The concept of armouring is used to discuss the coarse surface layer in RIVERs. Selective erosion in an alluvial channel reach for which there is no upstream sediment supply can lead to formation of a layer coarser than the under laying material. This phenomenon inhibits sediment transport from the reach.Numerical modeling of armouring RIVER BED, provides an approach to simulation of this phenomenon, however, these models are complicated in application. In addition, discretisation errors, affect the solution. Herein this paper, an analyticalbased model has been developed; it is a simple one layer, 1- D, model to analysis different parameters in development of an armour layer, to predict depth of erosion and BED gradation curve of an armour BED. Differential equations describing armouring process, have been solved analytically, for each time step. The time steps are selected small enough to solve the equations analytically, for uniform flow, by avoiding discretisation errors.Predicted results are then compared by experimental data and numerical model results. This has shown reasonable validation of the model.

Information on erosion and capacity of sediment carrying condition in various basins is one of the subjects that in each of hydrology and RIVER engineering projects should be considered. In the present study HEC- RAS model was applied to evaluate and predict the sedimentation and erosion in the reach of Talar RIVER with 12 km length. For doing this study 40 cross section which was surveyed in 2006 is applied in the simulation and 4 cross section which was surveyed in 2011 applied for calibration of the model. Model calibration and verification showed that the Meyer Peter Muller sediment transport equation has a better fit with the observed results. In order to predict the erosion and sedimentation trend, using recorded data of dischrges in Shirgah hydrometric station during last 30 years and using SAMS Statistical model, the amounts of monthly stream flow was predicted for the next 10 years and then sedimentation model was executed. Variations in the longitudinal profile of RIVER in all profiles showed that the most changes will occurs within the middle reach area and the beginning of the RIVER reach with the length of about 1000m and with having the mild slope is stable. Also predicted amount of sediment outflow from the studied reach is about 348534 tones for the next 10 years.

1. Introduction; Researchers have suggested different equations for RIVER bank profile, such as trigonometric, parabolic, exponential equations, etc [1]. In this research, a laboratory study has been conducted in a straight reach of sand-BED RIVER in order to validate ten types of RIVER bank profile equations. For this purpose, several stable channel geometry and especially experimental observations for channel bank shapes were compared with theoretical bank profiles and then the mean standard error of each equation was calculated and according to the results the closer ones were identified.

Variability analysis of RIVER sediment transport in different temporal and hydrological conditions is important in hydraulics and hydrological science and engineering. Otherwise, behavior analyzing of the RIVERian systems at the different temporal conditions is necessary in managerial decisions to control and reduce sediment transport. However, knowledge about the type and amount of sediment in watersheds in various temporal and hydrological conditions is limited. Therefore, this study aimed to investigate the variability of BED and suspended load and BED to suspended load ratio. The 6-years period (1998-2003) data of BED and suspended load (g l-1) and discharge (m3 s-1) were collected from Yazdekan station of Qotour Chay RIVER. The analyses also were carried out in Excel 2007 software. The results indicate that discharge increasing caused that the suspended load was increased and the BED to suspended load ratio was decreased at all seasons. As well, the lowest and highest BED and suspended load transport were occurred at the winter and spring, respectively. Amounts of minimum, maximum and median BED to suspended load ratio at spring, summer, autumn and winter were 5.02, 563.99 and 27.34%; and 0.075, 2034.91 and 135.80%; and 28.31, 659.15 and 184.94%; and 28.96, 457.61 and 169%, respectively. Also, during the study period the BED to suspended load ratio was varied about 0.7 up to 2034%. Therefore, using indirect methods to estimate sediment is not accurate because of complex behavior of sediment particularly BED load and BED to suspended load ratio with discharge. By and large, it is necessary that daily BED load measuring in sediment gauges.

The type of RIVERs are dry or seasonal in arid or semiarid zone and current flowing through them is short or if there is no flow. One of the best methods to divert the flow in the RIVER basin system is implementation with subsurface drainage network in the RIVER BED A laboratory model for study the effects of hydraulic and geometric characteristics of the intake flow rate diversion was designed, Which the possibility measuring the inflow and outflow of diversion was considered.in this study were evaluated the effect of BED slope intake and diameter size of particle on diversion flow in two condition, water level constant and without control input discharge. The results showed that the slope of the porous medium tangible impact on current of deviation is in a state of constant water level. But the steep increase in input mode increases the deviation is negligible in Dubai. The 20% increase in diameter drains, in case the input of 9% and 20% in fixed alignment surface water drainage flow improves.The SPSS were using to obtain an equations that by them can estimate the diversion flow base of head flow hydraulic conductivity in porous media.

This paper presents, a set of experiments was conducted in a Plexiglas flume setup to investigate the simultaneous use of pipe and blade in the scour control around a submerged pipe. A vertical cylindrical pipe with and without a blade placed below it was selected for the experiments. The experiments were carried out in two different sates: with blade and without blade the pipe. Moreover, they were performed for four different pipe diameters, flow intensities, and blades where clear water was also used. The results showed for all states that simultaneous installation of pipe and blade below it caused a substantial decrease in the scour length. In other words, applying the blade produced a decrease in the scour length below the pipe by 21 percent. Furthermore, in all states, simultaneous use of pipe and blade engendered a more increased scour depth than the absence of the blade, by 22 percent. Besides, maximum scour depth for simultaneous use of pipe and blade was obtained equal to 55 percent when the blade width, pipe diameter, and Froude number were set to 1. 24, 4. 8 cm, and 0. 42, respectively.

Determining the exact value of BED load is concerned with investigators. In this study the performance of 13 BED load sediment transport formula developed for use in steep gravel-BEDded armored ChehelChay RIVER, Iran is tested. The formulas are applied in the manner intended by the original authors. The results have been expressed in terms of a discrepancy ratio (r) defined as the ratio of the predicted and measured transport rate. The method of Ackers and White yields the best results for field data with 64% of the predicted transport rates in the range of 0.5£r≤2. The Meyer-Peter and Mueller and Van Rijn equations yields approximately good results with 43%, and 36% of the predicted transport rates within a factor 2 of the measured values, respectively.

Biological methods are applied to protect RIVER banks against waves. There are several biological plants grown nearby banks naturally and artificially that reed is the most common. Plants can damp the wave energy and as a result, they stabilize the RIVER banks and slopes. In the present paper based on the experimental studies and dimensional analysis, a parametric model is derived for the wave damping by reed and transmission. To evaluate parameters of the developed model, an experimental study has been carried out. A flume with 8 meters length, 50 cm width and the height of 80 cm was constructed at the Hydraulic Laboratory of Shahid Chamran University (SCU), Iran. Along the flume, a suitable small area was considered for the plant with different populations. More than 80 experiments were conducted and in each experiment waves with 1m, 1.5m, 2m, 3m and 3.5m wave length were produced by and appropriate means. Based on results of the dimensional analysis and the experimental study a model is presented model is in a very good agreement with observed data. This study shows that when the BED length of the biological (reed) protection is increase the transmission coefficient will decrease nonlinealy.

Unequal RIVER BED level at the RIVER junctions are common in nature. The study of scour and sedimentation at such junctions however have not received the attention of researchers because of the complexity of the experimental setup. In many studies it has been assumed that the BED level has no significant effect on the scour and sedimentation patterns. It has been reported by a few investigators that the flow patterns and the zone of maximum shear stress in junction of unequal BED level is different from that of equal BED level cases. This study investigated the effect of this variable. First the general non-dimensional equations were developed using the dimensional analysis. Many experimental tests were then conducted under three different RIVER BED discordances and different hydraulic conditions. The data from these experimental tests was compared with the results of the previous study. The results indicated that generally as the RIVER BED discordance increases, the scour hole and point bar dimensions decreases. Using the experimental data, the effects of each non-dimensional parameter on scour depth were investigated and finally relations were developed for prediction of scour dimensions.

The RIVER is a dynamic phenomenon that is constantly changing. Estimating the resistance of sediment particles against erosion will identify stable and unstable points in different areas of the BED. Study area of this research was of Masiel Mouchan RIVER in the Astaneh city. In this study, we investigated threshold of (transformation and deposition of BED sediments, in 4 cross sections. the critical shear stresses and the critical unit discharge calculated for four particle sizes D16, D50, D84 and D95 in all sections, and results shows, sediments in D16, D50, D84 and D95 diameter moves at bankfull discharge in sections 2 and 4, therefore sedimentary conditions of the RIVER BED will change at bankfull discharge. At cross sections 1 and 3, particles with a diameter of D84, D95 will remain stable in BED, and other particles smaller than this size was unstable. Sediment particle are unstable in cross section of 2 and 4, because Slope of cross sections 2 and 4 are greater than 1 and 3 cross section. Finally, the results of both methods (critical shear stresses and the critical unit discharge) have high confection and confirms these methods are useful for stabilization studies in other RIVERs.