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Sustainable ArchitectureProf. Avlokita AgrawalDepartment of Architecture and PlanningIndian Institute of Technology, RoorkeeLecture – 07Environmental Impacts of Development: Impacts on Land and AirGood morning, welcome to online course on Sustainable Architecture and this is week 2,today we are looking at the lecture 2 of week 2. In the previous lecture we discussedabout the impact of development on water, the water element of natural environment.Today we will be discussing about the Impacts of Development or built environment onLand and Air as the allowance of natural environment(Refer Slide Time: 01:04)Starting with the impacts on land the 5 major impacts on land of built environment thathave been identified are desertification, habitat fragmentation, habitat destruction, landdegradation and urban heat island which we commonly know as UHI. Let us go overeach one of these. So, the one of the most important and negative impacts of builtenvironment on natural environment is of desertification. (Refer Slide Time: 01:47)Desertification is the process of conversion or transformation of fertile land into a desert,which is typically the result of deforestation, drought or inappropriate agriculture.(Refer Slide Time: 02:09)Every year if we look around the earth besides the existing deserts which are there,which are because of their geographic location and the soil quality and lot of otherfactors many new deserts are being created where the lands have eventually turnedbarren and are further turning into desert, which to an extent becomes an irreversibleprocess. So, more and more of the fertile land if it converts into desert there by hampering the productivity and the possibility of providing food for the entirepopulation. So, we are looking at a very severe impact on land which is desertification.(Refer Slide Time: 02:57)Now, how is desertification caused because of the built environment? Now the causes ofdesertification which are identified have the major cause as human activities, humanactivities like animal grazing, deforestation, agriculture and urban settlements besidesthese human activities the climatic variations have also a role to play.Now, as we have seen yesterday in the previous lecture on impact of built environmenton water, we had seeing that even the water cycle is altered due to human intervention.So, to some extent the climatic variations are also impacted by human activities orhuman interference into the natural system. Here we are looking only for the causes ofdesertification which are a direct result of human activity.Let us go over each one of them, first is animal grazing; the increasing use of pasturesfor grazing animals and inappropriate grazing, irresponsible grazing, is rresponsible forland degradation, first the land degradation and eventually resulting in desertification.Because, these animals they eat up all the live stock the plant the plantation the greeneryof the pastures there by leaving the soil vulnerable to be eroded by wind as well as waterand gradually converting this pasturesthese pastures into deserts. Deforestation is anothermajor reason now deforestation is simply because of the expansion of art settlements ascities, towns, villages. Since population is growinggrowing, we need more and more of the land to make ourhouses to build our houses, we need more land to cultivate. Now, these forests are beingcut down, deforestation is happening at a very fast pace to pavey way for all these allthese needs for acres and acres of forests are being burnt or cut down to pavey way formanicure plantations which humans are making.For example, palm oil plantation, now because of all these reasons the forest cover of theentire world has substantially reduced. And, it is reducing every year day by day there byleading more and more land towards desertification. Next is agriculture, an inappropriateor improper agricultural practice often leads towards abandoning or leads to barren landswe will see how agriculture is responsible for desertification. And the last one is urbansettlements.A lot of urban settlements in the previous yesterday’s lecture we had seen how an entiresea has dried up Aral seaAral Sea has totally dried up because the urban settlementdevelopment came along the streams which were feeding Aral seaAral Sea. Similar thingis happening to other regions as well when the water streams are blocked, when thenatural course of water is not available to recharge the ground to support the greenery,the flora and fauna that is how the lands are converted into deserts.There are some very classic example: if you go to Jaipur one of the dams which use tosupply to the entire city of the Jaipur has the reservoir of that dam has stopped receivingwater simply because a lot of new settlements were planned in the catchment area ofreservoir. Now, because of this the water is blocked from reaching the reservoir andthere is no water available downwards the areas which were supplied visual fed by thedams, similar things similar kinds of wrong practices, wrong planning of urbansettlements leads towards desertification. (Refer Slide Time: 07:24)Now what are the areas which are most affected by desertification, as we have alreadyseen the causes for the desertification these areas directly respond to those causes. So,the most affected areas are first the irrigated croplands whose soils are often degraded bythe accumulation of salts. Now this accumulation of salts and subsequent desertificationwill happen because of couple of reasons, one where over cultivation is happening, twowere excessive use of pesticides and fertilizers is happening and third were wrong choiceof fertilizer is been made where the fertilizer which was not good for the soil is beingused which promotes the accumulation of salts in these irrigated croplands.The second area is the rain fed cropland which experiences unreliable rainfall and winddriven soil erosion, now that is largely because of the climatic variation, here also wrongpractices of agriculture are responsible for the desertification. Next is grazing landswhich are harmed by overgrazing now these animals who graze on the graze land thepastures they consume plants down to the ground there by totally stopping the growth ofthe plant the tree and there by gradually year after year reducing the green cover whichactually holds the soil and moisture in it and eventually leading it to desertification.And the last one is dry woodlands which are plagued by the overconsumption of fuelwood. So, areas woodlands which are close to the human habitation specially theunderprivileged human population they are at a greater risk of desertification becausethese woodlands are being consumed as the firewood and since the population is increasing this over consumption of firewood is leading towards desertification. Now,that we know the causes of desertification and also the areas which are effectedaffectedby desertification.(Refer Slide Time: 09:49)Let us look at what are the effects of the desertification? What desertification doesbesides converting a fertile land into a barren land, what desertification does? So, the soilerodes or disappears from the place, water becomes scarce or is threatened because thesoil loses it is moisture.So, water table goes further down and since the soil is eroded along with the water thereis less of percolation and the water becomes scarced, because of these two reasons sincethe eroded soil cannot support the plants, vegetation and also water is scarce thebiodiversity declines all flora and fauna is reduced in these areas which is an effect ofdesertification and desertification in itself.So, what are the solutions? First and foremostforemost, solution before I go into thesemicro solutions first and foremost is to plan our habitat plant our cities settlements in away that the natural environment is not impacted affected, all the causes that we haveseen we take care of those causes through appropriate solutions. Now we saw the causeas improper, inappropriate agriculture, so the solutions. (Refer Slide Time: 11:25)We can use salt traps where the soils are rich in salts this soil traps actually consist of awide layer of gravel beneath the soil the top most layer of the soil and that controls saltfrom coming up to the top and converting the land into a barren land. The second isimprovement in irrigation excessive irrigation has often led towards washing away of thetop soil. So, improvements in irrigation for example, the one seen on the screen thispicture such cost effectivecost-effective irrigation improvements they help prevent saltaccumulation and also reduce the loss of water from the soil loss of moisture from thesoil because of evaporation.Other solutions to the wrong practices of agriculture are using cover crops to cover thebarren land often after the crop has been harvested the main cash crop has been harvestedthe farm land lies vacant and it is exposed to wind and water, instead of that cover cropscan be used which prevent the soil erosion and they provide a cover these crops are suchcrops which quickly grow and they can be harvested faster. (Refer Slide Time: 12:57)Next is crop rotation, if you remember in India we always had the traditional policy thetraditional way of farming always had the policy of crop rotation, all of you might havealready seen this particular picture.(Refer Slide Time: 13:13)Where the 4 types of crops the legumes, the alliums, the root crops and brassicas areplanted on a field in a rotation manner, this allows the soil to regain it is strength,sometimes nitrogen is replenished, sometimes other minerals are replenished and that ishow the soil continues to remain fertile there is no over exploitation of one particular nutrient and different nutrients replenished and are used by crops in a rotational manner,besides the solutions to agriculture because agriculture is major threat to desertification.(Refer Slide Time: 14:02)If you look at other causes for example, grazing so, there is rotational grazing as asolution instead of using the same land for rotation year after year we can change, we canrotate the grazing pastures. India traditional Indian settlements had a very beautifulpractice of rotational grazinggrazing. Our are villages whenever the crops whereharvested. So, each piece of land was rotated and animals were left on these pieces oflands for grazing, they would graze they would eat up the left outleft-out portion of theplant which was left on the land after grazing after harvesting.Now this ensured that the stock the waste of the agriculture was not used for burning as afuel it was taken a by animals and when animals stayedtaid on a particular piece of farmland it also fertilized the land through the defecation through the dung that the animalsproduced. So, it was a win-win situation and this way the grazing pastures were alsorotated within the limits of the settlement within the limits of the village.Now unfortunately we have stopped that practice all the farmlands cultivated year afteryear, season after season and there is no place which is left for the cattlescattle, theanimals to graze or in certain cases specially the crops are grown for the animals to betaken up to be eaten which I say as the cover crops. The second solution to desertification is terracing, which involves the creation ofmultiple levels of flat ground like steps. So, we have seen that happening in hills, buteven when in plains where there is a very minor slop terracing can be a very good way ofpreventing soil from getting eroded, because we would this wayway, we would stop thewater from flowing at a greater speed.The next is contour bundling; now contour bundling involves the placement of lines ofstones which act as a barrier to the flowing water of flowing wind and there are windbreaks.(Refer Slide Time: 16:44)The wind breaks for example the one which is seen here the trees are planted as windbreaks in between the farmlands, now these wind breaks this trees the break the speed ofwind and hence the erosion of soil from the farmland, even when it is not covered bycover crops this one is a contour bundling.Now, this contour bundling is with the help of rocks, builders, stones, now this stops thewater this breaks the speed of water even when there is a there is erosion of soilhappening because of flowing water. So, it breaks the soil gets accumulated and only thewater flows there by reducing the loss of nutrients from the soil. (Refer Slide Time: 17:39)Another solution which is directly related to the human habitation and the settlement isdevelopment of appropriate technology for consumption of fuel wood. So, more efficientmanners like the creation the formation of briquettes using the agricultural waste whichcan be use in stoves.Also the plantation specific plantation which can be grown on the boundaries towards theboundaries of the deserts for example, jojoba plantation this is a hardy tree which growsin arid and semi arid areas and requires very less of moisture to grow and it helps the soilto regain the moisture and it also changes the micro environment micro climate of theplace.So, such similar species have been identified one of which is jojoba and this can helpreverse the process of desertification on the adjoining the boundary layer of the desertswhich are been created, the second and third impact of built environment on land as anatural element. (Refer Slide Time: 18:53)They are habitat fragmentation and habitat destruction, now because of hugeinfrastructural projects which are being carried out world over, the habitats are beingdestructed they are being fragmented. This particular image on the screen is of the oilpalm estate in Malaysia; here an entire patch of rain forest has been cleared to pay wayfor oil palm estate and majority of the oil palm plantations in South East Asia they arecoming directly at the cost of rain forest clearance.Rain forest clearance implies the destruction of habitat for all the specie we are not justlosing out on plant speciespecies, but we are losing out on the habitat of a number ofanimal animals, insects, birds who were residing thriving in these rain forests there bydestructing their habitats.There is habitat fragmentation the roads are passing through jungles, forests and animalsthe habitat for animals are fragmented. So, if 100 square kilometer of an area is requiredfor one family of lions to survive and the entire life stock entire stock of animals in thatarea form an eco system when a road passes to through that forest dividing it into 50acres of each for one family of lions it is only 50 acre available.We may not think that way we may still think that it is just road passing by the animalscan also cross the roads, but it unfortunately does not happen that way with the animalsand that is why their habitats have been fragmented, they come in direct contact with humans with the transport systems and there by further leading towards extension ofthese species these animal species.(Refer Slide Time: 21:13)Entire habitats, forests are in the process of getting destructed simply because of the so,called developmental projects, because we need more land for developing are cities andwhat happens to the animals to the biodiversity to the organisms living creatures who areresiding in these forestthese forests. They are forced out of their own habitat, they aredisplaced, they are at times destroyed, they become extinctent and endangered simplybecause of this habitat destruction.Across the world efforts are being put in to preserve the habitats from getting destructedif they have been identified as the habitats for certain species mainly the endangeredspecies, but unfortunately the species which was still large in number on earth as on dateare not being considered while destructing their habitats the natural habitats. (Refer Slide Time: 22:31)Another impact on land is land degradation; land degradation is the first step towardsdesertification. So, majority of the causes which lead towards desertification are also thereasons which lead towards degradation, which is overgrazing, which is wrong practicesof cultivation, faorming, which is wrong use or over use of forest deforestation. So, thesame causes also cause land degradation which subsequently result in desertification.(Refer Slide Time: 23:12)So, the reasons for land degradation and which also further leads to land contaminationincludes deforestation, a land clearance, agricultural depletion of nutrients from the soil, overgrazing, inappropriate irrigation, urban sprawl and commercialized development,contamination of soil and acidification of soil because of setting up of industries anddumping of this waste into the soil, soil erosion, loss of carbon from the soil because oferosion, vehicle off roading where the fuel petrol or diesel is getting into the soil becauseof the vehicles which are off roaded, querying of stone or minerals mining in general isanother major reason for land degradation and land contamination.Increase in the size of field due to economies of scale, reducing shelter for wildlife andas hedgerows and copses they disappear that is another reason now for majority of theseproblems the reason the bottom line the core reason is that human population has beenincreasing, we are not controlling are population, we are not limiting it and we are notlimiting our needs, we are becoming more and more of a consumer of consumerismsociety were we need more and more of products produced for fulfilling our needs.We need more food, we need more industrial products instead of the life style where werequired less we now need more and all of it we can notcannot consume we waste moreand for all of that we again need soil for growing more and for dumping that waste backin to the soil.(Refer Slide Time: 25:30)The last one is urban heat island or UHI, urban heat island is a city or metropolitan areathat is significantly warmer than it is surrounding rural areas due to human activities.Now what kind of human activities result in urban heat island and how? So, if you look at the causes hard and darker surfaces lead towards urban heat island, now how is urbanheat island caused? During the day when solar radiation receives the surfaces thesesurfacessurfaces, they absorb certain amount of heat some part is reflected back andsome part is absorbed depending upon the material property.Now, this heat which is absorbed since it is constant in the night time when theenvironmental temperatures outdoor temperatures are low, this body this surface whichwas at a higher temperature which is at a higher temperature because of higherabsorption of all that heat will now reradiate this heat. Now, this reradiated heat istrapped in the atmosphere and that is what causes the atmospheric temperature during thenight time to increase this is the phenomena of urban heat island. Now, what kind ofsurfaces, what kind of materials will store more heat and will reradiate this heat hardsurfaces and dark surfaces.If you look at a grass lawn and if you walk on it during the day or night do you feel thechange in the temperature of the surface not really not much. However, if you walk on apaved road during the morning hours and during the evening hours when the sun hasalready fallen on the surfacesurface, we feel that difference in the surface temperature,that is simply because the surface the material has absorbed lot of heat because it havethe capacity.So, majority of the materials which have been used in a cities are hard materials theyabsorb a lot of heat unlike our villages in traditional times where the village the homes inthe villages the huts were made out of mud, earth and organic materials like weeds andreeds now they did not absorb heat, there capacity to absorb heat is much lower theyreflect more and that is why not only the hut would remain cooler, but also thesurrounding environment would remain cooler another material for example, is plantitself.Now, if there is solar radiation which is falling on a plant or a tree it would absorb theradiation and use it for making it is own food instead of absorbing it and reradiating inthe night the plants do not do that. UnfortunatelyUnfortunately, in a cities the plants arereducing we hardly have green cover, we only see a lot of hard surfaces the vertical hardsurfaces, the horizontal hard surfaces and that is why there is an increase temperature.There is also a lack of moisture there is less of evapotransperationevapotranspirationwhich is happening because of lesser number of trees which are there the greenery whichis their together with increase surface area for reflection and absorption of sun lightwhich is also called the urban canyon effect, blocking of wind because of the urbanmorphology which is there.All these 4 reasons lead to an increase in the temperatures of the urban area the urbansettlement. Now because the temperature has increaseincreased the energy which isrequire to create comport inside the buildings through the use of air conditioners andthrough the use of air conditioned auto mobiles on roads the anthropogenic heat from thehuman activities that further increases leading to an addition of temperature increasefurther increase of temperature.Another reason of urban heat island is high levels of pollution, all these vehicles andindustries which emit the green housegreenhouse gasses they absorb more and more ofheat and thereby making our micro environment micro climate hotter warmer.(Refer Slide Time: 30:23)All of this leads to the loss of bio diversity, growth of non native species which we havealso seen as alien invaders, altering the local wind patterns, development of clouds andfog which are localized. So, we see smog in daily what we do not see it as we move outof the NCR region when we go towards less urbanized areas. Varying rates of humidityand precipitation, additional shower and thunderstorm activity, because of the negativepressure which is created and there are some socio social impacts like increase mortality rate in children, increase temperature of water bodies further leading to consumption ofenergy for creating comfortable environment inside buildings and how can we mitigate?The very simple answer to that is increasing the vegetation more and more trees andgreen surfaces should be maintained to reduce the urban heat island impact because theywill be lesser absorption of radiation. The second important thing is using high albedoand reflecting material, materials which reflect more they directly reflect the radiationinstead of absorbing them such materials should be used for example, light colouredsurfaces, smooth surfaces on the top of the buildings.(Refer Slide Time: 32:03)Third mitigation measure is to use pervious layers to allow water peculation if we havevery hard paved surfaces roads, they allow for less and less moisture there by reducingthe evapotranspiration which further increases the impact of urban heat island. And,reduction in anthropogenic heat through policies like carpooling or improving increasingthe efficiency of equipment that is been used in homes through such measures we canreduce the urban heat island in our cities. (Refer Slide Time: 32:40)The next we have is impacts on air, this was a protest against the falling quality of air athighland park optimist club wearing smog gas masks at banquet, people started realizingand today we are more aware of how the air quality is changing we know what is thequality of air yet there is not much effort towards improving the quality of air the air isactually becoming poisonous.(Refer Slide Time: 33:22)If you look at this map the world map it clearly shows the quality of air across the worldand we see particularly Asia and Africa as the most polluted having the most polluted air, if you look at the W.H.O. guideline values for the quality of air we realize that largepart of the world actually does not have clean air to breath currently. So, what are thefurther impacts air pollution?(Refer Slide Time: 34:01)Now, this is because of human activities only one we are cutting down trees which canreduce the amount of pollution that is present in the air through absorption plants andtrees they absorb a lot of different hazards, chemicals which are suspended in the air.So, the trees, the tree cover is reducing and simultaneously the pollutants are more andmore pollutants are be added into the air through our industries, through our transportsystems, through the use of equipment for creating comfortable environment inside ourbuildings, all of them leading to more and more green house gas emissions, more andmore ozone deplete things substances, more and more substances which have a higherglobal warming potential all this together is leading towards air pollution. (Refer Slide Time: 35:08)Now, because of air pollution air pollution itself is a huge problem because of airpollution there are further problems which arise for example, acid rain, global warmingand climate change these are inter related they are impacting each other, ozone damage,the problem of smog in cities, health problems which are the social problems forexample, skin cancer, respiratory diseases, they are increasing because of air pollution.The loss of eco system because of air pollution, loss of flora and fauna and ultimately itis a effecting these supply of food and the quality of food which is available to thehuman kind.(Refer Slide Time: 35:59) What are the on the health of air pollution, we have more and more specifically in Indiawe are more and more cases of bronchitis, children right from the early ages areeffectedaffected by asthma and there is an increasing number asthma symptom days forchildren in the ages of 5 to 19. There are additional cases of illnesses that lead directlylead to impact the work activities normal work activities there by not just impacting thehealth, but impacting the economy.(Refer Slide Time: 36:40)(Refer Slide Time: 36:44) (Refer Slide Time: 36:45)(Refer Slide Time: 36:48) (Refer Slide Time: 36:53)There is a greater impact of air pollution on human body as listed and besides that wehave a lot of investment which is going towards the health care which is because of airpollution. So, the welfare costs are increasing if we look at the welfare costs in differentcountriescountries, we see that with higher air pollution greater air pollution they spendmore towards the welfare costs.So, such are the impacts of impacts on air because of the built environment. If we look atthe impacts of built environment on water, land and air collectively where we realizeairlies that there is not a single impact which is not there, because of human intervention,everywhere human activity is have led to pollution contamination loss of eco system andin the end all of this is leading to some or the other socio cultural problem.I will conclude this lecture here and in the next lecture we will look at the socioculturalsocio-cultural impact of built environment. So, it is not just on naturalenvironment as I said in my introductory lecture I will repeat it again that we are notworried of the impacts are activities have on the natural environment, we have worried ofthe impacts that this degradation of natural environment has on us as human beings, weare worried of the socio cultural impacts this development and this loss of naturalenvironment has on human kind, see you in the next lecture.Thank you.

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