by unplanned development and poor land management practices. A citys water security is at risk if the health of its watershed degrades. Unhealthy watersheds can contribute to pollution in rivers, lakes and reservoirs, potentially reducing water supply availability and increasing delivery costs. Nature is also under threat, as aquatic life suffers from lower water quality and drying rivers while wildlife loses critical habitats and food supply. It is imperative that African cities and businesses become wise stewards of the land where their water comes from to ensure a sustainable and affordable supply of water. In this report we investigate the status of Sub-Saharan Africas urban water sources and the potential for catchment protection to benefit cities, rural livelihoods and nature. Protecting water catchment areas is a smart investment opportunity for government, civil society and business leaders across Africa. Beyond improved urban water security, nature-based solutions provide multiple benefits for people and nature, such as reducing flood risk. Identifying priority watersheds Three-quarters of large cities in Sub-Saharan Africa source at least half of their public water supply from surface water sources, amounting to an estimated 3.5 billion cubic meters annually. In this report, authors from The Nature Conservancy identify 30 cities primarily dependent on surface water supply that have the potential to significantly benefit from watershed conservation practices. Land use change is a key factor affecting the health of all their watersheds. These 30 cities source water from 84 catchments accounting for more than 67 million hectares an area 26 times larger than their urban footprint. On average across these cities, 38 percent of catchment areas have been developed for agriculture with potential impacts on water quality for downstream users. Water sources at risk Understanding the condition of catchments is important for cities and other water users. Catchment land development while not wholly predictive of water quality impairment is a major factor in water security. One-fifth of source catchments assessed may be impacted by degraded water quality often the result of increased soil erosion and high nutrient loads from excessive fertilizer use. In cities primarily dependent on surface water supply, one in every five residents (more than 17 million people) may face water security risks due to highly impaired water quality. Ongoing catchment degradation comes at significant financial cost every year. For example, in the Upper Tana River catchments that serve the water supply system of Nairobi, Kenya, water treatment costs have been estimated to increase by more than 30 percent following heavy storms due to high sediment loads. Likewise, a proposed hydropower project on the Ruzizi River, located between Lake Kivu and Lake Tanganyika and shared by Rwanda and the Democratic Republic of Congo, estimates a 10 percent decrease in power generation capacity as a result of sedimentation from cultivation on steep slopes. Land use change has an equally damaging impact on nature, including fisheries. Some 5.8 million hectares of priority biodiversity areas are potentially at risk within the identified source catchments which face the greatest development pressure. Catchment conservation potential In this report we estimate the potential for conservation actions forest protection, reforestation, riparian restoration and agricultural best management practices (BMPs) to reduce sediment and nutrient loads. We identify 28 cities that can achieve appreciable reductions in sediment or nutrients through such conservation activities. For 16 of these cities, avoided treatment costs could offset at least 25 percent of total conservation costs. Half could potentially offset the entire cost of catchment conservation through avoided treatment costs alone (where treatment savings exceed conservation costs). Implementing agricultural best management BMPs, such as the use of terraces and cover crops, has the broadest applicability across our sample of cities, potentially improving water quality for 85 million people. Forest protection and restoration while spatially more limited in applicability as compared to agricultural BMPs could achieve reductions in pollution that would benefit up to 52 and 11 million people, respectively. Importantly, the benefits of catchment protection also extend outside city boundaries by supporting the protection of landscapes important for wildlife and rural communities. We identify 13 cities where conservation practices can achieve pollution reduction and protect wildlife habitat in priority conservation areas. For seven of these cities, water treatment savings could offset at least a quarter of conservation costs. We highlight the potential for catchment protection to have far-ranging benefits beyond water quality and biodiversity for these and other cities in Sub-Saharan Africa. A path forward The implementation of programs to support catchment conservation has been slow to develop, despite their significant potential to achieve multiple benefits for people and nature. The most recent survey identified just eight operational programs in Sub-Saharan Africa. Limited local governance capacity and insufficient investors are some of the primary barriers to implementation.2 SUB-SAHARAN AFRICAS URBAN WATER BLUEPRINT Overcoming these challenges requires a mechanism for collective action and sustainable financing. A proven model water funds presents city leaders with a platform to achieve sustainable catchment conservation at scale and to provide significant returns to both people and nature. Water funds bring together diverse water users from the public and private sector to jointly invest in targeted, scientifically guided conservation interventions to protect the water resources they rely on. The Nature Conservancys first water fund was established in Quito, Ecuador, in the year 2000. Today, the Conservancy is involved in more than 60 water funds, both in operation and in the planning phase, across four continents. Water funds have proven to be an effective tool for unlocking new sources of funding previously unavailable to cities by providing water users and public funders with a stable and transparent means to proactively invest in the long-term health of catchments. Our sample of the largest cities in Sub-Saharan Africa represents only a fraction of the regions overall potential for source catchment conservation. The Nature Conservancy is committed to the rapid advancement of water funds in priority cities that are in urgent need of improved water security and biodiversity protection. We are seeking to create a coalition of partners from the private sector, government and civil society that are interested in working together to harness the enormous potential of this proven model. Water funds offer the promise of a transformative and lasting approach through innovative finance and governance to secure the health and productivity of water sources that are fundamental to sustainable growth and prosperity. 3 SECURING WATER THROUGH WATER FUNDS AND OTHER INVESTMENTS IN ECOLOGICAL INFRASTRUCTURE Introduction: protecting water for people and nature Overview For many cities, source catchments the land surrounding rivers and lakes where water runoff is captured are critical to water security. 1In healthy catchments, forests, grasslands and well-managed agricultural areas help ensure the availability of clean and sufficient drinking water. In this way, “natural infrastructure” or “ecological infrastructure” is essential for sustaining the livelihoods and well-being of city dwellers. Cities face significant threats to their water sources where source catchments have been impacted by poorly managed land development. Increased sediment often pollutes rivers and lakes as catchment health degrades and can potentially reduce water availability during drought. 2,3This pollution results in greater water insecurity, making it more difficult and more expensive to provide clean water to urban residents. The prospects of increasing urbanization where 50 percent of Africans will live in cities by 2030 combined with the implications of changing climate, will further exacerbate this water insecurity. 4,5 In this working paper, we describe the potential for catchment protection to support improved management of water resources for cities. Cities can reduce water supply costs and uncertainty by investing in catchments that protect water resources before they reach the pipes and reservoirs that cities depend on. Importantly, the benefits of catchment protection also extend outside city boundaries by supporting improved livelihoods and well-being for those living within source catchments, and conserving landscapes to protect fish and wildlife. 6Beyond describing the value of catchment protection, we propose a model for cities to realize this potential. Water funds establish a governance and financial mechanism that permits public and private water users to fund and implement catchment protection. This study provides the foundations through technical analysis of catchment protection potential and documenting the success of the water funds approach to enable African leaders from government, business and civil society to leverage the potential of catchment areas to benefit both people and nature. Approach The Nature Conservancy has previously mapped the global potential for addressing the growing urban water challenge through nature-based strategies. 1The Urban Water Blueprint focused primarily on the worlds 100 largest cities and found that more than 700 million people globally could benefit from improved water security from catchment conservation. Here, we build from this analysis in three significant ways:z We focus our perspective on Sub-Saharan Africa (SSA), constructing a roadmap for source catchment conservation that leverages the Conservancys growing program in SSA focused on collaborating with government, the private sector and other NGOs on conservation solutions. z The potential benefits of catchment conservation extend beyond urban water security alone. This analysis emphasizes another dimension critical to our mission: the potential benefits for natural areas and wildlife.z While the Conservancys global report highlighted great potential to mitigate sediment and nutrient pollution one in every four cities could realize cost savings from catchment conservation it did not provide a definitive mechanism for implementation. Water funds are proposed here as an evidence-based approach for achieving catchment protection at scale. Water funds Urban source catchments are not only critical for cities water supply, but also for rural communities and nature. As a result, catchment conservation represents unique opportunities to achieve multiple benefits for many different stakeholder groups. 1Effective conservation efforts require the coordination of these different stakeholders. In its absence, conservation funding is often inadequate, efforts may be duplicated, and efficiencies are lost, posing a significant risk to both upstream and downstream users. 7 Figure 1. Water funds model Conceptual diagram of water funds model. Figure excerpted from Forest Trends, “Gaining Depth: State of Watershed Investment 2014” . 8 Water funds provide a solution whereby downstream water users directly or indirectly compensate upstream parties for activities that deliver water benefits to the payer (Figure 1). From South America to East Africa, there is growing precedent for beneficiaries from the public and private sector to invest jointly in a water fund. The water fund establishes a financial and governance mechanism to direct funding toward targeted, scientifically guided investments in catchment protection. Investors can pool resources sufficient for achieving results at scale by investing collectively. Such an institutional 4 SUB-SAHARAN AFRICAS URBAN WATER BLUEPRINT arrangement also serves an important governance function, providing a forum for evidence-based collective planning and decision-making while also giving investors and rural communities a voice in how water catchments are managed. The Nature Conservancy is currently involved in more than 60 of these water funds, where public and private water users come together, often alongside local government, to invest collectively in conservation of the catchments that provide their sources of water supply. A third of these water funds are already in full operation, mostly in Latin America, but the model is now spreading across four continents. Once an opportunity is identified, a growing body of research and tools now exist to help water users decide where in the catchment to invest. Where cities source their water Through a recent effort completed by the Conservancy, we surveyed the drinking water sources such as surface streams, groundwater wells and desalination plants for more than 500 cities across the world, including the 30 cities in SSA assessed here. 1We were further able to estimate the amount or volume of withdrawals attributable to these different water source types for many of these cities. Where prior efforts have considered water resource risks relative to a citys location, t