UNS — Disaster Study Center (PSB) LPPM Universitas Sebelas Maret (UNS) Surakarta held Online Discussion Serie 7 on “Banjarmasin Vs Pekalongan Floods” on Saturday (27/3/2021). The discussion was attended by 257 participants through the Zoom Cloud Meetings and marked PSB online activities in 2021.
Dr. Yasin Yusup, S.Si., M.Sc., one of PSB UNS experts, attended the event as a moderator. Dr. Yasin Yusup stated that this discussion tried to bring new perspectives and compare the similarity and differences between the Banjarmasin flood and Pekalongan flood regarding its characteristics, factors, and impacts. The discussion was opened with material on “The Causes and Impact of Floods in the City of Banjarmasin” delivered by Dr. Sidharta Adyatma, M.Si. as the Chief of Disaster Mitigation Study Center Universitas Lambung Mangkurat (ULM) Banjarmasin.
The Geography Education teacher in ULM explained that the Banjarmasin flood was affected by the La Nina phenomenon. In terms of meteorological factors, there are several aspects that caus floods, for example, temperature, air pressure, wind, cloud, and precipitation. In his presentation, Dr. Sidharta used the Ventusky application to browse big data factors and showed that on 7 January 2021, Kalimantan had a high temperature because of the increased agricultural activities that open new farming ground by burning the existing plants. Similar data is observed on 12-13 January 2020 at 14.00 WIT (Eastern Indonesia Time). This temperature affects the air pressure, causing wind that brought clouds over Banjarmasin.
“The clouds concentration will affect the precipitation. And the problem, Kalimantan becomes the center with its low pressure,” Dr. Sidharta said.
In terms of bio-geo-physic, Dr. Sidharta emphasized the human factor and land degradation caused by rapid land conversion, such as converting rubber plantations into oil palm plantations. The number of secondary forests, paddy fields, and shrubs is declining, while plantation lands increase to 219 thousand ha. Forest is also converted into a mining area, as shown by the government mining permit for 11,334 Ha area between 2015-2020. These changes, for example, have caused a flood in the Barito River watershed. Dr. Sidharta added that the watershed has Drainage Density higher than 0.365, which poses medium to high flood risks.
The second speaker was Dr. Pipit Wijayanti, S.Si., M.Si., a Hydrologist from PSB LPPM UNS. Dr. Pipit delivered material on flood and tidal flood in Pekalongan District, which caused degradation of settlement, agricultural land, environment, and water resources. Pekalongan District has a 7.2 km sea wall built in 2018 and was planned to last for the next ten years. However, three years from its establishment, the wall has failed to prevent the tidal flood in 2021.
Dr. Pipit added that Pekalongan District is a high ground in the southern parts and coastal in the northern regions. Pekalongan District has two watersheds and a high subsidence level with 3-4.8 cm, despite not being a large city. Subsidence, land surface, and sediment materials will increase the risk of floods and tidal floods.
“The factors that in work are fluvial sediment affected by rain, debit, material, and watershed area. Coastal sediment affected by coastal currents, coastal waves, tides, deposition mechanisms in coastal areas, and sea-level rise,” Dr. Pipit said.
Prof. Dr. Eng. Syamsul Hadi, S.T., M.T. (LPPM UNS Secretary), who represents Prof. Okid Parama Astirin (Chief of LPPM UNS) appreciated the discussion and stated that LPPM will fully support PSB events. Prof. Syamsul hopes that PSB UNS could take part, contributes, and benefits disaster mitigation in Indonesia. Humas UNS
Reporter: Kaffa Hidayati
Editor: Dwi Hastuti