Colin Thorne | |
---|---|
Born | September 1952 (age 71) |
Alma mater | University of East Anglia |
Awards | Back Award (2016) |
Scientific career | |
Institutions | University of Nottingham Queen Mary University of London Colorado State University |
Thesis | Processes of Bank Erosion in River Channels (1978) |
Doctoral advisor | Richard Hey |
Colin Reginald Thorne (born September 1952) is Chair of Physical Geography at the University of Nottingham. [1] A fluvial geomorphologist with an educational background in environmental sciences, civil engineering and physical geography; he has published 9 books and over 120 journal papers and book chapters. [2]
He was educated at Kelvin Hall School and the University of East Anglia (BSc; PhD, 1978). [3] He was awarded the Collingwood Prize by The American Society of Civil Engineers in 1986 [4] and the Back Award of the Royal Geographical Society in 2016. [5]
Colin has been heavily involved in governmental policy including leading the geomorphology work package in the UK's Foresight flood and coastal defence project. [6] He has also sat on the government's SAGE advisory group after the UK Floods. [7] Professor Colin Thorne's research has also had public impact in the Costa Rica vs. Nicaragua International Court of Justice case, where Colin acted as an expert witness. [8]
During a career spanning four decades, has held academic posts at UEA, Colorado State University, the USDA National Sedimentation Laboratory, USACE Waterways Experiment Station, NOAA Fisheries, and the University of Nottingham. He is also a Concurrent Professor at Nanjing University and an Affiliate Professor at Colorado State University. [1]
Thorne led the Blue-Green Cities research project (2013-2016), funded by the Engineering and Physical Sciences Research Council (EPSRC), that aimed to deliver and evaluate the multiple flood risk benefits in Blue-Green Cities. Led by Thorne, the Research Consortium included 8 UK universities: the University of Nottingham, the University of Leeds, the University of Cambridge, Heriot-Watt University, Newcastle University, the University of the West of England, Cranfield University and the London School of Economics as well as partners in the US and China. [9] In June 2013 the Research Consortium selected Newcastle upon Tyne as a Demonstration City [9] partly in response to the June 'Toon Monsoon' in 2012. [10]
A Blue-Green City aims to reconfigure the urban water cycle to resemble a naturally-oriented water cycle [11] while contributing to the amenity of the city by bringing water management and green infrastructure together. [12] [13] This is achieved by combining and protecting the hydrological and ecological values of the urban landscape while providing resilient and adaptive measures to address future changes in climate, land use, water management, and socio-economic activity in the city.
A Blue-Green City is more than the blue and green infrastructure that it comprises; it is a holistic concept that requires collaboration between government, industry and public stakeholders and partnerships working to be fully implemented. [14] Blue-Green Cities generate a multitude of environmental, ecological, socio-cultural and economic benefits through integrated planning and management [15] and may be key to future resilience and sustainability of urban environments and processes. In addition to making the urban environment more resilient to flood and drought events, a Blue-Green City is designed to maximise the use of water as a resource, e.g. through rainwater harvesting, irrigation of river channels, groundwater recharge and as a local amenity. [16] Water is preferentially attenuated and stored on the surface to maximise the potential environmental and social benefits, and reduce stress on the subsurface piped sewer system. A Blue-Green City also aims to collect and store water during flood events for later use in times of drought.
Blue-Green Cities aim to reintroduce the natural water cycle [11] into urban environments and provide effective measures to manage fluvial (river), coastal, and pluvial (urban runoff or surface water) flooding [17] while championing the concept of multi-functional green space and land use to generate multiple benefits for the environment, society, and the economy. [18]
Visible water in cities has massively declined in the last century [19] and many areas are facing future water scarcity in response to changes in climate, land use and population. [20] The concept of Blue-Green Cities involves working with green and blue infrastructure components to secure a sustainable future and generate multiple benefits for the environmental, ecological, social and cultural spheres. This requires a coordinated approach to water resource and green space management from institutional organisations, industry, academia and local communities and neighbourhoods. [21]
The natural water cycle is characterised by high evaporation, a high rate of infiltration, and low surface runoff. [17] This typically occurs in rural areas with abundant permeable surfaces (soils, green space), trees and vegetation, and natural meandering water courses. [22] In contrast, in most urban environments there is more surface runoff, less infiltration and less evaporation. Green and blue spaces are often disconnected. Meaning for a city to be Blue-Green, it requires a further step beyond the implementation of blue and green infrastructure. The lack of infiltration in urban environments may reduce the amount of groundwater, which can have significant implications in some cities that experience drought.[ citation needed ] In urban environments water is quickly transported over the impermeable concrete, spending little time on the surface before being redirected underground into a network of pipes and sewers. However, these conventional systems (‘grey’ infrastructure) may not be sustainable, particularly in light of potential future climate change. They may be highly expensive and lack many of the multiple benefits associated with Blue-Green infrastructure. [23] [24]
Land planning and engineering design approaches in Blue-Green Cities aim to be cost effective, resilient, adaptable, and help mitigate against future climate change, while minimising environmental degradation and improving aesthetic and recreational appeal. Key functions in Blue-Green Cities include protecting natural systems and restoring natural drainage channels, mimicking pre-development hydrology, reducing imperviousness, and increasing infiltration, surface storage and the use of water retentive plants. [25] A key factor is interlinking the blue and green assets to create Blue-Green corridors through the urban environment. [26]
Blue-Green Cities favour the holistic approach and aim for interdisciplinary cooperation in water management, urban design, and landscape planning. Community understanding, interaction and involvement in the evolution of Blue- Green design are actively promoted(e.g. Newcastle's LAA [27] ). Blue-Green Cities typically incorporate sustainable urban drainage systems (SUDS), a term used in the United Kingdom, known as water-sensitive urban design (WSUD) in Australia, and low impact development or best management practice (BMP) in the United States. Green infrastructure is also a term that is used to define many of the infrastructure components for flood risk management in Blue-Green Cities.
Water management components in Blue-Green Cities are part of a wider complex “system of systems” providing vital services for urban communities. The urban water system interacts with other essential infrastructure such as information and telecommunications, energy, transport, health and emergency services. [20] Blue-Green Cities aim to minimise the negative impacts on these systems during times of extreme flood while maximising the positive interactions when the system is in the non-flood state. Key barriers to effective implementation of Blue-Green infrastructure can arise if planning processes and wider urban system design and urban renewal programmes are not fully integrated. [25]
A Blue-Green City actively works with existing grey infrastructure to provide optimal management of the urban water system during a range of flood events; from no flood, to minimal flooding, to extreme rainfall events where the drainage system may be exceeded. [28] Due to these holistic and practical ideals, many infrastructure components and common practices may be employed when planning and developing a Blue-Green City, in line with specific local objectives, e.g. water management, delivery of multi-functional green infrastructure, biodiversity action plans.
The key functions of Blue-Green infrastructure components include water use/reuse, water treatment, detention and infiltration, conveyance, evapotranspiration, local amenity provision, and generation of a range of viable habitats for local ecosystems. In most cases, the components are multi-functional. [12] [29] [30]
Blue-Green infrastructure includes:
A Blue-Green City contains an interconnected network of blue and green infrastructure that work in harmony to generate a range of benefits when the system is in both the flood state and non-flood state. [36] As a concept, Blue-Green Cities accept the need for grey infrastructure in certain scenarios to maximise the benefits accrued. [24] A wide range of environmental, ecological, economic and socio-cultural benefits are directly and indirectly attributed to Blue-Green Cities. Many benefits are realised during times of no flood (green benefits), giving Blue-Green Cities a competitive edge over otherwise comparable, conventional cities. Multi-functional infrastructure is a key to generating the maximum benefits when the system is in the non-flood state. An ecosystem services approach is frequently used to determine the benefits people obtain from the environment and ecosystems. [37] Many of the good and services provided by Blue-Green Cities have economic value, e.g. the production of clean air, water and carbon sequestration. [38] [37]
The benefits include; [39]
The multiple benefits of adopting Blue-Green infrastructure will span both the local/regional and global/international scales. The Department of Environment, Farming and Rural Affairs’ (DEFRA) approach to flood and coastal risk management has been to seek multi-functional benefits from Flood and Coastal Erosion Risk Management (FCERM [44] ) interventions and enhance the clarity of social and environmental consequences in the decision making process. DEFRA note, however, that flood risk reduction benefits provided by ecosystems are not well understood [44] and this is an area where more systematic research is needed such as the SWITCH project.
Work Package 4 of the Blue Green Cities Project involved the creation of a multiple benefit analysis GIS tool box which complements BeST SuDS management tools. [45] The package normalises different Blue-Green benefits so that different scales of benefit can be analysed together thus allowing a quantification of all the potential benefits of new infrastructure. [46]
Concepts of water sensitive cities, such as Blue-Green cities, and tools for water-centric urban design are developing in many countries. [47] For developed cities this may be a case of small changes and building back better with progressive redevelopment. [48] For developing cities the process may be much quicker and circumvent the outdated sewage systems in older cities. [49] Few, if any UK cities have progressed beyond “the drained city“ stage, [50] with water managed for a series of single functions (including flood risk management), mostly through distribution, collection and treatment systems and drainage infrastructure that are energy intensive and which continue to degrade urban environments in general and urban watercourses, in particular. International case studies and the Newcastle demonstration city show the potential of blue green cities in a variety of contexts. The research consortium led by Colin intends to lead a shift in urban developments to reach the potential shown in these case studies.
Newcastle was chosen as a demonstration city for the Blue-Green cities Project due to links with Newcastle University and its Estates, the 2012 flood events and the vulnerability of the city centre to further flash floods. [51] A high percentage of the city centre is impermeable and often unable to cope with high volumes of rain over short periods. A combination of the surface water management plan and community led Learning and Action Alliance [27] was used to select detailed areas to study. These were the middle Ouseburn, Newcastle Great Park and the urban core and adjoining residential area of Wingrove. [52]
SuDS were shown to positively reduce flooding in the Newcastle Great park housing estate [53] and the CityCat flood simulations can be viewed. SuDS were also shown to retain as much as 54% of the suspended sediment that is transported into the ponds, instead of pushing it downstream into the Ouseburn. [54] On top of the ecosystem services benefit to carbon sequestration and habitat size, and reduce air pollution, noise and flood risk the Blue-Green city concept was shown to have successfully created resident approval. [52] 90% of residents’ surveyed (299 total responses) like the SuDS ponds and 61% understand the role of the ponds in reducing flood risk. [55] [56]
Multi-benefit analysis was carried out for Wingrove and Newcastle's urban core using the Multiple benefit tool box created by the research consortium. Evaluation showed that potentially Blue-Green infrastructure in Wingrove would reduce noise and air pollution, increase carbon sequestration and habitat size, and improve access to greenspace for residents. [52] This increase in green space could create a network of blue-green space throughout the city. [46] [57] Showing that despite the impressive improvements already made, there are further potential gains from implementing the Blue-Green city concept in Newcastle.
The Consortium studied the development of the city Portland, to question whether it fit the Blue-Green city concept. [58] It was decided that Portland has advanced into a world-leading Blue Green city through the ‘Grey to Green’ initiative at the turn of the century. [59] This led to a sustainable storm water plan which incorporated Green roofs, tree planting and Green streets. [60] Monitoring reports commissioned suggest that eco-roofs have halved discharge into sewage/stormwater drains. [60] This project was combined with new grey infrastructure in the form of the “Big pipe” project [61] to complement Blue Green infrastructure and ensure it is not overwhelmed by larger events making the city more sustainable in the long run.
On top of the Blue-Green infrastructure, a cultural shift has been integral to Portland's classification as a Blue Green city. This cultural shift is visible in the community led approach to sustainable development and water planning, such as the Foster Green Ecodistrict. [62] To solidify these shifts requires normalisation of Blue-Green techniques being used by design companies, such as Greenworks who carried out the Johnson Creek Oxbow restoration carried out in metropolitan Portland. [63]
Rotterdam is a good example of where the Blue-Green cities process has been initiated with the ideal of climate proofing a city. There has been a repositioning to use water as an opportunity and a resource which has changed perspectives, opening opportunities to manage water better for both flooding and consumption. [64]
A variety of innovative solutions have been used in Rotterdam to maximise water management whilst reducing the impacts of developments, which with traditional hard engineering could be costly both economically and spatially. [65] These include a strong push towards increasing water storage with Green roofs and water squares. [64] The latter of these doubles up as basin storage during flood events. [66] Traditional methods have also been redeveloped towards the blue-green city goal. These include increasing the multi-functionality of dykes, which are needed to reinforce the city against sea level rise, and now have amenities built into their return face. [65] The combination of flood defences, open green space and urban redevelopment have increased the sustainability of this process and opportunities for funding.
The risk of Climate change to a delta city like Rotterdam assisted the cultural shift towards a Blue-Green city with future projects such as Rotterdam weather encouraging grants and public participation in city gardens and more sustainable living practices.
Thorne currently leads the Urban Flood Resilience research project (2016-2020), also funded by the EPSRC. A paper was recently published that presents an overview of the consortium and its research. [67]
Colin Thorne played a part in the creation of the Gravel Bed Rivers Workshop which has been running every 5 years since 1980 and is one of the editors in the first three Gravel-Bed Rivers books written after each of these workshops. [68] [69] [70] The Workshops are designed to present an authoritative review of recent progress in understanding the morphology and processes in gravel bed rivers and each has an accompanying book or special issue journal. [71]
- 1980 Gravel Bed Rivers Workshop 1: "Fluvial Processes, Engineering and Management of gravel bed rivers" United Kingdom [68]
- 1985 Gravel Bed Rivers Workshop 2: "Sediment Transport in gravel bed rivers" Colorado State, US [69]
- 1990 Gravel Bed Rivers Workshop 3: "Dynamics of gravel bed rivers" Florence [70]
- 1995 Gravel Bed Rivers Workshop 4: "Gravel bed Rivers in the environment" Washington State, US [72]
- 2000 Gravel Bed Rivers Workshop 5: "Management goals in gravel-bed rivers" New Zealand [73]
- 2005 Gravel Bed Rivers Workshop 6: "From Process Understanding to River Restoration in gravel bed rivers" Austria [74]
- 2010 Gravel Bed Rivers Workshop 7: "Gravel bed river Processes, tools, and environments" Canada [71]
Keynote speeches for Ice and dams in gravel bed rivers.
- 2015 Gravel Bed Rivers Workshop 8: "Gravel bed rivers and disasters" Japan [75]
The 8th gravel bed river workshop provides some speeches online.
The 9th Gravel Bed River Workshop is set to be on 11 January 2021 in Chile. "Gravel Bed Rivers: Processes, resilience and management in a changing environment" [76]
The main objective of the "FAST Danube" is to "identify the technical solutions to be implemented, in order to ensure navigation conditions on the Romanian-Bulgarian common sector of the Danube". [77] Colin Thorne appraised the likely geomorphic responses to proposed structural interventions by the project and compare these to responses predicted by 2D modelling. [78]
Professor Thorne has been involved in research around the impact of the 1980 Mount St Helens eruption and the long term impact of the associated debris avalanche on the North Fork Toutle River. The eruption dramatically increased sediment yields and led to the creation of a sediment retention structure. [79]
A lot of Thorne's work has focused on how, over time, the system has responded to the complete resetting of the topography and environment. The Alluvial Phase Space Diagram was created to attempt to define how the channel has changed. [80] Moreover, the rate law approach was suggested as a method to understand fluvial response to a major, instantaneous disturbance. [81]
Thorne has been part of a team which suggested a phased sediment management plan to help downstream communities cope with the long lasting impacts which have resulted from the eruption. Where possible this plan only uses dredging as a last resort in order to reduce ecological and economic costs. [82]
The stream evolution model [83] which Thorne co-developed has been applied to the North Fork Toutle in order to classify reaches under the different stream stages set out in the model. [84]
Thorne has led field trips for physical geography students from the University of Nottingham to measure channel responses in the North Fork Toutle River. Part of the practical river restoration and management module. [85]
Thorne was the principal investigator for an analysis of suspended sediment transport data compiled by the US Army Corps of Engineers (USGS). [86]
The final report found that the suspended component of bed material load constitutes only a small percentage of total suspended load, this percentage increased with discharge. Coarse suspended sediment concentrations were also found to have a stronger positive relationship with discharge than fine sediment concentrations. No temporal trends were found when analysing this set of data.
Thorne went on to make 6 recommendations in the final report: [86]
Colin is currently involved in an Inter-disciplinary study to develop a hybrid numerical/rules-based model capable of forecasting future channel changes in the Lower Mississippi River triggered by changes in external drivers and controls of channel form and function. [1] This model is being developed based on the existing HEC-RAS/SIAM [89] and POTAMOD models.
Colin Thorne provide Expert support on geomorphic and sediment aspects of designing intake and control structures through the Mississippi River for the Coastal Protection and Restoration Authority of Louisiana. [90] This project will rebuild, sustain, and maintain land currently subject to erosion in that part of the Mississippi Delta. [91]
Strategic project, on the River Idle, to design river rehabilitation structures to enhance the physical environment and aesthetics of a regulated, channelised lowland river. The project "rehabilitation design was required to tackle these deficiencies through improvements which did not compromise the other obligations of the managing authority." [92]
The project focused on the need for hydraulic modelling to clearly identify restoration techniques would not increase flood risk. The main types of restoration introduced into the study site were flow deflectors to increase hydraulic and sediment heterogeneity, these were then measured using BENDFLOW, HMODEL2, FCFA and HEC-RAS to find the optimum positions and impacts on flow. [92]
A fluvial audit of the Hawkcombe Stream was carried out in 2002. [93] The site was of interest due to flooding in the town of Porlock as a result of sediment dynamics from the proximal upland reaches of the stream. The results of the study have also been presented and are available on the River Restoration Centre website [94]
Colin used the iSIS hydrodynamic model to construct a sediment management plan for the Hawkcombe Stream. He remained a consultant to modify flood defence measures so that they would interact better with sediment dynamics. [95] Colin also helped to develop River Energy Auditing Scheme (REAS) on the Hawkcombe stream which classifies reaches into sediment sources, pathways or sinks in order to understand how sediment dynamics will impact proposed flood management schemes. [96] The understanding of sediment sink reaches was later developed into the stage-0 restoration concept.
Professor Colin Thorne undertook a rapid geomorphological assessment of potential channel instability at points where the Baku Tbilisi Ceyhan (BTC) pipeline crossed river channels. [97]
The Western Route Export Pipeline (WREP) transports crude oil from the Caspian Sea to the Black Sea. [98] Colin provided Rapid geomorphological assessment of potential for channel instability at the two major river crossings in 2010/11. [97]
Colin Thorne led the Sediment Expert Group responsible for reviewing compliance with Mekong River Commission Preliminary Design Guidance on sediment management and potential impacts on sediments, morphology and nutrient balance in the Mekong River that might stem from construction and operation of a main stream dam at Xayaburi in the Lao People's Democratic Republic. [99]
It was recommended that modifications be made to the dam design and operating strategy to avoid or mitigate adverse trans-boundary and cumulative impacts. These recommendations were accepted and acted upon in a $100 million package to allow sediment periodically out of the reservoir. [100]
Colin was part of a collaborative study of present and future flood risks in the Taihu Basin, China involving multidisciplinary work and work packages on hydrology, hydraulics, infrastructure, socio-economics and risk modelling. The UK Foresight Future Flooding approach was used identifying drivers of increased flood risk and ranking them according to their importance in contributing to future flooding. The qualitative [101] and quantitative analyses provided a comprehensive vision of possible future flood risk to inform policy development and decision making. [102]
The project was lead jointly by the Institute of Water Resources and Hydropower Research (IWHR) in Beijing, and the University of Nottingham, UK. The project was funded in the United Kingdom by the Government Office for Science, DEFRA, the Foreign and Commonwealth Office, the United Nations Department for Economic and Social Affairs and the Natural Environment Research Council. [102]
The lessons learnt in applying the UK Flood Foresight approach in to a different context has been shown to have learning opportunities and implications for flood management in the UK. [103] Moreover, a framework was developed for continued long term flooding scenario analysis in China as a result of the project. [104]
A Webpage designated as a Stage Zero information Hub was started By professor Colin Thorne and is available in the external links below along with Stage Zero seminars led by Colin.
Thorne's work on the Stream Evolution Model has led to the application of Stage Zero, otherwise known as "valley floor resetting", as a river restoration condition [83] achievable through a variety of process-based techniques, from 'light-touch' beaver dam analog and post‐assisted logjam methods, to geomorphic gradeline, valley reset methods. [105]
As Stage Zero projects have developed it has become vital that practitioners, scientists and stakeholders should share their perspectives and knowledge in a social learning environment. To facilitate this the Oregon Watershed Enhancement Board and Institute for Natural Resources at Oregon State University convened a Stage Zero stream restoration workshop in November 2020. Brian Cluer provided an introduction to Stage 0 and the Stream Evolution Model that Thorne had worked on. Prof. Colin Thorne attended and moderated panel discussions on ‘The uncertainties and questions regarding restoration to achieve a Stage Zero condition’ and ‘Monitoring approaches and challenges’. Breakout rooms relating to these panel discussions allowed all stakeholders to be contribute. The workshop also held talks on the practises and techniques for creating Stage Zero sites as well as the evolving state of knowledge.
Along with the Upper Deschutes Watershed Council, Thorne has been involved in the Stage Zero restoration of Whychus creek which has created an anastomosing channel in an effort to support increased numbers of anadromous and resident fish, improve stream habitat and expanded biodiversity. [106]
Thorne is the author of the Stream Reconnaissance Handbook [107] which utilises Fluvial Geomorphology
to support accurate classification of the channel, yield reliable pointers to the nature of geomorphic and sedimentary processes, characterize the state of channel stability or instability, and indicate the severity of any instability related problems. [107]
A flood is an overflow of water that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant concern in agriculture, civil engineering and public health. Human changes to the environment often increase the intensity and frequency of flooding. Examples for human changes are land use changes such as deforestation and removal of wetlands, changes in waterway course or flood controls such as with levees. Global environmental issues also influence causes of floods, namely climate change which causes an intensification of the water cycle and sea level rise. For example, climate change makes extreme weather events more frequent and stronger. This leads to more intense floods and increased flood risk.
A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally for a shorter periods. Flooding results in oxygen-poor (anoxic) processes taking place, especially in the soils. Wetlands form a transitional zone between waterbodies and dry lands, and are different from other terrestrial or aquatic ecosystems due to their vegetation's roots having adapted to oxygen-poor waterlogged soils. They are considered among the most biologically diverse of all ecosystems, serving as habitats to a wide range of aquatic and semi-aquatic plants and animals, with often improved water quality by the plants removing excess nutrients such as nitrates and phosphates.
A river delta is a landform shaped like a triangle, created by the deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs at a river mouth, when it enters an ocean, sea, estuary, lake, reservoir, or another river that cannot carry away the supplied sediment. It is so named because its triangle shape resembles the uppercase Greek letter delta, Δ. The size and shape of a delta are controlled by the balance between watershed processes that supply sediment, and receiving basin processes that redistribute, sequester, and export that sediment. The size, geometry, and location of the receiving basin also plays an important role in delta evolution.
Stormwater, also written storm water, is water that originates from precipitation (storm), including heavy rain and meltwater from hail and snow. Stormwater can soak into the soil (infiltrate) and become groundwater, be stored on depressed land surface in ponds and puddles, evaporate back into the atmosphere, or contribute to surface runoff. Most runoff is conveyed directly as surface water to nearby streams, rivers or other large water bodies without treatment.
Climate change adaptation is the process of adjusting to the effects of climate change. These can be both current or expected impacts. Adaptation aims to moderate or avoid harm for people, and is usually done alongside climate change mitigation. It also aims to exploit opportunities. Humans may also intervene to help adjustment for natural systems. There are many adaptation strategies or options. They can help manage impacts and risks to people and nature. The four types of adaptation actions are infrastructural, institutional, behavioural and nature-based options.
Sustainable drainage systems are a collection of water management practices that aim to align modern drainage systems with natural water processes and are part of a larger green infrastructure strategy. SuDS efforts make urban drainage systems more compatible with components of the natural water cycle such as storm surge overflows, soil percolation, and bio-filtration. These efforts hope to mitigate the effect human development has had or may have on the natural water cycle, particularly surface runoff and water pollution trends.
In ecology, urban ecosystems are considered a ecosystem functional group within the intensive land-use biome. They are structurally complex ecosystems with highly heterogeneous and dynamic spatial structure that is created and maintained by humans. They include cities, smaller settlements and industrial areas, that are made up of diverse patch types. Urban ecosystems rely on large subsidies of imported water, nutrients, food and other resources. Compared to other natural and artificial ecosystems human population density is high, and their interaction with the different patch types produces emergent properties and complex feedbacks among ecosystem components.
Green infrastructure or blue-green infrastructure refers to a network that provides the “ingredients” for solving urban and climatic challenges by building with nature. The main components of this approach include stormwater management, climate adaptation, the reduction of heat stress, increasing biodiversity, food production, better air quality, sustainable energy production, clean water, and healthy soils, as well as more anthropocentric functions, such as increased quality of life through recreation and the provision of shade and shelter in and around towns and cities. Green infrastructure also serves to provide an ecological framework for social, economic, and environmental health of the surroundings. More recently scholars and activists have also called for green infrastructure that promotes social inclusion and equity rather than reinforcing pre-existing structures of unequal access to nature-based services.
Stream restoration or river restoration, also sometimes referred to as river reclamation, is work conducted to improve the environmental health of a river or stream, in support of biodiversity, recreation, flood management and/or landscape development.
Urban runoff is surface runoff of rainwater, landscape irrigation, and car washing created by urbanization. Impervious surfaces are constructed during land development. During rain, storms, and other precipitation events, these surfaces, along with rooftops, carry polluted stormwater to storm drains, instead of allowing the water to percolate through soil. This causes lowering of the water table and flooding since the amount of water that remains on the surface is greater. Most municipal storm sewer systems discharge untreated stormwater to streams, rivers, and bays. This excess water can also make its way into people's properties through basement backups and seepage through building wall and floors.
A river is a natural flowing watercourse, usually a freshwater stream, flowing on the Earth's land surface or inside caves towards another waterbody at a lower elevation, such as an ocean, sea, bay, lake, wetland, or another river. In some cases, a river flows into the ground or becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to by names such as creek, brook, and rivulet. There are no official definitions for these various generic terms for a watercourse as applied to geographic features, although in some countries or communities, a stream is customarily referred to by one of these names as determined by its size. Many names for small rivers are specific to geographic location; examples are "run" in some parts of the United States, "burn" in Scotland and Northeast England, and "beck" in Northern England. Sometimes a river is defined as being larger than a creek, but not always; in English the language is vague compared to some languages like French, where a fleuve flows into the sea and a rivière is a tributary of another rivière or fleuve.
Flood control methods are used to reduce or prevent the detrimental effects of flood waters. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and runoff. Flood control methods can be either of the structural type and of the non-structural type. Structural methods hold back floodwaters physically, while non-structural methods do not. Building hard infrastructure to prevent flooding, such as flood walls, is effective at managing flooding. However, best practice within landscape engineering is more and more to rely on soft infrastructure and natural systems, such as marshes and flood plains, for handling the increase in water.
The aim of water security is to make the most of water's benefits for humans and ecosystems. The second aim is to limit the risks of destructive impacts of water to an acceptable level. These risks include for example too much water (flood), too little water or poor quality (polluted) water. People who live with a high level of water security always have access to "an acceptable quantity and quality of water for health, livelihoods and production". For example, access to water, sanitation and hygiene services is one part of water security. Some organizations use the term water security more narrowly for water supply aspects only.
Urban resilience has conventionally been defined as the "measurable ability of any urban system, with its inhabitants, to maintain continuity through all shocks and stresses, while positively adapting and transforming towards sustainability".
Nature-based solutions is the sustainable management and use of natural processes to tackle socio-environmental issues. These issues include for example climate change mitigation and adaptation, water security, and disaster risk reduction. The aim is that resilient ecosystems provide solutions for the benefit of both societies and biodiversity. The 2019 UN Climate Action Summit highlighted nature-based solutions as an effective method to combat climate change. For example, nature-based systems for climate change adaptation can include natural flood management, restoring natural coastal defences, and providing local cooling.
A sponge city is a new urban planning model in China that emphasizes flood management via strengthening green infrastructures instead of purely relying on drainage systems, proposed by Chinese researchers in early 2000 and accepted by the Chinese Communist Party (CCP) and the State Council as nationwide urban construction policy in 2014. The concept of sponge cities is that urban flooding, water shortage, and heat island effect can be alleviated by having more urban parks, gardens, green spaces, wetlands, nature strips, and permeable pavings, which will both improve ecological biodiversity for urban wildlife and reduce flash floods by serving as reservoirs for capturing, retaining, and absorbing excess storm water. Harvested rainwater can be repurposed for irrigation and treated for home use if needed. It is a form of a sustainable drainage system on an urban scale and beyond.
In urban planning and design, blue space comprises areas dominated by surface waterbodies or watercourses. In conjunction with greenspace, it may help in reducing the risks of heat-related illness from high urban temperatures . Substantial urban waterbodies naturally exist as integral features of the geography of many cities because of their historical development, for example the River Thames in London.
Sedimentation enhancing strategies are environmental management projects aiming to restore and facilitate land-building processes in deltas. Sediment availability and deposition are important because deltas naturally subside and therefore need sediment accumulation to maintain their elevation, particularly considering increasing rates of sea-level rise. Sedimentation enhancing strategies aim to increase sedimentation on the delta plain primarily by restoring the exchange of water and sediments between rivers and low-lying delta plains. Sedimentation enhancing strategies can be applied to encourage land elevation gain to offset sea-level rise. Interest in sedimentation enhancing strategies has recently increased due to their ability to raise land elevation, which is important for the long-term sustainability of deltas.
Urban flooding is the inundation of land or property in cities or other built environment, caused by rainfall overwhelming the capacity of drainage systems, such as storm sewers. Urban flooding can happen regardless of whether or not affected communities are located within designated floodplains or near any body of water. It is triggered for example by an overflow of rivers and lakes, flash flooding or snowmelt. During the flood, stormwater or water released from damaged water mains may accumulate on property and in public rights-of-way. It can seep through building walls and floors, or backup into buildings through sewer pipes, cellars, toilets and sinks.
Rainwater management is a series of countermeasures to reduce runoff volume and improve water quality by replicating the natural hydrology and water balance of a site, with consideration of rainwater harvesting, urban flood management and rainwater runoff pollution control.
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