The causes of flooding from rainwater and wastewater in Vietnamese cities are usually: inadequate drainage system; the original design did not match; runoff coefficient in drainage basin increases due to change of cover surface; leaking water supply pipe; clogged drains, sediment; damaged drainage works; incidents at pumping stations to drain rainwater and wastewater; due to climate change leading to increased rainfall and irregular urban hydrology, sea-level rise, etc. Therefore, the selection of hydrological and hydraulic models applied in urban drainage is necessary to study and apply scientific and technical advances in the field of drainage including hydrological analysis, network hydraulics drainage and propose effective drainage solutions for new planning and upgrading areas.