Analytical solutions for tidal propagation in a rectangular basin

The tidal propagation in a rectangular basin of an estuary has been studied in this paper. The dynamic response of the tidal current and elevation inside the basin has been obtained using the concept of Kelvin waves and spectrum of Poincare waves. In this study, we have found that initial tidal elevations are amplified near the closed end of the basin or at the tidal barrier site.     

巢湖典型子流域上下游水塘对暴雨径流氮磷去除效率比较

从流域上下游环境条件及氮磷输出强度差异出发,探讨上下游水塘对径流氮磷去除的特征及效率,选取巢湖小柘皋河源头流域上下游水塘开展水塘去除暴雨径流氮磷的对比试验,研究暴雨及暴雨间期上下游水塘氮磷去除效率差异及原因,为流域上下游设计不同类型净化塘去除氮磷提供科学依据.结果表明:暴雨期,上游径流氮磷浓度高于下游,且颗粒态所占比例上游大于下游,流域上游应作为防治暴雨径流氮磷流失的重点区域;暴雨期,上游塘对暴雨径流中的氮磷去除效果明显,氮、磷去除率分别为74％和52％,且对颗粒态去除效果好于溶解态,下游塘没有表现出明显的去除效果;暴雨间期,上游塘塘内氮磷浓度平均下降50％和20％,下游塘则分别为72％和16％,且均以溶解态去除为主;水塘去除暴雨径流氮磷有一定的浓度适用范围,浓度过低,去除效果不明显;流域部位不同引起入塘径流氮磷浓度和形态的差异是上下游水塘对暴雨径流去除效果差异的主要外部原因.流域上游出山口,可以在渗透性好的山前洪积扇上构建深水宽塘,通过增加暴雨径流拦截量和降低流速增强物理沉降作用,实现暴雨径流氮磷的高效去除;流域下游农田区,宜构建水面较大的浅滩湿地,通过延长滞留时间和促进生物活动增强去除暴雨径流氮磷的效果.     

Field investigation of a dry detention pond with underground detention storage

Abstract

A dry pond is an urban drainage component designed to temporarily store stormwater runoff and to encourage infiltration of surface water to the subsurface layer. This paper investigates field measurement of a dry pond at Taiping Health Clinic, Perak, Malaysia that has been functioning well for five years. The pond has a surface area of 195 m², maximum depth of 32 cm, and a storage capacity of 31.88 m³. The study focused on the infiltration functionality of the constructed dry pond and the results show that it has an average infiltration rate of 125 mm/h and dries up in 330 min after being filled to a depth of 31 mm. A public-domain hydrological model was then employed to simulate hydrographs of ponding and draining, the results of which matched observations with 86–98% accuracy. These results can lead to better understanding of the system and allow duplication of such a drainage design elsewhere.

Editor D. Koutsoyiannis

Citation Lai, S.H. and Mah, D.Y.S., 2012. Field investigation of a dry detention pond with underground detention storage. Hydrological Sciences Journal, 57 (6), 1249–1255.     

Application of semi‐distributed hydrological model for basin level water balance of the Ken basin of Central India

In the present study, a semi‐distributed hydrological model soil and water assessment tool (SWAT) has been employed for the Ken basin of Central India to predict the water balance. The entire basin was divided into ten sub basins comprising 107 hydrological response units on the basis of unique slope, soil and land cover classes using SWAT model. Sensitivity analysis of SWAT model was performed to examine the critical input variables of the study area. For Ken basin, curve number, available water capacity, soil depth, soil evaporation compensation factor and threshold depth of water in the shallow aquifer (GWQ_MN) were found to be the most sensitive parameters. Yearly and monthly calibration (1985–1996) and validation (1997–2009) were performed using the observed discharge data of the Banda site in the Ken basin. Performance evaluation of the model was carried out using coefficient of determination, Nash–Sutcliffe efficiency, root mean square error‐observations standard deviation ratio, percent bias and index of agreement criterion. It was found that SWAT model can be successfully applied for hydrological evaluation of the Ken basin, India. The water balance analysis was carried out to evaluate water balance of the Ken basin for 25 years (1985–2009). The water balance exhibited that the average annual rainfall in the Ken basin is about 1132 mm. In this, about 23% flows out as surface run‐off, 4% as groundwater flow and about 73% as evapotranspiration. Copyright © 2013 John Wiley & Sons, Ltd.     

Evaluation of multi‐use stormwater detention basins for improved urban watershed management

Detention basins are used to capture postdevelopment runoff and control the peak discharge of the outflow using orifices and weirs. The use of detention basins is typical practice in the construction of new developments on the fringe of existing urban areas, such as the Ulsan–Hwabong district in the city of Ulsan, South Korea. In this study, the required volume and flooding area of a detention basin was determined to control development outflow peaks for 2‐year, 10‐year, and 100‐year design storms with type II rainfall distributions as characterized by the US Department of Agriculture's Soil Conservation Service method. The rainfall–runoff simulation model used was the US Environmental Protection Agency's Storm Water Management Model (EPA‐SWMM) 5, which is the latest version of the software, updated for Windows. We designed three cases of detention basins multi‐staged by 2‐year, 10‐year, and 100‐year design storms and verified the designs with the application of 49 years (1961–2009) of hourly historical rainfall data. The three detention basin designs were compared in terms of the total construction and land costs as well as the benefits associated with recreational facilities or parking lot use. As a result, the design sizes of the detention basins are slightly greater than the actual sizes needed based on the historical rainfall application. Multi‐use detention basins (MDBs) based on 2‐year and 10‐year design storms were found to yield 37.4% and 22.8% benefits, respectively, for recreational facility use compared with detention basins without multi‐use space, and the results also indicate that benefits accrue after 6.5 years for parking lot use. The results of this study suggest that an MDB based on a 2‐year design storm is the most cost‐effective design among the three cases considered for Ulsan, South Korea. Copyright © 2012 John Wiley & Sons, Ltd.     

Discontinuous Galerkin methods for modeling Hurricane storm surge

Storm surge due to hurricanes and tropical storms can result in significant loss of life, property damage, and long-term damage to coastal ecosystems and landscapes. Computer modeling of storm surge can be used for two primary purposes: forecasting of surge as storms approach land for emergency planning and evacuation of coastal populations, and hindcasting of storms for determining risk, development of mitigation strategies, coastal restoration and sustainability.Storm surge is modeled using the shallow water equations, coupled with wind forcing and in some events, models of wave energy. In this paper, we will describe a depth-averaged (2D) model of circulation in spherical coordinates. Tides, riverine forcing, atmospheric pressure, bottom friction, the Coriolis effect and wind stress are all important for characterizing the inundation due to surge. The problem is inherently multi-scale, both in space and time. To model these problems accurately requires significant investments in acquiring high-fidelity input (bathymetry, bottom friction characteristics, land cover data, river flow rates, levees, raised roads and railways, etc.), accurate discretization of the computational domain using unstructured finite element meshes, and numerical methods capable of capturing highly advective flows, wetting and drying, and multi-scale features of the solution.The discontinuous Galerkin (DG) method appears to allow for many of the features necessary to accurately capture storm surge physics. The DG method was developed for modeling shocks and advection-dominated flows on unstructured finite element meshes. It easily allows for adaptivity in both mesh (h) and polynomial order (p) for capturing multi-scale spatial events. Mass conservative wetting and drying algorithms can be formulated within the DG method.In this paper, we will describe the application of the DG method to hurricane storm surge. We discuss the general formulation, and new features which have been added to the model to better capture surge in complex coastal environments. These features include modifications to the method to handle spherical coordinates and maintain still flows, improvements in the stability post-processing (i.e. slope-limiting), and the modeling of internal barriers for capturing overtopping of levees and other structures. We will focus on applications of the model to recent events in the Gulf of Mexico, including Hurricane Ike.     

Vegetation responses to integrated water management in the Ejina basin,northwest China

The Ejina basin, which is located in arid and semi‐arid areas of northwest China, has experienced severe environmental deterioration in the past several decades, and an exploratory project was launched by the Chinese Government in 2001 to restore this degraded ecosystem. In this study, multi‐scale remotely sensed data and field investigations were used to quantify the responses of vegetation to the implementation of integrated water management under this project. In terms of the seasonal accumulated Normalized Difference Vegetation Index (SAN) variation, (1) the vegetation in 80·4% of the oasis regions showed an increasing or recovering trend, and increasing SAN trends with a magnitude greater than 0·14 a^?1 mainly resulted from cultivated land reclamation; (2) the vegetation in 91·5% of the desert regions presented an increasing trend, and the statistically significant trends mainly appeared in the middle and lower Ejina basin; (3) the vegetation in 19·6% of oasis and 5·1% of desert regions showed a decreasing or degrading trend, mainly where rivers diminished and along artificial concrete canals; and (4) opposite signs of vegetation trends occurred simultaneously along some natural rivers experiencing water reduction, with a decreasing trend generally appearing in the high SAN regions, whereas an increasing trend was seen in the low SAN regions. The broad vegetation recovery observed was due to the comprehensive improvement of the water environment, which was attributed to both the increase in runoff entering the Ejina basin and the adoption of engineering measures. Vegetation degradation in the area mainly resulted from deterioration of the local water environment, which was closely related to the problems of water management. The results of this study can be used as a reference for adjusting the current water resource management strategy to effectively restore this ecosystem. Copyright © 2011 John Wiley & Sons, Ltd.     

Heavy metal concentrations during storm events in a rehabilitated industrialized catchment

Water quality data collected on a fortnightly or monthly basis are inadequate for assessment and modelling of many water quality problems as storm event samples are underrepresented or missed. This paper examines the stormflow dynamics of heavy metals (Pb, Cu, Cd and Zn) in the Nant‐y‐Fendrod stream, South Wales, which has been affected by 250 years of metal smelting, followed by 35 years of landscape rehabilitation measures. For storm events of contrasting (very dry and very wet) antecedent conditions in May 2000 and February 2001, respectively, temporal changes in streamwater heavy metal concentrations above and below an in‐line flood detention lake are analysed. At the upstream site, peaks in total metal concentration were recorded on the rising limb for Pb (0·150 mg l^?1) and Cu (0·038 mg l^?1) but on the falling limb for Zn (1·660 mg l^?1) and Cd (0·006 mg l^?1) in the summer 2000 storm event, yielding clockwise and anticlockwise hysteretic loops respectively. In contrast, metal concentrations, although high throughout the winter storm event, were diluted somewhat during the storm peak itself. The Pb and Cu appear to be supplied by quickflow processes and transported in close association with fine sediment, whereas Zn and Cd are delivered to the channel and lake by slower subsurface seepage in dissolved form. In the winter 2001 event, antecedent soil moisture and shallow groundwater levels were anomalously high and seepage sources of dissolved metals dominated. Downstream of the lake, Pb and Cu levels and suspended sediment were high in the summer storm, but low in the winter storm, suggesting retention with deposition of fine sediment in the lake during the latter. In the winter storm, Zn and Cd levels were higher downstream than upstream of the lake, perhaps because of additional seepage inputs from the surrounding slopes, which failed to have an impact during summer. An understanding of the complex interplay of antecedent soil moisture and the dynamics of subsurface seepage pathways in relation to the three‐dimensional distribution of sources is important in modelling heavy metal fluxes and levels in contaminated urban catchments. Copyright © 2003 John Wiley & Sons, Ltd.     

Analytical solutions for water flow passing over a vegetal area

This study is aimed at investigating the vertical velocity profile of flow passing over a vegetal area by an analytical approach. The soil ground is considered as pervious and thus non-zero velocity at the ground surface can be estimated. The soil and vegetation layers are regarded as homogeneous and isotropic porous media. Therefore the solution of the flow can be obtained by applying the theory of turbulent flow and Biot’s theory of poroelasticity after dividing the flow field into three layers: homogenous water, vegetation and pervious soil. The velocity distribution is compared with the experimental data of [Rowiński PM, Kubrak J. A mixing-length model for predicting vertical velocity distribution on flows through emergent vegetation. J Hydrol Sci 2002;47(6):893–904] to show its validity. In addition, five dimensionless parameters denoting the variation of slope, permeability of soil, Reynolds stress, density of vegetation, and relative height of vegetation are proposed to reveal their effects on the surface water flow. The analytical solutions of flow velocity can also be simplified into simpler expressions to describe the flow passing over a non-vegetated area.     

利用重力卫星GRACE监测亚马逊流域2002—2010年的陆地水变化

本文利用GRACE (Gravity Recovery and Climate Experiment) 卫星重力资料研究了亚马逊流域2002—2010年的陆地水变化,并与水文模式和降雨资料进行了比较分析.在年际尺度上,GRACE结果表明:2002—2003年和2005年,亚马逊流域发生明显的干旱现象;2007年至2009年,陆地水呈逐年增加的趋势,并在2009年6月变化值达到最大,为772±181 km3;自2009年6月至2010年12月,陆地水总量又急剧减少了1139±262 km3,这相当于全球海平面上升3.2±0.7 mm所需的水量.水文模式得到的亚马逊流域陆地水在2010年也表现出明显的减少.降雨资料与GRACE观测资料有很好的一致性.在2005年和2010年的干旱期,亚马逊流域的降雨显著减少,说明降雨是亚马逊流域陆地水变化的重要因素.此外,本文采用的尺度因子的方法有效地降低了GRACE后处理误差的影响.     

Chemical effects of a near-to-nature detention pond on a small urban headwater

The near-to-nature approach has been established as best practice for stormwater management. However, pollutant mobility within such systems and its impact on small receiving waters are partly unexplained. The study takes place in an urbanised headwater catchment in south-western Germany with an area of 0.4 km². Runoff from roofs, roads, parking lots and gardens is collected in wells or trenches and stored in private and public dry detention basins. Accordingly, this study investigates pollutant input to a detention pond, removal efficiency and the associated effects on the receiving water.Grab samples with high temporal resolution of the receiving water (16 flood events with 315 samples and 41 baseflow samples), the three inflows of the detention basin and its outflow (four flood events with 64 samples) were taken. The outflow of the dry pond is recovered in the hydro- and chemographs of the receiving water. Runoff from roads with increased traffic volume caused the highest PAH inputs and runoff from the residential area showed the highest zinc concentrations, which partly infringe European Environmental Quality Standards. Yearly pollutant inputs (DOC, TSS, PAH, nutrients, metals) from the settlement into the tributary are reduced in the detention pond by up to 80%.     

Morphological records of storm floods exemplified by the impact of the 1872 Baltic storm on a sandy spit system in south‐eastern Denmark

Beach‐ridge systems are important geo‐archives providing evidence for past wave climate including catastrophic storm flood events. This study investigates the morphological impacts of the 1872 Baltic storm flood on a beach‐ridge system (sandy spit) in south‐eastern Denmark and evaluates the frequency of extreme storm flood events in the area over a longer time perspective. This paper combines field studies of morphology and sedimentary deposits, studies of historical maps, digital terrain model, ground‐penetrating radar profiles, and luminescence dating. Sea water reached 2.8 m above mean sea level (amsl) during peak inundation and, based on studies of the morphological impacts of the 1872 storm flood, the event can be divided into four phases. Phase 1: increasing mean water levels and wave activity at the beach brought sediments from the beach (intertidal bars and normal berm) higher up in the profile and led to the formation of a storm‐berm. Phase 2: water levels further increased and sediment in the upper part of the profile continued to build up the storm‐berm. Phase 3: water levels now reached the top of the dune ridge and were well above the storm‐berm level. Sea water was breaching the dune ridge at several sites and wash‐over fans were generated until a level where the mean water level had dropped too much. Phase 4: the non‐vegetated wash‐over fans functioned as pathways for aeolian sand transport and relatively high dunes were formed in particular along the margins of the fan where aeolian sand was trapped by existing vegetation. The studied beach‐ridge system records about 4500 years of accumulation; the storm flood sediments described are unique suggesting that the 1872 Baltic storm flood event was an extreme event. Thus studies of beach‐ridge systems form a new source for understanding storm surge risk. Copyright © 2013 John Wiley & Sons, Ltd.     

Seasonal water storage change of the Yangtze River basin detected by GRACE

1 Introduction Large-scale mass redistribution, or temporal varia- tion of mass within the Earth system, the driving force of interactions between solid Earth and geophysical fluids envelope (i.e., atmosphere, ocean, and hydro- sphere), is an important geophysical process critical to human life. Most of the interactions between solid Earth and the atmosphere/oceans happen at seasonal and inter-annual time scales. One important contribu- tor of mass redistribution at seasonal and inter-annual …     

Using nocturnal water level fluctuations for estimating seepage from stormwater detention systems

A simple method, modified from White's method, was developed and verified for estimating seepage from two stormwater detention areas (SDAs) for 2 years, using night‐time changes in surface water levels. The SDAs were located in warm sub‐tropical Florida where the assumption of negligible night‐time evaporation for White's method does not hold true. Daily seepage was estimated using the nocturnal water level fluctuations on no flow days during winter when evaporation losses were insignificant. Specific yield, rather than the composite specific yield, provided accurate seepage estimates. The average annual seepage from the two SDAs was 2.03 m/year. At almost 70% of surface flows, seepage is a significant contributor to regional surface and sub‐surface flows. Comparison of seepage estimates from the night‐time method (NM) and the water balance (WB) method showed that the NM‐based estimates were within the range of the estimates from the WB method. At SDA1, the differences between the NM and WB estimates were 1% and 11%, for the 2 years. The discrepancy between the two estimates became higher (27% and 23%) at SDA2. Larger differences at SDA2 were because of higher error in quantifying pumped inflows for the WB method. Successful performance of NM combined with its low resource (single well monitoring) requirements will help quantify seepage from detention areas and other similar features (e.g. ponds, constructed wetlands) in warmer climates. A scale‐up for the Caloosahatchee River basin showed that seepage from SDA's accounted for 15% of annual river flows indicating the importance of seepage in evaluating water and chemical balances. Copyright © 2015 John Wiley & Sons, Ltd.     

柴达木盆地苏干湖表层沉积与尘暴事件——元素示踪的初步结果

通过分析苏干湖地区10个地表表层沉积物、9个大气降尘(含2个尘暴降尘)、16个湖泊表层沉积物等样品的8种常量-微量元素和11种稀土元素的含量,以及同类沉积不同元素含量和不同沉积同一元素含量的相关性,结果表明,在湖泊沉积体系中Al、Fe、Sc含量的变化与强风-尘暴过程有关,指示了湖泊沉积碎屑颗粒风成输入的可能性．元素Fe、Sc含量在3种不同的沉积物中差异不大,与尘暴事件的强度和频次有关．稀土元素结果显示3类沉积具有同源性．苏干湖沉积可以用来重建研究区尘暴演化历史．     

太湖流域(江苏省)水质污染空间特征

基于SPSS 20.0统计软件,对太湖流域(江苏省)9个三级生态功能分区和湖体28项水质指标数据分别进行处理,从原始监测数据中提取出5个主成分,计算其贡献率和主成分得分值,研究主要污染因子的组合,并对相应污染源进行分析.结果表明第一主成分主要体现了水体中氮、磷等导致富营养化的关键因子,而第二个主成分主要反映水体重金属水平,整个江苏省太湖流域污染情况空间分布略有不同,水环境质量也大体表现为北高南低、西高东低的趋势,湖体也存在对应的空间特征,反映了流域外源输入是导致湖体水质污染的主要原因之一,为太湖流域的环境监测及污染治理提供重要的信息和依据.     

1989年3月特强磁暴期间的电离层暴

用欧亚大陆地面电离层垂测站资料考察1989年3月12～16日磁暴期间的电离层暴形态及其发展变化. 特强磁暴引发的电离层暴是全球性的,但自磁层沉降的高能粒子对热层低部的加热程度及区域分布不同,因而各经度链区域内电离层暴的特征也有所差异. 本文研究表明,与理论推断对照,欧洲地区内F2层最大电子密度NmaxF2(或f0F2)并不出现正暴现象,而负暴自高纬向低纬的发展则与典型的热层环流结果相符. 此外,此磁暴过程期间在中低纬区存在明显的波动过程. 在亚洲高纬地区,磁暴初期13日有约10 h的正暴,而负暴过程则与欧洲地区类似,但不太清晰;且无波动现象. 磁暴期间,同一经度链的中低纬地区,夜间常发生多站同时的h′F突增. 本文再次证实这是一般磁暴期间常出现的普遍现象.     

Temporal and spatial response of hyporheic zone geochemistry to a storm event

Although there has been recent focus on understanding spatial variability in hyporheic zone geochemistry across different morphological units under baseflow conditions, less attention has been paid to temporal responses of hyporheic zone geochemistry to non‐steady‐state conditions. We documented spatial and temporal variability of hyporheic zone geochemistry in response to a large‐scale storm event, Tropical Storm Irene (August 2011), across a pool–riffle–pool sequence along Chittenango Creek in Chittenango, NY, USA. We sampled stream water as well as pore water at 15 cm depth in the streambed at 14 locations across a 30 m reach. Sampling occurred seven times at daily intervals: once during baseflow conditions, once during the rising limb of the storm hydrograph, and five times during the receding limb. Principal component analysis was used to interpret temporal and spatial changes and dominant drivers in stream and pore water geochemistry (n = 111). Results show the majority of spatial variance in hyporheic geochemistry (62%) is driven by differential mixing of stream and ground water in the hyporheic zone. The second largest driver (17%) of hyporheic geochemistry was temporal dilution and enrichment of infiltrating stream water during the storm. Hyporheic sites minimally influenced by discharging groundwater (‘connected’ sites) showed temporal changes in water chemistry in response to the storm event. Connected sites within and upstream of the riffle reflected stream geochemistry throughout the storm, whereas downstream sites showed temporally lagged responses in some conservative and biogeochemically reactive solutes. This suggests temporal changes in hyporheic geochemistry at these locations reflect a combination of changes in infiltrating stream chemistry and hyporheic flowpath length and residence time. The portion of the study area strongly influenced by groundwater discharge increased in size throughout the storm, producing elevated Ca²⁺ and concentrations in the streambed, suggesting zones of localized groundwater inputs expand in response to storms. Copyright © 2013 John Wiley & Sons, Ltd.     

滇池流域点源污染控制与存在问题解析

滇池是我国著名的高原淡水湖泊,是国家"三河三湖"治理重点之一.对2007年滇池流域点源污染现状和近20年变化趋势进行了分析,并在此基础上解析了滇池流域点源污染存在问题.结果表明,2007年滇池流域点污染源COD.TN和TP产生量分别为55913t、11222t和1008t,生活污水为主要的点污染源,COD、TN、TP所占比例分别达89%、96%、98%;1988-2007年,流域点源污染负荷产生量持续增长,但由于1991年以来污水处理能力的大幅度提升,其后点源污染负荷总体上呈现下降的趋势,尤以COD和TP下降趋势最为明显,TN保持波动状态.滇池点源污染存在四方面问题,一是未来城市的扩张和人口的持续增长,势必给滇池水环境带来巨大压力;二是老城区合流制排水系统无法改变、新城区雨污管网混接、部分污水处理厂河道取水,导致雨季合流污水溢流污染问题长期存在;三是局部区域污水产生量与污水处理厂处理能力不匹配,且污水处理厂雨季处理能力不足;四是点源污染末端处理已不能满足滇池保护的要求,亟待加大污染全过程控制.     

Morphological response of a barrier island system on a catastrophic event: the AD 1634 North Sea storm

The AD 1634 North Sea storm is one of the most catastrophic storms along the Wadden Sea coast of Denmark. In this study we show how pre‐1634 storm morphology exerted a strong control on the resulting post‐storm coastal morphology. Erosional responses associated with the storm were barrier breaching, dune scarping and shoreface erosion and accretionary responses were washover deposition, shoreface healing and barrier‐island formation. Local sediment sources appeared to have a particularly strong influence on post‐storm coastal evolution and allowed a very rapid formation of a barrier shoal which resulted in several kilometres of coastal progradation. Sediment budgets suggest that formation of the barrier shoal was possible, but the sediment transport rates in the decades after the 1634 storm, must have been two to three times higher than present‐day rates. The study demonstrates that catastrophic storms are capable of moving large amounts of sediments over relatively short time‐periods and can create barrier shoals, whereas moderate storms mostly rework the shoal or barrier and create more local erosion and/or landward migration. Catastrophic storms substantially influence long‐term and large‐scale coastal evolution, and storms may positively contribute to the sediment budget and promote coastal progradation in coastal areas with longshore sediment convergence. Copyright © 2015 John Wiley & Sons, Ltd.