Selangor to review approved projects, tighten flood mitigation requirements in high-risk areas

Selangor plans to review all development approvals previously granted by the state government. The review focuses on projects in high-risk areas, where flood-mitigation systems must work properly. It matters because weak or incomplete drainage measures can leave nearby communities exposed when heavy runoff arrives.

A new requirement could make developers construct temporary water-retention facilities. These facilities would hold excess water during construction or periods of intense runoff. Amirudin Shari also warned that developers must not carry out the work in a shoddy or substandard manner. The review therefore covers both approval conditions and implementation quality.

The measure follows flooding concerns in places including Johan Setia, Parit Mahang, Bukit Kuching, and Bukit Hijau. The state government is also examining vandalised embankments and overflow from the West Coast Expressway. The review could lead to stronger conditions, enforcement, and flood controls for future and already-approved developments.

Temporary water-retention facilities are spaces built to hold excess water for a limited period. They may include temporary ponds, basins, or other storage areas. Their purpose is to prevent large volumes of runoff from moving into streets, buildings, rivers, or already saturated drainage channels at once.

The key mechanism is delayed release. Water collects in the facility during heavy rain or construction-related runoff, then leaves more gradually as surrounding drainage systems can receive it. This reduces the speed and volume of water reaching low-lying places. The article does not describe a specific design, but Amirudin proposed requiring developers to construct these facilities.

The requirement matters because development projects can alter how water travels across land. Selangor will review earlier approvals and require better safeguards in high-risk areas. Developers must also ensure the facilities are built properly, since substandard work would provide little protection during flooding.

Two locations have already been identified for gazetting as water-catchment areas or floodplains. Gazetting would formally reserve those sites for managing and receiving water. This matters because protected land can help preserve space for runoff instead of allowing development or illegal activity to obstruct natural drainage.

The locations are connected to flood problems in areas such as Johan Setia, Parit Mahang, Bukit Kuching, and Bukit Hijau. Amirudin said several illegal operations in the area would face action, and demolition exercises would be necessary. Removing those operations would help make the sites available for their intended water-management role.

The District and Land Office will carry out the process with local authorities. The article does not name the two locations, so their identities cannot be specified from the available information. Their identification shows that the state is combining land-use controls with repairs and enforcement to reduce flood exposure.

A building does not need to stand beside a river to flood. Water can travel across connected low-lying land when a river or drainage system overflows. If the building is lower than surrounding ground, runoff and overflow may collect there before finding an outlet. This makes location within a flood pathway important, not just distance from a river.

Amirudin explained that the affected mosque receives overflow from the Subang River. That water flows toward Merbau Sempak, eventually reaches the Sungai Buloh river system, and arrives in the area. The mosque is therefore affected by water moving through the wider basin rather than by a nearby riverbank alone.

The state government will consult the mosque’s management about raising the structure or relocating it. The example shows why flood planning must consider natural water movement across a whole area. Buildings in low-lying pathways may need structural changes or a different site.

Flood embankments are meant to help contain or direct water. When they are vandalised and lowered below their original specifications, their protective height and effectiveness are reduced. Water can then pass over or around vulnerable sections more easily. This can expose nearby settlements and add to flooding when river levels or runoff rise.

The Sungai Buloh 1 Flood Mitigation Scheme has embankments affected by vandalism, according to Amirudin. He also identified water overflow originating from the West Coast Expressway. These two problems can combine: weakened flood structures may fail to control water, while additional overflow supplies more water to already vulnerable areas.

The state government has requested immediate action on the vandalism issue. It will also act against illegal operations, with demolitions planned in some places. Those sites may be gazetted as water-catchment areas or floodplains. Together, repairs, enforcement, and land protection could reduce future flood pressure.

When a building occupies a low-lying flood pathway, authorities have several possible responses. They can raise the structure so floodwater is less likely to enter. They can also relocate the building to a more suitable site. A third approach is to protect surrounding land so it can receive and manage water rather than forcing it toward buildings.

For the frequently flooded mosque, Selangor plans to consult its management about raising the structure or moving the place of worship. The flooding occurs because the site receives overflow from the Subang River. Elsewhere, the state plans demolitions so selected sites can be gazetted as water-catchment areas or floodplains.

These options address both the building and the landscape around it. Raising or relocating a structure may reduce direct damage. Protecting catchment land can preserve space for water. The article does not state which option will be chosen for each site, but consultation and local authority action are planned.

In a river basin, water from higher ground generally runs downhill toward lower areas. It may enter streams and rivers, join larger river systems, and eventually move toward the sea. Amirudin described runoff from Gombak or Petaling flowing toward Ijok or Kuala Selangor. This pattern has existed for a long time, he said.

The Subang River example shows how connected the system can be. Overflow moves toward Merbau Sempak, reaches the Sungai Buloh river system, and arrives in the affected area. Water keeps seeking an outlet to the sea, but the nearest coastline mentioned is in Kuala Selangor. Low-lying places can therefore receive water from distant areas.

Development can change this movement by placing projects in flood pathways or failing to provide proper retention facilities. Lowered embankments and illegal operations can further weaken protection or obstruct catchment land. Reviewing approvals, improving temporary storage, and protecting floodplains can help keep water-management systems effective.