CITY PROFILE: SURAT. Concept of Urban Heat Island effect in Indian cities

CITY PROFILE: SURAT Concept of Urban Heat Island effect in Indian cities

Promoting Cool Roof and Passive Ventilation concepts for indoor thermal comfort An Initiative under ACCCRN Urban Heat Profile: Surat City Prepared by: Dr. Umamaheshwaran Rajasekar Ashish Mishra Submitted by:

Contents Summary... I Urban Heat Island:... I Indore and Surat Heat Profile:... I Cool roof and Passive ventilation options:... II Chapter - 1: Urban Heat Island in Indian Cities... 1 Indore City... 2 Urban Heat Profile of Indore... 3 Surat 5 Urban Heat Profile of Surat... 6 Urban Heat Island Mitigation Strategies for Indore and Surat... 8 Chapter - 2: Urban Heat Profile of Surat... 9 Demographic and geographic profile of the city... 9 Hypothesis... 9 Description of the Instruments Used... 10 Methodology... 10 Criteria of the Chosen Area... 11 Data Analysis... 13 Conclusion... 20 Lessons Learnt... 21

Summary Cool Roofs provide a thermally comfortable indoor living environment, while reducing the energy consumption and increasing health benefits for the occupants. Due to urbanization, densely populated areas get more heated in comparison to the areas with low density or sparse population. A cool roof is designed to maintain a relatively lower surface temperature during extreme heat than a traditional roof Passive Ventilation is a way to increase the indoor thermal comfort of the building occupants and to improve the indoor air quality without using any electrical or mechanical energy. Passive ventilation is an integral part passive cooling design. It covers all the possible measures and processes which help in reducing the cooling needs of the buildings with limited/no use of external energy source. Urban Heat Island: A swathe of population migration towards urban centres and increase in urban population has led to rapid change in the land use and land cover within cities and resultant increase in traffic congestion and pollution. Scientists have observed that air temperatures in densely built urban areas are higher than the temperatures of the surrounding rural country. This increase in temperature within urban areas is known as the urban heat island (UHI) phenomenon. Different mitigation strategies are suggested by different experts in the field of urban planning, architecture, natural resource management and transportation. These mitigation strategies have an impact on both local and global climates. In addition to environmental benefits, these mitigation strategies also help in reducing the energy consumption for cooling and increase the thermal comfort of the poor people who suffer most in the heating summers. Indore and Surat Heat Profile: Due to their geographical locations Indore has a moderate to extreme climate while Surat has mild to warm climate coupled with high relative humidity due to its proximity to the Arabian sea. The city heat profiling developed a model to estimate the future temperature scenario of both the cities. It was observed that since Indore and Surat fall in separate climatic zones in India, it is imperative to adopt different interventions to mitigate the urban heat island effect. Indore, having a clear sky during summers, receives very intense solar energy. Therefore, roofs should be designed in such a way so as to reflect most of the solar energy back in the atmosphere. While in Surat, warm and humid region, the main design criterion should focus on reducing heat gain by providing TARU Surat City Profile I

shade, and promote heat loss by maximizing cross ventilation. Dissipation of humidity is also essential to reduce discomfort. Cool roof and Passive ventilation options: Cool roofs and passive ventilation solutions should be adopted as roofs make a huge contribution in solar energy absorption and passive cooling techniques are the most economical solution to increase thermal comfort for the poor people in a developing country like India where most of the buildings are not thermally insulated. Apart from increasing thermal comfort, cool roof and passive ventilation provide a range of benefits. Climate change mitigation through reduced energy consumption, urban heat island mitigation through cooler ambient air temperature, lower ambient air temperatures and the subsequent improved air quality also result in a reduction in heat-related and smog-related health issues, including heat stroke and asthma to name a few. TARU Surat City Profile II

Chapter - 1: Urban Heat Island in Indian Cities As climate change is affecting the whole world, Indian cities are also seeing the increase in the summer temperature and heat waves. India s building sector is expected to increase 5 times from 2005 to 2050 and it consumes almost 30% of the energy produced in India. India s energy demand is projected to double or triple by 2030. India already imports 68 percent of its oil, 25 percent of its natural gas, and 13 percent of its coal, according to the Energy Information Administration. Energy demand is not able to match up with the rapid growth in urbanization and population which increase the energy consumption. Energy efficiency is the only way to reduce the gap between them as more energy production is a costly affair and a burden over the power plants. Complete blackout in 17 states of India in July 2012 reveals the energy crisis in India. According to the 12th five year plan, India must increase its energy production by 6.5% annually from 2011 levels to maintain the 9% growth rate. 1 After seeing this complete blackout twice in a month, Delhi government decided to make the capital city more energy efficient. To deal with energy crises, Delhi government directed all the building construction and maintenance agencies to implement cool roof technologies 2. Few other states like Gujarat, Andhra Pradesh, Rajasthan, Tamilnadu etc. also initiated green roof, cool roof and passive ventilation technologies. Adaptation of these energy saving technologies will help in reducing the urban heat island effect by removing the AC units from the buildings. A study from Indian institute of Science (IISc) Bangalore indicates that India will experience 1.7 to 2 0 C rise in the temperature (in comparison to preindustrial level) by 2030 3. UNFCCC describes that more than 2 0 C rise in temperature is dangerous and India may breach out this limit by 2030. Following figure shows the maximum temperature attained by different cities in peak summer. Indian cities need to address the urban heat issues immediately as most of them have the average maximum temperature of 35 0 C and they are using more energy for air conditioning in summers. In spite of low per capita consumption, the increase in population combined with an increase in affordability and aspiration among urban residents has led to the increase in total energy demand. This drastic increase in energy demand has led to poor quality of electricity supply (fluctuations) and, frequent power cuts due to shortages. Power cuts are more common during 1 Planning Commission, Draft Report: Faster, Sustainable andmore Inclusive Growth, An Approach to the Twelfth Five Year Plan (2012-17), Government of India, Aug. 20, 2011, http://planningcommission. nic.in/plans/planrel/12appdrft/appraoch_12plan. pdf. 2 http://www.indianexpress.com/news/-cool-roofs--mandatory-for-all-new-buildings/988898 3 http://articles.timesofindia.indiatimes.com/2012-09-09/special-report/33712992_1_climate-change-climatemodels-cancun-agreement TARU Surat City Profile 1

summers especially due to climate control loads. The peak demands during summers impact livelihoods and cripple the daily life especially in urban areas. This situation also imposes a heavy burden on India s growing trade and industry sectors. With the energy costs growing over years and expansion of urban heat islands of cities, there is a need for conserving energy with improvement of thermal comfort to the residents. Indore City Fig.20 Maximum Temperature Isopleths The population of the Indore increased from 57 thousand in 1911 to 16 lacs in 2011. Decadal growth rate has been around 40% which is higher than the national growth rate of 22%. Being an educational, medical and trade hub of Madhya Pradesh, Indore is seeing a lot of migration from rural areas. Population of Indore is expected to be 3 million by the year 2021 (IMC). TARU Surat City Profile 2

Rapid spread and densification of the Indore city has occurred over the period of time. Patterns of land use land cover change of the past four decades indicate growth being guided by the socioeconomic processes which include population Fig 21 Indore growth, City Growth economic development, trade, intellectual capital, location advantage and migration. As per the real estate planners, about 100,000 additional houses are required annually to meet the growing housing demands of the city. With the increase of more built up area in the coming years and reducing the green area in the city, the problem of urban heat island is expected to intensify. As 27% of the city s population live in slums, almost one third population of Indore city suffers from the temperature increase due to overcrowded settlements, low ventilation and poor vegetation cover. Since most poor cannot afford space cooling devices beyond fans, nor the increasing costs of electricity, they are likely to be impacted differentially. Urban Heat Profile of Indore Due to its location in Central India, Indore has moderate to extreme climate. The average annual maximum temperature of Indore is around 33 0 C. In winter especially during the months of December and January, the nighttime temperature drops to around 10 0 C while the daytime temperature is usually over 25 0 C. During summer especially during the months of April to June the Maximum temperatures can be over 40 0 C. Minimum and maximum temperature can go up to 30 0 C and 45 0 C respectively on an annual basis. Due to its location on the southern edge of the Malwa Plateau, in spite of experiencing hot temperatures during the day, the evenings and night are cool with the temperatures dropping to 25 0 C. The figure below provides an illustration of average maximum and minimum temperature between the periods 1961 to 2000. TARU Surat City Profile 3

Temperature (c) Temperature (c) 45 40 35 30 25 20 15 10 5 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1961-2000:Max 1961-2000:Min Figure 22: Indore Observed Temperature Future Temperature Analysis: 2021-2100 45 40 35 30 25 20 15 10 5 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Observed: Max Observed: Min A1B Max A1b Min Figure 23: Indore Future Min and Max Temperature: 2021-2050 TARU Surat City Profile 4

Temperature (c) Temperature (c) 45 40 35 30 25 20 15 10 5 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Observed: Max Observed: Min CGCM3: Max MPI:Max MPI- Min CGCM3: Min Figure 24: Indore Future Min and Max Temperature: 2046-2065 45 40 35 30 25 20 15 10 Figure 25: Indore Future Min and Max Temperature: 2071-2100 The results in general indicate that irrespective of the scenarios, the minimum and maximum temperatures are likely to increase in the city. During near term, i.e. for the next three decades this increase may be of the order of 0.5-1 0 C in maximum temperature and around 3-4 0 C in minimum temperature. In the later part of this century i.e. beyond 2040, the temperatures are likely to increase in the range of 2-4 0 C in maximum and minimum temperatures respectively. If the scenario projections take shape then cool evening temperatures will no longer be applicable to the city as the minimum temperature are likely to increase more rapidly in comparison with the maximum temperature and the diurnal temperature difference of 10-15 0 C is also likely to decrease. Surat 5 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Observed: Max Observed-Min A2: Max B2: Max A2: Min B2: Min Surat is the 8 th largest city in India. As per the census 2011, Surat has a population of 4.46 million. Many people migrated to Surat city due to the presence of huge textile and diamond industry. The city saw an unprecedented growth in the last four decades, recording one of the highest growth rates in the country and a 10-fold population rise over four decades. The city area has expanded with time (major expansion being in 2006) and presently covers 326.515 sq.km. The population of Surat is expected to grow from 4.46 million (2011) to 6.4 & 8.5 million by 2021 & 2031. TARU Surat City Profile 5

1963 1975 2004 2006 Fig.26 Surat City Growth Fig. 27 Population Projection of Surat Urban Area Urban Heat Profile of Surat The temperature of Surat is mild to warm with the summer time maximum temperatures averaging to 34 0 C while the winters are relatively cool with the nighttime temperatures averaging to around 14 0 C. In peak summer, the maximum temperature can go up to 44-45 0 C. TARU Surat City Profile 6

Temperature (c) Temperature (c) With its proximity to the Arabian Sea, the relative humidity of the city is high. The observed average temperatures of the city across the months are presented in the following figure. Figure 28: Observed Historical Temperature 40.0 35.0 30.0 25.0 20.0 15.0 10.0 5.0 0.0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1961-2000 Max 1961-2000 Min The model estimated future temperature for the years 2021 to 2100 are presented in the following figure. From the figures, it is evident that there may not be a drastic change in average temperature (both minimum and maximum) but with little possibility of increase during the pre-monsoon and post-monsoon seasons. The results indicate the in the next few decades the minimum temperature may increase by around 3-4 0 C leading to the winter minimum temperature being around 20 0 C instead of the current 15 C. Further, the maximum temperatures are showing possible increases and may rise beyond 35 0 C. Since Surat is a coastal city, the relative humidity is usually very high. With the temperatures increase, the thermal comfort of the city may decrease drastically forcing people to opt for artificial cooling systems. Such a shift in lifestyle may lead to more energy and water demand. 40.0 35.0 30.0 25.0 20.0 15.0 Figure 29: Estimated Temperature: 2021-2050 10.0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Observed-Max Observed-Min A1B-Max A1B-Min Figure 30: Estimated Temperature: 2046-2065 TARU Surat City Profile 7

Temperature (c) Temperature (c) 40.0 35.0 30.0 25.0 20.0 15.0 10.0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Observed-Max Observed-Min CGCM3-Max CGCM3-Min MPI-Min MPI-Max CNRM-Min CNRM-Max 40.0 35.0 Figure 31: Estimated Future Temperature: 2071-2100 30.0 25.0 20.0 15.0 10.0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Observed-Max Observed-Min A2-Max B2-Max A2-Min B2-Min Urban Heat Island Mitigation Strategies for Indore and Surat As Indore and Surat fall on two different climate zones in India, different interventions should be adopted to mitigate the urban heat island effect. Indore lies in the composite climate zone and Surat comes under the hot and humid climatic zone 4. The main design criterion in the warm and humid region is to reduce heat gain by providing shade, and promote heat loss by maximizing cross ventilation. Dissipation of humidity is also essential to reduce discomfort. Summer days in Indore have clear skies and buildings and pavements receive very intense solar energy. Roofs should be designed to reflect most of the solar energy and for this purpose glazed tiles, cool paints etc. can be used. Composite climate regions experience high humidity in monsoon season so new buildings should be designed to maximize the cross ventilation which will help them to remain cool when other mitigation measures do not work. Adopting these measures will increase the thermal comfort of the building occupants and thus increase the working efficiency. These interventions will also remove the load from the air conditioner units which cannot provide much comfort in this highly humid environment. 4 http://mnre.gov.in/solar-energy/ch2.pdf TARU Surat City Profile 8

Chapter - 2: Urban Heat Profile of Surat Demographic and geographic profile of the city Surat is the 8 th largest city of India with a population of 4.46 million. It is hub of the textiles and diamond industries of India. The city saw an unprecedented growth in the last four decades, recording one of the highest growth rates in the country and a 10-fold population rise over four decades. The city area has expanded with time (major expansion being in 2006) and presently covers 326.515 sq.km. The population of Surat is expected to grow from 4.46 million (2011) to 6.4 & 8.5 million by 2021. 2004 2006 Fig. 44 Surat City growth during 2004 to 2006 (Source: TARU) Surat is a port city situated on the banks of the Tapi river. It has an average elevation of 13 meters. The temperature of Surat is mild to warm with the summer time maximum temperatures averaging to 34 0 C while the winters are relatively cool with the nighttime temperatures averaging to around 14 0 C. In peak summer, the maximum temperature can go up to 44-45 0 C. With its proximity to the Arabian Sea, the relative humidity of the city remains high. Hypothesis Urban heat Island is a phenomenon where urban areas experience warmer temperatures than suburban or rural surroundings. It is observed that temperature variation occurs due to human activity and unplanned, unprecedented growth of urban areas. Open and green space, built up area, traffic density and micro-climatic condition of the particular area can affect the ambient air temperature within that zone. It is aimed to study the effect of above mentioned variables over the urban heat and to draw the urban heat profile of the city. These results will feed into TARU Surat City Profile 9

identifying the hotspots within the city and studying the effectiveness of green and open space to reduce the urban heat island effect. Description of the Instruments Used Data logger used in the study measures and stores up to 16,379 relative humidity (RH) and 16,379 temperature readings over 0 to 100% RH and -35 to +80 C (-31 to +176 F) measurement ranges. This data logger also measures dew point. Dew point is the temperature at which water vapour present in the air begins to condense. It has an accuracy of ±0.5 deg C in temperature and ±3 in %RH. Another data logger was used to continuously monitor the temperature and relative humidity at established reference point A0. It records upto 16000 readings for both parameters i.e. relative humidity and temperature over 0 to 100% RH and - 40 to 70 C measurement ranges. It has an accuracy of ±2 deg C in temperature and ±3 in %RH. A hand held infrared thermometer was used to measure the road surface temperature. It has a measurement range between -50 to 550 deg C. It has a distance aspect (D: S) ratio of 8:1. The D: S Ratio indicates the size of the measurement field that a non-contact infrared thermometer uses to provide a temperature reading. The larger the ratio the better the resolution and the smaller the area that can be measured. An IR Thermometer with a D: S of 8:1 will measure a 1 diameter at a distance of 8 away. Instruments Used in the Study 1. Temperature Humidity data logger (2 different types) 2. Non-Contact Infrared Thermometer 3. GPS Hand held GPS GRAMIN etrex 30 was used to log the location of of the tracks in terms of longitude and latitude. This GPS device can track both GPS and GLONASS satellites simultaneously. It has also ability to add the additional road map which helps in surveying new areas. Waypoint manager helps in marking the location during the survey. Fig.45 Instruments used in the study: LASCAR data logger, IR Thermometer, GPS and EXTECH data logger (starting from left to right) Methodology Different areas within Surat city were selected based on socioeconomic classes. These areas were selected in such a manner so that they are different with each other in terms of socioeconomic way, built up area and geography. As temperature was measured in different locations at different time durations, a data logger was installed at area A0 to record the AAT and relative humidity continuously. This area A0 was used as a benchmark to compare the data obtained from different field locations. A transect was decided in each locality to collect the data. A data logger was used to collect the ambient air temperature and relative humidity at an interval of 10 second. Other data such as type of buildings, density of buildings, building material, traffic condition, type of road and major economic activity of particular TARU Surat City Profile 10

area were collected during the survey based on visual observation. GPS was used to track location information during the survey. Tracking was carried out for an interval of 10 second during the survey. As time is the common factor between all data recorded, data was linked in excel sheets so that ambient air temperature and relative humidity can be obtained at all GPS points. Data was mapped using GIS software Manifold to analyze the data. Ambient air temperature recorded at different locations were compared to the recorded temperature at reference point and data were analyzed to understand the effect of different factors such as built up area, water body open and green areas over the spatial and temporal temperature variation. Criteria of the Chosen Area Six different areas were chosen across Surat city as representative sites for temperature profiling. The selection included the following criteria: Densely built areas Areas with high traffic density Road condition Green areas and water bodies Different socioeconomic groups Different types of building (roof, age and material used) Category of Socioeconomic Group of Surat City 1. Lower Income Class 2. Middle Income Class 3. Upper Income Class 4. Slum area 5. Industrial area 6. Institutional area 7. Mixed Fig.46 Selected areas of Surat city for urban heat profile survey Table.6. Description of selected areas for Urban Heat Profiling TARU Surat City Profile 11

ID A0 A1 A2 A3 A4 A5 A6 Name of the Area Reference Point_Nanpara MTB College Area Lalji Nagar Vegetable Market 80 feet Road Area Ved Road Area L.P.Savani Road Area Description Area in the center of the city, close to the river, High building density and traffic, narrow roads, it is used as a reference point to monitor data continuously Along the river, average G+3 buildings, Low building density and traffic, open area and lot of trees in the locality, Wide bitumen road and huge open space Along the river, mostly G+1, few buildings up to G+11, medium building density and low traffic, wide but damaged bitumen road Vegetable market in the eastern part of Surat, Cemented road, low building density and medium traffic, Very congested during early morning, Southeastern part, G+2 buildings, High building density and traffic, damaged and narrow bitumen roads Northern part, G+1 & G+2 buildings, High Building density and medium traffic, wide but damager bitumen road North western part of the city, G+1, High building density and medium traffic, narrow and damaged bitumen earthen roads Measurements were recorded at an interval of 10 seconds and results were compared with reference data obtained at A0. These six areas spread from core of the city to the periphery of the city. Fig46. shows the selected areas in Surat city for survey. Different colors of the symbol represent the socioeconomic class of that particular area. The collected data were analyzed in detail to assess the heat Island characteristic in the city of Surat. Fig. 47 to Fig 52 show the different areas surveyed during urban heat profiling. Fig. 47. Roads with tree line in MTB College area Fig.48. Building with awnings to reduce sun exposure TARU Surat City Profile 12

Fig. 49 High rise buildings in Surat Fig. 50. Poor Housing without proper ventilation Data Analysis Fig. 51 Vegetable Market Fig. 52 Commercial cum residential area near 80ft road Six different areas were chosen to study the variation of ambient air temperature with time in different micro-climatic conditions. A1 is located near river TAPI in a low dense area having institutions, public offices and open green areas. Mean air temperature of the A1 was observed less in comparison to the temperature at reference point located at the city center. The mean difference was found close to 0.7 deg C with maximum difference up to 1.5 deg C. TARU Surat City Profile 13

AAT of A1 AAT of A2 38 36 34 32 Field data Reference data 36 35 34 33 32 Field Data Reference Data 40 38 36 34 32 AAT of A3 Temperature (Celsius) Field Data Reference Data 42 40 38 36 34 32 AAT of A4 Field Data Reference Data AAT of A5 AAT of A6 40 35 30 25 Field Data Reference Data 38 37 36 35 34 Field Data Reference Data Note: Temperature in Celsius Fig.53 Comparison of ambient air temperature (AAT) between reference point and field locations A2 is located on the other side of the river TAPI opposite to the A1. A2 comprises few high rise buildings up to G+11 with damaged road conditions. It is observed that roads along the river are getting more heated due to a wide open area that also increases the ambient air temperature significantly. Other selected areas for the study consist of the vegetable market, low and middle income housing areas and commercial areas but these areas lie on the TARU Surat City Profile 14

11:18 11:22 11:27 11:31 11:36 11:40 11:57 12:02 12:06 12:11 12:15 12:20 12:24 12:29 12:33 13:58 14:03 14:07 14:12 14:16 14:21 14:25 14:30 14:34 14:59 15:03 15:08 15:12 15:17 15:21 15:26 15:30 Temperature Difference (deg C) periphery of the city. Average ambient air temperatures in these areas are lower in comparison to the reference point temperature data. The maximum temperature recorded on the day was 37.5 deg C Temp.Difference between Reference point & field data A3 A4 A5 A6 7 6 5 4 3 2 1 0-1 -2 Time Temperature difference Fig.54 Ambient Air Temperature (AAT) difference between reference point data and field data (21st March 2013) The above graph Fig. 54 represents the variation of ambient air temperature (AAT) of selected areas with reference to benchmark located at A0. It can be clearly observed that 80 feet road area feels more variation in temperature than other surveyed areas. This huge difference was found due to high building density and high traffic in that commercial and residential area. Congestion of buildings and traffic do not provide the free path for movement of air. Hot air revolves around those buildings and remains heated for a long duration. Location A5 indicated relatively high difference in AAT in comparison to the reference point A0. Temperature difference was relatively high around area with high building denity and relatively low. around open or green area. AAT in A3 and A6 did not differ much in comparison to reference point although these areas differ in local characteristics among each other. It can be assumed that some of the local characteristics counterbalance the effect of other properties. TARU Surat City Profile 15

13:30 13:32 13:35 13:37 13:40 13:42 13:45 13:47 13:50 13:52 13:55 13:57 14:00 14:02 14:16 14:19 14:21 14:24 14:26 14:29 14:31 14:34 14:36 14:39 14:41 14:44 14:46 14:49 Temperature Diference (deg C) Temperature Difference between refrence point and field 1.5 A1 A2 1 0.5 0-0.5-1 -1.5-2 -2.5 Time Temperature difference Fig.55 Ambient Air Temperature (AAT) difference between reference point data and field data (19th March 2013) Fig.55 represents the temperature variation of surveyed areas on 19th March 2013 with respect to reference point locate at A0. The temperature recorded at locations A1 and A2 are higher in comparison to AAT at A0 except for areas having tree lines (Fig.13). Highway along the riverside in A2 area observed a relatively high temperature which may be due to wide open road, congestion of commercial buildings and heavy traffic. Green open areas and water body helps in dissipating the heat at a faster rate. Land areas near a large body of water may not heat up as much as areas that are not close to water, because the water itself is absorbing much of the heat energy. This will cause the climate to be more moderate in summer near the river or large water bodies. Fig. 54 shows lower temperature recorded initially in A1 area although there was no significant change in geographic location or land cover. This variation indicates that data logger takes 2 to 3 minute time to adopt the change in new local environment. TARU Surat City Profile 16

Fig. 56. Urban Heat Profile of Lalji Nagar and MTB College Area on 19th March 2013 (1:30 to 3:30 PM) TARU Surat City Profile 17

Fig. 57 Urban Heat Profile of Vegetable Market and 80 feet road area on 21h March 2013 (11 am to 12:30 pm) TARU Surat City Profile 18

Fig. 58 Urban Heat Profile of Ved Road area and L.P. Savani road area on 21h March 2013 (2 to 3:30 pm) From the above urban heat profile mapping ( fig. 56, 57 & 58) of different surveyed areas, it can be clearly observed that humidity is higher in locations close to river and around greener surroundings. Areas with high temperature and high humidity create much discomfort to working and living condition which can lead to dangerous effect on human health. People can TARU Surat City Profile 19

be susceptible to heat cramps, heat stroke and other health disease. A 34 deg C temperature will feel like 41 deg C with a relative humidity of 55% (NOAA heat index table). Relative Humidity (%RH) NOAA national weather service: heat index Temperature ( C) 27 28 29 30 31 32 33 34 36 37 38 39 40 41 42 43 40 27 27 28 29 31 33 34 36 38 41 43 46 48 51 54 58 45 27 28 29 31 32 34 36 38 40 43 46 48 51 54 58 50 27 28 29 31 33 35 37 40 42 45 48 51 55 58 55 27 29 30 32 34 36 38 41 44 47 51 54 58 60 28 29 31 33 35 38 41 43 47 51 54 58 65 28 29 32 34 37 40 42 46 49 53 58 70 28 30 32 35 38 41 44 48 52 57 75 29 31 33 36 40 43 47 51 56 80 29 32 34 38 41 45 49 54 85 29 32 36 39 43 47 52 57 90 30 33 37 41 45 50 55 95 30 34 38 42 47 53 100 31 35 40 44 49 56 Fig.59. NOAA national weather service: heat index (Source:NOAA) Caution (fatigue is possible with prolonged exposure and activity. Continuing activity could result in heat cramps) Extreme Caution ( heat cramps and heat exhaustion are possible. Continuing activity could result in heat stroke) Danger (heat cramps and heat exhaustion are likely; heat stroke is probable with continued activity) Extreme Danger (heat stroke is imminent) Conclusion The maximum recorded temperature was 40.1 deg C around 12 PM on 21st March 2013. The maximum recorded temperature difference between selected area and reference point was 6 deg C (11:30 AM to 12:30 PM). This may be due to change in land use and land cover at different locations. High humidity was observed in areas near TAPI River. Open space and green areas were observed to have relatively low temperatures in comparison to highly dense residential and commercial areas. Water body and green areas behave as a major heat sink in urban areas. TARU Surat City Profile 20

Lessons Learnt Data loggers used at different sites and reference point should be properly calibrated to avoid data errors. It is recommended to select a building for continuous temperature and humidity recording after classifying the chosen area because steady observation will provide a better understanding of temporal variation of humidity and temperature. More areas should be selected to get a better picture of the city profile. Wind data (wind direction and wind speed) should also be considered in drawing the thermal profile of the city. Pollution study should be included to draw the urban heat profile because pollution generates anthropogenic heat which increases the ambient air temperature. TARU Surat City Profile 21

TARU Leading Edge Email: info@taru.org; Web: www.taru.org 541/2, Sector-8, Gandhinagar 382008, Gujarat, India Phone: +91-79-23240479, 23249882 Fax: +91-79-23248517 424, Qutab Plaza, DLF City Phase I, Gurgaon-122002, Haryana, India Phone: + 91-124-2560424, 2560423 Fax: +91-124-2560421 TARU Surat City Profile 22