Urbanization: An analysis
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Published: Tue, 02 May 2017
2.1.1 Current discourse in urbanization concept
Urbanization is growing in most part of the world in line with technological discovery and human civilization. The rapid urbanization began at England’s industrial capitalism (Clark, 1998) at the end of 18th century and it spread rapidly after the use of coal for the industry primary raw material and a better transportation system (Hall, 1994). In developing world, urbanization started in 1950 after the Second World War (Crenshaw, 1991) and it is growing everywhere now especially in Africa and Asia. United Nation’s report indicated that by 2050, most population will be concentrated in cities and towns of developing countries. By this year, if Africa and Asia continue their current rapid growths, 50 percent of the population will live in urban areas and in 2010 it is predicted that the urban population is higher than the rural one (figure 2.1)
Figure 2.1 Urban and rural population of the world, 1950 – 2030
(Source: Junaidi, 2006)
There are four existing definitions for urbanization concept that mostly be the attention of urban planners. First, urbanization is seen as a process in which there have occurred transferring ideas and practices from urban areas into surrounding hinterlands. Second, urbanization is viewed as the increase both in behavior and problems considered to be urban types of rural area. The third, urbanization is related with the process of population concentration in which it is found the increasing ratio of the urban population to the total population (Phren. K. P, 1962) and the fourth, urbanization is seen as the combination of densification or the increase of density of people and building unit and the outward spread of people and built areas (Forman, T. www.cambridge.org). However, all of these definitions are interelated that all the urban planner needs to consider them in urban planning process integratedly.
There are many related concepts involved from these in defining urbanization definition. From economic point of view, urbanization tend to connect it with labor division; demography related with density and population size, sociologic regarding to the way of living, and the last is geography from characteristics of the built up environment (Crenshaw, 1991). However, most analysts agree that demography is the basic criterion in differentiate urban and rural area (Clark, 1998, White, 1994, UNECA, 1968) because the population growth, including population density change, are the most quantified way to see the growth of an area. The most common example is United Nation that also uses the population size to standardize the urban localities and city among the nations.
Mostly literatures argue that the driving force for urbanization is economic reason (Clark, 1998; Crenshaw, 1991, Jeremias, 1988), but there is a difference in the background of which. In developed world, rapid urbanization occurred because of industrial revolution, capitalism, and the invention of technology and a better transportation system while in developing countries, urbanization tend to occur because of economic imperial. The developing countries’ cities were previously prepared for supporting the economic interest of the powerful regime to earn money, to expand and control foreign trade, to create new markets for products and to acquire raw materials and cheap labor (Crenshaw, 1991).
Many specific reasons for the driving force of urbanization and the traditional literature categorized them as push and pull factors. The push factor occurred because of the pressure of poverty problem and environment degradation in rural area. The poverty occurs because of limited job opportunities, limited land for agriculture and other natural resources limitation. The pull factor is related to the attraction of urban area for a better life. It is often related to a wider job opportunity, higher economic growth, better services and modern facilities (Baiquni, 2004). From this pull and push factors, it could be seen the disparities between urban and rural area are the main reason making more and more population concentrated in urban area.
2.1.2 Urbanization determinant
The proximate determinants of urban growth can be grouped into three categories: firstly, the total population; secondly, rapid economic growth; and the third, percentage of built up area and areal extend (White, 1994).
The more population size of an area, the more urbanized it will be and it is positively related to the growth of urbanization (Rogers, 1982). The increasing of population size is caused by both migration and mortality. Migration flows occur because of employment availability in nearby cities and towns, ethnic connections in particular cities, the roads development and the accessibility of transportation (Connell et al, 1976). Some researches stated that the economic imbalance resulting wage disparities in urban and rural is a major reason for high levels of rural-to-urban migration. The size of population in urban area will be in line with the needs of water for these urban dwellers.
It appears that rapid economic growth related to urbanization (Becker & Morrison 1988, Preston, 1979) that the urbanization level of an area can be marks by its rapid economic growth. Mostly in urban area people do not work in agriculture sector as in rural area, but in service and manufacture. The manufacture developments in urban area have triggered the employment opportunities for rural people to come, and a higher wage offered by manufacture sectors compared to the agriculture ones results in a better economic condition and quality of life. The quality of life will also influence to the water consumption quantity and quality.
Percentage of built up area
The urban characteristic can be seen from the density of people and the increase of building units. The sign is can be seen from the reduction of green spaces or the changing from low to high-rise apartment buildings. Other sign of urbanization is the city grows by expanding outward. Cities may also urbanize by rolling over suburbs, and suburbs urbanize by rolling over farmland or natural land (Crenshaw, 1991). The changing of landsape by built up environment will be related with the number of recharge area and wastewater quantity that will influence the groundwater.
2.2. Groundwater system on earth
Groundwater constitutes about 98 percent of water on earth and both its storage and flow is one of the key elements of natural water systems (Foster, S, 1998). This fact makes groundwater an essential element to human life and economic activities. The details about groundwater hydrology are beyond the scope of this discussion, but a general overview will be presented.
Figure 2.2. Hydrology Cycle
Groundwater is water located beneath the ground surface in soil pore spaces and including one component of the earth’s water cycle. The water cycle is called the hydrologic cycle and it involves the movement of water as rain, snow, water vapor, surface water and groundwater. The earth’s water is constantly circulating from the earth’s surface up into the atmosphere and back down again as precipitation.
When rain falls, a part of it infiltrates the soil. A proportion of this water will be taken up by plants while some will infiltrate more deeply, accumulate above an impermeable bed, saturate the pore space of the ground, and finally form an underground reservoir. This underground reservoir is called an aquifer, a place from which significant quantities of water can be abstracted for human needs. An aquifer’s productivity to store and transmit water are not the same, it depends on the fundamental characteristic of its constitute. Some of which are granular sediment such as sand, cement sediment such as sandstone and limestone, rock and fracture rock. The ground above an aquifer through is called the vadose zone; it is where the excess rainfall passed vertically. The level to which the ground is fully saturated is known as the water table. The nature, the occurrence of groundwater and the movement of water trough groundwater system is shown in the figure 2.2.
2.3 Urbanization and groundwater resources
2.3.1 Current Discourse
Urbanization has been recognized as a trigger of social and environmental problems (Dogan & Kasarda 1988, Timberlake 1985). The rapid expansion in groundwater exploitation of many industrialized nations occurred during 1950–1975 while in in most parts of the developing world it occurred during 1970–1990 (Zektser & Margat 2003). The groundwater is estimated to provide at least globally 50% of current potable water supplies; 40% of the demand from industries, and 20% for water use in irrigated agriculture (Foster, 1998). These proportions vary widely from country to country and within countries depending on human activities on it.
The groundwater is generally the main water resource to be tapped for urban dweller needs if a city has productive aquifers (Minciardi, 2007; Somma. 1997; Hiscock, 2002). This is because the groundwater has an excellent natural quality with significant savings in treatment costs compared to other surface water source. Other reason is because groundwater is a more secure source of water supply during long dry periods compared to the surface water resources (Clark, 1998, Ohgaki, 2007). Groundwater is also a suitable for public supply and independent private use, especially during the early stages of development (Foster, 1998).
Two common methods for urban aquifer exploitation are by hand-dug wells and drilled boreholes (Foster, 1998). Hand-dug wells are usually less than 20 meters depth with diameters of 1 meter or more. In this method, the water is usually abstracted manually or by small pumps. The water supply boreholes are mechanically drilled, usually having smaller diameter than hand-dug wells, but much deeper ranging from 20 to 200 meters or more in depth. These two methods if developed in uncontrolled manner will cause groundwater depletion as it has occurred in many urban cities over the world (Ohgaki, 2007; Minciardi, 2006; Foster.S.S.D, 2001).
2.3.2 Urbanization impact to groundwater resources
It has been identified that urbanization results in aquifer depletion, saline intrusion, and land subsidence, changing patterns and rates of aquifer recharge and affecting the quality and quantity of groundwater (Foster, 1998, White, 1994, Ohgaki, 2007, Minciardi, 2006). In this discussion the overall focus will be on the depletion of groundwater quantity related urbanization.
Figure 2.2. Urban development and its impact to water resources
Source: (Foster, 1998)
From the figure above, it could be seen the urban development and its impact on the changing of urban groundwater. In the beginning, all cities evolve from small settlements; formal or informal. In this stage, the city dwellers can abstract groundwater using shallow well and boreholes as the groundwater is still abundant. As the infrastructure for wastewater either has not been adequate yet or less than the population needs, the wastewater starts discharging to the ground and starts to pollute the groundwater supply.
When the town becomes city, the need of water supply is getting higher resulting from rapid urban population growth in contrast with the decline of groundwater supply. As the result, the well is deepened and there has been occurrence of land subsidence because of more urban dwellers do this deepening. The wastewater is still continuing to pollute the groundwater. The city then expands in line with the urbanization trend resulting to more water needed, more contaminant enters groundwater system and water table rises beneath the city. The urban dwellers start abandons their groundwater resources while the groundwater exploitation of hinterlands area as the alternate sources are getting higher.
Because of the storage capacities of most aquifers are large, there is often a major time lag before the problems of groundwater depletion, water table rise and groundwater pollution becomes fully apparent (Foster, 1998). Further, there is increasing water supply scarcity with higher marginal costs for urban water supply. At the end, the traditional use groundwater that is low cost, minimally treated, and abundant for public water supply in urban areas is being threatened.
The abstraction of groundwater has proved to be the cause of a qualitative decline in water levels. If abstraction is limited, the water level will be stabile at a new equilibrium. However, if occurs either a heavy or and concentrated groundwater withdrawal until it exceeds the local recharge, the water level may continue to decline over many years. As the result, there will be spreading of depress water level, land subsidence, water quality deterioration, sea water intrusion, up-coning and induced leakage of polluted water from the surface (Foster, 1998; Wangsaatmaja, 2006; Braadbaart, 1997)
Mostly the problems and causes of aquifer depletion and contamination are clear while immediate solutions are not. General solutions involve some combination of increased recharge rate, reduced consumption rate, efficiency gains, and reduced or eliminated contaminant sources (Vo, 2007, Venkatesh Dutta, Foster.S.S.D, 2001). For example, reducing the velocity of runoff and providing time for recharge could enhance groundwater supplies significantly and at the same time reduce land-based sources of pollution to receiving waters.
Land subsidence occurs for a variety reasons, but natural and manmade groundwater abstraction is one of the most contributor to this condition. The remedying efforts of the land subsidence impact involve a high economic cost (Foster, 1998). It is because differential subsidence damages roads, buildings, and other surface structures and it can seriously disrupt underground services such as water mains and water pipelines, sewers, cable conduits, tunnels, and subsurface tanks. In cities located on flat topography, subsidence can disrupt the drainage pattern of rivers and canals and can increase the risk of flooding. The land subsidence effects can be more serious in coastal areas because it can increase the risk of inundation (Hiscock, 2002).
The uncontrolled aquifer exploitation will impact on saline intrusion and it is usually occurs in coastal area. When the groundwater levels fall, the water flow direction change occurs. For thin and alluvial aquifers, this condition results in the formation of wedge shaped pattern and but in the thicker ones, salinity inversions often occur with intrusion of sea water in near-surface aquifer and fresh groundwater in deeper area. Once salinity has diffused into the pore water, its elution will take decades or centuries.
Uncontrolled exploitation has consequences to contaminate the deeper aquifer. This induced pollution is caused by inadequate well construction, vertical pumping-induced, and sewage. Some rapidly developing cities have provided mains sewerage and generate large volumes of wastewater but this wastewater is normally discharged untreated or with minimal treatment to surface watercourses. It especially occurs in more arid climates (Anderson, 1987).
2.4 Urbanization Impact on groundwater management policy
Although groundwater is the source of drinking water for most people, it is often ignored and taken for granted in urban planning program. The problem was expressed this way by the US Water Council in 1980:
“The role of groundwater in water supply often has been slightenend in the past, one reason being believed that groundwater couldnot be adeqately evaluated in terms of avalibility, chemical quality, economics, or injuctive supply with surface water resources. However, substantial progress in groundwater analitical capability in recent years has made the resources more amanable to rational planning and management operation” (US Water Council in Grigg, 1996)
Urban groundwater problems evolve over many years or decades as the result of slow the respond to most groundwater problem. The groundwater depletion and pollution problem are usually solved in incremental way by abandoning the shallow wells and replacing them with deeper boreholes to the aquifer (Grigg, 1996). However, this approach may only provide a temporary solution and if the urban planners continue this method, the groundwater supply will be in more stress condition. Therefore, the more comprehensive and sustainable groundwater planning and management approaches are needed to be developed (Tellman).
2.4.1 Groundwater Management
Many literatures define groundwater management differently. Some emphasizes on the technical aspect such as engineering and hydrology, some are the process of managing and some others are the combination of them. However, the common similarity is on their objective that groundwater management is prepared to ensure that groundwater resources are managed in a fair, equitable and sustainable manner (Hiscock, 2002; Ohgaki, 2007; Minciardi, 2006;Venkatesh Dutta).
Groundwater management can be defined as a number of integrated actions related to both natural and managed of groundwater pumping and recharge to achieve the long-term sustainability. California government in 2003 DWR Bulletin 118 2003 defines groundwater management as a set of activities including the planned and coordinated monitoring, operation, and administration of a groundwater basin or portion of a groundwater basin with the goal for long term sustainability of the resource. As the result, the groundwater management involves a number of engineering disciplines including survey and monitoring, geological interpretation, hydrological assessments, hydrogeological modeling, chemical and geochemical assessments and optimization.
Groundwater management also deals with a complex interaction between human society needs and physical environment and it presents a difficult problem of policy design (Foster.S.S.D, 2001; Somma, 1997). For example, aquifers are exploited by human decisions for sustaining their lives and overexploitation cannot always be defined in technical terms, but as a failure to design and implement adequate institutional arrangements to manage people who exploit the groundwater resource. Common pool resources have been typically utilized in an open-access framework because of the characteristics of groundwater resources (Somma, 1997). When no one owns the resources, the users do not have any obligation to conserve for the future, and as the result, self-interest of individual users leads them to overexploitation.
Groundwater management is a debated issue with very few examples of effective action on groundwater resources. However there some approaches that several studies concluded them as a successful groundwater methods, for example, sustainable groundwater development and management in the overexploited regions is treated by combining artificial recharge to groundwater and rainwater harvesting; management of salinity ingress in coastal aquifers; conjunctive use of surface water and groundwater; water conservation by increasing water-use efficiency; regulation of groundwater development.. Further, there also innovative methods of recharging the groundwater and storing water in floodplain aquifers along the river banks to enhance the ultimate irrigation potential from groundwater.
The following four steps are essential for most groundwater management cases. Firstly, there must be regular and accurate assessment of actual groundwater use in both rural and urban areas to correlate with recharge and extraction. Secondly, expansion should be strictly monitored. Thirdly, separation of feeders for domestic and agricultural power and the fourth, ways must be explored to empower and entrust the communities to manage the groundwater uses.
Development of groundwater management is usually begun by an assessment of groundwater problems and management issues, a compilation of groundwater management tools, an identification of action to address issues and problems, selection of the management plan and a discussion of implementation aspects of the plan. Mostly, the suitable groundwater management approaches are identified at the local water agency level and directly resolved at the local level. However, the State also has role in providing technical and financial assistance to local agencies for their groundwater management efforts. The Department publishes a regulatory framework for groundwater management to ensure that the groundwater resources are maintained and used in an orderly, equitable, and sustainable manner. If groundwater management is obeyed and the problem cannot be directly resolved at the local agency level, there is usually an additional actions such as enactment by local governments or decisions by the courts.
2.4.2 Sustainable groundwater management
Groundwater is an important source of clean drinking water in many areas because of its characteristics, but mostly a sustainable management has not yet been established for this resource. Natural water bodies have become the place for storing human activities products, such as wastewater and other industrial pollution, causing little natural water storage capacity left.
The sustainable groundwater management needs to involve a larger management system including the development of alternative surface water supplies, reallocation among economic uses of water, and regulatory limits on abstraction. Like other water resources management and other environment issues, all elements of active aquifer management must involve stakeholder participation and whole basin analysis. It means that sustainable groundwater management should take place on various levels, starting from the localized borehole owner and user to the regional aquifer, basin and catchment area. At the end, the groundwater development will much depend on management principles applied by Local authorities, Government and Inter Governmental development planning and management strategies.
By taking appropriate measure, sustainable groundwater management development can be built. In urban planning practice these measures tend to reduce sewer overflows, improve the quality of treatment plant effluent and prevent falling water tables in areas around towns, cities, and the hinterlands.
2.4.3 Major approaches in sustainable groundwater management
The literature generally literatures found that the approaches for sustainable groundwater management are divided into spatial and a-spatial approaches as below. The most common similarity in these approaches is that one method cannot stand alone but must be integrated and connected with other disciplines and other sectors.
Integrating sustainable groundwater in spatial planning and management
a.1) The use of `Hydrological Design Principles’
This approach involves zoning related to the catchment planning approach, the location approach, and buffering approach. The `Hydrological Design Principles’ as a basis for making spatial planning decisions or design of land use patterns is the most common approaches for groundwater management.
The Catchment Planning Approach objectives are both to adjust land uses or activities with environmental requirements in the catchment area or drainage basin and to prevent peak discharges. This is implemented by allocating land use profiles to each catchment area and by taking account to maintain or increase the catchment areas’ water storage capacity. The attention to be paid is to both water quality and quantity aspects, which are to be managed with the most important goal for achieving an ecological balance with the land use activities.
The Location Approach’s aims are to order the various land uses and activities within each catchment area so that the affect occurs is as little as possible to each of them. In this approach, the land uses that have greater demands on water quality are located upstream of more polluting ones, while the more vulnerable uses is located in areas of groundwater seepages. The clean land use activities are placed in the infiltration areas.
The Buffering Approach is used to give chance the land uses with incompatible environmental requirements to co-exist. A well-known example at the local level is the hydrological buffering of natural sites from surrounding agricultural land. This can be achieved through appropriate design and management measures that can be implement in a relatively easy and quick manner.
a.2) Integrating land use activities, groundwater systems and the environment
The approaches are by water storage, habitat creation and natural water treatment combined with new urban development. In many places where the abstraction of drinking water causes damage to nature, water may be abstracted elsewhere instead, for example is in the hinterlands of that area. In some cases, groundwater abstraction should be stopped regarding to riverbank filtration. Water from the river can be pumped into the ground under the banks and later abstracted when it has been sufficiently filtered by passing through the sand and clay in the sub-soil.
Raising storage capacity in the river basin through habitat creation, landscaping and establishing outdoor recreation areas are also other approaches for this method. The groundwater system had double function for human life.
a.3) Ensuring enough room for water: ‘Catch water where it falls’
It is mostly done in the areas around the main rivers or flood prone area. It can be in line with habitat protection because the raising the water storage capacity by lowering the ground level of the river or moving back the dikes back offer opportunities for nature development. The widening ditches and raising the drainage level can increase the water storage capacity. As the result, more room for water and the rainwater can be infiltrated into the soil instead of being drained away as quickly as possible to the sewer. An advantageous effect of giving water more room is the greater opportunity it presents to make use of natural filtration and water purification processes.
a.4) Controlling subsurface contaminants load and ensuring sufficient clean water
Water pollution problems can be partially minimized or controlled by delineating source protection zones around major groundwater catchment areas. On the other hand, there are some related approaches such as firstly; appropriate planning provisions or mitigation measures to reduce contaminants load in particular areas, especially where aquifer is highly vulnerable. Secondly, to moderate the subsurface contamination to acceptable levels by considering the vulnerability of local aquifers to pollution, land use planning to reduce potential pollution sources. Thirdly by selecting controls over effluent discharges and other existing pollution sources and the fourth is by planning waste water treatment or landfill disposal sites regarding to groundwater interests and impacts.
Integrating sustainable groundwater in a-spatial planning and management
b.1) Institutional management
To improve groundwater management, a strong institutional framework is prerequisite. Regarding to groundwater characteristics, an ideal institutional framework should to include legislation to provide clear definition of water use rights that is separate from land ownership. It could be implemented through granting of licenses and tax for groundwater exploitation in a specified manner. Other approach is by regulating and supervising the discharge of liquid effluents to the ground, the land disposal of solid-wastes, and other potentially polluting activities with a need legal consent or planning approval. Some literatures also presented about the behavior change and prospectus in groundwater that is believed can be last longer than the technical approaches.
b.2) Demand side management
Groundwater management not only requires adequate assessment of available resources and hydrogeology by understanding of interconnection between surface and groundwater system, but also actions required for proper resource allocation and prevention of the adverse effects of uncontrolled development of ground water resources for short and long term.
One of the important strategies for this is a-spatial sustainable management of groundwater by regulating the groundwater development in critical areas using demand side approach. Management of demand means managing efficiency of water use, interaction among economic activities that is adjusted with water availability.
In demand side management, socio economic dimension plays an important role that it also involves the managing the users of water and land. It is because the regulatory interventions in demand side management such as water rights and permits and economic tools of water pricing will not be successful if the different user groups are not fully involved. As the result, for achieving effective management of groundwater resources, there is a need to create awareness among the different water user groups and workout area specific plans for sustainable development.
From among these two characteristics, it can be concluded that there are two emerging broad types of management approaches for groundwater. Firstly, approaches including tools such as power pricing, subsidies for efficient technologies, economic policies discouraging water intensive crops, etc. Secondly, approaches dealing with specific aquifers on the basis of command and control management through a resource regulator. Whichever approach is adopted, the development and management of these resources must be based on an adequate knowledge of a clear comprehensive situation of groundwater aquifer system and its replenishment.
CHAPTER II 1
URBANIZATION AND GROUNDWATER PLANNING 1
2.1 Urbanization 1
2.1.1 Current discourse in urbanization concept 1
2.1.2 Urbanization determinant 3
a) Population size 3
b) Economic growth 3
c) Percentage of built up area 4
2.2. Groundwater system on earth 4
2.3 Urbanization and groundwater resources 5
2.3.1 Current Discourse 5
2.3.2 Urbanization impact to groundwater resources 6
a) Groundwater depletion 8
b) Land subsidence 9
c) Saline intrusion 9
d) Induced pollution 9
2.4 Urbanization Impact on groundwater management policy 9
2.4.1 Groundwater Management 10
2.4.2 Sustainable groundwater management 12
2.4.3 Major approaches in sustainable groundwater management 12
a) Integrating sustainable groundwater in spatial planning and management 13
a.1) The use of `Hydrological Design Principles’ 13
a.2) Integrating land use activities, groundwater systems and the environment 13
a.3) Ensuring enough room for water: ‘Catch water where it falls’ 14
a.4) Controlling subsurface contaminants load and ensuring sufficient clean water 14
b) Integrating sustainable groundwater in a-spatial planning and management 15
b.1) Institutional management 15
b.2) Demand side management 15
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