Integrated Management of Source Water Quantity and Quality for Human Health in a Changing World

Integrated Management of Source Water Quantity and Quality for Human Health in a Changing World F Sun, M Chen, and J Chen, Tsinghua University, Beijing, China & 2011 Elsevier B.V. All rights reserved.

Abbreviations IPCC

Intergovernmental Panel on Climate Change Integrated Water Resources Management polycyclic aromatic hydrocarbons river basin districts river basin management river basin management plans Source Water Assessment and Protection total annual renewable water resources Water Framework Directive Watershed Planning and Management World Summit on Sustainable Development

IWRM PAHs RBDs RBM RBMPs SWAP TARWR WFD WPM WSSD

Introduction Water is an essential life-sustaining element of daily life for each and every one. Although water covers more than 70% of the earth’s surface and amounts to 1386 million km3 in the hydrosphere, fresh water that supports human society makes up only 2.53% of the total, of which 1.74% is frozen in the sheets of the Antarctic and the Arctic and in mountain glaciers. Of the remaining fraction (0.79%) of fresh water, more than 99% is stored underground as water (96.2%), ice (2.75%), and moisture (0.16%). The underground fresh water, however, may either exist in the form of ice or moisture that is not available for human use or lie in deep aquifers that cannot be tapped at an affordable cost. The fresh water that humans have direct

access to is found in lakes, rivers, and reservoirs, which only accounts for a tiny portion, i.e., 0.266%, of the total fresh water resources. Although fresh water is a renewable resource in the context of the dynamics of the water cycle, water crisis seemingly becomes inevitable in such a changing world in terms of the variation of global environment, the evergrowing population, and the serious environmental pollution. To cope with the water crisis in both quantity and quality, frameworks for source water management regarding both surface water and groundwater have been proposed all around the world, such as Integrated Water Resources Management (IWRM), Water Framework Directive (WFD) of the European Communities, and Watershed Planning and Management (WPM) and Source Water Assessment and Protection (SWAP) programs of the United States. Meanwhile, with the development of water and wastewater treatment technology, exploitation of alternative water sources, including desalination, rainwater harvesting, and water reuse, has become a global practice to satisfy the thirsty world.

Source Water Quantity Renewal and Withdrawal of Source Water Although fresh groundwater, excluding soil moisture and ground ice, is of a considerably larger quantity (10.53 million km3) than surface water in lakes and rivers (93.12  103 km3), the period of renewal of the former (e.g., weeks to thousands of years) is much longer than that of the latter (e.g., days to tens of years) due to the different pathways through which it is replenished or recharged in the global hydrologic cycle. As shown in Figure 1, the

SO2, NOX Evapotranspiration

Precipitation

Evaporation

Accidental spillage

Petrol station

Evaporation

Acid deposition O

ce

an

River

Runoff

Aquifer

Figure 1

254

Recharge

Hydrological cycle and pollution pathways of the earth’s water resources.

Integrated Management of Source Water Quantity and Quality for Human Health

flow into and through surface water bodies may come from precipitation, runoff from melting snow and ice, human wastewater discharge, and interchange flow from groundwater, whereas groundwater recharge mainly depends on the direct infiltration of rainfall or snowmelt and the replenishment from rivers and lakes as well. Statistics in 2005 estimated the earth’s total annual renewable water resources (TARWR) to be 55 014 km3, which is the maximum theoretical amount of water actually available for human use. As shown in Figure 2, surface water accounted for more than 90% of the TARWR, whereas groundwater only made up less than half in nearly 75% of the countries. Owing to its great renewable amount, relatively easy access, and low withdrawal cost, surface water also dominates the total water abstraction in many countries. Figure 3 compares the contribution of surface water and groundwater to the total water withdrawal in 2000, and the statistical characteristics are quite similar to those in Figure 2. In nearly 80% of the countries, more than 70% of the water

Fraction of the TARWR

1.0 0.8 0.6 0.4 0.2

255

demand was satisfied by surface water, whereas groundwater only provided less than half. Figure 3 also compares the water abstraction by different sectors, and the result shows that more than half of the withdrawn water was used for agricultural production in more than 75% of the countries. Source Water Quantity and Human Health Having enough water for drinking and hygiene purposes promotes better health and well-being. Without essential access to safe drinking water, humans, not to mention animals and plants, cannot survive. Adequate water is also a necessity for food production since it may benefit people’s health through the prevention of malnutrition and thus enable them to more readily recover from illness. Good sanitation, which is critical to human health, also depends on adequate water supply to ensure the safe disposal of human waste and reduce disease and death. Water quantity may also have substantial impacts on human health by adversely changing water quality. Overabstraction of surface water may reduce the flow and thus the self-purification capability of rivers, lakes and reservoirs. Similarly in the case of groundwater, abstraction may bring about strong hydraulic gradients and thus the formation of preferential flow paths, which could reduce the efficacy of attenuation processes and increase the concentrations of contaminants. In coastal areas, seawater intrusion may correspondingly take place. Furthermore, changes in groundwater levels ensuing from abstraction may also change the subsurface environment, e.g., redox conditions, and therefore induce mobilization of contaminants such as heavy metals.

0.0 Surface water

Groundwater

Figure 2 Contribution of surface water and groundwater to the total annual renewable water resources (TARWR) in 159 countries in 2005.

Fraction of the total abstraction

By source

By sector

1.0 0.8 0.6 0.4 0.2 0.0 e

rfac

Su

und

Gro

stic

me

Do

rial

ust

Ind

al ltur

ricu Ag

Figure 3 Contribution of different sources and sectors to the total water abstraction in 2000.

Factors Affecting Source Water Quantity Surface water and groundwater are traditionally regarded as separate entities with respect to water resources management, whereas surface water may interact with groundwater in many situations as illustrated in Figure 1. The water exchange between surface water and groundwater may recharge either of them, depending on the difference between the altitudes of the water surface of the former and the water table of the latter. As a result, withdrawal of water from either of them may deplete water in the other. Moreover, this interaction may also cause changes in water quality in either of them. Therefore, the factors that affect the quantity of surface water and groundwater will herein be simultaneously discussed to address the linkages between these two entities in the hydrological cycle. Climate and geography

As shown in Figure 1, the processes of evaporation and transpiration, i.e., evapotranspiration, act as the driving forces of water transfer in the hydrological cycle, whereas

Integrated Management of Source Water Quantity and Quality for Human Health 104 103

400 Annual precipitation (cm)

(a) Annual renewable surface water resources (km3)

256

102 101 100 −1

10

0−

Annual renewable groundwater resources (km3)

200

100

0

10−2

(b)

300

30

60

− 30

90 0−

6

20

−1 90

80

−1 20

0−10

0+

18

1 Annual precipitation (cm)

Figure 5

10−20 20−30 30−40 40−50 50−60 Latitude (°N or °S)

Effects of latitudes on annual precipitation in 2005.

104 103 102 101 100 10−1 10−2 0−

30

0

−6

30

0

−9 60

20

−1 90

80

1 0− 12

0+

18

Annual precipitation (cm)

Figure 4 Effects of precipitation on renewable water resources in 2005: (a) surface water; (b) groundwater.

precipitation serves as the major recharge source of both surface water and groundwater. All these processes, and thus the quantity of water resources, depend strongly on the meteorological conditions such as solar radiation, temperature, humidity, precipitation, and wind. Figure 4 shows the relation between water resources and precipitation: a noticeable increasing tendency of annual renewable surface water and groundwater resources with precipitation could be observed in the investigated countries. It is also reported that the total precipitation in temperate climate is almost equally divided into three parts, i.e., evapotranspiration, surface runoff, and groundwater recharge. In semiarid climate, however, half of the precipitation returned to the atmosphere through evapotranspiration, and the remaining 30% and 20% goes to surface water and groundwater, respectively. When it comes to arid climate, evapotranspiration may amount to 70% of the total precipitation, whereas only 1% could infiltrate soil and recharge groundwater. Climate varies geographically, and globally speaking, the concentration of atmospheric water vapor, which regulates the quantity of renewable water resources, is the greatest in the tropics and decreases with latitude. Figure 5 presents the distribution of annual precipitation in 189 countries according to their latitudes: a gradual

decrease in precipitation could be noticed when moving from the equator toward the Arctic and Antarctic circles. From the perspective of a local region, the concentration of atmospheric water vapor generally falls along the distance from coastal areas and the altitude above the ground. Figure 6 shows the typical case of China where precipitation decreased with increasing elevation from the southeast coastal areas to the northwest inland areas. Although climate is defined as the long-term prevailing weather in a certain area and traditionally regarded constant, it may be still subject to temporal variations on a global scale, i.e., global climate change and variability, due to the intensive human activities on the earth. As affirmed in the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC), ‘‘Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level.’’ This trend may adversely affect the distribution, availability, and quality of water resources in the whole hydrological cycle through such factors as an increase in precipitation intensity and flooding risk, changes in the seasonal distribution and amount of precipitation and runoff, elevated evapotranspiration and reduced soil moisture, accelerated mass losses from glaciers and reductions in snow cover, and sea-level rise. Topography and geology

When rain falls, vegetation interception, depression storage, runoff, and infiltration take place simultaneously and thus determine the availability of precipitation that actually recharge surface water and groundwater. These processes all depend on the topographical and geological characteristics such as drainage area, basin shape, drainage network pattern, elevation, slope, land use, and soil type. Drainage area, for example, defines the tract of land over which precipitation occurs and contributes to surface runoff and groundwater discharge to a certain water

Integrated Management of Source Water Quantity and Quality for Human Health

257

N

Precipitation in China in 2007 (mm) No data

1000−1500

< 300

1500−2000

300−600

> 2000

600−1000 0

Figure 6

250

500

1000 km

South China Sea Islands

Precipitation in China in 2007.

body, whereas soil type determines the rate at which infiltration occurs, the potential of the aquifer to store water, and the practical yield that can be drained by gravity. Herein land use will be elaborated on as an example with respect to their impact on the quantity of surface water and groundwater as well as the interaction between them. Land use and land use change are closely linked to the water cycle. They may, on the one hand, contribute to climate change and variability by altering the exchange of greenhouse gases and heat between the land and the atmosphere, the radiation balance, and the roughness of the land surface. On the other hand, they can affect the flow regime of the natural hydrological cycle by changing the original land cover, for example, through deforestation, agriculture, and urbanization. Transformation from forest to farmland for food production and from farmland to cities for growing population, which ever happened and now is still happening worldwide especially in the developing world, may alter the distribution of precipitation into interception, infiltration, and runoff and thus influence the recharge of surface water and groundwater.

A study in Shenzhen, China, for instance, showed that forest, grassland, and farmland decreased from 43.4% to 23.6%, from 13.4% to 0%, and from 32.4% to 2.7%, respectively, from 1980 to 2000, while urban area increased from 3.5% to 58.7%. The land use change had been estimated to increase the runoff by 31.8% and 6.8% for antecedent dry and wet soil, respectively, in a 10-year return period of moist year, whereas the maximum flood discharge rose by 28.9% and 2.6% for antecedent dry and wet soil, respectively, in a 20-year return period of moist year. Another study in the arid area of Heihe River basin in China demonstrated the impact of land use change on the annual recharge of groundwater that decreased by 2.033  108 m3 between 1970 and 2000 with the great reduction in grassland (93.8% and 75.1% for highly and moderately covered grasslands, respectively) and forest (16.6%) and a sharp increase in farmland (31.0%), residential land (87.6% and 148.8% for urban and rural areas, respectively), and industrial areas (72%). Land use may also influence the flow conditions at the interface between surface water and groundwater. In flood plains where the groundwater table is generally not far

Integrated Management of Source Water Quantity and Quality for Human Health

below the land surface, vegetation may have root systems deep enough to transpire water directly from groundwater, the rate of which could reach the maximum potential particularly in areas of groundwater discharge. This pumping effect of transpiration of the plants may be so strong during growing seasons that the intercepted and transpired water, which would otherwise flow to surface water bodies, could result in drawdown of the groundwater table. Accordingly, groundwater discharge to surface water bodies would be significantly reduced as compared with that during dormant seasons. Furthermore, the pumping effect of transpiration could be significant enough to cause movement of surface water into the subsurface to replenish the transpired groundwater.

Abstraction and consumption

Fresh water, although a renewable resource, is only renewable within limits, and the extent to which it could meet the demands of the rapid population growth and urbanization is finite. In many parts of the world, e.g., West Asia and North China, human water withdrawal has already exceeded the annual replenishment, whereas in other countries the ratio of abstraction to the average annual resource, although less than unity, has been higher than 40%, in excess of which severe water stress is deemed to occur. Although in some countries, e.g., the USA, Germany, France, Spain, Switzerland, and China, the annual fresh water abstraction has started to decline or has become fluctuant around the possible saturation point even in the presence of noticeable population growth in recent years, increase of the global fresh water withdrawal is almost as inevitable as that of the world population at least in the next several decades. Figure 7 shows the estimates and projections on the annual global fresh water abstraction from 1900 to 2200, resulting from miscellaneous studies since the 1960s that took into account various scenarios regarding population

growth, economy development, climate change, technological evolution, and management policies. In spite of the increase in water use efficiencies, which could be achieved by adopting water-saving techniques, raising the price of water resources, or improving public awareness, it may still be overwhelmed by the strong driving forces of the growing population and its huge demands for food, energy, and well-being. This can be practically identified from Figure 7 regardless of the great variability among the results. Therefore, overexploitation will continuously exacerbate the depletion of available water resources especially in the developing world. The withdrawn water after human consumption, however, could not return to the environment with a quantity equal to withdrawal, and in some cases it could not go back to where it comes from, which causes the hydrological imbalance and thus depletion of the water sources. For surface water, excessive water abstraction, damming, or diversion by the upstream users can limit downstream water use or even dry up the downstream river courses. A study on the Yellow River, the second largest river in China, demonstrates that the dramatic increase in water consumption along the river since the 1950s has caused severe drying up of the lower reaches especially from the 1970s, as shown in Figure 8, until a comprehensive management scheme for water allocation was implemented in 1999. For groundwater, pumping at a rate greater than natural replenishment may cause the drawdown of water table around the well and thus the formation and enlargement of a cone of depression, which could eventually lead to irreversible and disastrous effects such as land subsidence, saline water intrusion, and ingress of polluted water. Investigation in the Yellow River basin demonstrated that overabstraction had already led to the formation of four cones of depression in the deep confined aquifer and six in the shallow unconfined aquifer. One of the cones in the deep confined aquifer in Yuncheng City has enlarged from 1480 km2 in

20

Drying-up reaches (km)

Annual fresh water abstraction of the world (103 km3)

25

15 10 5

800

400

600

300

400

200

200

100

0

0 1900

1950

2000

2050 Year

2100

Figure 7 Estimated and projected annual fresh water abstraction of the world from 1900 to 2200.

2200

1970

Figure 8 1970s.

1980

1990 Year

2000

Annual drying-up days (days)

258

0 2010

Drying up of the Yellow River of China since the

Integrated Management of Source Water Quantity and Quality for Human Health

2000 to 1897 km2 in 2007, and meanwhile the water table of the cone center has dropped from 93.4 m to 103.1 m.

Source Water Quality Characteristics of Source Water Quality Water quality reflects the combined effects of many physical, chemical, and biological processes that water undergoes as it moves along the hydrologic pathways over, under, and through the land. The composition of precipitation falling on the drainage area, the major recharge source of both surface water and groundwater, sets the initial quality of the water, but it is changed thereafter when following different pathways toward the two types of water sources and thus exhibits different characteristics in them. Table 1 compares the statistical characteristics, i.e., quartiles, of water quality parameters between surface water and groundwater derived from a large number of samples in the STORET (STOrage and RETrieval) database developed by the Environmental Protection Agency of the United States. Surface water sources directly receive runoff and sometimes human wastewater discharge as well, and therefore they are generally of a worse quality than groundwater sources. As shown in Table 1, surface water usually contains more nutrients (e.g., phosphorus), pathogens (e.g., total coliform), and suspended solids (e.g., turbidity) than groundwater. Furthermore, surface water quality, e.g., temperature and turbidity, is also subject to great variability due to the gross uncertainty of natural surroundings and human activities, which could also be observed in Table 1 from the interquartile range between the third and first quartiles. Aquatic life such as bacteria, phytoplankton, zooplankton, macrophytes, and fish, for which surface water provides habitats, may also affect water quality. Algae, for example, may bloom unnaturally as a result of massive exogenous nutrients input from human activities, which is symptomatic of eutrophic water bodies. Although producing oxygen during photosynthesis, excessive algae can cause reduced Table 1

259

dissolved oxygen levels when they respire during the night or after they die and are decomposed. Groundwater, on the contrary, is typically of more stable quality and better microbial quality than surface water due to the protection provided by the layers of soil and sediment. These layers effectively filter surface runoff as it percolates through them and thus remove particles, pathogens, and many chemical constituents. Hence groundwater is generally assumed to be a relatively safe drinking water source that requires little or even no treatment. However, groundwater usually contains low dissolved oxygen due to the consumption of microorganisms and reductive chemicals when passing through the soil. Groundwater also tends to be harder due to the elevated concentrations of calcium and manganese dissolved by the infiltrated water through the soil layers.

Source Water Quality and Human Health As shown in Table 1, water contains a wide variety of microbial, chemical, and physical hazards harmful to human health. The most common and widespread health risk is from waterborne pathogens in contaminated drinking water, through which bacteria (e.g., Escherichia coli and Legionella), viruses (e.g., enteroviruses and hepatitis A virus), and protozoa (e.g., Cryptosporidium and Giardia) can be transmitted and can lead to severe and sometimes life-threatening diseases such as diarrhea, typhoid, cholera, and infectious hepatitis. Nevertheless, ingestion of drinking water through the gastrointestinal system is not the only route of infection; some diseases may also result from inhalation of water droplets (aerosols) containing pathogens through the respiratory system or direct contact with water through skin and wounds. In contrast with the acute health concerns caused by pathogens, most chemicals arising in water are of health concern only after extended exposure for years. For example, elevated levels of arsenic naturally occurring in water sources can increase the incidence of cancer at

Water quality of surface water and groundwater

Parameters

Arsenic Chloride Dissolved oxygen Total hardness pH Phosphorus Temperature Total coliform Turbidity

Units

mg l mg l mg l mg l

Surface water

1 1 1 1

CaCO3

mg l 1 1C MPN (100 ml) NTU

1

Groundwater

25th

50th

75th

25th

50th

75th

1.28 10.0 4.77 49.0 6.91 0.016 11.4 125 2.0

2.39 19.0 7.24 87.4 7.64 0.031 17.8 432 5.0

4.10 38.0 8.78 133 8.3 0.072 23.3 880 15.2

1.03 6.88 0.57 138 6.38 0.006 15.1 1 1.1

3.65 17.5 2.26 328 7.13 0.025 21.2 2 4.4

10.0 54.9 4.76 897 7.62 0.070 22.9 3 8.1

260

Integrated Management of Source Water Quantity and Quality for Human Health

several sites, particularly skin, bladder, and lung, in humans through consumption of drinking water as has been proved by the overwhelming evidence from epidemiological studies. Some chemicals, such as nitrate and nitrite, may have acute toxicity especially for specific and vulnerable subgroups, e.g., bottle-fed infants. Radiation constituents resulting from naturally occurring radioactive species or technological processes involving these radioactive materials, e.g., mining, can also increase the long-term incidence of cancer in humans when exposed at low-to-moderate doses. Last but not least, there are some water constituents that have no direct consequence on human health at the normally occurring concentrations, whereas they may be objectionable to consumers for aesthetic acceptability, which is also regarded integral to water safety. For example, although there is no health-based threshold for chloride in drinking water, concentrations in excess of 250 mg l 1 are increasingly likely to be detected by taste. Factors Affecting Source Water Quality

basis, which suggested the significance of limestone weathering in controlling the water quality. Chemical weathering may cause a major health concern at metal and coal mines because of the potentially high concentrations of acidic compounds and trace elements such as arsenic, chromium, cadmium, and lead. It is worthy to note that climate change could also exert adverse influences on water quality. Increased precipitation intensity and floods will transport more pollutants into surface water and may even lead to outbreaks of waterborne diseases, whereas changes in the seasonal distribution and amount of precipitation and runoff, together with accelerated mass losses from mountain snow cover, will reduce the flow and thus the purification capability of surface water during drought periods. Warmer temperatures of surface water are expected to contribute to lower dissolved oxygen and increased algal blooms and add unappealing odor and taste and even cyanotoxin to drinking water. Groundwater in coastal regions, however, is threatened by saline water intrusion due to sea-level rise.

Climate, topography, and geology

Human activities and pollution

When water from rain or snow moves over the land and through the ground, it may flush away plant debris, sand, silt, and clay, dissolve minerals in rocks and soil, percolate through organic materials such as roots and leaves, react with algae, bacteria, and other microorganisms, and thus differ from its original quality. During these processes, land use and geology are the primary determinants for the type of change that water undergoes before its entry into water bodies. For example, surface runoff passing through densely wooded areas or marshy lands may be putridly odorous and highly colored and acidic because of the presence of humic substances, while drainage from farmland may present elevated concentrations of nutrients, minerals, pesticides, and herbicides on account of their application on crops. Geology may also cause site-specific water quality problems such as elevated arsenic in groundwater in the presence of arsenic-rich rocks, minerals, and soil under certain geochemical conditions. Although land use and geology regulate the type of water quality change from precipitation to water sources, the magnitude of this change is more dependent on climate and topography. The combination of frequent heavy rainfalls on steeply sloping land, for instance, will erode and carry away more topsoil and thus contain more suspended solids than when rainfall is moderate or the land is relatively flat. Climate may also play a role in determining the rates of weathering and chemical processes in the watershed and thus influence the recipient water quality. A study on the Mahanadi River in India, for example, showed that calcium and magnesium concentrations were balanced by bicarbonate on an equivalent

Man has long used air, land, and water to dispose wastes such as industrial and vehicle emissions, solid wastes, and wastewater, which in turn affects the quality of precipitation, surface water, and groundwater. Table 2 and Figure 1 show the major pollution sources of water resources and the constituents of concern resulting from various human activities; the principal factors determining the extent to which water quality is contaminated are also given in the table. Regarding water contaminants, developed countries in the last two centuries have experienced a succession of water quality problems relating to pathogens, eutrophication, heavy metals, acidification, organic micropollutants, and sediments from municipal, industrial, and agricultural waste sources. Although following a similar sequence of water pollution problems, rapidly developing countries, e.g., China and India, have encountered all these problems just over decades rather than centuries. From the point of view of pollution sources as listed in Table 2, the pollutants from human excreta and sanitation, industry, mining and military sites, and waste disposal and landfill are usually produced within a confined area and discharged regularly into recipient water bodies at discernible and discrete sites. Traffic and transportation pollution generally occurs along or around the facilities, and therefore the pathway that the pollutants follow into the water environment could also be clearly identified. However, the characteristics of agriculture pollution, a type of nonpoint source pollution or diffuse pollution, are quite different from the former four pollution sources. Agricultural pollution is generated over an extensive area, moves overland, and enters recipient

Integrated Management of Source Water Quantity and Quality for Human Health Table 2

261

Pollution sources of water resources and constituents of concern from various human activities

Sources

Human activities

Constituents of concern

Major determinants

Human excreta and sanitation

Open air defecation, onsite sanitation, and offsite sanitation, i.e., domestic sewage

Agriculture

Use of fertilizers and manures

Nutrients, organic matter, pathogens, detergents, pharmaceuticals, personal care products, and industrial pollutants Nutrients (nitrogen, phosphorus, and potassium), organic matter, and pathogens

Design and operation of facilities, hydrogeological conditions, connection with industries, spills, leaks, and overflows Rates and timing of application, type of crops, soil conditions, climate, irrigation, and manure treatment Washdown, treatment and storage facilities, animal diseases, climate, and hydrogeological conditions Sources of wastewater, treatment and storage facilities, hydrogeological conditions, and rates and timing of application Chemical and physical properties of chemicals, hydrogeological conditions, and rates and timing of application Irrigation and drainage techniques, irrigation water quantity and quality, design of drainage system, and hydrogeological conditions Processes and chemicals in use, age and size of facilities, hydrogeological conditions, and environmental management practices Traffic volume, transport of hazardous goods, accident rates, accident prevention measures and response plans, condition and technical design of the traffic-related facilities, and hydrogeological conditions Waste composition and loading, methods of treatment and disposal, design and age of facilities, environmental management practices, and hydrogeological conditions Emissions of sulfur dioxide and nitrogen oxides, and chemistry and buffering capacity of the water and soils

Animal feeding and disposal of animal carcasses

Industry, mining, and military sites

Traffic and transportation

Waste disposal and landfill

Acid deposition

Use of wastewater and sewage sludge on land and in aquaculture

Nutrients, organic matter, pathogens, and growth hormones and pharmaceuticals Nutrients, organic matter, pathogens, and persistent organic chemicals

Use of pesticides and herbicides

Persistent organic chemicals

Irrigation and drainage

Nutrients, salinity, pesticides, herbicides, and sometimes fluoride, arsenic, selenium, and heavy metals

Transfer and storage of raw materials and final products, production, packaging, storage, and disposal of waste products Roads, airfields, railway lines, inland waterway transportation, pipelines and storage of crude oil and oil derivatives, fire fighting, and construction and maintenance of transport associated facilities Waste storage, treatment, and disposal sites

Nutrients, heavy metals, chlorinated solvents, benzene, arsenic, radioactive elements, explosives, etc.

Fossil fuel combustion such as heating, electricity production, and driving vehicles

pH, hardness, aluminum, mercury, zinc, copper, cadmium, and lead

water in a diffuse manner at intermittent intervals related mostly to uncontrollable meteorological events. Therefore, the extent of agriculture pollution is closely related to climatic, geographic, and geologic conditions and may vary greatly from place to place and from year to year. The 2000 national water quality inventory of the United States indicated that agriculture impacted 48% of the impaired river miles, whereas in the United Kingdom,

Mineral oil hydrocarbons, herbicides, heavy metals, deicing agents, etc.

Nutrients, organic matter, pathogens, metals

53% of the phosphorus and 64% of the nitrogen discharged into surface water originated from agriculture. In developing countries, taking China for example, agriculture was estimated to constitute 36–70% of nitrogen load and 39–65% of phosphorus load to the Chaohu Lake, whereas its contribution to Dianchi Lake and Taihu Lake was 30–53% and 40–86%, respectively, for nitrogen and 30–59% and 38–90%, respectively, for phosphorus.

262

Integrated Management of Source Water Quantity and Quality for Human Health Process of developing an IWRM strategy

Acid deposition is not as common as the other five pollution sources and is only critical in certain countries and regions. Acidification of surface water became a serious problem in the 1960s and 1970s in the developed world, particularly in Scandinavia, Western and Central Europe, and the northeast of North America, where the water quality of lakes and streams were impaired by low pH levels, decreasing acid-neutralizing capacity, and elevated aluminum concentrations. This situation has also emerged as an important issue in some developing countries with increasing industrialization such as China and India.

Table 3

Integrated Management of Water Sources

Build commitment to actions

Source water quantity and quality are affected by a great variety of factors, natural, anthropogenetic, local, regional, or global. Therefore, management of source water calls for a holistic, integrated, and collaborative approach. A holistic perspective should be held in mind that water quantity and quality are related and should be considered together, while different water bodies, either surface and ground or inland and costal, may also be connected and should be regarded in the context of the whole hydrological cycle. Management of source water is also a scientific and technical issue in an extremely complex and mixed system across natural environment and human society, and hence it needs an integration of multidisciplinary work, including meteorology, geography, geology, hydrology, hydraulics, ecology, chemistry, biology, demography, economics, sociology, and technology. Moreover, source water management, in the social aspect, requires a collaborative framework within which the concerned regions, sectors, and users should be involved, such as land use planning, agriculture, forestry, flood management, industry, tourism, and recreation. Some international organizations and developed countries have already devised and adopted such approaches to source water management, and herein IWRM, WFD, WPM, and SWAP programs are briefly introduced. IWRM IWRM, as the Global Water Partnership defined, is the process of promoting the coordinated development and management of water, land, and related resources, to maximize the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems. In an effort to encourage a move toward more sustainable approaches to water development and management, the World Summit on Sustainable Development (WSSD) in 2002 called for all countries to develop IWRM and water efficiency plans by 2005.

Steps

Tasks

Establish status and overall goals

Water resource issues Goals and progress toward IWRM framework Recent international developments Political will Awareness Multistakeholder dialogue Water resource management functions required Management potentials and constraints Enabling environment Institutional roles Management instruments Links to national policies Political adoption Stakeholder acceptance Identify financing IWRM framework Framework for water infrastructure development Build capacity Indicators of progress toward IWRM and water infrastructure development framework

Build commitment to reform process Analyze gaps

Prepare strategy and action plan

Implement frameworks

Monitor and evaluate progress

IWRM aims to support countries in their efforts to tackle specific water challenges, e.g., water scarcity, waterborne diseases, floods, droughts, and access to water and sanitation, and thus sustain their development to achieve the goals such as poverty alleviation, food security, economic growth, and ecological conservation. However, IWRM is not just about managing physical resources; it also requires and promotes the positive changes in water governance regarding the enabling environment, institutional roles, and management instruments. Table 3 shows the major steps and tasks of developing an IWRM strategy. Although the IWRM strategy is shown in a logical sequence in the table, it is by no means a one-shot and linear process but a longterm and iterative one. IWRM systems should, therefore, not only be responsive to changes among its development process, for example, between projected goals and decision-makers’ willingness, but also be capable of adapting to new economic, social, and environmental conditions and to changing human values over a longterm implementation. WFD In 2000, the European water policy underwent a thorough restructuring process, and a new WFD was adopted, which set the objectives for water protection and also provided the operational tools for all the member states of European communities. The purpose of WFD is to protect and enhance the status of aquatic ecosystems through

Integrated Management of Source Water Quantity and Quality for Human Health

progressive reduction of discharge, emissions, and losses of pollutants, promote sustainable water use based on longterm protection of available water resources, and mitigate the effects of floods and droughts. WFD introduced the concept of river basin management (RBM), and the member states were required to establish river basin districts (RBDs) as the basic management units and produce river basin management plans (RBMPs). The RBMP records the current status of water bodies and significant pressures and impact of human activities on water resources within an RBD, establishes environmental objectives for water resources and protected areas, and formulates program of measures to meet the objectives, e.g., legislation enforcement, recovery of the costs of water use, protection of drinking water sources, registration and control on abstraction and impoundment of water, management of pollutants discharge, and prevention of accidental pollution incidents. The planning process of RBM is given in Table 4 and it is also a nonlinear iterative process.

Table 4

Planning process of RBM

Steps

Tasks

Set the scene

Identify the RBD Establish appropriate administrative arrangements for coordination of activities Designate competent authorities Provide general description of the RBD Maintain a list of protected areas Evaluate the gap between current status and objectives Identify significant pressures and assessment of their impacts Perform an economic analysis of water uses Establish provisional reference conditions Establish reference conditions and ecological quality class boundaries Carry out intercalibration Establish monitoring programs taking into account the identification of water bodies at risk of failing the objectives Verify and refine the preliminary gap analysis Evaluate whether cost for closing the gap is disproportionate and justify potential derogations Decide on deadline extensions and application of less stringent objectives Define potential measures Analyze the cost-effectiveness of potential measures Set up a cost-effective program of measures Finalize the detailed program of measures Provide an interim overview of significant water management issues Complete the draft RBMP and make it available for comments to the public Produce a summary of the program of measures Finalize and publish RBMP Make the program of measure operational Prepare an interim report describing progress in the implementation of the planned program of measures Update the RBD status Review the program of measures and the RBMP Establish effective mechanisms for public participation in planning and decision-making right from the start of the planning process

Assess the current status and preliminary gap analysis

Set up environmental objectives

Establish monitoring programs

WPM and SWAP Programs In the United States, there has been a move toward managing water quality through a watershed approach since the late 1980s. It is a flexible framework for managing water resource quality and quantity within specified drainage areas or watersheds through stakeholder involvement and management measures supported by sound science and appropriate technology. WPM works within this framework by using a series of cooperative and iterative steps, as shown in Table 5, to characterize existing conditions, identify and prioritize problems, define management objectives, develop protection or remediation strategies, and implement and adapt selected actions as necessary. SWAP programs delineate protection areas for source water of public drinking water supplies, identify potential sources of contaminants within the areas, determine the susceptibility of the water supplies to contamination from these potential sources, and make the results of the assessments available to the public. WPM may provide information for SWAP programs, whereas integrating SWAP programs into WPM and targeting source water as protection areas of high priority will result in better understanding of the most critical pollutant sources and opportunities to leverage limited resources to meet common goals.

Alternative Water Sources Although great efforts have been devoted to water resource protection in many countries, water stress still becomes poignant due to population growth, lifestyle change, and environmental pollution. Consequently,

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Gap analysis

Set up program of measures

Develop RBMP

Implement RBMP and prepare the interim report on the implementation

Evaluate the first and prepare the second period Public information and consultation

264 Table 5

Integrated Management of Source Water Quantity and Quality for Human Health Process of WPM

Steps

Tasks

Build partnerships

Identify driving forces Identify and engage stakeholders Integrate with local, state, tribal, and federal programs Conduct public outreach Identify issues of concern Define the geographic extent of the watershed Develop preliminary goals Select indicators to measure environmental conditions Link concerns with goals and indicators Determine data needs Identify available data Locate the information Gather and organize necessary data Create a data inventory Conduct a data review, i.e., identify data gaps and determine acceptability of data Design a sampling plan and collect new data if needed Analyze data Identify causes and sources of pollution that need to be controlled Estimate pollutant loads Set overall goals and management objectives Develop indicators/targets Determine load reductions needed Review existing management efforts to determine gaps Develop criteria to screen possible management options Identify critical areas Identify costs and compare benefits of management practices Select final management strategies Establish an implementation schedule Develop interim milestones to track implementation of management measures Establish criteria to measure progress toward meeting watershed goals Develop a monitoring component Develop an information/education component Identify technical and financial assistance needed to implement plan Develop an evaluation framework Assign responsibility for reviewing and revising the plan Implement management strategies Conduct monitoring Conduct information/education activities Review and evaluate information Share results Prepare annual work plans Report back to stakeholders and others Make adjustments to program

Characterize the watershed

Finalize goals and identify solutions

Design an implementation program

Implement watershed plan

Measure progress and make adjustments

alternative water sources have been exploited besides the traditional surface water and groundwater sources, and it has become a common practice to involve exploitation of alternative water sources in water management strategies. Desalination Although oceans contain 96.5% of the water of the hydrosphere, i.e., 1338 million km3, they are traditionally deemed only important for transportation and fisheries. They could not sustain human life or farming due to high salinity. However, the development of desalination techniques, such as membrane processes, has increased the range of water resources available for human consumption, especially in arid regions. The concept of using desalinated water for municipal water supplies has become commonplace since the 1990s due to the success of the technology, the steady decrease in its overall cost, and the continual pressure on conventional water sources. At the end of 2004, there were approximately 10 597 desalination plants in the world and the capacity amounted to 20 km3, which was approximately equivalent to 5% of the total water withdrawal for domestic uses presently. More than 60% of the desalinated water went to domestic uses, which is followed by industry use of 25%. Despite the dramatic decrease in the production cost in the last two decades, future development of desalination still faces the challenges from high energy consumption and disposal of brine waste by-products. Rainwater Harvesting The earth’s atmosphere is also a large pool of fresh water, the amount of which is almost six times that in rivers and streams, and constitutes the primary sources for all fresh water on the planet. Rainwater harvesting is the capture and storage of rainwater for purposes such as landscape irrigation, potable and nonpotable indoor uses, storm water abatement, and groundwater recharge. The practice of rainwater harvesting can be classified into two broad categories, i.e., land-based and roof-based. Landbased rainwater harvesting is to intercept the surface runoff and collect it in dikes, ponds, tanks, and reservoirs, whereas roof-based rainwater harvesting refers to collecting rainwater runoff from roof surfaces. The latter obviously results in a much cleaner source of water and could be easily implemented at household level for domestic uses. Rainwater harvesting has many advantages, such as free acquisition, good quality, in situ use, reduction of surface runoff and nonpoint source pollution, and mitigation of the demand peak and expansion of existing water supply systems. Harvested rainwater can be particularly useful when no other water sources are available, or if the available water supply is inadequate or of poor quality. Major concerns regarding rainwater harvesting include low reliability as a long-term and

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drought-proof water source, careful maintenance after installation, space needed for storage around the house, and relatively higher capital cost than that of obtaining water from a centralized distribution system. However, water quality may become the predominant concern if rainwater is harvested for potable purpose since both air quality and roof and tank materials may add hazardous contaminants, such as lead and polycyclic aromatic hydrocarbons (PAHs) to the collected water. A study in Australia demonstrated that atmospheric deposition did contribute to contaminants in rainwater in an urban environment with traffic as the major contributor; therefore, its impact on water quality should be considered for rainwater harvesting in urban areas subject to significant air pollution.

(9%). In addition to providing a dependable and locally controlled water source, water reuse brings tremendous environmental benefits, such as decreasing water diversion from or wastewater discharge to sensitive ecosystems, reduction and prevention of pollution, and creation, rehabilitation, or improvement of wetlands and riparian habitats. Water reuse is regarded as a sustainable approach and can be cost-effective in the long term; however, treatment of wastewater to an appropriate quality for reuse and the capital cost for installing new distribution systems can initially be expensive compared to the existing water supply systems. Furthermore, water reuse should also take public acceptance and security into account.

Water Reuse

See also: Worldwide Regulatory Strategies and Policies for Drinking Water.

Water reuse generally refers to the process of using treated wastewater (reclaimed water) for beneficial purposes such as agricultural and landscape irrigation, industrial processes, nonpotable urban applications (such as toilet flushing, street washing, and fire protection), groundwater recharge, recreation, and direct or undirected water supply. Its increased application has been facilitated by modern wastewater treatment processes that have advanced substantially during the twentieth century. These processes can now effectively remove biodegradable materials, nutrients, and pathogens, so the treated water has a wide range of potential applications. Although nonpotable water reuse is overwhelmingly dominant on a global scale, reuse as potable water has been accepted for centuries since downstream users virtually produced their potable water from rivers and groundwater that had circulated upstream through multiple cycles of withdrawal, treatment, and discharge. In Australia, the supply of reuse water increased from less than 1% of total supply to nearly 4% between 1996–97 and 2004–05, and agriculture used 66% of the reuse water, followed by irrigation use in parks, gardens, and sporting fields (14%) and the water supply industry

Further Reading Gower AM (1980) Water Quality in Catchment Ecosystems. Chichester: Wiley. Schmoll O, Howard G, Chilton J, and Chorus I (eds.) (2006) Protecting Groundwater for Health: Managing the Quality of Drinking-Water Sources. London: IWA Publishing. Shiklomanov IA and Rodda JC (2003) World Water Resources at the Beginning of the Twenty-First Century. Cambridge: Cambridge University Press. United Nations Educational, Scientific and Cultural Organization (UNESCO) and World Water Assessment Programme (WWAP) (2003) Water for People, Water for Life. Barcelona: Berghahn Books. United Nations Educational, Scientific and Cultural Organization (UNESCO) and World Water Assessment Programme (WWAP) (2006) Water, A Shared Responsibility. Barcelona: Berghahn Books. US Environmental Protection Agency (2008) Handbook for Developing Watershed Plans to Restore and Protect Our Waters. Washington, DC: Office of Water. Viessman W and Lewis GL (1996) Introduction to Hydrology, 4th edn. New York: HarperCollins College Publishers. Winter TC, Harvey JW, Franke OL, and Alley WM (1998) Ground Water and Surface Water: A Single Resource. Denver: U.S. Geological Survey. World Health Organization (WHO) (2004) Guidelines for Drinking-Water Quality, 3rd edn., vol. 1. Recommendations. Geneva: WHO.