scholarly journals Return Level Analysis of the Hanumante River Using Structured Expert Judgment: A Reconstruction of Historical Water Levels

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3229
Author(s):  
Paulina E. Kindermann ◽  
Wietske S. Brouwer ◽  
Amber van Hamel ◽  
Mick van Haren ◽  
Rik P. Verboeket ◽  
...  
Keyword(s):  
Water Level ◽  
Historical Data ◽  
Classical Model ◽  
Expert Judgment ◽  
Water Levels ◽  
Return Level ◽  
Considerable Uncertainty ◽  
Level Data ◽  
Rain Events ◽  
Level Analysis

Like other cities in the Kathmandu Valley, Bhaktapur faces rapid urbanisation and population growth. Rivers are negatively impacted by uncontrolled settlements in flood-prone areas, lowering permeability, decreasing channels widths, and waste blockage. All these issues, along with more extreme rain events during the monsoon due to climate change, have led to increased flooding in Bhaktapur, especially by the Hanumante River. For a better understanding of flood risk, the first step is a return level analysis. For this, historical data are essential. Unfortunately, historical records of water levels are non-existent for the Hanumante River. We measured water levels and discharge on a regular basis starting from the 2019 monsoon (i.e., June). To reconstruct the missing historical data needed for a return level analysis, this research introduces the Classical Model for Structured Expert Judgment (SEJ). By employing SEJ, we were able to reconstruct historical water level data. Expert assessments were validated using the limited data available. Based on the reconstructed data, it was possible to estimate the return periods of extreme water levels of the Hanumante River by fitting a Generalized Extreme Value (GEV) distribution. Using this distribution, we estimated that a water level of about 3.5 m has a return period of ten years. This research showed that, despite considerable uncertainty in the results, the SEJ method has potential for return level analyses.

scholarly journals Water level oscillations in Monterey Bay and Harbor

Ocean Science ◽  
2015 ◽  
Vol 11 (3) ◽  
pp. 439-453 ◽  
Author(s):  
J. Park ◽  
W. V. Sweet ◽  
R. Heitsenrether
Keyword(s):  
Water Level ◽  
Wave Energy ◽  
Normal Modes ◽  
Low Frequency ◽  
Water Levels ◽  
Level Data ◽  
Modal Amplitude ◽  
Primary Driver ◽  
Potential Mode ◽  
Offshore Wave

Abstract. Seiches are normal modes of water bodies responding to geophysical forcings with potential to significantly impact ecology and maritime operations. Analysis of high-frequency (1 Hz) water level data in Monterey, California, identifies harbor modes between 10 and 120 s that are attributed to specific geographic features. It is found that modal amplitude modulation arises from cross-modal interaction and that offshore wave energy is a primary driver of these modes. Synchronous coupling between modes is observed to significantly impact dynamic water levels. At lower frequencies with periods between 15 and 60 min, modes are independent of offshore wave energy, yet are continuously present. This is unexpected since seiches normally dissipate after cessation of the driving force, indicating an unknown forcing. Spectral and kinematic estimates of these low-frequency oscillations support the idea that a persistent anticyclonic mesoscale gyre adjacent to the bay is a potential mode driver, while discounting other sources.

scholarly journals Transfer Entropy as a Tool for Hydrodynamic Model Validation

Entropy ◽  
2018 ◽  
Vol 20 (1) ◽  
pp. 58 ◽  
Author(s):  
Alicia Sendrowski ◽  
Kazi Sadid ◽  
Ehab Meselhe ◽  
Wayne Wagner ◽  
David Mohrig ◽  
...  
Keyword(s):  
Water Level ◽  
Numerical Models ◽  
Water Levels ◽  
Transfer Entropy ◽  
Spatial And Temporal Scales ◽  
River Deltas ◽  
Level Data ◽  
Water Level Data ◽  
Wax Lake Delta ◽  
Validation Tool

The validation of numerical models is an important component of modeling to ensure reliability of model outputs under prescribed conditions. In river deltas, robust validation of models is paramount given that models are used to forecast land change and to track water, solid, and solute transport through the deltaic network. We propose using transfer entropy (TE) to validate model results. TE quantifies the information transferred between variables in terms of strength, timescale, and direction. Using water level data collected in the distributary channels and inter-channel islands of Wax Lake Delta, Louisiana, USA, along with modeled water level data generated for the same locations using Delft3D, we assess how well couplings between external drivers (river discharge, tides, wind) and modeled water levels reproduce the observed data couplings. We perform this operation through time using ten-day windows. Modeled and observed couplings compare well; their differences reflect the spatial parameterization of wind and roughness in the model, which prevents the model from capturing high frequency fluctuations of water level. The model captures couplings better in channels than on islands, suggesting that mechanisms of channel-island connectivity are not fully represented in the model. Overall, TE serves as an additional validation tool to quantify the couplings of the system of interest at multiple spatial and temporal scales.

scholarly journals Multi-objective optimization of typhoon inundation forecast models for water-level gauging network by integration of ARMAX with a Genetic Algorithm

2016 ◽  
Author(s):  
Huei-Tau Ouyang
Keyword(s):  
Genetic Algorithm ◽  
Water Level ◽  
Water Levels ◽  
Time Shift ◽  
Multi Objective ◽  
Cumulative Rainfall ◽  
Level Data ◽  
Water Level Data ◽  
Forecast Models ◽  
Gauging Station

Abstract. The forecasting of inundation levels during typhoons requires that multiple objectives be taken into account, including the forecasting capacity with regard to variations in water level throughout the entire weather event, the accuracy that can be attained in forecasting peak water levels and the time at which peak water levels are likely to occur. This paper proposed a means of forecasting inundation levels in real-time using monitoring data from a water-level gauging network. ARMAX was used to construct water-level forecast models for each gauging station using input variables including cumulative rainfall and water level data from other gauging stations in the network. Analysis of the correlation between cumulative rainfall and water level data makes it possible to obtain an approximation as to the cumulative duration of rainfall and time lags associated with each gauging station. Analyses on water levels as well as on cumulative rainfall enable the identification of associate sites pertained to each gauging station that share high correlations with regard to water level and low mutual information with regard to cumulative rainfall. Water level data from associate sites is used as a second input variable for the water-level forecast model of the target site. Three indices were considered in the selection of an optimal model: the coefficient of efficiency (CE), error in the stage of peak water level (ESP), and relative time shift (RTS). We used a multi-objective genetic algorithm to derive an optimal Pareto set of models capable of performing well in the three objectives. A case study was conducted on the Xinnan area of Yilan County, Taiwan in which optimal water-level forecast models were established for each of the four water-level gauging stations in the area. Test results demonstrate that the model best able to satisfy PE exhibited significant time shift, whereas the models best able to satisfy CE and RTS provide accurate forecasts of inundations when variations in water level are less extreme.

scholarly journals Vision-based system for the control and measurement of wastewater flow rate in sewer systems

2009 ◽  
Vol 60 (9) ◽  
pp. 2281-2289 ◽  
Author(s):  
L. S. Nguyen ◽  
B. Schaeli ◽  
D. Sage ◽  
S. Kayal ◽  
D. Jeanbourquin ◽  
...  
Keyword(s):  
Image Processing ◽  
Water Level ◽  
Water Levels ◽  
Combined Sewer Overflows ◽  
Web Based ◽  
Tier System ◽  
Crucial Information ◽  
Rain Events ◽  
Processing Techniques

Combined sewer overflows and stormwater discharges represent an important source of contamination to the environment. However, the harsh environment inside sewers and particular hydraulic conditions during rain events reduce the reliability of traditional flow measurement probes. In the following, we present and evaluate an in situ system for the monitoring of water flow in sewers based on video images. This paper focuses on the measurement of the water level based on image-processing techniques. The developed image-based water level algorithms identify the wall/water interface from sewer images and measure its position with respect to real world coordinates. A web-based user interface and a 3-tier system architecture enable the remote configuration of the cameras and the image-processing algorithms. Images acquired and processed by our system were found to reliably measure water levels and thereby to provide crucial information leading to better understand particular hydraulic behaviors. In terms of robustness and accuracy, the water level algorithm provided equal or better results compared to traditional water level probes in three different in situ configurations.

scholarly journals Deteksi Level Ketinggian Air Dengan Nikelin, Encoder dan Sensor Tekanan Untuk Sistem Peringatan Dini Banjir

2021 ◽  
Vol 1 ◽  
pp. 45-49
Author(s):  
Latiful Hayat ◽  
Dian Nova Kusuma Hardani
Keyword(s):  
Water Level ◽  
Early Warning ◽  
Pressure Sensor ◽  
Pressure Sensors ◽  
Warning System ◽  
Water Levels ◽  
Nickel Wire ◽  
High Data ◽  
Level Data ◽  
Water Level Data

Floods and their problems show an increasing indication when rainfall is high. Data from BNPB shows that floods, landslides and tornadoes contributed to the total disasters in Indonesia in a decade. The existence of an early warning flood disaster can help evacuate before a disaster strikes. The system requires a water level detector as the basic data for determining flood predictions. In order to get the water level value, a touch water method can be used using electrodes or without touching the water with the help of pressure sensors, ultrasonic and imaging. Each method has advantages over the other. In this study, the effectivity and accuracy of detecting water levels were investigated using 3 methods: the direct touch of water through nickel wire, buoys with encoder, and pressure sensors. Detection of water levels can be used as a reference to obtain river water level data which is then connected via an IoT or internet connection as a reference for the Early Warning System for the arrival of floods. This study found that changes in water level of less than 30 cm can utilize buoys and encoders with an accuracy of detecting 5 to 6 counts per 1 mm increase in water level. Meanwhile, the measurement of less than 30 cm water level using nickel wire resulted in a non-linear value. The utilization of nickel wire can be used for a height of more than 30 cm where the change in resistivity has started to be linear. ADC change value is 2.93 mV/cm using 10 bit ADC at 5 Volt reference voltage. For water level heights of 50 cm and above, a pressure sensor can use a pressure sensor that can detect changes in pressure of 0.002 in Hg/mm or 0.05 mmHg/mm.

scholarly journals Assimilating SAR-derived water level data into a hydraulic model: a case study

2011 ◽  
Vol 8 (1) ◽  
pp. 2103-2144 ◽  
Author(s):  
L. Giustarini ◽  
P. Matgen ◽  
R. Hostache ◽  
M. Montanari ◽  
D. Plaza ◽  
...  
Keyword(s):  
Particle Filter ◽  
Water Level ◽  
Cross Sections ◽  
Hydraulic Model ◽  
Water Levels ◽  
Hydraulic Models ◽  
Level Data ◽  
Water Level Data ◽  
Assimilation Scheme

Abstract. Satellite-based active microwave sensors not only provide synoptic overviews of flooded areas, but also offer an effective way to estimate spatially distributed river water levels. If rapidly produced and processed, these data can be used for updating hydraulic models in near real-time. The usefulness of such approaches with real event data sets provided by currently existing sensors has yet to be demonstrated. In this case study, a Particle Filter-based assimilation scheme is used to integrate ERS-2 SAR and ENVISAT ASAR-derived water level data into a one-dimensional (1-D) hydraulic model of the Alzette River. Two variants of the Particle Filter assimilation scheme are proposed with a global and local particle weighting procedure. The first option finds the best water stage line across all cross sections, while the second option finds the best solution at individual cross sections. The variant that is to be preferred depends on the level of confidence that is attributed to the observations or to the model. The results show that the Particle Filter-based assimilation of remote sensing-derived water elevation data provides a significant reduction to the model forecast uncertainty. Moreover, it is shown that the periodical updating of hydraulic models through the proposed assimilation scheme leads to an improvement of model predictions over several time steps. However, the performance of the assimilation depends on the skill of the hydraulic model and the quality of the observation data.

Water level changes in Swedish lake systems using pixel-specific Sentinel-1 phase change

2021 ◽  
Author(s):  
Saeid Aminjafari ◽  
Fernando Jaramillo
Keyword(s):  
Phase Change ◽  
Water Level ◽  
Open Water ◽  
Water Levels ◽  
Large Lakes ◽  
Radar Altimetry ◽  
Water Level Changes ◽  
Level Data ◽  
Wide Range ◽  
Image Pairs

<p>Sweden has approximately 100,000 lakes covering roughly nine percent of the country’s surface area. These lakes are one of the important sources of fresh water for urban, industrial, and agricultural use, further providing a wide range of ecosystem services. In order to conserve and protect the lakes from the impacts of climate change, hydrologic monitoring should ideally be conducted in all of these lakes. However, it is almost impossible to gauge all of these lakes on a regular basis, due to economical and logistic constraints. Radar altimetry has been successfully used to obtain water levels from specific lakes; however, the technology can only be used in large lakes that are located precisely under the orbit of the satellite, thus excluding most Swedish lakes. We here develop a new procedure based on the application of differential interferometric synthetic aperture radar (DInSAR) on sequential image pairs with short temporal baseline to measure the water level of 36 lakes. We processed Sentinel-1 twin satellite data with 6-day revisiting intervals, pair by pair, from March 2019 to November 2019. In total, we constructed 41 interferograms considering only the pixels with coherence values greater than 0.2 in all interferograms to ensure consistent scattering and good coherence in all images. We found that the pixels located near tree trunks in flat areas or near steep cliffs in mountainous areas showed a steady phase change in all interferograms that could be converted to water level change. In some of these lakes, the water level changes derived from this methodology correlated well with the in-situ water level of the gauge stations provided by the Swedish Meteorological and Hydrological Institute. We believe that this methodology has good potential for monitoring water level data in small lakes that cannot be monitored by radar altimetry, and serves as evidence of the unknown potential of DInSAR to track hydrological changes in open water surfaces.</p>

scholarly journals Particle Tracking Using Dynamic Water-Level Data

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 2063
Author(s):  
Yuan Gao
Keyword(s):  
Groundwater Flow ◽  
Water Level ◽  
Water Table ◽  
Flow Direction ◽  
Water Levels ◽  
Subsurface Water ◽  
Pressure Transducers ◽  
Level Data ◽  
Water Level Data ◽  
Fluid Particles

The movement of fluid particles about historic subsurface releases is often governed by dynamic subsurface water levels. Motivations for tracking the movement of fluid particles include tracking the fate of subsurface contaminants and resolving the fate of water stored in subsurface aquifers. This study provides a novel method for predicting the movement of subsurface particles relying on dynamic water-level data derived from continuously recording pressure transducers. At least three wells are needed to measure water levels which are used to determine the plain of the water table. Based on Darcy’s law, particle flow pathlines at the study site are obtained using the slope of the water table. The results show that hydrologic conditions, e.g., seasonal transpiration and precipitation, influence local groundwater flow. The changes of water level in short periods caused by the hydrologic variations made the hydraulic gradient diversify considerably, thus altering the direction of groundwater flow. Although a range of groundwater flow direction and gradient with time can be observed by an initial review of water levels in rose charts, the net groundwater flow at all field sites is largely constant in one direction which is driven by the gradients with higher magnitude.

scholarly journals Multi-objective optimization of typhoon inundation forecast models with cross-site structures for a water-level gauging network by integrating ARMAX with a genetic algorithm

2016 ◽  
Vol 16 (8) ◽  
pp. 1897-1909 ◽  
Author(s):  
Huei-Tau Ouyang
Keyword(s):  
Genetic Algorithm ◽  
Water Level ◽  
Water Levels ◽  
Time Shift ◽  
Cumulative Rainfall ◽  
Level Data ◽  
Water Level Data ◽  
Forecast Models ◽  
Gauging Station ◽  
Cross Site

Abstract. The forecasting of inundation levels during typhoons requires that multiple objectives be taken into account, including the forecasting capacity with regard to variations in water level throughout the entire weather event, the accuracy that can be attained in forecasting peak water levels, and the time at which peak water levels are likely to occur. This paper proposed a means of forecasting inundation levels in real time using monitoring data from a water-level gauging network. ARMAX was used to construct water-level forecast models for each gauging station using input variables including cumulative rainfall and water-level data from other gauging stations in the network. Analysis of the correlation between cumulative rainfall and water-level data makes it possible to obtain the appropriate accumulation duration of rainfall and the time lags associated with each gauging station. Analyses on cross-site water levels as well as on cumulative rainfall enable the identification of associate sites pertaining to each gauging station that share high correlations with regard to water level and low mutual information with regard to cumulative rainfall. Water-level data from the identified associate sites are used as a second input variable for the water-level forecast model of the target site. Three indices were considered in the selection of an optimal model: the coefficient of efficiency (CE), error in the stage of peak water level (ESP), and relative time shift (RTS). A multi-objective genetic algorithm was employed to derive an optimal Pareto set of models capable of performing well in the three objectives. A case study was conducted on the Xinnan area of Yilan County, Taiwan, in which optimal water-level forecast models were established for each of the four water-level gauging stations in the area. Test results demonstrate that the model best able to satisfy ESP exhibited significant time shift, whereas the models best able to satisfy CE and RTS provide accurate forecasts of inundations when variations in water level are less extreme.

scholarly journals Water level oscillations in Monterey Bay and Harbor

2014 ◽  
Vol 11 (6) ◽  
pp. 2569-2606
Author(s):  
J. Park ◽  
W. Sweet ◽  
R. Heitsenrether
Keyword(s):  
Water Level ◽  
Wave Energy ◽  
Normal Modes ◽  
Low Frequency ◽  
Water Levels ◽  
Level Data ◽  
Modal Amplitude ◽  
Primary Driver ◽  
Potential Mode ◽  
Offshore Wave

Abstract. Seiches are normal modes of water bodies responding to geophysical forcings with potential to significantly impact ecology and maritime operations. Analysis of high-frequency (1 Hz) water level data in Monterey California identifies Harbor modes between 10 and 120 s that are attributed with specific geographic features. It found that modal amplitude modulation arises from cross-modal interaction and that offshore wave energy is a primary driver of these modes. Synchronous coupling between modes is observed to significantly impact dynamic water levels. At lower frequencies between 15 and 60 min modes are independent of offshore wave energy, yet are continuously present. This is unexpected since seiches normally dissipate after cessation of the driving force, indicating an unknown forcing. Spectral and kinematic estimates of these low frequency oscillations supports the idea that a persistent anticyclonic mesoscale gyre adjacent to the Bay is a potential mode driver, while discounting other sources.

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