Flushing Methods in Polder Drainage System to Obtain Better Environment Quality

Abstract

The Banger Polder is a polder system which covers an area ofaround 670 hectares in Semarang city. There are about 90,000 inhabitantsliving in this area. The Polder area is vulnerable to flooding caused by highwater levels during high tide and more during heavy rain. Climate changewhich may cause high sea level forms a serious threat for the coastal areasin Semarang as delta area. Objectives of the paper are to create causerelation flowchart, to analyse flushing zone, and to plan implementationand maintenance of flushing system. Regarding the research methods forimplementing the case, there are seven parties interviewed and observedrelated to flushing program. The parties are described with their interests, influence and (optional) negative impacts of stakeholders. The Causalrelation tree of flushing process is divided into 5 different steps:innovative, quality effect, operational effect, qualification effect, andmonitor effect. According to the observation and interview result, flushingzone in Banger polder area can be divided into 5 zones which areimplemented by some institutions; SIMA, PSDA, BBWS and Bappeda. Agood implementation and maintenance is needed to maintain the flushingsystem.