Scope of the assessment
This study analyzes quantitative and qualitative information and develops selected indicators of the condition of the world’s freshwater systems. The condition is defined as the current and future capacity of the systems to continue providing the full range of goods and services needed or valued by humans.
Where available, we use global data sets to illustrate key indicators. In cases in which global data are not available, we use regional- and national-level information to illustrate important concepts, indicators, trends, and issues. Sometimes, local-level case studies have been used to illustrate trends that appear to be important but for which national or global data do not exist.
On a global scale, only limited information is available on the condition of the world’s freshwater systems. Often the spatial resolution and temporal domains for different parts of the world are poorly harmonized. Most developing countries lack environmental monitoring programs for freshwater systems. Even developed countries with data-collection systems on hydrology, species, habitats, and physical and chemical parameters of water quality have done little to develop indicators that measure important ecological processes of freshwater systems, such as water purification and aquifer recharge. More also needs to be done to integrate data for entire watersheds, from water supply and consumption to land use and biodiversity.
Our analysis looks at measures that show the degree of human intervention in the hydrological cycle and what we know concerning three important goods and services provided by freshwater systems: water, food, and biodiversity. These goods and services were chosen partly on the advice of a wide range of freshwater experts and partly because of data availability. The data and indicators presented in this pilot analysis focus on the following:
- Human modification of freshwater systems. (These include all physical changes in the hydrological cycle, especially river and stream corrections, flood control by dams, conversion of wetlands, and land-use changes in the entire watershed—all of which are changing runoff characteristics).
- Water quantity (i.e., availability).
- Water quality.
- Food (fish in particular).
- Biodiversity.
We use these indicators to identify existing data, highlight characteristics of ideal indicators to measure the capacity of freshwater ecosystems, and point out data and information needs. These in turn will become useful inputs for the Millennium Ecosystem Assessment.
Even though food production from irrigated crops is intimately related to water availability, and agriculture is the biggest user of water, this report does not assess the condition of freshwater systems for agriculture production. A separate Pilot Analysis of Global Ecosystems (PAGE) report on agroecosystems assesses agriculture production in detail. Moreover, this report on freshwater systems does not cover additional important services derived from freshwater systems such as hydropower, transportation, and recreation.
Hydropower electricity production plays a significant role in the overall energy output of many countries. Of the total electricity generated in the world, hydropower accounts for 18 percent and in 18 countries, including Brazil, Norway, Burundi, and Laos, it generates 90 percent or more of the electricity (Gleick 1998:276–280).
Since historical times, transportation has been a crucial service that humans have derived from freshwater systems. Rivers have been harnessed as routes for exploring, colonizing, and settling new areas, as well as transporting goods and communicating. In western Europe, for example, inland waterways transport almost 8 percent of all inland freight (EEA 1995:441).
Tourism and recreation, as well as the more subtle spiritual and aesthetic qualities of freshwater systems, constitute perhaps the most important omission from this study. Society places a high value on freshwater recreational activities, such as boating, fishing, hunting, birdwatching, and swimming. These services generate billions of dollars in direct and indirect revenue in many developed and developing countries. Exact figures are hard to calculate because of the dispersed nature of these activities. In the United States alone, however, 30 million anglers went freshwater fishing in 1996, expending US$24.5 billion on trips and equipment (UFWS 1996:8).
The spiritual and aesthetic qualities of freshwater systems cannot readily be captured by the kind of quantitative analysis presented here. For two reasons, this study does not consider data on tourism revenues, which some analysts have used as proxy measures of human appreciation. First, the very concept of analyzing freshwater systems goods and services is essentially utilitarian, whereas emotional commitment to these systems as things of beauty or intrinsic value is essentially normative. Second, any attempt to develop quantitative indicators of such intangible issues risks removing them from their proper arena of political, moral, and cultural debate.
Finally, even though groundwater resources play a critical role in many regions of the world by providing potable, industrial, and irrigation water, global data on this resource are scarce and dispersed among national agencies. This analysis, therefore, provides a general overview of the issues affecting groundwater resources and their condition.
Conclusions
Human activities have severely affected the condition of freshwater systems worldwide. Even though humans have increased the amount of water available for use with dams and reservoirs, more than 40 percent of the world’s population lives in conditions of water stress. This percentage is estimated to grow to almost 50 percent by 2025. Surface and groundwater is being degraded in almost all regions of the world by intensive agriculture and rapid urbanization, aggravating the water scarcity problem. In addition, lack of access to clean water continues to be a leading cause of illness and death in much of the developing world. Food production from wild fisheries has been affected by habitat degradation, overexploitation, and pollution to a point where most of these resources are not sustainable without fishery enhancements. Finally, the capacity of freshwater ecosystems to support biodiversity is highly degraded at a global level, with many freshwater species facing rapid population declines or extinction.
The PAGE study relied on existing global and regional data collected by organizations and scientists around the world. Without their efforts and their willingness to share the data, this study would not have been possible. We found many detailed data sets at the national level, particularly for the United States. However, at the global level, data on freshwater resources are scarce. Basic statistics on water availability and use, for example, are not readily available or are available only at the national level. This makes an assessment of freshwater systems difficult because the ideal biophysical unit of analysis is the watershed – which often crosses national boundaries.
Improved national and global data on ecosystem land use characteristics, basic hydrological information, fisheries production, and freshwater species could lead to significantly more knowledge about the condition of freshwater systems. Better information on actual stream and river discharge, and the amount of water withdrawn and consumed, would increase our ability to manage freshwater systems more efficiently and evaluate trade-offs. But much effort and financial commitment would have to be made to restore many of the hydrological stations around the world, which have been declining since the mid-1980s and, in some cases, are no longer functioning.
Remotely sensed data from new satellites with higher quality sensors and much larger onboard storage capacity will allow better analysis of the changes in land-use patterns, and may allow for a complete and accurate mapping of the extent of both seasonal and permanent wetlands. With this information, resource managers would be able to use existing models to better understand how watershed changes are likely to affect the water quantity, and quality, of rivers and lakes.
In terms of food production from inland waters, there is an urgent need to improve the quality of the data on inland capture fisheries and those environmental and socioeconomic factors that affect their sustainability. Improved inland fishery data are likely to require improved or new monitoring networks, which means a financial commitment to strengthen both national fisheries departments and collaborating organizations, such as the Food and Agriculture Organization of the United Nations.
In terms of food production from inland waters, there is an urgent need to improve the quality of the data on inland capture fisheries and those environmental and socioeconomic factors that affect their sustainability. Improved inland fishery data are likorks that are beyond the reach of many developing countries. Even though surface water monitoring programs are well developed in most Organization for Economic Cooperation and Development (OECD) countries, water quality monitoring in most parts of the world is rudimentary or nonexistent. Even those developed countries that have water quality monitoring programs in place focus on chemical parameters that leave out important biological information. One of the biggest challenges in future water monitoring programs is the integration of chemical and biological measures of water quality.
If surface water monitoring is still deficient in many countries, the situation for groundwater is worse. Many nations lack proper monitoring of groundwater recharge quality. Information on groundwater quality, as well as on aquifer storage capacity and exploitation, is urgently needed. Currently there are two proposed initiatives that could help fill in the information gap on groundwater resources as well as promote their sound management. The first is a high-level Groundwater Management Advisory Team, coordinated by the World Bank and the Global Water Partnership. The aim of this team is to promote more effective management of groundwater resources around the world, through improved understanding of the hydrogeological constraints and strengthening of the institutional framework. The second is an International Groundwater Resources Assessment Center, that will collect data on and monitor groundwater worldwide. This initiative is being coordinated by UNESCO and the World Meteorological Organization.
Finally, as this study will stress, information on freshwater biodiversity is poor even in those developed nations that have considerable financial and technical resources. There are several new international initiatives, including the OECD’s Global Biodiversity Information Facility (GBIF) and the Global Taxonomy Initiative of the Convention on Biological Diversity that will help identify and catalogue species around the world. This knowledge and monitoring would allow for a more complete assessment of the condition of freshwater systems.
Recommendations for the Millennium Ecosystem Assessment include the following:
- Compiling more complete information on the precise location of the world’s dams, including the thousands of dams less than 15 meters in height that are not currently listed in international databanks.
- Developing a complete global spatial data set on wetlands distribution. Information on the location and size of wetlands is especially needed for Asia, Africa, South America, and Oceania.
- Promoting the restoration of the hydrological monitoring stations and improving the water supply and use statistics at the watershed level.
- Compiling a global data set on groundwater resources, including their distribution, capacity, and use.
- Encouraging national governments to establish water quality monitoring programs that combine chemical and biological measures for both surface and groundwater.
- Strengthening the role of national fisheries departments in data collection for inland fisheries resources.
- Establishing a systematic data collection effort on the contributions of fish stocking, introduction, and other enhancement programs to inland fisheries.
- Monitoring key indicator species for freshwater systems, as well as monitoring the presence or introduction of nonnative species and their impacts on native fauna and flora.
