Jilin Yanji Low-Carbon Climate-Resilient Healthy City Project (RRP PRC 50322)
CLIMATE RISK AND ADAPTATION OPTIONS ASSESSMENT
Executive Summary
1. Background. The project is located in Yanji city, which faces challenges of poor urban livability and traffic management, exposure to climate-related flood risk, and risks to water security and safety. The project will provide multiple cross-benefits from an integrated solution provided to improve the urban livability of a medium-sized city, which is timely and essential to lessen the migration to the coastal mega-urban regions and to provide a demonstration project for replication in the PRC. It will contribute to (i) regional public goods of health and improved air and water quality, and (ii) revitalizing the economically challenged northeast area of the People’s republic of China (PRC).
2. The project will support the first bus rapid transit (BRT) corridor in the northeast of the PRC and transform Yanji’s urban geography. This will reinforce the east–west linear city arrangement through connecting key areas following principles of transit-oriented development (TOD) with higher density mixed-use and pedestrian-friendly center areas around the BRT stations. It will integrate nonmotorized transport (NMT) lanes and facilities along the corridor, and a series of small roads and river greenways will be provided to ensure safe and pleasant pedestrian and bicycle access to the BRT stations while promoting low-carbon urban mobility and physical activities that enhance public health. The project-supported greenways are designed as “sponge city” green infrastructure, enhancing climate resilience and urban livability.1 The project will improve the water supply and wastewater management systems to ensure safe and climate- resilient access to water supply and improved water quality. Capacity development will contribute to the preparation of action plans to demonstrate Yanji as a low-carbon, climate-resilient, and healthy city, contributing to the implementation of the Healthy China 2030 program,2 and lessons and knowledge will be shared with other developing member countries.
3. Yanji city is part of the Yanbian Korean Autonomous Prefecture in the east of Jilin province, bordering the Democratic People's Republic of Korea to the southeast and the Russian Federation to the northeast. Yanji is an ancient city on the Buer Hatong River surrounded by hills, and its easternmost border is about 15 kilometers (km) from the sea. Yanji’s total population was about 0.60 million in 2018 (about 0.48 million of whom are urban) with about 50.2% being ethnic Koreans, who are well-integrated and live in harmony with the Han Chinese.3 The total land area is 1,748 square kilometers.4 In 2017, the city’s gross domestic product (GDP) was CNY33.6 billion and GDP per capita was CNY61,431. The contributions to the GDP by main sectors in 2017 were agriculture (1.4% of GDP in 2017), manufacturing (36.8%), and services industry (61.8%). Yanji is affected by the regional economic decline of the northeastern PRC, and the city relies mainly on tourism and associated services, processing of agricultural products, and logistics services.
4. Yanji’s climate. The climate of YKAP is characterised by dry and windy spring, warm and wet summer, cool and dry autumn, and long cold winter. Like many parts of northern China, over 60% of the annual precipitation in Yanji happens in the months of June, July, and August. Based
1 Sponge city is a concept of comprehensive urban water resources management, in which greenways, parks, and wetlands maximize ecosystem services, including storm water management, using ecosystem-based adaptation. 2 Government of the PRC, State Council. 2016. The Healthy China 2030. Beijing. 3 Population information of 2018 was collected directly from all the districts, townships, and local communities. 4 Chaoyangchuan township, previously administered by Longjing city, was included under the administration of Yanji in 2008, thus contributing to the rural population increase. 2
on observation data of the Yanji weather station, the extreme minimum and maximum temperature were –32.7°C and 37.7°C respectively, whilst maximum daily rainfall is recorded 105.3mm.
5. Key development challenges. The city suffers from inadequate urban infrastructure and provision of basic services that cause inconvenience and disruptions to daily life, especially for women. This includes inefficient public transport, traffic congestion and poor parking management, urban and river flooding, and inefficient water supply and wastewater management.
6. Project components. This project is to support Yanji city in developing climate resilient and sustainable urban infrastructure. The project includes four components: (i) low-carbon bus rapid transit line integrated with non-motorized transport infrastructure constructed; (ii) climate- resilient flood risk management and sponge city green infrastructure constructed; (iii) water supply system improved; and (iv) capacity in low-carbon, climate-resilient, healthy city planning, and infrastructure management developed.
4. Future climate. The future climate analyses suggest that temperature and precipitation of Yanji city are likely to increase 2°C and 7.9% by 2050, based on the NEX-GDDP downscaled AR5 climate projections. The increased rainfall intensity will also result in increased flood frequency and intensity. Based on hydrological modelling results, the flood discharge rate of Chaoyang River at its confluence with Buer Hatong River will increase 13.5% for floods at 50 years return period. Flood discharge rates will also increase 12–13% for Dongxing Ck, Xinxing Ck, and Guangjin Ck at 20 years return period floods. Moreover, the urban road flooding will be further already deteriorated under further climate change scenarios because of increased rainfall intensity and frequency.
5. Climate risks assessment. Climate risks to project components are all related to either fluvial or pluvial flooding. For component 1, the major climate risk is road flooding at 6–8 sections of the proposed BRT route on Gongyuan and Renmin roads. These sections are currently being flooded several times a year during the rainy season. The situation will worsen under future climate scenarios. Fluvial and pluvial flooding is also the major climate risk to component 2. This includes floods of both Chaoyang River and three creeks in the central urban area that are to be rehabilitated. The catchment area of the three creeks also face serious pluvial urban road flooding risks, due to an inappropriate combined stormwater and sewer pipe system and in some upstream area discharge of untreated domestic water. For component 2 the climate risk is mainly future water availability to ensure safe and secure water supply to Yanji’s water supply system.
6. Hydrological and hydraulic models. In order to assess the climate risks of all project subcomponents, hydrological and hydraulic models have been developed, simulating changes in rainfall runoff, river flows and peak flood flow rates, as well as assessment for drainage pipes north of the Buer-Hatong River. A catchment scale hydrological model has also been developed to support developing adaptation options for Chaoyang River rehabilitation, and assess the future regional water resources. Hydraulic models are also developed to assess the initial technical design in order to develop appropriate adaptation options for the three urban creeks, namely the Guangjin Creek, Xinxing Creek, and Donxing Creek. Those were included in the assessment of impacts from the scenario of adopting low impact development i.e., sponge city green infrastructure that is systemically integrated with improvements that were also suggested fort he drainage pipe network for the catchment areas of the three creeks.
7. Flood risk to component 1. Urban road flooding is the major climate risk to component 1. The roads of the proposed BRT route are currently suffering serious pluvial flooding during the
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rainy season. According to the (incomplete) observation, at least eight road sections being flooded several times a year are located on, or very close to, the proposed BRT route. Project site visits bythe CRA consultants identified more road sections that are subject to flooding caused by heavy rainfalls. Future climate change analysis suggested that the daily maximum rainfall in Yanji is likely to increase 6%, 12%, and 13% for return periods of 1, 10, and 20 years respectively. This will further exacerbate the road flooding risks and make it the biggest challenge in developing adaptation options for this project.
8. River and urban flooding risk to component 2. Fluvial floods are the major climate risks to the integrated rehabilitation of Chaoyang River, which is located in the west end of Yanji city. Heavy rainfall in upstream of the river catchment forced an emergent discharge from the Wudao Reservoir in the middle of the river at 20 years discharge rates. This caused flood water spilling over some points at the river embark in lower Chaoyang River briefly. Based on hydrological modeling under the rcp45 climate change scenario, the peak flood flow in 2050 is likely to increase for 11.35%, 12.28%, 12.93%, 13.50%, and 13.88% for return periods of 5, 10, 20, 50, and 100 years, respectively. This requires also substantial adaptation measures being integrated into the project desgn.
9. The rehabilitation of three creeks in the east side of the city is facing challenges from both fluvial and pluvial flood risks. Stormwater flows to those creeks from both undeveloped upper catchment and buildup areas in the lower catchment. Currently, inappropriate drainage pipelines are also causing urban floods on road sections. Hydrological modeling suggested that under RCP45 scenarios, peak flood flows of those three creeks in 2050 are likely to increase 11-13% for flood event at 20 years return period. This requires adaptation measures for not only the main creek/tunnel but also associated stormwater drainage pipelines.
10. Risk of water shortage to component 3. For component 3, the major climate risk is water shortage for the city’s water supply system at certain dry seasons. For example, water storage in the reservoirs was stressed due to unseasonal drought, and/or consecutive dry years. It is suggested that overall water resource will increase under future climate scenarios as a result of increases in total precipitation. However, there is also likely higher precipitation variability that may exacerbate the dry seasons and dry cycles to cause more serious water shortage to the city’s water supply. Furthermore, the projected population increases, and rising temperature will also raise the city’s water demand significantly. The current water supply system is very inefficient, with which more than half of the total water produced becomes non revenue water. It is very important to raise the water use efficiency of the water supply system to adapt the future climate conditions.
11. Adaptation options assessment and measures developed fort he project. Adaptation options were developd and assessed in various scenarios and in consultation with the various administrative bureaus of Yanji and adaptation measures were developed and integrated in the final technical feasibility study report (FSR) design of the project. The following adaptation measures were developed and proposed by the ADB consultants, and considered and accepted by the local design institute (LDI) and the government. (i) Reshaping of the entire stormwater drainage and sewer network in Yanji’s urban area north of the Buer-Hatong River and along the BRT route with a total investment of about $33 million. This will climate-proof the BRT route protecting it from pluvial flooding in the future and build up the major pipeline network of stormwater management in this northern half of Yanji city and basically eliminate urban flood risk in north of Buer-Hatong River by connecting the nearby stormwater pipes to the major drainage pipes. (ii) A low impact development (sponge city green infrastructure) masterplan was developed by the ADB consultants for the city government including “end-of-pipe/creek” solution to treat the 4 first flush of stormwater. This significant adaptation measure was proposed by ADB and achieved through collaboration among the CRA and TRTA specialists, and engineers of the LDI. This will be demonstrating to the city government an effective measure for tackling future urban flooding in the south side of the city.
12. For component 2, a comprehensive approach is recommended in dealing urban flooding risks for the catchment areas of three smaller creeks. This is to address the urban flooding issue by integrating the sponge city infrastructure in residential complexes with appropriately designed drainage and sewerage pipelines. Storm Water Management Model have been developed for those creeks in evaluate the impact of sponge city infrastructure and the initial FSR design to fine tune these adaptation options. This is probably the first time for ADB projects in PRC adopting such kind of in depth analysis for developing adaptation options. For the Chaoyang River, adaptation options are widening the river embark to enhance the flood protection capacity, together with a 46 ha wetland that can also be a flood diversion plain in the lower reach of Chaoyang River.
13. For the safety water supply in component 3, the major adaptation options are raising water use efficiency in order to adapt the extended drought period caused water shortage to the water supply system. Those include upgrading some old/leaking pipelines and old water meters. This is expected to reduce the NRW from 46% to 37%. This will raise the water supply sustainability by saving 4.81 million m3 water resources annually.
14. Due to the fund availability constraints, some of the recommended adaptation options are put off for future implementation. Those included the opening up Guangjin Creek tunnel and the development of 46 hectares of wetland/flooding plain at lower Chaoyang River. A eco- rehabilitation sketch/plan was also drawn for the West Yuanyi Creek for future government consideration.
15. In addition to those structural proofing/adaptation measures, non-structural adaptation measures are also developed adapting future climate and reducing climate risks Yanji city. Those are included in component 4: (vi) preparation of the Urban Climate Change Adaptation and Sponge City Action Plan including detailed Hydraulic Modeling and Simulation, and (vii) Open Space Masterplan preparation; developing further plans, together with related workshops trainings within component 4.
16. In summary, this is a project with significant investment in climate change mitigation and adaptation. The total climate finance investment for this project is $229.31 million including $82.22 million for mitigation and $147.09 million for adaptation. ADB will finance 46.06% of the mitigation costs ($37.86 million) and 46.06% of adaptation costs ($67.75 million). Details are in the PAM. The total CO2 emission will reduce 60707.82 tons that are mainly contributed by the replacement of diesel buses with clean energy buses and BRT resulted reduction in private vehicle travels.
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A. Relevance
1. Project Background
1.1 Overview
17. The project is located in Yanji city, which faces challenges of poor urban livability and traffic management, exposure to climate-related flood risk, and risks to water security and safety. The project will provide multiple cross-benefits from an integrated solution provided to improve the urban livability of a medium-sized city, which is timely and essential to lessen the migration to the coastal mega-urban regions and to provide a demonstration project for replication in the PRC. It will contribute to (i) regional public goods of health and improved air and water quality, and (ii) revitalizing the economically challenged northeast area of the PRC.
18. The project will support the first BRT corridor in the northeast of the PRC and transform Yanji’s urban geography. This will reinforce the east–west linear city arrangement through connecting key areas following principles of transit-oriented development (TOD) with higher density mixed-use and pedestrian-friendly center areas around the BRT stations. It will integrate nonmotorized transport (NMT) lanes and facilities along the corridor, and a series of small roads and river greenways will be provided to ensure safe and pleasant pedestrian and bicycle access to the BRT stations while promoting low-carbon urban mobility and physical activities that enhance public health. The project-supported greenways are designed as “sponge city” green infrastructure, enhancing climate resilience and urban livability (footnote 1). The project will improve the water supply and wastewater management systems to ensure safe and climate- resilient access to water supply and improved water quality. Capacity development will contribute to the preparation of action plans to demonstrate Yanji as a low-carbon, climate-resilient, and healthy city, contributing to the implementation of the Healthy China 2030 program (footnote 2), and lessons and knowledge will be shared with other developing member countries.
19. Yanji city is part of the Yanbian Korean Autonomous Prefecture in the east of Jilin province, bordering the Democratic People's Republic of Korea to the southeast and the Russian Federation to the northeast. Yanji is an ancient city on the Buer Hatong River surrounded by hills, and its easternmost border is about 15 km from the sea. Yanji’s total population was about 0.60 million in 2018 (about 0.48 million of whom are urban) with about 50.2% being ethnic Koreans, who are well-integrated and live in harmony with the Han Chinese.5 The total land area is 1,748 square kilometers.6 In 2017, the city’s GDP was CNY33.6 billion and GDP per capita was CNY61,431. The contributions to the GDP by main sectors in 2017 were agriculture (1.4% of GDP in 2017), manufacturing (36.8%), and services industry (61.8%). Yanji is affected by the regional economic decline of the northeastern PRC, and the city relies mainly on tourism and associated services, processing of agricultural products, and logistics services.
20. Key development challenges. The city suffers from inadequate urban infrastructure and provision of basic services that cause inconvenience and disruptions to daily life, especially for women. This includes inefficient public transport, traffic congestion and poor parking management, urban and river flooding, and inefficient water supply and wastewater management.
5 Population information of 2018 was collected directly from all the districts, townships, and local communities. 6 Chaoyangchuan township, previously administered by Longjing city, was included under the administration of Yanji in 2008, thus contributing to the rural population increase. 6
21. Urban roads suffer from traffic congestion, especially during rush hours, and missing network links. Many elements of the road network and intersections pose safety problems for vehicles and people. There is a lack of safe bicycle lanes, sidewalks, and pedestrian crossings in many areas. Many cars are parked on sidewalks, creating obstacles for and safety risks to pedestrians. The increase of private cars leads to worsening traffic, increased air pollution and less healthy lifestyles with people walking less. In 2017 there were a total of 152,000 cars in Yanji, which is about 300 vehicles per 1,000 urban residents, and an increase from 96,000 units in 2012. Traffic management and signal control is outdated with suboptimal and unsafe intersections, especially in the congested urban core. The public transport system is inefficient, inconvenient, and unsafe; buses jam in bus stop areas and people get on and off on the streets. Further, there is an urgent need to upgrade and extend public transport into the periphery. Currently, 43 bus routes traverse six roads with a total route length of 490 km and a daily ridership of about 243,000 passengers. The public transport system does not match the needs of a growing population and may cause reduced ridership due to an increase in private vehicle use as people switch modes because of unreliable public transport service and bus shelters that lack weather protection.
22. Flooding is a significant problem during the rainy season in June–July, with flooding for about 5 days per year on average in recent years. River flooding, flash floods, and urban flooding endanger lives, property, and livelihoods, and pose disturbances to traffic and public life. The combined sewer and drainage pipe system is outdated, with a total network length of 326 km, comprising 110 km of sewers, 40 km of drainage pipes, and 176 km of combined sewer and drainage pipes. Only 11.6% of the pipe network meets the domestically required 1-in-3 year flood design standard, causing pluvial flooding during heavy summer rains. The Chaoyang River urban catchment area is currently exposed to flood risks of 1-in-20 year flood events.
23. Yanji city’s water supply system is inefficient. It has two water reservoirs and two water treatment plants with a total combined treatment capacity of 210,000 cubic meters (m3) per day; 150,000 m3/day of treated water meets national water quality standards and is provided as continuous round-the-clock service to end users. The system covers about 98% of the urban area and population with 348 km of water distribution pipes, 91 booster pumps, and around 215,000 water meters. The key challenge is the high level of nonrevenue water (NRW) which was 46% in 2017, comprising 9% in commercial losses and 37% in physical water losses mainly because of aging pipes that were laid in the 1930s and 1970s. It is difficult to detect leaks in deeply buried pipes because of cold climate conditions and incomplete information on pipe locations because of missing and unreliable maps of the old pipe system and poor geographic information system (GIS) management. While the city benefitted from a previous Asian Development Bank (ADB) loan, the above challenges remain.7 Wastewater is collected and treated at two wastewater treatment plants with a combined capacity of 150,000 m3/day. Tariffs for domestic water users are CNY3.20/m3 for water supply and an additional CNY0.95/m3 for wastewater.
7 ADB. People's Republic of China: Jilin Urban Environmental Improvement Project. The project supported water treatment plants, transmission pipes, wastewater treatment plant, and central heating system improvement.
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Figure 1: Location of Jilin Province in north-east China (top) and the basin around Yanji city (bottom).
24. The project will support urban livability of a medium-sized city, contributing to ADB’s strategic support to the PRC’s revitalization and strengthening of the northeast including four cities in East Heilongjiang, north of Yanji.8 Through its strategic and integrated approach, the project will support (i) the thirteenth five-year plans of Jilin province and Yanji city, 2016–2020; (ii) the PRC’s National New-Type Urbanization Plan, 2014–2020, aligning with Yanji’s investment program as one of the PRC’s pilot cities;9 and (iii) Yanji’s urban and economic development master plan (2009–2030) and transport master plan.10 The proposed project is included in ADB’s country operations business plan for the PRC, 2018–2020 and is aligned with ADB’s (i) country partnership strategy for the PRC, 2016–2020, supporting socially inclusive, environmentally sustainable, and economically competitive development; and (ii) ADB’s Strategy 2030 operational priority on livable cities, and support to upper middle-income countries by (a) providing integrated solutions for a livable city demonstrating low-carbon climate-resilient healthy city development generating synergies and cobenefits, contributing to regional public goods, (b) enhancing
8 ADB. People’s Republic of China: Heilongjiang Green Urban and Economic Revitalization Project. 9 Government of the PRC, State Council. 2014. National New-Type Urbanization Plan, 2014–2020. Beijing. 10 Yanji city government. 2009. Yanji City General Urban Master Development Plan (2009–2030). Yanji city.
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resilience to climate change shocks and stresses including reducing flood risk and increasing water safety and security, (c) strengthening institutional knowledge and capacity building, and (d) sharing best practices and innovation experiences for south–south cooperation.11
25. Output 1: Low-carbon bus rapid transit line integrated with nonmotorized transport infrastructure constructed. This output includes (i) planning and constructing a 20-km BRT corridor on Gongyuan Road and Renmin Road in an east–west direction, with about 25 stations, integrated with improved small road links with safe pedestrian and bicycle links to stations and including associated utility pipes, trees, and greening; (ii) procuring a fleet of 100 clean-energy buses and constructing a bus terminal and maintenance center; (iii) installing equipment for smart ticketing and a BRT control center with smart information and communication technology (ICT) monitoring and system-wide, real-time data of bus locations and operation; (iv) removing sidewalk parking, and adding landscaping of public spaces in five locations near BRT stations with installation of exercise equipment; and (v) installing mechanical parking structures for park-and- ride near selected BRT stations and implementing the parking management plan developed under output 4.
26. Output 2: Climate-resilient flood risk management and sponge city green infrastructure constructed. This output includes (i) constructing sponge city green infrastructure in residential areas within the catchment of creeks, integrated with improved and separated drainage pipes (at least 43 km) and wastewater pipes (at least 40 km),12 using results from detailed hydraulic modeling and thereby significantly reducing climate-related pluvial and fluvial flood risks (according to the project’s hydraulic model up to 1-in-50 year flood events), and improving the water quality through construction of sedimentation tanks and reed-bed sand filters at the end of drainage pipes; and (ii) ecological river rehabilitation of the Chaoyang River, improving the flood protection standard from 1-in-20 year floods to 1-in-50 year flood events. Included is bio-engineering as in-stream solutions in the river bed and green embankments, and building pedestrian and bicycle paths with tree planting along this greenway.
27. Output 3: Water supply system improved. This output will improve the water supply system, including (i) installing about 330 flow meters for hydraulic zones and district metering area management, and installing about 4,000 smart water meters in older residential areas; and (ii) upgrading and replacing about 32 km of water supply pipes, including building up hydraulic zones. This follows two already completed phases of an improvement program of the water supply system wholly carried out by the city-owned water group company. This is expected to reduce NRW from the current 46% to 37% during project implementation, conserving about 4.8 million m3 of water resources each year as a result of the project, as part of the water group company’s overall plan to reduce NRW to 20% by 2030. Further NRW reductions will be enabled through a capacity development and utility twinning program under output 4, and proposed further investments may be included in the contract packages of this output as appropriate.
28. and proposed further investments will be included. Under output 2, about 43 km of separate sewer and drainage pipes will be constructed, improving the wastewater and drainage management systems.
11 ADB. 2018. Country Operations Business Plan: People’s Republic of China, 2018–2020. Manila; ADB. 2016. Country Partnership Strategy: People's Republic of China, 2016–2020—Transforming Partnership: People's Republic of China and Asian Development Bank. Manila; and ADB. 2018. Strategy 2030: Achieving a Prosperous, Inclusive, Resilient, and Sustainable Asia and the Pacific. Manila. 12 Civil works contracts under output 1 will integrate construction and installation of drainage and wastewater pipes.
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29. Output 4: Capacity in low-carbon, climate-resilient, healthy city planning, and infrastructure management developed. This output will support project management and quality assurance; external safeguards monitoring; and capacity development for inclusive and gender-sensitive low- carbon, climate-resilient, and healthy city planning and implementation including smart-city ICT application to enhance the sustainability of the project. Activities will include support to and capacity development in (i) project implementation, management, and monitoring; (ii) low-carbon city and TOD planning; traffic impact assessment and evaluation; parking management planning; BRT operation capacity development and network planning; and pedestrian, bicycle system, and universal design masterplan preparation; (iii) urban climate change adaptation and sponge city action planning, open space planning, and hydraulic modelling and simulation; (iv) healthy and age-friendly city master planning and health monitoring, contributing to Healthy China 2030 (footnote 2); (v) water safety planning; NRW reduction and leakage identification and management; and development of an integrated water management system including smart systems using cloud data, supervisory control and data acquisition (SCADA), GIS, and asset management systems as part of smart-city applications; and (vi) GIS platform development and smart-city implementation action planning. Lessons and knowledge will be shared with other developing member countries in the form of guidelines for replication and knowledge-sharing events in Yanji and reports to international and domestic conferences.
1.2 Output 1: Low-carbon bus rapid transit line integrated with nonmotorized transport infrastructure constructed
30. This output will include integrating road rehabilitation, traffic management and road safety, key road links construction, bus rapid transit, bus priority lanes, intermodal bus terminals, new energy buses, improved pedestrian environment, and intelligent transport system applications.
31. The Bus Rapid Transit (BRT Pilot Demonstration Line Gongyuan-Renmin Corridor would be included for ADB financing as the first BRT corridor to be implemented in Yanji. Detailed studies and analysis will be required to define station locations and layout of the corridor and the stations, operational mode, key intersections design, traffic flow organization, traffic impact assessment, pedestrian access to the stations, and other aspects. During the preparation of the project surveys and a data collection program will be carried out under the guidance by the consultants and by the local design institute engaged by the government. The project will aim to improve the traffic capacity of roads and intersections for both buses and mixed traffic.
32. The Gongyuan- Renmin Road corridor is an east-west corridor, north of the Buer Hatong River. The about 20 km Gongyuan-Renmin Road corridor connects two large industrial parks east and west of the urban area with the city center. This corridor has a level of bus ridership and bus demand in both directions in peak hour and off-peak hours that justifies a BRT system. In morning peak current bus volume in that corridor is 84 buses per hour with ridership of 2585 PPHD (passengers per hour per direction) from east to west, 83 buses per hour with 2800 PPHD from west to east. Ridership of 2,800 passengers per hour per direction is higher than in many BRT systems in other cities around the world including in the PRC.
1.3 Output 2: Climate-resilient flood risk management and sponge city green infrastructure constructed
33. This output will include sponge city and climate resilience master planning and investment programming, integrated flood risk management, river rehabilitation, and drainage system improvement that is based on climate risk and vulnerability assessment including hydrological 10
and hydraulic modelling. Green infrastructure will be integrated with existing and new gray infrastructure such as drainage pipes, permeable paving, and retention parks.
34. Flooding, water scarcity, water quality and water safety and security, river ecology and water environment need improved planning and management to increase resilience to climate change. Flooding is a significant problem especially during the rainy season in June and July. River flooding, flash floods and water logging endangers lives, properties and livelihoods, and pose disturbances to traffic and public life. The combined sewer and drainage pipe system is dated, making it difficult to prevent waterlogging and provide adequate drainage during heavy summer rainstorms. Drainage pipes discharge directly into the rivers including the polluted first- flush rainwater.
35. The project aims at improvement of water related climate resilience through integration of flood risk management with ecological river rehabilitation applying a blue-green infrastructure approach. Specifically, the project will include: (i) integrated river rehabilitation and flood risk management at the Chaoyang River west of the industrial park and at the Buer Hatong River along the north bank of the eastern industrial park reducing fluvial and pluvial flood risks meeting national standards, and beyond adapting to climate change responding to climate risk assessment carried out by the consultants. This will be achieved through an ecosystems-based approach creating ecological river environments and enhanced habitats for a great diversity of local flora and fauna and reduce erosion of riverbanks applying bioengineering;(ii) wetland rehabilitation and construction at the Buer Hatong River south of the western industrial park and at the eastern industrial park including storm water detention and habitat functions to increase the biodiversity of flora and fauna (iii) sponge city infrastructure integrating water detention areas i.e. in green parks and sports fields in the urban areas to enhance climate resilience and sustainably reduce flood risk, enhancing the base flow of rivers; (iv) collection and biological treatment of the first flush of stormwater discharged from drainage pipes and combined sewer and drainage overflow; (v) pedestrian and bicycle pathways (and one narrow service road at the eastern industrial park) along ecologically landscaped river green ways to enhance urban livability; and (vi) improve the awareness and build capacity in climate change resilience, flood and water and environment resources planning and management.
1.4 Output 3: Water supply system improved
36. Yanji city is facing challenges in managing its water resources like flooding, drought and water pollution due to rapid urban growth and climate change and there is a need to ensure water safety and security. Increased demand for water require adequate management of water supply and wastewater and drainage, as well as institutional settings. Yanji city has 2 water reservoirs as water resources, the Wudao Reservoir in the upstream of the Chaoyang River and the Yanhe Reservoir in the upstream of the Yanji River. Associated are 2 raw water transmission pipelines, 2 water treatment plants (WTP), 91 water pumping booster stations, 348 km water distribution pipelines, around 215,000 water meters, 1 water quality analysis lab and other auxiliary facilities for water supply. The (NRW) reached 46% of water supply in Yanji city by the end of 2017, including 37% physical water losses. The high NRW cause: (i) low water resources use efficiency posing increasing risks and vulnerabilities to climate change; (ii) high energy cost and water production cost; and (iii) poor water supply service for the local residents, especially during drought periods in the dry season.
37. The objectives of this component are to (i) improve safe, sustainable and quality water supply services infrastructure, and (ii) strengthen the operational efficiency and service quality of
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the Yanji Water Group Co., Ltd. The Water Group has already started two phases of NRW reduction, including upgrading pumping booster stations, replacement of pipeline and water meters. A district metering plan is currently ongoing to identify exact locations of physical water losses which will lead to a detailed NRW loss reduction plan over the course of this year.
38. This component will include upgrade and replacement of about 32 km water supply pipes and 4,000 water meters in the older residential areas and following the first two phases of the improvement of the water supply system. This is expected to reduce the NRW from 46% to 37% and is part of a longer term plan to reduce NRW to 20% by 2030. This component will also include the construction of about 8.7km separate sewer and drainage pipes to improve WWTP management and drainage. Under this component one new sludge treatment plant will be constructed in the Yanji city WWTP with capacity of 150 ton per day to reduce the water content of sludge by 20% and manage harmless final sludge disposal. Plans include the use of the treated sludge as agriculture or forestry fertilizer, depending on the environmental standard of the sludge.
1.5 Output 4: Capacity in low-carbon, climate-resilient, healthy city planning, and infrastructure management developed
39. This output will include institutional capacity development in areas of (a) integrated urban and economic planning including in sustainable tourism; (b) spongecity planning, urban-rural flood risk partnership development and urban climate change adaptation; and (c) sustainable urban transport planning, traffic safety awareness, intelligent transport system, nonmotorized transport, pedestrian and bicycle system, water and wastewater system design and operations, and including smart city systems.
40. This component will: (i) support project management to ensure smooth implementation, and (ii)enable the Yanji city Government and its administrative bureaus to comprehensively plan and implement actions to become a low-carbon and climate-resilient city and serve as a model for the PRC. This component will include a number of distinct capacity development modules relating to the overarching objective of the project of contributing to low-carbon climate-resilient development of Yanji integrating concerned disciplines and involving several concerned administrative bureaus. During the loan implementation a climate resilience strategy and action plan will be prepared. This component will also include capacity development modules that are directly associated with the infrastructure investment components and to improve planning and implementation and operations and maintenance to effectively and efficiently and sustainably deliver urban services.
2. Climate Risk Assessment
41. The approach towards the development of the Climate Risk Assessment (CRA) will be described in this section, while the specific details regarding methodologies and results are presented in the subsequent chapters. Overall, the CRA took the following steps: (i) Analysis of historic climate events (ii) Projections of future climates (iii) Impact and vulnerability of climate change (iv) Adaptation options and recommendations for design
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2.1 Analysis of historic climate events
42. A credible and acceptable Climate Risk Assessment (CRA) starts at analyzing historic observations of climate related events and to perform a trend analysis. Obviously, trends, or the absence of trends, do not imply that future changes will follow those historic trends. Any statistical trend analysis should be accompanied by understanding the underlying physical processes. Analysis of historic climate events should go beyond looking at weather parameters (e.g. temperature and wind) only, but should include parameters that might have been influenced by historic weather conditions. Given the needs of this specific project, the following parameters were analyzed: (i) Precipitation and temperature (ii) Tropical storm frequency and storm surge risk (iii) Flooding (iv) Droughts and water Shortages (v) Land cover changes
2.2 Projections of future climates
43. Projections of future climates are provided by GCMs (Global Circulation Models). The IPCC (Intergovernmental Panel on Climate Change) is the credible body on climate change projections. The IPCC is an intergovernmental body under the auspices of the United Nations “dedicated to the task of providing the world with an objective, scientific view of climate change and its political and economic impacts”. So the IPCC does not carry out its own original research, nor does it do the work of monitoring climate or related phenomena itself. The IPCC bases its assessment on the published literature, which includes peer-reviewed and non-peer-reviewed sources.
44. An important source of the climate projections are the results from the CMIP 5 activities. CMIP5 is the Coupled Model Intercomparison Project Phase 5 that has led to a standard set of model simulation and a more or less uniform output. Since downscaling and local adjustment of GCMs are needed NASA has developed the so-called NEX-GDDP projections (NASA Earth Exchange Global Daily Downscaled Projections). The dataset is provided to assist in conducting studies of climate change impacts at local to regional scales, and to enhance public understanding of possible future global climate patterns at the spatial scale of individual towns, cities, and watersheds.
45. The NASA-NEX-GDDP exists of 21 GCM outputs for two RCPs (4.5 and 8.5) for a historic period and for the future up to 2100. For the CRA the data will be used for two purposes. First, the projections will be analyzed using a set of indicators ranging from more direct ones (e.g. change in temperature) to somewhat more integrated and advanced indicators (e.g. monthly maximum consecutive 5-day precipitation). Second, the NASA-NEX-GDDP will be used for the bottom-up approach of the impact and vulnerability assessment.
2.3 Impact and vulnerability of climate change
46. A standardized approach to climate change impact and vulnerability assessment does not exist. There is however a clear trend in CRAs to move from a climate (GCM) focus to a vulnerability-oriented approach. This change started by the quite often non-consistent projections of GCMs (especially in rainfall) and at the same time the desire to put stakeholders’ perspectives back into the analysis. This distinction between climate scenario driven impact assessment approaches is often referred to as “top-down”, while the vulnerability-oriented approaches is
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referred to as “bottom-up.” The ADB guidelines are less restrictive and recognize that both approaches might work and can be even conducted in parallel:
47. In summary the main difference between the top-down and the bottom-up approach are in the use of GCM projections. The top-down approach is constrained (limited) to the GCM projections, while the bottom-up approach considers a range of potential changes in climate. In this project both approaches were taken in parallel and the focus was the bottom-up approach.
2.4 Adaptation options and recommendations for design
48. Adaptation policy design requires considerations in time-horizon (“when”), spatial (“where”) and decision-level (“how”) terms: there is a need to assess the location of current and future impacts; to identify people, resources, sectors at risk; to gather information about the timeframe of impacts; to define and implement appropriate adaptation actions at appropriate levels of decision-making.
49. ADB has developed some specific guidelines regarding CRAs that have been used as source fort he CRA work: (i) Climate risk management in ADB projects13 (ii) Guidelines for Climate Proofing Investment in the Energy Sector14 (iii) Guidelines for Climate Proofing Investment in the Transport Sector: Road Infrastructure Projects15 (iv) Guidelines for Climate Proofing Investment in the Water Sector: Water Supply and Sanitation.16
50. For the project some initial potential climate adaptation options are outlined. These options are based on a first mission to the project area and analysis as described in this report. Results of the projections as described in this report can be used by the , ADB, ADB consultant team and Local Design Institute (LDI) to adjust their detailed plans and are they have been reflected in the Feasibility Study Report (FSR). A close collaboration between the CRA team and the other teams working on the project led to a specific list of recommendations for adaptation and design.
13 ADB. 2014. Climate Risk Management in ADB Projects. https://www.adb.org/sites/default/files/publication/148796/climate-risk-management-adb-projects.pdf. 14 ADB. 2013. Guidelines for Climate Proofing Investment in the Energy Sector. Manila. 15 ADB. 2011. Guidelines for Climate Proofing Investment in the Transport Sector: Road Infrastructure Projects. Manila. 16 ADB. 2017. Guidelines for Climate Proofing Investment in the Water Sector: Water Supply Sanitation. Manila.
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B. Historic Climate Events
1. Precipitation and temperature
51. An essential step in developing a credible and acceptable Climate Risk Assessment (CRA) is to look at historic observations of climate and to perform trend analyses. Obviously, trends, or the absence of trends, do not imply that future changes will follow the historic patterns. Any statistical trend analysis should be accompanied by understanding the underlying physical processes and future projections using GCMs.
52. Historic records of precipitation and temperature need a rigorous process of data checking, cleaning and gap filling. This process, often referred to as reanalysis, has been developed strongly over the last two decades to support climate change research and analysis.
53. Reanalysis 17 of past weather data provides a clear picture of past weather, independent of the many varieties of instruments used to take measurements over the years. Through a variety of methods and observations from various instruments are added together onto a regularly spaced grid of data. Placing all instrument observations onto a regularly spaced grid makes comparing the actual observations with other gridded datasets easier. In addition to putting observations onto a grid, reanalysis also holds the gridding model constant, keeping the historical record uninfluenced by artificial factors. Reanalysis helps ensure a level playing field for all instruments throughout the historical record.
54. A more technical description of reanalysis is provided by NCAR/UCARs.18 Reanalysis is a systematic approach to produce data sets for climate monitoring and research. Reanalyses are created via an unchanging ("frozen") data assimilation scheme and model(s) which ingest all available observations every 6-12 hours over the period being analyzed. This unchanging framework provides a dynamically consistent estimate of the climate state at each time step. The one component of this framework which does vary are the sources of the raw input data. This is unavoidable due to the ever changing observational network which includes, but is not limited to, radiosonde, satellite, buoy, aircraft and ship reports. Currently, approximately 7-9 million observations are ingested at each time step. Over the duration of each reanalysis product, the changing observation mix can produce artificial variability and spurious trends. Still, the various reanalysis products have proven to be quite useful when used with appropriate care.
55. Some of the key strengths of reanalysis: (i) Data sets, consistent spatial and temporal resolution over 3 or more decades, hundreds of variables available; model resolution and biases have steadily improved (ii) Reanalyses incorporate millions of observations into a stable data assimilation system that would be nearly impossible for an individual to collect and analyse separately, enabling a number of climate processes to be studied (iii) Reanalysis data sets are relatively straightforward to handle from a processing standpoint (although file sizes can be very large)
17 National Centers for Environmental Information. Reanalysis. https://www.ncdc.noaa.gov/data-access/model- data/model-datasets/reanalysis. 18 Climate Data Guide. Atmospheric Reanalysis: Overview & Comparison Tables. https://climatedataguide.ucar.edu/climate-data/atmospheric-reanalysis-overview-comparison-tables.
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56. Some of the key limitations of reanalysis: (i) Observational constraints, and therefore reanalysis reliability, can considerably vary depending on the location, time period, and variable considered (ii) The changing mix of observations, and biases in observations and models, can introduce spurious variability and trends into reanalysis output (iii) Diagnostic variables relating to the hydrological cycle, such as precipitation and evaporation, should be used with extreme caution
57. A couple of reanalysis datasets are available to be used for CRAs. The so-called Princeton reanalysis dataset is regarded as a robust one and often used for climate impact analysis. The Princeton reanalysis product is based on observation and quality control and missing data has been interpolated using advanced statistical analysis.
58. The analysis of historic records of precipitation and temperature is presented below. The most important conclusions that can be drawn are: (i) Long-term annual precipitation in Yanji is 692 mm per year. The rainy season starts in April/May and last till about October. Peak rainy season is July with on average 150 mm per month. (ii) A small increasing trend in annual precipitation over the last 60 years is observed. This trend is about 3 mm increase in 10 years. This trend is very small and not significant and might be cause by some relative wet years over the last 10 years. (iii) Year-to-year variation is quite constant over the period of record, although variation at the end of the last century had the tendency to be somewhat higher. (iv) Daily maximum precipitation in a particular year shows a very significant increase. Overall the daily maximum precipitation in a year is 52 mm/d. However, there is a trend that this has increased by almost 2 mm/d over a period of 10 years. Same trend is observed for the 99% daily maximum. (v) Recurrence time (return period) analysis shows the following numbers: 1:10 years 80 mm/d; 1:50 years 108 mm/d; 1:100 years 120 mm/d. (vi) Temperature: (vii) Long-term annual average mean temperature is 4.1oC. Over the period of records an increase of 0.2 degrees over a 10 years period is observed. The well-known global trend of stabilizing temperatures between 1990 and 2000 is also observed in Yanji. (viii) Analysis of hottest and coldest day in a year shows that for the hottest day no trend occurs. However, coldest day in a year gets “warmer” by 0.7 degrees in 10 years time.
2. Flooding
59. It is important to make a distinction between so-called fluvial and pluvial flooding. The first one originates from high river discharge from upstream, while the latter one is caused by excessive rainfall relative to the drainage (and sponge) capacity of the location considered. Obviously, the origin of fluvial flooding is also by high rainfall events, but in that situation in the upstream catchments. Challenges of river flooding and urban flooding in the project area are significant, especially in the rainy season in summer. It was said that heavy storm events increased over the last years like associated effects of climate change.
60. A typical example was the extreme storm event in Yanji on 20 to 22 July 2017, many people suffered, houses were damaged, and farmland was flooded causing a total loss of more than 74 million RMB (about $10 million equivalent). The event was considered a one in one- 16 hundred-year flood. The upstream reservoirs discharged high volumes of water during the storm adding significant volume at high speeds to flow down the Chaoyang and Yanji Rivers. While in most cases the water levels remained below the dykes, the levels came very close to overflowing and some of the embankments were destroyed. A significant volume of eroded material was transported downstream and settled along the rivers and riverbeds, especially at the constructed dams, weirs and cascades.
61. With an overall precipitation rate of around 700 mm a year, the area can be considered as somewhat drought- and water shortage prone in some of the dryer years. Although evaporation demand in winter time is low, extensive forest areas evaporate a substantial amount of water in spring, summer and autumn. Agriculture also consumes a substantial amount of water in the lower regions of the catchments.
62. The Standardised Precipitation-Evapotranspiration Index is a multiscalar drought index based on climatic data. It can be used for determining the onset, duration and magnitude of drought conditions with respect to normal conditions in a variety of natural and managed systems such as crops, ecosystems, rivers, water resources, etc. It is clear that the southern part of Jilin experiences quite severe drought conditions, while the northern part of the province is relatively wet. To detect trends the SPEI has been analyzed over a longer time period. Interesting is that the last great famine where millions of people lost their lives by starvation in the years 1959-1961, was not one of the driest periods in history. More severe and extended periods of droughts occurred at the end of the 1970’s.
63. A study by Yu et al (2014) investigated the dryness/wetness variation patterns over the entire country based on the same indicator SPEI. Their results can be summarized as follows: (i) A significant upward trend of dry conditions occurred in Northern China, southwestern parts of Northeast China, the central and eastern reaches of ENW China, the central and southwest parts of SW China, and southwest and northeast parts of WNW China; while significant trends towards wetter conditions occurred in eastern parts of the Tibetan plateau. (ii) Comparison of the analysis of trends of annual precipitation and SPEI suggest that these changes are associated with changed in the temperature-based ET component. (iii) Severe and extreme drought areas have increased since the late 1990s by ∼3.72% per decade. In addition, persistent, multiple-year severe droughts have occurred more frequently in N, NE, and WNW during the period1951–2010. (iv) N, WNW, and SW China had their longest drought durations occurring mostly in the 1990sand 2000s. (v) Drought occurrences have become much more frequent in WNW, ENW, N, and NE regions over China during the past 30 years and droughts in the E, SW, and S regions also increased to a lesser degree.
64. The inflow records of the Wudao Reservoir over the last 10 years show a total average inflow over this period is 148 MCM/year (equivalent of about 4.7 cubic meter/second). Although high variation between years can be seen, no trend can be detected given the relative short observation period.
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3. Sponge City
65. The Sponge City initiative in China was launched in 2015 with 16 “model sponge cities”, which has been now extended to many more cities. A Sponge City19 is a city that has the capacity to mainstream urban water management into the urban planning policies and designs. It should have the appropriate planning and legal frameworks and tools in place to implement, maintain and adapt the infrastructure systems to collect, store and treat (excess) rainwater. In addition, a “sponge city” will not only be able to deal with “too much water”, but also reuse rain water to help to mitigate the impacts of “too little” and “too dirty” water.
Figure 2: Pluvial flooding sites.
Source: ADB.
66. Currently, there are 18 pluvial flooding sites in Yanji with 12 in the north of Buer-Hatong River.
67. Many of them are flooded several times every year. The CRA specialists collaborated with the LDI engineers in analysing these sites and found that drainage pipelines are not meeting the standard of 1 year recurrence interval. The ADB consultants inspected those sites, together with experienced staff from the Housing and Urban Construction Bureau and found that: (i) Site 1 - flooded because the natural water course is covered/blocked and water from upstream still flows onto Renmin Road (the BRT route) even in the winter. It flooded the future BRT route on Renmin Road nearly every time there is a fairly substantive rainfall (ii) Site 2 - there is no drainage pipes north of Renmin Road, the stormwater from the build-up areas flows onto Renmin Road along the road when it rains, which floods a long section of the road several times every year; (iii) Site 3 - flooded because one of the drainage pipes that discharges to the Yanji River was blocked by the Water Resource Bureau when they rehabilitated the
19 MDPI. Special Issue “Sponge Cities: Emerging Approaches, Challenges and Opportunities”. https://www.mdpi.com/journal/water/special_issues/Sponge-Cities. 18
Yanji River, and stormwater from Renmin Park then floods the road every time it rains. (iv) Sites 7 and 8 - flooded due to its low altitude, one pump station was built at site 8, which solved that problem and reduced the flood level for site 7. However, flood at site 7 still reaches about 1.2 meters during heavy rainfalls, several times a year. (v) Other sites are also having problems such as the drainage pipes are too small, blocked by sands/silt that floods brought from surrounding hills, and inappropriately constructed pipes etc.
68. Combined sewer and drainage pipes is a key issue causing pluvial flooding. It seems that all pipes are flowing to the eastern edge of the city rather than discharge to the nearby river/creeks. This puts great pressure on the very small pipes and caused bad flooding at sites 7 and 8, and maybe also other sites.
4. Historic climate events: implications for proposed project
69. The first step in the CRA is looking at historic climate events. The main conclusions and implications for the proposed project as described in this chapter can be summarized as follows: (i) Precipitation: Total annual precipitation has been quite constant over the last 60 years and no specific trend is observed. Daily maximum precipitation has increased substantially from average 47 mm/day to 57 mm/day over the last 60 years. The project might therefore be sensitive to increased flooding based on those historic trends. (ii) Temperature: Winters are cold in the project area and during summer temperatures above 30oC are very rare. An increasing trend of temperature increases of 0.2oC per 10 years has been observed. No trend in the hottest day has been seen, while the coldest day in a year has reduced by 0.7oC per 10 years. The project is not sensitive to heat stress and a small positive aspect regarding a decline in cold days can be expected, based on those historic trends. (iii) Tropical storms: No significant trend in tropical storm occurrence has been detected. Specific additional actions regarding tropical storms, beyond normal ones, are therefore not needed for the project, based on those historic trends. (iv) Flooding: Based on available datasets no trend in flooding has been observed. However, specific datasets on local flooding were not available, so a trend analysis on local scale flooding could not be undertaken. Based on historic data on flooding no specific conclusions can be drawn, but the observed increase in wettest day precipitation might lead to additional flood risk and should be considered during project design. (v) Droughts and water shortages: The area receives quite some rainfall and combined with the low evaporation during winter time results in relative low water shortages as long as supply infrastructure is sufficiently developed. Various drought indices and also the observed inflow of Wudao Reservoir show that no trends in water shortages and droughts can be detected. For the proposed project no special adaptation seems therefore needed, based on these historic trends. (vi) Land cover changes: Climate change induced land cover changes were evaluated based on various information sources. No specific trends that might be caused by climate change were detected. However, human influenced changes (e.g. mining) are occurring and risk on erosion and associated adverse impact should be considered by the proposed project.
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C. Projections of Future Climate
1. Methodology
70. The IPCC (Intergovernmental Panel on Climate Change) is the credible body on climate change projections. The IPCC is not involved in undertaking climate change projections by itself, but is an intergovernmental body under the auspices of the United Nations “dedicated to the task of providing the world with an objective, scientific view of climate change and its political and economic impacts”. So the IPCC does not carry out its own original research, nor does it do the work of monitoring climate or related phenomena itself. The IPCC bases its assessment on the published literature, which includes peer-reviewed and non-peer-reviewed sources.
General Circulation Models (GCM) In order to obtain projections of future climates research institutes around the world have developed General Circulation Models (GCMs). GCMs representing physical processes in the atmosphere, ocean, cryosphere and land surface are the most advanced tools currently available for simulating the response of the global climate system to increasing greenhouse gas concentrations. GCMs depict the climate using a three-dimensional grid over the globe (see below), typically having a horizontal resolution of between 250 and 600 km, 10 to 20 vertical layers in the atmosphere and sometimes as many as 30 layers in the oceans. Their resolution is thus quite coarse relative to the scale of exposure units in most impact assessments. Moreover, many physical processes, such as those related to clouds, also occur at smaller scales and cannot be properly modelled. Instead, their known properties must be averaged over the larger scale in a technique known as parameterization. This is one source of uncertainty in GCM- based simulations of future climate. Others relate to the simulation of various feedback mechanisms in models concerning, for example, water vapour and warming, clouds and radiation, ocean circulation and ice and snow albedo. For this reason, GCMs may simulate quite different responses to the same forcing, simply because of the way certain processes and feedbacks are modelled. Source: IPCC
71. GCM data requires substantial efforts in downscaling and local adjustments to make them useable for CRA. Recently, NASA Earth Exchange Global Daily Downscaled Projections (NEX- GDDP) has been developed which is comprised of downscaled climate scenarios for the globe that are derived from the General Circulation Model (GCM) runs conducted under the Coupled Model Intercomparison Project Phase 5 (CMIP5).
72. The NASA-NEX-GDDP dataset includes downscaled projections for RCP 4.5 and RCP 8.5 from the 21 models and scenarios for which daily scenarios were produced and distributed under CMIP5. Each of the climate projections includes daily maximum temperature, minimum temperature, and precipitation for the periods from 1950 through 2100. The spatial resolution of the dataset is 0.25 degrees (equivalent to about 25km by 25km).
73. The approach used to generate the NASA-NEX-GDDP dataset is the Bias-Correction Spatial Disaggregation (BCSD) method. BCSD is a statistical downscaling algorithm specifically developed to address these current limitations of global GCM outputs. The algorithm compares the GCM outputs with corresponding climate observations over a common period and uses information derived from the comparison to adjust future climate projections so that they are (progressively) more consistent with the historical climate records and, presumably, more realistic for the spatial domain of interest. The algorithm also utilizes the spatial detail provided by observationally-derived datasets to interpolate the GCM outputs to higher-resolution grids.
74. The NASA-NEX-GDDP projections are based on 21 GCMs and encompass a historical range (1950-2005) and two future projections (rcp4.5 and rcp 8.5) covering the period 2006-2100. The two rcp projections are transient and in order to make those more transparent three periods were selected: near future (2030), intermediate future (2050) and distant future (2090). These 20 three periods were selected as they represent clear decision-making levels. The near future (2030) is something that will impact current operational practices and if adaptation is needed this will involve current urban and water managers, water users, farmers, citizens etc. Adaptation will be mainly sought in operational and managerial adjustments, and in ongoing project design. The intermediate future (2050) is relevant for investment planning and needed adaptation should focus on those 2050 projections. Finally, the distant future is relevant for strategic planners, policy makers and long-lasting investments (reservoirs, dikes, sea-barriers, soft components such as education, training).
75. Since the projections consider year-to-year variability in precipitation and temperatures the three future scenarios encompass a period of 20 years. So 2030 is the average and variation in climate during the period 2021–2040, 2050 is represented by the years 2041–2060, and for 2090 the years 2080–2099 are being used. Those periods were compared to the reference for which the most recent years of the historic NASA-NEX-GDDP data were used (1986–2005).
NASA-NEX-GDDP The NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) dataset is comprised of downscaled climate scenarios for the globe that are derived from the General Circulation Model (GCM) runs conducted under the Coupled Model Inter comparison Project Phase 5 (CMIP5) and across two of the four greenhouse gas emissions scenarios known as Representative Concentration Pathways (RCPs). The CMIP5 GCM runs were developed in support of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5). The NEX- GDDP dataset includes downscaled projections for RCP 4.5 and RCP 8.5 from the 21 models and scenarios for which daily scenarios were produced and distributed under CMIP5. Each of the climate projections includes daily maximum temperature, minimum temperature, and precipitation for the periods from 1950 through 2100. The spatial resolution of the dataset is 0.25 degrees (~25 km x 25 km). The NEX-GDDP dataset is provided to assist the science community in conducting studies of climate change impacts at local to regional scales, and to enhance public understanding of possible future global climate patterns at the spatial scale of individual towns, cities, and watersheds. Source https://nex.nasa.gov/nex/projects/1356/
Table 1: GCMs Included in the NASA-NEX-GDDP Dataset Model Modelling Center Country Original resolution NASA-NEX resolution Lat Lon Lat Lon ACCESS1-0 BCC Australia 1.25 1.88 0.25 0.25 BCC-CSM1-1 GCESS China 2.79 2.81 0.25 0.25 BNU-ESM NSF-DOE-NCAR China 2.79 2.81 0.25 0.25 CanESM2 LASG-CESS Canada 2.79 2.81 0.25 0.25 CCSM4 NSF-DOE-NCAR USA 0.94 1.25 0.25 0.25 CESM1-BGC NSF-DOE-NCAR USA 0.94 1.25 0.25 0.25 CNRM-CM5 CSIRO-QCCCE France 1.40 1.41 0.25 0.25 CSIRO-MK3-6-0 CCCma Australia 1.87 1.88 0.25 0.25 GFDL-CM3 NOAAGFDL USA 2.00 2.50 0.25 0.25 GFDL-ESM2G NOAAGFDL USA 2.02 2.00 0.25 0.25 GFDL-ESM2M NOAAGFDL USA 2.02 2.50 0.25 0.25 INMCM4 IPSL Russia 1.50 2.00 0.25 0.25 IPSL-CM5A-LR IPSL France 1.89 3.75 0.25 0.25 IPSL-CM5A-MR MIROC France 1.27 2.50 0.25 0.25 MIROC5 MPI-M Japan 1.40 1.41 0.25 0.25 MIROC-ESM MIROC Japan 2.79 2.81 0.25 0.25 MIROC-ESM-CHEM MIROC Japan 2.79 2.81 0.25 0.25 MPI-ESM-LR MPI-M Germany 1.87 1.88 0.25 0.25 MPI-ESM-MR MRI Germany 1.87 1.88 0.25 0.25 MRI-CGCM3 NICAM Japan 1.12 1.13 0.25 0.25
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Model Modelling Center Country Original resolution NASA-NEX resolution Lat Lon Lat Lon NorESM1-M NorESM1-M Norway 1.89 2.50 0.25 0.25 Source: National Aeronautics and Space Administration.
2. Results
76. Results of GCM (General Circulation Model) projections are known to have a broad variation. Since it is unknown which GCM is most accurate and which RCP (Representative Concentration Pathway) is going to happen, the full range of variation should be considered. Only the ACCESS model has been left out, as projections for precipitation of this model were physically impossible (e.g. daily precipitations above 500 mm).
77. The combination of 21 GCMs and two RCPs and three time horizons brings a total of 126 (21*2*3) projections for the future. By plotting the projected changes in temperature and the projected changes in precipitation a clear picture of potential futures can be seen. Projected increase in temperature are somewhere between 0oC and 8oC, while projected precipitation changes are from about 10% dryer conditions to even over 100% (more than doubling!) precipitation amounts. It should be noted that in principle this entire range is plausible as all projections are based on rigorous scientific knowledge. Obviously, the outliers might be somewhat less likely than the more clustered projections. In summary it might be claimed that the projected changes in are between -10% and +50% in precipitation and 1 oC to 8oC warmer.
78. The main conclusions from a more detailed look into the individual 21 GCMs and time horizons are that quite some constancy exists in terms of future projections, although some exceptions/outliers can be seen. The ACCESS GCM is an exception for the projected precipitation under RCP8.5; much higher precipitation compared to the other GCMs. Also, CANESM2, GFDL- CM3 and MIROC5 project a quite wetter future. Regarding temperature more consistency can be observed with clear trends of higher temperatures in the more distant future, and under RCP85 larger increases compared to the RCP45.
Table 2: Summary of Climate Change Impact on Changes in Annual Temperatures Average (oC) GCMs >2oC GCMs >4oC GCMs >6oC 2030_rcp45 1.3 3 0 0 2050_rcp45 2.0 9 0 0 2090_rcp45 2.8 16 3 0 2030_rcp85 1.5 4 0 0 2050_rcp85 2.7 17 3 0 2090_rcp85 5.5 21 19 7 Source: Asian Development Bank.
Table 3: Summary of Climate Change Impact on Changes in Annual Precipitation Average (%) GCMs Dryer GCMs Wetter 2030_rcp45 +5.2 4 17 2050_rcp45 +7.9 3 18 2090_rcp45 +9.8 3 18 2030_rcp85 +7.9 3 18 2050_rcp85 +11.8 2 19 2090_rcp85 +20.8 2 19 Source: Asian Development Bank.
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Table 4: Summary of Climate Change Impact on Changes in Return Periods (1, 10 and 20 year) in Daily Precipitation Changes in daily maximum precipitation 1 year 10 years 20 years 2030_rcp45 +3% +7% +7% 2050_rcp45 +6% +12% +13% 2090_rcp45 +14% +12% +12% 2030_rcp85 +4% +6% +6% 2050_rcp85 +12% +13% +13% 2090_rcp85 +27% +18% +17% Source: Asian Development Bank.
79. Figure 3 indicates the most likely changes for the three time horizons in terms of changes in precipitation and changes in temperature. Since the proposed project will include investment components that will last for the coming 50 years (e.g., BRT) and components that will last longer (sponge city and catchment planning) it is advisable to take the full range of planning horizons.
Figure 3: Projected changes in precipitation and temperature for Yanji city. 9 8 2030 7 2050 6 2090 5 4 3 2 1 Temperature Change (oC)Change Temperature 0 -20 -10 0 10 20 30 40 50 Precipitation Change (%)
3. Projections of future climate: implications for proposed project
80. The second step in the CRA (Climate Risk Assessment) is looking at projections of future climates using GCMs (General Climate Models). The main conclusions and implications for the proposed project as described in this Chapter can be summarized as: (i) Precipitation: Annual total precipitation is projected, according to the GCMs, to increase slightly. Daily maximum precipitation is also projected to increase under all RCPs and all future horizons. The project might therefore have sensitivity to increased flood risk based on those projections. (ii) Temperature: Temperature is projected to increase between of 1oC (near future, RCP 4.5) and 8oC (distant future RC 8.5). Since the project is located in a cold region no severe heat stress is expected. Higher temperatures and a prolonged growing season will lead to higher evaporation demands for natural as well as agricultural vegetation.
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D. Impact and Vulnerability of Climate Change
1. Methodology
1.1 Methodology
81. There is no standardized methodology to look at future impacts of climate change that can be applied universally. Main reason is that each project has its specific focus and potential risks that requires different levels of detail, focus and approaches. Moreover, CRA studies are relatively new and standardization needs time to evolve based on past experiences.
82. Originally the name Climate Risk and Vulnerability Assessment (CRVA) was used. However, since vulnerability is part of risk, it is recommended to use the term CRA. A couple of CRA methodologies/frameworks have been developed over the last decade and will be summarized here. Definitions used in CRAs are sometime confusing and it is proposed to use the following more or less accepted ones: 20 (i) Exposure: The presence of people, livelihoods, species or ecosystems, environmental functions, services, and resources, infrastructure, or economic, social, or cultural assets in places and settings that could be adversely affected. (ii) Sensitivity: The degree to which a system, asset, or species may be affected, either adversely or beneficially, when exposed to climate change and variability. (iii) Potential impact: The potential effects of hazards on human or natural assets and systems. These potential effects, which are determined by both exposure and sensitivity, may be beneficial or harmful. (iv) Adaptive capacity: The ability of systems, institutions, humans, and other organisms to adjust to potential damage, to take advantage of opportunities, or to respond to consequences of hazards. (v) Vulnerability: The extent to which a system is susceptible to, or unable to cope with, adverse effects of climate change, including climate variability and extremes. It depends not only on a system’s sensitivity but also on its adaptive capacity. (vi) Likelihood: A general concept relating to the chance of an event occurring. Generally expressed as a probability of frequency. (vii) Risk: A combination of the chance or probability of an event occurring, and the impact or consequence associated with that event.
83. ADB has developed specific guidelines regarding CRAs. Some typical examples include: (i) Climate risk management in ADB projects (footnote 7) (ii) Guidelines for Climate Proofing Investment in the Energy Sector (footnote 8) (iii) Guidelines for Climate Proofing Investment in the Transport Sector: Road Infrastructure Projects (footnote 9) (iv) Guidelines for Climate Proofing Investment in the Water Sector: Water Supply and Sanitation (footnote 9).
84. These guidelines mentioned that the main characteristics of a CRA are: (i) To characterize climate risks to a project by identifying both the nature and likely magnitude of climate change impacts on the project, and the specific features of the project that make it vulnerable to these impacts.
20 Definitions adapted from IPCC, Climate Change 2014: Impacts, Adaptation, and Vulnerability, Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (2014); UKCIP. http://www.ukcip.org.uk. 24
(ii) to identify the underlying causes of a system’s vulnerability to climate change (iii) the CRA process embodies the recognition that many of the future impacts of climate change are fundamentally uncertain and that project risk management procedures must be robust to a range of uncertainty (iv) To ensure that adaptation measures are locally beneficial, sustainable, and economically efficient.
85. According to the ADB guidelines a CRA follows a series of steps (note that Step 1-5 are the so-called climate screening steps): (i) Step 6: Identify Vulnerability of Project Components (ii) Step 7: Identify Biophysical Drivers of Vulnerability (iii) Step 8: Identify Socioeconomic Drivers of Vulnerability (iv) Step 9: Develop Appropriate Climate Change Scenarios (v) Step 10: Estimate Future Biophysical Impacts (vi) Step 11: Assess Impacts on Investment Projects
86. Many recent studies make a distinction between climate scenario driven impact assessment approaches, often referred to as “top-down” and vulnerability-oriented approaches, often called “bottom-up.” The ADB guidelines are less restrictive and recognize that both approaches might work and can be even conducted in parallel.
87. While current good practice in adaptation emphasizes risk management, and increasing recognition of the fundamental uncertainty of future climate discourages the over interpretation of model generated climate projections, impact and vulnerability assessments should be understood as complementary processes in project climate risk management, and they can be conducted in parallel: (i) An impact assessment is useful in narrowing and illuminating the potential range of future conditions with which project designers must be concerned. (ii) A vulnerability assessment provides an understanding of how robust the project and specific project components are to departures from design assumptions and identifies critical thresholds of vulnerability past which the project fails to perform as designed.
88. In summary the main difference between the top-down and the bottom-up approach are in the use of GCM projections. The top-down approach is constraint (limited) to the GCM projections, while the bottom-up approach considers a range of potential changes in climate.
2. Impact Models
89. Two hydrology and hydraulic models are used in this study to assess the climate change impact/risks and develop appropriate adaptation measures. Water Evaluation and Planning" system (WEAP) model is selected for modelling the river flows and fluvial flood risks. Storm Water Management Model (SWMM) is selected to model the hydrology/hydraulic of the stormwater drainage systems for north Yanji City, including the three smaller creeks to be rehabilitated.
2.1 WEAP Model
90. WEAP is a modelling software that operates on the basic principle of a water balance and can be applied to municipal and agricultural systems, a single watershed or complex transboundary river basin systems. It is selected in this study for catchment impact assessment
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to address the fluvial flood risks, principally the Chaoyang River and three other smaller creeks, including Guangjin Creek, Xinxing Creek, and Dongxing Creek.
91. There are various reasons for choosing the WEAP framework as the most relevant one to be used for CRAs. Most important is that WEAP is completely focused towards scenario analysis in a user-friendly approach. Second, WEAP is very scalable and a first-order setup of a particular region can be easily expanded when more data/resources are available. Third, WEAP is commonly used world-wide for IWRM analyses. Finally, WEAP is freely available for organizations in developing countries.
92. Availability and access to good quality of data is essential for IWRM analysis using WEAP. Required input data can be divided into the following main categories: (i) Model building (a) Static data21 1. Digital Elevation Model 2. Soils 3. Land use, land cover 4. Population 5. Reservoir operational rules (b) Dynamic data 1. Climate (rainfall, temperature, reference evapotranspiration) 2. Evapotranspiration by crops and natural vegetation 3. Water demands by all sectors 4. Reservoir releases (ii) Model validation/calibration (c) Stream flow
93. The WEAP framework is flexible in level of details of data availability. A typical example is that water demands can be included as a total amount of water, but can be also estimated by WEAP using population, their daily required intake and daily and/or monthly variation. Similarly, climate data can be entered at annual, monthly, 10-days or daily level. The more refined the input dataset is, the higher the reliable of the WEAP model scenarios will be.
94. The WEAP impact model is capable of capturing all the components of the water balance and water resources. Water availability, flooding, drainage, water demand, water distribution, water shortages, sediment load and hydro power are some of the most relevant features. To access water resources (including water shortages and water surpluses) WEAP includes a catchment approach that requires delineation of a study area into sub-catchments. Based on the SRTM-DEM this catchments delineation has been done. A total of 15 catchments has been defined, where each catchment has been subdivided by various land-use classes. Other characteristics, such as elevation, slope, and soil types are specified as well.
95. The river network was added to the model based on the DEM delineation and available maps. The two main reservoirs, Wudao on Chaoyang River and the Yanhe on Yanji River, were added to the model as well. Domestic and industrial water demand were added as well to the model.
21 Note that static data can still vary over longer time frames, but are fairly constant over days/weeks 26
96. Climate data was obtained by combining local data and the Princeton data set as described before. Climate projections for the future were extracted from the NASA-NEX-GDDP as analyzed in Chapter 3.
97. The entire model setup including all those components can be seen in Figure 4.
Figure 4: Screenshot of impact model WEAP for entire basin: model schematization
2.2 SWMM model
98. Whilst the WEAP model simulated the large river/catchment flood risks, it is not capable of modelling the pluvial flood risks in urban areas the involved the stormwater drainage system. In this study, we shall use PCSWMM model to carry out climate risk assessment to the current stormwater drainage system and FSR designs for proposed project subcomponent, evaluating sponge city infrastructure and other adaptation options.
99. PCSWMM is developed based on USEPA SWMM model but with many added functions to enable much easier modelling with EPA SWMM. It is capable of supporting the improvement of new water supply, drainage and green infrastructure design, floodplain delineation, sewer overflow mitigation, water quality and integrated catchment analysis, 1D-2D modelling – and much, much more.
100. Figure 5 shows the SWMM concept model. It is a distributed, dynamic rainfall-runoff simulation model used for single event or long-term (continuous) simulation of runoff quantity and quality from primarily urban areas. It has also hydraulic modelling features to Handle drainage networks, various conduit shapes as well as irregular natural channels, pumps, regulators and storage units, external inflows from runoff, groundwater, RDII, sanitary, DWF, and user-supplied time series, and using flexible rule-based controls for pumps and regulators It can be used to model various flow regimes, such as backwater, surcharging, reverse flow, and surface ponding.
101. SWMM models in this study are set up with the existing drainage network in north Yanji to assess the flood risks of BRT route, and the initial FSR designed pipelines for the three smaller creeks to assess their flood risks. This formed different SWMM models (Figure 5) have been developed using PCSWMM. Those are:
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(i) North Yanji city model. The objective of this model is to assess climate risks of the existing drainage pipelines of north Yanji city where pipeline data is available for areas in the north of Buer-Hatong River, in order to identify possible solutions and/or adaptation measures to reduce urban road flooding. (ii) Guangjin Creek model. Guangjin Creek is representing one of the many natural drainage basins but its drainage channels were modified during the urbanization process. It is proposed to rehabilitate the drainage system of this creek with new stormwater pipelines and sponge city infrastructure in selected residential complexes. The model will assess climate risks of the FSR design and evaluate the impact of the proposed sponge city infrastructure, and identify other adaptation options. (iii) Xinxing Creek model. Xinxing creek is an natural drainage basin that is fully urbanized with densely built residential complexes now. The model will assess climate risks of the FSR designed drainage network. (iv) Dongxing Creek model. Dongxing creek is the least urbanized natural drainage basin compared with the two others. Most of its upstream catchment are still in its natural form except some villages. Only the lower catchment are urbanized now. The model will assess FSR designed drainage network as well as evaluate the impact of sponge city infrastructure in selected complexes.
Figure 5: SWMM model concept
Source: Colorado state university
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Figure 6: Four SWMM model areas in north Yanji (The Dongxing Creek model areas include natural/rural areas and urbanised areas, which are shown in different colours)
Source: ADB
3. Climate change impact
3.1 Introduction
102. The impact of climate change following the bottom-up approach as explained in the previous sections,starts with looking at sensitivity of climate parameter on various indicators. The following indicators were selected: (i) Streamflow of Buer-Hatong at entry point in Yanji city (ii) Streamflow of Yanji river into Buer-Hatong river (iii) Inflow into the reservoirs Wudao and Yanhe (iv) Reservoir levels Wudao and Yanhe (v) Flooding in Yanji
3.2 Streamflow
103. Based on the WEAP model as presented in the previous sections, a period of 20 years (1991-2010) daily flow has been simulated using the prevailing climate conditions. Average annual outflow is 1.12 m3s-1Table 5. By stepwise increasing the temperatures from 1 to 8 degrees Celsius the model has run again and expected flows are presented in the same table. Average flow in the reference situation are 1.12 m3s-1 and by increasing temperatures those flows can be expected to reduce to values as low as0.34 m3s-1. The physical explanation for this is that by increasing temperatures more water will be evaporated and consumed so less water will end up in the river.
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104. For precipitation the same approach has been followed. Considering the projected changes by the various GCMs (previous sections) changes in precipitation ranges from 20% less rainfall to 60% increase. The resulting projected flows, based on the WEPA impact model, are shown in Table 5 as well. Interesting is that a reduction of 20% in rainfall will reduce streamflow by about 50%. Similar, 40% more rainfall will result in more than 100% additional streamflow. This phenomenon is well known in hydrology and is caused by the highly non-linear behavior of the hydrological cycle.
Table 5: Impact of changes in precipitation (dP) and temperature (dT) on outflow of Yanji river into Buer-Hatong River as average annual flow 1991-2010 dT (oC) (m3/s) dP (%) (m3/s) 0 1.12 80% 0.52 2 0.91 100% 1.12 4 0.70 120% 1.91 6 0.50 140% 2.81 8 0.34 160% 4.82
105. The results of the WEAP impact model were also used to construct a similar climate response figure for Buer-Hatong River at the point where it enters Yanji city. Instead of looking at actual flows the changes in flows compared to the reference situation were considered. It is clear that under combined changes in temperature and precipitation, flows will reduce to only about 20% of the reference situation (dT=8 and dP = 80%) up to 270% (dT = 0 and dP = 160%). Again, the GCM projections are plotted as dots and a kind of window of expected flows shows that changes between 50% and150% can be expected. A more likely scenario (dT between 1 and 3oC; dP between 90 and 120%), considering the clustering of GCMS, is that the range in expected changes in flows is no changes to an increase of about 20% compared to the refence situation.
3.3 Floods
106. Flooding has been occurred in the past in the project area. Although the severity of the flooding has been modest so far, every single flood event has substantial impact. The July 2017 flood resulted in many people suffering and damaged houses, and economic losses were estimated at around $10 million. It was said that this event can be considered as a one in one- hundred-year flood.
107. Using the WEAP impact model flood risk and severity under changing temperature and precipitation has been evaluated. Important is to make a distinction between the cause of the flood whether being dominantly fluvial (from high river flows) or pluvial (local intensive rainfall). In general, fluviatile flood risk can be considered as modest for Yanji city. Interesting is that increasing temperatures will reduce flood risk quite substantially. Higher evaporation and dryer soils leads to higher buffer capacity in the upper catchment. When the increase in precipitation by climate change will be above 40%, fluviatile flooding will become a threat to Yanji city. However, considering the limited number of GCMs projecting such a big change in precipitation, an extreme increase in flooding is not expected.
108. The area most prone for flooding is assessed using a digital elevation model (DEM). The DEM used is of intermediate resolution and therefore three refinements has been made to the original DEM to ensure that the DEM can be used for flooding area assessment. The original DEM has been resampled by a factor 9 using splined interpolation, the river itself has been overlaid to have a more accurate representation of the actual situation, and the DEM has been de-trended to make it suitable for flood area estimation. The north-eastern part of the city, just north of the 30 river is most vulnerable for floods. The expected flooding depth with this 10 million m3 goes for some of those areas to 2 meters. A flooding of 50 million m3 would affect also the western part just at the edge of the city and some areas along the Yanji River.
3.4 Water availability
109. The proposed project includes also water supply components and therefore the impact of climate change on low flows is relevant. For this, the 5% lowest daily flow in a year has been used as indicator. The WEAP impact model was run multiple times for changes in temperature and precipitation. Higher temperature will induce higher evaporation rates and increased water consumption, while changes in precipitation will affect runoff. Considering the most likely future climate projections based on the climate projections those low flows will be somewhere between 80% and 120% compared to the reference situation.
3.5 Urban pluvial flooding assessment
110. The assessment results for north Yanji shows wide-spread flooding on roads and residential complexes when modelled with an one year return period rainfall event. This is consistent with observations of local government officers who claimed that many roads are flooded several times a year. With projected increases in severe rainfall events, it is very important to develop appropriate adaptation measures for the BRT route and other roads.
111. The Guangjin Creek model is based on the FSR designed stormwater pipelines because there is not current pipeline data available. A rainfall event at three years return period is used to run the model, which is the design standard used by the LDI. Whilst most of the pipelines are sufficient, there is one manhole being flooded significantly, which also caused large flooding areas along the Guangjin Road.
112. The FSR designs for both Xinxing and Dongxing Creeks are meet the design standard of 3 years return period rainfall events. However, there are still flood risks for both creeks because the design standard is very low, although they meet the PRC government guidelines. Therefore, some adaptation measures are still required.
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E. Climate Risk Assessment for Project Subcomponents
113. In this project, climate risks to project subcomponents are all related to either fluvial or pluvial flooding. Component 1 is considered as a major mitigation activity that will promote public transport and reducing GHG emission. However, a number of sites along the BRT route are subject to frequent floods during the rainy season, which are often flooded several times every year. Based on observation, there are a number of sites on proposed BRT route subject to flooding during the rainy season.
114. Component 2 is aimed to develop sponge city green infrastructure to connect to the grey urban infrastructure to address existing flood risk issues. The ecological rehabilitation of Chaoyang River is mainly to address the fluvial flood risks. Whilst the rehabilitation of three smaller creeks, Dongxing, XInxing, and Guangjin creeks, are to address both fluvial and pluvial risks as stormwater from both upstream catchment and surrounding build up areas flowing through those creeks.
115. This chapter outlines some initial potential climate adaptation options. This assessment is based on a first mission to the project area and analysis as described in the previous sections. Results of the projections as described in this report can be used by the PPTA team and Design Institute (DI) to adjust their detailed plans and are reflected in the Feasibility Study Report (FSR).
1. Climate risks assessment for Component 1 - Low-carbon urban mobility with sustainable integration of multiple traffic modes promoting transit- oriented urban development
116. This component is to build infrastructure to promote public transport, Nonmotorized Transport (NMT), and improved traffic management and safety. This component includes subcomponents: (i) Bus Rapid Transit Pilot Demonstration Line (BRT) that connects two large industrial parks east and west of the urban area with the city center; (ii) Sustainable Integration of BRT with NMT and Other Traffic Modes and Land Use Planning; (iii) Improvement of the NMT Network and Pedestrian Environment; (iv) Intermodal Bus Terminals; (v) Traffic Management, Road Safety and Intelligent Transport System.
117. This component is considered as a substantial mitigation activity that improves and promotes public transport and nonmotorized transport for people of Yanji city. However, there are also significant climate risks to the proposed BRT route and associated BRT facilities. Many road sections on the proposed BRT route are currently suffering serious pluvial flooding during the rainy season. There are eight observed flooding sites either on or very close to the proposed BRT route. Project site visits identified that there is another site on the proposed BRT route suffering serious flood problem. According to future climate change analysis (Table 4), the daily maximum rainfall in Yanji is projected to increase 6%, 12%, and 13% for return periods of 1, 10, and 20 years respectively. This will further exacerbate the road flooding risks and make it the biggest climate risk for this project.
118. In this study, we have developed a Storm Water Management Model (SWMM) model to assess climate/flood risks to the proposed BRT route. The SWMM model simulated the rainfall- runoff, together with existing stormwater drainage pipelines of north Yanji city, using maximum daily rainfalls for 1, 2, and 5 return periods. Figure7 shows the wide-spread flooding on both 32 roads and residential complexes in north Yanji that are modelled with a rainfall event of 37.2 mm within 12 hours (one year return period event). This result is consistent with the assessment of Yanji city Stormwater Water Drainage and Flood Protection Plan (2016).
Figure 7: Modelled area with flooding risk in north Yanji with one year's rainfall event
119. Under the future climate scenarios, the daily maximum rainfall is likely to increase 6% for one year return period (Table 4). This will be 39.4mm/24hr in 2050 under RCP45 scenario. The SWMM modeling results for north Yanji city in 2050 under RCP45 scenario with daily rainfall at one year return period show that of the total 242 junctions in the model, 116 junctions will be flooded for 0.75 – 23.99 hours during the day. There are also more than 70 of the 243 conduit sections are above normal full for 2 – 22.5 hours during the event.
120. Based on both government observation and modeling results, the proposed BRT will face significant changelings in both current and future climate conditions. Urban flooding is a common but difficult issue to deal with in many cities of PRC. The urban areas have been expanded significantly in the last couple of decades, but drainage network was largely not updated with the fast urban development. Therefore, many urban areas, especially the old urban areas are often facing serious road flooding problem. Therefore, substantial adaptation measures are required for successful implementation of the BRT component for sustainable low-carbon public transport.
2. Climate risks assessment for Component 2 - Climate-resilient ecosystem- based flood risk management and sponge city infrastructure
121. Flood risks in Yanji include both fluvial and pluvial floods in the rain season. Fluvial floods happen from June to August due to heavy rainfalls in upstream of Buer-Hatong and Chaoyang Rivers. The pluvial floods are caused by out-dated drainage p systems that have inadequate
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drainage capacity to cope with stormwater from both build-up areas and surrounding hills/mountains during heavy summer rainstorms. Furthermore, the combined drainage/sewers system is also discharging polluted stormwater and sewerage directly into rivers. This component is aims at improvement of water related climate resilience through integration of flood risk management with ecological river rehabilitation applying a blue-green infrastructure approach. Subcomponents include: (i) Integrated river rehabilitation and flood risk management at the Chaoyang River west of the industrial park and at the Buer-Hatong River along the north bank of the eastern industrial park reducing fluvial and pluvial flood risks meeting national standards. (ii) Wetland rehabilitation and construction at the Buer-Hatong River south of the western industrial park and at the eastern industrial park including storm water detention and habitat functions to increase the biodiversity of flora and fauna; (iii) Sponge city infrastructure integrating water detention areas i.e. in green parks and sports fields in the urban areas to enhance climate resilience and sustainably reduce flood risk, enhancing the base flow of rivers; (iv) Collection and biological treatment of the first flush of stormwater discharged from drainage pipes and combined sewer and drainage overflow; (v) Pedestrian and bicycle pathways (and one narrow service road at the eastern industrial park) along ecologically landscaped river greenways to enhance urban liveability; and (vi) Improve the awareness and build capacity in climate change resilience, flood and water and environment resources planning and management.
2.1 Climate risk assessment for integrated Chaoyang river rehabilitation and flood management.
122. The main river rehabilitation work will be the lower reach of the Chaoyang River. The total length of the river is 75 km with a catchment area of 775 km2. A reservoir is built in the middle section of the river, which is the main water supply source of Yanji city. The total water storage of the reservoir is 63 million m3 with a dam constructed for flood at 50 year’s recurrence interval. Embarks of river lower reach is currently built at 20 year’s recurrence interval. Chaoyang River is confluence with Buer-Hatong River in the west end of Yanji city. A newly developed industrial park is located in the east of lower Chaoyang River, which is the terminal of the proposed BRT in the west. Five BRT stations will be built in the industrial park along the Chaoyang River. There are also NMTs built along the river bank and within the industrial park.
123. The current peak flood discharge rates are shown in Table 6 for different river sections and different return periods respectively (Yanji city Flood Protection Plan 2016). As shown in the table, Wudao reservoir is also an important flood protection facility.
124. A recent flood event for Chaoyang River and the industrial park was observed in July 2017. Heavy rainfall fell in upstream of the river catchment forced emergent discharge from the Wudao Reservoir. We were advised that flood water penetrated the river embark in the lower reach of Chaoyang River briefly but conceded quickly. The Wudao Reservoir record showed that from 20-22 July 2017, the upstream inflow rate to the reservoir was 1040 m3/s that was classified as 100 years return period event. The discharge from the reservoir was 367 m3/s that was classified as 20 years return period discharge rate but actually lower than the peak rate of 440 m3/s as shown in Table 6 that assessed by the Yanji city Flood Protection Plan (2016). This suggest that the embark of lower Chaoyang River may actually not meet its design standard of 20 year return period. 34
Table 6: Current flood peak discharge rate assessment (m3) for different sections of Chaoyang River Catchment Area Return Period (yr) River Section (km2) 100 50 20 10 5 Above Wudao Reservoir 595 1160 909 599 389 209 Wudao Reservoir discharge 595 909 600 440 210 120 Reservoir - Confluence 180 381 194 297 124 65 Confluence 775 1290 897 634 334 185 Source: Yanji city Government.
125. Based on the future climate change projections, the modeled flood peak flow rates will increase for both catchments above and below the reservoir significantly, hence at the confluence of Chaoyang River and Buer-Hatong River. Table 7 shows the future Chaoyang River peak flood discharge rates at its confluence with Buer-Hatong River under different climate scenarios and projection periods respectively. Taking projections from rcp45 for 2050, the peak flood discharge rate will increase 11.35%, 12.28%, 12.93%, 13.50%, and 13.88% for return periods of 5, 10, 20, 50, and 100 years, respectively.
Table 7: Impact of climate change on peak flood discharge rates for Chaoyang River at different return periods based on the current assessment and the impact of the various climate projections (flood discharge rate units in m3s-1). Confluence at Buer-Hatong River Return Period(year) Climate scenarios 100 50 20 10 5 Current (m3/s) 1290 897 634 334 185 2030 Rcp45 1386 962 678 356 196 2050 rcp45 1469 1018 716 375 206 2090 rcp45 1442 1004 710 375 208 2030 rcp85 1372 953 673 354 196 2050 rcp85 1460 1015 717 377 209 2090 rcp85 1484 1037 739 393 220 Source: Yanji city Government.
126. Based on above analysis and risk assessment, it is important to take account of both climate changes caused increment in flood levels but also the current situation and previous flooding events in developing adaptation options for flood risks of Chaoyang River rehabilitation. Raising the flood protection design standard is probably the most effective adaptation measure.
2.2 Climate risk assessment for integrated rehabilitation and flood management at Guangjin Creek, Xinxing Creek, and Donxing Creek.
127. The natural drainage system of Yanji is consisting of a number of small creeks/catchments. As a result of urbanization, those creeks are often converted to underground tunnels.
128. Of the three creeks being rehabilitated in this project, Guangjin Creek and Xinxing Creek are mostly underground tunnels whilst Dongxing Creek is still open. A common characteristic is that they all receiving stormwater from both up catchment areas and pipelines from the buildup
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areas of their lower catchment through either combined or separate stormwater/sewer system. Urban road flooding is also a major climate risk to those creeks.
129. One of the major objectives of rehabilitating those three creeks is aimed at reducing pollutant from combined sewer pipelines to the creek and river system and solves the urban road flooding problem. Serious urban road flooding sites are located in the Guangjin Creek catchment area and in the Dongxing Creek catchment area. Those urban flooding issues may be caused by either excess flood water from upstream or by insufficient drainage pipelines.
130. Table 8 shows the current peak flood rates assessed for different return periods by Yanji city Flood Protection Plan (2016). For Guangjin Creek, most areas are buildup already. There is not any open streamline in the catchment already but only pipes and tunnels. With a smaller catchment area, Xinxing creek is similar to Guangjin Creek but with higher buildup intensity. Dongxing Creek has the largest catchment area among the three creeks and less proportion of the catchment are buildup. It still has an open canal confluence with Yanji River.
Table 8: Current flood peak discharge rate assessment (m3) for different sections of Guangjin, Xinxing, and Dongxing creeks Catchment Area Return Period (yr) Creek (km2) 100 50 20 10 5 Guangjin Creek 5.01 26.9 22.6 16.6 12.3 7.92 Xinxing Creek 2.07 13.7 11.5 8.50 6.35 4.19 Dongxing Creek 13.73 73.1 61.6 45.4 33.7 21.9 Source: Yanji city Government.
131. Similar to the Chaoyang River, peak flooding rates of those three creeks will also increase under the future climate projections. Those projected peak flood rates in 2050 are shown in Table 9 that are assessed with RCP4.5 climate change scenarios. Compared with the current assessment, the peak flood flow rates of those three creeks will increase for 11-13% for flood event at 20 years return period in 2050. This requires adaptation measures for not only the main creek/tunnel but also associated stormwater drainage pipelines.
Table 9 Projected peak flood rates in 2050 for different return periods under RCP4.5 climate change scenarios for Guangjin, Xinxing, and Dongxing Creeks Catchment Area Return Period (yr) Creek (km2) 100 50 20 10 5 Guangjin Creek 5.01 30.6 25.7 18.7 13.8 8.8 Xinxing Creek 2.07 15.6 13.1 9.6 7.1 4.7 Dongxing Creek 13.73 83.2 69.9 51.3 37.8 24.4
132. SWMM hydrology and hydraulic models have been set up to assess the flood risks of the initial FSR designs for those three creeks. Those models are set up with the initial FSR designed drainage pipelines because there is not existing pipeline data available. The design standard of FSR is for 3 years rainfall events. This is rather low compared with the creek flood control plan but meet the drainage pipeline design standards. The initial Guangjin Creek model is shown in Figure 8, which simulated a rainfall event at three years return period. Whilst most of the pipelines are sufficiently designed for this rainfall event, there is one manhole being flooded significantly, which also caused large flooding areas (in blue colours) along the Guangjin Road. The FSR 36 designs for the two other creeks are also tested with SWMM models for three year’s rainfall event but no flood was found.
Figure 8: SWMM modelled flooding risk areas of initial pipeline designed in the FSR
3. Climate risks assessment for Component 3 - Water supply system improved
133. The safe and climate-resilient water supply component will be supporting the Yanji Water group Company Limited (the Company) actions to reduce non-revenue water (NRW). The project will help Yanji city from the challenge from limited available water during the dry season.
134. Currently the total annual water supply is 54.65 million m3 (2018 data), to which 37.00 and 17.65 million m3 are sourced from Wudao reservoir and Yanhe Reservoir, respectively. However, average 51% of the total water supplied became non revenue water (NRW) based on three years data from 2015 to 2017, as a result of aged water supply facilities such as leaking pipes, taps, and inaccurate meters.
135. The high ratio of NRW is not only costly to the water supply company but also causing water shortages if there is an extended drought period. In Yanji, there is a long dry period from October to April. Reservoirs have to store sufficient water for those months from the rainy season from May to September. Water shortage will happen if May and June are dry in the coming year due to total storages of both reservoirs are fairly small. For example, the effective storage of Wudao Reservoir is 51 million m3 but responsible for an annual water supply for 37 million m3. Water shortages may happen when there are consecutive dry years or extended dry seasons. Therefore, it is important for the water supply company to reduce NRW and save limited water resources.
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136. The analysis described in this report indicates that changes in water availability are positive for the water supply in Yanji as a result of projected increases in precipitation. However, the population of the city is also projected to increase according to the Master Plan (2013–2030). Therefore, appropriate adaptation measure, especially fixing those leaking pipes and accurate metering, are still very important.
F. Climate Adaptation Options for Project Subcomponents
137. According to climate risks assessed for different component, there are significant adaptation needs for many project subcomponents. The overall concept of this project is to focus on the BRT going east-west along the Buer-Hatong River and then turn north along the Chaoyang river in the west and through the industrial park and integrate all other components generally in this area for both adaptation of existing urban areas and newly planned urban development along the east-west orientation of the future Yanji city, from the previous north-south oriented Yanji. Therefore the adaptation options have been developed along the BRT route, for areas from Chaoyang River in the west to Guangjin Creek in the east, including catchment areas of other two creeks in the north of Guangjin Creek.
1. Climate adaptation options for Component 1 - Low-carbon urban mobility with sustainable integration of multiple traffic modes promoting transit- oriented urban development
138. Urban road flooding is assessed the major climate risk to the proposed BRT route, which is the core function the Component 1 and the project. The initial FSR was designed to build new sewer pipelines and larger stormwater drainage pipelines along the BRT route from the west to east, to resolve the road flooding problem. This designed was questioned during the Interim Mission. The CRA team worked with LDI and government on this issue since the Interim Mission.
1.1 Urban flooding sites analyses
139. Figure 9 shows a 3D map for the topography and natural drainage system of Yanji city, overlaid with the planned road system (orange), available drainage pipelines (blue) and major rivers (dark blue). As shown in Figure 9, Yanji city is located in a valley surrounded by mountains/hills with Buer-Hatong and Yanji Rivers cross the middle of the city. There are a number of small creeks flow to the three rivers of Yanji city. Each of those creeks represents a natural drainage basin.
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Figure 9: Topography and urban areas of Yanji City
140. The SWMM model diagram Figure 10 shows that all pipelines are flowing from west to east or from north to south then east to the main outfall is located in the east of the city, where is close to the wastewater treatment plant. This design is a result of combined stormwater and sewerage system and a gradual urbanization process. This leads to stormwater flow a long distance to reach the main outfall on the Buer-Hatong River in the east. This design made the stormwater management very difficult in the city. The longer the pipe is, the more stormwater accumulated, and the higher flooding risks. This is why deep inundations happens in some low areas along the Buer-Hatong Rover although two meters pipes have been built already. Therefore, the fundamental issue is the inappropriate design of the pipelines rather than the sizes of the pipes. A drainage network consistent with the natural drainage system will be much more efficient and may not need big pipes.
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Figure 10: The north Yanji city SWMM model diagram
141. Therefore, the stormwater drainage network of Yanji will be more efficient if the large connected network is broken into many small systems that are consistent with natural drainage basins. The stormwater flow length will be much shorter than the current system, and may not require very big pipes either. The integrated rehabilitation of three smaller creeks in this project is demonstrating how this concept works. Each of those creeks represents a small stormwater drainage system within s small drainage basin. The demonstration has also considered the first flush treatment issue by integrating sponge city infrastructure (or LID) into the system.
1.2 Adaptation options
142. The modelling outcomes and analyses are well received by the government, LDI and TRTA consultants. Therefore, a combined effort has been made in developing adaptation measures for the road flooding risks of the BRT route, and further extended to further urban development planning for north Yanji. Consequently, two concept plans have been developed. One is the north Yanji stormwater drainage plan, and the other is the sponge city infrastructure development plan for north Yanji. Both of them are developed in accordingly with Yanji’s natural drainage basins.
143. The north Yanji stormwater drainage network plan is illustrated in Figure 11 Based on discussions with CRA and TRTA consultants, LDI suggests to add on a number of outfalls along Chaoyang River and Buer-Hatong River, together with north-south oriented stormwater pipelines linking to those outfalls. The existing west-east oriented pipelines may be transformed to independent small drainage networks by connecting the existing west-east oriented pipelines.
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144. The Yanji government has commissioned a pipeline survey in order to develop more robust city-wide drainage network database. This will enable the project to transforming the existing network based on this plan during the implementation stage. A hydraulic model TA is also planned for the implementation stage to support the LDI design.
Figure 11: The concept plan for developing/transforming the stormwater drainage network for north Yanji city.
1.3 Adaptation measures for the integrated Chaoyang River rehabilitation
145. The initial intentions for the integrated Chaoyang River rehabilitation were to raise the flood protection capacity of the lower Chaoyang River by using ecological designs. The initial FSR design was to maintain the flood protection standard at 20 years return period but rehabilitating/replacing the concrete panel river embark with more environment friendly material so that grasses grow on the embark.
146. After modeling the future peak flood discharge rates using projected climate scenarios, three different adaptation options were developed collaboratively between the CRA team and relevant TRTA specialists, together with LDI and government. These were: (i) Raise the flood protection standard from the current 20 years to 50 years return period, together with other ecological measures to allow grasses grow on the embark. This requires widening the existing river embark from 3 meters to 6 meters; (ii) Maintain the current 20 years flood protection standard but develop a 46.6 ha wetland/flood plain in the left side close to the corner of Chaoyang River and Buer- Hatong River; (iii) Raise the flood protection standard from the current 20 years to 50 years return period and also develop a 46.6 ha wetland/flood plain as recreational park in the city’s west.
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147. After considering the climate risks and project budget, it is agreed by all parties to adopt option one. This will widen the existing river embark and rehabilitation the concrete panel in the inner embark with more ecologically material. The wetland/recreational park idea was highly appreciated by the government but this project cannot afford the investment. Therefore, it becomes a plan for the government for future development options.
148. From the flood protection point of view, option one is sufficient to protect the industrial park and nearby residential zones from flood.
1.4 Adaptation options for Guangjin Creek, Xinxing Creek, and Dongxing Creek
149. SWMM models were developed for catchment areas of Guangjin Creek, Xinxing Creek, and Dongxing Creek respectively, in order to develop appropriate adaptation options for those project subcomponents. Those models simulated the impact of sponge city infrastructure on stormwater management, together with rainfall runoff, drainage pipelines, as well as drainage pipelines designed in the FSR.
150. Guangjin Creek. First of all, the pipeline from the flooding manhole is modified accordingly, as shown in Table 10. The only modification is connecting the elbow style pipe to the manhole in the south side where is the covered tunnel of the Guangjin Creek. This makes it a strait pipeline from north to south and flows from high manhole to a lower node too.
151. Sponge city infrastructure is proposed from the beginning of the project as an adaptation measure to relief the urban flooding. The major sponge city infrastructure in this study are bio- retention cells and permeable pavement car parks. In Chinese term, the bio-retention cells are called sunken rain garden. The stormwater of the residential complexes flows first to, and fill, those sunken rain gardens before it effluence to the stormwater drainage pipes.
152. A total of 8,500 m2 of bio-retention cells and 5600 m2 of permeable pavement (car park) are designed to be built in 8 different residential complexes of the lower Guangjin Creek (Figure 32). Those residential complexes are located in various subcatchments of the model and the proportion of sponge city infrastructure in each subcatchment is different. Therefore, their impact on stormwater behaviour is also varied to different subcatchment. 42
Table 10 Sponge city Infrastructure areas and types in residential complexes of Guangjin Creek Guangjin Creek Rain Garden (bio- Permeable pavement retention Cell) M2 Car park M2 东部家园 800.00 500.00 妇幼保健所 - 1,200.00 月光花苑 1,000.00 600.00 1领域东城2期 1,000.00 600.00 2领域东城 2,000.00 600.00 3东珠家园 1,500.00 800.00 3秋韵雅苑西区 1,200.00 800.00 宏源小区 1,000.00 500.00
Total 8,500.00 5,600.00
Figure 12: SWMM modelled areas subject to floods with 1:50 years’ rainfall event
153. The updated SWMM model with corrected pipeline and sponge city infrastructure are tested with daily rainfall events at 1, 3, 5, 10, 20, and 50 years return period. There is not flood when modeeled with 1:10 years’ rainfall event. When modelled with 1:20 year’s rainfall event, there are two manholes subject to minor floods, with an estimated total flood water volume of 61m3. Figure 32 shows the modelling results for 1:50 year’s rainfall event, in which three areas are subject to minor floods, with estimated total flood volumes of 298m3, 40m3, and 200m3 respectively. Such floods are far smaller than many current flooding sites in nortn Yanji and will not really effect the normal urban life at all. This suggest that FSR designed drainage network for Guangjin Creek is very effective although it is designed for 1:3 years rstandard but capable of cope with rainfall events up to 1:50 years’raianfall event.
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154. The impact of sponge city infrastructure on stormwater flow are also analysed based on the SWMM modeling results. The impact of sponge city infrastructure in individual sub- catchments are varied. This is probably affected by the proportion of sponge city infrastructure within the whole sub-catchment, sponge city infrastructure type, as well as the sub-catchment surface condition. In general, the more sponge city infrastructure constructed, the less total flow volumes and the lower peak flow rate. Figure 13 shows the percentages of peak flows and total flow volumes reduced by sponge city infrastructure in various sub-catchments of Guangjin Creek model.
Figure 13: Percentages of peak flow rates and total flow volumes reduced by sponge city infrastructure in various sub-catchment in Guangjin Creek model. Each label on X axis shows a representative sub-catchment in the model.
155. The modeling outcomes demonstrated that sponge city infrastructure can generate significant impact on the stormwater peak flow rates and total flow volumes. The stormwater management in Yanji can be significantly improved by a combination of properly designed pipeline network and designed sponge city infrastructure. It is possible to optimize the investment by balancing the costs of pipeline network and sponge city infrastructure.
156. Xinxing creek has got higher density of buildings and less available spaces for sponge city infrastructure. It is also not possible to open up the current tunnel. Therefore, adaptation options for Xinxing Creek included constructing separate sewer and stormwater pipelines and a bio-detention ponds in the lower reach of the creek as treatment for the first flush of stormwater.
157. Similar to the Guangjin Creek, a SWMM model was developed for Xinxing Creek to support the climate risk assessment and development of adaptation options. The model included FSR designed drainage pipelines and the existing tunnel to Yanji River. The model was also run 44 with 40 years observed climate data series and daily rainfall events at 1, 3, 5, 10, 20, and 50 years return period. The projected daily rainfall events under RCP45 climate change scenario in 2050 are also applied to the SWMM model to assess the future climate risks.
158. Figure 14 shows the modelling results of Xinxing creek SWMM model with 1:50 years’rainfll event, in which there are only two manhole subject to minor flood risks. Similar to Guangjin Creek, the modeling results suggested that the FSR pipelines for Xinxing Creek are also capable of to resist rainfall event up to 50 years return period although it was designed for only 3 years return period. This is a significant adaptation measure and integrated into final FSR.
Figure 14: The Xinxing Creek SWMM model with FSR designed drainage network
159. Dongxing Creek. Different from the other two creeks, Dongxing Creek is still an open river with open rectangle canals in the urbanized areas. There are also more spaces in the residential complexes. The initial adaptation measures include: (i) Constructing separate drainage and sewers pipeline networks (ii) Developing sponge city infrastructure in residential complexes where is appropriate (iii) Constructing a bio-detention pond in the in the middle of the creek before it flows into the open rectangle canal.
160. The Dongxing Creek SWMM model is set up slightly different from the two others reported earlier. The 1D model covers the whole catchment whilst the 2D model (Figure 15) is setup for only the urban areas in the lower catchment where new stormwater pipelines and sponge city infrastructure are designed in the FSR. The runoff from upstream is set as inflow to the 2D model that is aimed to simulate/assess the initial designed pipelines as well as the open channel of the creek.
161. The white circle in the SWMM 2D model (Figure 15) highlights the manhole that is subject to minor flood risk when modelled with 1:50 years’rainfall event. Similar to other two creeks, the FSR design is capable of coping with 1:50 years’rainfall event although it was designed for only 3 years return period.
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Figure 15: Dongxing Creek SWMM models: 1D model (left) covers the whole catchment and 2D model (right) covers only the urbanised areas
Table 11: Sponge City Infrastructure Designed for Dongxing Creek Drainage itches m Rain garden ㎡ Porous pavement ㎡ Shenhuan 550 1500 1300 Ruifeng 2000 1200 Shuian 1200 1080 Yanbei 2300 1000 Danyan 2500 1300
162. The sponge city infrastructure designed for Dongxing creek is shown in Table 1. Those are all located in the residential complexes in the lower catchment of Dongxing Creek. The SWMM modeling results shown similar impact of the sponge city infrastructure on infiltration, runoff and peak flow rate in Dongxing Creek. The impact of sponge city infrastructure on total and peak flow of Dongxing creek is summarised in Figure 16. 46
Figure 16: The impact of sponge city infrastructure to stormwater in three sub- catchments of Dongxing Creek
2. Safe and climate-resilient water supply and wastewater management systems
163. Adaptation options for safe and climate-resilient water supply component were aimed at raising water use efficiency for the water supply system. Those included measures for reducing leaking and improved measuring and monitoring of water supplies: (i) Installation of about 330 flow meters; (ii) Upgrade and replacement of about 31.64 km water supply pipes; and (iii) Replacement of about 4,000 water meters in the older residential areas.
164. With those adaptation measures, it is estimated that the non revenue water (NRW) will reduce from the current 46% to 37%. This is approximately 4.81 million m3 water resource22, of which 3.19 million m3 for Wudao Reservoir and 1.62 million m3 for Yanhe Reservoir, respectively. will be saved from waste to improve the sustainability of water supply in Yanji city. In addition to water saving, those measures will also provide support for improved planning and management as a result of more effective measuring and monitoring of water supply activities.
22 This is based on the annual water consumption amount from reservoirs from the year 2016 to 2018 in Yanji city.
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3. Non-structural adaptation options - Capacity in low-carbon and climate- resilient city planning and infrastructure management developed
165. The adaptation options developed for the BRT, river and creek rehabilitations have set models for the government in managing fluvial and pluvial floods in Yanji city. The final FSR design with adaptation options for Guangjin Creek is an excellent prototype for Yanji city to manage many of the small creeks that are confluence to Chaoyang River, Buer-Hatong River, and Yanji River. This prototype integrated gray and green infrastructure to address both urban flooding and water pollution issues. A further development plan was also developed for all other creeks in the north of Buer-Hatong River (Figure 17). This plan will be further developed during the project implementation phase with support of a number of capacity building activities.
Figure 17: Sponge city infrastructure development plan for north Yanji
166. During the implementation phase, there will be further support for implementing many designed adaptation options and further development of relevant plans. Those include: (i) Urban Climate Change Adaptation and Sponge City Action Plan preparation including hydraulic modelling and simulation (ii) Low-Carbon City Action Plan preparation for Parking Management Study and for BRT operation capacity development and BRT network planning and Pedestrian and Bicycle and Universal Design Master planning; (iii) Water Safety Plan Preparation and NRW reduction and leakage identification
167. Those action plans and technical support in climate change adaptation, hydraulic modelling, and sponge city infrastructure development will support the government in building low-carbon climate resilient city and optimizing investment in gray-green infrastructure for addressing climate risks and/or urban flooding issues for not only areas with project investment but also wider Yanji city.
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G. Account for Climate Finance and Estimate GHG Emission
168. This project is investing a substantial proportion of funds in climate adaptation and mitigation. The total climate finance of this project accounts for $147.09 million and $82.22 million for adaptation and mitigation respectively, of which $67.75 million and $37.89 million are from ADB, respectively.
169. The climate change adaptation options related investment from ADB finance is summarised in Table 12. The major adaptation option for Component 1 is to construct alternative stormwater drainage pipelines along the BRT route, pipelines between BRT route and Buer- Hatong River for proofing the existing and future road flood risks. This is a substantial adaptation investment but will also fundamentally solve the urban road flooding problem for the north of Buer- Hatong River. This is also an excellent demonstration to the government for solving urban road flooding problem in the south of Buer-Hatong River.
Table 12: Climate Change Adaptation Options Related Investment Financed by ADB Adaptation Target Climate Costs Adaptation Activity Risk ($ million) Adaptation Finance Justification Component 1 - Increasing 30.11 SWMM modelling recommended construct 39,884 m precipitation constructing additional structures in new drainage caused road anticipation of the impact of urban road pipelines along the flooding along the flooding expected under projected climate BRT route BRT route change in the project area. The associated cost of $30.11 million is reported as adaptation finance. Component 2 Increasing rainfall 24.45 WEAP and SWMM modelling construct (i) widen 10 intensity can result recommended the construction of these kilometers of river in extreme additional structures in anticipation of the embankment, (ii) flooding impact of extreme flooding expected sponge city and river/creeks as under projected climate change in the separate storm and well as urban project area. Therefore, the construction sewer pipelines for roads of these structures is an adaptation three creeks activity, and the associated cost of $24.45 million is reported as adaptation finance. Component 3 Increasing temp & 13.19 Climate risks assessment recommended upgrade (i) water precipitation upgrading those structures in anticipation supply facilities, and variability caused of water shortage and increasing (ii) sewers water shortage pollutions. Therefore, the construction of and increasing these structures is considered as wastewater adaptation activity, and the associated cost of $13.19 million is reported as adaptation finance. Source: Asian Development Bank.
170. Adaptation options for Component 2 are aimed addressing both fluvial and pluvial flooding risks in the Chaoyang River and three smaller creeks. The main adaptation option for the integrated rehabilitation of Chaoyang River is to widen the current river embarks to raise the flood protection capacity. The rehabilitation of three smaller creeks adopted more comprehensive adaptation options including separated sewer and drainage pipelines and sponge city infrastructure such as new drainage ditches, rain gardens, porous pavement for parking areas, and detention ponds etc. those have set up models for the government to work with many other
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small creeks to address both fluvial and pluvial flooding risks, as well as pollutions to the water system.
171. For Component 3, all adaptation options are aimed to raise the water use efficiency. Those included upgrading 31.9 km of old leaking pipelines, and install flow meters and replacing old household meters to reduce non revenue water that is currently counting for nearly half of the total treated water supplied into the system. This will not only enable more efficient water use but also reducing costs for water supply.
172. ADB finance a total of $37.89 million to climate change mitigation related investment (Table 13). The major mitigation investment is in Component 1 for promoting sustainable public transport. Those subcomponents include: (i) Modification road for setting up BRT; (ii) Constructing new BRT bus stations (iii) Replacing current diesel buses with hydrogen powered buses. (iv) Constructing non-motorised transit roads that promote walking to BRT buses and cycling etc.
Table 113: Climate Change Mitigation Related Investment Financed by ADB Estimated GHG Estimated Emissions Reduction Mitigation Costs a Mitigation Activity (tCO2e/year) ($ million) Mitigation Finance Justification BRT constructs (i) 25 60,489.90 37.25 The BRT will increase 27,000 bus stations; 55.4 km bus commuters daily to the BRT NMT; (iii) 20 km route and reduce 10,200 private necessary road cars on road. The reduction of upgrade or widening; CO2 emission will result from the and (iv) replacing 100 reduced number of private cars diesel buses with on road and the replacement of hydrogen powered diesel buses with Hydrogen buses; and (v) other powered buses. Therefore, those necessary BRT investments are accounted as management facilities mitigation finance. Increase 18.19 ha 217.92 0.64 Additional tree planting activities trees and other green to be added to the project. areas Related investment is accounted for as mitigation finance. BRT = bus rapid transit, CO2 = carbon dioxide, GHG = greenhouse gas, ha = hectare, km = kilometer, NMT = nonmotorized transport, SWMM = Storm Water Management Model, tCO2e = ton of carbon dioxide equivalent, WEAP = Water Evaluation and Planning System. a Energy savings/year x emission factor = GHG emissions reduction. Source: Asian Development Bank.
173. Table 13 shows also the estimated reduction of GHG emission from this project. The total annual GHG reduction by the project is estimated at 61,246.78 tCO2e/year if diesel buses are replaced by clean energy buses using battery electric buses or at 60,118.5560707.82 if hydrogen buses are used which is a consideration by the government. The BRT is estimated to attract additional 27,000 daily bus commuters compared with the current route. On average, there will be 10,200 less private vehicles on the road. This will reduce 57,418.60 tCO2e/year of GHG emission.
174. The government considers replacement of diesel buses with either electric buses or hydrogen powered buses, which would both be reducing GHG emissions. At this time it is likely 50 that diesel/gasoline buses will be replaced by battery electric buses as this is proven technology and widely available in the PRC. This is estimated to reduce 3,610.26 tCO2e/year compared with current diesel/gasoline buses. This is calculated using outcomes from studies in Shenzhen23 with a total of 16359 battery buses used in public transport system. According to the study, those buses reduce 49.46% of GHG emission compared with diesel/gasoline buses. If at the time of government procurement of the bus fleet for the BRT hydrogen bus technology will be safe, economical and viable, diesel/gasoline powered buses may be replaced by hydrogen fuel cell electric buses which is estimated to reduce GHG emissions by 2,482.03 tCO2e/year. There is no further information regarding GHG emission for these buses and for the calculation outcomes of a study by the Union of Concerned Scientists (USA) was used.24 As there is no tested emssion rate, the computation used was 34% of emission reduction rate for for those hydrogen fuel cell electric buses relative to those diesel/gasoline buses being replaced. Based on surveyed data, it is estimated emission rate is 905 gCO2e/km for these old buses. The emission of the hydrogen fuel cell electric buses is estimated to reduce 307 gCO2e/km or with an emission rate of 598 gCO2e/km.
175. Another small contribution to GHG reduction is from those newly planted trees and grasses in this project.
23 Clean energy motor vehicle development survey in China. 2018. http://www.xinhuanet.com/fortune/2018- 01/12/c_1122248544.htm. 24 Union of Concerned Scientists [USA] How Clean Are Hydrogen Fuel Cell Electric Vehicles? 2014. https://www.ucsusa.org/sites/default/files/attach/2014/10/How-Clean-Are-Hydrogen-Fuel-Cells-Fact-Sheet.pdf.