RESUMEN
River widening, defined as a lateral expansion of the channel, is a critical process that maintains fluvial ecosystems and is part of the regular functioning of rivers. However, in areas with high population density, channel widening can cause damage during floods. Therefore, for effective flood risk management it is essential to identify river reaches where abrupt channel widening may occur. Despite numerous efforts to predict channel widening, most studies have been limited to single rivers and single flood events, which may not be representative of other conditions. Moreover, a multi-catchment scale approach that covers various settings and flood magnitudes has been lacking. In this study, we fill this gap by compiling a large database comprising 1564 river reaches in several mountain regions in Europe affected by floods of varying magnitudes in the last six decades. By applying a meta-analysis, we aimed to identify the types of floods responsible for more extensive widening, the river reach types where intense widening is more likely to occur, and the hydraulic and morphological variables that explain widening and can aid in predicting widening. Our analysis revealed seven groups of reaches with significantly different responses to floods regarding width ratios (i.e., the ratio between channel width after and before a flood). Among these groups, the river reaches located in the Mediterranean region and affected by extreme floods triggered by short and intense precipitation events showed significantly larger widening than other river reaches in other regions. Additionally, the meta-analysis confirmed valley confinement as a critical morphological variable that controls channel widening but showed that it is not the only controlling factor. We proposed new statistical models to identify river reaches prone to widening, estimate potential channel width after a flood, and compute upper bound width ratios. These findings can inform flood hazard evaluations and the design of mitigation measures.
RESUMEN
INTRODUCTION: Percutaneous coronary intervention (PCI) remains a major therapeutic tool in the management of acute coronary syndromes (ACS). However, it is not widely practiced in sub-Saharan Africa, particularly for the management of ACS. The availability of a catheterization laboratory for 24-hour management of ACS in Dakar is an important step in improving the prognosis of patients. The objective of our study was to evaluate the clinical and prognostic profile of patients presenting an ACS and treated by PCI. PATIENTS AND METHODS: This is a retrospective study that included all patients who underwent PCI for ACS at hospital principal Dakar during the period from January 2019 to December 2020. RESULTS: Our study included 112 patients with a mean age of 60 years (extremes 31-96 years) and a male predominance (sex ratio 4.09). Cardiovascular risk factors were dominated by hypertension (47.3%) and smoking (39.3%). Chest pain was present in 97% of patients. Left ventricular systolic function was impaired in 56 patients with a mean of 50% and extremes of 20 and 78%. Thrombolysis with streptokinase was used in 13 patients with STEMI. The majority of coronary angiogram (95%) were performed between 8 am and 5 pm. The radial route was the most commonly used (85.7%). Double vessel coronary artery disease was predominant (39,3%) and the left anterior descending artery was the most affected (60.7%). The PCI was performed in all patients and in more than half of the cases (55%) within 12 hours of delay. The PCI success rate was 96.4%. Sixty-seven patients (59.8%) underwent balloon predilation. PCI was performed with a drug-eluting stent in the majority of patients (92.8%). The outcome was favorable in 96.4% of the patients, but there were 3 deaths (2.7%). CONCLUSION: Treatment of ACS by PCI is a reality in Senegal with a considerable success rate. However, intervention delays remain one of the major challenges of this management.
