Proper and sufficient urban drainage structure is very essential in one city like Woldiya town in order to protect road infrastructure, public and private properties and even societies life’s. Woldiya town existing drainage structures have many problems in summer season due to inadequate size and accumulation of solid wastes in different parts of the town. As a result during summer season peoples are suffering to do their day to day life and damaging road infrastructure. The objective of this study is to assess the performance of existing drainage structure and to propose best management practices in order to withstand the flood generated from the catchment. Spatial data such as location and boundary of catchments and temporal data like returning period and land use patterns were used to analysis the hydrology like rain fall and hydraulic such as width and depth of the existing drainage system. To estimate design rainfall for different return period the frequency analysis method is used to determine the exceedance probability of the rain intensity for each duration. L- moment method were used to select the best fit probability distribution function from normal distribution, long normal distribution, Gumble distribution, General Extreme value distribution , log person type III and general parento distribution .Modified rational equation and SCS CN methods are used to estimate the peak flood generated from the catchment. Existing cross sectional size of the drainage structures is measured directly from the field. The flood profile of all drainage line was analysis by Bentley civil storm. The challenges of existing drainage system were investigated by field survey and by interviewing local community. The best management practice was designed by using of hydraulic tool box . From L moment result, Log person type III distributions are the best fit distribution with skewness value = 0.64 and kurtosis value = 0.41. The results from model compared with existing hydraulic capacity of the channels and it shows that at Tnfaze to shall, Medhanialem church to Adago circle,Teklehaymanot cherch to Gubalafto sefer and Gubalafto to Adago storm water drainage were not sufficient to carry the expected runoff during rainfall events. In this study, the alternative hypothesis 3 is accepted which means both hydraulic and accommodation of solid waste and sediments accumulation have influence for Woldiya town drainage problem. In the upstream side of the town has much amount of flood generated to the city. Hence, additional drainage structure at the upstream side of the city is proposed to intercept the flood generated from the upstream of the town and to manage the excess storm water flowing over the road surface. Key words: Woldiya town, storm water, L moment, Bentley Civil storm, BMPs