A cause and effect analysis was done to identify the reasons behind landslides in Trinidad along with recommendations and an action plan to assist with remedying their frequent occurrences. To summarize the cause and effects a fishbone diagram was attached to this blog to make this illustration clearer.
A landslide is the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of “mass wasting,” which denotes any down-slope movement of soil and rock under the direct influence of gravity. Landslides involve four types of slope movement which are: flows, falls, topples, slides and spreads.
Landslides have multiple causes for which have been detailed below categorized under the 6 ‘M’ model (Machines, Manpower (people), Materials, Methods, Mother Nature and Management).
Human interaction is a contributing factor in the occurrences of landslides which is not a surprising reality. Humans possess the innate nature to probe and try to improve anything that shows the need to be revolutionized and land is no exception. Some of the human activities that cause landslides are:
Deforestation, which is where people permanently remove trees/forests by burning or cutting them down for various reasons such as:
- To make more land available for housing and urbanization
- To harvest timber to create commercial items such as paper, furniture and homes
- To create ingredients that are highly prized consumer items, such as the oil from palm trees
- To create room for cattle ranching
- To be used as fuel
Tree roots are anchors and when they are removed it causes the soil to be free to wash or blow away, which can lead to landslides.
The building of roads and structures without adequate grading of slopes, or poorly planned alteration of drainage patterns. According to a study done by Southern Tier Central Regional Planning and Development Board, in addition to landslides other potential consequences can include:
Creation of hazards: potential for roads and driveways to wash out leaving a lack of emergency vehicle access and increased car accidents.
Damage to property: they damage homes and property and soil/mud/sediments can destroy downhill property contributing to the instability of streams and resulting in stream-bank erosion damage.
Cause water pollution: transport of polluted runoff due to fewer opportunities for pollutants to settle or be filtered by vegetation can cause septic system failures.
Piggybacking on manpower is the material causes of landslides which is primarily related to the actions or failure to act by humans.
- Poorly built road-ways built as the engineering behind the digging of slopes were initially faulty.
- Structural damage caused by rain and tree removal weakened the very earth allowing movement of the rocks and soil (Nature’s Materials).
- Insufficient upgrades and improvement of structures to ensure the likelihood of a slip is reduced.
To summarize and categorize the potential causes of landslides in order to identify its root cause a fishbone diagram, also called a cause and effect diagram or Ishikawa diagram was used below:
A machine, is a device, having a unique purpose, that enhances or replaces human effort for the accomplishment of physical tasks. This broad category encompasses such simple devices as the inclined, plane, lever, wedge, wheel, axle, pulley, and screw (the so-called simple machines) as well as such complex mechanical systems as the modern automobile. The operation of a machine may involve the transformation of chemical, thermal, electrical, or nuclear energy into mechanical energy, or vice versa, or its function may simply be to modify and transmit forces and motions. All machines have an input, an output, and a transforming or modifying and transmitting device.
All machines are made up of elements or parts and units. Each element is a separate part of the machine and it may have to be designed separately and then assembled. Each element, in turn, can be a complete part or made up of several small pieces which are joined together by riveting, welding etc. Several machine parts are assembled together to form what we call as a complete machine.
As listed above in manpower human interaction is a contributing factor in the occurrences of landslides which is not a surprising reality. The human species possess the innate nature to investigate and attempt to improve anything that shows the need to be revolutionized and land is no exception. Human has always found ways to adapt, evolve and create a mechanism to make everyday life easier from the use of windmills and water channels to generate energy in the implementation of solar powered panels. With manual labor now being a thing of the past so are some of the tools associated with it. We are now in a mechanical and digital era where tools of the past are now obsolete, as much as these present-day machines/tool assist in making the job easier if not used appropriately with discretion they can have a negative effect on our well being.
When accompanied by its human operator machines has been classified as a major contributor to landslides. The inconsiderate work done by contractor to move soil and develop quarries requires the use of heavy machinery excavator and backhoes to be exact when these machinery perform the vibration from such a large vehicle aids in loosening soil in close proximity to where the work is being done also a lot of work is left incomplete by these heavy machinery and these two elements are hazards waiting to happen. At the first sight of rainfall or even unannounced, these landslides occur damaging infrastructure and blocking transit points, worst case scenario taking life.
Another co-contributor would be persons logging and timbering these persons indiscriminately slash and burn our forest with their tools of trade chainsaws, leaving tree stumps in the earth to decay which results with pours in the earth. These pours are easily separated by rainfall or the moving of the earth planes causing these high volumes of debris to come downhill assisted by gravity. With that being said machinery is a moderate contributor to the issue of landslides, not because its contribution to landslides is mediocre it should be ignored.
Lack of landslides monitoring activity
The high severity of damage was chosen as aspect from the major effect heading(Landslides in Trinidad and Tobago) as to better understand how lack of monitoring activities can increase high severity damage of landslides. Activity is very broad and can be broken down to understand the different forms of activity or lack thereof. Non-usage of statistical modelling techniques can exacerbate the high severity of landslides.
The overall risk of high severity damage landscapes can be due to a lack of information about high severity damage as well absence of statistical modelling techniques(Champati ray et al. 2013; Champati ray 2013). Identification of landslide hazard zones or susceptibility mapping which is the study of the likelihood of landslides in particular areas based on its local terrain condition is a good mitigation strategy. A statistical approach can be used to demarcate these particular landslide hazard zones which uses a data driven approach in order to determine ranks or classes within variables based on spatial statistical relationship of landslides(Guri et al,2014). The WoFe method(Weights of Evidence) which is bivariate statistical method, can be used to explain how critical parameters such as geology, slope and land use have an effect on landslides.
With lack of usage of such a statistical technique within Trinidad and Tobago combined with the relevant remote sensing and geographic information system can increase the severity of landslide damage as mentioned earlier. Coupled with climate change, unsound agricultural practices and deforestation presents a need for a such a method as to reduce or at least mitigate the effects of landslides. Increase in extreme rainfall events in Trinidad can be seen to also contribute to landslides, use of these statistical methods here it can better assist in reduction of high landslides severity and also protect people in vulnerable areas.
The category Mother Nature, simply refers to the environmental impacts, or natural causes of landslides in Trinidad. A landslide or landslip is a natural disaster, something which is unfortunately unavoidable. Natural causes of landslides include:
- Erosion. If this occurs, even slightly, it can cause some of the slope to fall into rivers or oceans.
- Earthquakes can also cause the occurrence of landslides. According to the UWI Seismic Research Centre, the countries of the Eastern Caribbean (Trinidad is included here) are highly susceptible to earthquakes. Earthquakes bring about a sharp change in the slope and makes it very unstable.
- Erupting volcanoes can also be a cause of landslides in Trinidad as this can also cause the slope to be unstable.
As aforementioned, there isn’t anything that can be done to avoid the occurrence of landslides in Trinidad, but we can definitely take precaution or put measures in place to safeguard ourselves in the case of any occurring landslides.
The managing authority tasked with the management and coordination of emergency systems of landslides in Trinidad is the Office of Disaster Preparedness and Management (ODPM) according to this eternity “A landslide is the rapid mass movement of soil, mud and/or rocks downhill due to the pull of gravity. Landslides are very common and occur in a variety of forms. Land may topple off in a big chunk, or slip down in bits. Landslide may be composed of mud or may contain rocks and other debris. Most landslides occur gradually, but some may be sudden.” (ODPM, 2013)
An employee from the Ministry of Works and Infrastructure alerts his colleague to falling debris as they attempt to clear a landslide near the lookout along the North Coast Road, Maracas.
Trinidad and Tobago Guardian Newspaper (Jensen La Vende,2017)
Landslides can be caused by man made hazards or natural environmental phenomena such as earthquakes , heavy rainfall on slopes and bad human practices . The cause will determine how the managing authority may target the problem to mitigate against its effects. All man made hazardous acts can be mitigated against at its origin, but environmental hazards are mitigated to reduce its effects as best as humanly possible.
Causes of Land Slides from a Management Perspective-
- Ineffective land management laws due to lack of enforcement.
- Structures and foundations not constructed to building codes, contrary to the Town and Country Planning Act Chapter 35:01 Act 29 of 1960.
- Not controlling the land grabbing of state-owned lands
- Lack of policies in regards to construction on geographically sloped land
- Not understanding the rainfall patterns in relation to the land slide prone areas.
- Limited or no knowledge of citizens on the issue of deforestation practices and wrong agricultural practices and their negative effects that give rise to land slides.
- Lack of proper coordination and cooperation among the agencies, NGOs, community leaders, government, methodological sections and defense force.
- Another issue of proper management concerns the political facet, it is the inability of the government to prepare and coordinate the urban expansion of citizens.
According to Looptt on August 27th 2018 a 6.9 magnitude earthquake occurred and caused this landslide that occurred in Laventille.
The effects of Land Slides-
- Damage to structures and houses.
- Loss of lives
- Damage to infrastructure.
- Blocked roadways
- Landslides that block rivers can cause flash flooding, this occurs when a lake is formed by land slip material blocking the water way. The Lake is eventually breached and gushes downhill to cause flash floods as a result.
The ODPM functions and administrative sections –
- Mitigation and planning which includes the formulating of policy.
- Preparedness Response Unit which deals with coordination of the first respondents.
- Public Information on awareness, dissemination of information, media releases.
- Administrative Support addresses finance, human resources and business services.
- Project Management Unit addresses monitoring of projects, tracking and monitoring of internal and external projects.
Effective Management –
Picture Shows The Land Slide Prone Areas In Trinidad. (ODPM,2013)
The effective management of landslides encompasses a systematic approach which involves the many arms of the government, the ODPM, meteorological departments, NGOs, the defense force and the city corporations. It is also important to consult with representatives from the vulnerable areas to understand the needs of residence. The government authority’s if pivotal in this execution.
The landslide phenomena in Trinidad must be addressed through various channels and at different levels to create a renown impact in its reduction. At an operational standpoint the general public must be sensitized as to the bad practices that contribute to land slides and its alternatives. For example the practice of slash and burn with an alternative of clearing and adding fertilizers to the soil. Additionally, on a legal perspective building codes, land grabbing and illegal lumbering laws should be enforced be the relevant authorities. Politically, governments must have proper communications between the agencies to permit exchange of information and encourage relevant data collection. Economically, money has to be injected in to the projects to ensure proper analysis is done to determine if it would negatively impact landslides. This is done for both private and governmental projects. Socially, the urban overflow must be considered with adequate housing areas allocated for this expansion, diverting housing away from the vulnerable slopes. The implemented measures to curb the negative actions that cause landslides is not limited to those mentioned , but this initiative must be an holistic approach to demonstrate efficiency.
The occurrence of landslides are dependent on various reasons as seen above, however many of these causes can lessen if these hazardous areas are avoided or if activities in such areas are restricted or deployed under certain conditions.
Trinidad’s government is responsible for land-use policies and forming legislation and regulation to reduce the risks associated with landslides. Additionally educating citizens on the history, prevention and causes of these potential disasters could leave a lasting effect on the nation.
Also the use of highly recommended professional services of engineering geologists, civil engineers, or geotechnical engineers, to evaluate the potential of a hazardous site if disrupted can also seek to quell the potential slips.
Other prevention steps could include:
- Avoiding new constructions on steep slopes or by stabilizing the slopes before beginning the actual construction works. When groundwater cannot rise in the landslide mass, stability is increased.
- Covering the land with impermeable membranes in order to prevent water infiltration in the landslide;
- Directing surface water sources away from the landslides prone areas
- Draining groundwater streams
- Minimizing irrigation on the surface of the soil.
- Removal of mass from the top slopes, so that its weight does not force the layer to slide.
Other Recommendations and Mitigating Management Practices–
Managing and coordinating efforts jointly is an important facet to mitigate against landslides by –
- Developing a National Land Use Planning template where high risk slip areas will be flagged and not allowed construction of any sought.
- Developing risk assessments for projects located on slopes and do appropriate feasibility studies to understand the effects and consequences. A cost benefit analysis is needed to weigh the cost of mitigating measures against consequences.
- Risk assessments should be conducted by an independent authority, it is very important as it highlights the consequences to the environment.
- Controlling grabbing of state-owned lands which are more than likely utilized for dwelling house construction.
- Enforcing the laws of Trinidad which states that all buildings must be certified by Town and Country to gain approvals under the Ministry of Housing.
- Developing a landslide data base is important to be able to offer predictions for effective response.
- Systems that can minimize the effects of land slip impacts-
-Implementing Land slide Mapping systems
-Geo physical analysis of the island.
- Sensitizing local residence in the hilly and land slide prone areas on the effects and the knowledge on proper ways to control landslides by introducing proper drainage, soil conservation and proper water shed management to them. This can be done through advisories, media releases and town gatherings.
It is also important to include all land slide risk reduction initiatives for works in progress and at developmental stages for all government agencies, and private works. In order to implement or redesign ongoing works and new initiatives.
Trinidad and Tobago Guardian On-line, Published Saturday, December 30, 2017
Office Of Disaster and Preparedness, Retrieved on 17th November 2018.
Town and Country Planning Act Chapter 35:01 Act 29 of 1960 Retrieved on 17th November 2018.
LOOPTT 27th August 2018, Retrieved on 17th November 2018.
Effective Management of Land Slides, June 15 2017, Retrieved on 17th November 2018.
The University of the West Indies Seismic Research Centre. Accessed November 21, 2018.
“Landslide.” Earth Facts and Information. Accessed November 21, 2018.
Guri, Pardeep Kumar, P. K. Champati Ray, and Ramesh Chandra Patel. “Spatial Prediction of Landslide Susceptibility in Parts of Garhwal Himalaya, India, Using the Weight of Evidence Modelling.” Environmental Monitoring and Assessment 187, no. 6 (2015).