Nature-Based Solutions for Water - Part Two
Nature-Based Solutions for Water Scarcity
TITLE: The United Nations World Water Development Report 2018: Nature-Based Solutions For Water Scarcity
CORPORATE AUTHOR: UNESCO World Water Assessment Programme
COPYRIGHT LICENSE TYPE: CCBY-SA 3.0 IGO. The text was edited for readability.
As the fifth in a series of annual, theme-oriented reports, the 2018 edition of the United Nations World Development Report (WWDR) focuses on opportunities to harness the natural processes that regulate various elements of the water cycle, which have become collectively known as nature-based solutions (NBS) for water. Maximizing nature’s potential can help to achieve the three main water management objectives – enhancing water availability, improving water quality and reducing water-related risks.
The global demand for water has been increasing at a rate of about 1% per year as a function of population growth, economic development, and changing consumption patterns, among other factors, and it will continue to grow significantly over the next two decades. Industrial and domestic demand for water will increase much faster than agricultural demand, although agriculture will remain the largest overall user. The vast majority of the growing demand for water will occur in countries with developing or emerging economies.
At the same time, the global water cycle is intensifying due to climate change, with wetter regions generally becoming wetter and drier regions becoming even drier. At present, an estimated 3.6 billion people (nearly half the global population) live in areas that are potentially water-scarce at least one month per year, and this population could increase to some 4.8–5.7 billion by 2050.
Nature-based solutions mainly address water supply through managing precipitation; humidity; and water storage, infiltration and transmission, so that improvements are made in the location, timing and quantity of water available for human needs.
The option of building more reservoirs is increasingly limited by silting, decrease of available runoff, environmental concerns and restrictions, and the fact that in many developed countries the most cost-effective and viable sites have already been used. In many cases, more ecosystem-friendly forms of water storage, such as natural wetlands, improvements in soil moisture, and more efficient recharge of groundwater, could be more sustainable and cost-effective than traditional grey infrastructure such as dams.
Agriculture will need to meet projected increases in food demand by improving its resource use efficiency while simultaneously reducing its external footprint, and water is central to this need. A cornerstone of recognized solutions is the ‘sustainable ecological intensification’ of food production, which enhances ecosystem services in agricultural landscapes, for example through improved soil and vegetation management. ‘Conservation agriculture’, which incorporates practices aimed at minimizing soil disturbance, maintaining soil cover, and regularizing crop rotation, is a flagship example approach to sustainable production intensification. Agricultural systems that rehabilitate or conserve ecosystem services can be as productive as intensive, high-input systems, but with significantly reduced externalities. Although NBS offer significant gains in irrigation, the main opportunities to increase productivity are in rainfed systems that account for the bulk of current production and family farming. These opportunities also provide livelihood and poverty reduction benefits. The theoretical gains that could be achievable at a global scale exceed the projected increases in global demand for water, thereby potentially reducing conflicts among competing uses.
NBS for addressing water availability in urban settlements are also of great importance, given that the majority of the world’s population is now living in cities. Urban green infrastructure, including green buildings, is an emerging phenomenon that is establishing new benchmarks and technical standards that embrace many NBS. Business and industry are also increasingly promoting NBS to improve water security for their operations, prompted by a compelling business case.