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1
Yang, Zhuan Yun. "Feasibility Analysis and Status of Shallow Pipe-Jacking Technology in Urban Drainage Systems." Key Engineering Materials 480-481 (June 2011): 1278–82. http://dx.doi.org/10.4028/www.scientific.net/kem.480-481.1278.
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Considering the current domestic situation that there is no provision for shallow pipe-jacking (with overburden soil layer not thicker than 3 m and 1.5 times of the pipe external diameter) in the existing water supply and drainage pipeline engineering design and construction specifications, a comprehensive analysis and discussion, based on the actual domestic condition, is made on the feasibility of shallow pipe-jacking technology in urban drainage systems. The problems confronting the shallow pipe-jacking technology theory research are also analyzed and the research status of shallow curve pipe-jacking technology is introduced.
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Lai, Yue, Yiyun Lu, Tingting Ding, Huiyi Sun, Xuanying Li, and Xiaoyu Ge. "Effects of Low-Impact Development Facilities (Water Systems of the Park) on Stormwater Runoff in Shallow Mountainous Areas Based on Dual-Model (SWMM and MIKE21) Simulations." International Journal of Environmental Research and Public Health 19, no. 21 (November 2, 2022): 14349. http://dx.doi.org/10.3390/ijerph192114349.
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Rapid urbanization has triggered more serious urban flood risks. Many studies have focused on intra-urban flooding, but less attention has been paid to rainfall and flood risks at the urban fringe. Nowadays, China is vigorously promoting the construction of sponge cities in the whole area. It is important to study the construction of sponge cities in shallow mountainous areas, which are an important barrier between cities and mountains. The purpose of this paper is to investigate the performance of Low-Impact Development (LID) facilities under different rainfall scenarios in developed shallow mountainous areas. The second garden and flower exposition (“the Expo Park”) in Hebei Province is used as an example. The SWMM and MIKE21 models were used to simulate the hydrological processes before and after the construction of “the Expo Park”, and the models were calibrated with the measured data. Peak flow rate, outflow volume, rainfall-outflow ratio, runoff velocity, and water feature area of the water system were used as indicators to evaluate their effectiveness. The results showed that the placement of LID facilities had a positive impact on the construction of the shallow mountain area. Specifically, (1) LID facilities can reduce the peak flow rate, delayed peak flow time, outflow volume, and rainfall outflow ratio of stormwater runoff in mountainous areas; and (2) they can effectively collect rainwater and become a supplement to the landscape water system of the site. These findings provide a scientific basis for the construction of LID facilities in shallow mountainous areas, which is important for the development and flood management of shallow mountainous areas.
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Dickman, M. D. "Evidence of Recent Eutrophication of an Urban Lake in Nanjing, China." Water Quality Research Journal 27, no. 2 (May 1, 1992): 311–26. http://dx.doi.org/10.2166/wqrj.1992.022.
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Abstract There is very little known about urban lakes in China, and for this reason this paper provides a synthesis of palaeolimnological and past and present phytoplankton studies of Xuanwu Lake, an urban lake near the center of Nanjing, in Jiangsu Province, China. Documented changes in biotic species diversity and water chemistry in this urban lake over the last thirty years have been attributed to progressive eutrophication associated with lake in-filling, commercial harvesting of plants and fish and intense industrial and urban activities within the lake's watershed. During the last decade, phytoplankton biomass in Xuanwu Lake has increased ten fold. This has resulted in a steady shallowing of the lake's photic zone to a depth of less than 0.7 m with Secchi transparencies of 0.3 to 0.4 m. Wind-generated currents prevent anoxia from occurring in this shallow wind-swept lake no matter how eutrophic the lake. As a result, many of the negative impacts of hypertrophication, such as anoxia, fish kills and noxious odors, are avoided. Thus, shallow lakes like Xuanwu Lake can become eutrophic without producing long periods of hypolimnetic anoxia such as those frequently reported for deeper eutrophic lakes. It was concluded that it is important to treat deep urban lakes differently from shallow urban lakes as the latter systems rarely display extended periods of anoxia, fish kills and noxious odors.
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Silvestri, Vincent. "Performance of shallow foundations on clay deposits in Montréal Island." Canadian Geotechnical Journal 37, no. 1 (February 1, 2000): 218–37. http://dx.doi.org/10.1139/t99-082.
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This paper reports the results of a geotechnical investigation and a 3 year monitoring program of clay deposits in Montréal Island, on which are founded five typical residential buildings. The sites were provided with foundation wall elevation pins, ground movement plates, deep settlement points, piezometers and shallow water level gauges, aluminium tubes for the measurement of volumetric weights and water contents, and irrigation systems. Data recorded show that for the relatively dry summer of 1991 ground and foundation settlements were more pronounced on the nonirrigated sites.Key words: shallow foundations, clay deposits, performance, urban environment, monitoring.
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Wittenberg, H., and H. Aksoy. "Groundwater intrusion into leaky sewer systems." Water Science and Technology 62, no. 1 (July 1, 2010): 92–98. http://dx.doi.org/10.2166/wst.2010.287.
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Vast volumes of groundwater are drained by urban sewer systems. This unwanted flow component intrudes into sewer systems through leaky joints or connected house drains. However, unlike urban storm drainage, it has a high seasonal variation corresponding to groundwater storage and long slow recessions similar to baseflow in rivers also fed by shallow groundwater exfiltrating into the surface waters. By applying the nonlinear reservoir algorithm as used for baseflow separation from total flow in a river, groundwater flow is separated from daily measured influents to treatment plants in Lower Saxony and Baden-Württemberg, Germany and in the Terkos Lake watershed near Istanbul, Turkey. While waste water flows vary only moderately within a year, separated intruded groundwater flows show recessions and seasonal variations correlated to baseflow in neighbouring rivers. It is possible to conclude that recession characteristics of treatment plant influents allow quantification and prediction of groundwater intrusion into sewer systems.
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Alsumaiei, Abdullah A. "A Nonlinear Autoregressive Modeling Approach for Forecasting Groundwater Level Fluctuation in Urban Aquifers." Water 12, no. 3 (March 14, 2020): 820. http://dx.doi.org/10.3390/w12030820.
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The application of a nonlinear autoregressive modeling approach with exogenous input (NARX) neural networks for modeling groundwater level fluctuation has been examined by several researchers. However, the suitability of NARX in modeling groundwater level dynamics in urbanized and arid aquifer systems has not been comprehensively investigated. In this study, a NARX-based modeling approach is presented to establish a robust water management tool to aid urban water managers in controlling the development of shallow water tables induced by artificial recharge activity. Temperature data series are used as exogenous inputs for the NARX network, as they better reflect the intensity of artificial recharge activities, such as excessive lawns irrigation. Input delays and feedback delays for the NARX networks are determined based on the autocorrelation and cross-correlation analyses of detrended groundwater levels and monthly temperature averages. The validation of the proposed approach is assessed through a rolling validation procedure. Four observation wells in Kuwait City are selected to test the applicability of the proposed approach. The results showed the superiority of the NARX-based approach in modeling groundwater levels in such an urbanized and arid aquifer system, with coefficient of determination (R2) values ranging between 0.762 and 0.994 in the validation period. Comparison with other statistical models applied to the same study area shows that NARX models presented here reduced the mean absolute error (MAE) of groundwater levels forecasts by 50%. The findings of this paper are promising and provide a valuable tool for the urban city planner to assist in controlling the problem of shallow water tables for similar climatic and aquifer systems.
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Thomas, K., E. McBean, and H. M. Murphy. "Drinking water quality for peri-urban residents in Phnom Penh, Cambodia." Journal of Water, Sanitation and Hygiene for Development 3, no. 4 (June 8, 2013): 512–21. http://dx.doi.org/10.2166/washdev.2013.126.
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Piped distribution systems are limited to major urban centres in Cambodia, leaving the residents of peri-urban communities to rely on a variety of surface, rain and groundwater sources for their drinking water supplies. This paper examines microbial water quality results from two of Phnom Penh's peri-urban communities, and describes relationships between water source and treatment type, study site and storage vessel, relative to water quality guidelines. Treating water by boiling was a common practice, although the majority of residents indicated using boiling times far greater than required, which may impact adoption rates. A statistical difference is described between boiled water by source type, with boiled shallow well water having elevated E. coli levels. The only household drinking water type that met WHO guidelines most of the time was boiled rain or tank (vendor) water (56%); boiled rain or tank (vendor) water stored in a kettle, bucket/cooler or bucket with spigot met guideline values 69, 43 and 60% of the time, respectively. The highest quality water is from boiled rain or tank (vendor) water taken directly from a kettle. The findings described provide some insight on how to prioritize water options for various uses.
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Allende, Luz, María Soledad Fontanarrosa, Ayelen Murno, and Rodrigo Sinistro. "Phytoplankton functional group classifications as a tool for biomonitoring shallow lakes: a case study." Knowledge & Management of Aquatic Ecosystems, no. 420 (2019): 5. http://dx.doi.org/10.1051/kmae/2018044.
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We assessed changes in phytoplankton community structure in relation to environmental variables in an urban eutrophic shallow lake (Lake Lugano, Argentina) throughout one year following two classification systems according to the morpho-functional groups (MFG) approach and morphologically based functional groups (MBFG). We aimed to compare the different approaches and find a simple tool to biomonitor urban freshwaters regarding their phytoplankton structure. Values of transparency, nutrients and chlorophyll a concentrations confirmed the eutrophic/hypertrophic conditions of the lake. The potentially toxic Cyanobacteria Planktothrix agardhii representing MFG 5a and MBFG III was generally dominant and reached bloom densities (>62,000 ind ml−1). The multivariate analyses performed showed similar and overlapping results considering both approaches. Nutrients and transparency were the main environmental variables explaining the variance encountered. We conclude that MBFG classification was an adequate, easy-to-handle method for monitoring Lake Lugano. The functional approaches applied enabled the follow-up of potentially toxic Cyanobacteria in Lake Lugano. Further studies should include the estimation of cyanobacteria-derived toxin concentrations in water. We consider that the applicability of the MBFG approach deserves to be further explored as a promising tool for biomonitoring different types of urban water bodies.
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Schneider, Silvana Isabel, Jaqueline Ineu Golombieski, Debora Seben, Kananda Cabral Menegazzo, Arci Dirceu Wastowski, Willian Fernando de Borba, Samara Terezinha Decezaro, and Raphael Corrêa Medeiros. "Water quality in individual groundwater supply systems in Southern Brazil." Ciência e Natura 43 (June 30, 2021): e65. http://dx.doi.org/10.5902/2179460x65195.
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This study aimed to evaluate the potability of drinking water in ten municipalities of Rio Grande do Sul State, Brazil, distributed in rural and urban areas, with three different sources: springs, shallow wells, and deep wells. The water quality parameters analyzed from 2017 to 2019 were: pH, temperature, apparent and true color, turbidity, electrical conductivity, total alkalinity, total hardness, nitrate, total phosphorus, total iron, fluoride, biochemical oxygen demand, total coliforms, and Escherichia coli. A macroscopic analysis was also conducted in the surrounding of sampling points. According to the Brazilian and the WHO (World Health Organization) guidelines, some of the analyzed variables, in some sampling points, were in disagreement with the current both guidelines, which are pH, apparent color, turbidity, total iron, total coliforms, and Escherichia coli. The surveillance showed that the deeper the water is abstracted the less are natural and anthropogenic interferences in physical, chemical, and microbiological characteristics of the water; and the protection of the location where the water is abstracted improves its quality. Nonetheless, for the sampled waters it is necessary a disinfection process for posterior human consumption.
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Jin, Mengxiao, Michele Lancia, Yong Tian, Stefano Viaroli, Charles Andrews, Junguo Liu, and Chunmiao Zheng. "The Role of Aquifers in Sustaining the Sponge City Concept in Chinese High-Density Housing." Water 14, no. 6 (March 16, 2022): 929. http://dx.doi.org/10.3390/w14060929.
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Chinese cities and megacities occupy large areas with high population densities. These urban sectors have extensive impervious surfaces and import large amounts of water from pristine sources, putting pressure on the urban drainage systems during storms. To reduce flood risk and tackle water scarcity, the Chinese government promulgated the Sponge City concept: an ensemble of absorbing features, including permeable pavements and green roofs, to reduce urban runoff and increase water storage. We evaluate the benefits of merging the urban aquifer with conventional Sponge City features by simulating stormwater storage in aquifers with a groundwater model (MODFLOW) and a stormwater management model (SWMM). The urban aquifers of an ideal district, characterized by high-density housing and a flat morphology, collect and dissipate extreme rains (200 mm in 6 h) when the hydraulic conductivity of the subsoil is higher than 1·10−5 m/s, roughly corresponding to a medium productive aquifer. Economic and ecological benefits at the catchment scale are also discussed. Suitable shallow aquifers are individuated and discussed throughout China via a hydrogeological and geomorphological approach. The proposed method increases the percentage of water that can be controlled above that obtained through conventional Sponge City features.
11
Sahu, Omprakash. "Reduction of Heavy Metals from Waste Water by Wetland." International Letters of Natural Sciences 12 (March 2014): 35–43. http://dx.doi.org/10.18052/www.scipress.com/ilns.12.35.
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Constructed wetlands are artificial wastewater treatment systems consisting of shallow ponds or channels which have been planted with aquatic plants, and which rely upon natural microbial, biological, physical and chemical processes to treat wastewater. They typically have impervious clay or synthetic liners, and engineered structures to control the flow direction, liquid detention time and water level. Depending on the type of system, they may or may not contain an inert porous media such as rock, gravel or sand. Constructed wetlands have been used to treat a variety of wastewaters including urban runoff; municipal, industrial, agricultural and acid mine drainage. In this regard’s an attempted has been made to reduce the heavy metal present in waste water
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Sahu, Omprakash. "Reduction of Heavy Metals from Waste Water by Wetland." International Letters of Natural Sciences 12 (March 14, 2014): 35–43. http://dx.doi.org/10.56431/p-66qm76.
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Constructed wetlands are artificial wastewater treatment systems consisting of shallow ponds or channels which have been planted with aquatic plants, and which rely upon natural microbial, biological, physical and chemical processes to treat wastewater. They typically have impervious clay or synthetic liners, and engineered structures to control the flow direction, liquid detention time and water level. Depending on the type of system, they may or may not contain an inert porous media such as rock, gravel or sand. Constructed wetlands have been used to treat a variety of wastewaters including urban runoff; municipal, industrial, agricultural and acid mine drainage. In this regard’s an attempted has been made to reduce the heavy metal present in waste water
13
Marobhe, Nancy Jotham. "Critical review of water supply services in urban and rural areas of Tanzania." Water Policy 10, no. 1 (October 1, 2007): 57–71. http://dx.doi.org/10.2166/wp.2007.029.
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Despite several reforms in the water sector coupled with significant external financial assistance for water development projects, a large population in Tanzania faces water supply problems. This paper analyses issues and problems pertaining to urban and rural water supply services in Tanzania by citing examples from Dar es Salaam City and Singida rural district. Desk study, field visits, discussions and personal observations were used for collecting information. Water supply coverage is 73% and 53% for urban and rural areas, respectively. Only 30% of the population in Dar es Salaam is served by piped water. The unserved poorer segments of the population pay higher for water services. The water distribution systems are worn out and account for 60% of water loss. Inadequate coverage of water supply is associated with prevalence of waterborne diseases. Urban water authorities are inefficient in financial management. Water tariffs are low, ranging between US$ 0.25 and US$ 0.35/m3/month and unregistered customers exceed 110, 000. Singida rural water sources include dams, shallow and deep wells. About 70% of installed pumps are impaired owing to poor management. Rural populations use polluted sources which are purified using local seeds. Finally the paper gives recommendations for improving water supply services.
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Sun, Linhua, and Weihua Peng. "Heavy metals in shallow groundwater of the urban area in Suzhou, northern Anhui Province, China." Water Practice and Technology 9, no. 2 (June 1, 2014): 197–205. http://dx.doi.org/10.2166/wpt.2014.023.
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Urbanization and related human activities have brought bad effects to the environment, especially shallow groundwater systems in urban areas. In this study, sixty-three shallow groundwater samples in the urban area of Suzhou, northern Anhui Province, China were collected and analyzed for the concentrations of eight heavy metals (Fe, Mn, Zn, Cr, Cd, Cu, Pb and Ni). The results indicate that some of the heavy metals (Zn, Ni, Cr, Cd and Fe) are present below the international drinking water standards but more than half of the sources sampled do not meet the requirements for Mn, Cu and Pb. Quality assessment suggests that all of the samples have heavy metal pollution indices (HPI) lower than 100, implying that they can be used for drinking directly. However, the degrees of contamination (Cd) observed suggest that about one third of the samples are classified as heavily polluted. Heavy densities of population and traffic in the old quarter of the city are considered responsible for the pollution of the groundwater system in the city. Moreover, Cd, Pb, Ni and Mn are identified as metals affected by human activities, whereas Fe, Zn, Cu and Cr are considered to originate from the natural environment, based on the comparison of spatial distributions of HPI, Cd and heavy metal concentrations, as well as factor analysis.
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von Sperling, M., and J. G. B. de Andrada. "Simple wastewater treatment (UASB reactor, shallow polishing ponds, coarse rock filter) allowing compliance with different reuse criteria." Water Science and Technology 54, no. 11-12 (December 1, 2006): 199–205. http://dx.doi.org/10.2166/wst.2006.761.
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UASB reactors followed by polishing ponds comprise simple and economic wastewater treatment systems, capable of reaching very high removal efficiencies of pathogenic organisms, leading to the potential use of the effluent for unrestricted irrigation. However, for other types of reuse (urban and industrial), ponds are limited in the sense of producing effluents with high suspended solids (algae) concentrations. The work investigates a system with coarse rock filters for polishing the pond effluent. The overall performance of the system is analyzed, together with the potential for different types of reuse. The excellent results obtained (mean effluent concentrations: BOD: 27 mg/L; SS: 26 mg/L; E. coli: 450 MPN/100 mL) indicate the possibility of unrestricted use of the effluent for agriculture and restricted urban and industrial uses, according to WHO and USEPA.
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Андреев, A. Andreev, Кондратьева, and L. Kondrateva. "Complex Assessment of Underground Water Sources’ Quality in Khabarovsk City Territory." Safety in Technosphere 5, no. 4 (August 25, 2016): 30–37. http://dx.doi.org/10.12737/23759.
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In case of water bodies’ surface contamination the water supply systems based on underground sources could supply of
fresh water to the urban population with maximum guaranteed safety. In emergency the entire resource of underground
water sources is used, including shallow water intakes and individual wells. The results of the complex research for the
quality of fresh water taken from wells located in Khabarovsk city districts with different anthropogenic charge levels are
considered in this paper. For the first time the fresh water quality monitoring aimed to potential risks estimation was held
using the indicators of radon’s volumetric activity. The assessment for a seasonal variation of the fresh water quality by the
microbiological indicators and the heavy metals ions quantity has been presented.
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Chi, Nguyen Thuy Lan, Phan Dao, and Miroslav Kyncl. "Water Supply Status in Rural Areas of the Mekong Delta and Development Measures." GeoScience Engineering 64, no. 1 (March 1, 2018): 35–41. http://dx.doi.org/10.2478/gse-2018-0005.
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Abstract Rural people in the Mekong Delta (MD) use surface water from rivers and canals for daily activities; and in areas far from the canals, people use rainwater for cooking and drinking. In certain areas, people use shallow layered groundwater and deep layered groundwater from drilled wells 80m – 100m deep. The quality of water used in daily activities of rural people is almost uncontrolled. Somewhere water supply systems are used, but they have been built over many periods, certain ones for over 50 years ago, thus having a lot of damage and many deposits, causing loss of pressure and huge loss of water. The issue of repairing, replacing and installing more water supply networks in urban areas is facing lots of financial, technical difficulties.
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Brodie, I. M. "Hydrological analysis of single and dual storage systems for stormwater harvesting." Water Science and Technology 58, no. 5 (September 1, 2008): 1039–46. http://dx.doi.org/10.2166/wst.2008.469.
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As stormwater flows are intermittent, the requirement to store urban runoff is important to the design of a stormwater re-use scheme. In many urban areas, the space available to provide storage is limited and thus the need to optimise the storage volume becomes critical. This paper will highlight the advantages and disadvantages of two different approaches of providing storage: 1) a single shallow storage (0.5 m depth) in which stormwater capture and a balanced release to supply users is provided by the one unit; and 2) a dual system in which the functions of stormwater capture and supply release are provided by two separate deeper storage units (2 m depth). The comparison between the two strategies is supported by water balance modelling assessing the supply reliability and storage volume requirements for both options. Above a critical volumetric capacity, the supply yield of a dual storage system is higher than that from a single storage of equal volume mainly because of a smaller assumed footprint. The single storage exhibited greater evaporation loss and is more susceptible to algae blooms due to long water residence times. Results of the comparison provide guidance to the design of more efficient storages associated with stormwater harvesting systems.
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Martí, D., R. Carbonell, I. Flecha, I. Palomeras, J. Font-Capó, E. Vázquez-Suñé, and A. Pérez-Estaún. "High-resolution seismic characterization in an urban area: Subway tunnel construction in Barcelona, Spain." GEOPHYSICS 73, no. 2 (March 2008): B41—B50. http://dx.doi.org/10.1190/1.2832626.
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Traveltime seismic tomography used to aid subway tunnel drilling in Barcelona, Spain, provides a detailed characterization of the shallow subsurface, including a complex network of faults and dikes. We encountered many difficulties while working in this urban setting, such as cultural noise and the inability to deploy instruments along much of the tunnel trace because of the street layout. Furthermore, the shallow subsurface is highly heterogeneous (because of gas and water lines, building foundations, and the sewage system), obscuring deeper structures. We acquired seismic data using a 10-s vibroseis sweep that provided relatively good signal-to-noise (S/N) ratio. First-arrival traveltime tomography proved to be a key tool to differentiate rock vol-umes characterized by different physical properties — in particular, the contact between the weathered upper layer and the more competent rock below. We interpreted the seismic results using surface geologic observations and borehole cores. Low seismic velocities [Formula: see text] characterize the shallow part of the subsurface, representing quaternary sediments and weathered granite. Several high-velocity anomalies (up to [Formula: see text]) are interpreted as porphyritic dikes and are surrounded by low-velocity anomalies that correspond with fault systems that cut and displace the dikes. The tomographic velocity models also provide a detailed image of an important Miocene fault that intersects the tunnel trace. These results provide insights important for the drilling process.
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Song, Huina, Han Wu, Jianhua Huang, Hua Zhong, Meilin He, Mingkun Su, Gaohang Yu, Mengyuan Wang, and Jianwu Zhang. "HA-Unet: A Modified Unet Based on Hybrid Attention for Urban Water Extraction in SAR Images." Electronics 11, no. 22 (November 17, 2022): 3787. http://dx.doi.org/10.3390/electronics11223787.
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Urban water plays a significant role in the urban ecosystem, but urban water extraction is still a challenging task in automatic interpretation of synthetic aperture radar (SAR) images. The influence of radar shadows and strong scatters in urban areas may lead to misclassification in urban water extraction. Nevertheless, the local features captured by convolutional layers in Convolutional Neural Networks (CNNs) are generally redundant and cannot make effective use of global information to guide the prediction of water pixels. To effectively emphasize the identifiable water characteristics and fully exploit the global information of SAR images, a modified Unet based on hybrid attention mechanism is proposed to improve the performance of urban water extraction in this paper. Considering the feature extraction ability and the global modeling capability in SAR image segmentation, the Channel and Spatial Attention Module (CSAM) and the Multi-head Self-Attention Block (MSAB) are both introduced into the proposed Hybrid Attention Unet (HA-Unet). In this work, Resnet50 is adopted as the backbone of HA-Unet to extract multi-level features of SAR images. During the feature extraction process, CSAM based on local attention is adopted to enhance the meaningful water features and ignore unnecessary features adaptively in feature maps of two shallow layers. In the last two layers of the backbone, MSAB is introduced to capture the global information of SAR images to generate global attention. In addition, two global attention maps generated by MSAB are aggregated together to reconstruct the spatial feature relationship of SAR images from high-resolution feature maps. The experimental results on Sentinel-1A SAR images show that the proposed urban water extraction method has a strong ability to extract water bodies in the complex urban areas. The ablation experiment and visualization results vividly indicate that both CSAM and MSAB contribute significantly to extracting urban water accurately and effectively.
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von Sperling, M., and L. C. A. M. Mascarenhas. "Performance of very shallow ponds treating effluents from UASB reactors." Water Science and Technology 51, no. 12 (June 1, 2005): 83–90. http://dx.doi.org/10.2166/wst.2005.0432.
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Polishing ponds are units conceived for the post-treatment of the effluents from anaerobic reactors, are designed as maturation ponds, and aim at a further removal of organic matter and a high removal of pathogenic organisms. The paper investigates the performance of four very shallow (H = 0.40 m) polishing ponds in series, with very low detention times (1.4–2.5 days in each pond), treating anaerobic effluent from the city of Belo Horizonte, Brazil. The system was able to achieve excellent results in terms of BOD and E. coli removal, and good results in terms of ammonia removal, allowing compliance with European standards for urban wastewater and WHO guidelines for unrestricted irrigation. The paper presents the values of BOD and E. coli removal coefficients, which were much higher than those found in conventional pond systems. No statistically significant difference was found in the effluent E. coli concentrations from a pond with low depth and low detention time, and another pond in parallel, with double the depth and approximately double the detention time. The results endorse the applicability of the system composed by UASB reactors followed by very shallow ponds in series, with low detention times.
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Pilone, Forrest Gage, Pablo A. Garcia-Chevesich, and John E. McCray. "Urban Drool Water Quality in Denver, Colorado: Pollutant Occurrences and Sources in Dry-Weather Flows." Water 13, no. 23 (December 4, 2021): 3436. http://dx.doi.org/10.3390/w13233436.
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Dry-weather flows in urban channels and streams, often termed “urban drool”, represent an important source of urban surface water impairment, particularly in semi-arid environments. Urban drool is a combination of year-round flows in urban channels, natural streams, and storm-sewer systems (runoff from irrigation return flow, car washes, street cleaning, leakage of groundwater or wastewater into streams or storm sewers, etc.). The purpose of this study was to better understand the extent and sources of urban drool pollution in Denver, Colorado by identifying relationships between urban catchment characteristics and pollutants. Water-quality samples were taken throughout Denver at urban drainage points that were representative of a variety of urban characteristics. Samples were analyzed for total suspended solids (TSS), coliforms, Escherichia Coli (E. coli), nutrients (nitrate, phosphorus, and potassium), dissolved and total organic carbon, and dissolved and total recoverable metals. Results from this study were as follows: (1) most contaminants (nitrate, phosphorus, arsenic, iron, manganese, nickel, selenium, and zinc) were concluded to be primarily loaded from shallow groundwater; (2) anthropogenic effects likely exacerbated groundwater pollutant concentrations and contributions to surface water; (3) nitrate, nickel, and manganese may be partially contributed by industrial inputs; (4) medical marijuana cultivation sites were identified as a potential source of nutrient and zinc pollution; (5) E. coli was a ubiquitous contaminant in all urban waterways; (6) erosion of contaminated urban soils, presumably from construction, was found to significantly increase concentrations of TSS, total phosphorus, and total metals. Increasing urbanization and predicted drier climates suggest that dry-weather flows will become more important to manage; the results from this study provide insight on dry-weather water quality management for the City and County of Denver.
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Sikdar, P. K., and P. Sahu. "Understanding wetland sub-surface hydrology using geologic and isotopic signatures." Hydrology and Earth System Sciences Discussions 6, no. 2 (April 8, 2009): 3143–73. http://dx.doi.org/10.5194/hessd-6-3143-2009.
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Abstract. This paper attempts to utilize hydrogeoloy and isotope composition of groundwater to understand the present hydrological processes prevalent in a freshwater wetland, source of wetland groundwater, surface water/groundwater interaction and mixing of groundwater of various depth zones in the aquifer. This study considers East Calcutta Wetlands (ECW) – a freshwater peri-urban inland wetland ecosystem located at the lower part of the deltaic alluvial plain of South Bengal Basin and east of Kolkata city. This wetland is well known over the world for its resource recovery systems, developed by local people through ages, using wastewater from the city. Geological investigations reveal that the sub-surface geology is completely blanketed by the Quaternary sediments comprising a succession of silty clay, sand of various grades and sand mixed with occasional gravels and thin intercalations of silty clay. Aquifer within the depths of 80 m to 120 m has the maximum potential to supply water. Groundwater mainly flows from east to west and is being over-extracted to the tune of 65×103 m3/day. δ18O and δD values of shallow and deep groundwater are similar indicating resemblance in hydrostratigraphy and climate of the recharge areas. Groundwater originates mainly from monsoonal rain with some evaporation prior to or during infiltration and partly from bottom of ponds, canals and infiltration of groundwater withdrawn for irrigation. Relatively high tritium content of the shallow groundwater indicates local recharge, while the deeper groundwater with very low tritium is recharged mainly from distant areas. At places the deeper aquifer has relatively high tritium, indicating mixing of groundwater of shallow and deep aquifers. Metals such as copper, lead, arsenic, cadmium, aluminum, nickel and chromium are also present in groundwater of various depths. Therefore, aquifers of wetland and surrounding urban areas which are heavily dependent on groundwater are vulnerable to pollution and hence surface water-groundwater interaction should be minimized by regulating tubewell operation time, introducing treated surface water supply system and artificially recharging the aquifer.
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Sikdar, P. K., and P. Sahu. "Understanding wetland sub-surface hydrology using geologic and isotopic signatures." Hydrology and Earth System Sciences 13, no. 7 (July 28, 2009): 1313–23. http://dx.doi.org/10.5194/hess-13-1313-2009.
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Abstract. This paper attempts to utilize hydrogeology and isotope composition of groundwater to understand the present hydrological processes prevalent in a freshwater wetland, source of wetland groundwater, surface water/groundwater interaction and mixing of groundwater of various depth zones in the aquifer. This study considers East Calcutta Wetlands (ECW) – a freshwater peri-urban inland wetland ecosystem located at the lower part of the deltaic alluvial plain of South Bengal Basin and east of Kolkata city. This wetland is well known over the world for its resource recovery systems, developed by local people through ages, using wastewater of the city. Geological investigations reveal that the sub-surface geology is completely blanketed by the Quaternary sediments comprising a succession of silty clay, sand of various grades and sand mixed with occasional gravels and thin intercalations of silty clay. At few places the top silty clay layer is absent due to scouring action of past channels. In these areas sand is present throughout the geological column and the areas are vulnerable to groundwater pollution. Groundwater mainly flows from east to west and is being over-extracted to the tune of 65×103 m3/day. δ18O and δD values of shallow and deep groundwater are similar indicating resemblance in hydrostratigraphy and climate of the recharge areas. Groundwater originates mainly from monsoonal rain with some evaporation prior to or during infiltration and partly from bottom of ponds, canals and infiltration of groundwater withdrawn for irrigation. Relatively high tritium content of the shallow groundwater indicates local recharge, while the deep groundwater with very low tritium is recharged mainly from distant areas. At places the deep aquifer has relatively high tritium, indicating mixing of groundwater of shallow and deep aquifers. Metals such as copper, lead, arsenic, cadmium, aluminium, nickel and chromium are also present in groundwater of various depths. Therefore, aquifers of wetland and surrounding urban areas which are heavily dependent on groundwater are vulnerable to pollution. In the area south of ECW isotope data indicates no interaction between shallow and deep aquifer and hence this area may be a better location to treat sewage water than within ECW. To reduce the threat of pollution in ECW's aquifer, surface water-groundwater interaction should be minimized by regulating tubewell operation time, introducing treated surface water supply system and artificial recharging of the aquifer.
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Ibrahim, Nilam Ismi, Petrick Th Berhitu, and Ferad Puturuhu. "EVALUASI SISTEM DRAINASE DALAM UPAYA PENANGGULANGAN BANJIR (STUDI KASUS KELURAHAN HONIPOPU KOTA AMBON)." JURNAL GEOGRAFI Geografi dan Pengajarannya 20, no. 2 (December 30, 2022): 131–43. http://dx.doi.org/10.26740/jggp.v20n2.p131-143.
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Urban drainage systems serve the disposal of excess water in a city by draining it through the soil surface or passing below the ground surface, to be discharged into rivers, lakes and the sea. The excess water can be in the form of rainwater, domestic wastewater and industrial wastewater. Therefore, in order to prevent flooding in urban areas, an urban drainage system must be integrated with sanitation, garbage, city flood control and also the state of the surrounding area. The objectives of this research are 1) to identify the drainage system that always causes flooding in Honipopu Village, Ambon City; 2) Determine the direction of the right drainage system in an effort to overcome flooding in Honipopu Village, Ambon City. Data collection methods used in this study include: observation, interview techniques, agency surveys, and documentation. Analysis of the data used is an analysis of the basic physical conditions of the research area, including slope, hydrology, nalysis of the data used is an analysis of the basic physical conditions of the research area, including slope, hydrology, rainfall conditions and land use. Drainage conditions in Honipopu Village are poor due to very high sedimentation and waste water discharge causing drainage to become shallow and also to inadequate drainage system. The direction of the drainage system in an effort to cope with flooding in the Honipopu village is the rehabilitation and normalization of drainage strategies.
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Afonso, Maria José, Liliana Freitas, José Manuel Marques, Paula M. Carreira, Alcides J. S. C. Pereira, Fernando Rocha, and Helder I. Chaminé. "Urban Groundwater Processes and Anthropogenic Interactions (Porto Region, NW Portugal)." Water 12, no. 10 (October 9, 2020): 2797. http://dx.doi.org/10.3390/w12102797.
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Groundwater in fissured rocks is one of the most important reserves of available fresh water, and urbanization applies an extremely complex pressure which puts this natural resource at risk. Two-thirds of Portugal is composed of fissured aquifers. In this context, the Porto urban region is the second biggest metropolitan area in mainland Portugal. In this study, a multidisciplinary approach was developed, using hydrogeological GIS-based mapping and modeling, combining hydrogeochemical, isotopic, and hydrodynamical data. In addition, an urban infiltration potential index (IPI-Urban) was outlined with the combination of several thematic layers. Hydrogeochemical signatures are mainly Cl-Na to Cl-SO4-Na, being dependent on the geographic proximity of this region to the ocean, and on anthropogenic and agricultural contamination processes, namely fertilizers, sewage, as well as animal and human wastes. Isotopic signatures characterize a meteoric origin for groundwater, with shallow flow paths and short residence times. Pumping tests revealed a semi- to confined system, with low long-term well capacities (<1 L/s), low transmissivities (<4 m2/day), and low storage coefficients (<10−2). The IPI-Urban index showed a low groundwater infiltration potential, which was enhanced by urban hydraulic and sanitation features. This study assessed the major hydrogeological processes and their dynamics, therefore, contributing to a better knowledge of sustainable urban groundwater systems in fractured media.
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Cui, Yunsong, Qiuhua Liang, Gang Wang, Jiaheng Zhao, Jinchun Hu, Yuehua Wang, and Xilin Xia. "Simulation of Hydraulic Structures in 2D High-Resolution Urban Flood Modeling." Water 11, no. 10 (October 15, 2019): 2139. http://dx.doi.org/10.3390/w11102139.
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Urban flooding as a result of inadequate drainage capacity, failure of flood defenses, etc. is usually featured with highly transient hydrodynamics. Reliable and efficient prediction and forecasting of these urban flash floods is still a great technical challenge. Meanwhile, in urban environments, the flooding hydrodynamics and process may be influenced by flow regulation and flood protection hydraulic infrastructure systems, such as sluice gates, which should be effectively taken into account in an urban flood model. However, direct simulation of hydraulic structures is not a current practice in 2D urban flood modeling. This work aims to develop a robust numerical approach to directly simulate the effects of gate structures in a 2D high-resolution urban flood model. A new modeling component is developed and fully coupled to a finite volume Godunov-type shock-capturing shallow water model, to directly simulate the highly transient flood waves through hydraulic structures. Different coupling approaches, i.e., flux term coupling and source term coupling, are implemented and compared. A numerical experiment conducted for an analytical dam-break test indicates that the flux term coupling approach may lead to more accurate results, with the calculated RMSE against water level 28%–38% less than that produced by the source term coupling approach. The flux term coupling approach is therefore adopted to improve the current urban flood model, and it is further tested by reproducing the laboratory experiments of flood routing in a flume with partially open sluice gates, conducted in the hydraulic laboratory at the Zhejiang Institute of Hydraulics and Estuary, China. The numerical results are compared favorably with experimental measurements, with a maximum RMSE of 0.0851 for all the individual tests. The satisfactory results demonstrate that the flood model implemented with the flux coupling approach is able to accurately simulate the flow through hydraulic structures, with enhanced predictive capability for urban flood modeling.
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Singh, Prateek Kumar, Xiaonan Tang, and Hamidreza Rahimi. "Large-Eddy Simulation of Compound Channels with Staged Floodplains: Flow Interactions and Turbulent Structures." Water 15, no. 5 (March 3, 2023): 983. http://dx.doi.org/10.3390/w15050983.
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Numerous sources of overtopping and flood events suggest different cross-sectional land characteristics of the river and urban river water systems. Multiple stages of floodplains in compound channels are viable in urban areas to facilitate bank slope stability and a higher discharge capacity for different flow rates. The complexity of the contiguous floodplains’ compound channel flows manifold with the interactive geometry and roughness of the surrounding floodplains. In the present study, a large-eddy simulation study is undertaken to investigate the turbulent structure of open channels with multiple-stage floodplains. The validation uses experimental data collected at individual contiguous multiple-stage floodplains for three depth ratios from shallow to deep flow regimes. The wall-modelled large eddy simulations were validated with the depth-averaged velocity, primary velocity and secondary currents. Furthermore, the impact of the multiple-stage floodplains on the instantaneous flow fields and large-scale vortical structures is predicted herein. It was found that vortical structures affect the distribution of the momentum exchange over multiple-stage floodplains.
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Fernández-Pato, Javier, and Pilar García-Navarro. "An Efficient GPU Implementation of a Coupled Overland-Sewer Hydraulic Model with Pollutant Transport." Hydrology 8, no. 4 (September 30, 2021): 146. http://dx.doi.org/10.3390/hydrology8040146.
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Numerical simulation of flows that consider interaction between overland and drainage networks has become a practical tool to prevent and mitigate flood situations in urban environments, especially when dealing with intense storm events, where the limited capacity of the sewer systems can be a trigger for flooding. Additionally, in order to prevent any kind of pollutant dispersion through the drainage network, it is very interesting to have a certain monitorization or control over the quality of the water that flows in both domains. In this sense, the addition of a pollutant transport component to both surface and sewer hydraulic models would benefit the global analysis of the combined water flow. On the other hand, when considering a realistic large domain with complex topography or streets structure, a fine spatial discretization is mandatory. Hence the number of grid cells is usually very large and, therefore, it is necessary to use parallelization techniques for the calculation, the use of Graphic Processing Units (GPU) being one of the most efficient due to the leveraging of thousands of processors within a single device. In this work, an efficient GPU-based 2D shallow water flow solver (RiverFlow2D-GPU) is fully coupled with EPA’s Storm Water Management Model (SWMM). Both models are able to develop a transient water quality analysis taking into account several pollutants. The coupled model, referred to as RiverFlow2D-GPU UD (Urban Drainge) is applied to three real-world cases, covering the most common hydraulic situations in urban hydrology/hydraulics. A UK Environmental Agency test case is used as model validation, showing a good agreement between RiverFlow2D-GPU UD and the rest of the numerical models considered. The efficiency of the model is proven in two more complex domains, leading to a >100x faster simulations compared with the traditional CPU computation.
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Fan, Chia-Cheng, Shu-Cheng Li, and Jin-Zong Lu. "Modeling the Effect of High Soil Moisture on the Wind Resistance of Urban Trees." Forests 13, no. 11 (November 9, 2022): 1875. http://dx.doi.org/10.3390/f13111875.
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In urban areas, typhoons frequently cause the tilting and uprooting of trees, resulting in damage to city infrastructure. During periods of intense rainfall, at shallow soil depths, soil water content is typically high, reducing the anchoring resistance of tree roots in the soil. Tree root systems play an important role in providing anchoring resistance against severe winds during typhoons. In this study, we examined the influence of high soil saturation on the turning resistance of trees by conducting winching tests on three tree species found in urban areas. In highly saturated soils, the maximum resisting moment of camphor trees (Cinnamomum camphora (L.) J. Presl.) is 35–50% lower than in soils with low saturation levels. A tree’s maximum resisting moment (TMmax) exhibits a linearly positive relationship with its diameter at breast height (DBH) in near-saturated soil conditions. The ratio of TMmax values to DBH in near-saturated soils is noticeably lower than in low-moisture soils. Our research establishes a relationship between the DBH of trees and the strength of the wind that they can resist during typhoons, as measured on the Beaufort scale.
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Abdalla, Elhadi Mohsen Hassan, Ingrid Selseth, Tone Merete Muthanna, Herman Helness, Knut Alfredsen, Terje Gaarden, and Edvard Sivertsen. "Hydrological performance of lined permeable pavements in Norway." Blue-Green Systems 3, no. 1 (January 1, 2021): 107–18. http://dx.doi.org/10.2166/bgs.2021.009.
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Abstract Lined permeable pavements (LPPs) are types of sustainable urban stormwater systems (SUDs) that are suitable for locations with low infiltration capacity or shallow groundwater levels. This study evaluated the hydrological performance of an LPP system in Norway using common detention indicators and flow duration curves (FDCs). Two hydrological models, the Storm Water Management Model (SWMM)-LID module and a reservoir model, were applied to simulate continuous outflows from the LPP system to plot the FDCs. The sensitivity of the parameters of the SWMM-LID module was assessed using the generalized likelihood uncertainty estimation methodology. The LPP system was found to detain the flow effectively based on the median values of the detention indicators (peak reduction = 89%, peak delay = 40 min, centroid delay = 45 min, T50-delay = 86 min). However, these indicators are found to be sensitive to the amount of precipitation and initial conditions. The reservoir model developed in this study was found to yield more accurate simulations (higher NSE) than the SWMM-LID module, and it can be considered a suitable design tool for LPP systems. The FDC offers an informative method to demonstrate the hydrological performance of LPP systems for stormwater engineers and decision-makers.
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Sailer, Eleonora, David M. G. Taborda, Lidija Zdravkovic, and David M. Potts. "Assessing the impact of vertical heat exchangers on the response of a retaining wall." E3S Web of Conferences 92 (2019): 16001. http://dx.doi.org/10.1051/e3sconf/20199216001.
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Shallow geothermal energy systems, e.g. borehole heat exchangers or thermo-active structures, provide sustainable space heating and cooling by exchanging heat with the ground. When installed within densely built urban environments, the thermo-hydro-mechanical (THM) interactions occurring due to changes in ground temperature, such as soil deformation and development of excess pore water pressures, may affect the mechanical behaviour of adjacent underground structures. This paper investigates the effects of vertical heat exchangers installed near a deep basement by performing fully coupled THM finite element analyses using the Imperial College Finite Element Program. Different heat exchanger configurations are considered and their influence on the response of the basement wall is assessed in two-dimensional plane strain analyses, where different methods of modelling the heat sources in this type of analysis are employed to evaluate their effect on the temperature field and the non-isothermal soil response.
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Rech, Aline, Elisa Pacheco, Jakcemara Caprario, Julio Cesar Rech, and Alexandra Rodrigues Finotti. "Low-Impact Development (LID) in Coastal Watersheds: Infiltration Swale Pollutant Transfer in Transitional Tropical/Subtropical Climates." Water 14, no. 2 (January 14, 2022): 238. http://dx.doi.org/10.3390/w14020238.
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The control of runoff pollution is one of the advantages of low-impact development (LID) or sustainable drainage systems (SUDs), such as infiltration swales. Coastal areas may have characteristics that make the implementation of drainage systems difficult, such as sandy soils, shallow aquifers and flat terrains. The presence of contaminants was investigated through sampling and analysis of runoff, soil, and groundwater from a coastal region served by an infiltration swale located in southern Brazil. The swale proved to be very efficient in controlling the site’s urban drainage volumes even under intense tropical rainfall. Contaminants of Cd, Cu, Pb, Zn, Cr, Fe, Mn and Ni were identified at concentrations above the Brazilian regulatory limit (BRL) in both runoff and groundwater. Soil concentrations were low and within the regulatory limits, except for Cd. The soil was predominantly sandy, with neutral pH and low ionic exchange capacity, characteristic of coastal regions and not very suitable for contaminant retention. Thus, this kind of structure requires improvements for its use in similar environments, such as the use of adsorbents in soil swale to increase its retention capacity.
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Stephansen, Diana A., Carlos A. Arias, Hans Brix, Morten L. Fejerskov, and Asbjørn H. Nielsen. "Relationship between Polycyclic Aromatic Hydrocarbons in Sediments and Invertebrates of Natural and Artificial Stormwater Retention Ponds." Water 12, no. 7 (July 16, 2020): 2020. http://dx.doi.org/10.3390/w12072020.
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Sediments and invertebrates were sampled from 9 stormwater retention ponds (SWRPs) and 11 natural, shallow lakes in Denmark. Samples were analyzed for 13 polycyclic aromatic hydrocarbons (PAHs). The SWRPs received urban and highway runoff from various types of drainage areas and the lakes were located in areas of various land uses. Comparing PAHs in the sediments of the SWRPs and the lakes, it was found that levels of total PAH were similar in the two aquatic systems, with median values of 0.94 and 0.63 mg·(kg·DM)−1 in sediments of SWRPs and lakes, respectively. However, the SWRP sediments tended to have higher concentrations of high-molecular-weight PAHs than the lakes. A similar pattern was seen for PAHs accumulated in invertebrates where the median of total PAH was 2.8 and 2.1 mg·(kg·DM)−1 for SWRPs and lakes, respectively. Principal component analysis on the PAH distribution in the sediments and invertebrates showed that ponds receiving highway runoff clustered with lakes in forests and farmland. The same was the case for some of the ponds receiving runoff from residential areas. Overall, results showed that sediment PAH levels in all SWRPs receiving runoff from highways were similar to the levels found in some of the investigated natural, shallow lakes, as were the sediment PAH levels from some of the residential SWRPs. Furthermore, there was no systematic trend that one type of water body exceeded environmental quality standards (EQS) values more often than others. Together this indicates that at least some SWRPs can sustain an invertebrate ecosystem without the organisms experiencing higher bioaccumulation of PAHs then what is the case in shallow lakes of the same region.
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Walters, Stuart, V. Thomas, Karen Midden, and John Groninger. "Autumn Production of Romaine Lettuce on an Extensive Green Roof." Journal of Living Architecture 10, no. 1 (2023): 13–25. http://dx.doi.org/10.46534/jliv.2023.10.01.013.
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Extensive green roofs provide a significant amount of potential available space to expand urban agriculture. Successful crop production in this type of growing system requires growers to overcome temperature extremes, as well as drought conditions and low fertility associated with a shallow and porous rooting substrate. Four cultivars of Romaine lettuce (Lactuca sativa) that included ‘Outredgeous’, 'Parris Island Cos', 'Rouge d'Hiver', and 'Rubens Baby', were grown to maturity in an 8 cm deep expanded lightweight clay substrate on an extensive green roof during the autumn production seasons of 2012 and 2013. Fast and slow release fertilizer regimes popular with growers and a no fertilizer control were provided along with supplemental water via drip irrigation as needed. Chlorophyll content, as measured by a SPAD meter, provided a useful indicator of crop plant vigor and overall plant productivity. Abnormally cold growing conditions during the critical maturation period in autumn 2013 resulted in lower yields compared to 2012. Results indicated that lettuce productivity was improved by the addition of fertilizers, with the fast release providing the greatest growth and productivity. These results demonstrate the feasibility of producing a nutritious and popular autumn crop on an extensive green roof suitable for local urban food systems. However, this research also highlights the vulnerabilities of this system to weather. Utility of green infrastructure for teaching urban agriculture and plant biology is also discussed.
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Al-Kindi, Khalifa M., Abdullah F. Alqurashi, Abdullah Al-Ghafri, and Dennis Power. "Assessing the Impact of Land Use and Land Cover Changes on Aflaj Systems over a 36-Year Period." Remote Sensing 15, no. 7 (March 27, 2023): 1787. http://dx.doi.org/10.3390/rs15071787.
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The aflaj systems represent unique irrigation technologies that have been implemented in the Sultanate of Oman. This innovative system, referred to as “falaj” in the singular form, is composed of a sophisticated network of underground tunnels and open-air channels designed to access shallow subterranean water tables, thereby providing water for residential and agricultural use. The aflaj systems have played a significant role in supporting sustainable water resource management in arid and semiarid regions, making a notable contribution to the socioeconomic development of the country. The alteration of land use and land cover (LULC) in arid and semiarid regions can have significant consequences for hydrological systems, affecting the ability of local ecosystems to manage fresh surface and groundwater resources. These changes are often caused by both natural and anthropogenic factors. To investigate the impact of LULC changes on aflaj systems in the northern part of Oman, we utilized satellite imagery, aflaj data, and spatial analytical and image processing techniques within the framework of geographic information systems (GIS) and remote sensing. In the first part of the study, we quantified the changes in LULC and their impact on aflaj systems in seven cities in Oman due to urban expansion. In the second part, we evaluated the effect of LULC on groundwater for four major aflaj between 1985 and 2021. The study area was divided into four primary LULC classifications: vegetation, bodies of water, metropolitan areas, and bare soil. The classification maps demonstrated a high overall accuracy of 90% to 95%, indicating satisfactory performance. Our results revealed a significant reduction in vegetation areas between 1985 and 2021, primarily shifting from bare soil (BS) to urban areas (UAs) and from vegetation cover (VC) to BS, due to the reduction of groundwater resources. Over the four study periods (1985–1990, 1990–2000, 2000–2013, and 2013–2021), the percentages of the total area of Falaj Al-Muyasser, Falaj Daris, Falaj Al-Maliki, and Falaj Al-Khatmeen that transformed from agricultural lands to UAs were 40%, 39%, 32%, and 8%, respectively. Our study highlights the need for appropriate land management and planning to ensure the most effective solutions are utilized to meet social and economic sustainability requirements. In conclusion, our study presents a comprehensive analysis of LULC changes and their impact on aflaj systems over a 36-year period, providing new insights into the potential effects of LULC changes on groundwater resources and offering a basis for informed decision making on land management in arid and semiarid areas.
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TIKKANEN, MATTI, ATTE KORHOLA, HEIKKI SEPPÄ, and JUHANI VIRKANEN. "A long-term record of human impacts on an urban ecosystem in the sediments of Töölönlahti Bay in Helsinki, Finland." Environmental Conservation 24, no. 4 (December 1997): 326–37. http://dx.doi.org/10.1017/s037689299700043x.
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Ecological impacts of urbanization are receiving increasing scientific attention, yet few data sets permit long-term effects on terrestrial and aquatic ecosystems to be assessed. Töölönlahti Bay, in the centre of Helsinki, Finland, provided on opportunity to characterize recent human impacts especially by means of chemical and biostratigraphical analyses of a sediment core. Periods of coniferous forest, forest clearance, urbanization and the development of parks, can be distinguished in the pollen record of the core. Palynological diversity was highest before the forest clearance at the turn of the century. The character of the sediment and the water have changed substantially in response to rapid population growth, the construction of sewage systems and building within the catchment of the bay. This is reflected in marked increases in organic matter, phosphorus and heavy metal (Cd, Cu, Ni, Zn and Pb) concentrations between 1890 and 1960, accompanied by a rapid increase in diatom species indicative of eutrophication and a decline in diatom species diversity.Since the cessation of waste-water disposal in the 1960s, concentrations of a number of pollutants have declined and water quality has gradually improved, but conditions are still affected by internal and atmospheric loadings. As a consequence of land uplift (2 mm per year) and the rapid sedimentation rate (6 mm per year), the volume of the bay is decreasing. Within 200 years, the shallow bay, which is skirted by extensive parks and famous cultural buildings such as the Finlandia and the Opera Houses, will fill with sediment unless it is dredged.
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Goodman, Joel H. "SMALL HELIOSTATS CSP SYSTEMS ON LONG-SPAN HANGING ROOFS." Journal of Green Building 14, no. 2 (March 2019): 219–42. http://dx.doi.org/10.3992/1943-4618.14.2.219.
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Building Integrated Concentrating Solar Power (BI-CSP) schematic studies with small scale exterior two-axis tracking heliostats anchored on and semi-shading long span hanging roofs with elevated receiver(s) are presented for populated urban and rural locations. Hanging roofs (inverted shallow dome shape) with two-way structural cables and mostly square infill prefabricated slabs/panels supported from a perimeter horizontal circular donut shape rim-girder-platform without a center tension ring studies are for comparing to radial cable structural configurations with a center tension ring. Cable gap grouting between slabs/panels form a pre-tensioned inverted shell structure after temporary weights are removed. Securing vertical heliostat posts studies include: three vertical bolts cast in grout gap two-way cables intersections for three point adjustment of horizontal post base plates; and one-axis adjustable manufactured post brackets bolted to sloped roof surfaces at holes cast in the gaps/slabs. A main case study schematic is around a 30m/100ft diameter hanging roof with a 0.07 sag/diameter ratio with around 271 1m2 heliostats for 230kWt solar thermal steam or air to around 300degC/572degF building integrated thermal energy storage (molten salt, firebricks, etc.) and applications (water purification, cooling, industrial process heat, etc.). A BI-CSP hanging roofs R&D project proposal is outlined: with a circular roof study diameter range of around 25m/82ft–200m/656ft diameter for comparing two-way and radial cable structural configurations for distributed steam stations and a wide range of application temperatures.
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Contreras, María Teresa, and Cristián Escauriaza. "Modeling the effects of sediment concentration on the propagation of flash floods in an Andean watershed." Natural Hazards and Earth System Sciences 20, no. 1 (January 20, 2020): 221–41. http://dx.doi.org/10.5194/nhess-20-221-2020.
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Abstract. Rain-induced flash floods are common events in regions near mountain ranges. In peri-urban areas near the Andes the combined effects of the changing climate and El Niño–Southern Oscillation (ENSO) have resulted in an alarming proximity of populated areas to flood-prone streams, increasing the risk for cities and infrastructure. Simulations of rapid floods in these watersheds are particularly challenging, due to the complex morphology, the insufficient hydrometeorological data, and the uncertainty posed by the variability of sediment concentration. High concentrations produced by hillslope erosion and rilling by the overland flow in areas with steep slopes and low vegetational covering can significantly change the dynamics of the flow as the flood propagates in the channel. In this investigation, we develop a two-dimensional finite-volume numerical model of the nonlinear shallow water equations coupled with the mass conservation of sediment to study the effects of different densities, which include a modified version of the quadratic stress model to quantify the changes in the flow rheology. We carry out simulations to evaluate the effects of the sediment concentration on the floods in the Quebrada de Ramón watershed, a peri-urban Andean basin in central Chile. We simulate a confluence and a total length of the channel of 10.4 km, with the same water hydrographs and different combinations of sediment concentrations in the tributaries. Our results show that the sediment concentration has strong impacts on flow velocities and water depths. Compared to clear-water flow, the wave-front velocity slows down more than 70 % for floods with a volumetric concentration of 60 % and the total flooded area is 36 % larger when the sediment concentration is equal to 20 %. The maximum flow momentum at cross sections in the urban area increases 14.5 % on average when the mean concentration along the main channel changes from 30 % to 44 %. Simulations also show that other variables such as the arrival time of the peak flow and the shape of the hydrograph at different locations along the channel are not significantly affected by the sediment concentration and depend mostly on the steep channel morphology. Through this work we provide a framework for future studies aimed at improving hazard assessment, urban planning, and early warning systems in urban areas near mountain streams with limited data and affected by rapid flood events.
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Rong, Youtong, Paul Bates, and Jeffrey Neal. "An improved subgrid channel model with upwind-form artificial diffusion for river hydrodynamics and floodplain inundation simulation." Geoscientific Model Development 16, no. 11 (June 13, 2023): 3291–311. http://dx.doi.org/10.5194/gmd-16-3291-2023.
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Abstract. An accurate estimation of river channel conveyance capacity and the water exchange at the river–floodplain interfaces is pivotal for flood modelling. However, in large-scale models limited grid resolution often means that small-scale river channel features cannot be well-represented in traditional 1D and 2D schemes. As a result instability over river and floodplain boundaries can occur, and flow connectivity, which has a strong control on the floodplain hydraulics, is not well-approximated. A subgrid channel (SGC) model based on the local inertial form of the shallow water equations, which allows utilization of approximated subgrid-scale bathymetric information while performing very efficient computations, has been proposed as a solution, and it has been widely applied to calculate the wetting and drying dynamics in river–floodplain systems at regional scales. Unfortunately, SGC approaches to date have not included the latest developments in numerical solutions of the local inertial equations, and the original solution scheme was reported to suffer from numerical instability in low-friction regions such as urban areas. In this paper, for the first time, we implement a newly developed diffusion and explicit adaptive weighting factor in the SGC model. Adaptive artificial diffusion is explicitly included in the form of an upwind solution scheme based on the local flow status to improve the numerical flux estimation. A structured sequence of numerical experiments is performed, and the results confirm that the new SGC model improved the model performance in terms of water level and inundation extent, especially in urban areas where the Manning parameter is less than 0.03 m-1/3 s. By not compromising computational efficiency, this improved SGC model is a compelling alternative for river–floodplain modelling, particularly in large-scale applications.
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Bockhorn, Britta, Knud Erik Strøyberg Klint, Marina Bergen Jensen, and Ingelise Møller. "Use of geological mapping tools to improve the hydraulic performance of SuDS." Water Science and Technology 71, no. 10 (March 18, 2015): 1492–99. http://dx.doi.org/10.2166/wst.2015.125.
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Most cities in Denmark are situated on low permeable clay rich deposits. These sediments are of glacial origin and range among the most heterogeneous, with hydraulic conductivities spanning several orders of magnitude. This heterogeneity has obvious consequences for the sizing of sustainable urban drainage systems (SuDS). We have tested methods to reveal geological heterogeneity at field scale to identify the most suitable sites for the placement of infiltration elements and to minimize their required size. We assessed the geological heterogeneity of a clay till plain in Eastern Jutland, Denmark measuring the shallow subsurface resistivity with a geoelectrical multi-electrode system. To confirm the resistivity data we conducted a spear auger mapping. The exposed sediments ranged from clay tills over sandy clay tills to sandy tills and correspond well to the geoelectrical data. To verify the value of geological information for placement of infiltration elements we carried out a number of infiltration tests on geologically different areas across the field, and we observed infiltration rates two times higher in the sandy till area than in the clay till area, thus demonstrating that the hydraulic performance of SuDS can be increased considerably and oversizing avoided if field geological heterogeneity is revealed before placing SuDS.
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Ramachandran, Rakhee, Yadira Bajón Fernández, Ian Truckell, Carlos Constantino, Richard Casselden, Paul Leinster, and Mónica Rivas Casado. "Accuracy Assessment of Surveying Strategies for the Characterization of Microtopographic Features That Influence Surface Water Flooding." Remote Sensing 15, no. 7 (April 2, 2023): 1912. http://dx.doi.org/10.3390/rs15071912.
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With the increase in rainfall intensity, population, and urbanised areas, surface water flooding (SWF) is an increasing concern impacting properties, businesses, and human lives. Previous studies have shown that microtopography significantly influences flow paths, flow direction, and velocity, impacting flood extent and depth, particularly for the shallow flow associated with urban SWF. This study compares two survey strategies commonly used by flood practitioners, S1 (using Unmanned Aerial Systems-based RGB data) and S2 (using manned aircraft with LiDAR scanners), to develop guidelines on where to use each strategy to better characterise microtopography for a range of flood features. The difference between S1 and S2 in elevation and their accuracies were assessed using both traditional and robust statistical measures. The results showed that the difference in elevation between S1 and S2 varies between 11 cm and 37 cm on different land use and microtopographic flood features. Similarly, the accuracy of S1 ranges between 3 cm and 70 cm, and the accuracy of S2 ranges between 3.8 cm and 30.3 cm on different microtopographic flood features. Thus, this study suggests that the flood features of interest in any given flood study would be key to select the most suitable survey strategy. A decision framework was developed to inform data collection and integration of the two surveying strategies to better characterise microtopographic features. The findings from this study will help improve the microtopographic representation of flood features in flood models and, thus, increase the ability to identify high flood-risk prompt areas accurately. It would also help manage and maintain drainage assets, spatial planning of sustainable drainage systems, and property level flood resilience and insurance to better adapt to the effects of climate change. This study is another step towards standardising flood extent and impact surveying strategies.
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Zarzuelo, Carmen, Alejandro López-Ruiz, María Bermúdez, and Miguel Ortega-Sánchez. "Measurements and modeling of water levels, currents, density, and wave climate on a semi-enclosed tidal bay, Cádiz (southwest Spain)." Earth System Science Data 15, no. 7 (July 20, 2023): 3095–110. http://dx.doi.org/10.5194/essd-15-3095-2023.
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Abstract. Estuarine dynamics are highly complex as a result of the temperature and salinity gradients, as well as the multiple interactions between atmospheric, maritime, and hydrological forcing agents. Given the environmental and socioeconomic importance of estuaries and their current and future threats due to human interventions and climate change, it is of vital importance to characterize these dynamics, monitor their evolution, and quantify the expected impacts derived from climate change. This paper presents a hybrid database combining data obtained in six field surveys (in 2012, 2013, and 2015) and results from a physically based 3D numerical model for the Bay of Cádiz (southern Spain), a highly anthropized mesotidal estuary. The 3D dataset includes water levels, currents, density, and wave climate, allowing for an analysis of bay dynamics at different timescales ranging from intratidal processes to seasonal variabilities. The results offer an example of the potential uses of the dataset and include (1) an assessment of the spatial and seasonal variability of the estuarine dynamics and (2) an analysis of the effects of severe weather events. These examples provide convincing evidence regarding how the dataset can be employed in multiple research fields and applications, including ocean–bay interactions, water exchange between basins, longwave and shortwave propagation along creek systems, and energy extraction of tidal waves. Therefore, this hybrid dataset may be of significant interest for stakeholders and scientists from different sectors (water engineering, ecology, urban development, energy, etc.) working on the environmental management of the Gulf of Cádiz and other tidally dominated shallow bays. It can also serve as a benchmark test for numerical hydrodynamic models, infrastructure intervention assessments (e.g., dikes or breakwaters), or renewable energy conversion system models. The dataset is available at https://doi.org/10.5281/zenodo.7484186 (Zarzuelo et al., 2022b).
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Contreras, María Teresa, Jorge Gironás, Joannes Westerink, and Cristián Escauriaza. "Advanced numerical models for the propagation of floods with high-sediment concentrations in mountain rivers." E3S Web of Conferences 40 (2018): 06039. http://dx.doi.org/10.1051/e3sconf/20184006039.
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Rapid floods induced by extreme precipitation are common events in regions near the Andes mountain range. Growing urban development, combined with the changing climate and the influence of El Niño, have increased the exposure of the population in many regions of South America. Simulations of flash floods in these watersheds are very challenging, due to the complex morphology, the insufficient hydrometeorological data, and the uncertainty posed by the variability of sediment concentration. To address these issues, we develop a high-resolution numerical model of the non-linear shallow water equations, coupled with the mass conservation of sediment, and considering the density effects and changes of rheology in the momentum equation. Based on these simulations we develop a real-time early-warning system, by creating a surrogate model or meta-model from the simulations. Using a small set of parameters, we define storms for a wide range of meteorological conditions, and utilize the high-fidelity model results to create a database of flood propagation under different conditions. Through this second model we perform a sophisticated interpolation/regression, and approximate efficiently the flow depths and velocities. This is the first application of its kind in the Andes region, which can be used to improve the prediction of flood hazard in real conditions, employing low computational resources. We also create a framework to develop early warning systems, and to help decision makers and city planners in these mountain regions.
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Rossi, Sergio. "HOW CARBON IMMOBILIZATION FROM RESTORED MARINE FORESTS MAY HELP CLIMATE CHANGE MITIGATION PLANS?" Arquivos de Ciências do Mar 55, Especial (March 18, 2022): 202–18. http://dx.doi.org/10.32360/acmar.v55iespecial.78542.
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The ocean transformation due to the direct or indirect human influence is a fact. One of the most affected ecosystems are the benthic ones, where bottom trawling, urban/agricultural development and climate change (among other things) deeply transform the bottom communities. Among these threatened communities, the marine forest is the most extended. The marine forest is composed of benthic macroalgae, phanerogams and suspension feeders (sponges, corals, gorgonians, etc.) which conform three-dimensional living structures. Coral reefs, seaweeds, sponge grounds, seagrasses, oyster banks, cold water corals are some examples of this vast set of ecosystems dispersed all over the world. During the last two decades, the concept of Blue Carbon has been consolidated, describing the stocked carbon in vegetated coastal and marine habitats such as mangroves, salt marshes, seagrasses and seaweeds. There are also world-wide numbers about how much carbon is retained in the terrestrial forests, crops and soils. These systems act as carbon immobilizers from which we have proxies. Can we design and apply an ambitious shallow and deep marine forest restoration plan to help climate change mitigation? The aim of thispaper is developing a simplified realistic calculation of the role as carbon immobilizers of a restored marine forests in one area as a case study, setting up a huge restoration plan to help mitigating climate change, enhancing carbon retention. A shallow (10-30 meters depth) restoration plan of the marine animal forests with new technologies based on symbiotic artificial reefs, enhancing the role as carbon immobilizers and creating a protocol to help the climate change mitigation, is explained, using realistic numbers to calculate the real impact of such regenerative plan. Is time to have a much more applied and holistic view of what is in the ocean’s floors in terms of habitat composition, complexity and biomass stocks, implementing new methods and technologies that are already in our hands. It is also time to give a chance to the oceans in helping in the climate change mitigation plans applying brave new restoration approaches that may change our relation with the sea.
Keywords: marine restoration, marine animal forests, artificial reefs, transplantation,forest ecology.
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Dawes, W., R. Ali, S. Varma, I. Emelyanova, G. Hodgson, and D. McFarlane. "Modelling the effects of climate and land cover change on groundwater recharge in south-west Western Australia." Hydrology and Earth System Sciences 16, no. 8 (August 14, 2012): 2709–22. http://dx.doi.org/10.5194/hess-16-2709-2012.
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Abstract. The groundwater resource contained within the sandy aquifers of the Swan Coastal Plain, south-west Western Australia, provides approximately 60 percent of the drinking water for the metropolitan population of Perth. Rainfall decline over the past three decades coupled with increasing water demand from a growing population has resulted in falling dam storage and groundwater levels. Projected future changes in climate across south-west Western Australia consistently show a decline in annual rainfall of between 5 and 15 percent. There is expected to be a reduction of diffuse recharge across the Swan Coastal Plain. This study aims to quantify the change in groundwater recharge in response to a range of future climate and land cover patterns across south-west Western Australia. Modelling the impact on the groundwater resource of potential climate change was achieved with a dynamically linked unsaturated/saturated groundwater model. A vertical flux manager was used in the unsaturated zone to estimate groundwater recharge using a variety of simple and complex models based on climate, land cover type (e.g. native trees, plantation, cropping, urban, wetland), soil type, and taking into account the groundwater depth. In the area centred on the city of Perth, Western Australia, the patterns of recharge change and groundwater level change are not consistent spatially, or consistently downward. In areas with land-use change, recharge rates have increased. Where rainfall has declined sufficiently, recharge rates are decreasing, and where compensating factors combine, there is little change to recharge. In the southwestern part of the study area, the patterns of groundwater recharge are dictated primarily by soil, geology and land cover. In the sand-dominated areas, there is little response to future climate change, because groundwater levels are shallow and much rainfall is rejected recharge. Where the combination of native vegetation and clayey surface soils restricts possible infiltration, recharge rates are very sensitive to reductions in rainfall. In the northern part of the study area, both climate and land cover strongly influence recharge rates. Recharge under native vegetation is minimal and is relatively higher where grazing and pasture systems have been introduced after clearing of native vegetation. In some areas, the recharge values can be reduced to almost zero, even under dryland agriculture, if the future climate becomes very dry.
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Herawati, Jajuk, Indarwati Indarwati, and Raffiuddin Helmi. "Efektivitas Rendaman Bawang Merah (Allium cepa) dan Nutrisi Terhadap Hasil Hidroponik Pakcoy (Brassica rapa)." Journal of Applied Plant Technology 1, no. 1 (November 24, 2022): 48–60. http://dx.doi.org/10.30742/japt.v1i1.30.
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Hydroponic cultivation systems are increasingly popular among urban communities with not large land. This cultivation can provide benefits and effectiveness for those who carry it out. The wick system is one of the simple hydroponics methods that is easy to do, because it is a passive hydroponic system. This study aims to find out how the effect of shallot solution to the growth and production of bok coy plants on hydroponic cultivation of the wick system. Hydroponics of the wick system is a hydroponic method of the axis system, which is the simplest because it uses the principle of water capillarity. Distribution of nutrient solution towards root using axis intermediaries. This study used a Randomized Group Design (RDG) with 12 experimental units and the Least Significance Different (LSD) with an error rate of 5%. The concentration of shallot solution added is P0 (0%), P1(20%), and P2 (30%). The results showed that the treatment of AB mix nutrition as a hydroponic medium has a tendency to have a better effect on the growth parameters and yield of Pakcoy plants. AB mix treatment had a significant effect on production parameters, namely total wet weight, upper wet weight, root wet weight, and dry weight. Provision of shallot soak at concentrations of 20% and 30% added to hydroponic media with AB mix nutrition has not been able to improve the growth parameters and yield of Pakcoy.
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Clarkson, Peter A., and Thomas J. Priestley. "Shallow Water Wave Systems." Studies in Applied Mathematics 101, no. 4 (November 1998): 389–432. http://dx.doi.org/10.1111/1467-9590.00099.
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Schlurmann, Torsten, Widjo Kongko, Nils Goseberg, Danny Hilman Natawidjaja, and Kerry Sieh. "NEAR-FIELD TSUNAMI HAZARD MAP PADANG, WEST SUMATRA: UTILIZING HIGH RESOLUTION GEOSPATIAL DATA AND RESEASONABLE SOURCE SCENARIOS." Coastal Engineering Proceedings 1, no. 32 (January 19, 2011): 26. http://dx.doi.org/10.9753/icce.v32.management.26.
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Near-field tsunami propagation both in shallow water environments and bore-like wave propagation on land are conducted in this
study to obtain fundamental knowledge on the tsunami hazard potential in the city of Padang, Western Sumatra, Republic of
Indonesia. As the region proves a huge seismic moment deficit which has progressively accumulated since the last recorded
major earthquakes in 1797 and 1833, this investigation focuses on most reasonable seismic sources and possibly triggered nearshore
tsunamis in order to develop upgraded disaster mitigations programs in this densely-populated urban agglomeration located
on the western shore of Sumatra Island. Observations from continuous Global Positioning Satellite (cGPS) systems and
supplementary coral growth studies confirm a much greater probability of occurrence that a major earthquake and subsequent
tsunami are likely to strike the region in the near future. Newly surveyed and processed sets of geodata have been collected and
used to progress most plausible rupture scenarios to approximate the extent and magnitudes of a further earthquake. Based upon
this novel understanding, the present analysis applies two hydronumerical codes to simulate most probable tsunami run-up and
subsequent inundations in the city of Padang in very fine resolution. Run-up heights and flow-depths are determined stemming
from these most plausible rupture scenarios. Evaluation of outcome and performance of both numerical tools regarding impacts
of surge flow and bore-like wave fronts encountering the coast and inundating the city are thoroughly carried out. Results are
discussed not only for further scientific purposes, i.e. benchmark tests, but also to disseminate main findings to responsible
authorities in Padang with the objective to distribute the most probable dataset of plausible tsunami inundations as well as to
address valuable insights and knowledge for effective counter measures, i.e. evacuation routes and shelter building. Following
evacuation simulations based on rational assumptions and simplifications reveal a most alerting result as about 260.000 people
are living in the highly exposed potential tsunami inundation area in the city of Padang of which more than 90.000 people will
need more than 30 min. to evacuate to safe areas.
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Romo, Susana, and Eloy Bécares. "Water management of two shallow urban eutrophic lakes." Water Science and Technology 30, no. 10 (November 1, 1994): 299–302. http://dx.doi.org/10.2166/wst.1994.0540.
Full textAbstract:
The efficiency and effects of aluminium sulphate on water quality of two shallow urban eutrophic lakes of Madrid (Spain) is reported. Almost all the controlled variables improved with the treatment, especially nutrients, pH and transparency. The application of the method during spring and summer reduced nutrient content for the remainder of the seasons. However, phytoplankton density in both lakes needs supplementary measures for long-term control. The treatment seems not alter fish populations.