Geospatial Technologies in Disaster Risk Reduction

Most people are familiar with the Global Positioning System (GPS) being a technology that has become increasingly prevalent in day-to-day life. Geographic Information System (GIS) however is less well-known, but without GIS, GPS could not possibly be used to its full potential. GPS is a satellite-based navigation system, and GIS is a software program designed to store and manipulate the data that GPS accumulates. Each of these system has its own unique capabilities, but when paired together, they create an invaluable resource for a variety of disciplines including Disaster Risk Management.

A GPS operates in any weather, anywhere and at all times and while it functions to simply give the location of the receiver, the level of precision of GPS makes it an integral part of Disaster Risk Management. In this context, a short training was conducted on Friday 16th June at the Department of Risk and Disaster Management (DRDM). The purpose of the training was to introduce staffs to the basics of using a GPS to capture coordinates and using a GPS to map spatial coordinates in GIS. The participants were firstly briefed on the basic steps of checking that their GPS units were set-up correctly such as type of batteries, ensuring that the GPS units are configured to the right coordinate system, the functions of each button on the GPS unit and also how to navigate their way around the unit so as to understand how the unit worked. The participants were also instructed on the best way to capture and record GPS coordinates on sites, as well as instructions on how to load and display spatial data in QGIS. This training is relevant in line with a project that DRDM is currently implementing to update its existing GIS database which will record information about all incidents and site visits conducted across the country. The information recorded in the database will then later be used to create maps and also for statistical purposes. Following this first training, a practical field exercise will be organized so that participants will now get hands-on experience with using a GPS.

Soil Piping

Soil piping – Should it be a concern for our beautiful islands in its peak of its development era

What is soil piping?

Piping occurs when water erodes  beneath the surface of the ground creating an underground tunnel known as soil pipe. This usually begins as small pores underground and are enlaged with increase erosion, in some instance these hole may be even large enough for a person to crawl through.

In areas where there are craks in the soil or areas of less resistance , water will start to move through creating  a void. Eventually after constant erosion the surface layer of the ground will not have any support beneath and thus collapse creating a depression.  In some other instances  the soil pipe can be formed from openings in the ground that has been left behind when plants died or trees have been uprooted. Animals can also help create soil pipes by burrowing and tunneling in the soil. These voids provide an opening for moving water and create ideal situations for soil pipe formation.

Soil piping is a common feature along side river bank leading to river bank failure. As water seeps beneath the river bank it creates an alternate route, this is eroded and shaped by the water forming a channel (soil pipe). As more water seeps into the bank, the soil becomes heavier and more likely to break apart making it prone to erosion and failure. Soil piping has been related to earth dams failure, dike failures and formation of sink holes.

Soil piping on a property at Bel Ombre

 

How can you identify soil piping?

Since it occurs beneath the soil it makes it difficult to identify the soil pipe up until the ground has collapsed. Small openings known as flute holes connect the soil pipe to the surface. These are often found in the river bank, though they are not easy to spot they help researchers to locate soil pipes before massive soil failures occurs.

Can soil piping be regarded as a Risk?

Soil piping is a natural process, but  often human induce activities may result in change in surface and underground water flow and result in increased subsurface erosion and making soil pipe a potential risk. Soil pipe collapse may become a threat to farming and can threatened the stability of a building.

In Seychelles there already had been a few sightings of depressions that can be identified as a result of soil pipe collapse. Each of these depressions varies in diameter and often runs deep in the ground. In most common cases these depression are found around the house that has been built on underground water sources or next to rivers. These depressions are only noticeable after several years later. In these areas soil subsidence may also be observed. In worst case scenarios several depressions have been located in the same area which makes the area unsafe to walk on. Luckily so far we have not experience any massive failures. However, in areas where the depressions have been found, houses have been rendered unstable as the soil subsidence causes the walls of the houses to crack. Collapsed embankments or retaining walls next to rivers have also been as a result of soil piping.

A sink hole which is a massive failure that may be as a result of soil piping.
Effects of soil piping on dams

 

What is the way forward? Are there any solutions we can adopt?

Understanding more about soil piping is a way forward to avoid massive soil failure in the future. Firstly, new developments need to take into account past history of the area in terms of underground water flow and not only focus on the terrain and surface flow of an area.

There’s also need to emphasize more on integrating our natural environment in development instead diverting, backfilling and drying up our rivers and marshlands. Proper mitigation measures should be put in place when building next to the river including the implementation of buffer zones to maintain the various riverine processes and also protect its natural resources.

When considering flood defence, there are always new engineering solution that can be adopted while constructing embankments next to a river to reduce the effect of soil piping. As illustrated on Figure 4 below, a cut-off is added at the base of the wall, this increase seepage length, therefore reduces exit gradient and also stabilise the base of the wall.

flood defense structurally design to withstand piping

Biological Hazard

This past December marked the 32nd Anniversary of the Bhopal disaster—3,000 people were killed and another 170,000 injured when a pesticide plant in Bhopal, India, leaked chemical substances into the air. Regarded by many as one of history’s worst industrial accidents, Bhopal remains a horrific reminder of risks we continue to face today in an ever-industrializing world.

According to the Centre for Research on the Epidemiology of Disasters, Asian Scientist (Oct. 1, 2012) – Spanish researchers have identified 23 atomic power plants that are more prone to suffering the effects of a tsunami, after one struck the Fukushima Dai-ichi power station in Japan that led to the meltdown of three reactors in March 2011. In the study published in the journal Natural Hazards, the researchers drew a map of the world’s geographic zones that are more at risk of large tsunamis. As such phenomena are still difficult to predict, the authors used historical, archaeological, geological, and instrumental records as a base for determining tsunami risk. In total, they found that 23 plants are located in dangerous areas, including Fukushima I, with 74 reactors located in East and Southeast Asia.

These types of hazards are what we call Technological Hazards. The UNISDR definition of technological hazards refers to hazards that stem from technological or industrial conditions. This includes accidents, dangerous procedures, infrastructure deficiencies, and specific human activities that can cause death, injury, disease, or other health impacts, as well as jeopardize property, livelihood, and services, provoke social or economic disorder, and cause environmental damage.

Examples of technological hazards include industrial pollution, nuclear radiation, toxic wastes, dam failures, transport accidents, factory explosions, fires, and chemical spills.

Technological hazards can also result directly from the consequences of an event related to natural hazards, as in the case of the explosions of two nuclear reactors with the associated hazards of radioactivity in Fukushima, Japan, following a tsunami that accompanied an earthquake.

This category of hazards encompasses a very wide range of events and associated potential impacts on health.

What about Seychelles?

We take a look of Seychelles, an ever growing and developing economy, we neither have been spared of such hazards. We have had various cases involving such hazards especially with anhydrous ammonia in the country.

Burst tank at IOT which caused flooding (August 31st 2015)

 

What is the big deal with Ammonia?

Anhydrous ammonia is used in refrigeration systems (cold storage) for cooling and freezing. Companies started using it in the 1930s, and it still sees a lot of use today. Because its boiling point is low, it is one of the most efficient refrigerants on the market today. Although it’s used mostly in commercial applications, it plays a major role in keeping things cool today.

Even though ammonia fumes are toxic, it does not have a large impact on the environment. Unlike CFCs, which are hazardous to the ozone level, it has a minimal effect on the soil and water systems. Global warming is another concern, as greenhouse gasses form a shield and insulate the earth. However, ammonia does not contribute to global warming. In fact, it has no global warming potential at all.

A number of accidental releases of ammonia have occurred from refrigeration facilities in the past. Releases result from a number of situations that include plant upsets leading to over pressure conditions and lifting of pressure relief valves; seal leaks from rotating shafts and valve stems; refrigerant piping failures due to loss of mechanical integrity from corrosion; and hose failures that occur during ammonia deliveries. Some of these incidents have led to injury and fatalities onsite as well as causing adverse off-site consequences. In addition to risks of personal injury, ammonia releases have the potential of causing significant collateral damage including: product loss due to ammonia contamination, interruption of refrigeration capacity, product loss due to refrigeration interruption, and potential for equipment and property damage resulting from the incident.

What now?

Thus, there is a growing need to redress the Seychelles technical hazard management system in the country. The promotion of sound management of technological hazards in Seychelles, calls for appropriate institutional, policy, legal and administrative arrangements to be in place. An effective legal and policy framework for the management and control of chemicals should be multi-sectoral with the ability to promote a coordinated approach.

To date, no global agreement is in place for preventing and preparing for technological disasters. While there are a number of regional and sectoral frameworks, as well as mechanisms and policies to address various types of technological disasters, we lack an overarching framework that is equipped to address the sheer complexity of issues and diversity of actors involved.

The post-2015 framework for Disaster Risk Reduction (DRR) (The Sendai Framework) offers a unique opportunity to address precisely this, and it gives us a real opportunity to strengthen national coordination and legislative frameworks, and to expand the capacities of all stakeholders for all risks, including technological hazards.

Coastal Erosion Hazard

Erosion is the loss or displacement of land along the coastline due to action of wave, current, tides wind-driven water, or other impact of storm or tropical cyclone, it also means the loss or displacement of land due to the action of wind, runoff or surface water or ground water seepage.

Why does coastal erosion need to be managed?

In Seychelles there are three main reasons why the coast needs to be protected and they are environmental, economical, and social.

Environment: Natural protective features i.e. beaches, and dunes within coastal hazards areas provide buffering and protection to shore lands from erosion by absorbing the wave energy of open water, the sheer force of the water can be

 

damaging to plant life and can destroy habitat, on the dune and can disrupt the whole coastal ecosystem, the eco-status of our coast and shore is highly important for the wellbeing of all Seychellois.

Economic: The tourism industry is one of the main pillars of our economy and most of our hotels are located on our coastal areas. Coastal erosion, with other common phenomena like sea-level rise and climate change has a direct impact on this industry. Our  Beaches are being damaged, business may shut down and jobs are at risk.

Social: About 30% or more of our population lives on the coastal zone. Houses and buildings are threatened by the rapid coastal erosion, house prices will increase and they may refuse or deny house insurance cover due to the increase of the risk of erosion, power stations and other critical facilities near coast are in critical status due to the loss of land , many will face closure or relocation, farmlands lost and salt intrusion may reduce yield which also causes drop in income.

 

Severe beach erosion at Anse La Mouche

 

 

 

(Coastal erosion is silent killer that is effectively taking away the life of coastal region over Seychelles)

Coastal erosion are cause by many factors, including natural processes and human induces activities, the aforesaid mentioned are briefly discuss.

Natural causes of coastal erosion.

Coastal erosion is a natural phenomenon , an endless redistribution process that continually changes beaches, dune and bluffs wave currents tide wind driven water, rain  runoff and ground water seepages all move sand , sediment and water along the coast.

Other contributing factors that can significantly increases coastal erosion of a natural protective feature include length of fetch, wind direction and speed, wave length, height and period, nearshore water depth  tidal influence  and overall strength and duration of abnormal event i.e. cyclones and storm surges.

A combination of these factors and events can amplify these effects by increasing water level, increase storm surges, increasing the distance wave reach inland and producing damaging waves;   along the shore scouring beaches and dunes area reducing sand from beaches and allowing water and wave action further inland intensifying coastal erosion of beaches and dunes.

Human causes of coastal erosion

Human activities. Such as construction, shipping, boating and recreation can increase coastal erosion of sandy beaches, and dunes.

Even though natural events play a major role in coastal erosion process human actions can intensify the effects of these process and speed up the coastal erosion process.

Human’s contribution to the coastal erosion process are:

  • Removing vegetation, exposing bare dune to be easily eroded by wind and wave action and water runoff
  • Directing runoff from roads parking area and others location over the dune edge causing it to erode
  • Constructing hardened structure on the shore that block movement of sand along the coastline, reflect wave action onto adjacent shoreline. Or cause deepening of nearshore area, those structure  also change current pattern
  • Building without considering the potential for damage to property or natural features
  • Activities which destroy natural protectives features such as dune and vegetation

Erosion control measures tried in Seychelles

The commonly employ method are:

1. Hard Erosion control measure, Hard erosion control measures which has been used are Groins more visible at Anse Keralan Praslin, use to deflect tidal current away from shoreline and control movement of beach material, Rocky armouring at Anse La Mouche Mahe, large rocks place at the sea edge used to absorbs wave energy and hold the beach materials, they serve as semi-permanent infrastructure, these structure are not immune from normal wear and tear and will have to refurbish or rebuilt, they have a life span.

Rock Armour at Anse La Mouche Mahe, protecting both the shoreline and infrastructure

Disadvantage of them is that they deprive public access to beaches and drastically alter the natural state of the beaches, they can alter or reduces the interval of natural beaches nourishment process, and sand movement with current and season, expensive to build and maintain.

 

 

 

 

2. Soft erosion control measures

Soft erosion strategies can also refer to temporary option of slowing the effects of erosion, these including sandbags, artificial beach nourishment, and bollard and picketing to make barriers like wall, dune reforestation with native species, and maintaining native vegetation such as mangrove, and veloutyer .

 

Wooden poles erected to build wall like structures to protect shoreline, from wave energy

 

 

 

 

 

3. Relocation

Moving human and cancelling all activities in the affected area of the coast and surrender the coast to the natural process of the ocean and the environment, relocation could also simply mean moving human and its activities further inlands.

Proposed Measures to prevent and reduces coastal erosion

  • Promoting and preserving the natural protective features, such as dunes, and vegetation
  • Restricting and prohibiting activities or development in natural protective feature area
  • Ensuring new construction or structure are a safe distance from areas of active coastal erosion and impacts of storm surges
  • Political accountability
  • Clear role and responsibility in coastal zone management of Ministries and line agencies
  • Provide suitable access point for beach users and appropriate parking bays.
  • Reviewing coastal Management policies or act to suit our local circumstances
  • Take long term views in planning ahead for the future to ensure that current management system will have long term benefits for the coast.
  • Restrict development of the undeveloped coast
  • Develop a comprehensive educational and communication programme aimed at all level, (Government, local, private, schools E.T.C) to increase awareness about Risk due to coastal erosion , and extreme wave condition and their environmental implication
  • Encourage soft engineering solution in affected areas

If you have a beach property you will not be able to leave to your children as an inheritance because it will be at risk of  erosion or underwater, unless you take proactive measures of addressing these risks.

 

Mr. Cliff Alissop

Senior Disaster Management officer

Department of Risk and Disaster Management

Global Village

Mont Flueri

 

 

Tropical Cyclone Bondo and Fantala

The 10 Year Difference on between two Tropical Cyclone on Farquhar : Tropical Cyclone Bondo and Fantala  

The Farquhar Atoll has been hit by two tropical cyclone in last decade. In December 2006 tropical Cyclone ‘Bondo’ made landfall and 10 year later the Atoll was again hit by  the Tropical Cyclone ‘Fantala’ in March 2016. Part of the Seychelles Archipelago, the Farquhar Atoll is a set of ten small islands. It is situated 770km South-South-West of Mahé Island. Farquhar is the largest atoll of the Seychelles, covering an area of about 17,800 ha. The larger islands, North Island and South Island, make up 97 percent of the landmass of 799 ha. Three small islands, known as the Manaha Islands, separate these areas. Three other islands, Déposés, Ile du Milieu, and Lapins, lie in close proximity to one another on the northern rim of the atoll. Banc du Sable and Goëlettes are the most easterly, and the most southerly islands, respectively. Farquhar Atoll has become renowned for its marine based ecotourism and particularly for fly-fishing activities.

The Tropical Cyclone ‘Bondo’ made landfall on the 19th December 2006. In preparation the Island Development Company (IDC) evacuated 35 of its 43 residents that was on the island. The remaining eight stayed on the island in an emptied concrete water storage tank that they use as bunker during the storm. The workers that remain behind cleared the runway, and also to carry out the first assessment the impact of the cyclone.

Ten years later on the 17 and 19 April 2016, the Atoll was again hit by the strongest tropical cyclone ever recorded to have developed over the Indian Ocean basin; Tropical Cyclone Fantala which was the sixth cyclone occurring during the 2015/16 tropical cyclone season. It made landfall twice on Farquhar Atoll, damaging almost all the infrastructure and coconut palm tree groves on the atoll.

There is no record of the economic impact figures in regards to TC Bando but the effect of TC Fantala are estimated at SCR 101 million, equivalent to US$7.5 million of which SCR36.5 million (US$2.7 million) are due to physical damages and SCR 64 million (US$4.8 million) are due to changes in economic flows, or losses. The sectors that was affected was mostly environment, tourism and military as their monitoring equipment was badly affected.

Tropical cyclone within the Indian Ocean is a natural occurrence that is on the increase with the outer island of Seychelles being more susceptible as they further from the equator. Their remoteness and accessibility add to their vulnerability. Effective preparedness, response and monitoring was the key during both cyclone. Early warning from the Seychelles Metrological Services and Division of Risk and Disaster Management at that time to all partners concerned has ensured that there was no loss of life. Farquhar being ravage by the two cyclone at a ten year interval is clear example of the effect of climate change and that the lapse of time between an occurrences is getting smaller whist the impact of the aftermath is increasing.

Intense Tropical Cyclone Bondo
Intense tropical cyclone (SWIO scale)
Category 4 (Saffir–Simpson scale)
Intense Tropical Cyclone Bondo on December 20
Formed December 15, 2006
Dissipated December 28, 2006
Highest winds 10-minute sustained:205 km/h (125 mph)
1-minute sustained:250 km/h (155 mph)
Gusts: 285 km/h (180 mph)
Lowest pressure 930 hPa (mbar); 27.46 inHg
Part of the 2006–07 South-West Indian Ocean cyclone season
Very Intense Tropical Cyclone Fantala
Very intense tropical cyclone (SWIO scale)
Category 5 (Saffir–Simpson scale)

Fantala north of Madagascar on 18 April
Formed 11 April 2016
Dissipated 27 April 2016
(Remnant low after 23 April)
Highest winds 10-minute sustained:250 km/h (155 mph)
1-minute sustained:285 km/h (180 mph)
Gusts: 350 km/h (220 mph)
Lowest pressure 910 hPa (mbar); 26.87 inHg
Part of the 2015–16 South-West Indian Ocean cyclone season

Disaster Risk Reduction for Sustainable Development

If you remember my last blog was about Disaster Risk Reduction (DRR) being everyone’s responsibility, this is also true for the Sustainable Development Goals (SDGs) Agenda 2030. Recently two of DRDM staff along with various Government and Private Stakeholders attended a two-day national dialogue aimed at integrating the SDGs into national plans and budget in Seychelles.

Figure 1: The 17 Sustainable Development Goals Agenda 2030

Sustainable Development and DRR are closely interlinked. Disasters have a devastating impact on development. Families lose homes, livelihoods and loved ones, communities lose businesses, jobs and services, children and particularly girls miss school and are at risk of early marriage the list of impacts goes on. It therefore undermines the Goal 1 which explains ending poverty in all its forms everywhere. Furthermore disasters jeopardize agricultural production and development and often have cascading negative effects across national economies. Natural hazards regularly impact heavily on agriculture and hamper the eradication of hunger and achievement of food security. Similarly this underpins the goal No 2 which focuses on zero hunger. Also disasters may result in the damage or destruction of learning facilities and materials, the closure of schools and the prolonged disruption of education, increased barriers to education, limited access to schooling, and decreased education quality and thus undermines the goal No 4 which talks about ensuring inclusive and equitable quality education and promote lifelong learning opportunities for all. And the list goes on and on.

The role of DRDM is primordial in Disaster Risk Reduction and Management and thus building resilience of Seychelles to Disasters. Unless disaster risks are effectively reduced and managed, loss and damage by disasters will continue to undermine efforts to achieve Sustainable Development.

The Government of Seychelles is committed to the implementation of the SDGs Agenda 2030.Recently the Cabinet approved the creation of a national oversight and strategic committee for the implementation of actions related to Seychelles’ regional and global commitments, including the 2030 Sustainable Development Goals Agenda.

 

Disaster Risk Reduction: Everyone’s responsibility

Disasters are serious disruption of the functioning of a society. From the start of this year, the world has experienced many disasters. Few examples are the chemical attacks on civilians in Syria, the infestation of fall armyworm in many Southern African countries and most recently the huge forest fires in Portugal. Similarly, Seychelles have experienced incidents, though not on the same magnitude as other countries. For instance we have seen incidents such as frequent house fires, ammonia leakage and dengue outbreak.
Disaster Risk Reduction (DRR) aims at reducing disaster risk, promoting sustainable development, protecting persons and their property, livelihoods, health, as well as cultural and environmental assets. Through DRR countries can build resilience to disasters. It involves all of us, from the least to the most vulnerable in our community and society. It begins with efficient and effective disaster risk governance in the country. This involves investing in DRR, establishing programs to inculcate a sense of prevention in communities, introducing DRR into education curricula and disseminating DRR knowledge to youth club etc. DRR involves all sectors. Thus there needs to be effective coordination mechanism within and across sectors. This will ensure proper allocation of roles and responsibilities across public and private stakeholders so that accountability, transparence and follow-up can be made. Additionally each individual should take its own responsibility to change mindset, behavior and perception on DRR. In many instances people have shared indigenous knowledge on DRR which have been of great help to prepare and respond to disasters. On another note people have refused to follow best practices out of their own personal choices which have led to disasters or they themselves have become victims in times of disasters.

Seychelles as a Small Island State is working towards DRR. The Department of Risk and Disaster Management has started to conduct Risk Assessment of the industrial sector and other government ministries. These are aimed to identify hazards and risk in the workplaces and community and find ways and solutions to minimize them. Furthermore educating the public on the importance of DRR remains a priority and strategy for the department. However we still have a long way to go. We shall achieve more through the engagement and partnership of all of us in the society.

Slope Failures – Causes and Mitigation

What are Slope Failures?

Slope failures are major natural hazards occurring both globally and locally. They are referred to as the downslope movement of rock debris and soil in response to gravitational stresses. Slope failures are generally classified according to the type of downslope movement namely falls, slides, and slows. Unfortunately, slope failure is a geohazard that impacts a wide range of landscapes and also many types of infrastructures.

Landslide at Pascal Village, Mahe.

 

So, what causes Slope Failures?

Rockfall at La Batie, Mahe.

 

Like all geohazards, the causes are myriad and complex. Generally speaking, slope stability is based on the interaction of two forces namely driving and resisting forces. Driving forces promote the downslope movement of slope material whilst resisting forces resist movement. Common causes of slope failure include:

  • Slope Steepness: Steeper slopes have greater risks for instability. The natural tendency of steep slopes is to move some of its materials downwards until the natural angle of repose is found. Any form of slope modification will eventually impact the stability of a slope.
  • Drainage and Stream Action: Excessive water in slopes is never good as it destabilizes the slope by adding weight, destroying cohesion between grains, and reducing friction. When water takes the place of air between the grains of soil, it will most likely increase the probability of downslope mass movement and lead to slope failures as the earth in slopes become a lot heavier. Streams can also erode away the bottom of the slope overtime resulting in decrease in slope stability.
  • Vegetation: The amount and type of vegetation on a slope is proportional to the strength of that slope. Generally, the roots of vegetation hold the soil in place and makes it more resistant to erosion. Therefore, the more vegetation present, the more stable the slope is likely to be.
  • Human Modifications: Humans modify stability of slopes in many ways which may trigger the sudden mass movement of the soil in slopes. Such includes the excavation and removal of the slope’s base to build roads, the passage of heavy trucks, blasting, loading of the slope or crest, surface or groundwater manipulation, irrigation and mining.

Slope Failures Mitigation Measures?

Landslide at Montagne Posee, Mahe.

 

Slope Failure Mitigation or Repair, is not a one-size-fits-all task.  The materials to be used as well as the reinforcement design are influenced by a myriad of factors. Some of the common methods used for slope failure mitigation and repair includes:

  • Proper Drainage: Plans to repair a slope must be accompanied by drainage rehabilitation plans. The planned drainage system must be able to efficiently channel water away from the slope without affecting slope stability or causing erosion. Weep holes in retaining walls and French drains are just two of the more popular drainage options.
  • Terracing & Benching: The nearer a slope is to its natural angle of repose, the more stable it is. It is for this reason that terracing or benching is a popular way of dealing with steep slopes.  This involves making the slope more manageable by dividing it into several smaller and less steep slopes reinforced by retaining walls and friction piles, to name a few.
  • Retaining Walls: Retaining walls are used to stabilize the slopes surrounding a property. Concrete retaining walls are walls that are designed to “retain” or hold in place a substantial amount of soil. They are built on the lower part of a slope to directly suppress a collapse of that part and also to check coming-down collapsed soil and stop it before houses.
  • Soldier piles and Lagging works: This slope stabilization technique often used in projects involving soft soils. Sheet piles can be made of wood planks, vinyl or steel. Piles driven 2/3 of their length into the slope towards load bearing strata (layer that can bear stress) to restrain the collapse of the surface soil layer and installed in such a way that the sheets overlap. Sometimes, lagging or panels are installed between piles to form a retaining wall that will prevent the downward movement of soils.
  • Rock Bolts: Much like piles, rock bolts are used to stabilize slopes that are composed mainly of fractured rocks. The bolts connect the fractured and weak surface to the stronger rock layers underneath, giving the slope stability.
  • Grating Crib: Concrete frames are laid on a slope, within which plants grow to protect the slope from weathering and erosion. It is also possible to directly suppress slope collapse by using the frames in combination with ground anchors, or to allow trees remaining on the slope to be retained by adjusting the arrangement of the frames.
  • Biotechnical Slope Stabilization: In layman’s terms, biotechnical slope stabilization is simply letting plants and vegetation stabilize a slope. Vegetation is good for slope stability and planting different layers of vegetation on the slope is an effective way of stabilizing this slope.

Based on the above discussion, you should realize that repairing a slope and preventing a landslide is not a simple task. If you’re going to do it, then you should do it right. Band-Aid solutions will only be a waste of money as they could also give you a false sense of security, which could ultimately cost you your house and out your family at risk. If your house is on a slope or located near one, get the slope inspected to understand if you are at risk and, if you are, learn about the best slope failure solutions that you can apply to mitigate such risk.

Hairy Caterpillar

Lentrodiksyon

Resaman, Sesel in ganny afekte par en gro lenfestasyon senir plim Euproctis spp. dan diferan landrwa lo Mahe, Praslin, La Digue e Ile Aux Cerf ki okazyonn reaksyon alerzik, prensipalman grate e lagretel lo lekor nenport ki ki antre an kontak avek sa kalite senir.

Sa pes i osi poz en gro problem sosio-ekonomik dan lanvironnman e dan kominote.

Pou arive ganny en program kontrol efikas kont senir plim, nou oule donn konsey e ankouraz Piblik An Zeneral/Biznes/Lenstitisyon dan bann kategori swivan pou donn tou zot korperasyon, kontribye e pran zot responsabilite pou ………………

Konn Sa Pes

Senir plim i detri fey lo pye dibwa akoz en kantite zot pe manz sa bann fey a la fwa. Sa pes i anan kat (4) staz devlopman ki ganny vwar lo plan oubyen pye dibwa ki’n ganny enfeste. Sa i staz dizef, larv (senir) e staz adilt.

Staz Devlopman

Adilt – Lay adilt i tou blan.

Staz Dizef

Dizef i ganny ponn anba fey e i paret en kouler krenm pou al lo gri.

Larv (Senir)

Bann nouvo pti senir i ganny vwar an group, kouler gri pou al lo zonn. Senir ki’n fini devlope i anan plim kouler zonn avek tas nwar.

Staz Pupa (kot sa senir i komans vinn adilt)

I dan laform oval e paret kouler gri.

Ki Manyer Pou Kontrol Sa Pes

Pou determinn prezans sa pes, fer lenspeksyon lo plant e pye dibwa avek prekosyon.

Si ou vwar plizyer senir lo plis ki 3 fey, sa pes i kapab ganny kontrole an servan Javel e Solisyon Savon  melanze avek pestisid delwil oubyen aerosol pou anpes zot plim anvole.

Si lenfestasyon lo fey oubyen serten parti en plant i plis ki saki’n mansyonen, alor Prodwi Pestisid ansanm avek bann Pratik Kiltirel i kapab ganny aplike pou kontrol sa pes.

 

Ki pou fer pou kontrol sa Pes?

Kontrol Kiltirel oubyen stratezi i enkli bann taktik ki fer landrwa kot sa senir i reste mwen konvenyan e i ganny konsidere koman mezir prevansyon, tel parey:

  • Lafimen i kapab servi ler napa restriksyon alim dife.
  • Koupe, taye oubyen detri bann fey/plant ki’n ganny enfekte e larg zot dan en resipyan ki anan petrol oubyen dyezel. Answit anter dan en trou.
  • Koupe, taye e bril bann fey/plant ki anan dizef, senir e lay ler napa restriksyon ki anpes alim dife.
  • Kre landrwa ki pa favorab pou senir plim (Euproctis spp.) ponn i osi kapab ede.
  • Retir landrwa reste kot senir plim (Euproctis spp.) i kasyet, reprodwir, ponn oubyen reste.

Kontrol Mekanik i kapab en zouti itil pou kontrol (Euproctis spp.) me i pa pou eliminn son popilasyon oubyen anpes en lot gro lenfestasyon.

  • Destriksyon bann dizef an gran kantite i kapab itil dan kad program IPM.
  • Dimoun kot lakaz e bann ki plante ki oule detri dizef anba fey an gran kantite pou nenport ki rezon i devret fer li avek bokou prekosyon an servan bann opsyon pou protez zot.
  • Kolekte dizef ek bann zenn larv e detri zot.

Kontrol Fizik I kapab ede redwir popilasyon sa pes an servan lekipman ki afekte zot fizikman e sanz zot lanvironnman.

    • Lalimyer an servan glob ki redwir konsomasyon elektrisite (energy saver) enstale lo en resipyan ranpli lanmwatye ek delo savon i osi kapab ganny servi pou atrakte e kontrol sa pes ki dan staz adilt.

Kontrol Biolozik i zwe en rol enportan pou redwir popilasyon senir plim (Euproctis spp.) lo en gran sirfas.

  • Zwazo tel parey marten i zwe en pli pti rol kot zot manz bann senir.

Kontrol Kemikal an servan serten prodwi pestisid pou redwir destriksyon bann fey lo plant e pye dibwa dan sirkonstans kot popilasyon sa senir i vreman repandi, i reste koman deryen opsyon dan lapros IPM.

Nou toultan met lanfaz lo moman apropriye e bon laplikasyon ki probableman eleman pli esansyel ler pou aplik pestisid.

Kontrol Direk (Lekipman Proteksyon Personel i byen ganny servi)

  • I konseyab pou spray plant/pye dibwa ki’n ganny enfekte avek swa en solisyon savon oubyen bleach byen for par melanz ¼ sa solisyon avek ¾ delo pou tretman.
  • Pestisid i ganny rekonmande pou kontrol oubyen redwir lenfestasyon sever. Nou rekonmande pou servi prodwi ensektisid dan Group Pyrethroid parey Decis, Ambush etc..
  • I konseyab pou servi Prodwi Pestisid Bio tel parey Bacillus thurigiensis, Nilinsect, Neemik e Neembaan ki anvant kot ban stor rekizisyon Lazans Lagrikiltir Sesel (SAA).
  • Dimoun kot lakour e bann planter i devret toultan lir byen e swiv lenstriksyon egzakteman parey i endike lo sa bann prodwi.
  • Bann lakonpanyen ki kontrol pes i kapab ganny aprose pou vinn spray depandan lo nivo lenfestasyon e zot devret toultan obzerv bann prosedir proteksyon a tou moman.

Pou plis evaliasyon e rekomandasyon kontakte Lazans Biodiversite lo 4324000.