Seasonal rainfall predictability over the Lake Kariba catchment area

The Lake Kariba catchment area in southern Africa has one of the most variable climates of any major river basin, with an extreme range of conditions across the catchment and through time. Marked seasonal and interannual fluctuations in rainfall are a significant aspect of the catchment. To determine the predictability of seasonal rainfall totals over the Lake Kariba catchment area, this study used the low-level atmospheric circulation (850 hPa geopotential height fields) of a coupled ocean-atmosphere general circulation model (CGCM) over southern Africa, statistically  downscaled to gridded seasonal rainfall totals over the catchment. This downscaling configuration was used to retroactively forecast the 3-month rainfall seasons of September-October-November through February-March-April, over a 14-year independent test period extending from 1994. Retroactive forecasts are produced for lead times of up to 5 months and probabilistic forecast performances evaluated for extreme rainfall  thresholds of the 25th and 75th percentile values of the climatological record. The verification of the retroactive forecasts shows that rainfall over the catchment is predictable at extended lead-times, but that predictability is primarily found for austral mid-summer rainfall. This season is also associated with the highest potential economic value that can be derived from seasonal forecasts. A forecast case study of a recent extreme rainfall season (2010/11) that lies outside of the verification period is presented as evidence of the statistical downscaling system’s operational capability.Keywords: Lake Kariba catchment, coupled ocean-atmosphere model, statistical downscaling, seasonal forecasting, economic valu

Climate and southern Africa's water-energy-food nexus

In southern Africa, the connections between climate and the water-energy-food nexus are strong. Physical and socioeconomic exposure to climate is high in many areas and in crucial economic sectors. Spatial interdependence is also high, driven for example, by the regional extent of many climate anomalies and river basins and aquifers that span national boundaries. There is now strong evidence of the effects of individual climate anomalies, but associations between national rainfall and Gross Domestic Product and crop production remain relatively weak. The majority of climate models project decreases in annual precipitation for southern Africa, typically by as much as 20% by the 2080s. Impact models suggest these changes would propagate into reduced water availability and crop yields. Recognition of spatial and sectoral interdependencies should inform policies, institutions and investments for enhancing water, energy and food security. Three key political and economic instruments could be strengthened for this purpose; the Southern African Development Community, the Southern African Power Pool, and trade of agricultural products amounting to significant transfers of embedded water

Recent developments in Lablab purpureus genomics: A focus on drought stress tolerance and use of genomic resources to develop stress-resilient varieties

This research article published by John Wiley & Sons, Inc., 2021Drought is a major climatic challenge that contributes significantly to the decline of food productivity. One of the strategies to overcome this challenge is the use of drought-tolerant crops with a wide range of benefits. Lablab is a leguminous crop that has been showing high promise to drought tolerance. It is reported to have higher drought resilience compared with the commonly cultivated legumes such as common beans and cowpeas. Because of its great genetic diversity, Lablab can withstand high temperature and low rainfall, unlike other related crops. On top of that, it is grown for multitudes of purposes including food, forages, conservation agriculture, and improved soil fertility. To enhance its production and benefits during the present effects of climate change, it is crucial to develop improved varieties that would overcome the challenge of drought stress. In the past years, there have been several reviews on Lablab based on origin, domestication, characterization, utilization, germplasm conservation, some cultivation constraints, and conventional breeding with limitations on the genomic exploitation of the crop for drought tolerance. Conventional breeding is the major breeding technique for many Lablab cultivars. The integration of genomic, physiological, biochemical, and molecular approaches would be required to develop drought-tolerant cultivars of Lablab. In this review, we discuss recent developments in Lablab genomics with a focus on drought stress tolerance and the use of genomic resources to develop stress-resilient varieties