Etude spatio-temporelle du changement de la végétation de la région ouest de Biskra. Approche cartographique par télédétection

Abstract

As a matter of fact, the Ziban region economic development is based essentially on agriculture. Thus this work is realized in the region of Tolga using diachronic analytic descriptive approach in order to determine the changes resulted from the expansion and/or shrinking of the areas occupied by the natural ecosystem vegetations including the oasis ecosystem. The methodology which is applied focuses mainly on the analysis of NDVI of satellite images and field work. The floristic analysis has shown an important biological diversity, one half is vivace species and another half is seasonal species, with biological types dominated by chamaephytes then therophytes. In a duration of twelve years (1999/2010), we have noticed that the change of vegetal carpet could vary from a minimal value of 3 % during the very dry periods (1999) to more than 95 % in rainy periods (2010).In addition to the efforts of developing oasis agriculture via the expansion of about 1110 ha dates’ palm-trees in twelve years, that is 100 Ha per year. By comparing our findings to the agriculture department data, which are obtained by the accumulation of data, we can notice that our results are too close to that of the department. According to these results, which were got by the smart use of the bi-date (1999-2010) satellite data, we have established a collection of interpretative-photo cards and vegetation indexes; which are so helpful in decision-making.