Mohammad Ghorbanian
Abstract
Many numerical and analytical models have been developed for estimation of soil water distribution in order to increase water use efficiency in drip irrigation. Accurate solution of well-known soil water equation, Richard’s equation, in these models cause more accurate estimation of soil wetting front. ...
Read More
Many numerical and analytical models have been developed for estimation of soil water distribution in order to increase water use efficiency in drip irrigation. Accurate solution of well-known soil water equation, Richard’s equation, in these models cause more accurate estimation of soil wetting front. The purpose of this study was to evaluate finite difference and finite element methods to numerical solution of Richard’s equation for simulating soil water flow around dripper via comparing HYDRUS-2D and SEEP/W numerical models. Experiments were carried out to collect required data to investigate the advance of moisture front inside a Plexiglas box filled with a silt loam soil in central laboratory of water researches in University of Tehran. Wetting front advance at different time intervals were plotted on the transparent Plexiglas box walls. The wetting front around the emitters, for pressures 1.5 and 2.2 meters (equivalent to 4.5 and 6.3 liters per hour, respectively), were measured. Comparison of two simulation models, HYDRUS-2DandSEEP/W, showed that HYDRUS-2D model (finite difference solution method) with higher determination coefficient and lower root mean square error coefficient had better performance to simulate wetted area dimensions for both surface and subsurface drip irrigation.
H. Asakereh; R. Khoshraftar; F. Sotudeh
Abstract
Rainfall and debit of rivers are two tempo-spatial non-linear and changeable factors. One way to study and analysis these parameters is investigate appearance and latent oscillations. Spectral Analysis is a useful technique to reveal these oscillations in time series. In this paper it has been attempted ...
Read More
Rainfall and debit of rivers are two tempo-spatial non-linear and changeable factors. One way to study and analysis these parameters is investigate appearance and latent oscillations. Spectral Analysis is a useful technique to reveal these oscillations in time series. In this paper it has been attempted to detect cycles in rainfall and debit time series at Mashinkhaneh station in Talesh (Garakanrood) catchment’s during Mehr 1354 to Shahrivar 1386 in the three time scales (annual, seasonal and monthly). Accordingly, the discharge and precipitation data at Mashinkhaneh station in Talesh (Garakanrood) catchment from Mehr 1354 to Shahrivar 1386 have been used. The results of applying the spectral analysis procedures to discharge and rainfall time series in each three category of time scales, suggested the absence of significant non-sinusoidal (trend) in the 95% confidence level. However, significantly sinusoidal cycles various in the two time series were extracted. The 2-4 year cycle, and 4-5.3 years have the most occurrences in the both time series. In the annual scale, 6.4 years cycle, 2-5.3 years, 7.7 years seasonal and 2-4, 4- 5.3, 6.4, 8, 10.7 and 16 year in the monthly scale cycles has been extracted. Studies carried out by many researchers indicate that the mentioned cycles are in relation with oscillation periods of ENSO, NAO and QBO in other parts of the world.
