التغيرات البيئية لحوض وادي نمار للفترة من (2004-2017 م)‎ : دراسة باستخدام نظم المعلومات الجغرافية و الاستشعار عن بعد

الملخص EN

Namar’s valley is one of the important tributaries of the Hanifa’s valley.

It is the large and important watershed in Najd in Saudi Arabia.

Many villages and communities have been settled along its shores, like Diriyah, Jubaila, Al-'Uyayna, El Omaria, and Riyadh.

Namar valley is an environmental system that affects, and is affected by, the surrounding life.

This basin has been exposed to many environmental changes, including human factors and nature’s factors.

In this study, we tried to monitor some of the environmental changes that had taken place in the basin of the Namar valley between 2004 and 2017.

We did so through analysis of the satellite images (Spot5) taken during that period and through use of the ArcGIS program and the ERDAS Imaging method of supervised classification.

The study was focused on the changes in vegetation cover and urban growth in terms of an increase or decrease in the area between 2004 and 2017.

The descriptive approach, which was appropriate to the nature of the study and the achievement of its objectives, was used in this study, and was based on analysis of the satellite images and measurements taken of the geographic phenomena within the water basin.

In addition, cartographic methodology was used to represent and distribute geographical phenomena such as buildings, plants, water, and roads.

The quantity and quality of the image display were clearly shown in the satellite images from the multi-spectral satellite (Spot-5), which has a 10 meter degree of spatial clarity.

The most important findings in the study were the classification of the land cover patterns of the Namar valley’s basin, including the area and distribution of each phenomenon and the extent of the change between 2004 and 2017.

The results showed that there was an increase in the use of residential land estimated at 13 km , which represents 6% of the total area of the basin, and amounted to 218 km .

In addition there are lands prepared for a future urban area, which covers an area of about 7km , which represents around 2.5% of the total study area.

There was a slight increase in the vegetation cover, estimated at 1.6 km , which represents about 0.7% of the total area of the basin over the past 13years.

Recommendations included: the need to review the construction laws in the dry basin, and to intensify and tighten control of the violations in Namar’s valley, including building infringements, violations of construction waste and contaminants, and establishment of industrial and drilling projects.

The study also showed the importance of using the GIS and remote sensing when studying environmental changes because of the GIS’s accuracy, which, thus, saves both effort and time.