Aquatic vegetation in rivers and coastal regions controls the flow structure in terms of mean velocity and turbulence. The vegetation in the flow affects the transportation of nutrients, microbes, dissolved oxygen, sediment, and contaminants; therefore, the flow characteristics of different types of vegetation layers should be examined in order to understand the effects of vegetation on the flow structure. In this paper, the effect of the submergence ratio and SVF (Solid Volume of Fraction) of a vegetation patch, which was present across half of the channel in a spanwise direction, on the flow structure at the wake region was examined. For this purpose, different submergence ratios with different SVFs were considered in the experiments, and velocity measurements were performed in the wake region of the vegetation layer with an Acoustic Doppler Velocimeter (ADV). According to the results, the effect of different vegetation heights and SVFs on the velocity distribution was obtained. Moreover, inflectional velocity distribution over the cross-section in the wake region of the vegetation layer was obtained, and it was concluded that jet flow occurred in the non-vegetated half of the channel due to the vegetation layer.

No abstract

Urban stormwater is an important environmental problem, especially for metropolitans worldwide. The most important issue behind this problem is the need to find green infrastructure solutions, which provide water treatment and retention. Floating treatment wetlands, which are porous patches that continue down from the free-surface with a gap between the patch and bed, are innovative instruments for nutrient management in lakes, ponds, and slow-flowing waters. Suspended cylindrical vegetation patches in open channels affect the flow dramatically, which causes a deviation from the logarithmic law. This study considered the velocity measurements along the flow depth, at the axis of the patch, and at the near-wake region of the canopy, for different submerged ratios with different patch porosities. The results of this experimental study provide a comprehensive picture of the effects of different submergence ratios and different porosities on the flow field at the near-wake region of the suspended vegetation patch. The flow field was described with velocity and turbulence distributions along the axis of the patch, both upstream and downstream of the vegetation patch. Mainly, it was found that suspended porous canopy patches with a certain range of densities (SVF20 and SVF36 corresponded to a high density of patches in this study) have considerable impacts on the flow structure, and to a lesser extent, individual patch elements also have a crucial role.

Özet Son 30 yılda ekosistem ve dünya için vazgeçilmez bir rolü olan bitki tarlalarının kıyı ve

The phenomenon of large volumes of currents resulting from excessive precipitation or snowmelt not fit in the river bed is called a flooding. Turkey, because of its geographical location, especially because of the impact of the Black Sea, Marmara, Aegean and Mediterranean sea is frequently observed rainfall, and the consequent loss of life and property is a country where occurs. In the flooding incidents experienced, it is seen that the major reason in the areas close to the settlements is mostly inappropriate and inadequate interventions to the river beds and wrong reconstruction practices. Zoning applications on the sandy areas where the rivers meet the sea and on the alluvial flats without considering the flood boundary cause many engineering problems. In this study, the effect of pouring into the sea was investigated in the Işıklar river, which is located in the coastal line of the Kumbağ district of Tekirdağ province and reaches the sea passing through the residential areas, and the water surface profile of the sunken hydraulic section was modeled with the help of the HEC-RAS (Hydrologic Engineering Center-River Analisis System) analysis program and the results were compared with the profile of the water face in the non-submerged hydraulic section. With the effect of submerged hydraulic section and water pouring into the sea, it was observed that the water surface profile decreased significantly in the sections close to the sea and it was also observed that this downward trend was effective until the inner parts.

In this study, the effect of submerged plants on open channel flow was modeled using Flow-3d. The model, was based on the experimental setup, built-in Aydın Adnan Menderes University, Engineering Faculty, Civil Engineering Department. The experimental and the model results were compared.

It has become increasingly important in recent years to study the effects of vegetation fields on the fluvial areas which are very important for the ecosystem. The water plant fields can be classified as submerged, emergent and suspended vegetation. The major difference of the suspended vegetation is the effect of the bottom boundary layer under the plant. Suspended vegetation is obstacle and will cause a decrease in speed of the flow and the vertical velocity distribution will deviate from the classical logarithmic distribution. Contrary the decrease in speed in the upper layer due to the plant, the speed increase will ocur in the gap beneath the plant. In this research, 181 rigid cylinders with a diameter of 1.0cm were fixed to a 30cm diameter wooden head and mounted on the upper side of the channel. The plant was allowed to enter into 15cm of water and there is a 15cm gap beneath the plant, between the channel bed and the plant end. An ADV (Acoustic Doppler Velocitymeter) was used to collect data from 11 different points (4 points before the plant and 7 points after the plant) and 8 different depths. Experimental results have shown that the suspended vegetation is a barrier to flow and affects the the velocity of the flow.