Abstract
Accurate classification of drought-severity is one of the most challenging issues in designing regional monitoring and control plans, especially in developing countries, where resources are scarce and must be carefully optimized to maximize social benefit. Typically, drought assessment is performed using drought indices which enable the interpretation of complex climatic information series for operational purposes. Frequency analyses are also useful for estimating future occurrence probabilities, even on regional scales. This study generated regional Severity-Duration-Frequency (SDF) curves for two Colombian catchments (Sumapaz and Lebrija River Basins), and 7 index-calculation procedures. First, the relationships between the two catchments were analyzed to obtain differences between drought indices. Second, the consistency among the indices that identified the same drought types for each region was evaluated. Finally, historical regional drought occurrences were selected, characterized, and located in local SDF curves to determine their gravity. It was concluded that (i) curves for the same indices displayed similar behavior, when comparing the two case studies; (ii) a certain degree of consistency existed in regional curves, which identify the same drought types (meteorological and agricultural droughts being the most coherent); (iii) meteorological drought regional events, identified through different drought-indices methodologies, were the most common for both case studies, followed by agricultural droughts and hydrological droughts; (iv) when analyzing occurrences with higher return periods, there is coherence when using different methodologies; and (v) identified historical events, which are located on larger return period zones of SDF curves (around 10, 25, and 50 years), had large impacts on regional socio-economic issues. Hence, it was possible to confirm that regional SDF curves could become potentially useful tools for the prioritization of drought-vulnerable zones.
Highlights
Drought is one of the most serious and complex threats that humankind must deal with.According to the Food and Agriculture Organizatio (FAO) (2018) [1], for the 2005–2015 period, drought was the most expensive disaster in Latin America and the Caribbean
Palmer Hydrological Drought Index (PHDI) could not be included in any of the categories because of its lack of complete agreement with other indices that identify hydrological droughts. This grouping was useful because it facilitated the identification of Drought Indices (DI) methodologies that led to consistent results, and in terms of regional planning and operation, allowed those indices with simpler calculation procedures and fewer information requirements to be selected as monitoring tools, optimizing work and resources
Iso-severity maps constructed for maximum possible durations and return period (50 years) are displayed in it is important to mention that, as can be seen in Figure 5a, the most severe drought occurrences are concentrated on the southern and eastern regions of the Lebrija River basin (LRB), except for SPI3 and SPI6, which showed higher magnitudes for stations located on the western zone of the catchment
Summary
Drought is one of the most serious and complex threats that humankind must deal with. According to the Food and Agriculture Organizatio (FAO) (2018) [1], for the 2005–2015 period, drought was the most expensive disaster in Latin America and the Caribbean. The associated losses for that lapse of time reached US $13 billion and were related with crop and livestock affectations. South and Central American economies rely significantly on rain-dependent crops, i.e., about 80% of total regional agricultural yield production is related to rain-fed crops [2]. A large percentage of the GDP of these countries is associated with agriculture [2], and the zone produces and exports almost. 11% of the global food supply [3]. Vulnerable areas include north and central regions of
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