Soil Moisture Routing Using Moderate Spatial Resolution of MODIS Satellite Data A case Study: Esfahan Province

Soil moisture in the root zone is defined as soil moisture in depths of 1 to 2 meter from surface. This moisture is generally available for crop development and can be transported to the atmosphere through evaporation process. Due to the importance of soil moisture for plants growth and in the biology interactions, it is considered as a key factor for agriculture sector. In this research, to evaluate soil moisture routing, Soil Wetness Index (SWI) was derived from reflective and thermal satellite data. For this purposes, 8 day-products of land surface reflectance (MOD09Q1) and LST (MOD11A2) derived from MODIS satellite data over Esfahan in the period of 2000-01(dry year) and 2004-05 (wet year) 8-day time step were used. Trend of soil moisture variations was evaluated using statistical methods such as Mann- Kendall, linear Regression and Wald- Wolfowitz in the 5 percent confident level. The results indicated that in the more than 40 percent of study area, there are no considerable variations in amount of soil moisture. The results showed also that Wald-Wolfowitz is not a suitable method for soil moisture routing in our area. The results indicated that in the western and central parts of study area, number of points with negative amount of moisture trend is increasing (from about 23% in dry year to 53% in wet year). It means that a long term trend of moisture declination and probably drought has occurred in the region. The points with positive trend in amount of soil moisture are limited only in the low eastern parts, Zayande roud river side and Gawkhoni swamp.