Automation of hydrological drought typology to study drought propagation in a tropical catchment

• Understanding different types of drought and how they propagate through the hydrological cycle from precipitation to streamflow and groundwater deficits is important for improving water and risk management policies. Drought in the tropics is a recurrent phenomenon, but limited knowledge exists about drought severity and duration as well as the processes that cause different types of drought. At the catchment scale, analysing drought propagation is usually done manually. This can be time consuming (e.g. when dealing with long time series or many catchments) and may introduce subjective elements into the analysis that affect the comparability between catchments and studies. In this study, we developed a methodology to provide an automated objective procedure for drought typology to study hydrological drought propagation in the tropics.  We selected the Savegre catchment in Costa Rica as a proof-of-concept pilot study. The first step was to analyse if the types of drought affecting this catchment could be explained in terms of the process-based typology available in the literature: classical rainfall deficit drought, wet-to-dry season drought, and composite drought. Then, based on the manual typology, we defined different criteria for the hydrological drought types to make the typology automated and objective. Finally, we analysed drought propagation using a set of duration, timing and deficit indicators. We found that the process-based hydrological typology available in the literature is suitable to describe the different drought processes occurring in Savegre. The classification obtained with the automated typology was highly similar to the manual typology, with the exception of one event. We found that most of the detected droughts (71% and 73% from all river discharge and groundwater droughts, respectively) were classical rainfall deficits droughts, which suggests that droughts in this catchment are highly climate dominated. However, the importance of storage control was reflected during the dry season, when some of the longest and most severe events took place. The most severe events were composite and wet-to-dry season droughts, but we also found highly severe classical rainfall deficits droughts. Our results can potentially be applied to the wider tropics facilitating automatic drought classification using process-based selection criteria. Our study contributes to the overall knowledge of drought propagation in tropical catchments and is useful for supporting drought monitoring and forecasting, which is a much needed tool for water and drought-related disaster management in the tropics. 

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Oceanografi, hydrologi och vattenresurser (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Oceanography, Hydrology and Water Resources (hsv//eng)

Nyckelord

drought propagation; drought typology; automation; tropical catchment; Central America; Costa Rica

Hydrology

Hydrologi

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)