River rehabilitation/ restoration

Assemini, a municipality in Cagliari, has long grappled with hydrogeological instability, marked by major floods in 1999 and 2002. To mitigate future risks, the municipality launched a series of interventions focused on improving the hydraulic management of its waterways. These projects are part of a broader strategy to address recurring flood hazards exacerbated by the effects of rapid urbanization in the 1970s, which disrupted the natural water drainage systems (1,3). The central goal of the project is to reduce the risk of flooding by enhancing the functionality of existing waterways. This includes both preventative measures and structural improvements to the canal system to manage stormwater more effectively. These efforts aim to safeguard urban and rural areas from severe meteorological events. The project development involved a multi-phased approach starting in 2013, focusing on cleaning and maintaining minor waterways such as the Gutturu Lorenzu, Sa Nuxedda, and Giaccu Meloni streams. These efforts expanded over time, culminating in an agreement with the Land Reclamation Consortium of Southern Sardinia in 2015, securing both local and regional financial support. The interventions have covered over 24 kilometers of canals and streams, targeting key flood-prone areas (1,2).
Key interventions include the cleaning and maintenance of over 35 km of canals and streams, in partnership with the Land Reclamation Consortium of Southern Sardinia, supported by regional funding. A separate, large-scale intervention in Truncu Is Follas involves constructing an open-air diversion canal, a retention basin (44,500 m³), and new pipelines to redirect floodwaters, thus reducing risk for residents downstream in both Assemini and Elmas.

For thousands of years the Rio Salado, also known as the Salt River, and its larger mainstem, the Gila River, served as an important perennial source of life and growth for indigenous people residing in central Arizona, including the Akimel and Piipaash (3). Today, the Salt River is an ephemeral river corridor connecting diverse urban communities across an expansive and growing Maricopa County (3). While the river is now typically defined by intermittent flow as a function of water conservation and distribution in an arid urban climate, it also has powerful flows during the Arizona monsoon season providing a diverse and unique ecosystem for the region (3). To foster the health of the River, a regional multi-decade project was initiated in 2018 called Rio Reimagined, which includes six cities and two tribal communities (1). Rio Reimagined is a planning initiative in a very early concept stage, centered around the mission to support and enhance this treasured river corridor (3). The goals of Rio Reimagined consist of connecting communities, Equitable & Sustainable Development, and Restoring and Revitalizing Healthy Rivers (3). As part of the Rio Reimagined, the City of Phoenix founded a collaborative project called Rio PHX that will help promote a 20-mile Rio Salado (Salt River) corridor as a local and regional destination that attracts positive investment for the benefit of existing/future businesses, residents, and tourists (1). The final aim with this project is to improve health outcomes for existing and future residents by address outstanding needs in the area and create opportunities for housing, employment, recreation, art, and ecological restoration (1). From May 2024 to May 2025 Rio PHX will engage in creating a community profile, an existing conditions assessment, community engagement & visioning, developing implementation strategies and drafting the master plan (1). Public hearings and final plan adoption are set to take place in fall 2025 (1).

Mapinguari National Park, located in the Amazon region of Brazil, is a protected area distinguished by its rich biodiversity and vast expanse of untouched tropical rainforest (2). It was officially created on June 5, 2008, by decree, covering an area of 1,776,914.18 hectares (2). The Chico Mendes Institute for Biodiversity Conservation (ICMBio) manages the park. It is linked to a management plan encompassing several nearby conservation units and their areas of influence (2, 3). Its main goal is to preserve the valuable natural ecosystems and scenic landscapes of the Purus-Madeira interfluvial region, which includes savanna enclaves (2, 3). The ecoregion where it is located has a high priority for botanical conservation due to parameters such as species richness and endemism (3). Additionally, the area presents great environmental heterogeneity, with several isolated and unique ecosystems, aspects that have been considered for fostering scientific research and public visitation, with programs for environmental education, recreation in contact with nature, and ecotourism (3). On March 8, 2013, an advisory council for the park was established to involve various stakeholders in decision-making and the effective conservation of the park (2), and in 2018 a Management Master Plan was established, seeking to develop an integrated approach for the protection and proper management of the region, especially considering the socio-environmental impacts of the construction of the BR-319 highway and the deforestation caused by fires, the expansion of soybean cultivation, land appropriation (7) and cattle ranching from the neighbouring state (3, 10). It was established as a Natural Park in 2008, but over the years it has undergone changes in land regulations, adding or decreasing its size as certain mining activities have been allowed in the buffer zone (2)

Rapid urbanization and a population density of 6,247 people per km² have placed significant stress on Nairobi's natural resources (Ref 1). The 40-km long Nairobi River Basin, originating from the Ondiri Swamp, serves as a vital water source for the city (Ref 1, 2). However, it has suffered severe pollution from untreated sewage, solid waste, industrial contaminants, plastics, and agricultural runoff (Ref 1, 3). This degradation has had a serious impact on the ecosystem, local residents, and biodiversity (Ref 3).

To address these issues, the Nairobi River Basin Programme (NRBP), sponsored by UNEP, was launched in 1999 (Ref 4). Since then, government and non-state actors have worked together on solid waste management, riparian restoration, and wastewater control (Ref 1). The program was implemented in two phases: Phase I (2003–2006) and Phase II (2006–2009), involving stakeholders from the government, private sector, and civil society (Ref 1, 4, 5). Despite these efforts, a study from 2017 found significant tree removal along the river, and between 1988 and 2014, encroachment into the 30-meter riparian buffer zone dramatically increased, particularly between 2010 and 2014, further degrading the river’s health (Ref 1).

The riparian forest of Montgérald, through which the “Monsieur” River flows, is located within Fort-de-France and boasts rich biodiversity, featuring around 100 species of shrubs and trees and about 30 animal species, including 16 types of birds. It is one of the last remnants of the mesophilic forest type and the only example in a French peri-urban setting. This unique ecosystem is recognized as a Natural Area of Ecological, Faunal, and Floral Interest (ZNIEFF) and a Classified Wooded Area (EBC), underscoring the need for conservation efforts.
Covering nearly 21 hectares, this site offers ecological benefits like air quality improvement and temperature regulation, providing a "fresh air island" near the city center. However, it faces significant challenges, including flooding caused by climate change and heavy rains, which exacerbate erosion along the Monsieur River. The area is also threatened by invasive alien species, making conservation measures even more crucial.
Since 2015, the municipality of Fort-de-France, along with project partners, has been working on developing this natural space for both conservation and public engagement purposes. The most recent actions occurred in 2020, including riverbank restoration, clearing invasive species, and creating walking paths and educational installations. Additionally, the project features an awareness campaign targeting local schools. The ongoing initiative aims to merge biodiversity conservation with community recreational use and environmental education, ensuring the resilience of this vital ecosystem against the impacts of climate change. (Refs. 1, 2, 3)

Chickasabogue Park, a 1,100-acre outdoor recreation facility and wildlife refuge in Eight Mile, Alabama, is the largest park in Mobile County (Ref 3). Since 2022, the park has undergone extensive renovations aimed at increasing public access to green spaces and shoreline recreational areas, particularly along Chickasabogue Creek, while offering a variety of outdoor activities in a natural setting and preserving local biodiversity (Ref. 3).
The improvements focus on enhancing the day-use area, including upgrades to the playground, a splash pad, basketball courts (adapted to heavy rains with water-permeable materials), and a ball field (Ref 1, Ref 2). Additionally, a new pavilion site and an events and interpretive centre are being developed (Ref 1, Ref 2). Sidewalks and family-friendly walking trails are being built, and improvements are also being made to the park's mountain bike trail and disc golf course (Ref 2), providing more opportunities for outdoor physical activities in nature. Other significant upgrades include the creation of a restroom and a new parking lot with permeable pavers to prevent flooding (Ref 2). Critical infrastructure work is underway, including the installation of underground utilities, water, sewer systems, and roadwork (Ref 2). Furthermore, a new Recreational Vehicles (RV) campground with 38 spaces is in the works (Ref 2).
These upgrades are part of a broader initiative aimed at ensuring the public can quickly access and enjoy natural resources (Ref 2). The renovation also emphasises the cultural heritage and historical significance of the park, with plans to use architecture, design, and artefacts to honour the different cultures that once lived in the area (Ref 2). The next phase includes seeking funding to renovate the beach area and construct a new boat ramp (Ref 1).

The Panke is a watercourse that rises outside Berlin and reaches the urban area of the city, flows through the districts of Pankow and Mitte and flows into the Berlin-Spandau Ship Canal in Wedding. The length of the Panke is around 29 kilometres. Almost the entire length of the Panke in Berlin (around 17.6 km) is to be renaturalised - on the section from the state border in the north of Berlin to its confluence with the Berlin-Spandauer-Schifffahrtskanal (BSSK). The Panke is currently a small watercourse that has been heavily remodelled by humans. In large parts of the watercourse, the banks have been straightened like a canal and reinforced with sheet piling, among other things. Existing riverbed drops and weirs prevent fish from travelling unhindered through the watercourse. Studies on water body (structural) quality, typification and other biological quality characteristics have shown that the Panke has poor status values in the majority of Berlin's sections, e.g. in terms of the fish population. The negative assessment results are primarily attributed to the lack of habitat and structural diversity, the lack of passability of the watercourse and, in some cases, high nutrient loads. (Ref. 1)

The restoration of the river was initiated by the State Berlin, following the European Water Framework Directive. The central aim is to implement flood plains and recreate the pre-straightened water course, to ensure space for flooding, habitats for more diverse flora and fauna, increase water flow for better water quality and create a site for recreation in a densely built city. (Ref. 1; Ref. 2) The project started back in 2003 and is expected to be finished in the 2030s (Ref. 2; Ref. 7).

The Rimac River Special Landscape Project, developed by the Municipal Programme for the Recovery of the Historic Centre of Lima (PROLIMA), is a municipal proposal that arose as a response to the significant degradation of the Rimac River as it passes through the historic centre of the Peruvian capital. The river has lost its character as a green corridor and potential public recreational space for citizens (1, 3). The main problems affecting the river are related to the erosion and risk of flooding of the river space, the ecological degradation of its channels and banks, the disconnection and low quality of adjacent public spaces and the urban fragmentation caused by car-oriented mobility (2). To recover its essence as an ecological green corridor, it was proposed to give back to the Historical Centre its riverside identity and to recover the water, environmental and scenic landscape. This project aims to restore the Rímac to its role as a geographical heritage and backbone of the city of Lima, creating a system of accessible and sustainable public spaces that will help to recover this water, urban and historical landscape, as well as providing a better quality of life for the residents and users of the Historical Centre (1).
The project consists of 4 stages of intervention: Puente del Ejército - Puente Santa Rosa / Puente Santa Rosa - Puente Balta / Puente Balta - Límite
of the CHL to the east (5). Among the interventions that make up the Special River Landscape Project are: the renaturation of the 4 km of the Rimac River as it passes through the city, the construction of 14 parks, 7 squares, 1 tree planting project, 24 street renovation projects, 7 bridges/pedestrian walkways, 10 building rehabilitations and 2 new public facilities (4). It is planned to start implementing the project by the end of 2024 (4).

A new landscape plan for the Santry River, developed since 2019, envisions it as “the backbone of a green infrastructure project,” designed to support nature, pedestrians, and cyclists. The project will create a continuous route from the Dublin Bay Biosphere at St Anne’s Park to the wider hinterlands of Dublin at Sillogue.
The plan proposes transforming the Santry River into an “integrated green-blue landscape for ecology and recreation,” incorporating a variety of sports, cultural, and leisure activities. Through an agreement with Fingal County Council and the National Transport Authority, Dublin City Council has commissioned studies to address the existing flood risks along the river.
The council’s goals for the Santry River include river restoration, flood mitigation, greenway development, and environmental protection, extending from the river’s origin in Harristown within Fingal County to its outlet at James Larkin Road. The project framework will span four years, with annual reviews and budget assessments.
The project team has engaged the public in early autumn of 2022 to gather input on these plans, as the Santry River project aims to create a vibrant River Park that integrates natural and recreational elements. Running through North Dublin, this new green-blue infrastructure will serve both ecological and community needs, offering opportunities for sports, culture, and relaxation. Ultimately, it will form a natural corridor linking the Dublin Bay Biosphere at St Anne’s Park with Sillogue, promoting biodiversity while enhancing accessibility for pedestrians and cyclists (2).

Perch Creek is one of the many meanders that drain into Dog River (Ref 2), located just west of Mobile Bay (Ref 3). These areas include sensitive, tidally influenced marshes and flats where the brackish water of the Bay meets fresh waters (Ref 1). The Perch Creek Nature Trail & Preserve project aims to protect 96 acres on Perch Creek (Ref 3). It is part of efforts to revitalise Mobile’s coastal community and improve the water quality of the city's urban river (Ref 2), following the devastation of the BP oil disaster in 2010.
The project focuses on two main aspects: creating a low-impact recreational destination to spark economic redevelopment, and preserving Mobile’s coastal wetlands (Ref 1).
The conservation aspect involves wetland acquisition, marsh restoration, and invasive species management, improving water quality in both waterbodies (Ref 1). The area, rich in wildlife, requires habitat protection, including for migrating birds, foxes, alligators, manatees, and bald eagles (Ref 1). Brackish marshes on the property serve as nurseries for fish, while forested areas provide natural corridors for wildlife (Ref 3). The wetlands also play a role in flood control, acting as natural sponges to absorb rising tides and cleanse stormwater runoff before it reaches Mobile Bay (Ref 1). Additionally, they store stormwater, helping mitigate flooding as storms intensify (Ref 3).
The recreational aspect includes developing nature-based recreation, such as nature trails and kayak launches, as well as expanding public access to natural resources (Ref 3). In 2018, the Perch Creek section was added to the Alabama Coastal Birding Trail, with educational signage for kayakers (Ref 1).
This comprehensive project preserves vital habitats and flood-absorbing wetlands, while providing outdoor recreation opportunities and supporting the coastal community's recovery (Ref 2). It combines high-quality water resources, wildlife connectivity, scenic beauty, and outdoor recreation (Ref 3).