Abstract
Central America is frequently affected by droughts that cause significant socio-economic and environmental problems. Drought characterisation, monitoring and forecasting are potentially useful to support water resource management. Drought indices are designed for these purposes, but their ability to characterise droughts depends on the characteristics of the regional climate and the quality of the available data. Local comprehensive and high-quality observational networks of meteorological and hydrological data are not available, which limits the choice of drought indices and makes it important to assess available datasets. This study evaluated which combinations of drought index and meteorological dataset were most suitable for characterising droughts in the region. We evaluated the standardised precipitation index (SPI), a modified version of the deciles index (DI), the standardised precipitation evapotranspiration index (SPEI) and the effective drought index (EDI). These were calculated using precipitation data from the Climate Hazards Group Infra-Red Precipitation with Station (CHIRPS), the CRN073 dataset, the Climate Research Unit (CRU), ECMWF Reanalysis (ERA-Interim) and a regional station dataset, and temperature from the CRU and ERA-Interim datasets. The gridded meteorological precipitation datasets were compared to assess how well they captured key features of the regional climate. The performance of all the drought indices calculated with all the meteorological datasets was then evaluated against a drought index calculated using river discharge data. Results showed that the selection of database was more important than the selection of drought index and that the best combinations were the EDI and DI calculated with CHIRPS and CRN073. Results also highlighted the importance of including indices like SPEI for drought assessment in Central America.
Highlights
The quantification and understanding of drought characteristics is necessary for water management and planning, especially in a region like Central America where droughts occur frequently and lead to large economic and social problems
This is likely caused by errors in the source data used to create the gridded datasets
The analysis at the annual scale confirmed those at the monthly scale, meaning that Climate Hazards Group Infra-Red Precipitation with Station (CHIRPS) and CRN073 were good at capturing the characteristic climate of the region
Summary
The quantification and understanding of drought characteristics is necessary for water management and planning, especially in a region like Central America where droughts occur frequently and lead to large economic and social problems. Reduced water levels in surface and subsurface water bodies increase the costs of water extraction and mean that alternative—usually more expensive—ways of providing drinking water are needed, which in turn may increase the costs of water treatment. All these negative effects, do not occur simultaneously. Deficits in soil moisture and, effects on agriculture, are usually not observed until after a period of sustained precipitation deficits (meteorological drought), and it may take an even longer period for deficits to occur in surface and subsurface water bodies (hydrological drought). Short accumulation times are used to estimate meteorological drought (e.g. 1, 3 months), medium accumulation times are used for agricultural drought (e.g. 3, 6 months) and long for hydrological drought (e.g. 6, 12 months)
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