The Effect of Discharge Amount on Drainage Structure Failure A case Study on Ambo Town

Abstract

Drainage is one of the most important factors to be considered in the world to road design, construction and maintenance projects. Commonly, Inadequate drainage structure problems become one of the most common sources of problems from the residents and runoff water, flooding problems and this problem becoming worse in every year in Ethiopia. Poor existing drains and their improper operation of drainage mainly cause damage and problems to the road users and vehicles. Due to the development of infrastructures in the town, the surface runoff water greatly increased in Ambo town thus, damaging the drainage structure and road surface. The main objective of this research is, to investigate the major cause of the failure of drainage structures and to estimate the quantity of runoff for existing drainage structures. In order to attain the objective of the study, the researcher focused to collect Structural plan map of Ambo town, existing drainage structure plan, and rainfall data from Ambo town municipal office and Ethiopian metrological agency and also the dimensions of the side drainages were measured by the researcher on the field by using tap meter. The methods of data to be processed was by QSWAT for peak flow (Qp)to compare with the capacity of existing drainage structures of the areas if Qc>Qp is safe and Leveling instruments was determine the design slope and measured slope of the existing drainage structure at the area of case study. According to the out puts of slope from the leveling instrument of surveying data’s, the slopes of existing drainage and asphalt cross fall was a problem to drain the water from the road and drainage structures properly. And peak flows from QSWAT was determined the capacity of the existing drainage structure of trapezoidal and rectangular shapes. From these existing drainage types of study area, the rectangular type was drain safely from the structure than trapezoidal shape. The concerned authorities are strongly recommended to control and monitor the structural failure of drainage and Environmental problems by maintain and re-constructing the failure parts, developing the skill of QSWAT and QGIS software and by providing a specific budget annually to increase the service life and was the major recommended counter-measure