Urban flooding has become an increasingly critical challenge in Indonesian cities, exacerbated by climate change, rapid urbanization, and deteriorating conventional gray infrastructure. Green infrastructure emerges as a transformative approach to urban flood management, offering multifunctional benefits beyond traditional drainage systems. However, successful implementation faces significant governance and financing barriers. This conceptual paper examines governance models and financing mechanisms for green infrastructure deployment in Indonesian urban contexts, with specific focus on flood mitigation. Through synthesis of international best practices and Indonesian policy frameworks, this study proposes an integrated blue-green-gray governance model that combines nature-based solutions with engineered facilities. The analysis reveals that Public-Private Partnership schemes, combined with innovative financing instruments such as green bonds, land value capture, and climate funds, can address the infrastructure financing gap while ensuring long-term sustainability. The paper contributes to urban planning discourse by proposing a strategic framework that integrates fiscal policy, spatial planning, and multi-stakeholder governance for enhanced flood resilience. Findings suggest that decentralized implementation coupled with strong central coordination, clear regulatory frameworks, and community engagement are essential for effective green infrastructure deployment. This research offers actionable insights for policymakers, urban planners, and infrastructure developers in advancing sustainable flood management strategies aligned with Indonesia’s climate adaptation goals and the 2045 vision
In Costa Rica, water supply networks provide water to over 94% of the country's population. However, only an estimated 14% of wastewater receives proper treatment. The lack of centralized sanitation infrastructure has resulted in the use of septic tanks and the discharge of untreated greywater into rivers, causing environmental degradation of surface waters. Retrofitting conventional centralized sewer networks and treatment plants into the existing urbanization presents extensive social, economic, and technical challenges. Nature-based Solutions (NbS) for greywater treatment can reduce pollutant loads and improve the environmental status of water resources and represent an opportunity for technical leapfrogging towards sustainable, decentralized on-site treatment and reuse. However, the implementation of NbS in urban areas poses significant challenges due to the complex interplay of social, regulatory, and economic factors. Specifically, for on-site greywater treatment systems, meeting several criteria, including efficient pollutant removal, affordability, and public acceptance is essential for successful implementation and operation. This study assesses the technical, socio-economic, and political-regulatory dimensions relevant to implementing NbS for decentralized greywater treatment. To conduct this research, a Real-World Lab was established in the Great Metropolitan Area of Costa Rica, employing a transdisciplinary approach. This approach provided a physical space and societal context to integrate site-specific aspects and understand the various factors that influence the implementation and upscaling of NbS. As part of our methodology, we analyzed the water quality parameters and treatment performance of a NbS prototype for decentralized greywater treatment. Within the Real-World Lab framework, we conducted interviews, surveys, and field observations to investigate socio-economic and political-regulatory aspects. Our results highlight the technical potential of the NbS prototype. However, the limitation lies in the governance scheme and financing mechanisms required for upscaling the NbS as a decentralized on-site technology across the country. Our multidimensional assessment provides insights into the requirements for widespread implementation of NbS, applicable to other regions facing similar retrofitting sanitation challenges.
Mathurin François, Marc Arthur Petit-Homme, Eduardo Cohim, SÃlvio Roberto Magalhães Orrico · 5 authors
Abstract The use of rainwater is a reliable alternative for reducing clean water consumption and water bills. This study assessed the willingness of Haitians to invest in rainwater infrastructure (RWI). A questionnaire with closed and open-ended questions was used for this purpose. For closed-ended questions, ‘0’ and ‘1’ were used for negative and positive answers, respectively. Other numbers were used to encode the open-ended questions. The two-tailed Z-test was used to compare two proportions, where a result was statistically significant when the p-value was less than 0.05. Of 362 rainwater users, 81.2% used it for washing, bathing, cooking, flushing, and drinking. Approximately 73.4% of households with 1–3 people, compared with 84.0% of families with 4–6 people, used rainwater. Of all the respondents, 82.3% would invest in RWI if the government agreed to finance up to 50.0% of the project. More than 73.0% of respondents in each locality would invest in rainwater in RWI under the conditions previously mentioned. It is concluded that the implementation of RWI and decentralization of water systems would be welcomed by the rainwater users in Haiti, but the unwillingness of the Haitian government could be the main barrier to such a transition.
Sjon van Dijk, Amanda W. Lounsbury, Arjen Y. Hoekstra, Ranran Wang
Many cities are confronted with both water scarcity and urban flooding as centralized water infrastructures becoming increasingly inadequate in a changing climate. Decentralized infrastructures like rainwater harvesting (RWH) can ease both issues. Yet, most studies find RWH offers limited infrastructure capacity at high cost. Previous assessments, however, fail to consider two critical advantages: multi-functionality and high adaptability. By improving the incorporation of these advantages in our analysis of 1.06 million buildings with distinct design and water demand characteristics and 20-year hourly precipitation records in New York City (NYC), we demonstrate, contrary to existing studies, that strategically designed, financed and implemented rooftop RWH systems in all or a subset of the buildings can meet large-scale infrastructure development needs for water supply and stormwater management. RWH implementation featuring public-private partnerships (PPP) in 43-96% of the buildings can serve 17-29% of the city's non-drinking water demands while reducing the public expenditure per unit of water supply by 13-85%. The distributed citywide RWH implementations prevent 35-56% of rooftop runoff from entering the sewage system, rivers, and/or waterways per month, with observed rooftop runoff reductions as high as 90% for a single rain event.
Martin Lang, Frederick Novotny, Mohan Jethwani, Charles Samowitz
The establishment of a centralized sewerage agency in 1963 has enabled the development of a program to upgrade and augment New York City’s sewer system to meet the vital life supporting needs of the 21st century. The previous decentralized structure, with five different design standards and financing assessments, did not lend itself to a rational and sound engineering approach to the drainage problems. The shift of population to the periphery of the city, the elimination of sewer assessment, and the antiquated sewerage mandated launching a crash effort. Citywide planning, new management techniques, infusion of new engineers, and optimal use of in-house staff and consultants have all culminated in sixfold acceleration of the sewer construction program.