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1.
Modelling infiltration enhancement in a tropical urban catchment for improved stormwater management 总被引：1，自引：0，他引：1 
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下载免费PDF全文 To mitigate the impacts of impervious surfaces in urban areas, structures such as bioretention systems and permeable pavements have been installed to enhance infiltration in many countries. However, relatively little knowledge is available regarding the performance of such infiltration‐based structures in humid tropical and highly urbanized areas. This study investigates the feasibility of enhancing the infiltration of stormwater in tropical urbanized areas using Singapore as a case study. It first shows that the rainfall depth and intensity are both high, but the time interval between consecutive rainfall event is long in Singapore. It then numerically simulates single‐event local infiltration and finds that the fraction of infiltrated rainfall is actually high. It finally performs catchment‐scale simulations and finds that bioretention systems can enhance infiltration and groundwater recharge particularly during wet periods. However, local mounding of groundwater can be significant and can hinder the performance of those structures. Furthermore, with 5% of catchment area being converted to such structures, the infiltration of the entire catchment is enhanced but still not yet up to the natural level. To increase the overall effectiveness, future studies can look into bioretention systems with underdrain systems. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
2.
Permeable pavements (PPs) are widely implemented in urban areas to mimic natural hydrologic processes through enhancing infiltration, and reducing, delaying, and retaining surface runoff. However, its performance can be affected by shallow groundwater since high soil moisture may inhibit its infiltration and exfiltration. This study built a numerical model, which was calibrated and validated based on laboratory experiment data, to evaluate the water balance and retention of PP in shallow groundwater conditions. It assessed the impacts of shallow groundwater and the hydrologic effectiveness of different PP design measures (i.e., building a PP with a smaller storage depth, implementing an underdrain at different elevations, and installing an impermeable liner) on relieving the impacts. Shallower groundwater led to larger amounts of surface runoff and underdrain flow, and a higher chance of saturating the PP reservoir. The three design measures had both benefits and drawbacks in mimicking natural hydrologic cycle and retaining the performance of PP under extreme conditions (e.g., areas of very shallow groundwater tables and/or extreme rainfalls). A PP with a smaller storage depth resulted in less underdrain flow but was prone to saturation. It is, thus, more recommended for PP with more-permeable subsoils, which can avoid frequent pavement saturation. Although a shallower PP corresponds to a smaller storage volume and shorter hydraulic retention time, it can increase the applicability of PP to shallow groundwater areas, which is beneficial to the regional hydrologic environment. Installing an underdrain generated underdrain flow, which is a burden to the downstream drainage system. However, it significantly reduced the surface runoff and the chance of saturating the PP reservoir, which, thus, is more recommended for PP with less-permeable subsoils. Comparatively, elevating the underdrain is recommended in areas of shallow groundwater because it can reduce the frequency and amount of groundwater-induced underdrain flow. In addition, a higher underdrain together with an impermeable liner can create a storage depth, increase the retention duration, enhance exfiltration and evaporation without increasing the saturation risk. 相似文献
3.
Rainfall replenishes surface and subsurface water but is partially intercepted by a canopy. However, it is challenging to quantify the rainfall passing through the canopy (i.e. throughfall). This study derives simple‐to‐use empirical equations relating throughfall to canopy and rainfall characteristics. Monthly throughfall is calculated by applying a mass balance model on weather data from Singapore; Vancouver, Canada; and Stanford, USA. Regression analysis is then performed on the calculated throughfall with three dependent variables (i.e. maximum canopy storage, average rainfall depth and time interval between two consecutive rainfall in a month) to derive the empirical equations. One local equation is derived for each location using data from that particular location, and one global equation is derived using data from all three locations. The equations are further verified with calculated monthly throughfall from other weather data and actual throughfall field measurements, giving an accuracy of about 80–90%. The global equation is relatively less accurate but is applicable worldwide. Overall, this study provides a global equation through which one can quickly estimate throughfall with only information on the three variables. When additional weather data are available, one can follow the proposed methodology to derive their own equations for better estimates. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
4.
城市快速反应系统实验研究 总被引：1，自引：0，他引：1
在紧急的情况下，时间是非常重要的，因为几秒之差就会使营救结果截然不同。因此，为营救人员或当事人提供最佳路径，以缩短路途时间就变得非常重要。在ＧＩＳ和ＧＰＳ的支持下，以超图数据结构为基础，为控制台或当事人提供实时导航信息，可有效地减少路途时间。本文探讨了城市快速反应系统，怎样在超图数据结构的支持下，与ＧＩＳ和ＧＰＳ相结合，为系统操作者提供当前的实时位置及有关信息。 相似文献
5.
The principal natural source of fresh water on scattered coral atolls throughout the tropical Pacific Ocean is thin unconfined groundwater lenses within islet substrates. Although there are many threats to the viability of atoll fresh water lenses, salinization caused by large storm waves washing over individual atoll islets is poorly understood. In this study, a mathematical modeling approach is used to examine the immediate responses, longer-term behavior, and subsequent (partial) recovery of a Pacific atoll fresh water lens after saline damage caused by cyclone-generated wave washover under different scenarios. Important findings include: (1) the saline plume formed by a washover event mostly migrates downward first through the top coral sand and gravel substrate, but then exits the aquifer to the ocean laterally through the more permeable basement limestone; (2) a lower water table position before the washover event, rather than a longer duration of storm washover, causes more severe damage to the fresh water lens; (3) relatively fresher water can possibly be found as a preserved horizon in the deeper part of an aquifer after disturbance, especially if the fresh water lens extends into the limestone under normal conditions; (4) post-cyclone accumulation of sea water in the central depression (swamp) of an atoll islet prolongs the later stage of fresh water lens recovery. 相似文献
6.
电阻率层析成像的实质及其应用 总被引：5，自引：0，他引：5
电阻率层析成像技术是８０年代末期发展起来的一种地球物理勘探方法，本文分析了其实质，并介绍了用于电阻率层成像野外观测的ＭＣＯＨＭ－２１型仪器，最后通过实例说明了该方法的应用前景。 相似文献
7.
南沙海域中大陆坡沉积物中甾醇的地球化学研究 总被引：9，自引：1，他引：8
对南沙海域中大际坡柱沉积物中甾醇进行了分析,从中检出碳数为Ｃ２７－Ｃ３０的１１种甾醇生物标志化合物,它们的组成特征反映了沉积有机质主要来自浮游生物,陆源高等植物的贡献很少,不同沉积层段中甾醇的组成差异可能与生态环境有关,甾烷醇与甾烯醇比值随沉积深度而增加的趋势,指示了甾烯醇向甾烷醇的转化,这种转化可能是通过化学和生物化学的氢化作用实现的。 相似文献
8.
Harianto Rahardjo Mărgărit-Mircea Nistor Nurly Gofar Alfrendo Satyanaga Qin Xiaosheng Sabrina Ip Chui Yee 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2020,14(3):177-191
ABSTRACT This paper presents the spatial distribution, variation and trend of 5-day antecedent rainfall in Singapore based on rainfall data from 22 meteorological stations. The effect of climate was analyzed by dividing the study period into three decades i.e. Decade 1: 1982–1991, Decade 2: 1992–2001 and Decade 3: 2002–2011. Kriging interpolation was used for rainfall mapping. The results show that spatial distribution of 5-day antecedent rainfall does not coincide with that of the annual rainfall. The maximum annual rainfall occurred in the northwestern side of Singapore. On the other hand, the maximum 5-day antecedent rainfall occurred in the north and northeastern sides. The results of this study suggest that the climate change has increased the amount of 5-day antecedent rainfall quite significantly, i.e. from 420.5 (1987) to 592.9 mm (2006), thus affecting the vulnerability of the area with respect to rainfall-induced slope failure. The analyses also showed that most of slope failures were located in the north and northeast of Singapore between December and earlier March. More slope failures were observed in Decade 3 as compared to Decades 1 and 2. In other words, the analysis confirmed that 5-day antecedent rainfall had affected the slope stability in Singapore. 相似文献
9.
In tropical waters where temperatures are relatively stable,we investigated whether the relationship between phytoplankton growth and grazing loss rate acros s different habitats around Peninsular Malaysia can be attributed to its eutrophication states.We measured phytoplankton growth(μ) and grazing loss(g) rates in waters off Bachok Marine Research Station(BMRS),located northeast of Peninsular Malaysia.Chlorophyll-a(chl-a) concentration ranged from 2.90 to 15.78 μg/L and was dominated by nanoand micro-phytoplankton(2 μm in size).Using the Landry and Hassett dilution method,μ at BMRS ranged from 1.02 to 1.58/d whereas g varied from 0.07 to 0.88/d.Grazing accounted for 35% of the primary production at BMRS.A systematic review of available data in waters around Peninsular Malaysia,revealed how μ fluctuated over a wide range(0.01-1.80/d) and correlated with chl a distribution(R2=0.181,P0.001).However,the relationship was only significant at 9 μg/L chl a for mesotrophic waters and 16 μg/L chl a for eutrophic waters.In contrast,g ranged from 0.00 to 1.01/d,and correlated with μ at all locations.The g/μslope ranged from 19% to 84%,and was generally similar for waters around Peninsular Malaysia.However,all the g/μ slopes had a positive y-intercept except for BMRS,and this seemed to suggest the availability of alternative prey supporting grazing at the other stations. 相似文献
10.
地质断层的运动模式与科学家曾经预期的并不相同。目前,科学家试图对地震的活动习性形成全新的认识,Glennda Chui对此进行了报道。 相似文献