Biophysical landscapes of the Río La Virgen watershed in the Ocosingo municipality, Chiapas, Mexico

ABSTRACT

The Río La Virgen watershed is located in the northwestern end of the municipality of Ocosingo, Chiapas, Mexico. This hydrographical unit is home to the city of Ocosingo. The objective of this research was to characterize the Biophysical landscapes that constitute the basin at the scale of 1:50 000. To achieve this goal, data on the biophysical components was compiled.

This research defined five taxonomic typological levels: 3 classes, 10 subclasses, 22 localities, 52 land areas, and 213 sub-land areas. The main differentiating factors of the landscapes are the tectonics processes, which generate tectonic-karstic and tectonic-accumulative mountains; however, the inventory also reports landscapes of fluvio-torrential and fluvio-accumulative origin in temperate humid, semi-warm humid, and warm humid climates. The landscapes of tectonic-karstic and tectonic-accumulative origin cover over 85.42% of the surface area of the basin; by contrast, the Biophysical Landscapes of fluvial-accumulative and fluvial-torrential cover only 14.85%.

KEYWORDS:

• Biophysical landscape
• tectonic-karstic
• tectonic-accumulative
• river watershed
• Chiapas
• Mexico

1. Introduction

The latest global trends on territorial planning point out that the geographical approaches based on the concept of landscape are an alternative to territorial management since they analyze biophysical and socio-economic systems in a holistic and integrated manner (Miklós et al., 2019; Simensen et al., 2018).

In this context, complex physical geography is an option for planning instruments, because it establishes an objective zoning of space based on the structural-genetic and historical-evolutionary principles of the geosphere (Mateo, 1984; 2002; Priego Santander et al., 2004). This branch of geography, developed in Eastern Europe and applied in Latin America including Mexico (Bollo Manent, 2018; Solodyankina et al., 2021; Morales-Iglesias et al., 2022; Bollo-Manent & Martínez-Serrano, 2023), defines the Biophysical Landscape (BL) or geosystem as a territorial system consisting of natural elements, which are transformed by human society in a historical context (Mateo, 1984; 2002). In this approach, the geological, geomorphological, and climate components play a leading role in the structure and functions of the BL, because they determine the distribution of soil and vegetation cover (Priego Santander et al., 2004).

This research aims to know the structure of the BL that comprises the study zone at the scale of 1:50 000 (see map). To achieve this, five taxonomic levels – Class, Subclass, Locality, Land areas, and Sub-land areas (Campos-Sánchez & Priego-Santander, 2011; Ramírez-Sánchez et al., 2019), were determined through a series of map overlays (see Table 1).

Table 1. Diagnostic indices of the Biophysical landscapes (Modified from Campos-Sánchez & Priego-Santander, 2011; Ramírez-Sánchez et al., 2019; Morales Iglesias et al., 2017).

Taxonomic level	Definition	Diagnostic indices	Example
Class (1)	(1) is composed of Subclasses, Localities, Land areas, and Sub-land areas. Its genesis is heterogeneous, but it has the same climate.	Morphostructures of heterogeneous genesis in the same climatic condition.	A. Mountains, hills, foothills, and plains in temperate climate. (1) Uses a capital letter.
Subclass (2)	(2) is formed by Localities, Land areas, and Sub-land areas.	Specific type of relief with a heterogeneous origin in the same climatic condition.	A.1. Mountains in temperate climate. (2) Uses a capital letter followed by an Arabic number.
Locality (3)	(3) is formed by land areas and sub-land areas.	Mesoform with the same morphogenetic type of relief; lithological or deposits homogeneity; similar climate regime with the same biocenosis and soil types.	I. Tectonic-karstic mountains, from moderately dissected (DV = 100-500 m/km²), formed by limestone-dolomite, in temperate humid climate, with secondary vegetation and crops, on Leptosol and Luvisol. (3) Uses a roman number.
Land area (4)	(4) Is a level of landscape structure, formed by sub-land areas and facies.	Associations of the same morphologic set on a mesoform of relief; predominance of a similar set of vegetation cover, land uses, and soils.	I.1. Complex of peaks, with secondary vegetation, on Leptosol and Luvisol. (4) Uses a Roman number followed by an Arabic number.
Sub-land area (5)	(5) structure of one level, formed by facies	Is a unit located on a single mesoform of relief with similar slope inclination; the same type of vegetation cover and land use; similar soil types and subtypes.	1. Medium to strongly inclined peaks (15°−20°), with shrubby secondary vegetation of oak-pine forest, on lithic and rendzic Leptosols and chromic Luvisols. (5) uses an Arabic number

2. Study area

The watershed Río La Virgen is located in the northwestern end of the municipality of Ocosingo, Chiapas, Mexico; its coordinates are from 16° 44’ 59” to 17° 0’ 06” N and from 92° 14’ 48” to 92° 15’ 50 W. This hydrographical unit covers 306 km² and has a wide altitudinal range, with its highest altitudinal terrain at nearly 1,980 masl, and its lowest at 800 masl.

The study area is located in the subprovince Sierras del Norte de Chiapas, belonging to the physical-geographical province Sierras de Chiapas y Guatemala; this region is formed by medium – and low-altitude mountains (DV < 500 m/km²) and hills, blocky in folds and monoclines, deformed by transcurrent tectonic stresses, with rocks of the Mesozoic and Tertiary folded sedimentary complexes (folded, subhorizontal and inclined, undifferentiated sediments), in semi-warm humid and warm humid climates (Bollo Manent et al., 2015).

This study area includes Ocosingo City, which is the largest city in the region. It has a population of 47,688 people with high levels of marginalization (Instituto Nacional de Estadística y Geografía, 2020). This city is connected via strong land connections known as The Ruta Maya with the major tourist spots in the North and East of the Chiapas State. Its natural landscapes and archaeological sites make this region a popular tourist destination (Garza Tovar et al., 2020). This circuit crosses the middle basin on a North–South course.

3. Method

This research defined five taxonomic typological levels: Class, Subclass, Localities, Land areas, and Sub-land areas at a scale 1: 50 000 (Table 1) (Priego Santander & Bocco, y Garrido, 2010; Campos-Sánchez & Priego-Santander, 2011; Ramírez Sánchez et al., 2012; Morales Iglesias et al., 2017).

Classes and subclasses are regional units that only head the legend of the 1:50 000 maps but are not directly represented on the map. Localities are expressed through colors and Roman numerals; land areas are identified with a Roman numeral followed by a point and a natural number and are indirectly represented on the map through the lower units (sub-land areas). Sub-land areas are represented on the map by successive natural numbers (Priego Santander & Bocco, y Garrido, 2010).

To achieve this goal, this study was carried out in three stages, which are described below (Figure 1).

Figure 1. Methodological steps for the elaboration of the Biophysical Landscape map.

Dear Editor, The main map should be at: Descrption of the landscape units.

Stage 1. Biblio-cartographic review.

In this phase, a biblio-cartographic compilation and a cartographic standardization regarding cartographic parameters (coordinate system and projection) of the biophysical components were carried out (Table 2).

Table 2. Cartographic references used to generate the Biophysical Landscapes map (Modified from Ramírez-Sánchez et al., 2019).

Input map	Source	Format	Scale
Contour lines map	INEGI (2015)	Vectorial/shapefile	1:50 000
Digital Elevation Model (DEM) cell resolution: 15 m.	INEGI ( 2013)	Raster	1:50 000
Vertical Dissection	Own elaboration from the contour lines map	Vectorial/shapefile	1:50 000
Geology	Servicio Geológico Mexicano (2019)	Vectorial/shapefile	1:50 000
Climate	Own elaboration based on Garcia's proposal (2004).	Vectorial/shapefile	1:50 000
Slope	Own elaboration from the contour lines map	Vectorial/shapefile	1:50 000
Vegetation and land use	Own elaboration based on Lao & Peláez’s proposal (2018) with satellite image LANDSAT Cell resolution 15 m ).	Vectorial/shapefile	1:50 000
Soil	INEGI (2007)	Vectorial/shapefile	1:250 000

Stage 2. Biophysical characterization.

The first step of this phase was to morphometrically zone the territory through vertical dissection based on Lugo-Hubp’s (1988) and Priego Santander and Bocco, y Garrido (2010); then, the climate component was characterized using Garcia’s proposal (2004); and finally, the vegetation types and land use were identified by using the method proposed by Lao and Peláez (2018).

To obtain coherence in the spatial representation, a conceptual and spatial generalization was applied to each component (Priego Santander & Bocco, y Garrido, 2010).

Stage 3. Integration of the biophysical components to elaborate the BL map.

This stage included several steps:

1. an overlay of the vertical dissection information and the lithological map (Servicio Geológico Mexicano, 2019) to obtain a morpho-lithologic map.

2. A cartographic overlapping of the previous result with the climatic map to obtain a morpho-litho-climatic map or localities map;

3. A cartographic overlapping of this map with the relief units that compose the mesoform (complex of summits, hillslopes and gullies, surfaces and streams), to identify the BL at the Land area level.

4. A cartographic overlapping of the result of step 3 with the slope map to obtain sub-land area units.

5. A cartographic overlapping of the vegetation and land use with the result of step 4.

6. The same cartographic procedure to incorporate soil information (Instituto Nacional de Estadística y Geografía, 2007) to the sub-land area units.

7. A series of cartographic corrections based on information obtained and verified in the field.

This process generated a series of arrangements in the geometry of the polygons. Table 3 summarizes the steps performed to obtain the BL map.

Table 3. Methodological processes to obtain the BL map (Modified from Morales-Iglesias et al., 2017 & Ramírez-Sánchez et al., 2019).

Step	Procedure	Result
I	Cartographic overlap of the vertical dissection map with the lithological information.	Morphogenetic map.
II	Cartographic overlap of the climatic map with the result of step I	Landscapes map at the localities level.
III	Union of the result of step II with secondary geoforms or inferior units.	Landscapes map at land area level.
IV	Union of the result of step III with the slope map.	Landscapes map at sub-land area level.
V and VI	Cartographic overlap of the result of step IV with vegetation, land use, and soil information	Cartographic hypothesis.
VII	Field verification	BL map with three levels (localities, land areas, and sub-land areas)

4. Description of the landscape units

According to the results, the watershed has 3 classes, 10 subclasses, 22 localities, 52 land areas, and 213 sub-land areas (Table 4). In this case, tectonic processes are the main drivers of the BL differentiation, which are represented by climatic zones. Although the map legend is explicit and explanatory regarding the composition and structure of the geosystems, the five main landscapes or localities covering 57% of the total surface area are briefly discussed below (Figure 2) (Main Map):

Figure 2. Area of the Biophysical Landscapes at the locality level.

This figure shows the area occupied by the localities in the basin.

Table 4. Taxonomic levels of the biophysical landscapes.

1. Class	2. Subclass	3. Locality	4. Land areas	5. Sub-land areas
A. Mountains, Hills, Foothills, and Plains in temperate climates.	A.1. Mountains in temperate climates.	I	I.1. / I.2. / I.3.	1 - 12
B. Mountains, Hills, Foothills, and Plains in semi-warm climate.	B.1. Mountains in semi-warm climate.	II	II.1. / II.2. / II.3.	13 −22
		III	III.1. / III.2. / III.3.	23 - 36
		IV	IV.1. / IV.2. / IV.3.	37 - 55
		V	V.1. / V.2. / V.3.	56 - 66
		VI	VI.1. / VI.2. / VI.3.	67 - 79
	B.2. Hills in semi-warm climate.	VII	VII.1. / VII.2. / VII.3.	80 - 91
		VIII	VIII.1. / VIII.2. / VII.3.	92 - 102
	B.3. Foothills in semi-warm climate.	IX	IX.1. / IX.2.	103 - 110
		X	X.1. / X.2.	111 - 117
	B.4 Plains in semi-warm climate.	XI	XI.1.	118 - 123
C. Mountains, Hills, Foothills, Valleys, and Plains in warm climate.	C.1. Mountains in warm climate.	XII	XII.1. / XII.2.	124 - 129
		XIII	XIII.1.	130 - 131
		XIV	XIV.1.	131 - 136
	C.2. Hills in warm climate.	XV	XV.1. / XV.2. / XV.3.	137 - 147
		XVI	XVI.1. / XVI.2. / XVI.3.	148 - 157
		XVII	XVII.1. / XVII.2. / XVII.3.	168 - 169
		XVIII	XVIII.1. / XVIII.2. / XVIII.3.	170 - 185
	C.3. Foothills in warm climate.	XIX	XIX.1. / XIX.2. / XIX.3.	186 - 195
	C.4. Valleys in warm climate.	XX	XX.1. / XX.2.	196 - 202
	C.5. Plains in warm climate.	XXI	XXI.1.	203 - 209
		XXII	XXII.1.	209 - 213

Landscape IV: Tectonic-karstic mountains, slightly to moderately dissected (VD = 100–500 m/km²), formed by limestone-dolomite, in semi-warm humid climate, with secondary vegetation and crops, on Leptosol, Luvisol, and Phaeozem. This kind of landscape is comprised of 3 land areas and 19 sub-land areas that are distributed in the west, south, and northwest in the watershed, and cover 18.40% of the study area. This geosystem is integrated by a complex of summits, hillslopes and gullies, surfaces, and streams. There are several soil types such as Leptosol, Luvisol, and Phaeozem, and the main vegetation is secondary vegetation and crops (Figure 3).

Figure 3. Photo of the western part of the basin taken on December 1, 2022. Locality IV is in the background; (a) Ocosingo city.

Figure 3 shows the locality IV and Ocosingo city.

Landscape XXI: Tectonic-accumulative acolinate plains, medium to strongly dissected (VD = 20–40 m/km²), formed by silt-sand, in warm humid climate, with grasslands, on Luvisol and Phaeozem. This landscape comprises one land area and seven sub-land areas, located in the center, east, and south of the watershed; these units cover 11.75% of the study area. This BL is constituted by complex surfaces and streams. There are two soil types, Luvisol and Phaeozem, which support secondary vegetation, grassland, and crops (Figure 4).

Figure 4. Photo of the southern part of the basin taken on December 3, 2022. Locality XXI is in the foreground.

Figure 4 shows the locality XXI.

Landscape VII. Tectonic-karstic hills, strongly dissected (DV = 80–100 m/km²), formed by limestone-sandstone, in semi-warm humid climate, with secondary vegetation and crops, on Luvisol, Regosol and Phaeozem. The landscape is constituted of three land areas and 12 sub-land areas, located in a corridor shape in the northwest, south, and east-central, covering 10.20% of the watershed. This BL comprises a complex of summits, hillslopes and gullies, surfaces, and streams; over this geomorphologic condition, there are Luvisol, Regosol, and Phaeozem soils, which support secondary vegetation, grassland, and crops (Figure 5).

Figure 5. Photo of the southern part of the basin taken on December 4, 2022. Locality VII is in the foreground.

Figure 5 shows the locality VII.

Landscape XIX. Fluvial-torrential foothills, formed by sandstone-lutite and silt-sand, in warm humid climate, with grasslands, on Luvisol, Phaeozem and Regosol. This landscape is constituted by three land areas and ten sub-land areas, which are located in a corridor shape in central, south, and northwest, and cover 7.8% of the watershed. This landscape comprises a complex of residual hills, interfluve, and distributary streams, surfaces, and streams; over this relief, there are Luvisol, Regosol, and Phaeozem soils, which support grassland and secondary vegetation (Figure 6).

Figure 6. Photo of the northern part of the basin taken on December 4, 2022. Locality XIX is in the background.

Figure 6 shows the locality XIX.

Landscape III. Tectonic-accumulative mountains, moderately dissected (VD = 250–500 m/km²), formed by sandstone-lutite, in semi-warm humid climate, with secondary vegetation and crops, on Luvisol, Leptosol and Regosol. This landscape is composed of 3 land areas and 14 sub-land areas, which are located in the northwest in a corridor shape that covers 7.4% of the study zone. This BL comprises a complex of summits, hillslopes and gullies, surfaces, and streams; over this relief, there are Luvisol, Leptosol, and Regosol, which support secondary vegetation and crops (Figure 7).

Figure 7. Photo of the northwestern part of the basin taken on December 06 2022. Locality III is in the foreground.

Figure 7 shows the locality III.

5. Conclusions

The geoecological approach permitted the division of the study area into five taxonomic levels at scale 1:50 000.

The BL typology comprises 3 classes, 10 subclasses, 22 localities, 52 land areas, and 213 sub-land areas.

In the study area, the tectonic processes are the main factor of landscape differentiation; therefore, the BL of tectonic-karstic and tectonic-accumulative origin in semi-warm humid and warm humid climates exert a territorial predominance.

The applied method allowed the zonation of the territory logically and hierarchically. The cartographic hypothesis showed a correspondence with the field observations.

The obtained BL map can be applied to environmental assessment and territorial planning.

Finally, this research is a contribution to the geographical knowledge of a region that has a high natural heritage in Chiapas, Mexico.

Software and data

The spatial data were standardized, integrated, processed, and edited through the geographic information system ArcGIS 10.8 (ESRI, 2020). In the first stage, we applied the Projections and Transformation tool from the Data Management Tools module. In the second phase, we used the Data View module and the Add tool. In the next stage, we employed Intersect, Dissolve, and Eliminate tools for the vector data, and in the case of the raster data, we used the following tools from the Spatial Analyst module: Density, Neighbourhood, and Reclass. In the last phase, we utilized all tools that integrate the View and Insert modules. The working environment and cartographic edition were made at scale 1:50 000 (Table 5).

Table 5. Description of the geoprocessing tools used in ArcGIS 10.8 (ESRI, 2021).

Number	Format	Tools	Description
1	Vector	Intersect	Calculates a geometric intersection of the input entities
2		Dissolve	Aggregates entities based on specified attributes
3		Eliminate	Eliminates polygons by merging them with neighbor polygons that have the largest area or the longest shared border.
4	Raster	Density	Calculate the density of input features within a neighborhood around each output raster cell.
5		Neighborhood	Calculates for each input cell location a statistic of the values within a specified neighborhood around it.
6		Reclass	Reclassifies (or changes) the values in a raster

Acknowledgements

The authors thank Sandra Urania Moreno Andrade, director of the Instituto de Investigación en Gestión de Riesgos y Cambio Climático of the Universidad de Ciencias y Artes de Chiapas, for supporting the research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data regarding the Biophysical Landscapes at class, subclass, locality, land area, and sub-land area levels are available upon reasonable request to the corresponding author ([email protected]).