Climate Change Research at WRC

B M PetjaWater Research Commission

19 April 2016

DHI-SA 2016 CONFERENCECOPING WITH DROUGHT: ADAPTATIONS TO WATER STRESS IN THE FACE OF CLIMATE CHANGE

Babatunde Abiodun (UCT), Joel Botai (SAWS), Mathieu Rouault (UCT) & Hannes Rautenbach (SAWS)

Outline

• WRC Key Strategic Areas

• Regionally Extensive Droughts

• Soil moisture-climate interactions under climate change

• The role of ocean in southern Africa climate

• Future climate change impacts on floods and drought hazards.

• Practical implications

• Conclusions

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Key Strategic Areas Water Resource Management

Water-Linked Ecosystems

Water Use and Waste Water Management

Water Utilisation in Agriculture

Cross-cutting Flagship ProgrammeCLIMATE CHANGE

LIGHTHOUSE

KSAs / Research areas

•Water Resource Assessment and Planning

•Water Quality Management

•Water Resource Protection

•Water Resources and Climate

•Water Resource Institutional Arrangements

1.Water Resource Management

• Ecosystem Processes

• Ecosystem Management

• Ecosystem Rehabilitation

• Sustainable Ecosystems Utilization

• Ecosystems & Global change

2. Water-Linked Ecosystems

•Water Services – Institutional and Management Issues

•Water Supply and Treatment Technology

•Sustainable Municipal Wastewater and Sanitation

•Sustainable and Integrated Industrial Water Management

•Mine Water Treatment and Management

•WaterSmart Fund

3. Water Use and Waste management

•Water Utilisation for Food and Fibre Production

•Water Utilisation for Fuelwood and Timber Production

•Water Utilisation for Poverty Reduction and Wealth Creation in Agriculture

•Water Resource Protection and Reclamation in Agriculture

4. Water Utilisation in Agriculture

Climate Change and Regionally-Extensive Droughts in Southern Africa

Babatunde J. Abiodun and Team

Department of Environmental and Geographical Science

University of Cape Town

WRC Project: K5/2317

This project aims to study the characteristics of regionally-extensive droughts (REDs) over Southern Africa and to investigate the regional and global atmospheric features that produce the REDs.

The original objectives were to: 1) incorporate evapotranspiration (ET) into drought indices to obtain a better characterisation of agricultural and hydrological droughts over Southern Africa; 2) understand the mechanisms by which remote and local forcing of drought are translated into surface moisture deficits (P-ET); 3) evaluate climate model’s abilities to represent regionally extensive droughts and the associated mechanisms; 4) understand the potential impacts of climate change on regionally-extensive droughts in Southern Africa.

Drought patterns over Southern Africa

These are the 12 major types (or patterns) of regionally extensive droughts in southern Africa.The colours show the values of a drought index (Standardized Evapotranspiration Index). The index is calculated from surface water balance (rainfall minus potential evapotranspiration). Hence, it account for the influence of global warming. A negative value indicates a dry condition (drought), while a positive indicates a wet condition.

The four drought patterns at the edges show the extremes cases of drought patterns:Top-left => The entire region is experiencing droughtBottom-right => The entire region is experiencing a wet conditionTop-right => The northern half is experiencing a wet condition, while the southern half is experiencing drought.Bottom-left => The northern half is experiencing drought, while the southern half is experiencing a wet condition.

Seasonal variation of the drought patterns

The seasonal distribution of the drought patterns shows that each drought pattern can occur any in season (except that drought number 5 does not occur in DJF).

Transition and Persistence of the Drought Patterns

• This is the seasonal transition of the drought patterns from year to year (1950 - 2014).

• The colours indicate the average SPEI over Southern Africa. The number in each colour shows drought tag number.

• The figure shows that while some drought patterns easily transit to other drought patterns, others can persist and linger for more than two seasons.

Decadal variation of the drought patterns

• The figure shows that the drought pattern in the bottom-right edge (wet condition over the entire region) has not occurred since the last three decades.

• In general, there has been a shift from wet condition to drying condition… • This may be due to climate change.

Soil moisture-Climate Interactions under Climate Change: Implications for Droughts, Heat Waves and Desertification over

Southern Africa

Team:1. Joel O. Botai (Project Leader)2. Mr Thabo Makgoale (Member)3. Christina Botai (Member)

Objectives

Identify CMIP5 simulated hotspots of soil moisture-climate

interactions in the historical runs

Investigate future changes in soil moisture regimes and the

possible impacts on the locations of the hotspots

Investigate the contribution of changes in soil moisture to the

accelerated warming rates over southwestern Africa (Northern

Cape, Namibia and Botswana)

WRC Project: K5/2309

Hot spots of Soil moisture-climate interactions in the

historical runsInteraction hotspots of Soil Moisture- Temperature (SM-T) and Soil

Moisture-Precipitation (SM-P) using the Phase 5 of the Coupled

Model Inter-comparison Project (CMIP5) data sets

A proxy parameter called the coupling index is used to identify

SM-T, SM-P hotspots is the diagnostic relationship i.e., Spearman’s

and lagged correlations and regression between SM-P/T

Results

Simulations from all the models considered in the analysis

(i.e., CanESM2, GFDL-ESM2M and CNRM-CM5)

demonstrated that the SM-T exhibits negative

correlations in central parts of southern Africa during DJF

season

Northern and central parts of the southern African show

strong positive SM-P correlations with visible marked

transition zones. These zones suggest that there exists

possible hotspots, particularly towards the Namibia-

Botswana border. The presence of the hotspots in this

region could be attributed to the presence of wet-dry

climatic transition zones

weak transition zones reminiscent of soil hotspots over

some parts of the western southern Africa corresponding

to the three main climatic zones characteristic of

southern Africa i.e., wet (in the eastern region), semi-arid

(central southern Africa) and arid in the western parts of

southern Africa

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Historical soil moisture and temperature correlation across HadGEM-CC (row 1), CanESM (row 2), GFDL-ESM2M (row 3) and CRNM-CM5 (row 4) models for DJF (col 1), MAM (col 2) and SON (col 3).

Future changes in soil moisture regimes

A methodology reported in MingXing and ZhuGuo

(2012) is used to demarcate dry-wet climatic zones

the SM anomalies are used to divide the dry-wet

climate zones in order to reveal the inherent features of

the boundary dynamics and the resulting changes of

the climate zones.

Use future changes in SM and therefore tracking

possible shifts on the locations of transition zones over

southern Africa.

Use the spatial correlations of means and linear trends

in SM as proxy-parameter for tracking spatial shifts in SM

transition zones

Results

The historical simulations of the CNRM-CM5

model show negative linear trend in SM

during DJF while the future simulated SM

trends are positive. This change in the SM

trend illustrates a possible shift in the location

of SM-climate coupling strengths.

From the historical and future simulations using

CanESM2 model, correlations between SM

and P during MAM increase from historical to

the future, with the dry regimes showing high

correlations and wet regimes showing weak

correlations

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Soil moisture trends; first and second columns from the

left corresponds to soil moisture trends derived from

historical simulations; third and fourth column from the

left correspond to soil moisture trends derived from

future simulations. The following models were used:

HadGEM (first row from the top), CanESM (second

row) and CRNM (third row).

Contribution of soil moisture to the acceleratedwarming rates over southwestern Africa

In order to investigate the impacts of SM on accelerated

warming, the link between changes in SM and higher warming

rates projected over southwestern Africa is assessed

In this regard, the correlation of SM and extreme temperatures

over the study region is determined

The extreme value analysis is considered where temperature is

used with SM acting as a covariate. In this regard, the likelihood-

ratio test is used to assess whether the inclusion of the covariate

impacted on the model fit

Results

the annual temperature extreme seem to follow an

extreme value distribution in most of the selected

study region. In particular, areas exhibiting a

significant covariate (i.e., the SM in the GEV model)

significantly improve the estimation of annual

maximum temperature extremes.

In addition, areas where SM is significant covariate

there exists a negative relationship between the SM

and temperature extremes. Thus, results suggest that

areas with higher SM levels are correlated to lower

temperature extremes, while areas with lower SM

levels are associated with higher temperature

extremes.

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Impacts of SM on temperature extremes asquantified by the profile log-likelihood ofmaximum likelihood diagnostic parameter forthe GEV. The distribution of areas where SMinfluences extreme temperature based non-stationary GEV model of extreme temperature.

ROLE OF THE OCEAN ON SOUTHERN AFRICAN CLIMATE Mathieu Rouault and Team

1 Department of Oceanography, MARE Institute, University of Cape Town.2 Nansen-Tutu Center for Marine Environmental Research, University of Cape Town.

AIMS

1. To provide an improved conceptual understanding of ocean-atmospherelinkages to hydroclimatic variability in Southern Africa at relevant spatialand temporal scales with a focus on floods and droughts.

2. To better characterize the role of El Nino on droughts and of La Nina onfloods in Southern Africa.

3. To understand the role of adjacent oceans in moisture transport, rainfall,and extreme weather and climate of South Africa

4. To understand the non linearity between Southern African rainfall andENSO

5. To understand the role of the ocean on decadal variability of SouthernAfrican Climate

WRC Project: K5/2425

Average sea surface temperature anomaly from the mean condition duringmature phase of EL NINO in austral summer. Orange is warmer than normalblue is colder than normal

Global average rainfall standardized anomaly during mature phase of EL NINOin austral summer. Blue/green is wetter than normal, yellow/red is dryer thannormal. -1(red) is one standard deviation below normal here.

Summer (DJF) rainfall anomaly from the mean for south Africa from summer 1921/1922 to 2007/2008. El Nino year in red, La Nina in blue. -1 is one standard deviation below normal

1.Most, but not all, severe droughts in South Africa are associated with El Nino (red bars)

2.La Nina is better associated with wetter year (blue bars)

3.No relationship between strength of El Nino and intensity and spatial extension of drought (Weak El Nino can lead to strong droughts, Strong el Nino sometimes not associate with drought at all (1997,1998)

Precipitation anomaly for each month of 2014/2015 summer (Belinda Monyela Honour’s Dissertation 2015, WRC Project K5/2425 Ocean Impact on Southern Africa Climate Variability and Water Resources)

Drought (2014/2015)

• El Nino lead to severe drought 50 % of the time

• Correlation with El Nino start in December (December to March)

• Most severe drought at the 1 year scale involved El Nino

• All drought at the 2 years scale involved El Nino

• Coupled model used by IPCC do not simulate the El Nino impact well.

• Other mode of climate variability are either triggered by El Nino and/or do not have an impact on Summer rainfall. No relation between sunspot and drought. Other mode of variability are a symptom rather than a driver.

• Decadal variability of climate linked to decadal variability of the Pacific (10 year cycle, 20 year cycle) with similar mechanisms.

• 2014/2015 was the strongest drought since 1995 and was triggered by a small El Nino

• 2015/2016 was one the strongest drought on record and was triggered by a strong El Nino

Summary

Future climate change impacts on floods and

drought hazards in South Africa for planning and

decision making Hannes Rautenbach and TeamSouth African Weather Service

WRC Project: K5/2247

Objective:

To use various ensemble groups of AMIP5 GCMs, CORDEX RCMs, statistical downscaling and hydrological model

(ACRU) results to generate climate change projections of extreme rainfall (droughts and floods) in South Africa.

Preliminary findings:

o All model ensembles used exhibited skill in regenerating the observed spatial patterns of extreme rainfall categories (Q2 and Q4), although systematic errors exist in the simulated magnitude of values.

o The majority of model outcomes point towards a future increase in the frequency of low rainfall drier periods as well as an increase in extreme flood events, without a major shift in the annual rainfall median.

o Results put emphasis on the outlook that although significant shifts in the annual mean rainfall might not pose significant risks to the water sector, the increase of extreme dry and wet frequencies might pose challenges to shorter term planning and disaster management.

RCP 8.5: Annual temperature change (ºC) relative to 1985-2005 RCP 8.5: Annual rainfall change (mm/month)

relative to 1985-2005

RCP 4.5: Annual temperature change (ºC) relative to 1985-2005 RCP 4.5: Annual rainfall change (mm/month) relative to 1985-2005

SAWS WRC project: Projected change of the MEDIAN

2046 – 2065 (+50 years) 2076 – 2095 (+80 years) 2046 – 2065 (+50 years) 2076 – 2095 (+80 years)

2046 – 2065 (+50 years) 2076 – 2095 (+80 years) 2046 – 2065 (+50 years) 2076 – 2095 (+80 years)

RCP8.5 projected change in rain day decile categories for the Vaal River catchment area. The number of events in the lower 10% category might increase with 22%, while 0.43% of events might exceed a daily rainfall value ever

appeared in history. Results were obtained from historical (1986 to 2005) and projected (2041 to 2060) simulations by

an ensemble of six AMIP5 GCMs.

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Some Practical Implications …

Petja et al 2004

Conclusion

• Climate change is a reality and it need to be incorporated as part of business as usual.

• Despite the fact that our country is naturally water scarce, there is an increase in the frequency of droughts.

• Observed trends confirm the projected changes.

• More action is required at local scale in terms of adaptive response and mainstreaming.

• United sectoral and inter-sectoral response will defeat the might of climate change.

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Current Climate Change Projects

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K5/ Title Organisation Contract term

2247 Future climate change impacts on flood and drought hazards in South Africa for planning and decision-making

SAWS 1/4/2013 - 31/7/2016

2309 Soil Moisture-Climate Interactions under Climate Change: Implications for Droughts, Heat Waves and Desertification over Southern Africa

SAWS 1/4/2014 - 31/3/2017

2430 Optimising the use of updated and additional products from the Nowcasting Satellite Application Facility to improve the Rapidly Developing Thunderstorms and Convective Rainfall Rate products

SAWS 1/04/2015-31/03/2017

2249 Managing limits in skill for seasonal climate forecasting UCT 1/4/2013 - 31/5/2017

2325 Quantification of uncertainty in weather and climate prediction and its effective communication for better decision making.

CSIR 1/4/2014 - 31/3/2017

2317 Regionally-extensive droughts and climate change in Southern Africa: mechanisms, model reliability and projections

UCT 1/4/2014 - 31/3/2017

2425 Ocean impact on southern African climate variability and water resources

UCT 1/04/2015-31/03/2018

2457 Predictability of hydroclimatic variability over eastern South Africa under climate change.

CSIR 1/04/2015-31/03/2018

2267 Building resilient landscapes by linking social networks andsocial capital to ecological infrastructure 01/04/2013-30/09/2015

2266Upscaling understanding of water movement, land degradation and carbon cycle in support of effective payment for ecosystem services UKZN 01/04/2013-01/04/2018

2354

Demonstration of how healthy ecological infrastructure can be utilized to secure water for the benefit of society and the green economy through a programmatic research on selected landscapes UKZN 01/04/2014-01/04/2020

2349Green water innovations for sustainable aquatic ecosystems and socio-economic development AFRICEEGE 01/04/2014-31/03/2016

2265 A climate change risk assessment of water hyacinthbiological control WITS 01/04/2013-30/09/2016

2336A multi-proxy investigation into past and present environmental change at Lake St Lucia WITS 01/04/2014-31/03/2017

2337Assessing the effect of global climate change on indigenous and alien fish in the Cape Floristic FRC 01/04/2014-31/10/2017

2348 Ecosystem process and function of temporary wetlands:baseline data for climate change predictions NMMU 01/04/2014-31/03/2017

2459Development of a predictive management tool for Orange River blackfly outbreaks FRC 01/04/2015-30/06/2017

2466

Long term WRF-chem modelling and verification of wet and dry acid deposition over South Africa and investigation of impact of power generation stack emission limits on acid deposition Escience 01/04/2015-31/03/2017

Title Organization

The development of a Bayesian model of the ecosystem and mouth dynamics for Temporary Open/Closed Estuaries (TOCEs).

Univ of Zululand

Assessment of carbon storage in wetlands EON

Establishing remote sensing toolkits for monitoring freshwater ecosystems under global change CSIR

Atmospheric deposition impact assessment Escience

An integrated early warning forecast system for wet seasons and their relation to flooding events: A predictability study in suport of hydrological applications CSIR

Impact of the predictability of continental tropical lows on hydrological modelling: current state and future projections UP

Integrated land use and water use in Water Management Areas, with a view on future climate and land use changes CSIR

Underway

Hydro-meteorological forecasting and

drought early warning detection for

municipal and agricultural water use at

a catchment scale

Started April 2016

Thank You

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