Modeling urban drainage in intermediate cities under extreme climate change scenarios: a case study in Southeastern Tunja, Colombia Open Access

Currently, most of the population lives in urban centers because of the ease of access to different services that increase the well-being of families (Brenner & Schmid 2016). This constant population migration to urban areas brings economic, social, cultural, and environmental changes (Bettencourt et al. 2007; Van Praag & Timmerman 2019). In essence, unemployment, increased poverty, insecurity, events such as war, armed conflict, and political and economic ideals are the leading causes of this migration (Ibáñez & Vélez 2008). These population increases in cities are also related to the demand for goods and services, including housing and buildings, which implies the expansion of the basic urban services. (Busso et al. 2021). The construction and expansion of a city requires space to develop, i.e., a site or place to settle. The demand for space by a city indicates that a natural system must be altered, causing a series of changes and disturbances in the territory (Jedwab et al. 2021). However, without proper planning, there is a risk of unplanned slums and the potential threat of turning small municipalities into unplanned megacities lacking good territorial organization (Son et al. 2023).

Water is a resource that plays a vital role in society as it is an indispensable factor in shaping and sustaining economic growth and welfare (Liu & Liu 2021; Yang 2022), through activities such as agriculture, energy production, industry, transportation, and tourism (Cohen & Herman 2021). Also, water is a dynamic resource, and through its hydrological cycle, it changes states naturally. In this context, the construction or expansion of urbanized areas alters the characteristics of the soil, making them impermeable to the passage of rainwater, generating more significant volumes of runoff in precipitation events by interrupting the infiltration phase into the subsoil as part of the natural cycle (Wiechman et al. 2024). As they cannot infiltrate the soil, the volumes of water retained on impervious surfaces cause a series of negative impacts in the urbanized sector, such as flooding, water stagnation, alterations in the relief, and public health problems (Park et al. 2020). These impacts limit the quality of life of the area's inhabitants; therefore, runoff water requires comprehensive management that allows its control and regulation to moderate flood risks and their negative impacts.

Human security in the face of environmental risks means protection against unpredictable events that may disturb or alter lives and livelihoods (Sarmah et al. 2020). Therefore, one of humanity's main challenges today is facing the consequences of accelerated climate changes, which impact the environment, society, and the economy (Membele et al. 2022). In particular, global warming causes the hydrological cycle to alter, increasing evaporation and precipitation (Lambert et al. 2008). The second report of the Intergovernmental Panel on Climate Change (IPCC) warns that global warming will increase floods and droughts (Yin et al. 2021). Because of this, and due to humanity's technological, economic, institutional, and cultural conditions, global water management faces significant challenges, as these factors are transforming the environmental conditions day by day (Li et al. 2022). However, this problem has been addressed by specialists worldwide, who have concluded that the climate also changes due to natural causes apart from those of anthropogenic origin.

As mentioned above, due to urbanization, different areas have been built for housing and transportation, which have become impermeable to water infiltration (Parnas et al. 2021). This generates a change in the hydrological cycle so that infiltration and groundwater recharge of aquifers decrease with this process (Beetle-Moorcroft et al. 2021). In all planning and development of urban areas, the designs of artificial structures and activities related to water management in cities must take into account local climatological and hydrological conditions, as well as the behavior and interaction with the rural area of the city in the face of future urban development (Grimmond et al. 2020). Most developing countries experience a deficit in this infrastructure for rainwater and flood management (Haque et al. 2020). Water management risk mitigation through flood control systems and economic infrastructure development has been fundamental to human progress in many industrialized countries (Thorne et al. 2018).

In this regard, the design and implementation of effective drainage networks, whether through conventional sewerage or alternative sanitation solutions, are essential for protecting public health and ensuring urban resilience. However, the high construction costs are the problem of adapting urban drainage systems due to low budgets, especially in developing countries such as Colombia (Ortega et al. 2023). Due to the phenomenon of urbanization in recent years, intermediate cities, defined as urban areas that act as regional hubs with growing demographic and economic importance (Llop et al. 2019), are expected to become the large cities of the future (Kourtis & Tsihrintzis 2021); therefore, comprehensive planning, understood as the integrated planning of drainage and sanitation infrastructure, including both the design of the network and its articulation with other urban infrastructure solutions, or the reform of existing storm drainage systems should be contemplated. This planning must outline a forward-looking vision that considers the possible impacts of climate change on urban flooding during extreme precipitation events, with the ultimate goal of strengthening basic sanitation, promoting social welfare, and restoring balance in the hydrological water cycle.

Considering the previous context, it is crucial to solve the problem of storm drainage in intermediate cities (Llop et al. 2019), to prevent the negative impacts caused by extreme climate changes in this type of urbanized sector. Based on this research problem, the objective of this study is to model rainwater drainage in the southeastern sector of Tunja, an intermediate city located in the Department of Boyacá, Colombia. The study establishes different extreme climate change scenarios, assesses the potential consequences of these phenomena, and defines both the scope of the problem and possible solutions. The evaluation of the urban drainage system was conducted using data provided by the national communications of the Institute of Hydrology, Meteorology and Environmental Studies of Colombia (IDEAM).

According to UNESCO (1999), the definition of ‘intermediate city’ includes those with a population of more than 100,000 but fewer than one million inhabitants. Tunja currently has, according to the latest estimates of the National Administrative Department of Statistics (DANE 2018), about 200,000 inhabitants, making it an ‘intermediate city.’ In turn, the city of Tunja has a linear urban growth pattern due to the physical conditions imposed by the relief and the dynamics generated by the central road to the north and the eastern avenue to the south (Rojas Gamba et al. 2021). The spatial configuration of the city of Tunja depends mainly on national dynamics and policies and, to a lesser extent, on generating projects at the local level (Echeverría et al. 2019).

The city mostly has a combined sewage system, where rainwater mixes with wastewater and is transported to the wastewater treatment plant (WWTP), to later be discharged into water bodies. However, during heavy rainfall periods, the capacity of the sewage system is exceeded, causing flooding in the city's lower areas (Alcaldia Mayor de Tunja 2022). Due to its age, associated with more than 50 years of existence, (Rodríguez Gonzalez et al. 2020), and the useful life of its materials, this system presents problems and irregularities in its operation. These are especially evident in high rainfall, and sectors are determined mainly by their topography (Arevalo Algarra et al. 2021). The average total annual rainfall in Tunja is 652 mm. During the year, rainfall occurs in two dry and two rainy seasons. According to records made by the IDEAM meteorological station located in the city, the months with the highest rainfall are April and October, and the hours with the highest rainfall are between 15:00 and 18:00 (IDEAM 2024).

Considering that Tunja is an intermediate city in constant urban growth, the different stakeholders such as local government authorities, environmental agencies, and urban planning agencies are interested in contemplating a comprehensive planning or reform of the storm drainage systems, outlining a vision for the future that allows considering the possible variations of climate change in the problem of rainwater flooding. Therefore, modeling extreme climate scenarios is essential for informed decision-making in urban planning, basic sanitation, social welfare, and maintaining balance in the hydrological water cycle.

Tunja is divided into four zones: northeast, northwest, southeast, and southwest. For the modeling, the southeast zone was analyzed. The southeastern zone is subdivided into seven drainage districts (Alcaldia Mayor de Tunja 2024), of which the eastern road district was studied. The areas of the different drainage districts are smaller than 80 ha. Therefore, it is possible to use the rational method used by the SWMM software to determine the runoff resulting from the different rainfall scenarios.

Various dynamic and statistical models were developed by IDEAM and it is possible to calculate future changes in climate-related variables. Following the methodological routes proposed by the IPCC – Intergovernmental Panel on Climate Change (2024) for the department of Boyacá, an increase in precipitation of 5.84% is estimated for the period 2011–2040; for the period 2041–2070, a decrease of 3.69% is projected; and finally, for the period 2071–2100, a decrease of 3.19% is expected. For the specific case of the city of Tunja, an overall increase in precipitation of 30% is expected from 2011 to 2100, with 14% projected for the period 2011–2040, 9% for 2041–2070, and 7% for 2071–2100 (IDEAM 2021).

To model urban drainage, the Caminos de Oriente urban area, located in the city's southeastern sector, was analyzed. This area was chosen because of the ease with which it is possible to carry out planning related to the design of collectors; in addition, its sewerage system is planned to be separate and, therefore, different from the city's traditional system. This proposed drainage system has not yet been constructed; it is in the planning and design phase and is envisioned to be a closed pipe (storm sewer) system, consisting of fully buried infrastructure with point catchment inlets.

For this purpose, and taking into account the recommendations suggested by the Water and Basic Sanitation Regulations (Reglamento Técnico Del Sector de Agua Potable y Saneamiento Básico (RAS) 2016), the dynamic precipitation simulation model ‘Storm Water Management Model (SWMM)’ of the United States Environmental Protection Agency (EPA 2024) was applied. This model makes it possible to simulate the quantity and quality of water evacuated by sewers in a continuous event or simulation over a long period. It analyzes the path of water through a specific system and the evolution of the quantity and quality of runoff water. For Tunja, sewer sections were taken from tributary areas between 2 and 10 ha, for which a 5-year return period was recommended. This return period was selected based on technical criteria commonly used in urban drainage design in Colombia.

In particular, the Ministerio de Vivienda (2017) establishes that for drainage areas under 80 ha, the rational method may be applied, and practice has shown that a 5-year return period is suitable for local drainage systems serving areas between 2 and 10 ha. This criterion has also been adopted in technical guidelines by public utility companies and planning entities in other Colombian cities, as it represents a balance between protection against frequent rainfall events and the economic feasibility of infrastructure (Empresas Municipales de Cali (EMCALI) 2023). Once these data were selected, rainfall periods were defined, taking into account the analysis of hourly rainfall carried out by IDEAM for the city's hydrometeorological station. Three storm periods were established: 1, 3, and 6 h, since these three precipitation events usually occur in the city during the rainy season.

With the values of a 5-year return period of the intensity–duration–frequency (IDF) curves, the intensity values expressed every 15 min over a total duration of 6 h were obtained. A linear interpolation was performed for the intervals without recorded data and the total precipitation value was calculated. Although the design is based on a 5-year return period event, an additional adjustment was carried out to explore the behavior of the system under more severe conditions, without involving a new formal return period. This adjustment was carried out in two stages. The first consisted of calibrating the precipitation data to the maximum historical precipitation recorded in the last 20 years. In the second step, a 14% increase was applied to this adjusted value, following the climate change projections issued by IDEAM and the SAN guidelines. The result was used to define three pluviometric scenarios (see Tables 2–4), which serve as hypothetical stress tests to evaluate the resilience of the drainage system to plausible extreme events.

The sewer network in Tunja is composed mainly of combined systems, with separate sanitary and stormwater infrastructure being implemented in recent developments as required by the local water utility (Veolia Aguas de Tunja S.A. E.S.P.). Although the specific diameters of the pipes vary throughout the city and were defined according to the tributary areas in each modeled sub-catchment, typical conveyance pipes in the study area range between 300 and 1,000 mm in diameter, using circular PVC sections. Larger collectors and interceptors can reach up to 1,200 mm or more, depending on the sector (Alcaldia Mayor de Tunja 2024).

Particularly, the soil in the study area consists mainly of clay and sand, with a Manning coefficient of n = 0.012 for concrete and n = 0.15 for grass. The altitude ranges between 2,700 and 2,774 meters above sea level (m.a.s.l.). The pipe material used is PVC, with a Manning coefficient of 0.008. The city has a colonial urban layout with squares approximately 120 meters in size. About 80% of the soil is occupied. The pipes are circular in shape, and the box culverts are typically circular as well. The land slopes vary between 0.5 and 2%. Finally, the pipes have a slope ranging from 0.29 to 10%.

The implementation of Sustainable Urban Drainage Systems (SUDS) (Fletcher et al. 2015), such as green channels and discharged roofs, is proposed as a viable alternative to mitigate the effects of flooding in consolidated sectors of the city of Tunja, particularly those operating under a combined sewer system (Guptha et al. 2022). These solutions were selected for their proven effectiveness in controlling surface runoff in urbanized areas with low natural infiltration capacity (McClymont et al. 2020; Zahabkar et al. 2023), and for their adaptability to consolidated urban contexts, such as the Caminos de Oriente neighborhood, where there are spatial limitations that hinder the implementation of larger-scale solutions.

The hydraulic model made it possible to integrate these sustainable alternatives and evaluate their effect on flood risk reduction, providing relevant inputs for decision-making in the design of infrastructures that consider the expansion of green areas and the redistribution of collectors. In this context, green channels stand out as an economically and technically viable option. Their main function is to capture and slow down runoff, increasing the water concentration time and facilitating its infiltration into the soil (D'Ambrosio et al. 2023). When integrated into the design of the public space, these channels not only contribute to reducing the volumes and velocities of surface runoff, but also improve the hydraulic behavior of the area and reduce critical flooding points (Green et al. 2021).

On the other hand, discharged roofs represent an effective solution for highly urbanized areas where it is not feasible to build green channels due to space restrictions or existing infrastructure. This system captures rainwater from residential roofs and gutters and redirects it to gardens or permeable green areas, which promotes infiltration and reduces runoff volumes that would otherwise be directed to public roads or impervious areas (Boogaard 2022).

Both alternatives are not only technically effective and low-cost, but also allow for progressive and scalable implementation, which is essential in a context of climate change, accelerated urbanization and limited infrastructure. Moreover, their implementation contributes to broader objectives of sustainable urban development, climate adaptation and urban resilience (Pessoa et al. 2024).

Tables 2–4 show the consecutive hours with the highest precipitation, in which the periods of 1, 3, and 6 h are listed with their respective percentages. Due to the slight variation between the periods, it can be concluded that the three types of storms occur with equal frequency in the city. Therefore, the three storm durations for the Tunja case study were analyzed for different total precipitation values according to the climate change analysis.

With the values of a 5-year return period of the IDF curves, the intensity values expressed every 15 min in a total interval of 6 h were obtained. A linear interpolation was performed for the values of the intervals in which there are no records, and the total precipitation value in each interval was calculated, as shown in Table 1. Likewise, the values obtained by adjusting the maximum historical rainfall value in 20 years are presented, which gives a total precipitation value of 56.4 mm.

Figure 2 shows the values and the hietograms obtained from the 14% adjustment to the 56.4 mm of rainfall from the first step, according to the global climate change scenarios established by the IDEAM (IDEAM 2021) and the information provided by the Reglamento Técnico Del Sector de Agua Potable y Saneamiento Básico (RAS) (2016), thus obtaining the values for the first, second and third rainfall scenarios. Additionally, the distribution is presented by the method of Alternate Blocks for the precipitation intensity recorded every 15 min.

Therefore, the 64.3 mm value should be interpreted as a conservative estimate and not as data derived directly from an analysis of hourly frequencies. It is included as a hypothetical critical scenario, in order to evaluate the resilience of the system to plausible extreme events.

As the adjusted precipitation value will be 64.3 mm, according to the 14% adjustment for the effect of global warming, it will be distributed in such a way that three different scenarios will be presented, the first with a value of 64.3 mm precipitation for a 6-h storm (Table 2), the second with the same precipitation value, but for a 3-h storm (Table 3) and the third with the same precipitation value for a single storm (Table 4). Figure 2 summarizes the three hietograms for the three scenarios.

Figure 3 shows the system's behavior under the first scenario. The values called ‘Link Capacity’ of 0.25, 0.70, 0.85, and 1 correspond to the hydraulic depth of the pipes. The Colombian normative (Reglamento Técnico Del Sector de Agua Potable y Saneamiento Básico (RAS) 2016) allows a maximum link capacity of 0.85. Similarly, the capacity of the ‘Node flooding’ wells is represented by colors, with red as the limit value corresponding to 100% of the well capacity. The system's pipes do not comply with the normative parameters of the RAS regarding the hydraulic depth of the collectors, and in certain wells the total capacity of 100% is exceeded, which is associated with flooding in the area.

This shows that the system is composed of old networks, and some of the new proposed networks cannot withstand the characteristics of the first precipitation scenario. The saturation of wells and pipes would produce a runoff flow through the streets of approximately 1,990 m³.

In the second scenario (Figure 4), which corresponds to the same amount of rainfall in less time, it is observed that the hydraulic depth of the pipes is increasing, as well as the maximum capacity of the greater number of wells than in the previous scenario. Approximately a flow of 8,721 m³ is produced, corresponding to the flow that would overflow the system due to the saturation of wells and pipes.

In the strongest scenario (Figure 5), it is observed that the hydraulic depth of 28 sections is above 85%, which means that flooding will occur at different points in the district for that rainfall scenario. In addition, when the pipes and wells are saturated, they produce a flow of approximately 19,000 m³, corresponding to the flow that overflows from the pluvial system and through the streets.

In general, the analysis of the three rainfall scenarios reveals a progressively more critical behavior of the urban drainage system in the face of adverse weather conditions. In the first scenario, with moderate rainfall, there is already evidence of saturation of several wells and sections of the network that exceed the hydraulic capacity limit allowed by the Technical Regulations of the Drinking Water and Basic Sanitation Sector (Ministerio de Vivienda 2016), indicating an ageing and undersized system. The estimated surface runoff of 1,990 m³ suggests that even events of intermediate intensity can produce significant local flooding.

This type of behavior has been observed in other Latin American cities. For example, a study in Santa Clara, Cuba showed that old networks without proper maintenance present critical points of water accumulation that require complementary structural and non-structural measures in order to enhance their positive effect on the resilience of the urban system to intense rainfall events (Castillo García et al. 2022).

The second scenario, which simulates the same amount of rainfall in a shorter time interval, considerably increases the pressure on the system. The hydraulic depth in the pipes increases and a greater number of wells reach their maximum capacity, which generates a runoff close to 8,721 m³. This significant increase reflects typical behavior in urban systems vulnerable to climate change. In the southeastern sector of the city of Tunja, it was shown that scenarios of higher rainfall intensity drastically increase the hydraulic load and flooding potential, which evidences the need to implement SUDS as a mitigation strategy.

According to a recent study, climate change and continued urban population growth call for an urgent response to stormwater management issues. One of the most promising options is nature-based solutions (NBS), in which SUDS play a central role. These sustainable technologies – such as green roofs, rain gardens, filter strips, vegetated gutters, artificial wetlands, and permeable pavements – manage water through retention, infiltration, and evapotranspiration (Kõiv-Vainik et al. 2022).

Although results on retention capacity vary according to climate and type of SUDS, evidence shows that their implementation contributes significantly to mitigate the effects of extreme rainfall. In particular, green roofs show a mean retention capacity of 56% (±20%), although with variability between 11 and 99%. This reinforces the importance of integrating SUDS into urban planning as an adaptive measure in the face of increased rainfall frequency and intensity, thus favoring more resilient runoff management in urban scenarios affected by climate change.

Along the same lines, a study conducted in Milan, Italy, analyzed the performance of SUDS under extreme precipitation conditions, both observed and projected, and evidenced that although they are effective flood control measures, their performance may decrease with increasing rainfall severity and intensity as a result of climate change. The study proposed a Precipitation Variability Adaptation Index (PVAI) to evaluate this capacity, concluding that SUDS should be designed considering future climate scenarios, since their effectiveness may be significantly affected if they are designed based only on historical data (D'Ambrosio et al. 2023), thus presenting another challenge to the management of hydraulic systems.

The third scenario represents an extreme event in which 28 sections of pipe exceeded 85% of their capacity, generating an estimated runoff of 19,000 m³. This result shows a generalized failure of the drainage system in the face of extraordinary events, which coincides with experiences reported in other cities around the world. In the city of Gurugram, India, obsolete hydraulic infrastructure and poor maintenance management have contributed to the intensification of flooding events, a phenomenon that is aggravated by the increase in torrential rains associated with climate change (Guptha et al. 2021). This scenario highlights the need to strengthen monitoring and analysis capabilities through advanced technologies. In particular, remote sensing is presented as a key tool to overcome the scarcity of high-resolution terrestrial data, a common limitation in developing countries, where access to conventional monitoring networks is restricted.

In this context, it is imperative to implement multiple tools for the acquisition, processing and validation of hydrometeorological data, which allow the construction of reliable and updated sources of information. These inputs are essential to improve hydrological and hydraulic modeling processes, as well as to support decisions on design, planning and construction of infrastructure that is more resilient to extreme events.

The performance of these scenarios is projectable to other urban contexts where extreme weather conditions, such as sea level rise, heat waves, heavy rains or hurricanes, significantly affect urban infrastructure throughout its lifespan. A comparative analysis of multiple case studies confirms that the cumulative impacts of climate change on cities require adaptive, multi-sectoral and long-term solutions based on the integration of resilient strategies from urban planning to operational water resource management (Mishra & Sadhu 2023).

For example, a national study in Japan analyzed the impact of different climate scenarios based on representative concentration pathways (RCPs) on the expected annual cost of flood damages. The results indicated that, without mitigation measures, the cost may double or even triple by the end of the 21st century. The results of the study showed that, without mitigation measures, the cost of flood damages could double or even triple by the end of the 21st century (Yanagihara et al. 2022).

Consequently, the multifactorial climate crisis calls for a comprehensive, urgent and forward-looking approach. Cities must prepare not only to withstand current extreme events, but also to adapt to changing and increasingly uncertain climate scenarios. Efficient urban water management becomes a fundamental pillar of this adaptation. The implementation of NBS, such as SUDS, the modernization of water infrastructure, and the integration of advanced climate monitoring and modeling tools are key to optimizing urban resilience.

To mitigate the effect of flooding, it is proposed to consider the hourly intensity for the design of new collectors. In this case, the value of 64 mm/h corresponds to the maximum intensity recorded during the observed extreme event and is used as a reference for design. Unfortunately, the available hourly pluviometric information is scarce, so it is recommended that estimates and approximations of hourly rainfall intensities be made using various hydrological methods proposed in the literature. These considerations should be integrated into the design of higher-capacity collectors, capable of responding to such extreme precipitation scenarios. Figure 6 illustrates the location of the SUDS in the Caminos de Oriente district and the hydraulic behavior of the area with the implementation of SUDS under the third precipitation scenario. In this case, the SUDS include poured covers and green channels, which contribute to mitigate the impact of heavy rainfall.

A comparison of Figures 5 and 6 shows that the SUDS act as runoff flow retainers, significantly reducing the points at risk of flooding. It is important to note that only two SUDS alternatives were implemented; however, if more sustainable drainage solutions were implemented, the positive results could be increased.

The results of this paper show that combining SUDS with land leveling can enhance water retention, thereby reducing flood intensity by accelerating flow toward drainage nodes. Urban design should carefully address slope management during pipe installation. Additionally, future urban projects must account for climate change and increased precipitation to ensure infrastructure sustainability. The present modeling and many publications have shown that green spaces, beyond their environmental benefits, play a crucial role in flood control, especially in cities with high flood risk. Authorities responsible for risk management should prioritize data availability to create effective alarm systems based on precipitation and node discharge capacity.

This research modeled the behavior of the urban drainage system in a sector of the city of Tunja that is highly exposed to the risk of flooding due to the limited hydraulic capacity of the existing infrastructure. Through the simulation of three storm scenarios, which incorporate variations in the intensity and duration of precipitation under current and projected climate change conditions, a clear tendency for the system to collapse in the face of extreme events was identified. In all cases, the system responded poorly, evidencing its lack of preparedness for more frequent and intense rainfall scenarios.

The implementation of SUDS was presented as an effective mitigation measure, achieving a significant reduction in the volume of surface runoff. These systems, by retaining and slowing down the flow of rainfall, reduce the pressure on the sewerage network, helping to prevent its collapse. Elements such as green roofs and infiltration channels demonstrated a positive impact on reducing flood risk, highlighting the potential of NBS to complement traditional gray infrastructure.

The results obtained show that the current drainage system is not only insufficient for the current climatic conditions but will be even more vulnerable in the face of climate change projections. This situation responds to a widespread problem in which the hydraulic infrastructure has been designed based on historical parameters that do not take into account either hourly precipitation intensities or climate change scenarios. Therefore, an urban adaptation strategy that includes three key components is indispensable: (i) the modernization of existing drainage networks, (ii) the integration of sustainable technologies such as SUDS, and (iii) a more integrated water management that promotes the collection, storage and reuse of rainwater.

In this context, the prospective and resilient design of urban infrastructure presents itself as an important alternative. To achieve this, planners must rethink the traditional planning process, incorporating a climate risk approach from the earliest stages of urban design. This implies moving away from projections based solely on historical data and adopting predictive models that integrate future climate scenarios, maximum precipitation intensities and sustainable solutions. In addition, greater articulation is required between land use planning, water resource management and urban adaptation strategies, ensuring that decisions are based on scientific evidence and sustainability criteria.

Finally, it is proposed to expand the scope of this type of modeling to other strategic sectors of Tunja and replicate the methodology in other cities with similar characteristics. This technical information represents a valuable input for decision makers in urban planning and climate risk management, contributing to the formulation of public policies that promote safer and more sustainable territories adapted to future conditions.

The authors thank the company Veolia Aguas de Tunja, where the internship and research were conducted, whose results were an important input for the development of this article. The previous results from the internship were published in 2017 (Daza & Lesmes Fabián 2017).

The publication of this research was funded by the Universidad Pedagógica y Tecnológica de Colombia, Sede Tunja.

C.M.D. and C.L.F. conceptualized the study; J.A.S. wrote, reviewed, and edited the article; J.A.S. acquired funds for publication.

All relevant data are included within the article.

The authors declare there is no conflict.