aWhere Case Study: South Africa & the Impacts of Weather Variability

aWhere Case Study: South Africa & the Impacts of Weather Variability

Weather Insights:

South Africa is considered a water-scarce country, and the 30th driest country in the world. South Africa has experienced water shortages since 2015, when delayed rainfalls and decreasing dam levels led to a drought declaration. It was the worst drought in the country since 1982. In 2018, Cape Town experienced a massive water crisis and neared a ‘day zero’ where the area almost ran completely out of water (Time). This was attributed to years of drought coupled with water management issues. Since then, heavy restrictions have been put in place but this region is prone to water availability issues due to drought and rainfall variability which will only increase this risk.  

An additional hazard that threatens water supplies is agriculture while another climate hazard for public health are heatwaves. Heatwave-related deaths are often under reported and exposure and vulnerability to extreme weather is often much higher in sub-Saharan Africa. “Climate scientists have long forecast that a clear sign of global warming would be seen with a change in heatwaves,” says Dr. Perkins Kirkpatrick.  Heatwaves coupled with drought conditions have severe implications for food security. Officials and planners need a better understanding of when these heatwaves and droughts may occur in order to adapt and mitigate the impacts on food security and human health. aWhere’s observed, historical data can help reveal rainfall and heat patterns. The map below illustrates the rainfall conditions this year compared to normal for the month of January.  It was wetter than normal in the Western Cape and drier in Limpopo. This same analysis can be replicated for historical data to lend insight into impending conditions.

Variability of rainfall across South Africa July 2019-July 2020

The South African government recently ended the country’s state of disaster for drought which was met with criticism from farmers and pastoralists as they struggle to adapt to weather variability. The charts here illustrate the variability over the past year. These charts show the weekly precipitation (blue bars) compared to the long-term normal (2006-2019) (orange line) as well as maximum temperature. These charts show how variable the rainfall has been over the past year. Out of season rains, drier conditions, and overall deviations from normal in these locations are shown. Periods that are drier than normal are circled in red, wetter than normal are circled in blue.   Charts like these can be created for any location across the agricultural earth.

As these weekly rainfall charts show, the variability of the rains is the dominant factor.   The timing – when and how much.  This works against agriculture as farmers invest to fit the expected environmental conditions.  Extreme events – too much rain in a short time or too little over an extended time make the economics of farming untenable. 

Trends: Precipitation and Temperature

Changes in weather patterns and impact on crops and food security can be assessed by looking at the past 15 years, today, and 15 days into the future. aWhere uses measures for variability such as coefficient of variation to statistically understand the trends for specific latitudes/longitudes. For the location below, the coefficient of variation (CV) for precipitation is 35% and precipitation over potential evapotranspiration (P/PET) is 38%. CV is a measure of variability and anything above 20% is considered highly variable, at 35-38%, these charts show how variable the rainfall has been in this location in KwaZulu-Natal for the period of January-February from 2006-2019. Weather variability makes it difficult for farmers to plan farm operations because it is difficult to predict how the weather will behave. This also poses challenges for continued planning around drought potential. The map below also illustrates areas that were drier than normal in the month of January 2020. The eastern regions were particularly dry.

These trends over 15 years raise great concern: Precipitation over potential evapotranspiration (P/PET) drops below 1.0 for a 2 month period. This alters the ecological balance from positive water to negative. 

As these trends show, the dry is become drier.  What is critical is the switch of precipitation over potential evapotranspiration (P/PET) from above 1.0 to below – and below 0.75.  This translates as a change from a water surplus to significant water debt and completely different vegetation suites will emerge.  This change in ecology has tremendous impact on farming.  Not only will farmers need to change crops but also agronomics and likely invest in irrigation assuming there is any water to be found.

Implications and Recommendations:

As erratic climate events become the norm, early warning systems must be strengthened to sufficiently warn communities of impending drought and heatwaves. aWhere’s daily-updated data provides the historical observed data needed to make data-driven decisions as well as the current conditions to provide relevant information to farmers and officials on how weather is impacting crop production and water supply. 

With accurate weather data, South Africa can build resilience to weather variability and adapt to climate change. aWhere’s weather data and models help agriculture and input providers, farmers and government agencies in South Africa  and around the world adapt to weather variability and deliver economic resilience to climate change. Other sectors impacted by climate change such as  energy, health, trade (domestic and international) and infrastructure also benefit from aWhere’s weather data and analytical tools to generate actionable insights.