Showing 3 results for Percolation
S. Yousefi-Moghadam, S. F. Mousavi, B. Mostafazadeh-Fard, M. R. Yazdani, A. Hemmat,
Volume 16, Issue 60 (7-2012)
Abstract
Puddling is the most common method of land preparation for lowland rice cultivation. The purpose of this study was to assess the influence of various intensities of puddling on percolation rate, water retention by soil and the amount of water used for different puddling intensities in three dominant soil textures of paddy fields in Guilan province. Undisturbed soil samples were taken from 3 different soils including silty clay, clay loam and loam, with 3 replications. The soil samples were puddled by a laboratory apparatus with different intensities. The results showed that the low puddling intensity treatment caused a 29.3, 32.4 and 36% reduction of percolation rate in silty clay, silty loam and loam textures, respectively. Increasing puddling intensity from low to medium reduced percolation rate significantly, but high intensity was not effective. Soil moisture characteristic curves of all three soils showed that water retention was increased by puddling treatments. Water retention in silty clay was higher than the other two soils. The high intensity treatment needed more water than low intensity for puddling. Increasing puddling intensity from medium intensity to high intensity caused 15.4, 14.1 and 16.3% increase in the amount of water required for puddling in silty clay, silty loam and loam textures, respectively. Generally, in all the three studied soil textures, the amount of water used for high-intensity puddling was more than medium-intensity puddling, while it had no significant effect on water percolation rate and soil water retention.
S. M. Mousavi, A. Hoshmand, S. Bromandnasab, M. Yazdani,
Volume 16, Issue 60 (7-2012)
Abstract
The common method of irrigating rice in paddy fields of Iran, like most countries, is flooded irrigation. The water required in this method is too much. However, because of water shortage in recent years, and malfunctioning of irrigation systems, it is needed to use water in a reasonable way and increase water use efficiency. Therefore, it is necessary to know water loss amounts at the paddy fields. The deep percolation (DP) was measured by closed- and open-bottom rings in 4 locations, and 7 sites at each location, of paddy fields in Somae-Sara city, Guilan province. These locations were selected on the base of different physiographic units. The average DP of these locations was also monitored during plant growth season. The measurements were performed twice a week. Results showed that the rate of DP varied during the season, and could take a positive or negative value. The most important factors of these variations were the lateral seepage (from surrounding rice fields) and the high perched groundwater table in paddy fields.
Sh. Nasiri, N. Farrahi, A. N. Ziaei,
Volume 24, Issue 2 (7-2020)
Abstract
One of the most important and complex processes in the watersheds is the identification and prediction of surface water changes. The main processes associated with surface water include precipitation, percolation, evapotranspiration and runoff. In this research, the semi-distributed model, SWAT, was used to simulate ground water and surface water in Semnan catchment in a monthly scale. A sensitivity analysis was perfomed to evaluate and demonstrate the influence of the model parameters on the four major components of water budget including surface runoff, lateral flow, groundwater and evapotranspiration. River discharge data from 2004 to 2014 were used for the calibration and those of 2014 to 2016 were applied for the validation. The results of sensitivity analysis showed that the most sensitive parameters were: SoL_K(Saturated hydraulic conductivity), CH_K2 (Effective hydraulic conductivity in main channel), RCHRG_DP(Deep aquifer percolation fraction and CN2 (Moisture condition II curve number). The simulation accuracy using Nash-Sutcliffe and coefficient of determination for Shahrmirzad, Darjazin, and Haji Abad hydrometric stations was about 0.60 to 0.80 and 0.80 to 0.90 for the calibration and validation period, respectively, showing a good performance in the simulation of river flow. According to the water balance results, about 87.6% of the total inflow into the watershed was actual evapotranspiration, 3% was surface run off, 3% was percolation, and the rest was related to the soil moisture storage.
