Editing IPCC:AR6/SRCCL/Chapter-3 (section)

==== 3.7.2.2 The Green Dam in Algeria ====

<div id="section-3-7-2-2-the-green-dam-in-algeria-block-1"></div>

After independence in 1962, the Algerian government initiated measures to replant forests destroyed by the war, and the steppes affected by desertification, among its top priorities (Belaaz 2003 <sup>[[#fn:r1591|1591]]</sup> ).

In 1972, the government invested in the Green Dam ( ''Barrage vert'' ) project. This was the first significant experiment to combat desertification, influence the local climate and decrease the aridity by restoring a barrier of trees. The Green Dam extends across arid and semi-arid zones between the isohyets 300 mm and 200 mm. It is a 3 Mha band of plantation running from east to west (Figure 3.12). It is over 1200 km long (from the Algerian–Moroccan border to the Algerian–Tunisian border) and has an average width of about 20 km. The soils in the area are shallow, low in organic matter and susceptible to erosion. The main objectives of the project were to conserve natural resources, improve the living conditions of local residents and avoid their exodus to urban areas. During the first four decades (1970–2000) the success rate was low (42%) due to lack of participation by the local population and the choice of species (Bensaid 1995 <sup>[[#fn:r1592|1592]]</sup> ).

The Green Dam did not have the desired effects. Despite tree-planting efforts, desertification intensified on the steppes, especially in south-western Algeria, due to the prolonged drought during the 1980s. Rainfall declined in the range from 18% to 27%, and the dry season has increased by two months in the last century (Belala et al. 2018 <sup>[[#fn:r1593|1593]]</sup> ). Livestock numbers in the Green Dam regions, mainly sheep, grew exponentially, leading to severe overgrazing, causing trampling and soil compaction, which greatly increased the risk of erosion. Wind erosion, very prevalent in the region, is due to climatic conditions and the strong anthropogenic action that reduced the vegetation cover. The action of the wind carries fine particles such as sands and clays and leaves on the soil surface a lag-gravel pavement, which is unproductive. Water erosion is largely due to torrential rains in the form of severe thunderstorms that disintegrate the bare soil surface from raindrop impact (Achite et al. 2016 <sup>[[#fn:r1594|1594]]</sup> ). The detached soil and nutrients are transported offsite via runoff, resulting in loss of fertility and water holding capacity. The risk of and severity of water erosion is a function of human land-use activities that increase soil loss through removal of vegetative cover. The National Soil Sensitivity to Erosion Map (Salamani et al. 2012 <sup>[[#fn:r1595|1595]]</sup> ) shows that more than 3 Mha of land in the steppe provinces are currently experiencing intense wind activity (Houyou et al. 2016 <sup>[[#fn:r1596|1596]]</sup> ) and that these areas are at particular risk of soil erosion. Mostephaoui et al. (2013), estimates that each year there is a loss of 7 t ha <sup>–1</sup> of soils due to erosion. Nearly 0.6 Mha of land in the steppe zone are fully degraded without the possibility of biological recovery.

To combat the effects of erosion and desertification, the government has planned to relaunch the rehabilitation of the Green Dam by incorporating new concepts related to sustainable development, and adaptation to climate change. The experience of previous years has led to integrated rangeland management, improved tree and fodder shrub plantations and the development of water conservation techniques. Reforestation is carried out using several species, including fruit trees, to increase and diversify the sources of income for the population.

The evaluation of the Green Dam from 1972 to 2015 (Merdas et al. 2015 <sup>[[#fn:r1597|1597]]</sup> ) shows that 0.3 Mha of forest plantation have been planted, which represents 10% of the project area. Estimates of the success rate of reforestation vary considerably between 30% and 75%, depending on the region. Through demonstration, the Green Dam has inspired several African nations to work together to build a Great Green Wall to combat land degradation, mitigate climate change effects, loss of biodiversity and poverty in a region that stretches from Senegal to Djibouti (Sahara and Sahel Observatory (OSS) 2016) (Section 3.7.2.3).

<div id="section-3-7-2-2-the-green-dam-in-algeria-block-2"></div>

<span id="figure-3.12b"></span>
<!-- START IMG -->
<!-- IMG TITLE -->
'''Figure 3.12b'''

<span id="location-of-the-green-dam-in-algeria-saifi-et-al.-2015.-note-the-green-coloured-band-represents-the-location-of-the-green-dam."></span>
<!-- IMG CAPTION -->
'''Location of the Green Dam in Algeria (Saifi et al. 2015). Note: The green coloured band represents the location of the Green Dam.'''
<!-- IMG FILE -->
[[File:852f131c5ef11fb337e11742bc73ccae Figure-3.12b-1024x577.jpg]]

Location of the Green Dam in Algeria (Saifi et al. 2015 <sup>[[#fn:r1806|1806]]</sup> ). Note: The green coloured band represents the location of the Green Dam.

<!-- END IMG -->
<div id="section-3-7-2-3-the-great-green-wall-of-the-sahara-and-the-sahel-initiative"></div>

<span id="the-great-green-wall-of-the-sahara-and-the-sahel-initiative"></span>