Nibedita Guru

Bio: Nibedita Guru is an academic researcher from Forest Research Institute. The author has contributed to research in topics: Drainage basin & Flood myth. The author has an hindex of 4, co-authored 10 publications receiving 50 citations. Previous affiliations of Nibedita Guru include National Institute of Technology, Raipur & National Institute of Technology, Rourkela.

Flood Frequency Analysis of Partial Duration Series Using Soft Computing Techniques for Mahanadi River Basin in India

Abstract: In flood frequency analysis, the modeling based on Annual Maximum Flood (AMF) series remains the most popular approach. An alternative approach based on the “partial duration series (PDS) or peaks over threshold (POT)” has been considered in recent years, which captures more information about extreme events by fixing appropriate threshold values. The PDS approach has lot of advantages, (i) it consist more peak events by selecting the appropriate threshold hence to capture more information regarding the flood phenomena. (ii) it analyses both, the time of arrival and the magnitude of peaks, (iii) it provides extra flexibility in the demonstration of floods and a complete explanation of the flood generating process. However, the PDS approach remains underused and unpopular due to the nonexistence of general framework regarding different approaches.The first objective of the present research work is to develop a framework in the above question on selection of an appropriate threshold value using different concepts and, to verify the independency and stationarity criteria of the extreme events for the modeling of the PDS in the Mahanadi river system, India. For the analysis, daily discharge data from 22 stations with record length varying between 10 and 41 years have been used with the assumption that the whole basin is homogeneous in nature. The results confirmed that the Generalized Pareto (GP) best described the PDS in the study area and also, show that the best PDS/GP performance is found in almost all the value of λ (2, 2.5 and 3). In the second phase, the analysis is done to carry out the regional flood frequency analysis in the Mahanadi basin and to apply the developed model to the respective homogeneous region. Regionalization is the best viable way of improving flood quantile estimation. In the regional flood frequency analysis, selection of basin characteristics, morphology, land use and hydrology have significant role in finding the homogeneous regions. In this work the Mahanadi basin is divided into homogeneous regions by using fifteen effective variables initially. However, it has been observed that the whole basin is not hydro meteorologically homogeneous. Therefore, Factor analysis has been introduced in finding suitable number of variables, and nine variables are found suitable for analysis. Hierarchical (HC) and K-Means Clustering (KM) techniques are used for finding out the possible number of clusters. Here, again the Generalized Pareto (GP) distribution best described the PDS in the study area. To test the homogeneity and to identify the best-fit frequency distribution, regional L-moment algorithm is used. A unique regional flood frequency curve is developed which can estimate the flood quantiles in ungauged catchments and an index flood is also specified concerning the catchment characteristics by using the multiple linear regression approach.

Flood estimation in Mahanadi river system, India using partial duration series

Abstract: Flood frequency analysis is a pre-requisite for setting up and safeguarding of many hydraulic structures, such as dams, barrages, check-dams, culverts and urban drainage systems. In the flood frequency analysis, partial duration series (PDS) may be considered when dealing with values exceeding certain limits causing floods. In fact, the PDS is capable of getting more information about extreme events than the annual maximum series (AMS). Additionally, an assumption that, the magnitude of the extreme events of a PDS is best described by a generalized Pareto (GP) distribution. The present work investigates the at-site flood frequency analysis to find the average number of peaks (λ) for modelling the PDS on the basis of the PDS/GP assumption and variability in the GP parameters coupled with the quantile estimation with an increase in the value of average number of peaks (λ) each year in the Mahanadi river system, Odisha, India. Also, to verify the PDS/GP assumption we tested seven different frequency ...

Flood frequency analysis for Tel sub-basin of Mahanadi River, India using Weibull, Gringorten and L-moments formula

Abstract: The objective of this study is to determine the magnitude and frequency of floods for Tel sub-basin of Mahanadi river system, India using Gumbel distribution. The probability plot and flood-frequency curves by Gumbel distribution of each individual station are prepared using three different plotting position formulas (i.e. Weibull, Gringorten and L-moments). From the results and analysis of two stations of Tel sub-basin, Gumbel distribution based on L-moments always gives the least ratio of peak discharge of T years recurrence interval over mean annual flood (QT/MAF), also the pertinence of L-moments with Gumbel distribution have some limitations and it is only good for small samples data. If compared between Gumbel distribution by Weibull formula and Gumbel distribution by Gringorten formula, the latter is better because it gives the least ratio (which is in agreement with the literature). Therefore, it could be concluded that for both the stations Lmoments method is the best, but since L-moments method have some limitations, Gringorten formula is still the best plotting position method to be applied with Gumbel distribution. Keywords— Gringorten; Gumbel Distribution; L-moment; Weibull

Artificial neural networks

Abstract: Artificial neural networks (ANNs) constitute a class of flexible nonlinear models designed to mimic biological neural systems. In this entry, we introduce ANN using familiar econometric terminology and provide an overview of ANN modeling approach and its implementation methods. † Correspondence: Chung-Ming Kuan, Institute of Economics, Academia Sinica, 128 Academia Road, Sec. 2, Taipei 115, Taiwan; ckuan@econ.sinica.edu.tw. †† I would like to express my sincere gratitude to the editor, Professor Steven Durlauf, for his patience and constructive comments on early drafts of this entry. I also thank Shih-Hsun Hsu and Yu-Lieh Huang for very helpful suggestions. The remaining errors are all mine.

Different glacier status with atmospheric circulations in Tibetan Plateau and surroundings

Abstract: Glacial melting in the Tibetan Plateau affects the water resources of millions of people. This study finds that—partly owing to changes in atmospheric circulations and precipitation patterns—the most intensive glacier shrinkage is in the Himalayan region, whereas glacial retreat in the Pamir Plateau region is less apparent.