Environmental Health Implications of residential development on urban wetlands


Historically, the concept of urbanization has been related to specialized industrialization and consequent economic development. Urbanization is a territorial response to structural changes in the economy. Unregulated and unguided urbanization has its own problems as evidenced in the deteriorating environmental conditions of many large cities. Sustainable urban settlements have to be environmentally sound, economically efficient and socially contributing to the sense of the community. Urbanization is a major cause of impairment of wetlands and has resulted in direct loss of wetland acreage as well as degradation of wetlands.  Wetlands were defined at Ramsar Convention 1971 as “areas of marsh, fen, peat land or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salty, including areas of marine water the depth of which at low tide does not exceed six meters”. This definition was further expanded to include a variety of natural systems, such as marshes, swamps, bottomland hardwoods and pocosins (DCM, 2007)

The Kenyan definition of wetlands is “areas of lands that are permanently or occasionally water logged with fresh, saline, brackish or marine waters, including both natural and man-made areas that support characteristics biota”. Wetlands act as sources and reservoirs of water resources. They recharge and discharge water, hence playing an important role in the water cycle. Wetlands cover less than 9% of the earth’s land surface, but provide habitat to disproportionately high numbers of species, such as water birds, amphibians, fish, invertebrates and variety of flora. Wetlands also offer ecosystem services such as water purification, flood control, nutrient cycling and carbon sequestration.

Wetlands are among the most productive ecosystems due to their functions and attributes. However, over the years they have faced destruction and are on the verge of distinction. The international community realized this outcry and the effects it would have to flourish on human and therefore converged in Ramsar, Iran to come up with Ramsar convention on wetland protection.

The Ramsar Convention raises concern that many wetlands in urban environments are becoming and are, degraded through encroachment of surrounding populations, pollution, poor waste management and infilling or other developments, hence these activities have diminished both the ecosystem services that urban wetlands can provide moreover the recognition of their value and importance by both decision makers and urban communities.

Globally wetlands occupy about 6% of the earth’s surface and this ranges from 5.3% to 12.8% million km2. Kenya’s wetlands occupy about 3-4%, which is approximately 14,000km2 the land surface and fluctuates up to 6% in the rainy seasons. However, due to high rates of wetlands and catchment degradation, the total percentage of wetlands area is estimated to be below 2% (GOK, 2008).

Wetlands are essential to the wellbeing of humans as they contribute significant economic and social benefits to man. Despite their high productivity and provision of many benefits, wetland ecosystems are still facing serious threats. They are subjected to encroachment and exploitation because of their resilience to extended drought thereby making them the main source of water for drinking and irrigation. This is the impacts of encroachment of wetlands worldwide.. The effects are more in the urban areas due to the rapid urbanization that is estimated at an annual growth rate of 1.6%.

Many wetlands have continued to experience an array of pressures and threats emanating from both the natural events and anthropogenic activities as 80% of wetlands occur on lands, which are privately or communally owned, and without any serious conservation measures.

Wetlands are considered as fragile ecosystem and are highly vulnerable due to anthropogenic activities (settlement, agriculture). In the past, wetlands have been regarded as “wastelands”, which harbor disease vectors. This has led to large-scale drainage and conversion for alternative uses without giving regard to ecological and socio-economic values.

A negative perception of wetlands as “wastelands” coupled with increasing human populations and changing lifestyles has led to the loss and degradation of wetlands through conversion into other land uses such as agriculture, pastureland, fish farming and residential areas, that are perceived to be more profitable. Urbanization of areas surrounding a wetland frequently has serious consequences for the ecosystem. Any development upstream and in some instances downstream, can negatively impact a wetland’s function. Wetlands provide many ecological benefits such as pollutant removal, flood attenuation, ground water discharge, shoreline protection, recreational areas and support of natural resources. Typically, the cost of replacing a natural wetland is greater than the benefits obtained by developing it.

Several wetlands are under increasing pressure and in the process of losing many of their important functions, with serious consequences of changed water regimes, significant conflicts over resource use and loss of livelihood opportunities. Many wetland areas experience a rapidly growing population with poor people moving into the areas in search of livelihood opportunities leading to a strong economic pressure of conservation of wetlands to other functions and only limited considerations are given to the sustainability of changes. The Millennium Ecosystem Assessment (MEA) reported that the degradation and loss of wetlands, and the deterioration of freshwater and coastal wetland species, are more rapid than that of other ecosystems (World Resources Institute, 1995). Planning of land and resource use in wetlands is limited and furthermore plans are seldom put into practice, Coordination of the activities taking place on the ground in the wetlands is exceedingly difficult and the skills for undertaking wetland management are insufficient. The knowledge base about wetland resources, status and key management problems is limited and no proper policy guidance is in place.

Impacts of Urbanization on wetlands

The increased burden of urbanization threatens the quality of air and water, thereby impacting the natural and living environment. The hypothesis that urbanization can have direct or indirect impacts on the environment, and that wetlands are particularly susceptible to negative change, has long been proven. Yet despite this, the much of urbanization continues to destroy and degrade natural capital.

a. Direct impacts on wetlands

These include development of wetlands for the purposes, which often involve dredging, filling and draining the area, and are altered by activities occurring inside the wetland boundary. Examples include draining wetlands for agricultural use by constructing drainage ditches or installing underground drainage tiles and filling wetlands to provide useable land on which to build.

To facilitate city development rapid and unplanned land reclamation has been achieved by infilling swamps and floodplains. Not only has this impacted directly on wetland biodiversity, destruction of forests and wetlands has reduced the flood storage capacity of the land resulting in increased flooding. Experts noted that while economic activity and urban development often increase the environmental pressures that lead to flooding, it is usually the low income settlements and poorest groups within the urban settlements that tend to be the most vulnerable.

The relatively flat terrain associated with river floodplains and estuarine wetlands is easier to urbanize than upland areas, resulting in a concentration of human developments on these habitats. This has resulted in a progressive direct loss of coastal and floodplain wetlands around the globe, through activities such as drainage or infilling, and indirect degradation, through activities away from these areas such as water abstraction or conversion of wetlands to agricultural and settlement lands.

Researchers estimate that 105.5 million acres of wetlands were present in 1997. Historically, most wetland loss has occurred in freshwater wetlands.

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b. Indirect impacts on urban wetlands

These originate outside of the wetlands through the alteration of the hydrological system. Hydrologic changes through land development compound as vegetation is removed, which intercepts rainfall, the soil is compacted, impervious surfaces are created and drainage systems are installed. This creates hydrologic stressors of increased ponding (alters the ecosystem and paves way for invasive species that can adapt to new conditions), increased water level fluxuation (as a result of impeded buffering of storm runoff creating acute flood hazards and greatly impacting the stability of water ways and emergent habitat), flow constrictions (they can fill with sediments reducing the flow volumes across barriers limiting linkage between upstream and downstream), decreased ground water discharge ( through impervious structures and storm sewer systems) and hydrological drought that is brought about by channel deepening which occurs during episodic high discharge events.

c. Cases of wetlands loss

The US national wetland inventory provides a wealth of details on the quantities scale of wetland losses by region, by type and overtime. An analysis of the wetland losses between the 1970s and the 1980s indicates that 53% loss occurred in the conterminous U.S (Judith, 2007; DCM, 2007). The least impact has occurred in the Alaska where the states massive 170 million acres of wetland resources have only suffered only 1% loss. Next lowest losses occurred in Hawaii (12%), New Hampshire (9%) and Rhode Island (37%). Ohio and California have lost most at 90% and 91%, respectively (Judith, 2007).

In Canada, high level of quantitative information on losses of wetlands is available. In a study carried out by the National Wetlands Working Group in 1988, it was observed that 65% of Atlantic tidal and salt marshes, 70% of the lower Great Lakes-St Lawrence River Shoreline marshes and swamps and 80% of pacific coast estuarine wetlands are estimated to have been converted to other uses. Primarily, this is due to agriculture drainage, urban and industrial expansion to construction of road ports and hydroelectric facilities and increased demand of recreational facilities.  In Europe, the most recent overview of the extent of wetland loss indicates that overall wetland loss exceeds 50% of the original area (UNEP, 2005). This is reported in areas like Netherlands, Germany, Spain, Greece, France, Italy and parts of Portugal (Judith, 2007).

The situation concerning wetland losses in Africa is characterized by an extreme paucity of published quantitative studies. This may reflect both generally lower rates of wetland losses than in industrialized regions, but also the lack of capacity to undertake the studies in many countries. For example, in a review of wetland inventories in South Africa gives some information is given regarding the extent of wetland resources in 10 countries in the region. Loss figures are given for Natal-the Tugela Basin, where over 90% of the wetland resources have been lost in parts of the basin; and the Mfolozi catchment where 58% of the wetland has been lost. The other is that of the wetland inventory of Tunisia which reports an overall loss of 15% of wetland area.

Policy and Legal Framework

This section focuses on the policies and legislative frameworks that relate to the conservation, protection and management of wetlands both internationally and nationally.

a. Ramsar Convention on Wetlands

The Wetland or “Ramsar” Convention is the oldest of the global nature conservation treaties, and the only one that is dealing with a particular ecosystem.

This is the only global environmental treaty that is associated and deals with the environment. It is an intergovernmental treaty that provides the framework for national action and international cooperation that provides for the conservation and sustainable use of wetlands and their resources through local, regional and national action.

The Convention was signed in Ramsar, Iran on 2nd February 1971, and came into force in 1975. To date, there are 168 Contracting Parties to the Convention up from 119 in 1999, with now 2,122 wetland sites known as Ramsar sites covering 205,366,160 ha (507,470,800acres) up from 1,021 sites in 2000.

Its objective is to protect and conserve a particular ecosystem and the flora and fauna that depend on it. The key obligation is to are those concerning land-use planning, the designation of one or more wetlands for inclusion in the “List of Wetlands of international importance” and their conservation and finally the promotion of the protection of wetlands in general.

In the sphere of physical planning the Convention requires ( that planning must be carried out so as specifically to promote the conservation of the Wetlands included in the list and generally to promote as far as possible the wise use of wetlands.

b. Convention on Biological Diversity

The Convention was opened for signature on 5 June 1992 at the United Nations Conference on Environment and Development (the Rio “Earth Summit”).The Convention on Biological Diversity was inspired by the world community’s growing commitment to sustainable development. It represents a dramatic step forward in the conservation of biological diversity, the sustainable use of its components, and the fair and equitable sharing of benefits arising from the use of genetic resources.

The World Summit on Sustainable Development held in Johannesburg 2002 recommended partnership between governments, private sectors and the public at large to enhance management of wetlands. It also focused on sustainable development – that the existing generation meets the needs of the present generation without compromising the ability of the future generation to meet their own needs.

As a signatory country to the numerous international treaties and convention, it is therefore important to implement recommendations from global initiatives on environmental sustainable development, such as United Nations Summit held in 2000,wherein nearly all world leaders endorsed a set of eight time bound and measurable goals, named “the Millennium Development Goals” so as to combat environmental degradation, among other global problems.

Government regulations guiding Wetlands management in Kenya

a. National Wetlands Policy

For a long time, wetlands conservation in Kenya has been cross-sectoral in nature with no specific institutions charged with the management A number of government agencies, NGOs and community based organizations have in various capacities implemented wetlands conservation, management and utilization in a manner that has not always been consistent with previous or existing efforts due to the absence of a coordinated National Wetland Policy. The process for developing a wetlands management policy was initiated, but lack of focus and overlapping jurisdiction made it impossible to conclude and gain consensus on the matter. The Kenya Wildlife Service presently manages wetlands protected under the RAMSAR Convention. The Policy spells out clearly eight objectives to achieve its aim. The draft Policy seeks to:

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 Establish an effective and efficient institutional and legal framework for integrated management and wise use of wetlands which will provide an enabling environment for the participation of all stakeholders.

 Enhance and maintain functions and values derived from wetlands, protect biological diversity and improve essential processes and life support systems of wetlands.

 Promote communication, education and public awareness among stakeholders to enhance their participation in wetland conservation.

 Carry out demand driven research and monitoring on wetlands to improve scientific information and knowledge base.

 Enhance capacity building within relevant institutions and for personnel involved in conservation and management of wetlands.

 Establish a national wetlands information management system and database including tools and packages to targeted groups.

 Promote innovative planning and integrated management approaches towards wetlands conservation and management in Kenya.

 Promote partnership and co-operation at regional and international levels for the management of trans-boundary wetlands and migratory species.

b. Sessional paper No.6 of 1999

This sessional paper elucidates on the connection between environment and development, highlighting the key environmental challenges. It provides priorities for action, implementation strategies, and capacity building. It states that the overall goal is to integrate environmental concerns into the national planning and management processes and provides guidance for environmentally, socially and economically sustainable development.

c. The National Environmental Policy 2013

This policy proposes a broad range of measures and actions responding to key environmental issues and challenges. It seeks to provide the framework for an integrated approach to planning and sustainable management of natural resources in the country. It recognizes the various vulnerable ecosystems and proposes various policy measures not only to mainstream sound environmental management practices in all sectors of society throughout the country but also recommends strong institutional and governance measures to support the achievement of the desired objectives and goal.

d. The Environmental Impact Assessment and Audit Regulations, 2003

These are entrenched under section 147 of the EMCA. The regulations provide the framework for carrying out EIAs and EAs in Kenya before conducting any project. This helps in identifying the impacts of a project and deriving the mitigation measures to these impacts.

NEMA should oversee the implementation of this policy. Any project, before its commencement should undergo through screening to identify its impacts to both the social and environmental surroundings. It should therefore give permits to those projects and developments whose benefits exceed their cost.

e. Physical planning act, 1996 (Cap. 286)

This was an Act of Parliament to provide for the preparation and implementation of physical development plans and for connected purpose.

If in connection with a development application, a local authority is of the opinion that proposals for industrial location, dumping sites, sewerage treatment, quarries or any other development activity will have injurious impact on the environment, the applicant shall be required to submit together with the application an environmental impact assessment report.

f. Building Code: The Local Government (Adoptive By-laws) (building) Order 1968

It was established and enacted by the local authorities. They defined the building specifications and the quality of building material to be used. Connection to common facilities such as sewers, electricity and water pipelines was also defined.

g. Environment management and Coordination Act ( EMCA, 1999)

This is the superior environmental law in Kenya. The main objective of this act is the establishment of an appropriate legal and institutional framework for the management of the environment in Kenya. The Act further aims to improve the legal and administrative coordination of the diverse sectoral initiatives in the field of environment so as to enhance the national capacity for its effective management. The ultimate objective is to provide a framework for integrating environmental considerations into the country’s overall economic and social development.

In terms of environmental management, the EMCA 1999, provides a comprehensive and an appropriately harmonized legal an institutional framework for the handling of all environmental issues in Kenya.

Part VI (Section 68) of the Act makes it mandatory for an Environmental Impact Assessment (EIA) to be conducted for proposed projects.

Relevant institutions

a. The National Environment Management Authority (NEMA)

This is the government authority charged with the general supervision and coordination of the environment matters in Kenya. NEMA is the principal instrument of the government charged with the implementation of all policies relating to the environment. It came up because of EMCA that came to effect on the 14th of January 2000.

The functions of NEMA with regards to wetland management is to promote the integration of environmental considerations into development policies, plans, programmes and projects, with a view to ensuring the proper management and rational utilization of environmental resources, on sustainable yield basis, for the improvement of the quality of human life in Kenya, to take stock of the natural resources in Kenya and their utilization and conservation and to examine land use patterns to determine their impact on the quality and quantity of natural resources.

It is therefore the government’s watchdog in ensuring the management and conservation of environmental resources like wetlands.

b. Nairobi County Council

The main objective of the Council is to facilitate coordinated development and improve service delivery that would stimulate economic activity. and high quality of life to its residents who reside in its area of jurisdiction. It is responsible for ensuring a clean and healthy environment.

c. Water Resource Management Authority

The Water Resource Management Authority (WRMA) is a state corporation under the Ministry of Water and Irrigation established under the Water Act 2002 and charged with being the lead agency in water resources management. In order for WRMA to undertake its stipulated responsibilities, the Act provides for decentralized and stakeholder involvement. This will be implemented through regional offices of the Authority based on drainage basins (catchment areas) assisted by Catchment Area Advisory Committees (CAACs). At the grassroots level, stakeholder engagement will be through Water Resource User Associations (WRUAs). Among its objective is to manage and protect water catchments.

Measures for protection and management of wetlands

An important component of wetland protection and management is to identify what wetland functions need to be protected, and which wetlands need additional protection because they have other important characteristics. Wetland functions can be grouped into three broad categories: water quality improvement, hydrologic functions, and habitat functions. In addition to identifying what functions need to be protected, managing wetlands requires an understanding of how the functions are performed.

The two most common methods for protecting wetland functions have been the use of buffers and compensatory mitigation. Buffers are used to maintain existing functions by reducing the impacts of adjacent land uses. When impacts to wetlands are unavoidable, replacement of lost functions has typically been through compensatory mitigation in which other wetlands are created, restored, or enhanced using specific ratios based on area. Review of recent scientific information has shown that protecting the functions of wetlands by using only buffers and establishing “mitigation ratios” adequate since it considers providing protection in the immediate vicinity of a wetland and not disturbances that may occur elsewhere in the landscape.

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Theoretical framework

Wetlands are regarded as productive and dynamic systems that support life through their services and important roles which they play ( Finlayson et al. 1999). Their management is characterized by lack of clear policy formulation and implementation and in many cases conflicting roles in wetlands management. Importantly, knowledge of the location, distribution and character of wetlands, their values and uses, institutional and legal framework and challenges which is essential for effective management , is still required (Finlayson et al 1999).

Development and population growth are claiming increasing shares of land for housing, industry and infrastructure. The major cause of land loss, however, is degradation. Population growth has caused excessive exploitation of resources. Though development should be conducted to satisfy the desire of growing population, the conservation of the environment must not be stopped.

Ecosystems of all kinds are under pressure worldwide. Coastal and lowland areas, wetlands, native grasslands, and many types of forests and woodland have been particularly affected or destroyed. While forests decreased by about 5 per cent between 1980 and 1995, the rate of deforestation has been declining slightly. Urbanization will be one of the most important demographic trends of the twenty-first century. Indeed, virtually all the population growth expected during 2000-2030 will be concentrated in the urban areas of the world.

Population growth influences the spatial concentration of people, industry, commerce, vehicles, energy consumption, water use, waste generation and other environmental stresses. Relatively rapid and uneven population growth and economic development are occurring simultaneously with degradation of aspects of the earth‟s physical environment.  Development works must satisfy the needs of the present generation without harming the requirement of the future generation.

Throughout the world many fragile, biologically unique ecosystems, and the many species of plants and animals they contain, are threatened.  The challenge is to identify the complex interactions and effects of population, environment and development. To date, while some progress has been made, this challenge remains formidable for researchers and policy makers alike. Sorting out the interactions among population, environment and economic development needs more and better data.

Population growth, structure and distribution are important aspects of environmental stress in so far as everyone requires the basic necessities of water, food, clothing, shelter and energy, which directly or indirectly affect the ecosystems (World Resources Institute, United Nations Environment Programme, United Nations Development Programme and World Bank, 2005). Human encroachment of natural areas stems from the demand for both residential space and agricultural production.

Conceptual framework

My conceptual framework is based on the fact that there is need for emphasis on strong institutional and legal framework in order to achieve sustainable urban wetland management and also involve and create public awareness on the values and roles played by wetlands and the need to protect and conserve them. Monitoring and evaluation should be conducted to assess efficiency of these laws and therefore, in so doing, the wetlands will be able to provide their ecosystem services sustainably to meet human needs in both the present and future generations.

Recommendations on how to protect wetlands

  1. Wetlands are fragile ecosystems, which provide multiple ecological and socio-economical products, services and functions. They need an integrated approach to their planning and sustainable use. The Ministry of Environment, Water and Natural Resources in conjunction with NEMA and the County Government can formulate Policies and technical tools that are needed to counteract lack of appropriate information and intervention failure that cause wetlands to be used in an unsustainable way.
  2. Community outreach and education program among the various stakeholders in order to enhance increased awareness and knowledge on the importance of wetlands and the impacts of residential developments on them. Education and public awareness is essential to create commitment and positive attitudes towards conservation and sustainable utilization of wetland resources. NEMA and the various CBOs and NGOs can sensitize local communities on wetland management since they are closer and can associate well with the local people.
  3. The Ministry of Environment should work together with the Ministry of Lands and the County Government to provide a secure land tenancy system whereby the riparian areas should be clearly mapped and those living near this area should have legal title deeds. This will enhance conservation of the wetland. Regulation, protection, management and conservation of wetlands within public, private and community land is of essence.
  4. The County Government should advocate for zoning measures to be put in place for wetland reserve and strict protection measures to be enacted for both the wetland and rivers.
  5. The Central Government should recognize existing urban wetlands and that the designation of Wetlands Importance provides just the starting point for securing the sustainability of wetlands and the maintenance of ecosystem services, and that development and implementation of a management planning process, involving all stakeholders, is necessary to achieve this.
  6. While wetlands play a role in reducing pollutant levels of inflowing water, they also require protection as water resources. The wetland receives untreated runoff from much of the developed urban area. The City Council should advocate for use of water quality standards that will go a long way in protecting the wetland from such inputs and also manage both solid and liquid waste.
  7. The Ministry of Environment, Water and natural resources and NEMA should work with other concern organisations to monitor wetlands overtime since it is important to assess its functioning and maintaining wetland integrity. This can be done through mapping which is an effective tool for monitoring wetlands. Use of Remote sensing technology has shown to be an excellent source of data when mapping and monitoring smaller wetland habitats and vegetation communities.
  8. NEMA should ensure that any drainage, conversion, burning, alteration of a wetland, or introduction of alien and invasive species in a wetland will be subjected to approved standard procedures including Environmental Impact Assessment (EIA), Strategic Environmental Assessment (SEA), Cost Benefit Analysis (CBA), and adequate public participation.


DCM (2007). Wetlands: Their Functions and Values in Coastal North Carolina. Morehead City: DCM Printers.

Finlayson, C. et al (1999). Global Review of Wetland Resources and Priorities for Inventory: Summary Report in Global Review of Wetland Resources and Priorities for Inventory, (Eds. C. M. Finlayson and A.G. Spiers). Supervising Scientist Report No. 144, Canberra

GoK (2008). Sessional Paper No.6 of 2008 on Environment and Development, Ministry of Environmental Conservation. Nairobi: Government printers.

Judith, A. (2007). Watersheds: Values of Wetlands. Carolina: NCSU Group.

World Resources Institute (1995). Millennium Ecosystem Assessment. Ecosystems and human wellbeing: Wetland and Water synthesis. Washington: WRI

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