تطبيق نموذج جافريلوفيك لتقدير مخاطر التعرية المائية في حوض وادي نعمان بوسائل تقنيات الاستشعار عن بعد و نظم المعلومات الجغرافية

الملخص EN

The Naman basin is considered to be one of the most important water and agricultural hinterlands of Makkah Al-Mokarramah City.

The basin contains good natural resources which enable substantial agricultural development, as one quarter of the basin consists of thick soil with moderate capability of holding water.

However, previous studies of the basins indicated a decrease of agricultural lands and productivity as a result of soil degradation by torrents.

The researcher chose Gavrilovic’s model, which was designed basically for mountainous areas, to determine the surface water erosion hazards in the basin.

This model was applied using the remote sensing and geographic information system techniques.

It was possible to compute the basin’s erodibility as well as the annual erosion rate for the whole basin and sub-basins based upon pixel unit calculations.

It was evident the foothill and the areas toward the basin outlet are subject to torrents affect as a result of basin’s geologic structure, steep slopes, poor vegetal cover which is important factor in slowing the runoff, and weak human management for retarding flood effect on soil erosion.

This study concluded that all basin is under water erosion with different rates, where erosion is greater in the south and west.

In contrary, erosion is weaker in the basin’s northern source.

It was also concluded that more than half of the basin is under considerable erosion hazards, and about 18 % of the basin is in very erosive states.

The annual rate of water erosion is estimated to be 528 m3 / k2 / year.

The lower basin, Rahajan and Mojairish basins are the most effected by water erosion hazards.

It is recommended to adopt certain measures and procedures, particularly in the upper sub-basins to control erosion hazards in the basin.