## 2 Materials and Methods
### Methods
#### 2.2.2 Basin Delineation Using GIS  
In geographic information systems (GIS), digital elevation models (DEMs) have been employed more and more frequently for basin delineation since they are tools used for the extraction of a large number of parameters necessary for a hydrological study [26]. However, in developing countries, urban basin divisions are usually not available [27; 28]. In this case study, there is no official delineation of publicly accessible urban basins. The available delineations present basins of large territorial extensions that do not have the level of detail for analysis of the surface water flow pattern in cities [29]. The delineation of an urban basin is complex, due to the layout of roads, subsurface, and surface drainage systems, as well as the modification of the natural terrain whose slopes are usually modified to adapt them to urban use. These factors make it difficult to perform a reliable delineation analysis of urban basin boundaries [30]. For this purpose, it is convenient to use the tools for the hydrological analysis of geospatial information systems (GIS). In this study, we used the methodology proposed by [PERSON] [25] and [PERSON] [18] to delineate urban basins from photogrammetry. This consisted of determining the highest elevations of the basin and the topographic \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Year** & **DMP (mm)** & **Year** & **DMP (mm)** \\ \hline
**1995** & 250.3 & **2009** & 69.9 \\
**1996** & 224 & **2010** & 69.9 \\
**1997** & 157.7 & **2011** & 67 \\
**1998** & 152.8 & **2012** & 67 \\
**1999** & 111.3 & **2013** & 60.8 \\
**2000** & 103 & **2014** & 60.2 \\
**2001** & 101.4 & **2015** & 59.5 \\
**2002** & 87.7 & **2016** & 58.3 \\
**2003** & 84.3 & **2017** & 58.2 \\
**2004** & 84 & **2018** & 55.4 \\
**2005** & 80.3 & **2019** & 54.5 \\
**2006** & 77.4 & **2020** & 51.6 \\
**2007** & 72.9 & **2021** & 39.7 \\
**2008** & 71 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Daily maximum precipitation at the station of the School of Biology [11]. Figure 2: Methodology for the standardization of urban hydrological studies. criteria of the study area to visualize the possible hydrological basins. Subsequently, the basins were delineated semi-automatically based on the digital terrain model (DEM) using the set of tools in QGIS 3.34.0 'Prizren' software for hydrological analysis. A minimum cell size was established to obtain the hydrological basins of the area under study. Next, the configuration of streets and storm drainage works such as ditches, canals, and sewers were considered. This was carried out to ensure that all surface runoff from each basin had a single exit point. It is important to point out that, in the watershed under study, stormwater runoff is conveyed only through the streets to a sinkhole from where it is drained through a drainage pipe placed under the ground. A Phantom 4 PRO UAV manufactured by DJI in Shenzhen, China was used to obtain a highly accurate and reliable digital elevation model (DEM). The UAV was flown at a height of 100 m with a speed of 15 m/s, a camera angle of 90 degrees, and horizontal and transverse overlaps of 75% and 70%, respectively. A total of 503 images were captured using a digital camera with a 20-megapixel resolution, i.e., with images of 2.5 cm spatial resolution. The flight lines and polygon were established using DJI's GSP-PRO software version v2.0. The images obtained from the photogrammetric flight were processed using Agisoft Metashape Professional software version 1.5.2, following the workflow proposed by [PERSON] et al. [31]. A pair of GNSS antennas (base and rover) were used to establish a network of ground control points (GCPs) in the study area. The base point was processed and adjusted according to Mexico's National Active Geodetic Network (RGNA), using the \"CULC\" station of the National Institute of Statistics and Geography (INEGI). The GCP network in the study area was measured using the real-time kinematic (RTK) technique.