Dr. Amina Atallah Abed Rabbo Al-Rehaili

Vol. 17 | No. 1 - 1447 - 2025

Abstract

The study aims to spatial analysis actual value of precipitation, its changes and its effects on changing distribution of vegetation in Taif Governorate, predicting actual value of precipitation and its effect on vegetation in future, through find relationship rainfall and vegetation in the study area. The objectives of study were achieved using (IDW) algorithm to deriving informational layers for variables air temperature, precipitation amounts, and vegetation from image obtained from the NASA website for every eleven years between 2000-2021. and application of Demarton model in GIS environment to derive actual value of precipitation based on two layers precipitation and temperature. Thus, reveal extent effect of the actual value of precipitation on vegetation by calculating relationships coefficient and testing significance of spatial relationships between change actual value of precipitation and change of vegetation. then simulate each other's direction to 2032 using Multi Logistic Reg model in IDRESI Selve- Version 17.

The results of study found an increase in precipitation amount between the two study periods 2000-2011 and 2011-2021, evidenced by an increase spatial average of precipitation by about 16.3 mm, as well as an increase area of the rainiest zones and a decrease area of the less rainy zones. which indicates a positive effect of actual value of precipitation in vegetation, and its negative effects related to agricultural drought in Taif Governorate. which is confirmed by the decline area of the dry climate according to Demarton classification from 10967.33 km2 to 9280.3 km2. and increase area of good vegetation above threshold 0.15 for Normalized difference vegetation index about 818.44 km2, and decrease area of zone is very poor in vegetation below threshold 0.1 about 922.48 km2 between the two periods.

Keywords: Simulation Model, Rainfall, Vegetation, Geospatial Techniques, Taif Governorate