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Urban development has resulted in an increase in impermeable surfaces, increasing the risk of runoff inundating the road network. This situation occurs in the drainage system on Jl. Letjend S. Parman, Jl. Emo Kurniaatmaja, and Jl. Pulau Banda, Pasirkareumbi Village, Subang Regency. This study aims to evaluate the hydraulic performance of existing channels and develop redesign guidelines to reduce the risk of local flooding. The methods used include hydrological analysis of daily maximum rainfall data from the Subang rainfall station, rainfall frequency analysis using the Generalized Extreme Value (GEV) distribution, Intensity-Duration-Frequency (IDF) curves, and hydrological and hydraulic simulations using the Storm Water Management Model (SWMM). Model parameters include sub catchment area, rainfall intensity, time of concentration, infiltration using the Curve Number method, channel dimensions, cross-sectional shape, channel material, and the Manning coefficient. The results indicate that the GEV distribution provides a good fit for determining design rainfall. Based on the typology of a metropolitan city and a catchment area of ​​26.04 ha, the modeling period is 2 to 5 years. The SWMM simulation results indicate that some channel segments have very high flow velocities, potentially causing scour, while other segments have very low velocities, potentially causing sedimentation. This confirms the need for evaluation and restructuring of channel dimensions and slopes to improve the hydraulic performance of road drainage and reduce localized flooding.

The development and revitalization of the Sungai Asam drainage system in Jambi City face serious problems in the form of river sedimentation and limited channel capacity, which trigger flooding. These conditions necessitated a design change for bank protection from revetment to a retaining wall (Dinding Penahan Tanah/DPT) in the SA223 to SA228 segment. This study aims to analyze the construction cost and implementation duration of the DPT resulting from the design change. The theoretical framework covers retaining wall concepts, cost estimation (Bill of Quantities), and construction project scheduling. A descriptive-analytical method was applied using secondary data, including design drawings, work volumes, the 2025 Water Resources and Human Settlements Unit Price Analysis (AHSP), the 2025 Jambi Provincial Standard Unit Prices, and time analysis using the S-Curve and Critical Path Method (CPM). The results indicate that the total construction cost of the DPT in the SA223–SA228 segment is IDR 9.524.259.092,02, while the project duration is determined based on the critical path identified through CPM analysis. The discussion confirms that the design change significantly affects work complexity, construction costs, and schedule adjustments. The study concludes that systematic and measurable cost and time analyses are essential as a technical basis for decision-making in river revitalization projects to ensure effectiveness, efficiency, and the sustainability of flood control infrastructure.

This study is motivated by the high frequency and significant impacts of flooding in Indonesia, particularly the recurrent flooding of the Kali Lamong River in Gresik Regency, which causes substantial socio-economic losses each year. Although disaster management is normatively regulated by national policies, its effectiveness depends largely on collaborative governance among multiple actors. This study aims to analyze the practice of collaborative governance in flood mitigation in Gresik Regency using the model of Weber, Lovrich, and Gaffney (2005), which includes vertical, horizontal, and partnership dimensions, and to identify the key challenges that hinder its implementation. A descriptive qualitative approach was employed in flood-affected areas along the Kali Lamong River, involving BPBD, DPUTR, sub-district governments, village authorities, and local communities through interviews, observations, and document analysis. The findings reveal that collaboration has been established and functions relatively well, particularly in hierarchical coordination, division of roles among government agencies, strengthening of Destana, KENCANA, and SPAB programs, as well as CSR involvement and community participation all contributing to reduced flood duration. However, the implementation of collaborative governance remains constrained by slow land acquisition and infrastructure development, a predominantly reactive orientation, suboptimal early-warning systems between upstream and downstream areas, and uneven support from the private sector and academia. The study concludes that strengthening collaborative mechanisms and accelerating the resolution of structural barriers are essential to achieve more sustainable flood mitigation efforts in Gresik.

The coastal area of Manado City, particularly the estuary of the Bailang River in Bunaken District, frequently experiences inundation due to the complex interaction between river discharge and tidal fluctuations. This study aims to analyze the spatial distribution and extent of flooding resulting from the combination of river discharge and tides, as well as to evaluate mitigation strategies based on numerical modeling results. A two-dimensional hydrodynamic model was developed using MIKE 21 Flow Model FM HD, utilizing topographic and bathymetric data from DEMNAS and BATNAS, along with 2023 river discharge and tidal data. Simulations were conducted for existing conditions, minimum discharge with maximum tide, and maximum discharge with maximum tide. The results show that tidal influence significantly contributes to the increase in flood extent and duration, especially when high river discharge coincides with peak tidal conditions. The most affected areas are Kelurahan Molas and Tumumpa, located along the riverbanks and near the fish auction port, with inundation covering up to 4.973 hectares and water depths exceeding 0.5 meters. Recommended mitigation strategies include river normalization and the implementation of a real-time hydrodynamic early warning system. This study supports flood risk management and coastal spatial planning, serving as a technical reference for local government policy-making.

The problem of waste, especially inorganic waste, is becoming an increasingly serious environmental issue in Indonesia, including in the Tunas Bangsa Orphanage. Lack of awareness and skills in waste management has an impact on environmental pollution and the potential for flooding. This leadership project activity aims to build environmental awareness in the children of the Tunas Bangsa Orphanage through education and training in waste management into appropriate products. The methods used include observation, preparation of tools and materials, implementation of education and practice in making flower pots from used bottles, and evaluation through Focus Group Discussion (FGD) with supervising lecturers, administrators and children of the Tunas Bangsa Orphanage. The results of the activity show that this leadership project not only increases the knowledge and skills of children in managing waste, but also fosters awareness and concern for the environment. In addition, this activity encourages the creativity and independence of the children of the orphanage. However, the evaluation also shows that it is necessary to extend the duration and sustainability of the program so that the benefits obtained can be more optimal. Overall, this leadership project is relevant as an educational and solution-oriented effort in overcoming the problem of waste and building environmental awareness from an early age.

The road paving and ditch construction project in Balun Ijuk Village, particularly from Sahpire Boarding House Lane to Jerambah Gantung Road, aims to enhance transportation infrastructure to support mobility for local residents and students of Bangka Belitung University. This study employs a quantitative method with a financial feasibility analysis approach. Findings indicate that the total project cost is IDR 988,153,778 with an implementation duration of 2 months and 3 weeks. The financial analysis yields a Net Present Value (NPV) of IDR 481,705,602.62 (15%) and IDR 326,419,561.97 (20%), an Internal Rate of Return (IRR) of 18%, a Benefit Cost Ratio (BCR) of 1.48, and a Payback Period (PP) of 2 years and 7 months. Based on these results, the project is deemed economically viable with significant positive impacts on the community, including improved accessibility, reduced flooding risks via effective ditches, and enhanced connectivity and local economic activities. Additionally, the project implementation is expected to create temporary job opportunities and support sustainable infrastructure development in the region.

Annual flooding in Malang City caused by overflow from Kadalpang Dam indicates the impact of limited understanding of flood threat classification. This study is a qualitative research conducted to describe and analyze the flood phenomena experienced by exposed residents. A qualitative approach was chosen because it allows in-depth data collection on individual and group experiences related to flooding, including attitudes, perceptions, and coping strategies used in facing the situation. The results of the study show that the flood threat level classification from Kadalpang Dam based on the flood river index (KB), flood duration (LB), and flood height (TB) against the exposed population index is high. Areas classified as having a high flood threat level tend to experience significant impacts, such as infrastructure damage, loss of property, and risks to public safety and health. This study provides a deeper understanding of the complexity of flood problems in the local context, while also supporting efforts to improve mitigation and adaptation strategies to reduce the negative impacts of this natural disaster.