Design of a road side drainage system along Katwe-Bwera road.

Abstract

The purpose of this project is to design an efficient, economic easy to maintain drainage system for the Katwe-Bwera road located in Katwe-kabatooro' T'C, Kasese district in south-western Uganda.The catchment area characteristics and land use maps were developed by use of Arch map 10.l and QGIS soft wares showing the contours, Slope, geology, soil type, land cover and watershed. The Rational Method was used to determine the discharge. First the IDF curves were developed from the 12-year rainfall data. From Kasese metrological center for a return period of 10 year using the Watkins and Fiddle’s method. Catchment areas, existing slopes of the roads and time of concentrations were calculated and computed by picking GPS points around the roads thus for points observed to pour their runoff towards the road in consideration which were integrated into a program called autoCADcivi3D which helped us estimate the area existing slopes and the time of concentrations. The concentration-time was then got from Kiprich's equation for sub catchments which was 5 minutes (min standard time of concentration as per Uganda road design manual) and. It was used to get the critical rainfall intensity of 85mm/hr from the IDP curves. The catchment area developed in AutoCAD was divided into four sub catchments Ai=77417m2 andA2=48971m 2, A3=42,500 and A4=077Zm2 The discharge was calculated Q1= 0.547m3/s, Q1=O.806m3 /s, Q3=1.136m3 /s and Q4=1;5-12m3/s then used to determine the drainage channels-with sideslopes or IH:3V and the depth varying between 130mm and 456mm with varying base between 1450mm and 450mm. Two culverts sizes were chosen to cater for the different discharges of diameter 900mm and 600mm.The entire project was estimated to cost 494,312,500 ug.shs