Wyniki wyszukiwania - BazTech

1

Evaluating lateral riverbank erosion with sediment yield through integrated model in lower Gangetic floodplain, India

Ghosh Arnab, Roy Malabika Biswas, Roy Pankaj Kumar

Acta Geophysica

|

2022

|

Vol. 70, no 4

1769--1795

EN

One of the natural disasters caused by river meandering is riverbank erosion, which creates social, economic, and environmental problems in the riparian zone and serves as a source of increasing sedimentation levels in the river. Riverbank erosion and bank failure create a complex cyclical process, such as riverbank retreat, which cannot be easily measured and predicted by any model. The meandering flow along the Bhagirathi-Hooghly river has created riverbank erosion and riverbank retreat conditions in several areas, through which measuring bank stability and erosion is quite complex. As a result, the BSTEM model, integrating with HEC-RAS, has been used in this article to measure riverbank erosion and retreat accurately. Riverbank erosion and retreat data for 2019–2020 have been simulated based on data observed from 2016 to 2018 for accurate measurement. In addition, the total sediment yielded from the river bank has been calibrated and simulated with the help of sediment transport formulation in HEC-RAS, which indicates a gradual increase in river erosion at present (2019–2020). This model is expected to help formulate government policy on protecting riverbank erosion and river restoration in the future.

2

Comparative study for deriving stagedischarge - sediment concentration relationships using soft computing techniques

Sihag P., Sadikhani M. R., Vambol V., Vambol S., Prabhakar A. K., Sharma N.

Journal of Achievements in Materials and Manufacturing Engineering

|

2021

|

Vol. 104, nr 2

57--76

EN

Purpose: Knowledge of sediment load carried by any river is essential for designing and planning of hydro power and irrigation projects. So the aim of this study is to develop and evaluating the best soft-computing-based model with M5P and Random Forest regressionbased techniques for computation of sediment using datasets of daily discharge, daily gauge and sediment load at the Champua gauging site of the Upper Baitarani river basin of India. Design/methodology/approach: Last few decades, the soft computing techniques based models have been successfully used in water resources modelling and estimation. In this study, the potential of tree based models are examined by developing and comparing sediment load prediction models, based on M5P tree and Random forest regression (RF). Several M5P and RF based models have been applied to a gauging site of the Baitarani River at Odisha, India. To evaluate the performance of the selected M5P and RF-based models, three most popular statistical parameters are selected such as coefficient of correlation, root mean square error and mean absolute error. Findings: A comparison of the results suggested that RF-based model could be applied successfully for the prediction of sediment load concentration with a relatively higher magnitude of prediction accuracy. In RF-based models Qt, Q(t-1), Q(t-2), S(t-1), S(t-2), Ht and H(t-1) combination based M10 model work superior than other combination based models. Another major outcome of this investigation is Qt, Q(t-1) and S(t-1) based model M4 works better than other input combination based models using M5P technique. The optimum input combination is Qt, Q(t-1) and S(t-1) for the prediction of sediment load concentration of the Baitarani River at Odisha, India. Research limitations/implications: The developed models were tested for Baitarani River at Odisha, India.

3

Dynamics of suspended sediment load with respect to summer discharge and temperatures in Shaune Garang glacierized catchment, Western Himalaya

Kumar R., Kumar R., Singh S., Singh A., Bhardwaj A., Kumari A., Randhawa S. S., Saha A.

Acta Geophysica

|

2018

|

Vol. 66, no. 5

1109--1120

EN

The observed and predicted rise in temperature will have deleterious impact on melting of snow and ice and form of precipitation which is already evident in Indian Himalayan Region. The temperature-dependent entities like discharge and sediment load will also vary with the observed and predicted rise posing environmental, social and economic threat in the region. There is little known about sediment load transport in relation to temperature and discharge in glacierized catchments in Himalaya mainly due to the scarcity of ground-based observation. The present study is an attempt to understand the suspended sediment load and transportation in relation to variation in discharge and temperature in the Shaune Garang catchment. The result shows strong dependence of sediment concentration primarily on discharge (R2 = 0.84) and then on temperature (R2 = 0.79). The catchments with similar geological and climate setting were observed to have comparatively close weathering rate. The sediment load was found to be higher in the catchments in eastern and central part of Indian Himalayan Region in comparison with western part due to dominance of Indian Summer Monsoon leading to high discharge. The annual physical weathering rate in Shaune Garang catchment was found to be 411 t km−2 year−1 which has increased from 327 t km−2 year−1 in around three decades due to rise in temperature causing increase in discharge and proportion of debris-covered glacierized area.

4

Developing nonlinear models for sediment load estimation in an irrigation canal

Ahmed F., Hassan M., Hashmi H. N.

Acta Geophysica

|

2018

|

Vol. 66, no. 6

1485--1494

EN

The study was performed to estimate the weekly sediment load in Thal canal located in Mianwali district Punjab, Pakistan. Past records of sediments and discharge have been considered as the input parameters. The best input combinations have been identified with the help of advanced algorithms including full, sequential and increasing embedding, genetic algorithm and hill climbing in combination with the gamma test. Model training has been carried out using two artificial neural networkbased algorithms, namely Broyden–Fletcher–Goldfarb–Shanno (BFGS), back-propagation and a local linear regression technique. A variety of statistical parameters including R square, root mean squared error, mean square error and mean bias error (MBE) has been calculated in order to evaluate the best models. The results strongly suggested that BFGS-based model performed better than all other models with remarkably low values of MBE. Significantly high values of correlation coefficient (R square) in both training and testing evidenced a close similarity between actual and predicted sediment load values for the same model.

5

Impact of urbanization on the sediment yield in tropical watershed using temporal land-use changes and a GIS-based model

Bello A.-A. D., Hashim N. B., Haniffah R. M.

Journal of Water and Land Development

|

2017

|

no. 34

33--45

EN

Abundant rainfall areas promote sediment yield at both sub-watershed and watershed scale due to soil erosion and increase siltation of river channel, but it can be curtailed through planned urbanization. The urbanization of Skudai watershed is analysed from historical and future perspective. A GIS-based model (Hydrological Simulation Programme-FORTRAN-HSPF) is used to modelled sediment flow using basin-wide simulation, and the output result is utilized in evaluating sediment yield reduction due to increased urbanization by swapping multiple temporal land-use of decadent time-steps. The analysis indicates that sediment yield reduces with increase urban built-up and decrease forest and agricultural land. An estimated 12 400 tons of sediment will be reduced for every 27% increase in built-up areas under high rainfall condition and 1 490 tons at low rainfall. The sensitivity analysis of land-use classes shows that built-up, forest and barren are more sensitive to sediment yield reduction compared to wetland and agricultural land at both high and low rainfall. The result of the study suggests that increased urbanization reduced sediment yield in proportion to the rainfall condition and can be used as an alternative approach for soil conservation at watershed scale independent of climate condition.

PL

Duże opady atmosferyczne sprzyjają przemieszczaniu się osadów w skali zlewni w wyniku erozji gleby, powodując zamulanie koryta rzecznego. Procesy te można ograniczyć przez planową urbanizację. Urbanizację zlewni Skudai analizowano w perspektywie historycznej (przedziały 10-letnie) i w kontekście przyszłych zmian. Do modelowania przepływu osadu użyto programu symulacji hydrologicznej Fortran (HSPF), a wyniki modelowania wykorzystano do oceny zmniejszenia ilości osadu związanej z urbanizacją. Analiza wskazuje, że ładunek osadów maleje ze zwiększeniem udziału zabudowy miejskiej oraz z ograniczeniem powierzchni lasów i gruntów rolniczych. W warunkach intensywnych opadów ładunek osadu może zmaleć o 12 400 t, gdy udział terenów zabudowanych zwiększy się o 27%. W warunkach małych opadów ładunek zmniejszy się o 1 490 t. Analiza wrażliwości klas użytkowania ziemi wykazała, że obszary zabudowane, lasy i ugory są bardziej wrażliwe na zmniejszenie ładunku osadu niż obszary podmokłe i grunty rolnicze, zarówno w warunkach dużego jak i małego natężenia opadów. Wyniki badań sugerują, że zwiększony udział terenów zabudowanych ogranicza ładunek osadów proporcjonalnie do ilości opadów, w związku z czym planowa urbanizacja może być wykorzystana jako alternatywne podejście do ochrony gleb w skali zlewni, niezależnie od warunków klimatycznych.