Bart Schultz
This involved significant input from the Netherlands, particularly from the consulting firm Witteveen + Bos for the design and from the Principal Water Authority of Schieland and Krimpenerwaard for the institutional aspects. From UNESCO-IHE, we also had a certain involvement regarding the drafting, in a more general sense, of Guidelines for water management and flood protection in urban polders. In this regard, we also took Semarang and the proposed Banger Polder as examples.
The Banger area is an urban district in Semarang bisected by a river also named Banger. In the East, the area is bordered by the Eastern Flood Canal (Banjir Kanal Timur), in the West and South by other districts of Semarang, and in the North by port areas and the Java Sea. Although flood protection measures existed around the area, the fact that the Banger River was in open connection with the Java Sea via its mouth into the Eastern Flood Canal, and the significant annual land subsidence within the area itself, caused inundations and floods to occur with increasing frequency. Consequently, impoldering and the construction of a discharge sluice or a pumping station to discharge excess water became necessary.
During the preparation for the measures to be taken, it became apparent that land subsidence in the area was occurring so rapidly that the construction of a discharge sluice, which would allow excess water to be discharged during low tide, was effectively pointless, as this would only be sufficient for a limited number of years. Therefore, it was decided to proceed immediately with the construction of a pumping station.
Regarding the institutional aspects, prior to the creation of the polder in 2010, a type of Water Authority was established under the name Badan Pengelola Polder Banger SIMA (BPP SIMA), along with a clearly defined set of duties, including the levying of contributions from stakeholders - residents and businesses - to cover the costs of management, operation and maintenance.
By 2016, the pumping station had been completed, and the Banger area was indeed a polder of 675 hectares with approximately 90,000 inhabitants. The pumping station is situated at the mouth of the Banger River into the Eastern Flood Canal, through which the pumped out water is discharged further into the Java Sea. The pumping station has a capacity of 6 cubic metres per second, which amounts to a water layer of nearly 8 centimetres per day, calculated over the surface area of the polder.
The formal opening of the pumping station took place on November 23, 2016, in the presence of Indonesian and Dutch dignitaries, including Indonesian Minister of Public Works and Housing Mochamad Basoeki Hadimoeljono, Mayor Hendrar Prihadi of Semarang, Dutch Prime Minister Mark Rutte, Minister of Infrastructure and the Environment Melanie Schultz-Van Haegen, and Hans Oosters as representative of the Dutch Water Authorities. The latter was particularly present because the Principal Water Authority of Schieland and Krimpenerwaard provided significant input into the establishment of the polder administration and the associated management, operation and maintenance regulations.
A study conducted since then has shown that there is satisfaction with the technical realization of the polder and that the regular inundations and floods have come to an end. However, there is less satisfaction regarding management, operation and maintenance. For instance, it appears that residents are still depositing a significant amount of waste into the watercourses, leading to blockages at culverts and at the pumping station. Furthermore, considerable odours occur during the dry season. Residents are also still contributing insufficiently to the actual maintenance.
Another problem is that decisions regarding water management appear to be made too much in a top-down manner, resulting in issues regarding involvement in the realization process and ensuring that the objectives to be realized are not sufficiently addressed.
Let us hope that the problems can be resolved in the near future, because for a polder, proper management, operation and maintenance of the water management system and flood protection provisions are an absolute prerequisite.
