Recommendations for planning water infrastructure in the Surabaya City area with the influence of watershed characteristics to realize sustainable settlement drainage that is safe from flooding

The development of urban areas often has an impact on changes in the surface run off area of water flow, a consequence that often occurs is flooding due to an increase in the value of run off drainage from housing/industries which burdens the capacity of urban land drainage channels. The analysis carried out is to calculate the value of the travel time (Tc) from the build area compared to the peak time (Tp) in the urban partial drainage flow. The value of time concentration is influenced by the slope of topography and watershed area of each rayon in Surabaya. The calculated Tc and Tp values will be combined to find the linear correlation value of the effect of watershed characteristics on development/change of land area in Surabaya. The results of the linear analysis of the relationship between the area of the build up area and the combined travel time in each rayon are not the same, this is due to the influence of land topographic slopes in each rayon and also the area of the watershed be different. the length of the channel on the drainage of urban area in each rayon have a separate drainage network sub system from one another. This is a consideration that the determination of the formulation of the relationship between the area of the build up area and the time and volume of the reservoir must adjust the characteristics of each rayon.