Stormwater control impacts on runoff volume and peak flow: A meta-analysis of watershed modelling studies     

Colin D. Bell  Jordyn M. Wolfand  Chelsea L. Panos  Aditi S. Bhaskar  Ryan L. Gilliom  Terri S. Hogue  Kristina G. Hopkins  Anne J. Jefferson 《水文研究》2020,34(14):3134-3152

Decades of research has concluded that the percent of impervious surface cover in a watershed is strongly linked to negative impacts on urban stream health. Recently, there has been a push by municipalities to offset these effects by installing structural stormwater control measures (SCMs), which are landscape features designed to retain and reduce runoff to mitigate the effects of urbanisation on event hydrology. The goal of this study is to build generalisable relationships between the level of SCM implementation in urban watersheds and resulting changes to hydrology. A literature review of 185 peer-reviewed studies of watershed-scale SCM implementation across the globe was used to identify 52 modelling studies suitable for a meta-analysis to build statistical relationships between SCM implementation and hydrologic change. Hydrologic change is quantified as the percent reduction in storm event runoff volume and peak flow between a watershed with SCMs relative to a (near) identical control watershed without SCMs. Results show that for each additional 1% of SCM-mitigated impervious area in a watershed, there is an additional 0.43% reduction in runoff and a 0.60% reduction in peak flow. Values of SCM implementation required to produce a change in water quantity metrics were identified at varying levels of probability. For example, there is a 90% probability (high confidence) of at least a 1% reduction in peak flow with mitigation of 33% of impervious surfaces. However, as the reduction target increases or mitigated impervious surface decreases, the probability of reaching the reduction target also decreases. These relationships can be used by managers to plan SCM implementation at the watershed scale.  相似文献   

Assessing the effects of catchment‐scale urban green infrastructure retrofits on hydrograph characteristics          下载免费PDF全文

Kimberly M. Jarden  Anne J. Jefferson  Jennifer M. Grieser 《水文研究》2016,30(10):1536-1550

Run‐off from impervious surfaces has pervasive and serious consequences for urban streams, but the detrimental effects of urban stormwater can be lessened by disconnecting impervious surfaces and redirecting run‐off to decentralized green infrastructure. This study used a before–after‐control‐impact design, in which streets served as subcatchments, to quantify hydrologic effectiveness of street‐scale investments in green infrastructure, such as street‐connected bioretention cells, rain gardens and rain barrels. On the two residential treatment streets, voluntary participation resulted in 32.2% and 13.5% of parcels having green infrastructure installed over a 2‐year period. Storm sewer discharge was measured before and after green infrastructure implementation, and peak discharge, total run‐off volume and hydrograph lags were analysed. On the street with smaller lots and lower participation, green infrastructure installation succeeded in reducing peak discharge by up to 33% and total storm run‐off by up to 40%. On the street with larger lots and higher participation, there was no significant reduction in peak or total stormflows, but on this street, contemporaneous street repairs may have offset improvements. On the street with smaller lots, lag times increased following the first phase of green infrastructure construction, in which streetside bioretention cells were built with underdrains. In the second phase, lag times did not change further, because bioretention cells were built without underdrains and water was removed from the system, rather than just delayed. We conclude that voluntary green infrastructure retrofits that include treatment of street run‐off can be effective for substantially reducing stormwater but that small differences in design and construction can be important for determining the level of the benefit. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Sensitivity of a hydraulic model to channel erosion uncertainty during extreme flooding          下载免费PDF全文

Jefferson S. Wong  Jim E. Freer  Paul D. Bates  David A. Sear  Elisabeth M. Stephens 《水文研究》2015,29(2):261-279

Recent research into flood modelling has primarily concentrated on the simulation of inundation flow without considering the influences of channel morphology. River channels are often represented by a simplified geometry that is implicitly assumed to remain unchanged during flood simulations. However, field evidence demonstrates that significant morphological changes can occur during floods to mobilize the boundary sediments. Despite this, the effect of channel morphology on model results has been largely unexplored. To address this issue, the impact of channel cross‐section geometry and channel long‐profile variability on flood dynamics is examined using an ensemble of a 1D–2D hydraulic model (LISFLOOD‐FP) of the ~1 : 2000 year recurrence interval floods in Cockermouth, UK, within an uncertainty framework. A series of simulated scenarios of channel erosional changes were constructed on the basis of a simple velocity‐based model of critical entrainment. A Monte‐Carlo simulation framework was used to quantify the effects of this channel morphology together with variations in the channel and floodplain roughness coefficients, grain size characteristics and critical shear stress on measures of flood inundation. The results showed that the bed elevation modifications generated by the simplistic equations reflected an approximation of the observed patterns of spatial erosion that enveloped observed erosion depths. The effect of uncertainty on channel long‐profile variability only affected the local flood dynamics and did not significantly affect the friction sensitivity and flood inundation mapping. The results imply that hydraulic models generally do not need to account for within event morphodynamic changes of the type and magnitude of event modelled, as these have a negligible impact that is smaller than other uncertainties, e.g. boundary conditions. Instead, morphodynamic change needs to happen over a series of events to become large enough to change the hydrodynamics of floods in supply limited gravel‐bed rivers such as the one used in this research. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Assessing the sustainability of underground space usage �� A toolkit for testing possible urban futures     

D.V.L.HUNT  I.JEFFERSON  C.D.F.ROGERS 《山地科学学报》2011,8(2):211-222

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Trends,drivers and impacts of changes in swidden cultivation in tropical forest-agriculture frontiers: A global assessment     

Nathalie van Vliet  Ole Mertz  Andreas Heinimann  Tobias Langanke  Unai Pascual  Birgit Schmook  Cristina Adams  Dietrich Schmidt-Vogt  Peter Messerli  Stephen Leisz  Jean-Christophe Castella  Lars Jørgensen  Torben Birch-Thomsen  Cornelia Hett  Thilde Bech-Bruun  Amy Ickowitz  Kim Chi Vu  Kono Yasuyuki  Jefferson Fox  Christine Padoch  Alan D. Ziegler 《Global Environmental Change》2012,22(2):418-429

This meta-analysis of land-cover transformations of the past 10–15 years in tropical forest-agriculture frontiers world-wide shows that swidden agriculture decreases in landscapes with access to local, national and international markets that encourage cattle production and cash cropping, including biofuels. Conservation policies and practices also accelerate changes in swidden by restricting forest clearing and encouraging commercial agriculture. However, swidden remains important in many frontier areas where farmers have unequal or insecure access to investment and market opportunities, or where multi-functionality of land uses has been preserved as a strategy to adapt to current ecological, economic and political circumstances. In some areas swidden remains important simply because intensification is not a viable choice, for example when population densities and/or food market demands are low. The transformation of swidden landscapes into more intensive land uses has generally increased household incomes, but has also led to negative effects on the social and human capital of local communities to varying degrees. From an environmental perspective, the transition from swidden to other land uses often contributes to permanent deforestation, loss of biodiversity, increased weed pressure, declines in soil fertility, and accelerated soil erosion. Our prognosis is that, despite the global trend towards land use intensification, in many areas swidden will remain part of rural landscapes as the safety component of diversified systems, particularly in response to risks and uncertainties associated with more intensive land use systems.  相似文献   

Mineral Potential Modelling for the Greater Nahanni Ecosystem Using GIS Based Analytical Methods     

J. R. Harris  D. Lemkow  C. Jefferson  D. Wright  H. Falck 《Natural Resources Research》2008,17(2):51-78

Mineral potential within the Greater Nahanni Ecosystem (GNE) was modelled in a Geographic Information System (GIS) for four different deposit types: (1) SEDEX (stratiform shale-hosted sedimentary exhalative Zn–Pb–Ag), (2) ‘Carbonate-Fault’ (carbonate-hosted zinc–lead–silver associated with major faults), (3) ‘Intrusion-Related’ (includes skarn, rare metals and gemstones) and (4) Carlin-Type gold as lode and/or derived placer deposits. This mineral potential modelling study integrates data collected during the Nahanni Mineral and Energy Resource Assessment (MERA) undertaken from 2003 to 2007. The results have contributed to the process of determining the geographic boundaries of the proposed expansion of the Nahanni National Park Reserve. Four mineral potential maps were produced (one for each deposit type) using a knowledge-driven approach. A weighting scheme based on integrated mineral deposit and regional geological knowledge was derived for the various evidence maps for each deposit model using expert opinion. The four potential maps were then combined into a final potential map using a maximum operator. Plots showing the efficiency of the models (mineral potential maps) for predicting the known occurrences of the four deposit types show that partial data sets provide reasonable predictions of the remaining known mineral prospects, occurrences and deposits. Hydrocarbon potential from Nahanni MERA 1 was added to the final potential map to ensure that both mineral and energy potential data were incorporated into the park configuration modelling.  相似文献   

Protecting small cetaceans from coastal development: Impact assessment and mitigation experience in Hong Kong     

Thomas A. Jefferson  Samuel K. Hung  Bernd Würsig 《Marine Policy》2009

Since the early 1990s, there has been an active program in Hong Kong to manage and protect local populations of small cetaceans from the effects of massive development in the area. This paper reviews the progress that has been made. Only two species regularly occur there: the Indo-Pacific humpback dolphin and the finless porpoise. Because most development has occurred in the western waters of Hong Kong, where generally only the humpback dolphin occurs, most of the work has been conducted on that species. Development of large infrastructure projects (such as airports, bridges, expressways, power plants, fuel facilities, and container ports) in Hong Kong often results in land reclamation, dredging and dumping of spoils, pipe and cable laying, percussive and bored piling work, underwater blasting, large increases in vessel traffic, and other impacts. Several mitigation measures have been used with varying levels of success, including bubble curtains/jackets, exclusion zones, ramping up of piling hammers, acoustic decoupling of noisy equipment, vessel speed limits, no-dumping policies, and silt curtains. Baseline, construction-phase, and operational-phase cetacean monitoring is often conducted to evaluate the success of conservation measures put into place. The Environmental Impact Assessment process in Hong Kong has involved cetaceans to a degree perhaps higher than anywhere else in the world, and much can be learned from studying the successes and failures of this situation.  相似文献   

Low reproductive success for copepods during a bloom of the non‐aldehyde‐producing diatom Cerataulina pelagica in the North Adriatic Sea     

Adrianna Ianora  Raffaella Casotti  Mauro Bastianini  Christophe Brunet  Giuliana D’Ippolito  Francesco Acri  Angelo Fontana  Adele Cutignano  Jefferson T. Turner  Antonio Miralto 《Marine Ecology》2008,29(3):399-410

Egg production rates and/or hatching success in the copepods Acartia clausi, Calanus helgolandicus and Temora longicornis were negatively affected by a late spring (May–June 2003) phytoplankton bloom in the North Adriatic Sea, dominated mainly by the large diatom Cerataulina pelagica. Highest total concentrations of 3.3·10⁴ cells·ml^?1 were located in the vicinity of the Po River, which also corresponded to the area where the highest numbers of phaeophorbides were measured (0.779, 0.528 and 0.419 μg·l^?1, respectively, compared to an average of the remaining stations of 0.183 ± 0.049 SD), suggesting some grazing on the bloom. Phytoplankton biomass in terms of carbon was dominated by diatoms, representing on average 42% of total phytoplankton carbon and more than 80% at several stations. Cerataulina pelagica, Cyclotella spp., Chaetoceros spp. and small unidentified centric diatoms dominated the diatom community numerically but C. pelagica was by far the dominant diatom in terms of carbon due to its large cell size. This species represented more than 60% of the diatom biomass at nine of the 14 stations sampled, and was absent only at one station, which was the most offshore station sampled during the cruise. Although polyunsaturated aldehydes (PUAs) were not detected, other oxylipins which are hydroxy and keto derivatives of eicosapentaenoic and docosahexaenoic acids that affect copepod reproduction were found in these samples. Hence, we can attribute the negative impact of diatoms not only to PUAs, as previously believed, but also to these compounds. This is the first direct evidence of the presence of oxylipins other than PUAs in marine blooms dominated by diatoms.  相似文献   

Refractory Black Carbon Results and a Method Comparison between Solid-state Cutting and Continuous Melting Sampling of a West Antarctic Snow and Firn Core     

Luciano MARQUETTO  Susan KASPARI  Jefferson Cardia SIMOES  Emil BABIK 《大气科学进展》2020,37(5):545-554

This work presents the refractory black carbon(rBC)results of a snow and firn core drilled in West Antarctica(79°55'34.6"S,94°21'13.3"W)during the 2014?15 austral summer,collected by Brazilian researchers as part of the First Brazilian West Antarctic Ice Sheet Traverse.The core was drilled to a depth of 20 m,and we present the results of the first 8 m by comparing two subsampling methods—solid-state cutting and continuous melting—both with discrete sampling.The core was analyzed at the Department of Geological Sciences,Central Washington University(CWU),WA,USA,using a single particle soot photometer(SP2)coupled to a CETAC Marin-5 nebulizer.The continuous melting system was recently assembled at CWU and these are its first results.We also present experimental results regarding SP2 reproducibility,indicating that sample concentration has a greater influence than the analysis time on the reproducibility for low rBC concentrations,like those found in the Antarctic core.Dating was carried out using mainly the rBC variation and sulfur,sodium and strontium as secondary parameters,giving the core 17 years(1998?2014).The data show a well-defined seasonality of rBC concentrations for these first meters,with geometric mean summer/fall concentrations of 0.016μg L^?1 and geometric mean winter/spring concentrations of 0.063μg L^?1.The annual rBC concentration geometric mean was 0.029μg L^?1(the lowest of all rBC cores in Antarctica referenced in this work),while the annual rBC flux was 6.1μg m^?2 yr^?1(the lowest flux in West Antarctica records so far).  相似文献   

Calcium,Na, K and Mg Concentrations in Seawater by Inductively Coupled Plasma‐Atomic Emission Spectrometry: Applications to IAPSO Seawater Reference Material,Hydrothermal Fluids and Synthetic Seawater Solutions     

Philippe Besson  Jefferson Degboe  Benjamin Berge  Valérie Chavagnac  Sébastien Fabre  Gilles Berger 《Geostandards and Geoanalytical Research》2014,38(3):355-362

We report a measurement procedure to determine simultaneously the major cation concentrations (Na, Ca, K and Mg) of seawater‐derived solutions by inductively coupled plasma‐atomic emission spectrometry. The best results were obtained when the IAPSO (‘standard’) seawater reference material was diluted by thirty times with Milli‐Q^® water. We obtained an average reference value r_K (the ratio of the mass fraction of potassium to that of chlorine, i.e., (g kg^?1)/(g kg^?1)) for IAPSO seawater of 0.0205 ± 0.0006 (2.9% RSD), not significantly different from 0.0206 ± 0.0005 (2.4% RSD) for seawater composition reported in the literature. The measured Na, Ca and Mg concentrations correspond to r_Na, r_Ca and r_Mg values of 0.5406 ± 0.0026 (0.5% RSD), 0.02192 ± 0.00048 (2.2% RSD) and 0.06830 ± 0.00047 (0.7% RSD), respectively, in line with previous values measured by wet‐chemistry and atomic absorption spectrophotometry or wet‐chemical titration. Our measurement procedure was used successfully on synthetic seawater solutions and high‐temperature hydrothermal fluids.  相似文献