Modeling of water flow in multi-channel river system in the Narew National Park

Abstract

Abstract:Modeling of water fl ow in multi-channel river system in the Narew National Park. Anastomosing rivers constitute a rare example of multi-channel systems, which used to be very common before the agricultural and industrial development. Presently few of them remain worldwide and the only example in Poland is the Upper River Narew within Narew National Park. Although hydraulic modeling using one-dimensional models is commonly used to describe water fl ow in rivers, for multi-channel rivers problem is more complicated. For this type of rivers it is expected that the feedback between process of plants growth (expressed by Manning's coeffi cient) and distribution of fl ow in anabranches is high. However, assignment procedure on roughness coeffi cients in splitting and rejoining channels is laborious and diffi cult. Therefore, for effi cient water fl ow modeling in multi-channel systems a stand-alone hydraulic model equipped with automatic optimization procedure was developed. Optimization and validation stages, based on fi eld measurements data of discharge and water levels, indicated that the model accurately simulates water fl ow in multi-channel system.

Model-Based Analysis of Macrophytes Role in the Flow Distribution in the Anastomosing River System

“…In anastomosing rivers, any flow blockage increasing water levels causes impoundment effect upstream to bifurcation node where the flow splits. Subsequently, according to Bernoulli's conservation equation (for details of use in MFRM, see Marcinkowski et al [65]), a certain volume of water is redirected from one channel (highly vegetated) to another (less vegetated). Therefore, flow distribution at each bifurcation in the anastomosing river depends on the channels geometry [72] and in-channel vegetation characteristics (e.g., height and density) determining their drag force [66].…”

“…Whilst in single channel systems this procedure is relatively simple and manually feasible, in complex interconnected system of channels it becomes difficult and laborious. While the full description of model setup, calibration and validation was presented in the study of Marcinkowski et al [65], here we provide a brief overview, important in the context of the main goal of this paper.…”

Modelling of climate change impact on flow conditions in the lowland anastomosing river

“…The geometric data consisted of river cross-sectional geometry collected at periodic, uniformly distributed (250 m intervals) stations along the selected, anabranching reach. The spacing of the measured cross-sections is related to Narew river topography (Marcinkowski, Kiczko & Okruszko, 2017). In the numerical model these cross-sections were used as a basic set for interpolating cross-section data at finer spacing.…”