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).