APPLICATION OF THE EMS-WRF MODEL IN DEKADAL RAINFALL PREDICTION OVER THE GHA REGION

The IGAD Climate Prediction and Applications Centre exists to monitor and predict the patterns of rainfall over the greater Horn of Africa region, and provide early-warning products and information, particularly concerning recurrent drought episodes and localized flooding. Forecasting on dekadal (ten-day) timescales is critical because it is the bridge that links short term scales, called the NWP range, and seasonal scales. This study seeks to assess the validity of downscaled GCM rainfall outputs by the Environmental Modelling System’s Weather Research and Forecasting (EMS-WRF) model in 2011. The results reveal that the EMS-WRF model, by and large, performs well over the region, but the excellence of the forecast products varies temporally and spatially. Nonetheless, the model exaggerates rainfall amounts over certain areas, particularly that forced by mesoscale systems. Moreover, the model generally underestimates the rainfall amounts arising from unexpected storms, and displaces the areas of the highest rainfall intensity in several respects. The EMS-WRF model is useful for predicting the distribution of dekadal rainfall over the GHA, but may perform better through improving the ocean-atmosphere interactions and feedback processes and employing multi-model ensemble forecasting techniques. The model should be used cautiously in tandem with other forecasting techniques.Key words: EMS-WRF model, rainfall, prediction, forecasting, dekad, dekadal, ICPA

Simulated Impacts of Climate Change on Surface Water Yields over the Sondu Basin in Kenya

Potential impacts of climate change on surface water yields over the Sondu River basin in the western region of Kenya were analysed using the Soil and Water Assessment Tool (SWAT) model with climate input data obtained from the fourth generation coupled Ocean-Atmosphere European Community Hamburg Model (ECHAM4) using the Providing Regional Climates for Impacts Studies (PRECIS) model. Daily time step regional climate scenarios at a spatial grid resolution of 0.44Ëš over the Eastern Africa region were matched to the Sondu river basin and used to calibrate and validate the SWAT model.Analysis of historical and projected rainfall over the basin strongly indicated that the climate of the area will significantly change with wetter climates being experienced by 2030 and beyond. Projected monthly rainfall distribution shows increasing trends in the relatively dry DJF and SON seasons while showing decreasing trends in the relatively wet MAM and JJA seasons. Potential changes in water yields resulting from climate change were computed by comparing simulated yields under climate change scenarios with those simulated under baseline conditions. There was evidence of substantial increases in water yields ranging between 88% and 110% of the baseline yields by 2030 and 2050 respectively. Although simulated water yields are subject to further verification from observed values, this study has provided useful information about potential changes in water yields as a result of climate change over the Sondu River basin and in similar basins in this region

Forage Monitoring and Prediction Model for Early Warning Application over the East of Africa Region

Rangelands dominate arid and semi-arid lands of the Greater Horn ofAfrica (GHA) region, whereby pastoralism being the primary source oflivelihood. The pastoral livelihood is affected by the seasonal variabilityof pasture and water resources. This research sought to design a grid-basedforage monitoring and prediction model for the cross-border areas of theGHA region. A technique known as Geographically Weighted Regressionwas used in developing the model with monthly rainfall, temperature,soil moisture, and the Normalized Difference Vegetation Index (NDVI).Rainfall and soil moisture had a high correlation with NDVI, and thusformed the model development parameters. The model performed wellin predicting the available forage biomass at each grid-cell with March-May and October-December seasons depicting a similar pattern but witha different magnitude in ton/ha. The output is critical for actionable earlywarning over the GHA region’s rangeland areas. It is expected that thismode can be used operationally for forage monitoring and prediction overthe eastern Africa region and further guide the regional, national, sub-national actors and policymakers on issuing advisories before the season

Understanding the role of user needs and perceptions related to sub-seasonal and seasonal forecasts on farmers decisions in Kenya: a systematic review

One major challenge facing farmers and other end-users of weather and climate information in Kenya is the linkage between their perceptions, needs and engagements with producers of the information. This is highlighted by increased interest in understanding the constraints on appropriate use of weather and climate information by farmers in decision making. Farmers face extreme weather impacts which constraint the use and choice of the appropriate weather information and other services. The choice between sub-seasonal and seasonal forecasts can enable better decisions by farmers if the forecast information is reliable and integrated through a co-production process.The objective of this study was to analyse the user needs and perceptions of crop farmers, pastoralists and agro-pastoralists in relation to sub-seasonal and seasonal forecasts for 5 counties in Kenya. A total of 200 peer-reviewed and grey literatures were systematically reviewed to understand how the needs and perceptions of users of weather and climate information shaped access and use in decision making. The study also reviewed whether sub-seasonal and seasonal forecasts were adopted and used appropriately.Results show that farmers' perceptions shaped the choice of weather and climate information while sub-seasonal and seasonal forecasts were used for diverse applications. Gender, availability of resources, access and mode of communication were some of the factors influencing use of the information. One lesson learnt was that farmers combined weather and climate information with other coping practices such as agronomic practices and water efficiency management. However, a number of challenges were faced by the users such as insufficient resources, lack of access to information and poor engagement with weather forecasters and extension services.2 This is a provisional file, not the final typeset article This study recommends stakeholder engagements with producers in development of products and services to improve uptake and use of forecasts in decision making