Excessive upstream to downstream land-use and deforestation, as well as downstream local sand mining along Indonesian rivers, which started in the 1990’s, triggered significant river surface runoff and flow increases, unbalanced sedimentation, aggradations, and degradation. These interacting effects resulted in unpredictable changes of river morphology, leading to flooding and infrastructure instability problems in most Indonesian rivers. Considering the serious impact of flooding and infrastructure damage, river sedimentation problem research is necessary in order to furnish preliminary assessment guidance for river channel capacity normalization and estuary management to prevent estuary aggradations. The novelty of this proposed research is to develop a more accurate river discharge flow calculation and estuary sedimentation prediction and analysis, taking into account river morphology changes based on thorough and meticulous sedimentation process investigation.
Without a comprehensive detailed knowledge of sediment transport and the sea water tidal processes, it would be impossible to analyze downstream river and estuary morphology changes accurately. The research team of this project will focus on the Bengawan Solo River by taking into account river morphology. Collaboration with the U.S. partner is expected to strengthen the Indonesian team’s ability to better predict and analyze the estuary sedimentation problems and analytically predict downstream and estuary flooding, infrastructure failure, and channel port aggradation due to changes in river morphology. The research project results will be disseminated to the East Java Ministry of Public Works to provide preliminary assessment guidance for river channel capacity normalization and estuary management to prevent estuary aggradations. Collaboration between the Indonesian team and the U.S. partner is aimed at promoting knowledge transfer, training, and advancement for Indonesian researchers.
 |  |  |
| Local cattle graze near the banks of a river after floodwaters have receded (photo courtesy of Dr. Soemitro). | The team conducts hydrology and bathymetry surveys in a variety of conditions (photo courtesy of Dr. Soemitro). |
After a preliminary site survey of the upstream section and an investigation into the river and embankment characteristics of the downstream section, the research team investigated the water depth. They then undertook field and lab-based geotechnical investigations of the estuary area, as well as analyzed nearby infrastructure (bridge and river dike) conditions and hydraulic characteristics of the river estuary. PEER funds also allowed Dr. Soemitro and her team to purchase a Strata Box HD to investigate the sub-bottom profile of the river.
The PI and a fellow researcher took part in the International Conference on Geotechnical Engineering for Disaster Mitigation and Rehabilitation in Kyoto, Japan, early in the grant period. Researchers also collaborated with Universitas Teknologi Sumbawa and presented a guest lecture on the findings to Kumamoto University in Japan.
In the final phase of the project in 2018, most activities were devoted to dissemination to share research results publicly and obtain feedback from government stakeholders and scientific colleagues. The PI Dr. Soemitro and her team received several useful comments from the dissemination event held January 19, 2018, at the Research Center of Bengawan Solo River Management (Balai Besar Wilayah Sungai Bengawan Solo, BBWS). Government officials recommended that the research team make an intensive study of the appropriate protection of the embankment of the Bengawan Solo River and further investigate the influence of coastal and marine factors on sedimentation in the estuary area. Based on requests made at this event and at a previous dissemination session at the Research Center for Water Resources in January 2017, an advanced dissemination workshop was conducted February 1, 2018, at the Coastal Research Center of the Ministry of Public Works and Public Housing. Officials there were very interested in collaborating with Dr. Soemitro’s team, particularly on the modeling of estuary sedimentation and high sea waves. The research team shared project results with the East Java Ministry of Public Works to provide preliminary guidance for river channel capacity normalization and estuary management. The researchers also disseminated their findings to fellow scientists and to other government stakeholders, including the Ministry of Public Works and Housing at Bandung and the Development Planning Agency of the Sumbawa District, receiving feedback on the results and suggestions for further research.
Dr. Soemitro also visited three universities in the United Kingdom to collaborate with colleagues and present lectures. The team’s collaboration with the U.S. partner, whom they visited in October 2018, strengthened their ability to better predict and analyze the estuary sedimentation problems and predict downstream and estuary flooding.
Publications
R. A. A. Soemitro, F. Adriati, D. D. Warnana, T. Mukunoki, R. Soetanto & M. A. Maulana. 2021. Sediment consolidation in ephemeral river: the effect of applied loading on soil properties and dredging method selection.
International Journal of River Basin Management, 19:3, 297-306,
https://doi.org/10.1080/15715124.2020.1742135Mahendra Andiek Maulana, Ria Asih Aryani Soemitro, Toshifumi Mukunoki, Nadjadji Anwar. 2018. Suspended Sediment Concentration Assessment as a Precursor to River Channel Shifting in the Bengawan Solo River, Indonesia.
Jurnal Teknologi (Sciences and Engineering) 80:5, September 2018.
https://doi.org/10.11113/jt.v80.11318Andi Patriadi, Ria Asih Aryani Soemitro, and Dwa Desa Warnana. 2016. Preliminary Assessment to Sediment Evaluation on the Estuary of Bengawan Solo River. In Proceedings of the International Conference on Problematic Soils and Ground Improvement (Soft Soils 2016), Bandung, Indonesia, September 2016.
Yerry Kahaditu Firmansyah, Ria Asih Aryani Soemitro, Dwa Desa Warnana. 2016. Preliminary Assessment to Bengawan Solo River Embankment Stability. In Proceedings of the International Conference on Problematic Soils and Ground Improvement (Soft Soils 2016), Bandung, Indonesia, September 2016.
Ria Asih Aryani Soemitro and Runi Asmaranto. 2015. The effect of drying-wetting cycles to the Wischmeier soil erodibility factors. Japanese Geotechnical Society Special Publication 2015, Volume 2, Issue 15, Pages 595-598.
https://doi.org/10.3208/jgssp.INA-06Ria Asih A. Soemitro and Dwa Desa Warnana. 2014. River Water Fluctuations Induced River Embankment Stability. In Proceedings of the Fourth International Conference Geotechnical Engineering for Disaster Mitigation and Rehabilitation, Kyoto, Japan, September 2014.
