STUDY OF PUMP AND RETENTION BASIN REQUIREMENT FOR SEMARANG-DEMAK COASTAL DIKE PLAN, CENTRAL JAVA

Abstract

Semarang city in East Java, Indonesia, is frequently inundated on its northern side due to
coastal flooding which is mainly caused by land subsidence. A study by the government to prevent this
coastal flooding was started in 2014 and resulting comprehensive solution that ultimately will make 8 km of
Semarang coastal area protected by the coastal dike. This leaves the area behind the coastal dike as a polder
and hydraulic analysis is critical to ensure the polder areas will not be flooded when extreme rainfall occurs
in the area. This study analyses the pumping capacity and retention basin configurations based on the official
watershed agency (BBWS Pemali Juana) by performing hydraulic simulations and the result shows that the
current configuration is relatively minimalist compared to the solutions suggested to other urban areas in the
world. Recommended pump and basin configurations with higher flood-draining performance are given in
this study based on the past design experience from the capital city of Jakarta as well as similar cases from
other urban areas.