Numerical modeling of short term morphological changes around coastal structures and at the river mouths

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2016

Öğrenci: EBRU DEMİRCİ

Danışman: CÜNEYT BAYKAL

Özet:

In this study, XBeach, a two dimensional depth averaged numerical model developed mainly for simulating nearshore hydro- and morphodynamics is applied to two case studies; i) laboratory experiments on short-term morphological changes around a detached breakwater and a T-groin and ii) a fluvial dominated coastal flooding event at the Manavgat river mouth between dates, 4th and 15th December, 1998. In the first part of study, the numerical model is calibrated for the wave, current and bottom evolution conditions using the base experiment in which there are no structures. Later, the model is applied to the detached breakwater and T-groin experiments. It is observed that the numerical model results are in agreement with the measured wave heights and current velocities in the vicinity of structures, however the morphological changes are slightly underestimated. To investigate the scale dependency of numerical model, the laboratory data is scaled up using undistorted Froude scaling and the numerical model is applied to the scaled-up experiments. The results of latter simulations show that the morphological changes are represented better. In the second part of the study, a preliminary numerical modeling is carried out to investigate the capabilities of the numerical model in combined fluvial-coastal flood events. The numerical model is applied to a twelve day fluvial dominated coastal flooding event, in which the initial and final shorelines measured are compared with the model results. The river mouth has widened at the end of the simulation, as observed, and the eroded material is accreted in front of the river mouth forming a submerged sand bar. The final shoreline between the river mouth and the east jetty shows well agreement with the measured, whereas the wave induced erosion at the seaward edge of west side of the river mouth is underestimated.