Numerical Investigation on Effects of a Diversion Channel along a Meandering River Based on a 2D Model

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Study on Impact Force of Debris Flow due to Variable of Check Dam Shape

Impact often causes structural destruction and is the key element in engineering design and risk assessment. Nature of the debris flow characteristics are the front part of the flow, where big boulders accumulate, lasts only a few seconds and the following part that lasts long looks like a mud flow with gradually decreasing discharge. Besides, boulder impact force is much greater than fluid dynamic pressure. Therefore, it is necessary to make sure that the structure is affordable of boulder impact force. In this study, an attempt has been made to clarify the impact of grain size distribution on check dam and variable of check dam type with experimental methods

Debris-Flow Deposition and Erosion Processes of the Sediment Deposit Upstream of a Check Dam

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Investigation of Suspended Sediment Transport and Bed Deposition around Bandal-like Structures

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

Transient Slope Stability Analysis of Landslide Dam Failure

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Temporary De-Poldering for a Long Term Flood/Sediment Management in the Southwestern Bangladesh

Southwestern Bangladesh has been seriously affected by perennial waterlogging over the last few decades. It is primarily due to excessive riverbed siltation outside the polders after the construction of embankments along both sides of the tidal rivers. These embankments de-linked the huge natural floodplains and restricted a gradual process of natural deposition inside the polders. An introduction of the tidal basin concept by temporary de-poldering (embankment cut) at some designated locations has substantially solved the issues. The current chapter looks at the historical practice of flood/sediment management, the evolution of embankments and their de-poldering, inclusion of Tidal River Management (TRM) in long term flood/sediment management, and discusses a technical aspect of flood/sediment dynamics across the tidal river system. The process of restoring beneficial tidal flooding by cutting embankment at certain locations, commonly known as TRM, is not a novel method. The TRM has started from age-old practice and proves technically one of the effective methods of sustainable flood/sediment management in the tide-dominated river system. It is an example of building with nature, where little human interventions are needed, and a resilient measure for waterlogging, drainage-congestion, and river-siltation

Probabilistic Prediction Method of Erosion Volume and Deposition Area from Rainfall Observation Data

We propose a methodology to estimate the spatial distribution of the probability of sediment deposition due to debris flow from rainfall data by combining the probability prediction of erosion volume based on an ordinal logistic regression and a sediment transport simulation. By using the Receiver Operating Characteristic (ROC) curve and Area Under Curve (AUC) we have selected the best combination of shortand long-term rainfall indices used as explanatory variables in the ordinal logistic model. The results showed that the regression model using 60-minute and 48-hour rainfall indices performed well and that the regression model using three events improved the predictability of local disasters in 2014. Furthermore, we performed Monte Carlo debris-flow simulations using rainfall data from 2014 using the model. We confirmed that the spatial distribution of disaster probability is consistent with the actual damage

Appraising the Potential of Using Satellite‐Based Rainfall Estimates for Evaluating Extreme Precipitation: A Case Study of August 2014 Event Across the West Rapti River Basin, Nepal

Heavy precipitation events are recurrently occurring in Nepal, affecting lives and properties every year, especially in the summer monsoon season (i.e., June-September). We investigated an extreme (heavy) precipitation event of August 2014 over the West Rapti River (WRR) Basin, Nepal. First, we forced a rainfall-runoff model with ground-based (gauge) hourly rainfall data of nine stations. Second, we validated against hourly water level at an outlet of the WRR Basin. This study then evaluated the performance of different satellite-based rainfall estimates (SREs) in capturing an extreme precipitation event. We considered the use of half-hourly data of Integrated Multi-satellite Retrievals for GPM (IMERG) (Early, Late, and Final versions), spatial resolution (10 km), and hourly data of Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN), spatial resolution (25 km), and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Cloud Classification System (PERSIANN-CCS), spatial resolution (4 km). Also, we used 3 h data of Tropical Multi-satellite Precipitation Analysis (TMPA) product real-time (3B42RT), spatial resolution (25 km). In general, we find that all selected SREs depicted a similar pattern of extreme precipitation as shown by the gauge data on a daily scale. However, we find these products could not replicate precisely on a sub-daily scale. Overall, IMERG and TMPA showed a better performance than PERSIANN and PERSIANN-CCS. Finally, we corrected poor-performed SREs with respect to gauge data and also filled data gaps of gauge rainfall using the information of good-performed SREs. Our study reveals that there is a great challenge in local flood simulation employing SREs at high-temporal resolution in Nepal