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The Hydrological Tank model was used in this study to simulate the rainfall-runoff relationship in the Flint River basin near Carsonville, Georgia, USA. The model’s structure consisted of two tanks (upper and lower), and it depended primarily on a set of eight parameters to simulate daily stream flow components (surface, subsurface, and base flows) from daily precipitation while taking into account the effects of daily evapotranspiration, the water storage height, and the infiltration rate. The parameter set was calibrated, optimized, and validated with data spanning a period of 10 years (Oct. 1st, 2007–Sep. 30th, 2017). Model calibration and validation were performed by using the first and second 5-year periods of water flow data, respectively. The model performance was verified using the coefficient of determination (R2) and the Nash–Sutcliffe efficiency (NSE) coefficient. The results of one- and two-parameter sensitivity analyses showed that the model performance was highly dependent on the parameters Ko and K1 (the coefficients of the surface and subsurface flows, respectively). The Downhill Simplex Method (DSM) was used to find the optimum parameter set via the maximization of R2 and NSE. The optimum parameter set produced by maximizing the NSE values was adopted in this study because it produced a very good correlation between the simulated and observed stream flows for both the calibration and validation time periods. Using the adopted optimum parameter set, the maximum values of R2 and NSE were 0.818 and 0.812 in the calibration time period, respectively, and 0.756 and 0.750 in the validation time period, respectively. Moreover, the DSM has proven to be very reliable in locating global optimums and requires reasonable computational efforts in the calibration of a hydrological model.

Composite hydraulic structure is widely used in irrigation system which consists of two parts. The first part is responsible for overflow regime and is represented by a weir, whereas the second part is responsible for underflow regime and is represented by a gate. Both elements play significant role to control, measured, and divert the flow. So it dominates the hydraulic regimes of open channel or river with high responsibility and accuracy. The target of this study is to investigate the effect of the composite hydraulic structure installation at various inclination angles (from 45-135 degree) with the flume bed, which is horizontal, and adopt the normal position of composite device ( angle equal to 90 degree) as guide in discussion with various angles. Several experimental works were carried out in hydraulic laboratory flume at the Basrah Engineering Technical College under free flow condition with various geometrical dimensions of combined rectangular weir and rectangular gate in order to investigate the effect of inclination angle on major flow factors such as actual discharge, discharge coefficient, depth of water in downstream zone of flume, cross sectional area of flow that cross or pass the weir and gate respectively. Also, this study mentions the percentage of increase in discharge coefficient and variation in actual discharge, discharge coefficient and Reynolds Number with cross sectional area of flow that cross the gate.

A set of laboratory experiments were conducted to study the impact of vegetation on bed form resistance and bed load transport in a mobile bed channel. Vegetation stems were simulated by using arrays of emergent polyvinyl chloride (PVC) rods in several staggered configurations. The total flow resistance was divided into bed, sidewall, and vegetation resistances. Bed resistance was further separated into grain and bed form (i.e., ripples and dunes) resistances. By analyzing experimental data using the downhill simplex method (DSM), we derived new empirical relations for predicting bed form resistance and the bed load transport rate in a vegetated channel. Bed form resistance increases with vegetation concentration, and the bed load transport rate reduces with vegetation concentration. However, these conclusions are obtained by using experimental data from this study as well as others available in the literature for a vegetated channel at low concentration.

A set of laboratory experiments were conducted to study the effect of using a Strip Guide Flow Panel device to reduce scour process effects around a bridge pier. Three cylindrical piers of different diameter values and three different Strip Guide Flow Panel devices were used. Every Strip Guide Flow Panel device is simulated by two arms connected together at one of their edges at a right angle. The length of every arm is selected in a way to cover the pier diameter. Every Strip Guide Flow Panel was mounted on the upstream face of the corresponding cylindrical pier diameter at elevation adjacent to the flume bed. A uniform sized sediment were used as a bed material. Based on the experimental data, an acceptable range of scour reduction efficiency (35.71-66.67%) and high hydraulic safety factors were obtained when using Strip Guide Flow Panel. Also it is found that the scour depth when using Strip Guide Flow Panel is small comparing with corresponding potential and maximum scour depth values. So it can be concluded that the Strip Guide Flow Panel device can work like a turbulence kinetic energy dissipater to reduce the risk of scour around the pier during the serviceability life of bridge structure.

or a long time, Iraq has been suffering from environmental pollution and electricity crisis. Therefore, tidal energy is one of the best renewable sources should be used to solve together the environmental pollution and electricity crisis. Tidal energy is usually available in coastal areas. Southern of Iraq has coastal areas in Basra Governorate on the northern Arabian Gulf. Therefore, this study has been investigated the possibility of establishing tidal power stations in two locations in Basra, Um Qasr and Al-Faw. In the case of the construction of a 4km2 tidal barrage in Um Qasr, the electricity generated was 98.85MW and 197.69MW to meet the demand for electricity in Basra by 6.59% and 13.18% in the case of one-way and two-way generation, respectively. While in case of construction of a 4km2 tidal lagoon in Al-Faw, the electricity generated was 31.37MW and 62.73MW to meet the demand for electricity in Basra by 2.09% and 4.18% in the case of one-way and two-way generation, respectively. So, this study clearly shows that tidal energy can contribute significantly to relief the electricity crisis in Basra Governorate.

A Delft3D-FLOW model was used to simulate tidal flow in Davis pond marsh in Louisiana, USA. The study area is a freshwater marsh consisting of one main channel and floodplain. Vegetation-induced flow resistance greatly influences tidal flow dynamics in the marsh. This study evaluated eight approaches to estimate vegetation roughness, including two constant Manning's n values, four empirical relations for calculating n, and two methods for calculating Chezy's C values originally embedded in the Delft3D model. Simulated results of water surface elevation (WSE) were compared with the corresponding field observation at eleven stream gauges in the study area. We concluded that the roughness coefficient for vegetated area varies with time as flow depth changes. Among the selected empirical relations for the vegetation roughness, the ones accounting for the effect of the vegetation frontal area and the degree of submergence have closely matched the measurements.

For a long time, Iraq has been suffering from environmental pollution and electricity crisis. Therefore, tidal energy is one of the best renewable sources should be used to solve together the environmental pollution and electricity crisis. Tidal energy is usually available in coastal areas. Southern of Iraq has coastal areas in Basra Governorate on the northern Arabian Gulf. Therefore, this study has been investigated the possibility of establishing tidal power stations in two locations in Basra, Um Qasr and Al-Faw. In the case of the construction of a 4km2 tidal barrage in Um Qasr, the electricity generated was 98.85MW and 197.69MW to meet the demand for electricity in Basra by 6.59% and 13.18% in the case of one-way and two-way generation, respectively. While in case of construction of a 4km2 tidal lagoon in Al-Faw, the electricity generated was 31.37MW and 62.73MW to meet the demand for electricity in Basra by 2.09% and 4.18% in the case of one-way and two way generation, respectively. So, this study clearly shows that tidal energy can contribute significantly to relief the electricity crisis in Basra Governorate.

The importance of numerical schemes in hydrological models has been increasingly recognized in the hydrological community. However, the relationship between model performance and the properties of numerical schemes remains unclear. In this study, we employed two types of numerical schemes (i.e., explicit Runge-Kutta schemes with different orders of accuracy and partially implicit Euler schemes with different implicit factors) in the hydrological model (HYMOD) to simulate the flow hydrograph of the Leaf River basin from 1948 to 1988. Results computed by different numerical schemes were compared and the relationships between model performance and two scheme properties (i.e., the order of accuracy and the implicit factor) were discussed. Results showed that the more explicit schemes generally lead to the overestimation of flow hydrographs, whereas the more implicit schemes lead to underestimation. In addition, the numerical error tended to decrease with increasing orders of accuracy. As a result, the optimal parameter sets found by low-order schemes significantly deviated from those found by the analytical solution. The findings of this study can provide useful implications for designing suitable numerical schemes for hydrological models.