Urban flooding is a complex and distinct kind of flooding, compounded by land use and high population density, and it requires a different approach to assess and manage, says Framing the Challenge of Urban Flooding in the United States, a new report from the National Academies of Sciences, Engineering, and Medicine.

The engineered Dominguez Gap Wetlands in Long Beach filters stormwater and runoff from the Los Angeles River, then the water is siphoned under the river to a spreading ground to the west.; Credit: Sharon McNary/KPCC

Angelenos are used to looking up Heal the Bay's annual beach water quality report card each May as we search out the cleanest places to swim and surf.

Now, the environmental advocacy group is focusing on a new target — the often polluted water that flows into the ocean from the mountains and across the L.A. Basin.

In a first-ever report, it concludes the managers of 12 watersheds from Malibu to Long Beach are making too little progress toward cleaning up this major source of pollution in the Pacific.

This content is from Southern California Public Radio. View the original story at SCPR.org.

Urban planning policy has had a powerful influence on the amount of green space in cities, according to a recent UK study. It found that a change in planning policy in 2000 led to a decline in urban green space in nine cities between 2001 and 2006, although the amount of green space in all but one of the cities studied has increased overall since 1991.

Urban vegetation could have been overlooked as valuable above-ground carbon storage, according to researchers. They estimated that 231,521 tonnes of carbon were stored in above-ground vegetation in a UK city, the majority of which (97 per cent) in trees. This was 10 times the amount estimated from national figures for the same city area.

A new Spanish study has highlighted current developments in the tourism sector that have significant implications for water supply and demand, but are barely addressed in recent land use policies. The findings indicate that any tourist destination that is to follow the ???quality tourist??? model will have an increased water demand in domestic residential areas, which is one of the biggest threats to sustainable water management.

A new study highlights the positive effects of plants and trees in cities. Urban green areas provide shade and reduce temperature fluctuations, bringing average temperatures down, while covering roofs with plants, rather than black roofs, reduces the energy required to heat and cool buildings.

For the first time, researchers have applied a carbon footprint analysis to calculate carbon sequestration by an urban green space. Their results indicate that urban green space can act as a carbon sink, but its design and maintenance influence the amount stored.

A new tool has been developed, with input from the public, to measure and compare the quality of green spaces in urban areas. A UK case study suggests that litter and vandalism are among the factors most likely to prevent local residents from using and benefiting from green spaces.

Heat waves are predicted to become more frequent under climate change, and are likely to be particularly severe in cities and towns due to the Urban Heat Island effect (UHI). A recent UK study of UHI mitigation strategies has demonstrated that even a small urban river can result in a cooling effect of 1??C during temperatures higher than 20??C, and that these cooling effects can be improved by careful urban design of the surrounding areas.

Even small areas of semi-natural vegetation, farmlands and abandoned farmlands provide important ecosystem services in urban environments. However, there is widespread loss of these non-urbanised areas (NUAs) owing to poor planning and urban sprawl. A new five-step process has now been developed that can inform effective planning to protect and enhance the value of urban green spaces.

Researchers in Berlin have demonstrated that urban wasteland areas can be used as suitable habitats for a range of grassland species. Using simple and cost-effective measures to sow grassland seed mixtures, they found that such areas flourished despite poor soil conditions and high levels of impact from people.

The impact of polluted urban soil on trees is highlighted in a recent study from Latvia. The researchers found that high salt levels from de-icing chemicals and nutrient imbalance in soil damaged lime trees growing in the city of Riga.

Green roofs have the potential to significantly reduce road traffic noise in the urban environment, according to a new study. The results suggest that greening of roofs and walls with materials suitable for growing plants softens the urban environment keeping sound levels low, whereas hard, manmade structures tend to amplify traffic noise.

Trees form a valuable part of green infrastructure in cities by helping reduce surface water runoff, recent research finds. Together with grassy areas, significant reductions in surface water flows can be achieved by planting trees, reducing the risk of floods.

Density in the urban environment can encompass a multitude of factors such as population or dwelling density or the density of green areas. A new study surveyed professionals regarding how decisions on urban density are made, and has revealed that many feel that developers make most of these decisions, but that local authority planners should have more influence.

Urban water use increases with a population’s average income, finds a study of a stressed river basin in Spain. Consumption also increases with population age, but falls as education levels rise. Such information could help municipal water providers predict future water trends and to develop appropriate measures by which to manage demand. There is huge interest in mining polymetallic nodules in deep-sea environments. These bumpy rocks on the seafloor contain highly valuable materials including manganese, iron, cobalt, nickel and copper.

While cities worldwide are expanding so is the significant carbon dioxide footprint of urban transport. Consequently, there is an urgent need for sustainable urban mobility solutions. A thorough analysis of the variables and dynamics of urban mobility in cities can aid in planning sustainable mobility policy. This study used a new system of classification by type (typologisation) relevant to urban mobility in global cities, with data from 331 cities in 124 countries covering 40% of the global urban population (as of 2016).

Simply supplying more scientific information on the environment may not be enough to persuade urban planners to give greater consideration to the environment, suggests new research. The Dutch study suggests that environmental values also need to be made more important to municipal decision makers.

Tightly compacted cities can increase flooding risk for local residents, but sprawling, suburban development can lead to major losses in carbon stored by the land and agricultural production. These are the conclusions of a study which explored the effects of different urbanisation patterns on vital ecosystem services.

New research has investigated the combined impact of climate change and land cover change on external household water consumption and local night-time temperatures. It estimates that a 3ºC rise in temperature combined with a high degree of urban sprawl would increase water consumption by 4,061 litres per household for the month of August due to increases in evaporation from ground surface. The study recommends full integration of land use planning and water management.

As society changes, it places new demands on its surroundings. New research has found that some EU countries are better able to manage the undesirable expansion of cities, the concept known as ‘urban sprawl’, because they have a flexible spatial planning policy that can easily adapt to changes. Urban sprawl is a term used to describe the expansion of residential suburbs around city centres, driven by peoples’ desire to live in larger houses and the ease of transport made possible by cars.

Even small areas of semi-natural vegetation, farmlands and abandoned farmlands provide important ecosystem services in urban environments. However, there is widespread loss of these non-urbanised areas (NUAs) owing to poor planning and urban sprawl. A new five-step process has now been developed that can inform effective planning to protect and enhance the value of urban green spaces.

Researchers in Berlin have demonstrated that urban wasteland areas can be used as suitable habitats for a range of grassland species. Using simple and cost-effective measures to sow grassland seed mixtures, they found that such areas flourished despite poor soil conditions and high levels of impact from people.

There is a growing demand for new settlements in and around urban areas due to social, economic and population factors. However, this can lead to the loss of agricultural land and green spaces that provide essential ecosystem services and contribute to the wellbeing of local people. Several countries, such as the UK and Germany, have attempted to limit the growth of urban areas by encouraging the redevelopment of brownfield sites.

The discomfort associated with hot, dry summers in some urban areas can be reduced by planting the most appropriate trees in open city spaces, according to a recent study. The researchers identified the Indian laurel fig as the most effective tree for this purpose in the Greek city of Chania.

Despite the health benefits they bring, the trees and shrubs in our cities can cause health problems for pollen allergy sufferers. Now, a study by Spanish researchers has proposed guidelines for urban planting to reduce the effects of pollen on city-dwellers.

New research has identified 25 variables that influence noise in urban areas. By combining these into an equation, the study produced an accurate tool to describe urban sound environments that could be useful in urban planning.

Noise pollution in urban areas can harm our physical and mental wellbeing, and can have damaging effects on urban wildlife. Now, researchers from China have shown for the first time how a ‘land use regression method’ can be used to model urban noise and predict the effects of future planning decisions on noise levels.

Green roofs have the potential to significantly reduce road traffic noise in the urban environment, according to a new study. The results suggest that greening of roofs and walls with materials suitable for growing plants softens the urban environment keeping sound levels low, whereas hard, manmade structures tend to amplify traffic noise.

Adaptation to climate change in urban regions is a major policy concern. Rather than focus specifically on risk reduction, a new report has reframed the adaptation challenge, giving it a broader focus of increasing an area’s resilience and performance and proposing local-level approaches to leveraging finance for adaptation initiatives.

Urban vegetation could have been overlooked as valuable above-ground carbon storage, according to researchers. They estimated that 231,521 tonnes of carbon were stored in above-ground vegetation in a UK city, the majority of which (97 per cent) in trees. This was 10 times the amount estimated from national figures for the same city area.

Long-term urban planning is needed to adapt the urban environment and make it more resilient to climate change, according to a new European Environment Agency (EEA) report that aims to support urban policy development and decision making.

Climate change is likely to exacerbate the urban heat island (UHI) effect. A new study has therefore examined possible climate change adaptation measures that can alleviate the UHI effect and illustrated how these strategies can be practically applied. While the study provides real-life examples to demonstrate how the measures can be used, it does not include any quantitative assessment of their impacts.

Trees and other vegetation have an important influence on urban temperatures. To explore these effects, Japanese researchers have built and studied scale models of tree-lined streets. This approach could help designers and planners create urban environments that are cooler during summer months.

Green spaces in cities can have a cooling influence which helps reduce the ‘urban heat island effect’. New research from Portugal has demonstrated that even a small community garden can provide a significant cooling impact that can help efforts to adapt to climate change.

Sustainable management of phosphorus requires better information on how it flows through the environment via consumption and waste. New research from Sweden has found that 40% of phosphorus released by Gothenburg to the environment is in sewage sludge and a further 40% is in incineration ash. This suggests that phosphorus could be recycled from solid waste as well as from wastewater.

The urban heat island (UHI) effect can be completely offset by using 'cool' and 'green' roofs, finds new research from the US. However, the study also found that different roofs may affect rainfall and energy demand, and that their efficiency varies with location.

Adding compost to compacted urban soils can provide a lasting effect that aids tree growth, new research indicates. Urban soils improved with added organic material are less compacted after five years compared with soils that have not been treated with organic composts, the study suggests.

Greening urban areas can reduce the number of people dying from heat-related health problems, according to a recent study. The researchers found that doubling vegetation cover in central Melbourne could reduce heat-related mortality of the elderly by up to 28% during heat waves.

The decline of urban populations and abandonment of buildings and land could provide an opportunity to promote ecosystem services, a new study suggests. The researchers examined the relationships between the use of abandoned land and ecosystem services, providing insight into the pros and cons of different urban planning policies.

Doctors prescribe fewer antidepressants in urban areas with more trees on the street, according to recent UK research. The study examined the link between mental health and wellbeing and the presence of trees in London neighbourhoods. Its findings support the idea that maintaining a link to nature, even in an urban area, may help provide a healthy living environment.

Contact with nature in urban areas can have numerous health benefits, a new study finds. The researchers found people whose homes had views of different kinds of vegetation had significantly lower levels of stress hormones, indicating that green spaces play an important role in healthy cities.

A thin layer of lighter coloured asphalt applied to road surfaces could significantly lower surface temperatures in hot urban areas, according to a recent study. This could make living conditions more comfortable and reduce the amount of energy needed to cool buildings.

Cool pavements, which can be used to reduce the Urban Heat Island (UHI) effect, where towns and cities are warmer than surrounding rural areas, have been reviewed in new research. The review found that reflective pavements can reduce temperatures by up to 20°C and are more durable than evaporative pavements, which are less effective at temperature reduction but may have other benefits, such as reducing runoff.

Urbanising arable land can have serious economic consequences as a result of the reduction in food production and loss of ecosystem services, according to recent research. The loss of 15 000 ha of productive soils during 2003-2008 on the Emilia-Romagna Plain in Italy cost approximately €19 million in carbon storage, €100 million in wheat production and €270 million in raw materials, the researchers estimate.

Car use could be reduced through careful urban planning, according to the results of a new German study. By combining data on driving behaviour and high-resolution satellite imagery, the researchers show how patterns of land and car use are connected.

People who live in the most ‘activity-friendly’ neighbourhoods do up to 1.5 hours more physical activity a week than those in the least supportive neighbourhoods. This is according to a new international study which measured levels of exercise — mainly walking for recreation or transport — in relation to the urban environment across 14 diverse cities. The results show how urban design — such as parks and local amenities — can promote healthy lifestyles which also bring environmental benefits, such as better air quality, through reduced car use.

Green Infrastructure (GI), or networks of areas with high ecosystem values, has an increasing presence on the environmental policy agenda. New research has investigated GI policy in urban fringe areas in Northern England and its relationship with the existing green belt policy. The shift towards an 'environmental economy', which values the role of ecosystem services, was found to have helped encourage the uptake of GI.

Ecosystem-based adaptation to climate change relies on the services provided by nature; new research has now demonstrated the wide potential of urban ecosystem services to aid local adaptation efforts. This study developed and trialled a streamlined method for assessing ecosystem services, such as temperature reduction and carbon sequestration, in four European cities, providing a valuable tool to help city planners enhance ecosystem services.

A recent study highlights the role of the public sector in encouraging private investment in natural and cultural brownfield regeneration projects by analysing four models of financing: public-private partnerships, land value finance mechanisms, urban development funds and impact investment funds. Local governments, it is suggested, are well placed to identify and select the most suitable financing mechanisms for redevelopment projects.