Development of a drought and yield assessment system in Kenya

Dependence on rainfed agriculture in a highly variable climate, renders crop and livestock production vulnerable to impacts of drought in Kenya. The need for timely and actionable detailed early warning information on drought and its implication on crop productivity for decision making has been explicitly expressed by food security stakeholders. In response to the need and with support with the NASA Jet Propulsion Lab, the Regional Hydrological Extremes Assessment System (RHEAS) was developed with the capability of estimating seasonal conditions and determining drought onset, severity, recovery, and duration; and expected productivity outlook.

RHEAS is an easily scalable open source system that is made up of a hydrological model (Variable Infiltration Capacity Model, VIC) and cropping system model (Decision Support System for Agro-technology Transfer, DSSAT). With a spatially enabled database, the system is able to automatically ingest, manage and assimilate a multitude of remotely sensed and in-situ data sources, execute multiple queries for optimized performance and generate nowcasts, forecasts and climatological trends. Due to the general lack of in-situ data for effective crop model simulations, outputs from VIC are assimilated into the DSSAT model. The Ministry of Agriculture, Livestock, Fisheries and Irrigation (MOALFI) has supported the customization of the model by providing data for validation and informing estimation of inputs applied in different production zones. Further, the system has been customized using a detailed cropland mask and calibrated using altitude specific cultivars for the DSSAT model. Initial maize yield simulation results matched expected variations in yields during drought and good years and correlate well at 0.77 against national production trends from the Food and Agricultural Organization (FAO) for the country.