Zimbabwe and the bulk of the SADC region are expected to have normal-to-above normal rainfall in the 2021-2022 cropping season. In this report, Agric, Environment & Innovations Editor Sifelani Tsiko (ST) speaks to Benjamin Kwenda (BK), an agriculture meteorologist at the Meteorological Services Department about the seasonal forecast and possible implications of a wetter season.
ST: Normal to above-normal rainfall has been forecast for both the first and second rainfall seasons for Zimbabwe and most parts of the SADC region. Can you briefly tell us what phenomenon is behind the prospects for the good rains?
BK: There are two main reasons why we are having good rains this season. The first one is El Nino-Southern Oscillation (ENSO). Currently, there is a forecast of La Nina conditions which are actually developing within the ocean. This has generally brought more rains or good rains over the country.
Each time when we have La Nina conditions, we usually have good rains. So these conditions are expected to develop into what we call a weak La Nina in the period around December and then from around January going forwards we are expecting neutral conditions to persist.
This is why we are expecting good rains. And also, we have what we call the Indian Ocean Dipole. The Indian Ocean Dipole (IOD) occurs within the central or equatorial parts of the Indian Ocean. As we have a negative IOD, as we are currently expecting, it influences rainfall patterns or wetter conditions especially in southern Africa which also includes Zimbabwe. This is the phenomenon influencing the good rains we are expecting.
ST: Normal to below normal rainfall is likely in some parts of the SADC region. Zimbabwe is forecast to receive above average rains for most of the 2021-2022 season. Does this mean that there are no areas which are likely to experience some drought or below average rains in Zimbabwe?
BK: We will still have pockets where there will be normal to below-normal rains. We can’t rule out the possibility that some pockets will experience some droughts. At the moment we are not able to say which parts will receive below normal rains compared to the other.
For the normal or above normal class, we are simply talking about the average for that specific area — for example it does not mean that Chimanimani or Nyanga will receive similar amounts of rain with say Beitbridge or Mbire. Why?
It’s because each area has its own normal. Some places their normal are not anywhere above 500mm while for some places their normal range is between a 1 000mm to 1 500mm. These differences need to be factored in.
ST: Last year, climate experts from Zimbabwe and the SADC region largely scored major hits in their prediction of the just ended season. Can you tell us what was the level of the score or hits for Zimbabwe?
BK: The level of score or hits for Zimbabwe was actually high. We had high hits and I think the only part that we had a miss was in Matabeleland North where we forecast normal to below normal rains when in actual effect the region got normal-to-above normal rains. Throughout the other parts of the country we had gone for normal-to-above normal rainfall. This was the score we had.
ST: The COVID-19 pandemic has disrupted several sectors and meteorology is no exception. The quality and quantity of the observational data that feed into weather forecasting models has been affected by the pandemic. To what extent has this affected your forecasting models for the 2021-2022 cropping season?
BK: With regards to the Covid-19 pandemic, it has affected the way the data has been flowing back to us. When we are drawing up our forecasting, we use referencing periods. For this period, we are still using the period from 1981 up to 2010. Anything after 2010 or up to 2021 is what we use for our verification models.
So we cannot say that the data that we received affected our models, but it affected the verification of what transpired last season. We have stations which are manned by our own personnel and these have actually been giving us data consistently. But we had problems with volunteer stations. We had breaks in communication, but we are still working to manage the situation.
ST: Weather forecasting in Zimbabwe and the entire SADC region still faces constraints. What are some of the challenges and how are you addressing them to ensure you gather reliable data and make better observations?
BK: One of the challenges that we still have is that we still have gaps especially in terms of our observation network and in terms of the equipment that we use. These constraints still affect our observation efforts. We are now moving to install automatic weather stations which will feed into our data collection systems. Government is also coming in to support us with a radar system. We are expecting to take delivery of this system next year. Apart from this, there is also a thrust to have access to satellite data to augment our ground observation systems. We are not able to cover all the parts of the country but we are making do with what we have at the moment. Brain drain is still a problem and we need plans to retain more staff.
ST: How much do you think the Meteorological Services Department requires to ensure Zimbabwe has adequate weather stations and equipment across the country for reliable observations to be made?
BK: There is quite a lot that we expect to come in. When the budget was done, the needs for MSD were estimated at around US$30 million. This was what it was, but it’s not something that we could say will be exhaustive because there is quite a lot that is involved. For example, we envision to have a met station in every district.
We are also looking at having at least a rain gauge in every ward across the country. This is a mammoth task. Rainfall amounts are one of the most important variables. This will require more rain gauges, stations, more observers and more voluntary observers who can make observations from wherever they are. And when we get this information, it will make our observation more reliable. It will even improve our forecasting. The more the data you have, the better the forecast.
ST: Climate experts at the just-ended local and regional forums examined the potential impact of the wetter season forecast in the coming summer rainy season. What are some of the major problems that may face Zimbabwe in the forthcoming season?
BK: Each sector is impacted upon differently by a wetter rainfall season. There is a lot of mining activity that is happening and it’s degrading the environment. When you have a wetter season it will mean there is an increased possibility of flooding, erosion, drowning, siltation and dam breaches. Leaching and the outbreaks of water borne diseases are likely to increase too. Flash floods in areas with poor drainage may be a problem too.
ST: How best can farmers address some of the problems you have raised?
BK: Farmers must prepare and have adequate stock of fertilisers, chemicals, herbicides as they might not have conducive periods to do weeding and to control pests and diseases. Split application of fertiliser will be critical because of leaching. Farmers have to have enough stocks for split application of fertilisers. This is how they can get the best yields.
ST: Climate-related disasters have sadly been prominent in Zimbabwe and southern Africa in the past few decades. The impact of Cyclone Idai has been estimated at US$2 billion. What do you think is the role of early warning weather systems in reducing the impact of weather related disasters?
BK: The most recent IPCC report for 2021 says climate related disasters will increase, especially here in southern Africa and this will have a bearing on Zimbabwe too. We won’t be spared as a country. Early warning systems are critical in this regard. If you get an early warning, then you have to take prompt action. Forewarned is forearmed — once you have been informed you can then take appropriate action be it in the form of anticipatory action to reduce the impact.
We are coming to a point where we have to live with these disasters. If we prepare, we can save lives and assets. So it’s very critical to have sound early warning systems in place.
This builds the resilience of local communities to face climate related disasters.
ST: Are people in Zimbabwe and the SADC region taking early warning systems seriously? What role can local communities play in reducing the impact of weather related disasters given the information that you disseminate as the MSD?
BK: I would say it’s still a mixed situation in terms of reactions to early warning systems. Communities that have been affected by climate related disasters, have embraced early warning systems more than those who have not been affected.
It’s those that still have not experienced the climate related disasters who still have doubts and still lack the ability to change and embrace the early warning systems. Local communities play a huge role in reducing the impact of weather related disasters. These are the people on the ground and whatever information we generate, or whatever they have observed is important. We should not ignore the role of indigenous knowledge systems in weather forecasting within these communities. They also have ways of forecasting weather related disasters and how they can minimise their impact.
ST: As the MSD, do you have the capacity to acquire the meteorological data that is necessary to the effective operation of early warning systems in Zimbabwe?
BK: The Meteorological Services Department has 47 manned stations and over 500 rainfall stations across the country. The equipment goes a long way in recording and transmitting data that enables provision of meteorological (weather and climate) early warnings. However, there is much room for improvement, for example-most of the rain gauges are manual and they don’t transmit data automatically. Automated meteorological equipment like rain gauges can strengthen flood early warning systems as the data can feed directly into flood forecasting models. The other limitation is the capacity to forecast some hydromet hazards with accuracy. While meteorological drought can be forecasted with accuracy, hydrological, agricultural and socio-economic droughts cannot be easily forecasted in advance.