The aim of research was to study the variability of evapotranspiration values and actual stored soil moisture for different hydrometeorological parameters with information database maintenance for operational management of irrigation process. Computational methods with which evapotranspiration is defined rather exactly on the results of actual observations including among others meteorological conditions in the area corresponding to the irrigated plots during the observation periods 1960–1980, 1990–2010 and 2012–2014, have been used. The potential evapotranspiration has been determined on the existing network of hydrometeorological and water balance stations for the years of research concerned and these data have been compared with the obtained values. Therefore, for operational planning and management of crops technological irrigation it’s necessary to know the actual value of stored soil moisture in the predicted soil layer at the beginning and end of the base period. Analysis of forty years of observations allowed the authors to establish empirical dependences of evapotranspiration and potential evapotranspiration on their modular coefficients using the correlation method. V. P. Ostapchik’s model on definition of potential evapotranspiration with the establishment of bioclimatic coefficients for each phase of growth and development of summer planting potato on floodplains of the Lower Don was adapted. Thus bioclimatic coefficients depending on the moisture reserves in the soil layer were calculated by vegetation phases of summer planting potato with the appropriate parameters, as follows: A1 – from minus 0.295 to minus 0.027; A2 – from 0.181 to 1.747; A0 – from 0.025 to 1.395. The approximating accuracy ranged from 0.92 to 0.98. As a result of V. P. Ostapchik’s formula modification the regional dependence in determining the potential evapotranspiration in a floodplain of the Lower Don with empirical coefficients A and b, equal to 1.220 and 0.003 respectively was determined.
Keywords: hydrometeorological parameters, evapotranspiration, potential evapotranspiration, irrigation, prediction, potatoes, floodplain soils.
