Mohammad Muzzammil

A reliability-based assessment of bridge pier scour in non-uniform sediments

The available scour equations for bridge pier are mostly deterministic in nature, which do not consider uncertainties of various scouring parameters adequately. A reliability-based assessment of bridge pier scour depth is of paramount importance in examining the relationship between safety factor and reliability, which are considered to be key parameters for decision-making in bridge foundation design. A methodology for the reliability assessment of bridge pier scour in non-uniform sediments are presented using the First Order Reliability Method (FORM). To study the influence of various random variables on the pier reliability against the scouring, a sensitivity analysis was carried out. To achieve a desirable safety level in the design of pier foundation, reliability-based safety factors are also proposed. The influence of the correlation among the random variables on the pier reliability was also assessed.

A Spreadsheet Approach for Prediction of Rating Curve Parameters

Streamflow data is required for planning and design of various hydraulic structures and water resource projects such as bridges, culverts, flood plain zoning, flood protection works, flood warning systems, and assessment of water resources potential. A reliable and continuous record of streamflow data is, therefore, of utmost importance. However, it is very difficult to maintain a continuous record of discharge and sometimes even impractical during floods. A continuous record of elevation of water surface in a stream above some arbitrary datum or the stage of river is rather easy and accurate as compared to discharge. A functional relationship between stage and discharge at a site in a river is called the rating curve. The accuracy of discharge estimated from the rating curve depends on the accuracy of stage measurement and development of the rating curve. The conventional method of regression analysis for the development of the rating curve often fails to give stage–discharge relationship accurately. In the present study, a simple and quick Excel solver technique has been used for the development of the rating curve accurately. The results of the solver in Excel are compared with conventional method of regression analysis. The statistical parameters such as root mean square error, correlation coefficient, and Nash criteria were computed for assessment of the performance of these methods for the rating curve development. It has been found that the performance of the Excel solver is better than that of the conventional method.

EXTRAPOLATION ERROR IN PEAK FLOODS FOR THE RIVERS GANGA AND YAMUNA

ABSTRACT A reliable estimate of probable peak flood is not only essential for the safety of any hydraulic structure but also for the safety of lives and properties that are likely to-be affected by floods. The frequency analysis of annual peak flood is generally considered to be the best among the existing methods for flooding estimation if sufficient historical flood data are available. If the flood data are of shorter period, it is necessary to extrapolate the peak floods for required length of period which results in extrapolation error. Some of the references on the study of error caused by extrapolation are available. However, all the past investigators assumed a particular frequency distribution, which may not be representative for the flood data and hence the error due to assumed distribution of frequency might have crept in their analysis. The present study has been carried out to investigate the extrapolation error for the two major North Indian rivers Ganga and Yamuna after selecting the best fi...