Tag Archives: landslide protection

A Case for Improved Soil and Land Use Management in Dominica

Dominica’s national motto “Après Bondie C’est La Ter” meaning “after God is the land” highlights the importance of the land (the soil) to Island. The amount of precious top soil eroded by the torrential rains during the Erika disaster may never be quantified or featured among all we have lost. Nonetheless, losses incurred due to landslides and soil erosion and the subsequent impact on communities and livelihoods highlight the need to elevate the importance of soil and land use management in Dominica.

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The 68th United Nations General Assembly declared 2015 as the International Year of Soil. A primary objective was to raise awareness among civil society and decision makers of the profound importance of soils for human life. As a non-renewable resource, its preservation is paramount for food security and our sustainable future.
Soils are not merely parcels of uniform materials. Instead, they are units with characteristics that change vertically downwards through different layers and horizontally in every direction. Therefore, to describe a soil it is not sufficient to only look at the surface, a vertical cut or boring must be made and the different layers from the surface to the parent material (underlying rock) carefully examined.

The soils of Dominica were classified by Mr. David Lang over 40 years ago. His work provides general descriptions of the major soil types, soil forming processes and includes several important recommendations for land use planning and agricultural development. Mostly, the soils are formed by the weathering of volcanic rock. The weathering process results in the formation of clays and secondary minerals. However, the unique properties of the respective soil types are based on the underlying rock and as influenced by environmental factors, rainfall patterns, topography, vegetation and the extent of weathering.

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The physical and chemical characteristics of our soils, suitability for agriculture and other land uses are largely dependent on the type and quantity of clay they contain. For example, soils along the west coast between Jimmit and Tarreau dominated by Smectite clay minerals are noted for their shrinking and swelling properties. They shrink and crack considerably when dry and expand when wet. This activity is responsible for the cracks and movement frequently observed in the paved roads in that area. The Smectoid clays differ from soils on the north east, around Marigot, which are dominated by Kandite clay minerals. Kandoid clays are generally highly weathered (older), appear reddish to red-brown, are well-drained and better suited for agricultural development.

Several studies have investigated the mechanics of landslides in Dominica. The steep slopes, high rainfall and high water holding capacity of our soils are some of the factors that predispose many parts of the island to landslides. While heavy rainfalls are common in Dominica, it is the prolonged precipitation at high intensities, as occurred with Erika, which is capable of causing serious destruction from landslides.

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Efforts to rebuild Dominica must be focused on building resilience and adapting to climate change impacts. Soil conservation and land use planning based on available technologies and the findings and recommendations generated from scientific studies (most of which already exist) should guide policy decisions and inform activities at the farm and community levels. We must also rely on the practical experience of individuals who have continued in the traditions of our forefathers, by stabilizing slopes with deep rooting crop and forest trees, bamboo and vetiver strips and who willingly adopt the approach that some extra work now can set the foundation for a sustainable future.

Davidson Lloyd (PhD)

Seeds of Hope: Reforestation, Bamboo Cultivation & Land Slide Control

Dominica is mountainous, seismically active and subject to frequent torrential rains. As a result, we have suffered from many landslides over the years. In Hurricane Dean of 2007, we lost a mother and son at Campbell. In 1976, the huge Bagatelle Land Slide left 8 dead and many more wounded. In 1997, a huge land slide in the heights of the Layou Valley blocked the Layou River for some time, and later led to flooding at Layou Village and Hillsborough when the naturally formed earthen dam was breached. Today, in heights of Carholm there is now a new lake, popularly christened Miracle Lake. Miracle Lake is almost 2.2 miles in area and a wonder to behold. It is the only naturally formed lake of its size to evolve in the Caribbean in the past 100 years. It has the potential to become a prominent and permanent tourist attraction if the proper civil and bio-engineering is done. Which brings us to bamboo and its role in bio-engineering: the use of natural products – such as vegetation – to create engineering solution.

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Bamboo is one of the fastest growing grasses and a great source of oxygen. It can be used as furniture, in housing and for clothing material. Some of its young shoots are ideal for salad making. The bamboo we see around Dominica today did not fall out of the sky. In the 1940s Soil Conservation Officer Wendell Christian relates that it was sown on slopes in places like Layou, Giraudel, Eggleston and along the Grandbay road to prevent soil erosion and land slides. My father was one of the recently demobilized soldiers from the British Army recruited in a special program by English Chief Forestry Officer Borer to tend to soil conservation. The plants they used, some imported from Asia, have a dense root network which is ideal for holding the soil. When last was such bamboo cultivation pursued? When have we ever seen a reforestation campaign when ordinary people take to the hills and valleys, seedlings in hand, to sow tree crops or bamboo to shore up the frequently sliding hills of our island home?

In countries like Nepal, which is as mountainous as Dominica, they have been experimenting with the use of grass and shrubs for the last two decades in roadside bioengineering. Various grasses, shrubs and trees have been used as bioengineering techniques by different organizations on a number of highway slopes in Nepal. When vegetative measures are combined with engineering measures, the end result can be effective for landslide protection and dramatic reduction of surface erosion, at relatively low cost and ensuring high sustainability. Bioengineering control measures have been observed to be economically desirable and most effective for erosion control in degraded areas. Hence, planting local grasses, shrubs and trees represents sustainable use of vegetation along with engineering structures to increase slope stability against shallow landslides and to protect almost all slopes against erosion. On small sites, bioengineering techniques alone may be adequate. However, bioengineering is closely integrated with civil engineering structures. In many countries with landslide problems, brush layers, palisades, live check dams, fascines and vegetated stone pitching walls, large bamboo planting, turfing, site seeding and planting grass, shrubs, small trees, large trees, their spacing and plant growing techniques, etc., have been used to preserve their soil cover.

Accordingly, the Dominica Academy of Arts & Sciences can focus on a partnership with our local Department of Agriculture, Public Works, and Forestry Division to revive these sound principles of soil conservation. Though we appear to be a very green island, human activity in the heights of Dominica have led widespread to deforestation. Many rivers are now shadows of their former selves. Many of us still have faint memories of the Roseau River in the 1960s where Silver Lake and Under Power were deep watering holes where bathers would jump from overhanging trees into 15 feet – or more – of water. Today, erosion continues unabated and many rivers are drying up while others resemble stone gullies. Soon, where left unchecked, such erosion will destroy our island where we do not act. As a result of erosion, tons of precious top soil built up over centuries of leaves falling to the ground and decaying, are regularly washed out to sea. Every time we see a local river brown with mud, we are witnessing the slow, but inexorable, washing away of our island.

Seeds of Hope

Without our rich top soil being preserved, we cannot long survive. It is for that reason, we make this call to the members and affiliates of the Dominica Academy of Arts & Sciences to focus on what is a matter of survival. In celebration of the 30th Anniversary of Independence, each member of the DAAS at home – or visiting – can commit to planting some bamboo shoots at a roadside in coordination with the Forestry Department. A fruit tree can also be planted in a village or next to a local school, in coordination with the students who can tend to that tree long term. We will stake a suitable plastic plaque next to each planting to memorialize our contribution and inspire others to engage in similar collaborative effort. This is the time to put love of country before self or partisanship and tend to our very survival.

By this effort we can enhance the experimental analysis of mechanical properties of various root types, such as bamboo. We cannot be spectators to our fate and simply await the next big slide or hurricane while we lose our precious time lamenting leadership that we fail to exhibit ourselves.

Mahatma Gandhi said we must first become the change we desire.

With a modest individual donation of $20.00 towards a seedling for a National Reforestation Campaign – called Seeds of Hope – we can preserve the tierra firma of Dominica.

Where we succeed, we can pass on our worthy experience to other island states and so inspire them.

The contribution sought from each of us is modest; the value, great.

Each tree represents the birth of renewed hope in the victory of our development cause, and shows gratitude to God for the gifts bestowed. Shall we allow the ruin of Eden?

As an academy dedicated to the dissemination of development oriented information, it is high time for the study of mechanical properties of roots, their role in landslide protection in the context of rapid development of roadside bioengineering technology nationwide. Considering the above facts a study is needed on an experimental analysis of strength of local grass and shrubs roots widely used for landslide protection in different countries. By such an effort, alongside, our own Seeds of Hope Project, we can reverse the washing away of our beloved island. And the bamboo and trees so planted can be an added boon to our economy where we can utilize them in industry.

Any persons desirous of being part of Seeds of Hope, can contribute to such a fund set up by the DAAS. We will work with local and international nurseries to get the bamboo and/or tree seedlings. In that manner, every one of us can say we have made, or are making, a contribution to the sustainable growth of Dominica.