Current and future drought hazards in the Flemish pear sector

Recurring episodes of drought have become a hot topic in recent years in the Flemish pear sector. Damages associated with these episodes increasingly cause economic losses and create uncertainty for fruit growers. This trend is expected to continue in the future, as episodes of drought are likely to increase in frequency, intensity and duration as a result of climate change.

This problem calls for the development of efficient risk management methods, which rely on accurate estimates of the hazard imposed by extreme weather. Therefore, our study aims to quantify the location-specific hazard and impact of past and projected drought episodes on pear orchard vigour and productivity in the region of Flanders (Belgium). The hazard under the recent past climate is characterised based on daily historical meteorological observations (1961-2022) with 5x5 km spatial resolution (Gridded Observational Dataset of the Royal Meteorological Institute of Belgium). The future hazard is determined based on daily regional climate model projections from the CORDEX ensemble (12.5x12.5 km spatial resolution). Climate projections are bias-corrected using Multivariate Quantile Mapping based on a N‐dimensional probability density function transform.

Regional AquaCrop, a spatially distributed modelling system of the field-scale crop growth model AquaCrop¹, is used to calculate the soil water balance on a daily timestep, covering the region of Flanders at a spatial resolution of 12.5x12.5 km. Phenology-dependant thresholds of critical values of the soil water potential are used to analyse the frequency, intensity, duration and timing of drought-related stress episodes for rainfed pear orchards (cv. Conférence). Moreover, changes in the characteristics of potentially damaging episodes of drought under future climates are analysed.

Preliminary findings show an increase in projected frequencies of stress-inducing occurrences under Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 for the period 2022-2072 compared to the reference period 1972-2022. Moreover, spatial variation in drought hazards for pear orchards across Flanders points to local environmental factors such as soil type and groundwater depth.

The spatially explicit hazard maps associated with the future climatic conditions resulting from this analysis are useful for decision-making by fruit growers, governments and insurance companies.

 

¹Raes, D., Steduto, P., Hsiao, T. C., and Fereres, E.: AquaCrop – the FAO crop model to simulate yield response to water: II. Main algorithms and software description, Agron. J., 101, 438–447, https://doi.org/10.2134/agronj2008.0140s, 2009.