Lecture 2: Impact of urbanization on environment

追加: 2026-05-06

[00:00:15]Dear learners, I am Dr. Vishal Prasad, assistant professor from the Institute of Environment and Sustainable Development, Banaras Hindu University.

[00:00:23]Here to interact with you on the SAM platform regarding the course environmental issues, challenges and management. Dear learners, welcome to the course on environmental issues, challenges and management. This is week one module number one human environment and urbanization and lecture number two impact of urbanization on environment.

[00:00:43]This is going to be the table of content for our today's learning. What is urbanization? Process of urbanization, impacts of urbanization on environment which includes habitat and biodiversity decline, pollution of air, water and soil, disruption of water cycle, urban heat, island effects and resource and energy consumption. So to start with what is urbanization? Urbanization is the process of populations shifting from rural to migration which is the migration of rural to urban areas leading to the growth of cities and corresponding increase in the population or the proportion of people living in cities. Increase in the portion of people living in the cities versus the rural areas. This phenomena involves a population shift, a decrease in rural populations and the societal and environmental adaptations that follow.

[00:01:40]First of the thing is population movement which means people are moving from the countryside to the towns and cities to find work and a better lifestyle. Second is societal changes.

[00:01:52]This shift from rural to urban leads to changes in how people live, work and interact creating a new urban way of life known as urbanism. The people the society how they interact makes develop the urbanism system of life living in an urban setting. The another one is or the most important for us is the environmental impacts. Urbanization can cause environmental issues like habitat loss, increased pollution and higher regional temperatures. This is all we are going to discuss in the coming slides. Now, and another is infrastructure development. Urbanization supports the growth of cities and this the growth of such cities requires new infrastructure, services and resource to support a larger population. This slide shows you the process of urbanization where you can see earlier we are living in a rural area and from rural rural area there is a continuous shift towards the urban setup. Initial settlement is the rural area then there is infrastructural development in terms of development of basic roads, basic structures like hospitals, schools and other things. Then that particular becomes a suburban area and from there industrial and commercial expansions occur in the urban areas where people start migrating from this rural area and then residential growth starts occurring. This residential growth turns into a very big increased city and this particular level of urbanization in a country or region occurs. So the level of urbanization in a country or region is often measured by the percentage how many people or the percentage of population is living in the urban area. That percentage describes how urbanized a particular country is. What is the impacts on envi environment? There are various other things related to urbanization. We will focus here on the impacts on the environment. So if you can see as urbanization occurs what happens there is increased pollution there are is a there is an increase in urban heat islands habitat loss or habitat destruction is there altered hydraological cycle or the water cycles are there. So in totality what happens the concentration of people industries and vehicles in urban centers intensifies in environmental pressures which are far far beyond the city limits. The pressure on the resources natural systems which we are putting in an urban setup is more than that particular urban setup can handle. So urbanization severely impacts the environment through increased pollution, altered hydraological cycles, habitat destruction and the creation of urban heat islands. We will discuss each in details further. So first is the habitat habitat loss and biodiversity decline.

[00:04:54]So the physical expansion of cities known as urban sprawl is a primary cause of habitat loss. As we saw in our earlier site, we were earlier having rural setups. This is the rural setup in which you can see a lot of biodiversity is there in terms of species richness. Plants are there, variety of animals are there. In plants also variety of plants are tall trees, grasses, shrubs, everything you can see are there in where Then so this is what is known as the biod diversity or the species richness. But when this shift occurs to a urban setup where lot of buildings infrastructure all such things are coming up then what happens the habitat of such small animals or plants are lost. When the habitat will be lost where are they going to survive and how are they going to survive? So this is a serious matter of concern. So in habitat loss the first of the most important thing is destruction of the ecosystem. So if we see an example of an e agricultural ecosystem over here we can see several animals several plants several birds butterflies everything is dependent on this in an ecosystem and they're interrelated. One is dependent on the other. So what means that if one component of the ecosystem is vanishing the dependent component on that particular component will also get vanished away and this happens in during the process of urbanization.

[00:06:31]Urbanization leads to the conversion of natural landscapes such as forests, wetlands and agricultural land into imperous services like roads and buildings. There is no percolation left.

[00:06:44]Second is habitat fragmentation due to urbanization. What you can see here that development breaks up remaining natural areas into smaller isolated patches. Now you can see one patch is here, one patch is here, one patch is here and urban setup is here. Meanwhile here also plannings are going on where buildings and other things can be taken up. So this such kind of a small patches development disrupts ecological connectivity between uh the patches preventing the movement of animals and plants leading to decreased genetic diversity. So for having a greater genetic diversity there should be an interaction between various species living in a particular ecosystem or a community. But when that community is fractured due to development and the communities are separated into small patches then the individuals residing in one patch particular patch will not be able to interact with the community residing in any other patch and if such kind of a thing happens then genetic recombination chances are very much minimized. Another is reduction of species. This is very much alarming and this thing needs to be answered or this thing needs to be debated upon. What happens here? The process of urbanization results in a progressive extinction of species sensitive to urban conditions. All species cannot survive especially the animals the plants mostly the animals are very much affected. They cannot survive in the urban setup. They are free living animals and they they do not have the capability to live under binding conditions under strict closed doors or the fancies conditions in which humans are living. So while while such things of wild species are getting extinct what happens it the urban setup favors some kind of urban dwellers like rodents, rats, pigeons and certain plants and when such things happens these are rodents and other things might become carrier of certain diseases. So you can see here the urban ele sorry Asian elephants Indian leopard great Indian bustard genetic dolphins sumatran orangutan Florida panther all these species are getting extinct getting lost from our ecosystem from our biodiversity uh gene pool. So this is all because of the urban sprawl. Their natural places of living of such organisms is being encroached by the urban setups or urban buildings.

[00:09:36]This is a problem and this problem needs to be answered.

[00:09:41]Second apart from the habitat loss is pollution. Pollution of everything air, water and soil. These are the basic systems on which even humans develop.

[00:09:51]And so we are developing urban setups on the cost of human health itself. So you can see that urban areas are the major sources of various pollutants which degrade the quality of air, water and soil creating significant health and ecological problems. Here you can see the slide is showing you uh a case of air pollution. Air pollution the high concentration of vehicles industrial activities and energy consumption in cities releases large amounts of very large amounts of pollutants including PM2.5 nitrogen oxide and this creates a lot of smog. You will see f foggy weather all around you at most of the time in the cities which is responsible for the respiratory illness and other health issues which most of us are face facing today we are having problem in breathing we are sneezing coughing every time and all this. So you can see the primary causes are we are having a lot of transportation means in terms of vehicle emissions and vehicle emissions is very high is always on the constantly rise industrial emissions are throughout the day 24/7 these industries are working and they are releasing lot of fumes in the open environment. Then power plants are generating a lot of toxicants a lot of pollutants which are either being dumped into the water or in the air. Air is is definitely being contaminated by these power plants. So where are these things all going into?

[00:11:20]These are all going into the air and what are they doing? They are getting mixed up with the air which we breathe in. So what ultimately happens? We are breathing such an air which is highly pollutant which is full of toxic toxicants and very much irritating. But in the urban setup we have to live we have to survive. This is what is happening. Next is water contamination.

[00:11:45]Water contamination the sources you can see here the are the industrial discharges or the urban runoff and what effects they are causing? They are polluting the water. They are harmful to the aquatic life. This is the water which we are using for our daily purposes. This is the water in which the aquatic life is thriving, surviving and uh providing essential resources to the human survival. But due to urbanization what is happening? All this wood quality water is getting polluted. So imperous urban surface prevent rain from soaking into the ground. The it is no more able to go inside the ground because the uh surface is now not porous. It has become non-porous due to concrete, due to asphalt and other things which we are using to construct our urban setups.

[00:12:40]In this particular imperous surface prevent rain from soaking into the ground increasing strong water runoff and this runoff carries pollutants like oil, chemicals and trash into nearby waterways contaminating drinking water sources and harming aquatic ecosystem.

[00:12:58]So all such of problems are occurring in the water bodies also. Next is waste generation. Now this waste generation is due to uh unhealthy lifestyle or wasteful lifestyle. Humans are generating a lot of waste on a continuous basis. We do not need things but we are taking it and in that process we are generating a lot of waste. So the sheer density of population and consumerism mostly the consumerism this is very unjudicial. Population is definitely increasing you cannot stop that. We have to have take into consideration various serious measures to control the population. But consumerism is one thing which people can take control of but unfortunately this is not happening. So consumerism in cities creates enormous volumes of waste. Improper disposal enormous volumes improper disposal and inadequate management systems can lead to contamination of land and water genetic toxic leeades.

[00:14:02]Now whatever leeches you are getting this is going inside the ground and greenhouse gas emissions. So you can see there are all things present in the urban setup vehicles residents sale setups municipality all these are generating a lot of waste and you can see this waste bin is full spillage is there every time you will see any dust been put in any corner of the city it will be full dumped completely within minutes it is emptied it is again fulfilled within minutes and it is spilling all the time so this is What is because of the urbanization?

[00:14:45]Because of the increasing pressure of the urban setup on the cities beyond their carrying capacity. Then third one impact of the urbanization is disruption of water cycle. So the built environment of cities fundamentally alters the natural water cycle leading to several negative consequences. These are reduced infiltration, increased runoff and flooding, lowered water table. In reduced infiltration, what happens that the paved surfaces, buildings and roads prevent rainwater from seeping into the ground to replenish the groundwater.

[00:15:22]It is not recharged.

[00:15:28]No recharge is there. Second is increased run. Whatever water is being poured in form of rainfall, it is getting washed off. It is not seeping inside the ground. If it is not seeping, it is getting going and getting washed off and creating a lot of floods and finally it is going into the sea mixed getting mixed with the salt water and it is no more useful for the human beings.

[00:15:51]So instead of natural absorption, rainwater quickly becomes surface runoff overwhelming drainage systems and increasing the frequency and intensity of floods. And another thing is lowering of the water table. Water table is getting lowered down, lowered down. What happens? Less groundwater recharge as we see in the upper point itself causes a drop in the water table. The water table is getting dropped down which can lead to wells running dry and salt water intrusion into the coastal areas. If the uh water falling from the or the rainfall is not going down, what will happen? the water from the coastal nearby coastal areas will enter into the groundwater and the groundwater will also become very much salty not fit for human consumption. This slide is shows you the disturbance of the in the water cycle due to urbanization. So you can see because of the construction or because of the paving there is a reduced infiltration and because of that reduced infiltration increased runoff and flooding occurs and because of that reduced infiltration lowering of water table is also occurring. Next is the urban heat island effect due to increased urbanization. So cities are often significantly warmer than surrounding rural areas due to urban heat island effect. So what happen? What are the causes? The causes are concrete, asphalt and other dark imperous which are imporous surfaces absorb and store imperous surface absorb and store more solar radiation. So if any object is storing more of the radiation, it will be heated up in the due course of time.

[00:17:29]The lack of vegetation also reduces the cooling effect. No vegetation, no cooling effect due to the evapo transpiration. What happens that evapo transpiration occurs, water goes from the ground to the clouds and from the clouds it's come back, the humidity is there and all those things. So that particular cycle is also disrupted while anthropogenic heat is generated from vehicles, industries and air conditions.

[00:17:56]Anthropogenic activities demand a a lot of energy and from that demand energy demand a lot of heat is being generated and that heat is getting accumulated in the uh cities and that creates a lot of heat island problem. So impact of this urban heat island is that higher urban temperature increases energy consumption. For cooling higher energy is required. If it is hot more and more air conditioning, more and more cooling will be required which will need a lot of energy. Degrade air quality by accelerating ozone production and pose serious health risk to residents particularly during heat waves. Problem of heat stroke is there. Continuous threat is there. So you can see what happens. The rural areas, the nearby areas, the temperature is very pleasant around 25 which is good enough for humans to survive. But in urban areas there is a continuous increase in the temperature due to continuous heat accumulation and the reasons being concrete and asphalt surfaces, reduced vegetation, increased energy consumption, elevated temperatures in the city center. So this is the problem which of urbanization that urban heat islands are continuously getting up get in uh developed and this is causing a lot of health related issues to the human beings. Fifth and foremost the resource and energy consumption. Cities consume vast quantities of resources.

[00:19:28]What rural will be consuming in a very long duration cities will be consuming in a month or a week also. and vast quantities of resources and energy to sustain their dense populations and infrastructure.

[00:19:43]High demand urban areas have a much higher per capita much higher per capita consumption of natural resources like water and energy compared to rural areas. Compared to rural areas, fossil fuel dependence is also very much high in the urban setups. Many cities rely heavily on fossil fuels for energy and transportation driving up greenhouse gas emission and contributing to climate change. Extensive infrastructure is required. The extensive infrastructure needed for sprrowing developments requires significant quantity of material and energy input for both construction and materials. So the requirement of energy is continuously increasing in the urban setups. And similarly when the energy demand is increasing the resource consumption is also continuously increasing.

[00:20:36]So here this slide shows you the increased consumption of resources and energy due to urbanization. So if we talk about energy we need a lot of energy to drive our transportation sector. We need a lot of materials and resources to provide food to everyone.

[00:20:56]Similarly you can see water a lot of water demand is increased very much very high water demand is there materials are needed because we need such buildings such constructions were so materials or raw materials are continuously needed and all these process is energy intensive they need all these processes in the left panel need a lot of energy to continuously go on to continuously work so in conclusion what happens urbanization ation presents both significant environmental challenges and opportunities for sustainable development. Definitely we agree with the fact that urbanization is required.

[00:21:38]People need to uplift their living standard from the rural setup to the urban setup or the semi-urban setup. For the development is definitely required but that has to be sensible development. So addressing the negative impacts require a multifaceted approach interdisciplinary approach that integrates a sustainable urban planning green technologies and effective waste management strategy. So these are some of the mitigation or management strategies which can be followed for a planned urbanization. As urban areas continues to grow, it is crucial to balance economic development with environmental conservation to create resilient cities for the future.

[00:22:34]Environmental conservation and resilient cities means they can survive the pressure of the increasing population.

[00:22:42]They can supply to the demand of the increasing population without compromising the environment.

[00:22:51]Here you can see some of the management strategies which you can follow.

[00:23:05]to make a a planned urbanization.

[00:23:09]Sustainable urban planning is required where green patches having environmental features of clean air, water, soil, all these things should be there.

[00:23:35]grade good parks semi-urban forest and all these things can be planned in this way. So this particular thing will decrease the load on the urban setup in terms of heat development. The heat island will not be developed so much.

[00:23:50]Green technologies of energy can be like shifting towards solar panels, windmills and other green energy or renewable energy sources. Fossil fuels should be minimized.

[00:24:06]Decrease dependency on fossil fuels should be done. Proper waste management should be there. What is biodegradable?

[00:24:19]What is recyclable?

[00:24:23]All these things should be segregated properly and all such things should be managed properly. So if we take a holistic overview of such kind of an urbanization where such things are integrated together, sustainable or renewable energy planning should be there, recycling should be there, biodegradable materials should be used, more and more user-friendly or environmentfriendly material should be used in construction in developing cities or more and more uh green patches like urban forest, urban parks, uh conserved areas as greener areas, better means of transportation, better fuel, vehicles with better fuel efficiency and all these things are taken into consideration. Definitely a proper management system can be developed and a environmentfriendly urbanization can be achieved. In totality, urbanization is definitely posing a great challenges.

[00:25:22]But with these management strategies in our hand, we will be very much able to manage the urbanization, plan the urbanization. And if such planning is done properly and accordingly the it is executed, definitely urbanization will not lead to severe environmental consequences. These are some of the references which you can consider for studying more about urbanization and its effects on urban environment and how these urbanization effects can be managed. Thank you.