Mieczysław S. Ostojski, PhD., Eng. firstname.lastname@example.org
Jerzy Niedbała, MSc., Eng. email@example.com
Paulina Orlińska, MSc., Eng. firstname.lastname@example.org
Paweł Wilk, MSc., Eng. email@example.com
Joanna Wróbel, MSc., Eng. firstname.lastname@example.org
Richard A. Kidd, MSc. email@example.com
Water on Earth is an irreplaceable commodity. Improper selection of indicators of water resources can lead to underestimation or overestimation of water. Incorrect assessment of water resources contributes to an improper fulfillment of water management tasks, including addressing the needs of different types of water users, including, inter alia, population and the economy (industry, agriculture and forestry, hydropower, inland navigation, tourism and recreation).
The paper discusses the benefits of using Earth observation technology in the Global Monitoring for Environment and Security (GMES) program for estimating water resources in Poland. The authors conclude that a summary of the total amount of water resources in different components, including the availability of water for people, will allow for proper assessment of water resources.
Despite the vast amount of water on the planet, decades of unsustainable water management have caused that water shortages have reached a crisis point in many regions. Globally more than 50 percent of all renewable and accessible freshwater resources are used but billions still lack the most basic water services. As a result of prolonged periods of low rainfall or drought, the balance between water demand and availability has reached a critical level in many areas of Europe. Both water and population are unevenly distributed in Europe, and therefore countries and subregions experience varying degrees of water stress. The average annual precipitation in Europe for the period of 1940–1995 is presented in Figure 1.
Water availability problems occur when the demand for water exceeds the amount available during a certain period. Difficulties occur frequently in areas with low rainfall and high population density, and in areas with intensive agricultural or industrial activity. Apart from water supply issues, overexploitation of water has led to the drying out of natural areas in western and southern Europe and saltwater intrusion in aquifers (EEA 2008).
The possibility of water supply is characterized by the indicator of water availability. It is the quotient of the average annual water runoff by rivers into the sea from the specific area divided by the number of people inhabiting the area. About 44,000 cubic kilometers of water flows into the sea from rivers throughout the world. Assuming the current state of the population on Earth equal to 7 billion, we receive an average water availability of 7,000 cubic meters per capita per year (Gleick, 2005). This is the amount of water which is completely sufficient to cover all municipal, industrial, agricultural or recreational water needs. Unfortunately, water resources are characterized by very unequal distribution in time and space.
There are countries, where the indicator of water availability exceeds several thousand cubic meters per capita per year. Naturally, there are countries characterized by significantly fewer capabilities. The useable water supply is reduced by the fact that the bulk of water flows by river during floods, and that a considerable amount of water is polluted and not suitable for any purpose. Drinking water resources in Europe are presented in Figure 2.
II. WATER RESOURCES AND WATER NEEDS IN POLAND
According to the principle of sustainable development (in terms of protecting water resources and water management), water use depends on the state of water resources of the country. In addition, water resources are understood as the general surface and groundwater volume occurring permanently or temporarily in a particular area. The volume and quality of these resources determine the economic development of societies and have an impact on the quality of life. Water resources are used from different sources including surface water, groundwater, precipitation or post-production water. The same water can be repeatedly used (power industry). Surface water, groundwater and rainwater resources are usually characterized by an uneven distribution. The reasons for this variation are topographical, geological and meteorological characteristics and various types of land use (Figure 3). In addition to their spatial variability, surface water and rainfall are characterized by a random variability in time, conditioned by meteorological phenomena. The annual cycle of these phenomena determines the average annual variation, both in the long term and within individual years. Renewability of water resources depends on, inter alia, the amount and intensity of precipitation, as well as on terrain, soil and other factors, all of which affect the volume of surface and soil runoff.
The water balance of a country includes: precipitation (P), evapotranspiration (E) and river runoff (H) at the surface (H’) and underground (H”). The individual components constitute a general equation of water balance:
P= (H’+H”) + E
According to the above equation, the total water resources are defined as the subtraction of precipitation and total evaporation, terrain and river runoff. Figure 4 shows the total volume of water resources in selected European countries in comparison with the surface of the country. It may be noted that the size of the country’s area is directly proportional to the water volume.
Considering the amount of total resources, in accordance with the presented data, Poland is on 19th place among 29 countries analyzed, and by precipitation in 11th place, following Austria, Switzerland, Ireland, Bulgaria and Romania. In terms of external flow, Poland is estimated to be at 17th place among 29 countries. Figure 5 presents a summary of total water resources and total consumption volume area per km2.
The analysis of water amount in hm3 per unit area in km2 shows water resources in the country. Thus, the presented data enable an overview and comparison of the countries in terms of availability of surface water resources. The results show Poland as a country with relatively low water resources, as proved by this study. From the point of view of water use for the national economy, there is a distinction between water consumers (sectors of the national economy consuming water for production purposes) and water users (sectors of the national economy using water, but not consuming it). Consumers of water are heat and power industries, municipal economy, agriculture and forestry (sectors). Water users are hydropower, navigation, tourism and recreation. In Poland, the biggest water consumption is by electric energy production associated with coal energy (cooling processes). At present, Poland has very low water consumption in agriculture, approximately half that of Western European countries where a large portion of water consumption is spent on irrigation, which in Poland is not required on such scale due to weather conditions (Wprost, 2011). The structure of water consumption in the major sectors of the national economy in comparison with other countries according to Food and Agriculture Organization (FAO) is presented in Figure 6.
Problems with water supply in Poland may also occur in a situation where agriculture, as in other Western European countries, will collect more water for irrigation than at present. But expectations in the coming years are that Poland is not threatened by a water crisis. There is a risk, however, that water resources may be unevenly distributed – some regions may experience severe water shortages and some an excess.
III. ESTIMATION OF WATER RESOURCES IN POLAND
Analysis of the size of groundwater resources within the catchment requires knowledge of the conditions and possibilities of their discharge and renewal within each hydrogeological unit. Groundwater resources are divided into static and dynamic. Static resources are below the long-term and seasonal fluctuations of groundwater and this is gravitational water, filling the utility levels below the lower limit of seasonal and perennial groundwater fluctuations. It can be either renewable (which is in hydraulic contact with the surface area) or non-renewable (isolated from the surface of the terrain and other aquifers). A correct assessment of deep groundwater resources involves careful evaluation. This information can change the opinion of the size of water resources in Poland (Mikulski, 1998).
Consumable surface water resources are difficult to estimate because of the possibility of their reuse. International data bases of these resources are limited or incomplete and most importantly they vary in many aspects. There are no homogeneous and comparable data for long time periods that could be the meaningful bases for more thorough analysis. Water resources of the country are usually measured by volume of water produced in a specific area in a defined period of time as a result of atmospheric processes (Kaczmarek, 1978). The analysis of Polish water resources must take into account the amount of precipitation, river water supply, lakes and aquifers and the above-mentioned factors affecting the size of the disposable and consumable resources. Despite the relatively small resources, a water deficit in Poland does not result from the lack of water in general, but a lack of water in the right place and of adequate quality.
Nowadays, more frequent droughts will become a major concern for the country’s economy. Moreover, increased demand for water is forecasted.
The values characterizing water resources are continuously changing as a result of a set of water characteristics that distinguish it from other natural resources of the globe. The quantity of water resources depends on varying amounts of rainfall over time and on the physiographic conditions of the country. In the process of water resource use, only a small part of the resources (except the great consumption of water for evaporation) does not return to circulation, conventionally defined as the nonrefundable loss. Most of the water collected for different purposes goes back into circulation and is usually partially polluted.
IV. THE CONSEQUENCES OF POOR WATER RESOURCE ASSESSMENT
Poland has a high rate of water consumption (FAO, 2011). Water per capita per year is probably the best synthetic indicator because it illustrates the richness of water for each country, but despite its advantages, it is not convincing. For an average citizen, this hypothetical amount remaining at their disposal usually exceeds their need by several times but for planners and strategists this indicator does not show the direct action that should be taken. Water management strategies need a more detailed analysis related to the extreme periods, types of demand or averaging capacity of reservoir discharges. Improper selection of indicators of water resources can lead to underestimation or overestimation of water. This can result in the mismanagement of water in the country, having negative impacts on water allocation for different sectors of the economy. Incorrect estimation of water resources contributes to the improper realization of water management tasks, including addressing the needs of different types of water users, including, inter alia, population and the economy (industry, agriculture and forestry, hydropower, inland navigation, tourism and recreation). For nonconsumers, such as hydropower and tourism, incorrect estimates are not as significant as for consumers, like public utilities, agriculture and industry, for which the consequences are sometimes serious limitations in meeting their needs. Relative needs, which are replaceable, can be met by substitution solutions, while the absolute water needs cannot be replaced in any way. Incorrect estimation of resources may also have direct or indirect impacts on water prices, which can lead to a significant increase of economic costs. All the above-mentioned factors tend to suggest changing the approach to estimation of water resources in Poland, thus changing the presentation and interpretation of the analytical results. Such a change should also affect the interpretation of the collected data and improve the opportunities for their utilization.
V. THE USE OF EARTH OBSERVATION SYSTEMS FOR THE PROPER ASSESSMENT OF WATER RESOURCES
Space images of the Earth provide a wide range of information that may be impossible or difficult to obtain using ground-based systems. Applications of these images are rapidly increasing – from geodesy, cartography, oceanography, forestry or marine science to the study of climate change – as are attempts to respond in advance to the threat of natural disasters and the assessment and effective management of their effects. The information obtained from satellite imagery can also be used to assess water resources. Remote sensing is a system of collecting information about objects and phenomena without direct contact with the sensor. Different methods of collecting information provide data that have complementary properties to each other. For example, airborne images are characterized by higher resolution and flexibility of implementation of data capture campaigns, while satellite systems have the potential to capture data at a global scale.
Information derived from satellite systems is important in the meteorological and water management measurements due to the large swath extent of the imagery, which allows wide-scale observation and can be combined with simultaneous measurements. Another advantage for meteorology is the opportunity to obtain current information with the possibility of frequent and fast updates. Data analysis provides, inter alia, the possibility of obtaining detailed data for monitoring drought nationwide. Remote sensing has a very wide range of applications. For resources and water management these applications include meteorological observations and weather forecasting; analyzing changes in the environment to assess changes in climate processes, global warming and the impact of human activity; estimation of losses in reservoirs due to drought, floods and biological contamination; information for water cadastre; determination of the biological conditions of the aquatic environment; and the designation of areas exposed to flood hazards (Ryzenko, 2007).
The Global Earth Observation System of Systems (GEOSS), coordinated by the Group on Earth Observations (GEO) actively coordinates activities across societal benefits areas (SBAs) aiming to achieve a harmonized system on land, sea and air-space and to provide comprehensive data, information and analysis on the environment. Data and information in the nine SBAs provided by GEOSS are groups of complex issues that require accurate data on the spatial and temporal resolution. The main aims for these groups are (European Commission, 2011):
• Minimizing loss of life and property due to natural disasters and disasters caused by man
• Understanding the environmental factors affecting human health and well-being
• Improving management of energy resources
• Understanding impact assessment, mitigation and adaptation to climate change
• Improving management of water resources through a more detailed analysis of the water cycle
• Improving the quality of weather information, forecasting and warning systems
• Improving management and protection of terrestrial, marine and coastal areas
• Promoting sustainable agriculture and combating desertification
• Understanding, monitoring and conservation of biological diversity.
The Global Monitoring for Environment and Security program is being supported within the framework of GEOSS. The program aims to provide information about the Earth’s surface to maintain environmental sustainability. Subjects include the GMES environmental monitoring of the oceans and atmosphere, the Earth’s surface including crop forecasting, development of vegetation, providing an early warning system and the use of water resources for the sustainable management of these elements. Another advantage is integrating Earth observation data for GMES by products intended to support implementation of policy and European directives. The products allow the supply of information, dissemination and implementation of the Convention and integration models to prepare them for operational use (European Commission, 2011).
Pre-validation of GMES Global Service for Water Scarcity Information is conducted by the GLOWASIS project. It will be a portal providing water scarcity information by securing access to the monitoring data from satellites and in situ sensors, with improved forecasting models with improved monitoring data and linked statistical water data in forecasting. It also aims to promote GMES Services and European satellite utilization.
Earth observation technology allows examination of various factors in considering the observations of water resources and acquisition of information on their size. Satellite meteorological observations have great importance for estimating water resources. In discussing meteorological processes in the atmosphere with their varying spatial and temporal dynamics, attention should be paid to various possibilities of Earth observation technologies to provide information. The requirements of a particular analysis depend on the scale of meteorological phenomena, their dynamics, the possibility of classification and physical parameters. Imaging allows acquisition of information about fast-changing as well as slow-changing phenomena, their mutual correlation and relationship (Struzik, 2008). In addition, the study of water resources in the soil layers is important when assessing a drought. In Poland, due to scarce data and the local character, this assessment is currently difficult. Satellite observation gives wide opportunities for estimating water resources in a global, holistic and detailed way at a reliable scale (Usowicz, 2009).
Potential water deficit in Poland results not from the lack of water in general, but from the lack of water in the right place and of adequate quality. Reservoirs in Poland with a total capacity of about 4 billion m3 equal approximately to 6.5 percent of average annual runoff volume do not provide the full protection against floods and drought, and do not guarantee adequate water supply. Estimation of water resources in Poland turns out to be a complex process. Correct determination of water resources is very important in reference to water needs in Poland. Incorrect estimation of the amount of water in Poland led to the improper planning of water use. The consequence of this is the inadequate management of water resources. New research, analysis and technologies enable precise measurements of the amount of water circulating in the atmosphere, pedosphere, biosphere and hydrosphere. A summary of the cumulative volume of water resources in the various components, including the availability of water for the human use, will allow proper assessment of water resources in Poland. Such measurements are possible thanks to the utilization of Earth observation technologies. These systems provide a global, accurate, comparable and reliable measurement of water resources, and will enable the determination of the amount of water in Poland. Moreover it will show the real water quantity in Poland compared to other countries of the world.
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This work has been supported by the GLOWASIS project, a collaborative project aimed at pre-validation of a GMES Global Water Scarcity Information Service, and funded within the EU Seventh Framework Programme by the grant agreement 26225 under the call FP7-SPACE-2010.1.1-04.
Mieczyslaw Ostojski is director general of the Institute of Meteorology and Water Management in Poland. He has been closely involved in the activities of the World Meteorological Organization. His current activity is mainly focused on coupling meteorological and hydrological models to advance knowledge in flood forecasting and help build capacities in Flood Risk Assessment.