.
UNIVERSIDADE POSITIVO
LIGIE ELENA DALL’AGNOL ACEVEDO
RIVER RECOVERY: diagnostic tool and proposal of rehabilitation programs
CURITIBA 2015
RIVER RECOVERY: diagnostic tool and proposal of rehabilitation programs
Dissertation presented as partial requirement for the degree of Master of Applied Science in Environmental Management, in the Graduate Program in Environmental Management at Universidade Positivo (UP).
Supervisor: Prof. Maurício Dziedzic
CURITIBA 2015
Dados Internacionais de Catalogação na Publicação (CIP) Biblioteca da Universidade Positivo - Curitiba - PR
A174 Acevedo, Ligie Elena DallAgnol
River recovery: diagnostic tool and proposal of rehabilitation programs / Ligie Elena DallAgnol Acevedo. ― Curitiba: Universidade Positivo, 2015.
126 p. : il.
Dissertação (Mestrado) – Universidade Positivo, Departamento de Gestão Ambiental, 2015.
Orientador : Prof. Dr. Maurício Dziedzic.
1. Qualidade ambiental. 2. Restauração - rios. 3. I.Título. II.
Dziedzic, Maurício
CDU 504.3.054
ACKNOWLEDGEMENTS
I would like to give my special thanks to my supervisor Prof. Maurício Dziedzic, for whom I have immense admiration, thank you for guiding my research and for the opportunity, also thank for your dedication in guiding my steps so patiently. I also wish to thank Prof.
Klaus Dieter Sautter, who introduced me to the program and for his recommendations as a thesis committee member. I also acknowledge with gratitude Prof. William Bonino Rauen and Prof. Cristóvão Vicente Scapulatempo Fernandes for the contributions to the thesis during the examination process.
This research would not have been possible without the essential and gracious support of my parents, Silvana Dall`Agnol Acevedo and Hector de Mata Acevedo Marin, and all my family, specially Helena Dall`Agnol Verardi and Andreize Dall`Agnol Acevedo, Christian Dall`Agnol Acevedo, Daiane Dall`Agnol Acevedo, Isabela Acevedo Quadros and Cauã Acevedo Quadros.
I thank my study mates who have supported me throughout the entire process, by keeping me harmonious and helping me put pieces together, thank Sabrina Louise de Morais Calado and Lilian Dalago Salgado for being my inspiration, thank you Maryana Linhares Cordeiro for always motivating me and for the support with legal information. I also want to thank my master's classmates, Ana Camila dos Santos Ferraresi and Rafaella Loffredo for sharing the feelings of this journey.
I would like to thank my loved one, Marcel Favery Nogueira, for your patience. I am grateful for your love.
Thanks to all the individuals and organizations for the generous and varied contributions to this research.
ABSTRACT
Rivers are subjected to human impacts that transform the natural landscape into areas of environmental degradation, compromising biodiversity and reducing the quality and quantity of available water. Promoting the environmental recovery of watercourses is of paramount importance to the health of ecosystems and sustainability of economic systems alike. In this context, the effectiveness of programs for environmental rehabilitation of aquatic ecosystems requires a tailored restoration approach based on scientific knowledge, which associates physical, chemical, biological, cultural and social interactions. The preparation of a recovery plan requires the association of tools to obtain a diagnostic of the river environmental quality based on analysis of the root causes, associated problems, and possible solutions. Thus, the work described herein aimed to develop a diagnostic guide of river environmental quality to base the implementation of restoration programs. The research was composed of four main stages: I – elaboration of summary matrices correlating river problems, their causes, and possible solutions; II - development of a guide to instruct data collection for application of the tool; III – test application of the products resulting from steps I and II to a segment of the Passaúna river, situated in the Southern Brazilian metropolitan region of Curitiba; IV – data analysis and suggestion of structure for the Passaúna river recovery program. The tool was developed from the organization of scientific and technical data. The information is divided into six summary matrices that relate the root and immediate causes of problems, which are:
pollution, flood, loss of aquatic biodiversity, loss of riparian zone biodiversity, loss of navigability, and impairment of hydropower generation. Results include the application of the tool in the segment upstream of the Passaúna reservoir, one of the main sources of water supply to Curitiba and its metropolitan region. Considering the river problems identified, some guidelines to elaborate management plans were proposed involving land use, monitoring and environmental education.
Keywords: environmental quality, river restoration, management tool.
RESUMO
Os rios são impactados por atividades humanas que transformam a paisagem natural em áreas de degradação ambiental, comprometendo a biodiversidade e reduzindo a qualidade e a quantidade de água disponível. Promover a recuperação ambiental dos cursos hídricos é importante para a saúde dos ecossistemas e sustentabilidade dos sistemas econômicos. Neste contexto, a eficácia dos programas de reabilitação ambiental dos ecossistemas aquáticos requer uma abordagem baseada no conhecimento científico que associe as interações dos processos físicos, químicos, biológicos, culturais e sociais. A preparação de um plano de recuperação requer a interação de ferramentas que resultem em um diagnóstico da qualidade ambiental do rio baseado na análise das causas fundamentais, assim como dos problemas associados e possíveis soluções. Assim, o trabalho aqui descrito teve como objetivo desenvolver um guia de diagnóstico da qualidade ambiental de rios para direcionar a execução de projetos de recuperação. A pesquisa foi executada em quatro etapas principais: I - elaboração de quadros resumo correlacionando os problemas dos rios e suas causas com possíveis soluções. II - desenvolvimento de um guia para orientar a coleta sistemática de dados para aplicação da ferramenta. III – teste da aplicação dos produtos resultantes das etapas I e II em um segmento do rio Passaúna, situado na região metropolitana de Curitiba. IV – análise, associação dos dados e sugestão de ações para estruturar o programa de recuperação do rio Passaúna. A ferramenta de diagnóstico foi construída a partir da organização de dados científicos e experimentais em seis quadros resumo que relacionam as causas fundamentais e imediatas com os problemas de: poluição, cheias, perda de biodiversidade aquática, perda de biodiversidade terrestre, perda de navegabilidade e redução do potencial de geração de energia. Os resultados também incluem o exemplo de aplicação da ferramenta no segmento a montante do reservatório do Passaúna, um dos principais mananciais de abastecimento de Curitiba e região metropolitana. A partir dos problemas identificados foram propostas algumas orientações visando contribuir com o gerenciamento da recuperação ambiental do rio por meio de projetos de monitoramento, educação ambiental e regularização do uso do solo.
Palavras-chave: qualidade ambiental, restauração de rios, ferramenta de gestão.
LIST OF FIGURES
Figure 1 – Types of organisms in the clean zone and pollution zones Figure 2 – Point and non-point source of river pollution
Figure 3 - Conceptual framework used for the development of the RIMAM model Figure 4 – Passaúna Watershed Location
Figure 5 – Passaúna EPA Ecological Economic Zoning. The box indicates the segment studied and the labels indicate the adjacent zones
Figure 6 - Aerial view of the Passaúna river, with the place-mark indicating the location of the point in the middle of the segment selected for the case study
Figure 7 - Site used for case study – (a) view looking at the area from the highway BR- 277; (b) view looking at the Passaúna river just upstream from the highway BR-277 bridge.
Figure 8 - Passaúna EPA showing urban and rural areas
21 35 54 84 87
88
88
89
LIST OF TABLES
Table 1- Pollution zones in a river or stream 19 Table 2 - Main characteristics of river rehabilitation programs. 49 Table 3 - Immediate and root causes of river problems, and possible solutions.
Table 4 - River Management Summary Matrix Application.
Table 5 - Immediate and root causes of river pollution, and possible solutions.
Table 6 - Immediate and root causes of river floods, and possible solutions.
Table 7 - Immediate and root causes of aquatic biodiversity loss, and possible solutions.
Table 8 - Immediate and root causes of riparian zone biodiversity loss, and possible solutions.
Table 9 - Recommended width of the riparian zone.
Table 10 - Passaúna EPA population growth.
Table 11 - RIMAM Passaúna River Application – Pollution.
Table 12 - RIMAM Passaúna River Application – River flood.
Table 13 - RIMAM Passaúna River Application – Aquatic biodiversity loss.
Table 14 - RIMAM Passaúna River Application – Riparian zone biodiversity loss.
53 55 58 59 60 60
64 85 90 91 91 91
LIST OF ABBREVIATIONS
AR - Araucaria Forest AUZ - Agricultural Use Zone
BOD - Biochemical Oxygen Demand BWS – Biodiversity Water Security COD - Chemical Oxygen Demand
CONAMA - National Council of the Environment
COMEC - Commission of the Curitiba Metropolitan Region CMR - Curitiba Metropolitan Region
DRF - Dense Rain Forest
EEZ – Ecological Economic Zoning EIA - Environmental Impact Assessment EPA - Environmental Protection Areas ESA – Environmentally Significant Area
FERC - Federal Energy Regulatory Commission GIS – Geographic Information System
HWS - Human Water Security IAP - Paraná Environmental Institute
IBGE - Statistic and Geographic Brazilian Institute IC - Immediate Cause
IUWM - Integration of Urban Water Management MFO - Mixed Rain Forest
NEP - National Environmental Policy NGOs - Non-Governmental Organizations NPS - National Park Service
NSUC - National System of Units Conservation OM - Organic Matter
OOZ - Oriented Occupation Zone RBPZ - River Bottom Protected Zone RCA - Root Cause Analysis
RC - Root Cause
RIMAM – River Management Matrix RRC – River Restoration Centre
SANEPAR - Paraná Environmental Sanitation Company SPM - Suspended Particulate Material
USAID - United States Agency for International Development USLE - Universal Soil Loss Equation
WIPS - Watershed Integrated Protection System WQI - Water Quality Index
SUMMARY
1 INTRODUCTION 12
1.1.1 Main objective 15
1.1.2 Specific objective 15
2 LITERATURE REVIEW 16
2.1 WATER RESOURCES 16
2.2 WATER ECOSYSTEMS AND ECOLOGICAL SERVICES 16
2.2.1 Hydrologic Cycle 17
2.2.2 Elements cycle 18
2.2.3 Riparian zone 21
2.3 WATER QUALITY 23
2.3.1 Quality criteria in fresh water 23
2.3.2 Classification of freshwater quality 23
2.3.3 Water Quality Index 23
2.3.3.1 Temperature 24
2.3.3.2 pH 24
2.3.3.3 Electrical conductivity 24
2.3.3.3 Dissolved Oxygen (DO) 24
2.3.3.4 Turbidity 25
2.3.3.5 Total solids 25
2.3.3.6 Nitrogen (N) 25
2.3.3.7 Phosphorus (P) 26
2.3.3.8 Fecal coliforms 26
2.3.3.9 Biochemical Oxygen Demand/ Chemical Oxygen Demand (BOD/COD) 26
2.3.4 Sediment 27
2.3.4.1 Siltation 28
2.4 SOCIETY AND RIVERS 29
2.4.1 Influence of society on water quality 30
2.5 CAUSES OF WATER RESOURCES DEGRADATION 34
2.5.1 Disturbance of water systems 35
2.5.1.1 Domestic sewage 35
2.5.1.2 Agriculture sewage 36
2.5.1.3 Industrial sewage 36
2.5.1.4 Urbanization 37
2.5.1.5 Eutrophication 37
2.5.1.6 Dams 38
2.6 ISSUES OF REHABILITATION PROGRAMS 39
2.6.1 Environmental Impact Assessment (EIA) 40
2.6.2 Managing Rivers 40
2.6.2.1 River Rehabilitation Programs 41
3 METHODS 51
3.1 DEVELOPMENT OF THE RIVER MANAGEMENT MATRIX (RIMAM) (PHASE I) 51
3.1.1 Definitions 51
3.1.2 Finding out about the River Problems and Possible Solutions 52
3.1.3 Preliminary RIMAM application 55
3.2 RIVER MANAGEMENT SUMMARY MATRIX USER GUIDE (PHASE II) 55
3.3 APPLICATION EXAMPLE (PHASE III) 55
3.4 GUIDELINES FOR ACTION PLANS (PHASE IV) 56
4 RESULTS AND DISCUSSION 57
4.1 RIVER MANAGEMENT SUMMARY MATRIX 57
4.2 RIVER MANAGEMENT MATRIX USER GUIDE 61
4.3 CASE STUDY 83
4.3.1 Study Area 83
4.3.1.1 Description of the segment select as the case study 85 4.3.2 River Management Matrix (RIMAM) (Example of application) 89
4.4 GUIDELINES FOR ACTION PLANS 92
4.4.1 Regulate land use 92
4.4.2 Environmental education programs 94
4.4.3 Improve monitoring practices 94
4.4.4 Improve management practices 95
5 CONCLUSION 96
5.1 RECOMMENDATIONS FOR FUTURE WORK 97
5.1.1 River Management Matrix (RIMAM) 97
5.1.2 Passaúna river restoration 98
REFERENCES 99
APPENDICES 113
1 INTRODUCTION
Water is a vital natural resource, its control and exploitation are a constant challenge, leading to its classification as the most problematic, contradictory, and complex element of nature (LAMAS, 2005). Despite being indispensable, failure in managing its use is compromising the quality and quantity of water available (GORSKI, 2010; AFONSO, 2011;
CUNHA et al., 2011a), as well as strongly affecting biodiversity patterns in around water bodies (GOMEZ-SALAZAR et al., 2012).
Rivers are sources of supply and provide ecological services that maintain the balance of life on the planet. This natural resource and the services it provides, which combined are known as natural capital, in conjunction with human actions produce a wide variety of products and services distributed, and used by the world’s population (MILLER;
SPOOLMAN, 2006). The rapid flow of material supply through the economic systems is depleting natural capital, and generating heat, pollution, and waste (BISWAS, 1996; BENKE;
CUSHING, 2005; MILLER; SPOOLMAN, 2006). Pollution modifies the trophic levels, damaging the dynamics of the energy cycle in all ecosystems (BEGON et al., 2006). Aquatic environments are highly connected, thus water, inorganic compounds and organic matter are drained, dispersed, and spread throughout water bodies, increasing the vulnerability of these ecosystems. Human health is also affected - among other consequences, part of the population lack access to clean water, and/or do not have access to adequate sanitation (BISWAS, 1996;
BENKE; CUSHING, 2005; MILLER; SPOOLMAN, 2006).
Maintaining a sustainable relationship between people and the natural environment requires establishing a balance between the technologies and nature’s ability to fulfill human needs (UNESCO, 2012). Some steps were taken by the primary sector in order to reconcile economic development and environmental protection. The need to curb pollutant emissions to freshwater habitats has resulted in the introduction of significant water policy instruments worldwide. The international community is cooperating through the alliance of multidisciplinary groups that strengthen the policies to manage water resources (RRC, 2011).
The reestablishment of the environmental balance of water systems involves a wide range of institutions and actors at local, state, national, regional and international levels where rules and principles of different origins and legitimization coexist and interact.
Current publications highlight the need to improve the understanding of underlying causes to be able to counteract the current and future water threats to public health, economic progress, and biodiversity. Recognizing the cause of water resources changes is a special challenge to scientific research. In addition, rather than concentrating on a particular aspect of the global water system, scientists must especially study the linkages and feedbacks in the system (GWSP, 2005).
There are many tools and instruments designed to classify the quality of water resources, but information about and strategies for river recovery are still disconnected, and not widely accessible (GWSP, 2005; UNESCO, 2012). Development of a computational system based on experiences and scientific data may contribute to the solution of problems through the organization and distribution of information. It is also important to connect the tools of river management in order to create complete and appropriate recovery actions based on the relations between problems and their causes. The development of diagnostic and management tools is an essential contribution and literature reveals the need for more complete freshwater datasets to guide water management practices beyond policies (MUELLER, et al., 2015). There is still a lack of structure, specific research, and dissemination of management possibilities in order to raise their success capacity (GORSKI, 2010). This is directly related to the lack of a complete diagnostic, which would be better suited to identify all factors affecting the system. Therefore, it is essential to identify and correlate problems with their possible causes through a systematic approach. Integrated management systems are considered a crucial step for the restoration, and maintenance of water resources (TUNDISI, 2006; GORSKI, 2010). An effective conservation and recovery program of aquatic ecosystems should correlate processes and mechanisms and the multiple factors and variables involved (GORSKI, 2010).
In Brazil, the contamination of water supplies greatly compromises the environmental quality of this resource (GORSKI, 2010). The national rivers have undergone one of the worst impacts, the transformation of the landscape in areas of social conflict, and environmental degradation. Some of strategies to change the situation involve the creation of Environmental Protection Areas (EPAs) by Federal Law no 9.985 of July 18, 2000. This law creates the National System of Conservation Units (NSUC), and regulates the use of these areas (BRAZIL, 2000). Curitiba and its Metropolitan Region, in southern Brazil, have undergone great expansion, and population growth. Seeking to ensure the protection of water sources, the State Decree 458/91 of the State of Paraná regulates the creation of the Passaúna EPA with an
area of 16,020.04 ha (PARANÁ, 1991). Located in the Passaúna river basin, the Passaúna EPA, is one of the largest sources of local water supply evidencing that efforts must be made to preserve the natural systems and to guarantee the water provision for approximately 67.000 citizens (IBGE, 2010). The Passaúna river is a tributary of the Iguaçu river, its basin encompasses approximately 188 km2, including 11 km2 of the reservoir surface area (VEIGA;
DZIEDZIC, 2010).
The EPA management plan describes the Ecological Economic Zoning (EEZ) as a tool to regulate conflicts arising from the various, and antagonistic uses of the basin. However, in most cases, even these actions cannot guarantee the environmental protection. In the case of the Passaúna river, surveys conducted by different sectors of society aim to monitor its conditions, by the analysis of physical, chemical, biological, cultural, and social variables.
The results show anthropic impacts pressing the river and the quality of its water, and point to the need for actions to ensure the conservation and recovery of degraded stretches of the river, selected to exemplify the application of the tool developed in the present work.
Thus, the approach devised consisted of four main phases. The first phase comprised the compilation of a summary matrix listing problems, respective causes of river degradation, and possible solutions. Phase II consisted of developing a guide to use the summary matrix considering that a systematic data collection is required to develop a comprehensive environmental diagnostic of the river. In phase III the result of steps I and II were combined with the information from the Passaúna river in order to prepare a diagnostic of the river. The last stage, phase IV, developed guidelines to establish action plans to guide the Passaúna river restoration program. These steps can be used to direct the organization of data that are necessary for an understanding of a river, and its problems as a whole.
Hence, the work described herein was developed considering: i) the relevance of a systemic process to structure comprehensive programs of river recovery; ii) the possibility of developing systemic methodologies for application in the field of organizational intervention;
iii) the possibility of involving many factors and variables for the understanding of the same problem; and iv) the need for well-structured river recovery programs based on scientific knowledge. The approach proposed here is intended to serve as a basic step in the development of river recovery programs, and thus help to improve such projects worldwide.
1.1 OBJECTIVES 1.1.1 Main objective
Develop a systemic process to structure river recovery programs through the use of a diagnostic system.
1.1.2 Specific objective
Apply the systemic process developed to a segment of the Passaúna river.
2 LITERATURE REVIEW
2.1 WATER RESOURCES
The planet's water is 97.4% seawater, distributed between the seas, and oceans.
Freshwater, comprising 2.6%, is that which contains total dissolved solids lower than 1000 mg.L-1. Additionally, 1.984% is found in glaciers and icecaps, 0.592% is groundwater, and the remaining 0.015% includes: 0.007% of lentic systems (lakes, ponds and wetlands), 0.005% of soil moisture, 0.001% of atmospheric water vapor, 0.0001% of biota, and 0.0001%
of lotic systems (streams and rivers) (MILLER; SPOOLMAN, 2006).
Streams and rivers have approximately linear and unidirectional variable flow, and unstable beds. Upstream regions usually present high turbulence levels, which increases dissolved oxygen (DO) concentration. At downstream reaches, with higher temperatures, the solubility is reduced, decreasing the concentration of the gas. Another factor that contributes to the reduction of DO is the decomposition of organic matter, which has a high demand for this gas, and can make the environment anaerobic, affecting aquatic life. The distribution pattern of individuals along the river course varies according to factors that mainly involve the relationship between physical variations, chemical composition, riparian vegetation, and disturbance regimes of the riverbed (BRANCO, 1986; BEGON et al., 2006).
2.2 WATER ECOSYSTEMS AND ECOLOGICAL SERVICES
Ecosystems are represented by the relationship of the community with the abiotic environment where it is inserted. The maintenance of the integrity of this relationship guarantees the provision of many ecological services. In general, ecosystems supply a wide variety of goods and services that interest humans directly and indirectly (ARTHINGTON, 2006; MILLER; SPOOLMAN, 2006). Fearnside (2008) groups these services into three main categories: biodiversity, water, and those which avoid global warming. The freshwater systems, even though covering less than 1% of the Earth’s territory, maintain important
ecological, and economic services. Some ecological services are: climate maintenance, nutrient cycling, flood control, groundwater recharge, habitat for aquatic species, genetic and biodiversity resources. Examples of economic services include: food, potable water, water for irrigation, hydropower, transport corridors, recreation, employment, and scientific information. Water resources, as open and complex systems, have their dynamics influenced by physical, chemical and biological aspects. These aspects are represented by the sum of the characteristics of the landscape surrounding them. Climate and geology are of fundamental importance to determining the environmental conditions of this resource (MILLER;
SPOOLMAN, 2006; BUIJS, 2009; GORSKI, 2010; AFONSO, 2011; MOSNER et al., 2012).
2.2.1 Hydrologic Cycle
The hydrologic cycle, driven by the sun, continuously collects, and recycles water (PRESS et al., 2006). The successive changes of the physical state of water induce the movement of molecules in the atmosphere, contributing to the flow of particulate materials attached to water molecules. Each phase of this cycle contributes to breakage, formation and dispersal of particles in the environment (HIRATA, 2000; LEINZ; AMARAL, 2003).
Evaporation occurs when molecules in a water body build up enough kinetic energy, due to solar heating, to eject from the surface. Evaporation also occurs from plant transpiration during photosynthesis, and animal respiration. The main factors affecting evaporation are temperature, humidity, wind speed, and solar radiation (PRESS et al., 2006).
Condensation happens as a consequence of direct cooling (convection, radiation or conduction) or a mixture of air masses with different temperatures. Earth’s average surface temperature, and gravity are determining factors for the occurrence of precipitation (HIRATA, 2000; LEINZ; AMARAL, 2003). There are four pathways which precipitated water can follow: feed rivers, lakes and glaciers; infiltrate the soil and fill underground reservoirs; become part of the biosphere; and evaporate to return to atmosphere. The main variables, which determine the pathway, are: land morphology, vegetation cover, lithology, and soil sealing (KARMANN, 2000).
Heavy rains tend to saturate the soil quickly, creating a large flow of surface water (runoff). Water runoff from the land surface is the portion of precipitation that eventually feeds perennial or intermittent surface streams. Soils with steep slopes accelerate water runoff
and decrease the possibility of infiltration (HIRATA, 2000; PRESS et al., 2006). Low intensity precipitations tend to enhance infiltration, because its rate follows the speed of precipitation (ESCP, 1973; 1976; KARMANN, 2000).
Groundwater feeds rivers and lakes, being responsible for the base flow. Usually, groundwater table is higher than the level of the flow in a river or a lake, developing a pressure head to such an extent that groundwater flows into the body of water; conversely, if the groundwater table is lower, the pressure gradient induces flow into the ground (KARMANN, 2000). On average, the groundwater contribution to the total flow in a basin amounts to about thirty percent of the total (KARMANN, 2000; PRESS et al., 2006). The movement of water under the ground is influenced by gravity, surface tension (capillarity), and the soil porosity (PRESS et al., 2006).
The hydrologic cycle contributes to the natural process of water renewal. However, intensive human activities on a global scale are modifying the chemistry of groundwater and river runoff, leading to increased levels of nutrients and pollutants, such as pesticides, in the cycle (HARBOR, 1994; VRYZAS et al., 2009; KNODEL et al., 2011; OLUKA et al., 2013).
In the case of sodium, chlorine, and sulfate, the increases are as high as thirty percent (OLUKA et al., 2013). The extensive use of fertilizers, herbicides, pesticides, and radioactive products introduces elements that are not natural in the environment, and also cause overload of those naturally occurring (KONSTANTINOU et al., 2006; VRYZAS et al., 2009;
KNODEL et al., 2011; OLUKA et al., 2013).
2.2.2 Elements cycle
Over time and space, the restoration of system balance can occur by the transformation of organic into inert pollutants fostering gradual recovery of the aquatic communities. This process would be sufficient to maintain the quality of water resources in natural conditions, but the exploitation, and extraction activities that cause environmental degradation impair or even prevent the provision of such services (FEARNSIDE, 2008; MILLER; SPOOLMAN, 2006).
Balanced environments tend to have a high diversity of species, with a reduced number of individuals compared with disturbed ecosystems that have low diversity of species, with a high number of individuals (VON SPERLING, 2005). The introduction of polluted substances in the streams modifies the aquatic environment damaging the established
communities. In a polluted environment only the species adapted to the new conditions survive and spread, those which are not tolerant may disappear, reducing the total number of species (VON SPERLING, 2005; SALLA et al., 2013).
In the elements cycle in natural water systems through physical (PALMA-SILVA, 2007), chemical, and biological processes work simultaneously. Some of the factors influencing this process are dilution, currents, temperature (high temperatures increase microorganism activity, accelerating DO consumption), sunlight, and oxidation rate. It is mostly a longitudinal process, and its stages of ecological succession can be associated with four main physically identifiable zones on the river (VON SPERLING, 2005; ANDRADE, 2010), which are shown in Table 1 and Figure 1.
Table 1. Pollution zones in a river or stream (MOTA, 1995).
Pollution zones River flow
Clear water zone Degradation zone
Decomposition active zone
Recovery zone
Clean water zone Dissolved
oxygen sag curve
Saturation level 100%
D.O. 40%
D.O. 0%
Physical Indices
Clear water, no bottom sludge, no color
Floating solids:
bottom sludge present, becoming turbid
Darker and greyish color, generation of gases such as CH4, CO2, H2S and others, lots of sludge coming to the surface forming a scum layer at the top
Turbid with bottom sludge
Clear water with no bottom sludge
Fish presence
Ordinary fish Tolerant fish No fish present Tolerant fish
Ordinary fish
Degradation zone: After receiving pollutants, the water is turbid due to the solids present in the wastewater. Disturbance reduces the number of species, and number of individuals of tolerant species increases. Considering the disposal of domestic sewage, with predominance of organic matter, microorganisms present in the wastewater are responsible
for decomposition. After the period of microbiological adaptation, the rate of consumption of organic matter, and DO reaches its maximum. At this stage, there is an increase in carbon dioxide levels (as a byproduct of microbial respiration), which in aquatic environments is converted into carbonic acid and may reduce the water potential of hydrogen (pH). At the bottom sludge, due to the difficulty of gas exchange with the atmosphere, the environment becomes anaerobic, and microorganisms increase the production of hydrogen sulfide, causing foul odor (LEITE et. al., 2001). The complex nitrogenous compounds present in high concentrations are gradually converted into ammonia (VON SPERLING, 2005; ANDRADE, 2010).
Decomposition active zone: In this phase the microorganisms actively decompose organic matter, and water quality has its maximum level of deterioration. DO reach its lowest concentration, often going down to zero. The decomposing bacteria begin to reduce in number due to decreased availability of food (most of it already stabilized). Anaerobic organisms predominate, and by-products of the reactions include: carbon dioxide, methane, hydrogen sulfide and mercaptans. Nitrogen is still found in organic form, mostly in the form of ammonia. At the end of this zone, an increase in DO concentration oxidizes ammonia to nitrite. Thus, the number of protozoans rises and some macro-invertebrates and insect larvae are present (VON SPERLING, 2005; ANDRADE, 2010).
Recovery Zone: The turbidity of water decreases, deposits of silt settle to the bottom, which exhibits a grainy texture, with low release of gases and odors (LEITE et. al., 2001).
Organic compounds are stabilized (transformed into inert compounds). The consumption of oxygen by bacterial respiration is reduced, which together with the introduction of atmospheric oxygen into the liquid mass, increase the DO levels. Ammonia is converted into nitrite and nitrate and phosphorus is transformed into phosphate. These compounds fertilize the environment, which together with the reduction of water turbidity (allowing light penetration) fosters algae growth. Further, this process increases DO levels, through photosynthesis, and contributes to the diversification of the food chain. Thus, the number of bacteria and bacteriophage protozoans is reduced, algae reach high reproduction indices, nurturing crustaceans, worms, dinoflagellates, sponges, mosses and insect larvae, which serve as food for the most tolerant fish (VON SPERLING, 2005; ANDRADE, 2010).
Clean water zone: It is characterized by high ecological balance and good water quality. In the liquid mass, mineral compounds are predominantly oxidized and stable, while the bottom sludge metals may not be fully stabilized. The oxygen concentration is close to
saturation due to low consumption by the microbial population and the production of gas by photosynthesis performed by algae (VON SPERLING, 2005).
Figure 1. Types of organisms in the clean zone and pollution zones (GARRISON, 2011).
2.2.3 Riparian zone
Riparian zones are delimited by the depositional substrate of the waterway. Forests are responsible for regulating the water regime, protecting water bodies against erosion, maintaining water quality, controlling soil stability, nutrient cycling, and rainwater runoff (ASANO, 2006; PEDERSEN et al., 2007). They also control the growth of aquatic macrophytes, support aquatic organisms and waterfront wildlife. Riparian zones often harbor high numbers of vascular plants and bryophytes, beetles, birds, mammals, and other animals (KUGLEROVÁ et al., 2014). They act as a buffer system for filtering polluted air sediments, nutrients and pesticides (ANBUMOZHI et al., 2004).
The specificity, magnitude and importance of services provided by riparian zones depend on particular characteristics of the regional properties, including climate, bedrock characteristics and landscape formation history. It is being increasingly recognized that the riparian functions vary among individual basins as well as among segments of individual rivers. The heterogeneity of riparian zones at spatial scales needs to be better recognized in landscape management (KUGLEROVÁ et al., 2014).
Riparian zones perform fundamental functions but nonetheless they represent one of the most degraded ecosystems worldwide (NILSSON; BERGGREN, 2000). Causes of riparian zone degradation include disturbances in upland areas and changes in the river
regime. Changes in river morphology, such as those caused by river channeling and dam construction, change the riparian dynamics. Industrial, livestock and forestry activities in upland areas can cause losses and changes in the composition of species in riparian and aquatic habitats (NILSSON; BERGGREN, 2000; FEARNSIDE, 2013). They can also change stream-water chemistry (BISHOP et al., 2009), increase siltation, and alter hydrology (ANDRÉASSIAN, 2004).
The restoration and maintenance of structure and function of riparian ecosystems has become an international topic of concern since the presence and balance of these systems help control flood magnitude and frequency, and channel forming. Improvement strategies to prevent and mitigate the impacts of forest management must be central to sustaining the functions of riverine ecosystems. At the same time, these methods have to balance the needs of forestry and conservation, with ecological benefits weighed against economic issues (SLOAN, 2001; PEDERSEN, 2007). It was evidenced that in cases of reforestation of riparian areas, a time lag may occur in the functional maturation in terms of the nutrient and pollutant removal. In these cases, it is recommended to develop a multi-purpose buffer design, which consists of strips of grass, shrubs, and trees between the standard bank-full water level and cropland or impact zone. The benefits of this system include bank stabilization, improvement and protection of the aquatic environment, and protection of cropland from erosion and flood debris damage. Grass disperses and slows runoff from adjacent crop fields, which promotes sediment settling and infiltration of nutrients and pesticides, which are taken up by growing vegetation and soil microbes. Perennial vegetation provides wildlife habitat and visual diversity to the landscape cropland (ANBUMOZHI et al., 2004).
Since they are located between aquatic and terrestrial environments, the riparian zones are also named as transition zones, which vary in size and may include swamps, marshes, potholes prairie, and wetlands. Wetlands occur in water exchange zones are influenced by flooding and groundwater levels. Many of these areas may remain dry for years until water covers them again. The flow of water through the roots, leaves and stems of plants, may induce nitrification and denitrification processes (BISHOP et al., 2009). This system plays important roles, such as filtering pollutants, absorption and storage of excess water from storms, banks stabilization, thermal balance, formation of ecological corridors, as well as provision of habitat for many species (VAZ; SARAIVA, 2007; AFONSO, 2011; ARLETTAZ et al., 2011).
2.3 WATER QUALITY
2.3.1 Quality criteria in fresh water
Quality evaluation requires the distinction between substances that endanger or poison aquatic organisms, and substances that affect primarily the organization and structure of aquatic ecosystems. Contaminants may impair the self-regulatory functions of the system or also interfere with food chains, altering local distribution (STUMM; MORGAN, 1995).
2.3.2 Classification of freshwater quality
The quality of water in rivers and streams determines the possibilities of use and exploitation of the resource. In Brazil, CONAMA Resolution 357/05 (BRAZIL, 2005), establishes the framework for freshwater resources quality, defining five classes of water quality:
Special Class: after simple disinfection, this water can be destined for human supply. It is also intended to preserve the natural balance of aquatic communities and the conservation of aquatic environments in conservation units.
Class 1: water intended for domestic supply after simplified treatment, protection of aquatic communities, primary contact recreation, agriculture irrigation for human consumption;
Class 2: water intended for domestic supply after conventional treatment, protection of aquatic communities, primary contact recreation, irrigation of plants and vegetables;
Class 3: water intended for domestic supply after conventional treatment, irrigation of tree crops, grain and forage and watering livestock;
Class 4: water intended only for navigation and landscape harmony.
2.3.3 Water Quality Index
The Water Quality Index (WQI) is used to standardize the interpretation and dissemination of information on water quality and to indicate the treatment to be used. This value is calculated as the weighted product of nine selected parameters among the indicators
of water quality, which are: temperature, pH, dissolved oxygen, biochemical oxygen demand (5 days, 20° C), fecal coliforms, total nitrogen, total phosphorus, total residue and turbidity (CETESB, 2008).
2.3.3.1 Temperature
The natural climate regime changes the temperature of the water affecting physical, chemical and biological processes. A decrease in water temperature reduces the thermal agitation of the molecules and increases the number of hydrogen bonds, resulting in increased density of water. An increase in temperature decreases the solubility of oxygen in water, and enhances the solubility of various chemical compounds, which may increase the deleterious effects of pollutants on aquatic life (PALMA-SILVA, 1999).
2.3.3.2 pH
The pH is an important parameter that directly influences the chemical balance. It is related to the concentration of H+ and OH- ions. The presence of salts, acids and bases influence pH values. Protection of aquatic life limits pH values between 6 and 9. Extreme values can affect water treatment processes, in addition to contributing to the corrosion of hydraulic structures (CETESB, 2008).
2.3.3.3 Electrical conductivity
Water conducts electricity because it contains many dissolved ions, which have electric charges. The electrical conductivity of water is directly proportional to the concentration of dissolved solids and can also indicate its composition. In natural surface waters it varies between 50 and 1500 μS.cm-1, while in industrial wastewater this parameter may be higher than 10000 μS.cm-1. The water supplied by municipal water providers usually contains ions Cl-, H+, and many others depending on the treatment process (CETESB, 2008).
2.3.3.3 Dissolved Oxygen (DO)
Dissolved oxygen refers to the molecular oxygen (O2) dissolved in water whose concentration depends on temperature, atmospheric pressure, salinity, biological activity, hydraulic characteristics, and biochemical variations. These changes are caused primarily by
the oxidation of organic matter discharged into streams as soil wash and waste. In the presence of an oxygen supply, together with certain oxidizing bacteria and oxidizable organic matter, progressive oxidation and stabilization of the organic matter take place. It has been shown that, under experimental conditions approximating those prevailing in a stream containing reserve DO, this reaction is an orderly and consistent one, proceeding at a measurable rate and according to the following definite law: The rate of biochemical oxidation of organic matter is proportional to the remaining concentration of unoxidized substance, measured in terms of oxidizability (STREETER; PHELPS, 1958; VON SPERLING, 2005). The average oxygen concentration in the atmosphere is 270 mg.L-1, while in water, under normal conditions of temperature and pressure, its saturation concentration is approximately 9 mg.L-1. According to Pinto et al. (2010) most species cannot live in DO concentrations below 4 mg.L-1. The aquatic environment is very sensitive to changes in DO, with its availability quickly reflecting any changes in consumption and production, which allows the use of DO as an indicator of the degree of pollution and depuration in watercourses (VON SPERLING, 2005).
2.3.3.4 Turbidity
Turbidity of water is mainly attributed to the solid particles in suspension, which reduce the transmission of light. This fact can be caused by the presence of plankton, algae, organic debris and other substances such as zinc, iron, manganese and sand, resulting from natural erosion and runoff or human action, such as the release of sewage and industrial activities effluents. High turbidity affects the development of aquatic life, mainly due to the impairment of light penetration, inhibiting photosynthetic processes (CETESB, 2008).
2.3.3.5 Total solids
In natural waters dissolved solids are mainly composed of carbonates, bicarbonates, chlorides, sulfates, phosphates, nitrates, calcium, magnesium and potassium. The minerals contained in natural waters can be increased by addition of anthropic waste (CETESB, 2008).
2.3.3.6 Nitrogen (N)
Nitrogen is considered one of the most important elements in the metabolism of aquatic ecosystems. It is important to keep it balanced, since low concentrations can limit
primary production, while high loads of nitrate encourage the proliferation of microorganisms, and even present potential toxic threat to aquatic organisms. In degradation processes, nitrogen compounds are formed, such as ammonia, ammoniacal nitrogen, nitrite, and nitrate. Nitrate is present in most surface waters and originates from human, animal and fertilizer sources, and thus can reflect the condition of water sanitation. Ammoniacal nitrogen is composed of the sum of ammonia (NH3) and the ammonium ion (NH4+
), present naturally in low levels in surface and groundwater, and resulting from the decomposition of organic matter, with high levels indicating domestic or industrial pollution (BRIGANTE et al., 2003).
2.3.3.7 Phosphorus (P)
Phosphorus originates from natural sources such as rocks in the drainage basin, particulate material, decomposing bodies and artificial sources. Sewage and agricultural surface runoff are examples of artificial sources, which carry fertilizers and derived chemical compounds. Inorganic phosphate is the main form of phosphorus available to aquatic plants, and its concentration varies with the pH (ESTEVES, 1998).
2.3.3.8 Fecal coliforms
The microbiological quality of water is determined by assessing water samples for the presence of bacteria indicative of fecal contamination from total coliforms and Escherichia coli (E. coli.). Thermotolerant coliforms occur naturally in soil and in the bowels of humans and other animals, thus, their presence in water may indicate fecal contamination. E. coli. are present only in the bowels of humans and animals, thus, their presence in drinking water indicates definite pollution (TORTORA, 2000; OLUKA et al., 2013).
2.3.3.9 Biochemical Oxygen Demand/ Chemical Oxygen Demand (BOD/COD)
BOD and COD are used to measure the organic matter content in the water through oxygen consumption. BOD indicates the amount of oxygen required to oxidize the organic matter by aerobic biochemical processes leading to stabilized inorganic forms. BOD is usually referred to in terms of the amount of oxygen consumed in an incubation period of 5 days at 20ºC (BOD5). The BOD is an appropriate parameter for evaluation of the influence of domestic, agricultural and certain industrial processes that degrade water quality. Chemical
oxygen demand, COD, indicates the oxygen level required for the chemical oxidation of organic matter in the water. COD constitutes an estimate of the amount of organic matter and other reducing agents present in the water. This parameter can also indicate the occurrence of water pollution because it includes organic compounds from hard biological decomposition (CETESB, 2008).
2.3.4 Sediment
Sediment is a product of weathering, the relocation and reorganization of the upper layers of the earth's crust under the action of the atmosphere, hydrosphere, biosphere and energy exchanges involved. It can also originate from mechanical and biogeochemical disintegration of rocks by tectonic stress and the translocation of these products as gravity driven mass flows or by fluid driven erosion agents (rivers, ocean currents, wind, and glaciers). In aquatic ecosystems the composition of sediment is influenced by physical, chemical and biological processes, which create a highly diverse environment where organics and solutes strongly rely on the behavior of transporting fluids and gravitational processes (LOMBARDI et al., 2005; MANAHAN, 1994; SILVERIO et al., 2005).
From the ecological point of view, more than providing habitat for aquatic organisms, sediment also acts as source and sink of organic and inorganic matter, serving as a reservoir for bioaccumulation and transference between trophic levels. Sediment can be incorporated into natural environments by microorganisms, decomposition of animal remains and anthropogenic sources. Some processes influence removal and suspension of these materials (LOMBARDI et al., 2005).
Sediment analysis can be used to detect the presence of contaminants that remain soluble after release into surface waters. The sediment is distributed in layers that enable the assessment of its quality, provide information about the water column contamination, and can also provide a historical record of the aquatic environment (BAIRD, 2002). In order to know if the contaminants detected in the samples have adverse effects on the biota it is recommended the analysis of chemical (concentration of metals and organic compounds), physical (pH and particle size), biological (zoo-benthos), and eco-toxicological parameters (toxicity test and mutagenic test) (CETESB, 2005).
The mobilization of chemical elements in lakes and reservoirs depends on the nature of the contaminant and the characteristics of the system such as flow, thermal stratification
and mixing, which define, for example, the speed, and direction of contaminated parts. The concentration of chemical elements in the sediment depends on the size and composition of the grains, being higher in clay, and lower in sand (MANAHAN, 1994; SILVERIO et al., 2005).
The discharge of industrial and domestic effluents, among other pedogenic processes, change the settling dynamics found in undisturbed natural environments (STUTTER et al., 2007). Heavy metals are an example of industrial effluents, as non-biodegradable contaminants that remain in global biogeochemical cycles. Water courses are their main way to be incorporated in the biota, accumulated and transferred over the trophic network (bio- accumulation and bio-magnification), or remain biologically unavailable as insoluble, stable, and refractory complexes. Organic Matter (OM) performs an important role in controlling the bioavailability of metals (LOMBARDI et al., 2005). Microorganisms also affect metal speciation and bioavailability, producing dissolved organic matter, and also possessing binding sites in their plasma membranes (STUTTER et al., 2007).
Suspended particulate material (SPM) is ubiquitous in most aquatic systems. SPM loads are influenced by land use factors, such as soil erosion associated with agriculture, or by internal processes such as biological organic matter cycling. The effects of SPM on river ecology are complex and can include inter-relationships between grazers, siltation of habitats, and effects of reduced light penetration on photo-synthesizers (BAIRD, 2002). Increasingly, studies are focusing on the quantification of heavy metal pollution in sediments, gathering data on the associated environmental impacts and their complex relationship with economic activities (STUTTER et al., 2007).
2.3.4.1 Siltation
Anthropogenic activities synergistically intensify the process of erosion and silt production. Moreover, soil erosion leads to off-site effects such as the siltation of lakes, reservoirs, and rivers (CHETTRI, 1983). Excessive and uncontrolled siltation is a major problem in many reservoirs and other projects on waterways. While siltation is a naturally occurring phenomenon and must be taken into account during the planning of a project such as a reservoir, it becomes a cause for concern when caused by anthropic activities. Siltation has its greatest economic impact in the filling up of reservoirs. With the reduction in storage capacity, the ability of dams to control floods is diminished, which can result in high damage
costs due to flooding. High siltation is often a result of poorly managed watersheds, together with improper land-use patterns. Overgrazing, deforestation for firewood and intensive cultivation even of steep slopes all result in erosion and loss of valuable topsoil. In developing countries, where there is great dependence on agriculture and where topsoil loss can least be afforded, the problem can be critical. Agriculture is associated with non-point source inputs into water bodies of nutrients, and enhanced soil erosion. Streams in agricultural areas also tend to have impaired habitats (HAUER, 2015) due to loss of riparian woodland, stream straightening, increased bank erosion, and accumulated fine sediments in pools (ALLAN, 2004).
2.4 SOCIETY AND RIVERS
Anthropogenic processes exert significant influence on the water resources. They are variable in time and space, which usually causes pollution, resulting in quantitative and qualitative degradation, affecting the dynamics of nutrient cycling and energy flow (BISWAS, 1996; BLACK, 2004; POMPEU et al., 2005; MILLER; SPOOLMAN, 2006; BEGON et al., 2006; GORSKI, 2010; AFONSO, 2011). Thus, in order to understand the causes, identify the sources of pollution and imbalance of water systems, it is important to consider the historical relationship of man and rivers.
The presence of water in the landscape influences society in cultural, mythological, historical, literary, artistic and even religious aspects. The majority of ancient civilizations utilized the proximity of water to establish their villages, either for functional, strategic or heritage reasons (BISWAS, 1996; DIAS, 2004; BEGON et al., 2006 e GORSKI, 2010).
Human history can be considered water-centered in terms of interactions and interrelations between people and water. This mode of social development has a direct influence on the quality of this resource (BISWAS, 1996; BEGON et al., 2006; GORSKI, 2010).
The first reports of relationships between humans and rivers date back to 6000 BC. At that time the settlers of Mesopotamia (Sumerians) began a new way of growing food by constructing ditches, which diverted water from the Euphrates River, irrigating crops. In 4000 BC the agricultural villages in the Mesopotamia river valleys became the first cities in the
world and also the most powerful society due to their control of rivers Tigris and Euphrates (DIAS, 2004; ASANO et al. 2006).
2.4.1 Influence of society on water quality
Consequences of this relationship between society and environmental resources could be noted since the beginning of the Greek and Roman Civilizations, when garbage disposal became a major problem. The waste, feces and urine were deposited on the streets and through the rain were dragged to the water bodies. In 320 BC the Greeks created a law prohibiting the release of garbage on the streets, but this pollution control declined after the fall of these civilizations, and the streets again became the main destination of waste.
Attempting to resolve the problem, the profession of garbage collectors was made official in all the British cities in 1714. The sewage began to be deposited in underground reservoirs, causing contamination of drinking water. Then, in order to avoid this problem, it started to be transported to the water bodies by a system of pipes in England and the USA (BEGON et al., 2006).
During the 18th century the development of industrial cities worsened the pollution of rivers in North America. Throughout the 19th and 20th centuries, industrial processes created a variety of pollutants that were not part of the prior composition of rivers. They significantly increased the amount of contaminated material deposited in waterways, thereby causing an overload in the depuration process (HOLM et al. 2012). In many rivers, chemicals such as acids, pesticides and heavy metals have accumulated in sediments and through the food chain expanding by bio magnification (BEGON et al., 2006).
In the European Community, the activities of deforestation and tillage caused siltation problems due to changes in sediment transport. Reports from the medieval age and from the time of the Roman Empire confirmed irregularities in sediment deposition, which resulted in the development of channels. The 11th century was marked by the construction of dams used for flood control and land reclamation. The purpose of all hydraulic works involved maximizing the use of water resources only to raise economic productivity ignoring environmental issues (TOCKNER et al., 2009; MERLO, et al., 2011).
Brazil holds one of the longest and richest networks of perennial rivers in the world, for its prevailing geological and climatic conditions, with a large territory, geographically located in a humid strip of land, between the Tropic of Capricorn and the Equator.
Approximately 11.6% of the surface freshwater in the world is in Brazil, 70% of which are located in the Amazon Basin and are threatened due to deforestation in this region (FEARNSIDE, 2008; GORSKI, 2010). Since the beginning of the twentieth century until the 1930s, the model adopted for the protection of water resources in Brazil was the total preservation of watersheds, which contributed to protecting water supply sources. However, high costs of expropriations and demand for land have made this policy unfeasible. During this period, water management occurred at the federal level through the National Department of Agriculture, because of the predominant agricultural production of the country. From the 1990, when industrialization began to predominate, water management policies favored the exploitation of the energy potential of river systems (GORSKI, 2010).
The city of São Paulo, in Brazil, is an example that illustrates how infrastructure development can alter water resources. São Paulo is strategically positioned around watercourses, which were responsible for the sustained life and growth of the original village.
High economic growth based on coffee export made the city a strategic point in the state.
The village evolved into an urban configuration that demanded transportation, factories, schools, hospitals and others services, which required a larger electricity supply that led to the construction of dams to produce hydropower. In conjunction with this movement, in 1867 the main railroad was opened which was built along the Tamanduateí river, strengthening a strategic position of the city as meeting point of several railroads. The magnificence of the machines changed life in cities and put the society away from nature and, little by little, rivers that were the reason for the existence of the city had become obstacles to their growth. To ensure the success of city development projects, in 1878 the first water supply system was created. Due to this, river curves were cut off, riverbeds sunken and water bodies channeled and covered by avenues, the water giving space to motor vehicles (GORSKI, 2010; ALMEIDA, 2010).
Industrial growth also caused strong changes in the urbanization patterns, demanding the development of new areas and the retrofitting of existing ones, increasing their financial value (GORSKI, 2010; ALMEIDA, 2010).
Thus areas subjected to flooding “only once a year” were deemed interesting for housing developments, adding to the problem of flooding, and leading to the reclamation and destruction of flood plains for human occupation. This characterized the urban land as a commodity, not as a living space to interact with nature. Lack of a metropolitan housing policy, lack of inspection, increasing unemployment and decreasing investment in social
policies, forced the poorest population to move to the outskirts of the city, putting even more pressure on the environment, endangering water quality, and compromising the preservation of the local ecosystems (GORSKI, 2010; ALMEIDA, 2010).
Watershed occupation was further accentuated along roads and highways that cut the springs as a result of population growth, followed by a housing shortage for low-income families, who purchase “affordable” lots, with no guarantee of legal rights, improper infrastructure, but allowing them the right to housing (GORSKI, 2010; ALMEIDA, 2010).
The largest cause of pollution in the Billings reservoir, the main water source for the city of São Paulo, is poorly planned land occupation in the corresponding river basin. Besides the issue of untreated sewage in the Alto Tietê basin, the presence of foam surfactants in the Tietê River, the formation of algae bloom that impair water quality, the clearing of remaining forests and irrational land use exceed the environmental carrying capacity of the watershed, affecting multiple uses of the reservoir and impairing use of water resources for energy production (ALMEIDA, 2010).
The Atlantic Rain Forest in the region of the Billings reservoir shelters large industrial enterprises attracted by the good road infrastructure. This favors only regional economic success without considering the capacity of the reservoir to absorb the impacts and maintain water supply for consumption and energy generation. The Henry Borden hydroelectric plant became a victim of urban growth, which it supported (ALMEIDA, 2010).
This framework causes environmental impacts, which reflect a disorganized urban expansion process. It is fundamental to restrain illegal occupation in any area around the floodplains as the exposure of soils in a watershed causes the entrainment of solid particles into the body of water, reducing the storage capacity of reservoirs (ALMEIDA, 2010).
2.4.2 Brazilian environmental sanitation
The situation in Brazil is not exactly related to scarcity but inefficient management of development in general and waters in particular, both by public and private entities. National public actions are geared towards structural measures, such as channeling watercourses without assessing the consequences, which actually increase the flow and frequency of flooding, mainly in medium and large cities. Management continues to be an unresolved issue that affects the sanitation of the country (GORSKI, 2010).
Polluted water and inadequate sanitation in developing countries are responsible for about 88% of diseases and 33% of deaths, particularly affecting the infant population and burdening healthcare systems (WHO, 2006). Inadequate sanitation, hygiene and lack of access to water increase the incidence of diarrheal diseases, which are the second cause of death among children from zero to five years old. It is estimated that each year 1.5 million children in this age group die of diarrheal diseases worldwide. In 2011 in Brazil, 396.048 people sought health care with diarrheal diseases. Of this total, 50% were children in this age group (which is the most weakened by the lack of sanitation). This rate is higher than 70% in some Brazilian cities such as Duque de Caxias (RJ), Juazeiro do Norte (CE), Macapá (AP), Feira de Santana (BA), Belém (PA), Porto Velho (RO) and Manaus (AM). The expenditures of the health system with hospitalizations for diarrhea, in 2011, amounted to nearly US$ 70 million. The municipalities with higher spending were precisely those with the worst health and sanitation indicators (TRATABRASIL, 2013).
Evidencing this, Vorosmärty et al. (2010) correlated incident threats to human water security (HWS) and biodiversity perspectives within a spatial accounting framework and created maps of incident threat. These maps were based on four themes: catchment disturbance, pollution, water resource development and biotic factors, representing environmental impact, in a scale varying between 0 (mildly affected) and 1 (impacted strongly).
General results showed that in 2000 nearly 80% of the Earth's population lived in areas where the HWS and biodiversity threat were above 0.75. Considering the forty seven longest rivers in the world, more than thirty had threat levels above 0.5, including eight rivers for HWS, and fourteen rivers for biodiversity, which showed levels of threat greater than 0.75. In 2008 China had around 45% of its main rivers classified as moderately to badly polluted, and around 65% of the global aquatic habitat was under moderate to high threat (>0.5) (VOROSMÄRTY et al., 2010).
Further information reveals the intense anthropogenic intervention on water resources quality: the comparison between eastern and western China rivers showed that even with higher dilution capacity and greater rainfall; eastern rivers have higher incident threats than those in the arid west. The sparse population and limited economic development in the western region attenuate the impact, while the higher population and higher rates of development in eastern China render the rivers unable to recover from the impacts of concentrated pollution (VOROSMÄRTY et al., 2010).
High levels (>0.75) of incident threat for HWS (Human Water Security) and BWS (Biodiversity Water Security) are associated with pollution and catchment disturbance, while water resource development and biotic factors, as localized effects, play secondary roles in high incident threat areas. Impoundments and flow depletion are the strongest stressors for biodiversity threat because they directly degrade the native habitat. These differences between the main stressors for HWS and BWS need to be considered one by one, in order to ensure the success of management programs, which aim to solve these issues. Furthermore, misguided efforts and investments are often applied in technologies to treat water for human consumption, reducing incident threats. In this way, however, what are being treated are symptoms instead of causes of incident threats. Additionally, technology investments tend to benefit wealthy countries only, while areas with limited investment capability remain vulnerable (VOROSMÄRTY et al., 2010).
2.5 CAUSES OF WATER RESOURCES DEGRADATION
Water stressors can be classified as point and nonpoint pollutants. The current economic system dumps pollutants both ways (Figure 2). Point sources are emissions released in one specific location: sewage discharges, industrial effluents and emissions. Nonpoint pollutants are not confined to a single location and may reach a water body from polluted air, water and sediment. Some authors claim that volatilization and transport through the atmosphere are the most important mechanisms of pollutant dispersal (STUMM; MORGAN, 1995; BAIRD, 1995; MILLER; SPOOLMAN, 2006), followed by runoff. The precipitated water is mixed to urban runoff, automobile traffic, livestock wastes, fertilizer and pesticides (MILLER; SPOOLMAN, 2006). The contaminants are leached as part of the flow to the groundwater. This process are aggravated by deforestation, improper land use, and by the dispute between the users represented in various sectors of industry, agriculture and sanitation (ANDREOLI et al., 2000).
Worldwide, 70% of water extracted from rivers, lakes and aquifers are designated to crop irrigation. Industry uses 20% and the cities and houses use the remaining 10%
(MILLER; SPOOLMAN, 2006).
