The main goal for this project was to  assess and design sustainable, economical and environmentally sound storm water management system that minimizes the potential threats of urban flooding and protecting natural drainage features with following specific objectives:

  • Assess for existing drainage system using SWMM, check for adequacy of existing and recommend possible solutions.
  • Meet all applicable international and national regulatory requirements for stormwater management system.
  • Maintain existing stormwater management infrastructure and provide sufficient infrastructure capacity to meet the future needs of the Thimphu Thromde (2020-2030)
  • Protect the natural drains and stream in the study area.

Provide sustainable stormwater management program incorporating low impact development techniques where physically, economically and practically possible including detail design and drawings.

Following were the major scope of the assignment:

  • Review of relevant national and international literatures, reports and future urban development plan if any, information on past initiatives and guidelines relevant to storm water management plan to understand the considerations and uncertainties.
  • Assess existing stormwater network through the identification of problems or critical portion of the network and analyzing existing level of services and performance of the network.
  • Downscaling of climate data and analyses them to understand future climate change scenarios for the project area.
  • Delineation of the watershed area using ArcGIS tool from client provide DEM, stream network, inlet and outlet point.
  • Frequency analyses of hydro meteorological data and for design storm event selection.
  • Development of SWMM model for the existing stormwater network in the project area, calibrate it and then simulate for both present and future conditions.
  • Assessment of adequacy of the existing stormwater network for both present and future and recommend suitable interventions (both structural and non-structural).
  • To develop different alternatives by simulating it in SWMM model incorporating different recommend interventions and climate change and future urban development scenario.
  • Development of strategies on the basic of options analysis and identify preferred strategies for sustainable stormwater management.
  • Recommend a stormwater management program for the Thromde to implement that will meet the desired levels of services, targets for compliance with regulations and guidelines
  • Develop an integrated stormwater management plan that address both current and future stormwater in the city.




Flood and Engineering Division, DES, MoWHS


December 2019 – October 2020