Climate change is causing sea rise resulting in coastal erosion, flooding, and threatening ports and cities. Jakarta is in extreme danger: thirteen rivers run through the city, causing frequent flooding. The mega-city of 10 billion is doubly endangered: urban land is suffering subsidence, parts of Indonesia’s capital (some predict 95%) could be deluged by 2050.
Even rivers like the Thames and Lea in London are not immune. But the city of London Bridge is responding. Thames21 is planting reeds that oxygenate rivers, restoring the habitat marred by pollution; reeds convert toxic ammonia to nitrate. Reed beds also provide habitat for aquatic life. In an echo of the Canal des Deux Mers, the canalized section of the River Lea will receive new reed beds every 300 meters over the length of the river coursing through London.
Meanwhile, Jakarta is exploring response including artificial recharge, a method used a half-century ago by Tokyo in a time of subsidence; to support the program, groundwater extraction was halted and businesses were required to utilize reclaimed water. Jakarta would need to use only rainwater; could catchment systems help? The Dutch, formerly involved in the region, have returned: Institute Deltares reported on the efficacy of the current plan to build the Great Garuda Sea Wall (32 km) along with 17 artificial islands at the cost of (US$) 40 billion. Included in the plan is a new lagoon waterway that can be lowered during floods allowing water to drain. Another method: biopori – digging a hole of 100cm depth to allow rainwater to more easily absorbed into the land, replenishing groundwater. Indonesia may offer an example to many places in the world surrounded by water; how can we build better coasts?
“Jakarta, the fastest-sinking city in the world.” 12 August 2018. By Tom de Souza, with interactive elements by Arvin Surpriyadi, Davies Surya, and Leben Asa.
“Project Reed Beds.” Thames 21. https://www.thames21.org.uk/project-reedbed-2/
Building the World Blog by Kathleen Lusk Brooke and Zoe G Quinn is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported Licen