Risk and vulnerability to drought in New Brunswick.

In Canada, hydroclimatic hazards represent more than 90% of the country’s natural hazards. In New Brunswick (NB), the risk of flooding has been extensively studied, particularly along the Saint John River, where damage is significant and frequent (Duhamel et al., 2022; Fortin et al., 2021). However, drought risk is rare and understudied in this province. In this presentation, we describe the risk of droughts over 50 years (1971-2020) based on different approaches. For example, various drought indices, such as the Standardised Precipitation Index (SPI), the Standardised Precipitation Evapotranspiration Index (SPEI), Palmer Drought Severity Index (PDSI), and Standardized Evapotranspiration Deficit Index (SEDI) based on data from about ten meteorological stations across NB, are presented. To represent the spatial variability of the driest summers (JJA) we also used the Vegetation Health Index (VHI), which was obtained from the Vegetation Condition Index (VCI) and the Temperature Condition Index (TCI). We calculate these indices from satellite images (MODIS-TERRA). Finally, we attempt to figure out vulnerability sub-indices (sensitivity and exposure) to identify drought risk in the population. 

Our results indicate a slight increase in drought events, but this varies by index (e.g., SPI, SPEI, etc.) and period (1, 3, 6, or 12 months). For example, for SPEI3 (summer), we detected a statistically significant increasing trend for 6 of 10 stations between 1971 and 2020. In addition, all ten weather stations experienced moderate to severe drought throughout the study, according to the calculated PDSI and SEDI values.  The recent increase in temperature is likely to favor higher evapotranspiration, which could partially explain the observed increase in droughts. Using satellite images has made it possible to classify pixels according to the level of drought. Still, there is much heterogeneity, so it is difficult to distinguish the areas most affected by drought and, therefore, the most vulnerable areas.  Among the vulnerable areas of NB, the stations near the coast (eastern NB) seem more exposed to severe drought than inland stations.

Finally, to properly represent a vulnerability to droughts, it is necessary to combine different sub-indices: sensitivity, exposure, and adaptation. We will discuss the limitations of the available data and possible solutions to try to substitute these data.