water Article The Construction and Comparison of Regional Drought Severity-Duration-Frequency Curves in Two Colombian River Basins—Study of the Sumapaz and Lebrija Basins Laura Patricia Torres Rojas * and Mario Díaz-Granados Centro de Investigaciones en Ingeniería Ambiental (CIIA), Universidad de los Andes, Bogotá 111711, Colombia;
[email protected] * Correspondence:
[email protected]; Tel.: +57-1-339-4949 (ext. 1809) Received: 27 August 2018; Accepted: 18 September 2018; Published: 15 October 2018 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