Search

One of the important issues in river engineering is flood trends. In general, two types of methods are used to determine the flood trends in rivers. The first group of hydraulic methods, such as the dynamic wave method, is based on solving continuity and momentum equations or Saint-Venant equations. The second category is hydrological methods like the non-linear Muskingum method. In this research, both methods have been used to determine the trends of flood hydrographs in the Plasjan River, one of the main tributaries of the Zayandehrud River. The coefficients of the non-linear Muskingum method were obtained by optimizing and solving the related equation with the fourth-order Runge-Katai numerical method using MATLAB software and the dynamic wave method using the two-dimensional HEC-RAS software. In this study, four flood events were used. In the non-linear Muskingum method, the first event was used for model calibration and the other three events were used for validation. The error rate in this method for the second, third, and fourth events was 84.23, 6.6, and 7.96 percent, respectively, and the error rate in the dynamic wave method for these four events was 17.58, 87.3, 5.4, and 6.21 percent, respectively. Therefore, the dynamic wave method is more accurate in estimating the output hydrograph. However, the non-linear Muskingum method has acceptable accuracy and is recommended in terms of cost, required information, simplicity, and speed of calculation in situations where sufficient information is not available.

and water management in the field. Therefore, its measurement has special importance. The surface soil has a great diversity in soil moisture and different methods were used to measure this property. Due to the problems of contact methods of soil moisture measurement, remote sensing has gained attention because of the possibility of analyzing and monitoring soil moisture on a large and global scale. In this research, satellite data and moisture measured in selected fields located in Hormoaz Abad Plain have been analyzed and compared. Sentinel-2 satellite data have been analyzed using the Google Earth Engine system. The results of this research showed that the use of triple indices in the OPTRAM model to estimate moisture is not very accurate, but the use of the EVI plant index has provided better results than the other two indices.

Surface irrigation is one of the most common irrigation methods. Due to the low efficiency of surface irrigation, water loss is significant in this system. It is necessary to know the characteristics and coefficients of water infiltration rate in the soil for accurate and adequate planning of surface irrigation. One of the equations used in this field is Phillip's infiltration equation. In this study, the infiltration coefficients of Phillip's equation and Manning's roughness coefficient in border irrigation are determined based on the comparison of the actual advance curve with the advance curve calculated with the dynamic wave model, and the results were compared with the double cylinder method and the two-point method of Ebrahimian et al. (5). The actual infiltration volume was obtained from the difference between the inlet and outlet volumes. The error of the mentioned method in calculating the infiltration volume was 5.53%. Meanwhile, the errors in the double cylinder and two-point Ebrahimian (5) method were 59.62% and 19.08%, respectively. In heavy soils, the longer the length of the border increases, the method is more accurate in estimating Philip's coefficients, while in light soils, the advancing time, which in addition to length is a function of permeability, input discharge, and the slope of the bottom of the bed is increased, the accuracy of the method in estimating Philip's penetration coefficients is increased.