Numerical simulations in the Mala Nitra stream by 1D model

Abstract

abstract. The development of the computer technologies enables us to solve the ecological problems in water management practice very efficiently. Hydrodynamical models which simulating transport of pollution in surface water are very demanding on input data and calculation time, but on the other side, they are able to simulate detailed effect of dispersion in surface waters. The paper deals with 1-dimensional numerical model HEC-RAS and its response on various values of dispersion coefficient. This parameter is one of the most important input data for simulation of pollution spreading in streams. Getting fair value, however, is in practice very difficult. One option is the most accurate simulation of tracer experiments carried out on the ground on the natural surface flow. For the pilot application was selected flow Small Nitra. Of longitudinal dispersion coefficient in the flow, or the flow of a similar nature (with and limit the rate of flow), were in the range 0.05 to 2.5 m 2 · s -1. The next task was carrying out the model sensitivity analysis, which means to evaluate input data influences, especially longitudinal dispersion coefficient, on outputs computed by 1-dimensional simulation model HEC-RAS. Sensitivity analysis model HEC-RAS also showed its adequate response to changes of the input parameter. Given the present results it can be stated that the HEC-RAS model responds to changes in the values of the longitudinal dispersion coefficient appropriately. HEC-RAS model has demonstrated its applicability to simulation of pollution in streams, and therefore is an appropriate tool for decision making related to the quality of water resources.

Calibration of channel roughness in intermittent rivers using HEC-RAS model: case of Sarimsakli creek, Turkey

“…As shown in these values, HEC-RAS roughness parameters vary between 0.020 and 0.065 for six different flow conditions. A similar range of roughness was observed by other authors as well [2,19,30]. Average of the roughness coefficients determined by the HEC-RAS for six measurements is found as ≈ 0.045.…”

“…Among various channel's hydraulic parameters, the channel's roughness plays a crucial role in the study of open-channel flow, particularly in the hydraulic modelling of natural rivers. Channel roughness of the natural rivers it varies among cross-sections and along the longitudinal direction of the river [1,2]. It changes in space and time and depends upon some factors like; river bed geomorphology, vegetation cover, channel's local irregularities and alignment [3,4].…”

The Urban Environment Impact of Climate Change Study and Proposal of the City Micro-Environment Improvement

“…In the given locality, it was possible to use water infiltration as a solution. At the locality [60] there are suitable conditions of land ownership, pedological conditions, the slope of the territory and also the interest of the inhabitants in the ecological solution. Soil for infiltration has borderline properties for infiltration, but as a detention-infiltration solution, rainwater management is possible.…”

Determination of the Longitudinal Dispersion Coefficient in Lowland Streams with Occurrence of Dead Zones

“…We believe that the determination method of this key parameter should be in accordance with the method of use of a particular model or method to achieve maximum conformity, e.g. (Halaj et al 2013;Szomorová, Halaj 2015). Such an approach would require in most cases to perform tracer experiment and determination of the dispersion coefficient with regards of the future model use.…”