USING REMOTE SENSING TECHNIQUES AND GIS SYSTEMS FOR THE STUDY OF STRUCTURE ANALYSIS OF THE DRAINAGE BASIN OF WADI ZAZA AND NATURAL VEGETATION COVER IN AL JABEL AL AKHDER AREA, EASTERN PART OF LIBYA

The structural analysis is one of the prime concerns for the dam engineer during the reconnaissance and feasibility stages in dam site selection. Obtaining reliable data in the normal fashion would require tedious collection in the field and measurement in laboratory of a large number of rock samples. The present work has shown that this process can be greatly reduced. Limited field sampling and field checking were based on the image satellite using Landsat 8 of our study area.

The dam reservoir 150 meter above sea level (m.a.s.l) occupy part of Dernah Formation. Field observation and laboratory test show that Dernah Formation is composed of Nummulitic limestone, compact and very hard, brittle and highly fractured. Therefore the Karst evolution is high.

Al Jabel Al Akhder region is characterized by the diversity of forest vegetation and the presence of agricultural land, grassland, palm trees and forests, such as pine forests and forest Juniper, bushes and the trees, oak and others. The study demonstrated that there are several factors led to the ebb and clear vegetation and the lack of forest area among these factors are:

1-The pattern of distribution of plant follows the stages of succession between groups of vegetation present and show stages of the deterioration of the structure of vegetation from the forest to the bush to stage shrubs, and then to a small shrubs and then to phase herbs Yearbook and finally to a barren land.

2- Exposure to forest and grassland fires and the danger of the outbreak of fire as a result of indifference in the use of stoves and waste cigarettes.

3-Overgrazing cause what is known as the early signs of desertification due to the misuse of the Territories vital and thus lead to the destruction of vegetation, the result of attrition and reap the grass green branches.

4-Removing natural vegetation resulting from the timber for the purpose of heating contributed to the reduced vegetation.