DESIGN OF STILLING BASIN FOR DECREASING BACK WATER IN THE DAM FOOT

Abstract

This research studies the hydraulic behavior and the problem solving alternatives of original
until final design, and the most effective stilling basin and downstream regulator channel for decreasing back
water from the upstream water level in the dam foot. The methodology consists of physical modeling in the
Laboratory of River and Swamp, Department of Water Resources, Faculty of Engineering, University of
Brawijaya. The methods include the USBR for the hydraulic analysis, the Hind’s formulation for the side
channel analysis, the energy equation by analyzing the standard step for the transition and the chute way
analysis, and the USBR type III for designing the stilling basin. A square cross-section with the Manning
coefficient of 0.40 is used for determining the control of the Tail Water Level (TWL) and a trapezoidal crosssection with the Manning coefficient of 0.39 is used for the final design. However, the equation of Schotlisch
and Veronise is used for the local scouring analysis. The result of Model Test and analysis indicates that
there are some differences among the analysis in every point of the building. Therefore, the relative error is
needed to know how big the error in the comparison result.This research studies the hydraulic behavior and the problem solving alternatives of original
until final design, and the most effective stilling basin and downstream regulator channel for decreasing back
water from the upstream water level in the dam foot. The methodology consists of physical modeling in the
Laboratory of River and Swamp, Department of Water Resources, Faculty of Engineering, University of
Brawijaya. The methods include the USBR for the hydraulic analysis, the Hind’s formulation for the side
channel analysis, the energy equation by analyzing the standard step for the transition and the chute way
analysis, and the USBR type III for designing the stilling basin. A square cross-section with the Manning
coefficient of 0.40 is used for determining the control of the Tail Water Level (TWL) and a trapezoidal crosssection with the Manning coefficient of 0.39 is used for the final design. However, the equation of Schotlisch
and Veronise is used for the local scouring analysis. The result of Model Test and analysis indicates that
there are some differences among the analysis in every point of the building. Therefore, the relative error is
needed to know how big the error in the comparison result.