2. What types of drought and desertification exist?

Drought and desertification relating to soil:

  • reduction in soil thickness;
  • reduction in the organic matter of soil;
  • reduction in the fertility of the soil;
  • formation of a crust/compaction of soil;
  • increase in the frequency/intensity of dust winds or in the formation and movements of dunes;
  • reduction in the quantity and quality of surface and/or underground water;
  • effects on rainfed agriculture which constitutes a large proportion of agriculture in some countries, for example in Africa (the Sahel and the Maghreb);
  • irrigated agriculture is also affected: water restrictions can affect the irrigation of crops and domestic uses of water, such as watering gardens;
  • increased drying up of sources and small watercourses;
  • deterioration in ground reflectance (change in albedo).

Drought and desertification relating to biodiversity:

  • reduction in plant cover;
  • decrease in biogases;
  • reduced levels of production;
  • alterations to the distribution and prevalence of key species;
  • deterioration in reproduction levels of key species.
  • loss of forest and animal species (as the forest is increasingly used as a source of firewood).

Drought and desertification relating to animals (livestock):

  • alterations to the distribution and prevalence of key species;
  • change of composition of herds;
  • decline in the reproduction of cattle.

Drought and desertification relating to socio-economic aspects:

  • changes in the uses of soil and water;
  • changes to the occupation patterns of a given territory (i.e. abandonment of villages);
  • changes in the population (demography, migration, public health);
  • loss of harvests and resulting difficulties (especially among rural populations) in satisfying the needs of both humans and livestock since prices of agricultural produce increase under the effects of drought;
  • emergence of diseases;
  • exacerbation of poverty, rural depopulation and mass migration;
  • intensification of conflict between different groups or tribes, potential marginalisation, changes to dependence and wealth structures;
  • appearance of locusts, which pose a threat for rural populations or across entire countries.

Above all, we have to distinguish between drought and aridity. Indeed, the last one, is a constant climatic phenomenon to which the human was adapted. Nevertheless, the drought is a brutal and irregular reduction of water (Dauphiné, 2003).

Indeed, arid regions populations had developed, by the time, indigenous knowledge allowing them boosting spaces in desert environment (oasis).
The drought, starts like a climatic event in its initial phase, extends gradually to all the fields where water forwards. Thus, it is fundamental to distinguish various types of drought:

  • Meteorological (lack of precipitations),
  • Agricultural ( when the conditions are not able to support agriculture and breeding),
  • Hydrological (lack of water in brooks and aquifers),
  • Socio-Economic (when the insufficiency of water starts to affect people and their lives),
  • The forest drought (refers to the situations where the moisture of the soil and the water reserves become insufficient to satisfy the needs for the trees, the herbaceous plants and forest fauna).
Figure 5: Arid Oued in semi- Arid Region (Algeria)