MATERIALS AND METHODS

2.1. Study area

The study was carried out in the city of Manizales, capital of the department of Caldas, located in the central region of western Colombia, on the extension of the Andes. Manizales has its own mountain characteristics such as average slopes of 25% and an average altitude of 2,153 meters above sea level. Thanks to its geographical location, Manizales has a bimodal climate: each year there are two seasons of high rainfall and two of low rainfall (Vélez-Upegui, Duque-Méndez, Mejía-Fernández, & Orozco-Alzate, 2012). Due to its geographical location and due to its orography of great slopes, Manizales is home to snow-capped mountains, forests, mountains and valleys, making the relief of the city especially mountainous. The city has eight microclimates in its urban area with an average temperature of 18°C. During the rainiest months, the precipitation reaches values ​​between 100 and 500 mm, while during the least rainy months, the precipitation varies between 50 and 300 mm (Vélez-Upegui et al., 2012). The two annual low rainy seasons begin with the solstices on June 22 and December 21, and the two high rainy seasons begin with the equinoxes on March 21 and September 22.
12 meteorological stations and a hydrometeorological station were used, distributed in the urban area of Manizales (Figure 1), which belong to the network for risk management due to landslides that measure rainfall every five minutes and which are managed by the Universidad Nacional de Colombia in Manizales. The information is available in a data warehouse called the Caldas Environmental Data and Information Center (CDIAC by its name in Spanish) (IDEA UN Manizales & CORPOCALDAS, 2015). The oldest station was installed in 2002. The common period between the stations analyzed is 2010-2018 for the analysis of the day cycle, however, the 2006-2014 period was used for event analysis of the events. It is not possible to carry out longer-term studies, such as an extreme frequency or climatic variability analysis, with the data available, so these were not included.
Figure 1 . Location of the city of Manizales and location of the hydrometeorological stations

Methodology

The information downloaded from the CDIAC was analyzed (http://cdiac.manizales.unal.edu.co/inicio/). Filters were used to correct and depurate the data: those outside the sensor measurement ranges, or known physical ranges, and those with significant differences in the continuity of the records according to the precipitation values ​​were specifically eliminated, while measurement errors sensors were reviewed. Finally, data consistency and homogeneity were analyzed, obtaining the records from Table 1. The consistency analysis was carried out using an accumulated double mass analysis, accumulating the diurnal rains from each of the stations and graphing them with each other. Higher slopes were found in comparison with El Carmen; smoother slopes when compared with La Palma, Bosques del Norte and Aranjuez; while Posgrados and Emas were identified within an intermediate group. For Yarumos, the beginning is similar to the rainiest parts of the city, but the final part has a slope more similar to the less rainy areas. The discontinuity in the slopes is explained by missing data or because the origin of the rains is different. The homogeneity analysis was performed using statistical tests that measure changes in mean and variance. For diurnal rainfall, the use of consistency analysis is considered appropriate.
Table 1. Summary of precipitation records for network stations for landslide risk management in the city of Manizales
Once these analyzes were carried out and based in the precipitation data with a five-minute temporal resolution Pi , the hourly values Pmha were obtained, from which the monthly mean values were obtained for each hour h of each year a , m (m = 1,…., 12), a (a = 1,…, na) averaging the values of every day of the year for each hour (Eq. 1).