降水入渗补给过程的实验研究

根据河北保定冉庄实验站实测资料，描述了地下水深埋区降水入渗补给过程。通过1991年8m蒸渗仪实测资料，说明降水入渗过程中入渗锋面演变情况。地下水大埋深区包气带土壤含水量及降水入渗过程有以下3个特点：1包气带土壤含水量在垂向上具有分带的特点，从地表至1m为Ⅰ带，从地下水面至地下水面以上2m为Ⅲ带，介于Ⅰ带和Ⅲ带之间为Ⅱ带；2包气带土壤含水量具有季节性变化特征，包气带土壤含水量5月份最小，6～9月份较大：3降水入渗补给具有明显的滞后特征，从发生降水到该次降水对地下水入渗补给过程的结束，需要经历一个时程,包气带愈厚，时程愈长。     

降水补给地下水过程中包气带变化对入渗的影响

采用野外试验和室内试验方法，通过对不同降水量的入渗过程中岩土含水率和水势变化规律分析，发现入渗水流在包气带内下渗过程的岩土吸水、过水(即水分通量不变、且不等于零)和脱水的不同阶段，当岩土水势的梯度分别大于、等于和小于1cmH2O/cm(厘米水柱/厘米)时，岩土含水率分别表现为增加、稳定和减少。对包气带不同埋深的岩土含水率和水势变化特征分析表明，随着地下水位不断下降，包气带增厚对降水入渗补给地下水的影响程度和方式都发生改变。当包气带厚度小于潜水蒸发极限深度时，包气带的增厚使得岩土水分亏缺累积量增大，导致入渗速率和地下水获取的总入渗补给量减小；当包气带厚度大于潜水蒸发极限深度时，随着包气带厚度增大，入渗速率趋于稳定，无限时间内地下水获取的总入渗补给量不因包气带增厚而变化，但是有限时间内地下水获取的入渗补给量趋小。这是因为入渗途径的延长导致入渗所需时间增加，以至在有限时间内包气带内过剩的入渗水分尚未充分排出补给地下水。     

晋西南峨嵋台地地下水补给特征浅析

晋西南峨嵋台地地下水以下更新统深埋承压水为主，包气带岩性为中更新统的离石黄土，其主要的地下水补给源为大气降水。通过分析台地包气带岩性、黄土包气带湿度剖面、地下水位动态类型及黄土中的地裂缝等因素，阐述了离石黄土的结构、构造在塬区地下水补给过程中所起的重要作用；同时也说明了黄土中地裂缝的出现是峨嵋台地区新构造运动的继承和延续，进一步提出应把土的入渗理论发展为土体理论来研究。     

运用温度示踪法确定稳定入渗补给速率

开展不同水位埋深条件下的地中渗透仪入渗实验,分析包气带温度场变化规律及其控制因素,进而采用多层介质热传导解析方程评价入渗补给速率,探讨了温度示踪法评价包气带入渗补给问题的适用性。结果表明:气温控制包气带温度场整体特征,其对温度场的影响随深度增加逐渐减弱。水位埋深影响土壤含水率,控制包气带介质比热,决定了温度场波动性。灌水改变介质热导率从而影响包气带温度场;灌水量小且灌水温差小,灌水本身的热状态对温度场的影响可以忽略。水位埋深浅时,基于多层介质热传导解析方程的入渗补给速率评价结果更为准确,旱季相对雨季,评价结果准确性整体更高;浅部包气带含水率波动性强是造成评价误差的重要原因,选取更短的评价周期和更深的计算剖面可相对提高评价结果准确性。含水率在时间尺度上的波动是温度示踪法在非饱和带应用的难点及关键。     

VG模型参数对灌溉补给系数的敏感性分析

运用模型手段,计算灌溉补给系数时,VG模型中水力参数的不确定性严重影响了灌溉入渗补给系数的可靠性,且目前针对非均质岩土层入渗及其水力参数敏感性的研究较少。基于新疆伊犁霍城县原位试验场灌溉试验,运用HYDRUS-2D软件建立二维饱和-非饱和带水分运移数值模型,利用EFAST法和Morris筛选法分析了VG模型中水力参数对灌溉补给系数的敏感性,并分析比较两种方法的一致性。研究表明:当包气带岩性为均质结构时,θ_s(土壤的饱和含水率)及n(VG模型的形状参数)共同影响着灌溉补给系数。当包气带岩性处于上粗下细的结构时,θ_s对灌溉补给系数影响最大,即表明θ_s最为敏感,而且细颗粒θ_s相对于其他水力参数的耦合程度最大。n直接影响着土壤水分特征曲线的整体形状。同时EFAST法和Morris筛选法对参数敏感性分析结果呈现较高的相关性。由于VG模型中水力参数数量适中,EFAST法较Morris筛选法工作量合理,同时对模型参数敏感性分析更加贴近实际。研究成果对获取包气带水分运移模型参数有着重要意义。     

包气带垂向渗透系数的原位试验研究

野外试验测定包气带渗透系数对于研究非饱和带水分运移过程、植物根系吸水特征及产汇流规律具有重要意义。本文采用Inverse Auger法在毛乌素沙地开展了原位包气带垂向渗透系数测定实验。通过实验数据分析表明:①为获得较可靠的垂向渗透系数,野外实验时,需要重复注水过程,使包气带应尽可能湿润,消除水平吸渗对垂向入渗的影响;②采用Porchet推导的计算公式计算包气带垂向渗透系数时,应对获取的数据进行统计分析,放弃不符合实验物理背景的数据。在上述分析基础上,计算得到实验介质平均垂向渗透系数为2.23 cm/h。上述原位实验数据的分析方法和实验结果对相关实验研究具有一定的借鉴意义。     

VG模型参数对灌溉补给系数的敏感性分析

运用模型手段,计算灌溉补给系数时,VG 模型中水力参数的不确定性严重影响了灌溉入渗补给系数的可靠性,且目前针对非均质岩土层入渗及其水力参数敏感性的研究较少。基于新疆伊犁霍城县原位试验场灌溉试验,运用 HYDＲUS－2D 软件建立二维饱和－非饱和带水分运移数值模型,利用EFAST 法和 Morris 筛选法分析了 VG 模型中水力参数对灌溉补给系数的敏感性,并分析比较两种方法的一致性。研究表明: 当包气带岩性为均质结构时,θs( 土壤的饱和含水率) 及 n( VG 模型的形状参数) 共同影响着灌溉补给系数。当包气带岩性处于上粗下细的结构时,θs 对灌溉补给系数影响最大,即表明 θs 最为敏感,而且细颗粒 θs 相对于其他水力参数的耦合程度最大。n 直接影响着土壤水分特征曲线的整体形状。同时 EFAST 法和 Morris 筛选法对参数敏感性分析结果呈现较高的相关性。由于VG 模型中水力参数数量适中,EFAST 法较 Morris 筛选法工作量合理,同时对模型参数敏感性分析更加贴近实际。研究成果对获取包气带水分运移模型参数有着重要意义。     

包气带水分迁移离心模拟的可行性探讨

包气带水分运动是污染物运移及水、汽、热运动的主要驱动力,对于研究“四水”转换、地下水来源、水资源开发利用、生态保护及人类的生产生活都具有十分重要的意义。然而,能否将离心模拟应用于包气带水分迁移仍存在争议。通过建立离心场内一维包气带水分迁移的理论和数值模型,选用4套文献数据进行验证,探讨了将离心机用于包气带水分迁移的可行性。结果表明:①数值模型能够很好地重现文献中包气带水分迁移过程,与实验数据匹配较好;②分析物料守恒误差发现,当时间步长和空间步长取值都足够小时,数值模拟结果的质量能够保证为优秀;③离心模拟技术应用于包气带水分迁移是可行的;④离心模拟时加速度分布不均会导致模型底部的水分迁移滞后于原型,使用更高的离心加速度能够减轻这种现象。     

北京怀柔应急地下水源地降水入渗补给时滞性分析

华北平原目前普遍存在包气带增厚引起的地下水补给滞后问题,尤其是在地下水开采强烈地区。以北京怀柔应急地下水源地为研究区,利用交叉相关法(Cross-correlation)对研究区内的降水-水位进行了时滞性分析。研究发现,在2005年-2009年时段内,顺义河南村北河边观测井降水对地下水位的时滞时间为4～6个月;2009年的降水(421.8mm)没有产生超过95%可信度的响应系数,即无明显补给;在研究时间内,降水入渗补给主要与夏季(7月-9月)的降水有关,补给持续时间包括2005年11月-2006年2月、2006年12月-2007年1月、2007年12月-2008年1月、2008年10月-2009年1月,造成该降水补给的对应最大降水量分别为189.4mm(2005年8月)、200.6mm(2006年7月)、160.8mm(2007年7月)、699.5mm(2008年6月)。研究结果对水资源评价具有重要参考价值。     

大埋深条件下水文地质参数分析

利用水资源实验站的实验资料，通过分析非饱和带土壤水的运移规律，研究降水入渗补给机理等，确定大埋深条件下的水文地质参数。同时利用水文资料数据量大的特点，分析不同水文地质条件下的河道渗漏补给系数。     

SPATIAL AND TEMPORAL WATER QUALITY VARIABILITY IN AQUATIC HABITATS OF A CULTIVATED FLOODPLAIN

The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L^?1, the median total phosphorus was 0.29 mg L^?1 and the median total nitrogen was 1.56 mg L^?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.     

Spatio‐temporal variation of gross CO2 and CH4 diffusive emissions from Australian reservoirs and natural aquatic ecosystems,and estimation of net reservoir emissions

Carbon dioxide (CO₂) and methane (CH₄) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO₂ and CH₄ diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 10⁶ t CO₂eq km² per year, or 24 × 10⁶ t CO₂eq per year. This corresponds to a plant emission factor of 3.18 kg CO₂eq MWh^?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO₂eq per year, or 5.83 kg CO₂eq MWh^?1, which is in the lower range of the studied reservoirs.     

Serial discontinuities in a Rocky mountain river. II. Distribution and abundance of trichoptera

River regulation in the headwaters and middle reaches of the Gunnison River, Colorado, significantly altered distributions and abundances of Trichoptera fauna. Twenty-five species were collected from mainstream samples, with the greatest species richness occurring at an unregulated, rhithron segment above the central reach dams. At sites immediately below the three hypolimnial-release dams and a reregulation dam, species richness was reduced 35–90 per cent and abundance > 95 per cent. Net-spinning caddisflies were the dominant trichopterans at unregulated sites; Arctopsyche grandis in the upper reaches (218 organisms, 586 mg dry mass m^?2) and Hydropsyche cockerelli, H. occidentalis and Cheumatopsyche pettiti in the lower river (9041 total organisms, 6621 mg m^?2), downstream from the last dam. The observed distributional pattern of low trichopteran densities in dam tailwaters and high hydropsychid densities at sites 60–80 km below the central reach dams is a classic expression of continuum resets and adjustments in response to stream regulation as predicted by the Serial Discontinuity Concept.     

Surveying for Water Resources

Abstract

A professional Land Surveyor (Geomatician) describes the Hydrogeologists' survey requirements of a major water resources assessment for the government of The Sultanate of Oman (1992 to 1996). The need for objective specifications is stated. Specialist terms like geoid, spheroid, Mean Sea Level are explained and how to relate spheroidal levels to the geoid. Methods like traditional survey, satellite survey, and photogrammetry are introduced. The paper encourages coordinated working for the benefit of water resource assessment and recommends employment of the professional land surveyor for major studies.     

The Impact of Economic Development on Water Pollution: Trends and Policy Actions in Malaysia

The paper examines the impact of development activities on water pollution in Malaysia. Hence, the main objective of this paper is not just to examine the trends of development-induced water pollution around the region of the country but to know where the problems are and the policy measures taken by the government. It evaluates the probable causative relationship between problems introduced due to technology employed in water pollution control and governmental policy measures. It examines the relationship between development indicators as sources of pollution and polluted rivers over a period of 12 years. The findings of the paper have shown that despite the policy enforcement actions against the identified sources of water pollution, all the three development indicators (chosen based on those identified sources) still accounted for high percentage of river pollution in Malaysia. The findings of the paper were used to identify the central fact of the location of the problem. Some crucial conclusions of where the problems likely to be, as reflected in the findings, are: (a) the issue of interactive-effects between pollutants that many policy-makers are not aware of. This is when policy measures concentrate only on one source of water pollution; (b) the enforcement strength and/or effectiveness of policy measures themselves; (c) financial constraints to invest in appropriate technology especially sewerage systems for controlling human source of water pollution in the country; as well as those confronting small polluting industries (d) finally, lack of cooperation between government and private business firms to comply with regulatory policies for water pollution control.     

Intangible Flood Damage Quantification

Flooding is a natural disaster that may cause tremendous tangibleand intangible damage to the national economy. The tangible damage assessment, i.e. the monetary value of all direct and indirect physical damages, has already been studied, whileintangible damages have not yet been taken into account. Thisarticle, therefore, is the first systematic attempt to assess bothtangible and intangible damages. The new proposed Anxiety-Productivity and Income Interrelationgship Approach (API) has been developed to quantify the intangible damage in monetary terms. The Bangkok area has been selected as the research area because several severe flood events have occurredthere over the last two decades. The 1983 Bangkok flood caused 6600 million baht in damage, according to estimates by the National Statistical Office (NSO). This article examines the totalflood damage (including the intangible damage) at different flood magnitudes. Case studies with and without flood mitigation projects are studied and compared. Furthermore, thisarticle also discusses the improvements over the conventional approach offered by the new API methodology.     

Seasonal variation in nutrient retention during inundation of a short‐hydroperiod floodplain

Floodplains are generally considered to be important locations for nutrient retention or inorganic‐to‐organic nutrient conversions in riverine ecosystems. However, little is known about nutrient processing in short‐hydroperiod floodplains or seasonal variation in floodplain nutrient retention. Therefore, we quantified the net uptake, release or transformation of nitrogen (N), phosphorus (P) and suspended sediment species during brief periods (1–2 days) of overbank flooding through a 250‐m floodplain flowpath on the fourth‐order Mattawoman Creek, Maryland U.S.A. Sampling occurred during a winter, two spring and a summer flood in this largely forested watershed with low nutrient and sediment loading. Concentrations of NO increased significantly in surface water flowing over the floodplain in three of the four floods, suggesting the floodplain was a source of NO. The upper portion of the floodplain flowpath consistently exported NH, most likely due to the hyporheic flushing of floodplain soil NH, which was then likely nitrified to NO in floodwaters. The floodplain was a sink for particulate organic P (POP) during two floods and particulate organic N and inorganic suspended sediment (ISS) during one flood. Large releases of all dissolved inorganic N and P species occurred following a snowmelt and subsequent cold winter flood. Although there was little consistency in most patterns of nutrient processing among the different floods, this floodplain, characterized by brief inundation, low residence time and low nutrient loading, behaved oppositely from the conceptual model for most floodplains in that it generally exported inorganic nutrients and imported organic nutrients. Published in 2007 by John Wiley & Sons, Ltd.     

浅淡溢洪道改扩建方案与选择

溢洪道改扩建和进行溢洪道方案布置，要择优选取溢洪道进口型式、防冲消能工，以使其工程量省、施工快、运行管理方便     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Experience in the Introduction of Steam-Water-Oxygen Cleaning, Passivation, and Preservation at the TÉTs-23 Cogeneration Plant of the Mosénergo Company

Conditions of the process of steam-water-oxygen cleaning, passivation, and conservation (SWOC, P, and C) of internal heating surfaces of the boiler and the high-pressure feed heater (HPFH) piping over the steam side are presented. The process produces partial cleaning of the internal heating surfaces from scale and yields a corrosion-resistant protective film that hinders corrosion processes both in the operation of the boiler and in the idle period.