scholarly journals Water Retention Performance at Low-Impact Development (LID) Field Sites in Taipei, Taiwan

2021 ◽  
Vol 13 (2) ◽  
pp. 759
Author(s):  
Jen-Yang Lin ◽  
Ti-Chi Yuan ◽  
Chi-Feng Chen
Keyword(s):  
Stormwater Management ◽  
Water Retention ◽  
Rainfall Intensity ◽  
Retention Rate ◽  
Low Impact Development ◽  
Drainage System ◽  
Retention Rates ◽  
Retention Performance ◽  
Pervious Pavement ◽  
Taipei City

Low-impact development (LID) aims to retain stormwater at source sites rather than achieve water drainage. The infiltration and storage of rainwater on site is the most commonly applied LID design concept, turning impervious pavements into pervious pavements. In this study, three field sites in Taipei city, Taiwan, were monitored. Two of the sites were located on campuses, and one site was a roadside location. They were constructed at different times and had distinct purposes, but the common design aspect was the infiltration function of the ground surface. We monitored the water retention performance at the above three sites and applied a verified stormwater management model (SWMM) to characterize the performance at these case sites. The observed data show that if the accumulative rainfall was lower than 20 mm, the water retention rate at each of the three case sites reached almost 50%; at 60 mm rainfall, the rate was 40%. With increased rainfall amount, the water retention rate decreased because the storage capacity was limited. Because water retention is typically controlled by the infiltration capacity, the rainfall intensity dominated the performance. At the three field sites, the water retention rate was 40% on average at a rainfall intensity below 20 mm/h. Above this rainfall intensity, the infiltration performance of the pervious pavement decreased. The verified model was applied to assess the performance at the three sites under the Taipei city drainage system design standard, i.e., the five-year recurrent period storm level, at 78.8 mm/h. The results demonstrate that the water retention rates were 9.1%, 14.2%, and 61.0% at the three sites, indicating that the pervious pavement could reduce the loading of the current stormwater drainage system. Dispersed sites should be considered in urban stormwater management to mitigate flooding risk in urban areas.

Benefits of low-impact development in rural areas

2021 ◽  
Author(s):  
Kuan Lin Chou
Keyword(s):  
Decision Making ◽  
Rural Areas ◽  
Urban Areas ◽  
Rainfall Intensity ◽  
Model Simulation ◽  
Low Impact Development ◽  
Drainage System ◽  
Heavy Rain ◽  
The Government ◽  
Rain Events

<p>In Taiwan, it is easy to encounter typhoons or heavy rain events with high rainfall intensity, and urban areas are prone to flooding and causing disasters. Rural areas are no exception. Flooding can cause crop necrosis. The reason may be attributed to the rural areas’s old drainage system or not yet complete drainage system, so the goal is to find the most suitable low-impact development facilities through model simulation, evaluate whether various low-impact developments are feasible, and how much flooding depth and savings can be reduced after installation. How much water is used for future irrigation as a decision-making benefit, and the scope of the setting is planned according to the flow sharing plan set by the government, hoping to provide effective improvement in rural areas.</p>

Enlightenment from ancient Chinese urban and rural stormwater management practices

2013 ◽  
Vol 67 (7) ◽  
pp. 1474-1480 ◽  
Author(s):  
Che Wu ◽  
Mengxi Qiao ◽  
Sisi Wang
Keyword(s):  
Stormwater Management ◽  
Management Practices ◽  
Low Impact Development ◽  
Drainage System ◽  
Complex Environment ◽  
Design Concepts ◽  
Stormwater Management Practices ◽  
The Ancient Chinese ◽  
Sustainable Drainage Systems ◽  
Modern Technologies

Hundreds of years ago, the ancient Chinese implemented several outstanding projects to cope with the changing climate and violent floods. Some of these projects are still in use today. These projects evolved from the experience and knowledge accumulated through the long coexistence of people with nature. The concepts behind these ancient stormwater management practices, such as low-impact development and sustainable drainage systems, are similar to the technology applied in modern stormwater management. This paper presents the cases of the Hani Terrace in Yunnan and the Fushou drainage system of Ganzhou in Jiangxi. The ancient Chinese knowledge behind these cases is seen in the design concepts and the features of these projects. These features help us to understand better their applications in the contemporary environment. In today's more complex environment, integrating traditional and advanced philosophy with modern technologies is extremely useful in building urban and rural stormwater management systems in China.

scholarly journals Nitrogen Retention Effects under Reservoir Regulation at Multiple Time Scales in a Subtropical River Basin

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1685
Author(s):  
Meibing Liu ◽  
Xingwei Chen ◽  
Ying Chen ◽  
Lu Gao ◽  
Haijun Deng
Keyword(s):  
Assessment Tool ◽  
Retention Rate ◽  
Nitrogen Retention ◽  
Influential Factors ◽  
Retention Rates ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Retention Performance ◽  
Hydraulic Residence Time ◽  
Lower Velocity

Reservoirs are an important nitrogen sink as a result of their retention effect, but their retention performance may vary with hydrologic conditions with time-varying characteristics, which also change them from being a sink to source over time. This study uses a coupled modelling system (Soil and Water Assessment Tool (SWAT) and a two-dimensional hydrodynamic and water quality model (CE-QUAL-W2) to analyze the nitrogen retention effect and influential factors at annual, monthly, and daily scales in Shanmei Reservoir in southeast China. The results showed that there was a positive retention effect of total nitrogen (TN), nitrate-nitrogen (NO3-N) and ammonia nitrogen (NH4-N) in most years, with average retention rates up to 12.7%, 7.83% and 26.17%, respectively. The reservoir serves mainly as a nitrogen sink at an annual scale. The monthly retention performances of TN and NO3-N were observed during the wet season (April–October) with higher water temperature and lower velocity, while a release effect occurred during the dry season (November–March). For NH4-N, which is prone to nitrification, the retention effect lasted longer, from May to December. The daily nitrogen retention process changed more dramatically, with the retention rate varying from −292.49 to 58.17%. During the period of dispatch, the regulated discharge was the primary factor of daily retention performance, while the hydraulic residence time, velocity and water level were all significantly correlated with nitrogen retention during the period without dispatch.

scholarly journals Construction of Porous Starch-Based Hydrogel via Regulating the Ratio of Amylopectin/Amylose for Enhanced Water-Retention

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3999
Author(s):  
Huiyuan Luo ◽  
Fuping Dong ◽  
Qian Wang ◽  
Yihang Li ◽  
Yuzhu Xiong
Keyword(s):  
Water Retention ◽  
Raw Materials ◽  
Retention Rate ◽  
Fixed Ratio ◽  
Chemical Properties ◽  
Retention Performance ◽  
And Performance ◽  
Traditional Natural ◽  
Water Retention Properties ◽  
Physical And Chemical

The performance of hydrogels prepared with traditional natural starch as raw materials is considerable; the fixed ratio of amylose/amylopectin significantly limits the improvement of hydrogel structure and performance. In this paper, starch hydrogels were prepared by physical blending and chemical grafting, with the aid of ultrasonic heating. The effects of different amylose/amylopectin ratios on the microstructure and water retention properties of starch hydrogels were studied. The results show that an increase in amylopectin content is beneficial to improve the grafting ratio of acrylamide (AM). The interaction between the AM grafted on amylopectin and amylose molecules through hydrogen bonding increases the pores of the gel network and thins the pore walls. When the amylopectin content was 70%, the water absorption (swelling 45.25 times) and water retention performance (16 days water retention rate 44.17%) were optimal. This study provides new insights into the preparation of starch-based hydrogels with excellent physical and chemical properties.

A study on the effects of urban runoff controls in the sandsli research catchment, Bergen, Norway

1997 ◽  
Vol 36 (8-9) ◽  
pp. 379-384
Author(s):  
Sveinn T. Thorolfsson
Keyword(s):  
Ground Water ◽  
Stormwater Management ◽  
Drainage System ◽  
Urban Runoff ◽  
Source Control ◽  
Urban Stormwater ◽  
Urban Stormwater Management ◽  
Water Conditions

This paper describes a case study on a new alternative drainage system for urban stormwater management, the so-called “Sandsli-system”. The aim of this study is to evaluate the Sandsli system and the effects of the solution on ground water conditions. The study is carried out in the Sandsli research catchment in Bergen, Norway. The idea behind the “Sandsli-system is not to mix the polluted and the clean stormwater combined with a source control for both stormwater quantity and quality. The clean stormwater is percolated as quickly as possible, while the polluted stormwater is collected and conducted to an appropriate site for disposal or treatment. The Sandsli-system was developed as an alternative drainage system to the conventional drainage system. The system has been functioning satisfactorily since 1981 to date. The advantages of the use of the Sandsli-system is highlighted i.e. recharging the stormwater to the ground water. The Sandsli-system is appropriate to locations with climate and geology similar to that found in the coastal part of Norway

scholarly journals The model and simulation of low impact development of the sponge airport, China

2019 ◽  
Vol 20 (2) ◽  
pp. 383-394 ◽  
Author(s):  
Jing Peng ◽  
Jiayi Ouyang ◽  
Lei Yu ◽  
Xinchen Wu
Keyword(s):  
Flood Control ◽  
Low Impact Development ◽  
Water Environment ◽  
Drainage System ◽  
Practical Significance ◽  
International Airport ◽  
Model And Simulation ◽  
Impervious Area ◽  
Before And After ◽  
Airport Runway

Abstract Recently urban waterlogging problems have become more and more serious, and the construction of an airport runway makes the impervious area of the airport high, which leads to the deterioration of the water environment and frequent waterlogging disasters. It is of great significance to design and construct the sponge airport with low impact development (LID) facilities. In this paper, we take catchment N1 of Beijing Daxing International Airport as a case study. The LID facilities are designed and the runoff process of a heavy rainfall in catchment N1 is simulated before and after the implementation of LID facilities. The results show that the total amount of surface runoff, the number of overflow junctions and full-flow conduits of the rainwater drainage system in catchment N1 of Beijing Daxing International Airport are significantly reduced after the implementation of the LID facilities. Therefore, the application of LID facilities has greatly improved the ability of the airport to remove rainwater and effectively alleviated the risk of waterlogging in the airport flight area. This study provides theoretical support for airport designers and managers to solve flood control and rainwater drainage problems and has vital practical significance.

A Systematic Review on Extracellular Vesicles-Enriched Fat Grafting: A Shifting Paradigm

2020 ◽  
Author(s):  
Mohammad Ghiasloo ◽  
Laura De Wilde ◽  
Kashika Singh ◽  
Patrick Tonnard ◽  
Alexis Verpaele ◽  
...  
Keyword(s):  
Systematic Review ◽  
Graft Survival ◽  
Extracellular Vesicles ◽  
Retention Rate ◽  
Fat Grafting ◽  
Retention Rates ◽  
Fat Graft ◽  
Cochrane Central Register

Abstract Background Recent evidence confirms that mesenchymal stem cells (MSCs) facilitate angiogenesis mainly through paracrine function. Extracellular vesicles (EVs) are regarded as key components of the cell secretome, possessing functional properties of their source cells. Subsequently, MSC-EVs have emerged as a novel cell-free approach to improve fat graft retention rate. Objectives To provide a systematic review of all studies reporting the use of MSC-EVs to improve graft retention rate. Methods A systematic search was undertaken using the Embase, PubMed and the Cochrane Central Register of Controlled Trials databases. Outcome measures included donor/receptor organism of the fat graft, study model, intervention groups, evaluation intervals, EV research data, in vitro and in vivo results. Results Of the total 1717 articles, 62 full-texts were screened. Seven studies reporting on 294mice were included. Overall, EV treated groups showed higher graft retention rates compared to untreated groups. Notably, retention rate was similar following EV- and MSC-treatment. In addition to reduced inflammation, graft enrichment with EVs resulted in early revascularization and better graft integrity. Interestingly, hypoxic preconditioning of MSCs improved their beneficial paracrine effects and led to a more proangiogenic EV population, as observed by both in vitro and in vivo results. Conclusions MSC-EVs appear to offer an interesting cell-free alternative to improve fat graft survival. While their clinical relevance remains to be determined, it is clear that not the cells, but their secretome is essential for graft survival. Thus, a paradigm shift from cell-assisted lipotransfer towards ‘secretome-assisted lipotransfer’ is well on its way.

scholarly journals Near-falls in Singapore community-dwelling older adults: a feasibility study

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Shawn Leng-Hsien Soh ◽  
Chee-Wee Tan ◽  
Judith Lane ◽  
Ting-Ting Yeh ◽  
Benjamin Soon
Keyword(s):  
Older Adults ◽  
Retention Rate ◽  
Community Dwelling ◽  
Retention Rates ◽  
Reach To Grasp ◽  
Balance Recovery ◽  
Recruitment And Retention ◽  
Body Regions ◽  
Near Falls ◽  
Community Dwelling Older Adults

Abstract Background A near-fall is defined as a loss of balance that would result in a fall if sufficient balance recovery manoeuvres are not executed. Compared to falls, near-falls and its associated balance recovery manoeuvres have been understudied. Older adults may not recognise a near-fall or identify the use of their balance recovery manoeuvres to prevent a fall. The consensus on the methods to collect near-fall data is lacking. The primary objective of this study was to determine the feasibility of recruitment and retention. Secondary objectives were to establish evidence that Singapore community-dwelling older adults can identify near-falls and associated balance recovery manoeuvres. Texting and calling methods were explored as reporting methods. Methods This study took place in Singapore (September to October 2019). Participants were healthy, community-dwelling adults aged 65 or older. Recruitment was done through poster advertisement, and all participants gave informed consent. Participants attended a briefing session and reported their near-fall or fall incidence over 21 days using either daily texting or calling. The primary outcome measures were the recruitment rate, retention rate, preferred modes for data reporting and ability to report near-falls or falls. Secondary outcomes included the self-reported incidence of falls and near-falls. Results Thirty older adults were recruited in 5 weeks. All participants completed the study. They understood near-fall concepts and were able to report the occurrence and relevant balance recovery manoeuvres used to prevent a fall. 87% (26/30) chose to text while 13% (4/30) selected calling as their reporting method. One actual fall (0.16%) out of 630 responses was reported. Thirty-six incidents (5.7%) of near-falls were recorded. Sixteen participants (53.3%) experienced near-falls and half of this group experienced two or more near-falls. The use of reach-to-grasp strategy (36%), compensatory stepping (52.8%), and other body regions (11.2%) were used to prevent the fall. Conclusions The study provided evidence that studying near-falls in Singapore community-dwelling older adults is feasible and can be applied to a large-scale study. Recruitment and retention rates were good. Older adults were able to identify near-falls and balance recovery manoeuvres. Both texting and calling were feasible reporting methods, but texting was preferred. Trial registration ClinicalTrials identifier: NCT04087551. Registered on September 12, 2019

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