Backwater Effect of Tidal Water Level Fluctuation and Riverine Discharge in An Idealized River

Abstract

Rivers debouching into the sea are subjected to tidal variation at the river mouth. Tide- river interaction can cause variations in discharge by giving an additional gradient in water level which known as a backwater effect and somehow can cause serious flood event. The main purposes for this paper are to determine the effect of backwater on the river under steady flow and flood condition. Hydrodynamic model was believed has the capabilities to simulate the behaviour of tide and flood coming from the river upstream. Numerical simulation of backwater effect due to riverine discharge into the open sea shows that significant backwater effect can be observed landward up to the point where the channel bed rises above the mean sea level. Tidal effect dominates in this lower reaches, whereas riverine peak discharge tends only to increase the water level in the upper reaches. The simple, idealized tide-river model reproduces the hydraulic of low land river well and can be extended to investigate the full range of tide and river flow to generalize the effect for backwater prediction.

Interactive Contribution of Indian Summer Monsoon and Western North Pacific Monsoon to Water Level and Terrestrial Water Storage in the Mekong Basin

“…The WL presented obvious annual periodic changes due to the seasonal precipitation and even monsoon activities [13]. Periodic changes were accompanied by small diurnal fluctuations, which are mainly caused by dominant semi-diurnal ocean tides in the southern SCS [49,50]. For Can Tho and My Thuan, which are closer to the coast, the backwater from the ocean intrudes into the estuary, which should dampen the amplitude of the WL [49].…”

“…In this study, after quantifying the contributions of two monsoon indices (i.e., the ISM index and WNPM index) using three RI methods, the ENSO effect was further discussed by introducing the MEI index into the analysis. However, other potential influencing factors (e.g., ocean tides on WL [49,50,77], precipitation and evapotranspiration on TWS) and the restriction of the number of valid factors on RI analysis remain unexplored. Furthermore, we mainly studied the interannual variance (i.e., 3-year and 5-year cycles) of monsoons with regard to the WL and TWS.…”

Modified geomorphic flood index (GFI) method on backwater problem in tidal tropical river for rapid flood assessment

“…Rivers debouching into the sea are subjected to tidal variations downstream of the river. Tides and rivers have different gradients in water level, and this interaction can cause variations in discharge, which can occur and likely cause serious flood events in the nearby region [15]. Coastal backwaters occurred because of the increase in sea level, which triggered an upstream propagation of flood waves and the reduction of spatial and temporal water stage fluctuations [16].…”