Caracterización fisiográfica, para determinar la erodabilidad y su relación con la sequía

meteorológica, en suelos de la finca La Ponderosa, Municipio de Monterrey, Casanare -

Colombia

Article resulting from a research project financed by

the Corporación Universitaria Minuto de Dios- UNIMINUTO

lfigueroa@unbosque.edu.co https://orcid.org/0000-0003-

2326-6904

Javier Leonardo Romero-Fernandez

jlromero@unbosque.edu.co https://orcid.org/0000-0001-

5045-114X

geomorphological and physiographic parameters, especially the slopes present on the

Ponderosa farm, to determine the areas susceptible to erodability. Using GIS - geographic

information system tools, six zones or "paddocks" were determined in which slope ranges

were classified between 0 and 10, with zero being the least and 10 being the greatest. In the

paddocks called 2, 3, 4 and 6, the areas with the highest ranges, between 6 and 10, were

identified, indicating steep to steep slopes, these being the most susceptible to mass

movements, runoff and therefore erodability. These factors identified in the present

investigation, directly influence the sustainability of the productive activities of the farm such

as livestock and in some sections, palm crops.

Keywords: Threat due drought, Erodability, GIS, Sustainability, Casanare.

esta investigación busca relacionar la amenaza por sequía meteorológica con parámetros

geomorfológicos y fisiográficos, en especial las pendientes, presentes en la finca la Ponderosa,

para determinar las zonas susceptibles a erodabilidad. Mediante la utilización de

herramientas de sistemas de información geográfica SIG, se determinaron seis zonas o

“potreros” en los cuales se clasificaron rangos de pendientes entre 0 y 10, siendo cero la

menor y 10 la mayor. En los potreros denominados 2, 3, 4 y 6 se identificaron las zonas con

mayores rangos, entre 6 y 10, indicando pendientes abruptas a escarpadas, siendo estas las

más susceptibles a movimientos en masa, escorrentía y por ende a erodabilidad. Estos

factores identificados en la presente investigación, influyen de manera directa en la

sostenibilidad de las actividades productivas de la finca como lo son la ganadería y en algunos

INTRODUCTION

During the last decade, the drought experienced in the department of Casanare has left about

250,000 hectares of green savannahs full of water and animals, now turned into a desert and

causing the death of different species such as cattle, chigüiros, babillas, fish, etc. (Palacio &

exceeding a level of occurrence of an event with a level of severity at a specific site and during

a period of time; for this reason, in most cases, hazard assessment is carried out by combining

probabilistic analysis with analysis of the physical behavior of the generating source, using

information on events that have occurred in the past and modeling with some degree of

approximation to the physical systems involved (Cardona, 1993).

According to the Colombia Risk Atlas reveals latent disasters that drought originates through

a deficit of rainfall over an extended period of time, resulting in a shortage of water for some

activity or sector. Its impacts are due to the interaction between the natural event (less

rainfall than expected) and the demand for water supply, a situation that in many cases is

exacerbated by human activities.

(Minambiente, 2005). The above, through methods and the use of geographic information

systems where drought can be calculated, allowing the development of more detailed spatial-

temporal analysis in order to define the severity, frequency and distribution of droughts at

different scales, where exposure and vulnerability are integrated to provide information on

the possible economic, environmental or social consequences generated by drought.

The urgency that has arisen at the national level and mainly in the department of Casanare to

provide alternatives that help mitigate the negative effects that originate at the

environmental, social and economic level in relation to drought in this territory cannot be

ignored. In this sense, the present project is proposed through the use of different tools,

among them the GIS that allow identifying the diverse impacts that are generated in the soil

geological, geomorphological and physiographic analyses, with the purpose of designing

Monterrey, Casanare.

MATERIALS AND METHODS

For the development of this research, a bibliographic review was carried out, with which

international, national and local references were analyzed. Thanks to these theoretical

references, the research was delimited and focused in order to comply with the objectives

set out in the research. Through the studies entitled "General Study of Soils and Land Zoning

in the Department of Casanare" (IGAC, 2014) and "Annexes of the Explanatory Memory of the

Zoning of the Susceptibility and Relative Threat by Movements in Mass scale 1:100.000 plate

230 - Monterrey" (SGC, 2013), the physiographic aspects were determined, including the

format, then the Spatial Analyst Tools tool was used, then the Surface window and finally by

clicking on the Slope window.

Finally, for the geographic characterization, the respective visit was made to analyze the

topography of the terrain to obtain information on its condition. According to the information

obtained, the current state of the study area was represented by means of the free software

Google Earth.

RESULTS

In order to obtain the results, the study conducted by the IGAC (2014) entitled "General Study

of Soils and Land Zoning, Department of Casanare. Scale 1:100,000", identifying the

Physiographic and Geographic Characteristics

1. Location. The representative area for the present study was the La Ponderosa farm, which

is located southwest of the municipality of Monterrey - Casanare, on the foothills of the

plains, in the Tierra Grata district, 11 kilometers from the urban center, at the coordinates 4

eastern plains.

Based on the above information, in the geological aspect of the study area, a lithological

environment of shallow waters. Its outcrop is located in small strips in the divisions of the Túa

river.

- Une Formation. It is made up of three groups: a basal group that consists of solid quartz

sandstone of white color and fine to medium grain; towards the middle part, the sandstone

becomes conglomeratic and towards the top there is clayey sandstone of reddish color and

fine to medium grain. The middle group is made up of dark gray mudstones, with thin

intercalations of quartz sandstone, reddish in color, fine grained, well sorted and in strata up

to 1 m. And an upper group, made up of white quartz sandstone, fine to medium grained,

with quartz pebbles up to 5 cm in diameter. The sedimentation environment of the formation

corresponds to a coastal environment with deltaic influence, which is why it resembles the

to marine lagoon environment, outcropping in the form of elongated strips in the upper part

of the Rio Túa basin.

Quaternary

- Colluvial-alluvial deposits. Corresponds to sedimentation units that form colluvial-alluvial

cones, terraces and piedmont alluvial fans, which are predominantly made up of sandstone

blocks and pebbles in a matrix that varies from sandy to clast-supported, sometimes with

lenticular intercalations of sandstones and reddish siltstones. These deposits of colluvial,

colluvio-alluvial, alluvial and/or alluvial-torrential origin are quite dissected and in some cases

tilted by the active tectonics of the region. This type of sedimentation is found in large

proportions throughout the La Ponderosa farm, mainly along the banks of the El Tigre and

rounded cobbles, with block sizes up to gravel; layers of very coarse-grained sands; and fine

materials such as silts and clays in the floodplains. According to SGC (2009) the most

representative alluvial deposits are found in the project study area.

Geomorphology

materials transported from the higher elevations to the lower, more open areas. It comprises

flat, gently sloping surfaces with gradients between 3% and 12%. The piedmont deposits

generally constitute the record of alluvial and alluvial-torrential events that descend from the

mountain range towards the Orinoco plain.

5. Delimitation Through the respective field visit and analysis using the free software Google

Earth, the area of the La ponderosa farm was delimited (Figure 2), which is defined by two

rivers, which are the El Tigre stream located to the west and the Ranchería Creek to the east

of the farm. These two streams belong to the Túa River basin.

Equine and bovine.

The respective field visit showed that this river has a large extension of gallery forest on the

banks of its course. On the other hand, the pastures of Finca La Ponderosa are divided by a

creek that originates from the El Tigre River, where it was identified that this creek produces

3, determining that the reddish and orange shades reflect slope ranges between 6 and 10,

which indicate that they are steep slopes (classification 4) to steep (classification 5) being

more susceptible to mass movements and dragging of material (SGC, 2015), these are located

mainly on the banks of the Tigre River, the Ranchería Creek, in paddocks 2, 3, 4 and 6.