Gergely Ámon

58502878000

Publications - 6

Comparing Depth-Integrated Models to Compute Overland Flow in Steep-Sloped Watersheds

Katalin Bene Gergely Ámon R. P. Ray

Publication Name: Hydrology

Publication Date: 2025-04-01

Volume: 12

Issue: 4

Page Range: Unknown

Description:

On steep-sloped watersheds, high-intensity, short-duration rainfall events are the leading causes of flash floods. Typical overland flow analysis assumes sheet-like flow with a shallow water depth. However, the natural creek beds in steep watersheds produce complex and intense flows with a shallow depth and high velocity. According to the hydrodynamical modeling processes for open channel turbulent flow, calculating rainfall-induced overland flow becomes a complex task. Steep topography requires a highly refined numerical mesh, which demands a more complex simulation process. Depth-integrated models with distributed parameters provide useful methods to capture the behavior of steep watersheds. This study investigates the watershed’s overland flow behavior by varying turbulent flow parameters and monitoring possible model errors. The refined modeling places a heavy demand on numerical solvers used for simulating the overland flow motion. This paper examines different depth-integrated model solvers applied to artificial watersheds and compares results produced by the different solver types. This study found that the Shallow Water Equation solutions produced the most consistent and stable results, with the Local Inertia Approximation solutions performing adequately. Adding Large Eddy Simulation to these solutions tended to overcomplicate Shallow Water solutions but generally improved Large Eddy solutions. The Diffuse Wave Equation solutions produced erratic results, losing stability and accuracy as watershed slopes steepened and flow paths became complex.

Open Access: Yes

DOI: 10.3390/hydrology12040067

Improving Flash Flood Hydrodynamic Simulations by Integrating Leaf Litter and Interception Processes in Steep-Sloped Natural Watersheds

Péter Kalicz Zoltán Gribovszki Katalin Bene Gergely Ámon R. P. Ray

Publication Name: Water Switzerland

Publication Date: 2024-03-01

Volume: 16

Issue: 5

Page Range: Unknown

Description:

More frequent high-intensity, short-duration rainfall events increase the risk of flash floods on steeply sloped watersheds. Where measured data are unavailable, numerical models emerge as valuable tools for predicting flash floods. Recent applications of various hydrological and hydrodynamic models to predict overland flow have highlighted the need for improved representations of the complex flow processes that are inherent in flash floods. This study aimed to identify an optimal modeling approach for characterizing leaf litter losses during flash floods. At a gauged watershed in the Hidegvíz Valley in Hungary, a physical-based model was calibrated using two distinct rainfall–runoff events. Two modeling methodologies were implemented, integrating canopy interception and leaf litter storage, to understand their contributions during flash flood events. The results from the model’s calibration demonstrated this approach’s effectiveness in determining the impact of leaf litter on steep-sloped watersheds. Soil parameters can estimate the behavior of leaf litter during flash flood events. In this study, hydraulic conductivity and initial water content emerged as critical factors for effective parametrization. The findings underscore the potential of a hydrodynamic model to explore the relationship between leaf litter and flash flood events, providing a framework for future studies in watershed management and risk-mitigation strategies.

Open Access: Yes

DOI: 10.3390/w16050750

Importance of Eddy Viscosity and Advection in Hydrodynamical Models for Simulating Flash Floods on Steep Sloped Watersheds

Katalin Bene Gergely Ámon

Publication Name: Chemical Engineering Transactions

Publication Date: 2024-01-01

Volume: 114

Issue: Unknown

Page Range: 805-810

Description:

Flash floods in steeply sloped watersheds pose significant human life and infrastructure. Accurate prediction of these events relies on key parameters such as peak flow, time to peak flow, and the total overland flow volume. Numerical models are highly effective tools for predicting flash floods. The accuracy of hydrodynamic models is determined mainly by the solver equations used. Depth-integrated models offer various equation sets, with the full hydrodynamic equation providing the most detailed, though computationally intensive, solution. Eddy viscosity is another critical factor in simulating turbulent overland flow. Still, increased equation complexity leads to longer computational times and the need for smaller time steps to maintain model stability. Simulating turbulent overland flow in steep watersheds is particularly challenging because maintaining stability in these conditions is difficult. This study examined overland flow using artificial watersheds and model rainfall events, testing multiple solvers within the Hydrologic Engineering Center – River Analysis System (HEC-RAS). By keeping geometry, mesh, and rainfall inputs consistent, the study compared solver performance, identifying potential errors that arise under different conditions. Nonlinear advection, rather than gravity and roughness, was found to govern flow around obstructions. These findings are critical for improving the reliability of models that simulate the complex dynamics of flash floods, ultimately aiding in the reduction of risks posed by these hazardous events.

Open Access: Yes

DOI: 10.3303/CET24114135

Enhancing Stormwater Management in Érd, Hungary, through Nature-Based Solutions for Sustainability and Resilience

Katalin Bene Attila Kálmán Gergely Ámon Csaba Szél

Publication Name: Chemical Engineering Transactions

Publication Date: 2024-01-01

Volume: 114

Issue: Unknown

Page Range: 1027-1032

Description:

Traditionally, stormwater management strategies were designed to evacuate water swiftly and efficiently to mitigate flood risks. However, water conservation has become a crucial concern with growing environmental awareness, raising damage costs due to climate change and sustainability goals. Urban stormwater capture and utilization are essential for maintaining soil moisture levels, irrigating green spaces, reducing urban heat islands, supporting diverse wildlife, fostering ecological balance, and improving living conditions. This study focuses on a dynamically growing Hungarian city, Érd, with rapidly changing land use and utilizes the numerical Storm Water Management Model to simulate various water resources management scenarios. The simulations revealed multiple vulnerabilities in the channel network, leading to a comprehensive reevaluation and redesign. This redesign integrates nature-based solutions, enhancing the system's effectiveness and climate resilience with limited territorial possibilities. By comparing various design approaches, this research demonstrates that incorporating nature-based infrastructure at residential and subwatershed levels substantially improves flood mitigation and increases precipitation retention capabilities, making traditional infrastructure developments unnecessary. The findings underscore the need for innovative, adaptive infrastructure solutions. Implementing nature-based solutions mitigates flooding and contributes to resilient, sustainable urban water management systems that are better prepared to handle the challenges of a changing climate. This study underscores the critical importance of innovative infrastructure solutions and the positive benefits of nature-based solutions in fostering resilient and climate-adaptive urban water management systems in cities with small open spaces, rapid population growth, and scarce financial resources.

Open Access: Yes

DOI: 10.3303/CET24114172

Rainfall duration and parameter sensitivity on flash-flood at a steep watershed

Katalin Bene Gergely Ámon

Publication Name: Pollack Periodica

Publication Date: 2023-07-11

Volume: 18

Issue: 2

Page Range: 54-59

Description:

The common feature of streams in steep sloping watersheds is that there is a significant change from base-flow to flash-flood; sometimes two or three orders of magnitude. In Hungary, these streams are usually ungauged, with lack of available data, and models. The watershed features both urban and natural land use conditions, but the main area is quite homogenic. This paper evaluates the impact of different model parameterizations, and rainfall duration on flash-flood events in the Morgó-creek watershed. The goal is to find the main parameters that can represent the uncertainty of a flash-flood sensitive area, and how the calibrated and determined parameters take effect on a model if these values are shifted on given intervals.

Open Access: Yes

DOI: 10.1556/606.2022.00713

Impact of Different Rainfall Intensity and Duration on Flash-Flood Events on a Steep-Sloped Ungauged Watershed

Katalin Bene Gergely Ámon

Publication Name: Chemical Engineering Transactions

Publication Date: 2023-01-01

Volume: 107

Issue: Unknown

Page Range: 175-180

Description:

Changing climate conditions increase rainfall intensity and cause a growing number of flash flood events. Due to flash floods, problems with water damage prevention (urban area floods, erosion of natural watersheds) are increasing; these events also make the sustainable maintenance of watersheds more challenging. Hungarian watersheds are ungauged; very little historical or real-time data is available, making it difficult to understand the hydrological processes occurring during flash flood events. When only limited data is available, numerical models help predict peak flows and runoff volume. Additionally, a comparison of different models and parametrizations could be a helpful tool to reduce prediction uncertainty. This paper evaluates the impact of different rainfall intensities and durations on flash flood events at the ungauged watershed of the Morgó-creek on the northern side of Hungary. Land use conditions are primarily natural, with urban areas close to the outlet point. Hydrological and hydrodynamical models were used to apply different scenarios to determine the sensitivity of the whole watershed system based on typical precipitation events in time and intensity. The models predicted different peak flows and timing for flash floods. Using both models for comparison is recommended for flash flood prediction to compensate for the lack of measured data.

Open Access: Yes

DOI: 10.3303/CET23107030