MAPPING A HUMAN MAPPING A HUMAN DISCOMFORT INDEX OVER DISCOMFORT INDEX OVER

SOUTH AFRICA SOUTH AFRICA What Does the Future hold What Does the Future hold

Compared with the Present?Compared with the Present?Compared with the Present?Compared with the Present?

Roland Schulze & Nicholas DavisRoland Schulze & Nicholas Davis

Centre for Water Resources Research

University of KwaZulu-Natal

Pietermaritzburg, South Africa

Human Comfort / DiscomfortHuman Comfort / Discomfort1. The concept of human comfort is based on criteri a of the energy balance between human body and its environment

0 = M ± R ± Cv ± Cd − Ewhere

M is the metabolic heat, R the heat exchange by radiation,Cv the heat exchange by convection, Cv the heat exchange by convection, Cd the heat exchange by conduction and E the heat losses by evaporation.

2. Human body thermal balance consists of maintaini ng the body’s temperature between 36.5 °C and 37°C, with increases or decreases in the body’s temperature producing discomfort

3. If the body’s temperature > 40 °C blood circulation problems appear, and > 41–42 °C coma or total collapse can occur

HumanHuman Discomfort Indices …1Discomfort Indices …1The three most significant climatic variables for comfort are:

1. Humidity , which controls evaporation and plays an important role at high temperatures where perspiration is the cooling mechanismperspiration is the cooling mechanism

2. Wind , which speeds up evaporation by convection

3. Temperature , as the main heat gain source, as a surrogate of solar radiation

Human Discomfort Indices …2Human Discomfort Indices …2

In the present work we use Thom’s (1959) Human

Many Human Discomfort Indices have been developed over the years, e.g.Siple and Passel (1945); Brooks (1950); Buettner (1954); The American Society of Heating and Air Conditioning Engineers (1955); Tanenbaum and Sohar (1960); Olgyay (1963) Landsberg (1964); Terjung (1966); Jaureguiand Soto (1967); Watson and Labs (1983), Vinje’s index (1993)

In the present work we use Thom’s (1959) Human Discomfort Index, TDI … a formulation using a combination of air temperature, T (°C) and relative humidity, RH:

TDI (°C) = T − 0.55 ∗∗∗∗ (1 − 0.01 ∗∗∗∗ RH) ∗∗∗∗ (T − 14.5)

Required for this are temporal & spatial databases of daily maximum & minimum temperatures and RH

Requirement 1 Requirement 1 Databases of Databases of Daily Daily

Maximum / Minimum Maximum / Minimum Temperatures and Relative Temperatures and Relative Temperatures and Relative Temperatures and Relative Humidity Over South Africa Humidity Over South Africa

at Timeat Time --Steps & Local Steps & Local Resolutions that MatterResolutions that Matter

Development of a Daily Development of a Daily Temperature Temperature Database for SADatabase for SA

1. Methodology1. Methodology

Schulze & Maharaj, 2004

Examples of Derivatives from the Daily Examples of Derivatives from the Daily Temperature DatabaseTemperature Database

Schulze, 2008

Verification: July

y = 0.8957x + 0.0206R2 = 0.84

0.0

0.5

1.0

1.5

2.0

2.5

Est

imat

ed

Vap

our

P

ress

ure

(kP

a)

Verification: January

y = 1.0384x - 0.0679R2 = 0.83

0.0

0.5

1.0

1.5

2.0

2.5

0.0 0.5 1.0 1.5 2.0 2.5Observed Vapour Pressure (kPa)

Est

imat

ed V

aapo

ur

Pre

ssur

e (k

Pa)

ea (Pa) = 610.78 x 10(17.269 Ta / (237.3 + Ta)

e (P ) = f (latitude, longitude, distance from

RH (%) = Actual vapour pressure X 100Saturated vapour Pressure

= ed /ea. 100

Determination of Daily Determination of Daily Maximum & Minimum Maximum & Minimum

Relative Humidity over SARelative Humidity over SA

0.0

0.0 0.5 1.0 1.5 2.0 2.5Observed Vapour Pressure (kPa)

ed (Pa) = f (latitude, longitude, distance from sea, altitude, daily temperature range)(Schulze and Chapman, 2008)

Requirement 2 Requirement 2 Spatial Databases at Spatial Databases at

Local Resolutions that Local Resolutions that Local Resolutions that Local Resolutions that MatterMatter

Spatial Database to Model Fluxes & Spatial Database to Model Fluxes & Flows at the Local Scales that MatterFlows at the Local Scales that Matter

5 838 Relatively Homogeneous 5 838 Relatively Homogeneous (Interlinked) (Interlinked) QuinariesQuinaries

QnCDBQnCDB: Each with a 50 Year : Each with a 50 Year Record of DAILY Rainfall, Record of DAILY Rainfall,

Schulze & Horan, 2010 Schulze et al., 2010

FLOWPATH CONFIGURATION WHEN MODELLING ATQUINARY CATCHMENT SCALE

QC V11A

V11A 1 V11A 2 V11A 3

QC V11C

V11C 1 V11C 2 V11C 3

QC V11D

V11D 1 V11D 2 V11D 3

Flowpath

Quaternary Catchment Outlet

External Quaternary Catchment

Internal Quaternary Catchment

Procedure: Jenks’ Optimisation using Procedure: Jenks’ Optimisation using Natural Breaks in AltitudeNatural Breaks in Altitude

Record of DAILY Rainfall, Record of DAILY Rainfall, TTmaxmax, , TTminmin , , RHRHmaxmax, , RHRHminmin , , RRss, , EEpp--mm; Plus Soils and Land ; Plus Soils and Land Cover Attributes & DAILY Cover Attributes & DAILY

RunoffRunoff

Results 1Results 1The Human Discomfort The Human Discomfort

Index Under Present Index Under Present Climatic ConditionsClimatic ConditionsClimatic ConditionsClimatic Conditions

The MidThe Mid --Day (Day (TTmaxmax , , RHRHminmin ) Mid) Mid--Summer Summer (January) Discomfort Situation (January) Discomfort Situation

Classes of Comfort / Discomfort by Classes of Comfort / Discomfort by ThomsThoms’ Human ’ Human Discomfort Index: January MidDiscomfort Index: January Mid --day day Discomfort Index: January MidDiscomfort Index: January Mid --day day

Results 2 Results 2 The Human Discomfort The Human Discomfort Index Under Projected Index Under Projected

Future Climatic Future Climatic Future Climatic Future Climatic ConditionsConditions

The MidThe Mid --Day (Day (TTmaxmax , , RHRHminmin ) Mid) Mid--Summer Summer (January) Discomfort Situation (January) Discomfort Situation

Downscaling: GCM Downscaling: GCM -- LocalLocal

Forcing: Emission Scenarios Forcing: Emission Scenarios

Initial ConditionsInitial Conditions

Global Climate Global Climate

Models (GCMs)Models (GCMs)

(e.g. HadCM3, (e.g. HadCM3,

ECHAM5, ~200 km)ECHAM5, ~200 km) Regional Climate Regional Climate Models (RCMs) or Models (RCMs) or

statistical downscalingstatistical downscaling

(~25 km)(~25 km)

Impact Impact

ModelsModels

(~5 km)(~5 km)

Hewitson, 2010Hewitson, 2010

GCMsGCMsCGCM3/T47(no DF) (CA)CNRM - CM3 (FR)ECHMA5/MPI - OM (DE)GISS - ER (US)

QUICKFLOW

INTERCEPTION

PRECIPITATION

TOPSOIL

SURFACE LAYER

Downscaling by CSAG to Downscaling by CSAG to > 2 600 rainfall stations> 2 600 rainfall stations

Downscaling to > 400Downscaling to > 400temperature stationstemperature stations

•• Final selectionFinal selection•• Assignment to Assignment to QnCQnC•• Precipitation adjustmentPrecipitation adjustment•• 5 838 x 3 x 5 files of daily P5 838 x 3 x 5 files of daily P

•• Final selectionFinal selection•• Assignment to QnCAssignment to QnC•• Lapse rate adjustmentLapse rate adjustment•• 5 838 x 3 x 5 files of daily5 838 x 3 x 5 files of daily

TTmxdmxd , T, Tmndmnd , R, RSS, E, EPP--MM

METHODOLOGYMETHODOLOGY

GISS - ER (US)IPSL - CM4 (FR)

Present 1971 - 90Intermediate 2046 - 65Distant Future 2081 - 00

RUNOFF

GROUNDWATER STORE

INTERMEDIATE STORE

SUBSOIL

TOPSOIL

QC V11A

V11A 1 V11A 2 V11A 3

QC V11C

V11C 1 V11C 2 V11C 3

QC V11D

V11D 1 V11D 2 V11D 3

. . .

Assigning Homogeneous Assigning Homogeneous Response ZonesResponse Zones

5 838 Interlinked 5 838 Interlinked QuinariesQuinaries

SoilsSoilsLand CoverLand Cover

Climate FilesClimate Files

Lumsden et al., 2010 Schulze et al., 2011

GCMsGCMsCGCM3/T47(no DF) (CA)CNRM - CM3 (FR)ECHMA5/MPI - OM (DE)GISS - ER (US)IPSL - CM4 (FR)

CHANGE CHANGE ANALYSESANALYSES

Temperature Temperature Related Related AnalysesAnalyses

Rainfall Rainfall Related Related AnalysesAnalyses

Hydrological / Hydrological / HydroHydro--EcolEcol AnalysesAnalyses AgriculturalAgricultural

AnalysesAnalyses

Annual Temperature StatisticsMonthly Temperature StatisticsFrost DaysCold SpellsHeat WavesClimate ZonesValidation Studies Human Discomfort Index

Annual Rainfall StatisticsMonthly Rainfall StatisticsSeasonality and ConcentrationThreshold Rainfalls ExceededShifts in Timing of Rains > ThresholdsShort and Long Duration Design PMeteorological Droughts (S, M, M, / A, M)Validation Studies

IPSL - CM4 (FR)

Present 1971 - 90Intermediate 2046 - 65Distant Future 2081 - 00

AnalysesAnalysesAnnual Runoff/Streamflow StatsCardinal Month StatsThresholds of Streamflows Exceeded Potential EvaporationSoil MoisturePeak Discharge; Sediment YieldHydrological Droughts (Sev, Mod, Mld, / An, Mo)Shifts in Timing of Streamflows > Thresholds1 - 7 Day Design Stormflows (2, 5, 10, 20, 50, 100 yr RP)Env Flows: Indicators of Hydrological AlterationEnvironmental Flows: Water TemperatureEstuarine ResponsesLand Use / CC Dynamics: Mgeni CatchmentCase Studies: Durban; Cape Town; Waterberg,

Blyde, Olifants-Doorn, Berg Socio -Economic Studies: Berg, Mgeni

2nd Order Analyses- Heat Units - Chill Units

3rd Order Analyses- Pests /Diseases (Ch/CM/El/Ea/SbR/OF)- Crops (Mz, Wh, So, Sb Sc)- Pastures (Ec, Kik)- Crops - Horticulture- Production Forestry (Am, Eg, Pp)- Primary Production- Irrigation Requirements

Vegetation Dynamics re Climate Ch Case Studies: Blyde, Olifants-Doorn

Schulze, 2011; 2012

How do How do Outputs Outputs

from from Different Different

GCMs GCMs Compare Compare

in the in the Control Control Period? Period?

19711971--19901990

Category: Too hot Category: Too hot and humid, and humid,

midmid --day Januaryday January

Projected Projected IncreasesIncreases into into the Future in Days in the Future in Days in

January which are January which are too Hot / Humid for too Hot / Humid for

Human ComfortHuman Comfort1971 - 1990

2046 - 2065

2081 - 2100

GCM: ECHAM5/MPI-OM

How do How do Projected Projected Outputs Outputs

from from Different Different

GCMs GCMs Compare Compare into the into the into the into the Future? Future?

2046 2046 -- 20652065

Projected Projected DecreasesDecreases into into the Future in Days in the Future in Days in

January which are January which are Partially ComfortablePartially Comfortable

1971 - 1990

GCM: ECHAM5/MPI-OM

2046 - 2065

2081 - 2100

Concluding ThoughtsConcluding Thoughts1. GCMs give consistent results on increases in

mid -summer human discomfort 2. Many sectors could be affected by this, e.g.

Tourism industry Building design City planning Construction industry Construction industry Agricultural workers Medical aid Sporting codes

3. Further work could be extended to Cold discomfort indices Livestock heat stress indices ….