عنوان مقاله [English]
Drought prediction for in many regions of the world has critical importance for strategic planning agriculture and water management. The occurrence of droughts cannot be predicted with certainty and thus must be treated as random variables. It is the main purpose of this paper to develop a new concept of drought features assessments based on triple drought related hydro meteorological and meteorological variables, namely, rainfall, solar irradiation and sunshine duration. At first scatter diagram of rainfall, solar irradiation and sunshine duration are drawn as named Dual Graphic Method (DGM) and observed monthly drought condition are change compare SMP values table. Equal standard rainfall lines are drawn as a map with two reference variables as solar irradiation and sunshine duration. These are referred to as the triple graphical method (TGM) approach. It furnishes rich features of drought behavior variation based on the rainfall, solar irradiation and sunshine duration. This analysis and the solar irradiation estimation method are applied to Kermanshah stations in the Republic of Iran for the monthly data period 1970–2010. The linear relations between drought and the variables of the Angstrom equation are found 0.61. TGM graphs help to identify not only precipitation surplus (wet spells) or deficits (dry spells droughts) but also their variations with two more meteorological variables as solar irradiation and sunshine duration.