The Relationship between Rainfall and Soil Moisture

Abstract

Soil Water content plays an important role in global hydrological cycles and regional climate of development weather patterns, plus its take part on production of precipitation and climate change. The aim of this research is to find out, influence of Rainfall on Soil Water Content in Iraq during 31 years at months (October, November, December, January, February, March, April and May).Work was carried out with the monthly data of temperature and soil water content taken from (ECMWF), specifically model (ERA-Interim) for the period from 1979 to 2009 through the use of statistical techniques such as simple linear regression and correlation coefficient. The results showed that the highest value of the total rainfall recorded in Mosul at March, while in Basrah and Baghdad has recorded the greatest value to the total rainfall at January, and the variability in Rutba at November and February. Pearson test showed there is an moderate to high positive relationship in (Baghdad, Basrah) at months (November, December, January and February), Except Basrah there are no linear relationship at November , when rainfall increasing will be increase the volumetric soil water content and this is evident from the values slope and values of the correlation coefficient. In the months (October, March, April and May), there is no linear relationship between volumetric soil water content and total rainfall. But in Mosul and Rutba has recorded the highest values of the correlation coefficients were of medium to high valuesfor all months, except March in Mosul and (November , May) in Rutba, there is no linear relationship. volumetric soil water content depends on the amount of rainfall and the intensity of evaporation as well as the nomination, since the heavy rainfall may cause significant increase in the volumetric soil water content and extends this effect to the months that followed, therefore, the heavy rainfall helps to recharge ground water and increase the flow of running water.