Experimental Testing for Evaluating the Influence of Substrate Thickness on the Sub-Surface Runoff of a Green Roof

2015 ◽  
Vol 737 ◽  
pp. 705-709 ◽  
Author(s):  
Marco Carbone ◽  
Gennaro Nigro ◽  
Giuseppina Garofalo ◽  
Patrizia Piro

Green roofs (GRs) represent one of the most widespread Low Impact Development (LID) techniques, although the lack of adequate modeling tools is a limiting factor in the diffusion of such practices. GRs may represent a solution for minimizing the impact of urbanization on the hydrological cycle and for sustainably managing water resources in urban environment. Several studies have shown that GRs effectively control surface runoff in urban drainage system reducing overall volumes and peak flow rates. The performance of a GR is strongly dependent upon substrate soil depth. The understanding of infiltration phenomena in soil medium is one of the most important factors in the LID’s hydrological behavior analysis. In this study the hydrologic/hydraulic behavior of a GR for varying substrate thicknesses and constant rainfall intensities, ranging from 45 to 130 mm/h is tested. The results show that sub-surface runoff is linearly influenced by substrate thickness.

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3636
Author(s):  
Adeline Umugwaneza ◽  
Xi Chen ◽  
Tie Liu ◽  
Zhengyang Li ◽  
Solange Uwamahoro ◽  
...  

Droughts and floods are common in tropical regions, including Rwanda, and are likely to be aggravated by climate change. Consequently, assessing the effects of climate change on hydrological systems has become critical. The goal of this study is to analyze the impact of climate change on the water balance in the Nyabugogo catchment by downscaling 10 global climate models (GCMs) from CMIP6 using the inverse distance weighting (IDW) method. To apply climate change signals under the Shared Socioeconomic Pathways (SSPs) (low and high emission) scenarios, the Soil and Water Assessment Tool (SWAT) model was used. For the baseline scenario, the period 1950–2014 was employed, whereas the periods 2020–2050 and 2050–2100 were used for future scenario analysis. The streamflow was projected to decrease by 7.2 and 3.49% under SSP126 in the 2020–2050 and 2050–2100 periods, respectively; under SSP585, it showed a 3.26% increase in 2020–2050 and a 4.53% decrease in 2050–2100. The average annual surface runoff was projected to decrease by 11.66 (4.40)% under SSP126 in the 2020–2050 (2050–2100) period, while an increase of 3.25% in 2020–2050 and a decline of 5.42% in 2050–2100 were expected under SSP585. Climate change is expected to have an impact on the components of the hydrological cycle (such as streamflow and surface runoff). This situation may, therefore, lead to an increase in water stress, calling for the integrated management of available water resources in order to match the increasing water demand in the study area. This study’s findings could be useful for the establishment of adaptation plans to climate change, managing water resources, and water engineering.


2015 ◽  
Vol 737 ◽  
pp. 749-753 ◽  
Author(s):  
Marco Carbone ◽  
Giuseppina Garofalo ◽  
Gennaro Nigro ◽  
Patrizia Piro

Green roofs (GRs) may represent a solution for minimizing the impact of urbanization on the hydrological cycle and for sustainably managing water resources in urban environment. Several studies have shown that GRs effectively control the surface runoff conveyed into the combined sewer systems, by reducing overall volumes and peak flow rates. The hydrological/hydraulic performance of a GR is strongly dependent upon vegetation species used. In this study the influence of plants on the sub-surface runoff is investigated by monitoring two experimental GRs in wet weather conditions. It is hypothesized that although plants reduce sub-surface runoff, they may also boost the formation of preferential flow paths. The results showed that the sub-surface runoff is strongly influenced by vegetation. While for smaller storm events the GR highly retains stormwater due to the plant interception, for larger storm events the GR’s performance decreases due to the increase of sub-surface runoff. This may be due to the presence of the plant root which produces preferential macropores flow through the substrate.


2018 ◽  
Vol 196 ◽  
pp. 03014 ◽  
Author(s):  
Paweł Gilewski ◽  
Arkadiusz Węglarz

Civil engineering structures are highly responsible for the negative aspects of urbanization on the hydrological cycle. Due to the land cover change and an increase of impervious areas the risk of flooding can rise significantly. The paper presents the impact of urbanization processes on surface runoff estimation for a small mountainous catchment between 1990-2012.


Land ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 839
Author(s):  
Sabita Shrestha ◽  
Shenghui Cui ◽  
Lilai Xu ◽  
Lihong Wang ◽  
Bikram Manandhar ◽  
...  

Rapid urban development results in visible changes in land use due to increase in impervious surfaces from human construction and decrease in pervious areas. Urbanisation influences the hydrological cycle of an area, resulting in less infiltration, higher flood peak, and surface runoff. This study analysed the impact of land use change due to urbanisation on surface runoff, using the geographic information system (GIS)-based soil conservation service curve number (SCS–CN) method, during the period of rapid urban development from 1980 to 2015 in Xiamen, located in south-eastern China. Land use change was analysed from the data obtained by classifying Landsat images from 1980, 1990, 2005, and 2015. Results indicated that farmland decreased the most by 14.01%, while built-up areas increased the most by 15.7%, from 1980 to 2015. Surface runoff was simulated using the GIS-based SCS–CN method for the rainfall return periods of 5, 10, 20, and 50 years. The spatial and temporal variation of runoff was obtained for each land use period. Results indicate that the increase in surface runoff was highest in the period of 1990–2005, with an increase of 10.63%. The effect of urbanisation can be realised from the amount of runoff, contributed by built-up land use type in the study area, that increased from 14.2% to 27.9% with the rise of urban expansion from 1980 to 2015. The relationship between land use and surface runoff showed that the rapid increase in constructed land has significantly influenced the surface runoff of the area. Therefore, the introduction of nature-based solutions such as green infrastructure could be a potential solution for runoff mitigation and reducing urban flood risks in the context of increasing urbanization.


2019 ◽  
Vol 23 (4) ◽  
pp. 1867-1883 ◽  
Author(s):  
Igor Pavlovskii ◽  
Masaki Hayashi ◽  
Daniel Itenfisu

Abstract. Snowpack accumulation and depletion are important elements of the hydrological cycle in the Canadian prairies. The surface runoff generated during snowmelt is transformed into streamflow or fills numerous depressions driving the focussed recharge of groundwater in this dry setting. The snowpack in the prairies can undergo several cycles of accumulation and depletion in a winter. The timing of the melt affects the mechanisms of snowpack depletion and their hydrological implications. The effects of midwinter melts were investigated at four instrumented sites in the Canadian prairies. Unlike net radiation-driven snowmelt during spring melt, turbulent sensible heat fluxes were the dominant source of energy inputs for midwinter melt occurring in the period with low solar radiation inputs. Midwinter melt events affect several aspects of hydrological cycle with lower runoff ratios than subsequent spring melt events, due to their role in the timing of the focussed recharge. Remote sensing data have shown that midwinter melt events regularly occur under the present climate throughout the Canadian prairies, indicating applicability of the study findings throughout the region.


Forests ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 18
Author(s):  
Hadi Sohrabi ◽  
Meghdad Jourgholami ◽  
Mohammad Jafari ◽  
Farzam Tavankar ◽  
Rachele Venanzi ◽  
...  

Soil damage caused by logging operations conducted to obtain and maximize economic benefits has been established as having long-term effects on forest soil quality and productivity. However, a comprehensive study of the impact of logging operations on earthworms as a criterion for soil recovery has never been conducted in the Hyrcanian forests of Iran. The aim of this study was to determine the changes in soil biological properties (earthworm density and biomass) and its recovery process under the influence of traffic intensity, slope and soil depth in various intervals according to age after logging operations. Soil properties were compared among abandoned skid trails with different ages (i.e., 3, 10, 20, and 25 years) and an undisturbed area. The results showed that earthworm density and biomass in the high traffic intensity and slope class of 20–30% at the 10–20 cm depth of the soil had the lowest value compared to the other treatments. Twenty-five years after the logging operations, the earthworm density at soil depth of 0–10 and 10–20 cm was 28.4% (0.48 ind. m−2) and 38.6% (0.35 ind. m−2), which were less than those of the undisturbed area, respectively. Meanwhile, the earthworm biomass at a soil depth of 0–10 and 10–20 cm was 30.5% (2.05 mg m−2) and 40.5% (1.54 mg m−2) less than the values of the undisturbed area, respectively. The earthworm density and biomass were positively correlated with total porosity, organic carbon and nitrogen content, while negatively correlated with soil bulk density and C/N ratio. According to the results, 25 years after logging operations, the earthworm density and biomass on the skid trails were recovered, but they were significantly different with the undisturbed area. Therefore, full recovery of soil biological properties (i.e., earthworm density and biomass) takes more than 25 years. The conclusions of our study reveal that the effects of logging operations on soil properties are of great significance, and our understanding of the mechanism of soil change and recovery demand that harvesting operations be extensively and properly implemented.


Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1210
Author(s):  
Abtin Shahrokh Hamedani ◽  
Arianne Bazilio ◽  
Hanieh Soleimanifar ◽  
Heather Shipley ◽  
Marcio Giacomoni

Low impact development (LID) practices, such as bioretention and sand filter basins, are stormwater control measures designed to mitigate the adverse impacts of urbanization on stormwater. LID treatment performance is highly dependent on the media characteristics. The literature suggests that bioretention media often leach nutrients in the stormwater effluent. The objective of this study was to analyze the treatment performance of different sand and bioretention soil mixtures. Specifically, this investigation aimed to answer whether the use of limestone and recycled glass could improve the treatment performance of bioretention systems. Column experiments were designed to assess (1) the removal efficiencies of different sand and bioretention soil mixtures and (2) the impact of plant uptake on removal rates. Enhanced pollutant removal was observed for the custom blends with addition of limestone sand, indicating mean dissolved and total phosphorus removal of 44.5% and 32.6% respectively, while the conventional bioretention soil mixtures leached phosphorus. Moreover, improved treatment of dissolved and total copper was achieved with mean removal rates of 70.7% and 93.4%, respectively. The results suggest that the nutrient effluent concentration decreased with the addition of plants, with mean phosphorus removal of 72.4%, and mean nitrogen removal of 22% for the limestone blend.


2021 ◽  
Vol 80 (13) ◽  
Author(s):  
Grzegorz Przydatek ◽  
Włodzimierz Kanownik

AbstractThe paper aims to determine the most significant physicochemical indicators of the effects that a lined landfill in southern Poland has had on groundwater quality. The results of the tests of groundwater and leachate water from the landfill for the period 2009 to 2016 were subjected to a detailed statistical analysis based on the 10 physicochemical parameters. A factor analysis was conducted considering the European Union and national requirements for landfills using analytical and statistical tools. The leachate contamination indicators from a landfill were analysed to reveal their interaction with the groundwater. The assessment indicated that there was an elevated and statistically significantly higher electrical conductivity and copper and total organic carbon concentrations in groundwater hydraulically downgradient of the landfill. The assessment also indicated that there were significant differences in the correlations between chemical parameters downgradient of the landfill and that there was a trend of increasing concentrations of some chemical constituents in groundwater. The adverse effects of the landfill were due to the deposited amount of waste exceeding 10 Mg per day. The impact was noticeable despite low and decreasing concentrations of heavy metals (Hg, Cu, Cd, Pb and Zn) in the leachate. The deterioration of the chemical state of the groundwater in the landfill vicinity could result in the extended time of pollutant migration or mass transport in the irrigated soil medium due to the limited efficiency of the leachate intake system or sealing screen after more than 20 years of landfill operation.


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