An integrated hydrological drought assessment: evaluation of ENSO, meteorological and hydrological indexes for the Chagres River Basin

Abstract

The Chagres River basin contemplates several activities such as providing water to the Panama Canal operations, water supply to the population, hydropower generation, among others. Currently, water scarcity has been reported due to the activities in the basin and has been attributed to ENSO phenomena and climate change. Lack of precipitation could possibly induce a hydrological drought presence, which is characterised by negative water source anomalies at the surface or subsurface. For that reason, a hydrological drought assessment was performed for the Alhajuela sub-basin. The methodology consists of performing a hydrological characterization and a hydrological drought characterization while using the threshold estimation method, standard precipitation index, standard streamflow index, and the evaluation of ENSO presence with the ONI index. Hydrological characterization demonstrates the basin has a high correlation between the principal rivers: Chagres, Pequeni and Boqueron, which leads to a system that storms bigger than their total area, and a similar recession index may indicate a similar infiltration rate and similar properties regarding their hydrogeology. Hydrological drought assessment results show that most drought events are considered short in duration, deficit volume and intensity in the presence of normal, weak La Niña and weak El Niño, and mild wet and mild drought for the SPI and SSFI. Long-lasting drought events are strongly linked to strong El Niño. In conclusion, the system faces a slight effect of hydrological droughts and may be considered extreme with the presence of ENSO El Niño.