Usually the energy balance equation is used to estimate evapotranspiration. To calculating the potential evapotranspiration for long periods of time (more than a day), soil heat flux is assumed equal to zero. But in a catchment, the energy balance equation should be in terms of actual evapotranspiration is less than the potential. In this state, the amount of soil heat flux is not equal to zero...

The rise in water demand for agriculture, industry, domestic, and environmental needs requires sagacious use of this limited resource. Since agriculture (mainly irrigation) is the major user of water, improving agricultural water management is essential. Efficient agricultural water management requires reliable estimation of crop water requirement (evapotranspiration). Evapotranspiration (ET) i...

This paper examines the impacts of three different potential evapotranspiration (PET) models on drought severity and frequencies indicated by standardized precipitation index (SPEI). The precipitation-evapotranspiration is a recent approach to operational monitoring analysis severity. combines temperature data, quantifying as difference in timestep between PET. thus represents hydrological proc...

The Everglades in south Florida is a marsh system where most of the time wet vegetated marshes and open water features prevail. Rainfall and evapotranspiration (ET) are the main parameters in the hydrology of the Everglades. The delicate balance between rainfall and evapotranspiration maintains the hydrology system in either a wet condition or dry condition. Based on a literature review of both...

A basic problem relating to the long-term water balance involves splitting precipitation P, into runoff R, and actual evapotranspiration E. Berger and Entekhabi (2001) showed that the evapotranspiration efficiency E/Ep (Ep denotes potential evapotranspiration) and the runoff ratio R/P, are related to physiographic basin features and regional climate information. Berger and Entekhabi (2001) esti...

[1] An important factor controlling catchment-scale water balance is the seasonal variation of climate. The aim of this study is to investigate the effect of the seasonal distributions of water and energy, and their interactions with the soil moisture store, on mean annual water balance in Australia at catchment scales using a stochastic model of soil moisture balance with seasonally varying fo...

Available energy (often expressed in terms of potential evaporation) and precipitation largely determine annual evapotranspiration and runoff rates in a region. The ratio of annual potential evaporation to precipitation, referred to as the aridity index by Budyko, has been shown to describe the evaporation ratio (the ratio of annual evapotranspiration to precipitation) of catchments from a rang...

Climate change due to increasing the concentration of greenhouse gases (especially CO2) in the atmosphere causes changes in the rainfall regime, runoff rate, wind speed and solar radiation of atmosphere. In the present research, the maximum and minimum temperature parameters were simulated during the base period of 1979-2088 and two future periods of 1979-2070 and 2070-2090 using daily ...