CLIMATIC STUDY OF GUWAHATI

CLIMATOLOGYASSIGNMENT

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CLIMATIC STUDY OFGUWAHATI

MADHU SAGARIV SEM – B.ARCH

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1CLIMATIC STUDY OF GUWAHATI

GUWAHATI

• COUNTRY – INDIA• STATE – ASSAM• REGION – LOWER ASSAM• DISTRICT – KAMRUP METROPOLITAN DISTRICT• METROPOLIS AREA – 216 km2 • METRO AREA – 1,528 km2 • ELEVATION – 55.5 m• TIMEZONE – IST (UTC+5.30)• COORDINATES - 26°10′ North latitude

92°49′ East longitude• CLIMATE – CWA (KOPPEN)• Guwahati has a HUMID SUBTROPICAL CLIMATE (Köppen climate classification Cwa – Temperate Dry Winter Hot Summer)•The average annual temperature is 24.2 °C with extremes ranging from 40.6 °C (recorded on April 24, 2014) to 3.0 °C (recorded in January, 1964).

CLIMATEClimatically, whole year can be divided into 4 seasons• WINTER SEASON – December, January, February- Foggy morning, Clear night, Sunny noon- January is coldest- Temperature – 24.6 to 10 degree Celsius• PRE-MONSOON SEASON– March to May- Transition between hot summer and wet monsoon- Temperature increases from March to May- Local rain and thunderstorms are common feature.- Atmosphere is dusty in March.• MONSOON OR SUMMER SEASON– June, July, August and first part of September.- Heavy rainfall and hot summer.- Average rainfall 300 – 400 mm- August is hottest month.- Average temperature is 33 degree Celsius.• RETREATING MONSOON SEASON- Last week of September and first week of October.- Temperature and rains fall down gradually.- Weather is pleasant.

• Guwahati lies in seismic zone 5.

• Zone 5 covers the areas with the highest risks zone that suffers earthquakes of intensity MSK IX or greater.

• The IS code assigns zone factor of 0.36 for Zone 5.

• Structural designers use this factor for earthquake resistant design of structures in Zone 5.• • The zone factor of 0.36 is indicative of effective (zero period) level earthquake in this zone.

• It is referred to as the Very High Damage Risk Zone.

Cwa (KOPPEN CLASSIFICATION)• Temperate, Dry Winter, Hot Summer.• HUMID SUBTROPICAL CLIMATES OR WARM TEMPERATURE They have a warm and wet flow from the tropics that creates warm and moist conditions in the summer months. Summer is often the wettest season. The flow out of the subtropical highs and the summer monsoon creates southern flow from the tropics to that brings warm and moist air to the lower east sides of continents . This flow is often what brings the frequent but short-lived summer thunderstorms so typical of subtropical east-coast climates.

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WIND• November to February – North-East to South-West.• April to mid-September – South-west to North-east.

TEMPERATURE• The maximum temperature ranges from 33 degree Celsius to a minimum of about 10 degree Celsius during the year.• December to February show the low temperature.• August is the hottest month.• October, November are comparatively cooler.

HUMIDITY• Guwahati experiences high relative humidity during the whole year.• The month of January, during the morning, has the highest humidity, above 80%.

RAINFALL• Guwahati receives rainfall mainly from South-west monsoon wind.• Highest rainfall occurs during the month of June, July and August.• Medium rainfall occurs during months of April and May.• During monsoon, Guwahati receives an average rainfall of 365 mm.• The months from November to March are generally dry.• Rainfall is scanty during these months.• The annual rainfall is more than Indian Average.

SUNRISE, SUNSET, DAWN, DUSK TIMES GRAPH

Sun path

Today

June solstice

December solstice

Annual variation

Equinox (March and September)

Sunrise/sunset

Sunrise

Sunset

Time

00-02

03-05

06-08

09-11

12-14

15-17

18-20

21-23

SUN ALTITUDE ANGLE

• 11 am – 77.650

• 12 pm – 76.960

• 1 pm – 65.930

• 2 pm – 52.90

• 3 pm – 39.470

• 4 pm - 260

• Days are longer during May – July.• May-July fall under Monsoon or Summer season.• June Solstice is the longest day in the year.

GUWAHATI, INDIA - SOLAR ENERGY AND SURFACE METEOROLOGYThese data were obtained from the NASA Langley Research Center Atmospheric Science Data Center; New et al. 2002

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MONTH MEAN VALUE OF RELATIVE HUMIDITY (%)

JANUARY 79FEBRUARY 65MARCH 57APRIL 68MAY 75JUNE 81JULY 83AUGUST 82SEPTEMBER 83OCTOBER 82NOVEMBER 82DECEMBER 82ANNUAL 77

RELATIVE HUMIDITY BETWEEN 1971 AND 1990

MONTH MEAN DRY BULB TEMPERATURE (0C)

JANUARY 17.1FEBRUARY 19.0MARCH 22.9APRIL 25.3MAY 26.7JUNE 28.4JULY 28.5AUGUST 28.8SEPTEMBER 27.9OCTOBER 26.0NOVEMBER 22.2DECEMBER 18.1ANNUAL 24.2

MEAN DRY BULB TEMPERATURE BETWEEN 1971 AND 1990

Variable JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Insolation, kWh/m²/day 4.02 4.81 5.48 5.36 5.08 4.40 4.18 4.21 4.06 4.39 4.33 3.93

Clearness, 0 - 1 0.62 0.63 0.60 0.52 0.46 0.39 0.38 0.40 0.43 0.54 0.64 0.64

Temperature, °C 12.01 14.47 18.39 20.29 21.76 23.00 23.19 23.22 22.09 19.70 16.12 13.08

Wind speed, m/s 4.08 3.84 4.02 3.62 3.19 3.07 2.99 2.79 2.74 3.09 3.74 4.03

Precipitation, mm 12 17 55 158 274 358 361 273 197 99 19 8

Wet days, d 1.0 1.4 3.9 8.4 12.0 13.4 14.2 11.5 9.2 4.4 1.3 0.5

MONTH MEAN NO. OF SUNSHINE HOURS

JANUARY 225.5FEBRUARY 213.8MARCH 220.1APRIL 200.6MAY 191.1JUNE 133.1JULY 123.7AUGUST 161.6SEPTEMBER 139.0OCTOBER 205.8NOVEMBER 230.9DECEMBER 231.7ANNUAL 2276.9

MEAN NO. OF SUNSHINE HOURS BETWEEN 1971 AND 1990

PERIOD : 1971 - 2000

Months

MeanTemperature

(oC) MeanTotal

Rainfall(mm)

MeanNumber of Rainy

Days

Mean Number of days with

DailyMinimum

DailyMaximum HAIL Thunde

r FOG SQUALL

Jan 10.6 23.6 11.5 1.2 0.0 0.6 8.5 0.0Feb 12.2 26.0 22.3 2.2 0.0 2.0 1.0 0.1Mar 15.9 29.8 50.9 4.3 0.2 5.2 0.4 0.5Apr 20.0 31.0 159.3 9.2 0.1 12.5 0.0 2.0May 22.5 31.0 256.3 13.3 0.1 14.3 0.1 1.7Jun 24.9 31.9 303.6 14.4 0.0 11.9 0.0 0.3Jul 25.5 31.8 356.8 16.8 0.0 10.9 0.0 0.0

Aug 25.5 32.2 258.6 12.6 0.0 12.5 0.0 0.1Sep 24.5 31.5 194.4 10.5 0.0 9.1 0.0 0.2Oct 22.0 30.3 103.9 4.9 0.0 3.2 2.1 0.0Nov 17.0 27.7 18.4 1.3 0.0 0.9 5.7 0.0Dec 11.9 24.6 7.4 0.6 0.0 0.2 10.9 0.0

Annual 19.4 29.3 1743.4 91.3 0.4 83.2 28.6 4.9

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DATA ANALYSIS

• For designing, considering May, June, July and August becomes critical.• These months experience two extremes of weather i.e., summer and rainy.• Characteristics are heavy rainfall and hot summer.• These months experience high temperatures ranging from 22 to 32 degree Celsius.• These months also experience high rainfall ranging from 255 to 360 mm.• These months have moderate wind speed ranging from 2.7 to 3.2 m/s.• Solar insolation ranges from 4.2 to 5.1 kWh/m2/day.• Cloud cover is around 55% to 62%.• During these months, it rains more than half a month.

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GENERAL OBSERVATIONS

• The revenue villages around Guwahati are mostly dominated by houses for which bamboo reinforced biomass was traditionally used as cladding material while thatch or corrugated iron sheets were used as roofing materials.• The majority of houses in these villages around the city of Guwahati are of traditional Assam-housing typology where the roofing system consists of timber / bamboo trusses supporting thatch or CGI sheets.• The wall system is made of Ikra and / or bamboo-reinforced biomass cladding.• However, a gradual shift towards confined masonry hoouses (i.e., burnt brick masonry walls 6 x 6” RC posts, RC bands at lintel level, roof construction made of timber or tubular steel trusses supporting CGI sheet roofing) can be observed.• The various traditional construction practices and housing types that are prevailing today in the different regions have evolved based on technology transfer one generation to the next by word of mouth or by some kind of documentation done by practicing masons and end users.• The construction schemes have characteristics that address the prevalent local conditions of weather and other environmental and natural hazards i.e., earthquakes, floods or cyclones.

NON‐ENGINEERED CONSTRUCTION TYPOLOGIES

•The variety of non‐engineered construction typologies is quite limited in the city of Guwahati as well as surrounding sub‐urban and rural areas.•In general, these building typologies are constricted to the traditional Assam‐ type house as well as both unreinforced and confined clay brick masonry houses.•The Assam‐type (Ikra) house is a vernacular construction typology made of timber.•Traditionally, it was the most common building type throughout Northeast India which is located in the country’s most severe seismic zone, i.e. Zone V – corresponding to a MSK‐intensity IX (9.0).•The majority of these houses were and still are used for residential purposes while the construction technology has been transferred traditionally from one generation of local masons to the next.•During the colonial era, the British made this type of construction popular by preparing specifications and improving the construction technology.•The advantage of this both lightweight and eco‐friendly construction was well understood by the successive governments before and after India’s independence.•During this period of time, the practice was largely adopted for construction of government offices and residences across the Northeast Indian states.•The Assam Public Works Department (APWD) included specifications of this type of housing in their building schedule.• In rural areas, these houses are typically built with lightweight locally available material like bamboo, wooden planks, thatch etc. and are generally termed as ‘thatch house’.• These housing types have traditional systems of bamboo posts in rural areas and wooden posts in more urban areas.•Bamboo posts are inserted into the ground to act as compression members and are tied with horizontal bamboo/wooden girders with the help of coconut fibre ropes or bamboo ropes to give a proper shape and framing action.•Bamboo or seasoned wood has natural resistance to decay, which makes these houses sustainable and low on maintenance. It was noted that the majority of houses survived the recent big earthquakes in 1897 (Assam earthquake) and 1950 (Assam Tibet earthquake).•Ikra houses are generally single‐storied structures consisting of brick or stone masonry walls up to about 1 m above the plinth.•This masonry supports the walls consisting of bamboo woven together with a wooden frame, and plastered with cement or mud plaster.•Even though this building typology is more prevalent in rural areas, a significant percentage of this type of housing can be also found in the cities of the region.

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7

• Figure 2 – Traditional Assam-type building in an urban residential area.• Figure 4 – Timber truss used in the roofing o Assam-type building built in 1950-1960 by Assam PWD.• Figure 5 – Two-way slope of the roofing system, which provides efficient bracing action at the post plate level against out-of-plane failure.

• Figure 6 – Typical half-wall in bricks above plinth, which interface with the timber frame panels to contain the upper part of the wall made of reed with cement mortar plaster work. The timber posts are bolted to the plinth. These kind of lighter and well-integrated wall systems are now replaced with heavier brick work, which are sometimes not well-integrated and thereby increasing the falling hazards of walls during earthquakes.• Figure 7 – Nowadays traditional Assamese houses coexist along with RC constructions that have become more popular.

CLIMATIC STUDY OF GUWAHATI

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• Guwahati’s building stock is dominated by 3 groups of building typologies traditional Assam-type houses, confined clay brick masonry houses, as well as, ductile and non-ductile RC frame structures.• In the semi-urban and rural areas around the city, the traditional Assam-type houses had been and still are being replaced by confined masonry houses while a wide range of variations (especially with respect to used building materials) can be observed.• However, these houses can also be found in large numbers in urban areas.• The urban and sub-urban housing stock is dominated by reinforced concrete frame buildings (with clay brick masonry infill walls) upto 8 stories high.• There are a few commercial buildings with greater storey numbers.• The observed construction technology and workmanship are considered to be fairly good

CLIMATIC STUDY OF GUWAHATI

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JANUARY FEBRUARY MARCH

12 PM

2 PM

INFORMATION

• WINTER SEASON• COLDEST MONTH• TEMPERATURE – 120 C – 230 C• RAINFALL – 10 – 12mm• CLOUD COVER – 38%• RELATIVE HUMIDITY – 79%• WIND DIRECTION – NE to SW

• WINTER SEASON• TEMPERATURE – 120 C – 260 C• RAINFALL – 17 – 22mm• CLOUD COVER – 63%• RELATIVE HUMIDITY – 35%• WIND DIRECTION – NE to SW

• PRE-MONSOON SEASON• ATMOSPHERE IS DUSTY• TEMPERATURE – 160 C – 300 C• RAINFALL – 50 – 55mm• CLOUD COVER – 40%• RELATIVE HUMIDITY – 57%• WIND DIRECTION – NE to SW

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APRIL MAY JUNE

12 PM

2 PM

INFORMATION

•PRE-MONSOON SEASON• TEMPERATURE – 200 C – 310 C• RAINFALL – 155 – 160mm• CLOUD COVER – 48%• RELATIVE HUMIDITY – 68%• WIND DIRECTION – SW TO NE

•PRE-MONSOON SEASON• TEMPERATURE – 220 C – 310 C• RAINFALL – 250 – 275mm• CLOUD COVER – 54%• RELATIVE HUMIDITY – 75%• WIND DIRECTION – SW to NE

• MONSOON OR SUMMER SEASON• TEMPERATURE – 250 C – 320 C• RAINFALL – 300 – 360mm• HIGH RAINFALL• CLOUD COVER – 61%• RELATIVE HUMIDITY – 81%• WIND DIRECTION – SW to NE

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JULY AUGUST SEPTEMBER

12 PM

2 PM

INFORMATION

•MONSOON OR SUMMER SEASON• TEMPERATURE – 250 C – 320 C• RAINFALL – 355 – 360mm• HIGH RAINFALL• CLOUD COVER – 62%• RELATIVE HUMIDITY – 83%• WIND DIRECTION – SW to NE

•MONSOON OR SUMMER SEASON• HOTTEST MONTH• TEMPERATURE – 260 C – 320 C• RAINFALL – 260 – 275mm• CLOUD COVER – 60%• RELATIVE HUMIDITY – 82%• WIND DIRECTION – SW to NE

• FIRST WEEKS - MONSOON OR SUMMER SEASON• LAST WEEKS – RETREATING MONSOON SEASON• TEMPERATURE – 240 C – 310 C• RAINFALL – 190 – 195mm• CLOUD COVER – 57%• RELATIVE HUMIDITY – 83%• WIND DIRECTION – SW to NE

• Orientation along NW-SE is preferable because the orientation shades two of the sides and provides shadow for long distance.• The longest side along NW-SE.

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OCTOBER NOVEMBER DECEMBER

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2 PM

INFORMATION

• RETREATING MONSOON SEASON• TEMPERATURE – 220 C – 300 C• RAINFALL – 15 – 20mm• CLOUD COVER – 46%• RELATIVE HUMIDITY – 82%• WIND DIRECTION – SW to NE



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1 2 3 4

PERIMETER (2x10) + (2x5) = 30 m (2x10) + (2x5) = 30 m (4 x 7) = 28 m (4 x 7) = 28 m

HEIGHT 3 m 9 m 3 m 9

AREA (S) 30 x 3 = 90 m2 30 x 9 = 270 m2 28 x 3 = 84 m2 28 x 9 = 252 m2

VOLUME (V)

10 x 5 x 3 = 150 m3 10 x 5 x 9 = 450 m3 7 x 7 x 3 = 147 m3 7 x 7 x 9 = 441 m3

S/V 90 / 150 = 0.6 270 / 450 = 0.6 84 / 147 = 0.57 252 / 441 = 0.57

5 6 7 8

PERIMETER (2x3)+(2x10) = 26 m (2x5) + (2x15) = 40 m 4 x 10 = 40 m 4 x 15 = 60 m

HEIGHT 3 m 3 m 3 m 3 m

AREA (S) 26 x 3 = 78 m2 40 x 3 = 120 m2 40 x 3 = 120 m2 60 x 3 = 180 m2

VOLUME (V)

3 x 10 x 3 = 90 m3 5 x 15 x 3 = 225 m3 10 x 10 x 3 = 300 m3 15 x 15 x 3 = 675 m3

S/V 78 / 90 = 0.86 120 / 225 = 0.53 120 / 300 = 0.4 180 / 675 = 0.26

• Case 7 and Case 8 are preferable as the S/V ratio is less.• This helps in reducing the heat gained by the interior of the building.

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5 6 7

PERIMETER (2x7.75)+(2x15.5)=46.5m (2x6.3) + (2x18.9) = 50.4 m 4 x 10 = 40 m

HEIGHT 3 m 3 m 3 m

AREA (S) 7.75x15.5=120 m2 6.3 x 18.9 = 119 m2 40 x 3 = 120 m2

VOLUME (V)

7.75 x 15.5 x 3 = 360.4 m3 6.3 x 18.9 x 3 = 357.2 m3 10 x 10 x 3 = 300 m3

S/V 120 / 360.4 = 0.33 119 / 357.2 = 0.33 120 / 300 = 0.4

CLIMATIC STUDY OF GUWAHATI

Design

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