Açık kanalda batmış bitkinin akıma etkisi

Abstract

Son 30 yılda ekosistem ve dünya için vazgeçilmez bir rolü olan bitki tarlalarının kıyı ve akarsu hidroliği üzerindeki etkilerini incelemek çok önem kazanmıştır. Akım ve bitki örtüsü arasındaki girişim, katı madde taşınımını, akarsu jeomorfolojisini ve akarsu bölgesindeki yaşam alanını önemli derecede etkilemektedir. Doğal bitki tarlalarının şüphesiz en önemli özelliği rastgele bir karaktere sahip olmalarıdır. Doğal bir bitki alanında, bitkinin yüksekliği, çapı, şekli, bükülme sertliği ve mekânsal dağılım gibi birçok parametre rastgele olarak olaya etkili olmaktadır [2]. Bu nedenlerden dolayı, akım alanı ve bitki örtüsü arasında meydana gelen etkileşimin anlaşılması akarsu düzenlemeleri ve akım kontrol durumları için oldukça önemlidir. Bu çalışmada, kısmi bitki örtüsüne sahip akarsularda bulunan batık bitki örtüsü ve akım arasındaki etkileşim deneysel olarak incelenmiştir. Deneylerde, düşük ve yüksek yoğunlukta (N1=172 IP/m² ve N2=1142 IP/m²) olmak üzere iki farklı bitki yoğunluğu kullanılmıştır. Kanalda x ekseni yönünde (13 farklı noktada), yanal mesafelerde (11 farklı noktada) ADV (Acoustic Doppler Velocimeter) ile üç farklı derinlikte düşey hız ölçümleri yapılmıştır. Bu çalışmada bitki tabakasının varlığının, akımın hızında bir azalmaya neden olduğu ve bitki yoğunluğunun artışıyla beraber hızdaki azalmanın daha etkin bir hale geldiği görülmüştür. Bu çalışmanın, literatürde art-iz bölgesi ile ilgili sınırlı sayıda olan çalışmalara katkı sağlayacağı düşünülmektedir.

Keywords

• : Bitki parçası,art-iz bölgesi,batık bitki

The effect of submerged vegetation on the open channel flow

Abstract

In the last 30 years, it has become very important to examine the effects of vegetation fields on the coastal and fluvial areas, which have an indispensable role for the ecosystem and the world. The interference between current and vegetation greatly affects the sediment transport, river geomorphology and habitat in the river area. Doubtlessly, one of the most important features of natural vegetation fields is the randomness. In a natural vegetation field, many parameters such as the diameter and height of the plants, their shape, bending stiffness and spatial distribution can be observed as random parameters [2]. For these reasons the interaction between flow and vegetation should be understand very well in terms of river management and flow control. In this study, interaction between submerged vegetation layer and flow at partially vegetated river flows was investigated experimentally. Rare and dense vegetation intensity (N1=172 IP/m² and N2=1142 IP/m²) was considered in the experiments. Velocity measurements were made at three different depths in the channel x-axis direction (at 13 points) and y-axis direction (at 11 points) using ADV (Acoustic Doppler Velocimeter). In this study, it was observed that the presence of the plant caused a decrease in the current speed and with the increase of the plant density, the reduction in speed became more pronounced. It is assumed that this study will contribute to the understanding of wake region.

Keywords

• Vegetation patch,wake region,submerged vegetation

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