Hydrological regime of Lake Bol’shoi Tambukan

The results of studying the hydrological regime of Lake Bol’shoi Tambukan and its catchement are discussed; the data reveal higher total evaporation from forest plantings in comparison with evaporation from other land areas of the catchment. A close relationship was shown to exist between the lake water level and humidity factor of the surrounding area; it was most contrasting during the four-year period when the water level rose by 2.5 m and caused critical environmental situation in the water body. Over the period of 33 years, water supply to the lake ruled out its natural sterilization. The need to regulate the lateral inflow into the lake with regard to the volume of man-made water supply was shown.     

Modelling evaporation processes in soils from the Huasco salt flat basin,Chile

The need to understand and simulate hydrological phenomena and their interactions, and the impact of anthropogenic and climate changes on natural environments have promoted the study of evaporation from bare soils in arid climates. In closed Altiplano basins, such as those encountered in arid and hyper arid basins in northern Chile, evaporation from shallow groundwater is the main source of aquifer depletion, and thus, its study is crucial for water resources management. The objective of this work is to understand the mechanisms of evaporation in saline soils with shallow water tables, in order to better quantify evaporation fluxes and improve our understanding of the water balance in these regions. To achieve this objective, a model that couples fluid flow with heat transfer was developed and calibrated using column experiments with saline soils from the Huasco salt flat basin, Chile. The model enables determination of both liquid and water vapour fluxes, as well as the location of the evaporation front. Experimental results showed that salt transport inside the soil profile modified the water retention curve, highlighting the importance of including salt transport when modelling the evaporation processes in these soils. Indeed, model simulations only agreed with the experimental data when the effect of salt transport on water retention curves was taken into account. Model results also showed that the evaporation front is closer to the soil surface as the water table depth reduces. Therefore, the model allows determining the groundwater level depth that results in disconnection of liquid fluxes in the vadose zone. A sensitivity analysis allowed understanding the effect of water‐flux enhancements mechanisms on soil evaporation. The results presented in this study are important as they allow quantifying the evaporation that occurs in bare soils from Altiplano basins, which is typically the main water discharge in these closed basins. Copyright © 2016 John Wiley & Sons, Ltd.     

Design and Implementation of Evapotranspiration Measuring Equipment for Owens Valley, California

As part of a plant survivability and ground water study in Owens Valley, California, semipermanent installations are used to measure continuous range-land evapotranspiration in the valley's phreatophyte community. A proposed mobile installation also has been designed. The semipermanent micrometeoro-logical station collects continuous data for solution of the Bowen ratio/energy budget equation and the Penman combination equation. Three sites were chosen for this type of installation to provide a representative sampling of Owens Valley. The proposed mobile aerodynamic installation should be capable of calculating evapotranspiration by the eddy correlation method. This instrumentation will be used throughout the valley for short periods of time (up to five days). Many problems with equipment operation, calibration and design have been identified and resolved by means of improved calibration techniques, systematic error-removal techniques, reduced cycle times, modified equipment design and proper observer training. The collected evapotranspiration data will be instrumental in developing a one-dimensional evapotranspiration flux algorithm for a model of valleywide ground water flow.     

River evaporation and corresponding heat fluxes in forested catchments

River water temperature is a very important variable in ecological studies, especially for the management of fisheries and aquatic resources. Temperature can impact on fish distribution, growth, mortality and community dynamics. River evaporation has been identified as an important heat loss and a key process in the thermal regime of rivers. However, its quantification remains a challenge, mainly because of the difficulty of making direct measurements. The objectives of this study were to characterize the evaporative heat flux at different scales (brook vs river) and to improve the estimation of the evaporative heat flux in a stream temperature model at the hourly timescale. Using a mass balance approach with floating minipans, we measured river evaporation at an hourly timescale in a medium‐sized river (Little Southwest Miramichi) and a small brook (Catamaran Brook) in New Brunswick, Canada. With these direct measurements of evaporation, we developed mass transfer equations to estimate hourly evaporation rates from microclimate conditions measured 2 m above the stream. During the summer 2012, river evaporation was more important for the medium‐sized river with a mean daily evaporation rate of 3.0 mm day^?1 in the Little Southwest Miramichi River compared with that of 1.0 mm day^?1 in Catamaran Brook. Evaporation was the main heat loss mechanism in the two studied streams and was responsible for 42% of heat losses in the Little Southwest Miramichi River and 34% of heat losses in Catamaran Brook during the summer. Copyright © 2013 John Wiley & Sons, Ltd.     

VALENCIA LAKE AS A HYDROLOGICAL INDICATOR 1901–62

Abstract

Valencia Lake, in northern Venezuela, and its tributary area (the catchment is approximately seven times larger than the lake which has an area of about 350 km²) are completely isolated from any river system or sea. The lake is about 400 m above sea level, and the adjacent ranges are up to 2,000 m higher. Observations of the fluctuations of the lake level since 1901 exist (with sporadic data since 1700), along with data on rainfall in the watershed and near the lake for the same period of time. Since 1939, 21 mostly small, tributary rivers have been hydrologically controlled. Evaporation (class A pan) has been observed also during this time. Since the tributary Rivers dry out for severall months each year, the lake descends as a function of its evaporation and serves as a large evaporation pan. The mean annual value is about 2,000 mm. By balancing losses (evaporation) against gains (runoff plus direct rain on the lake) a “hydrological pattern” was developed for the 61 years of fluctuation record; it was rechecked the last 22 years using the additional data. Yearly percentages as a function of the average were calculated.     

Recent changes in the level of Lake Abiyata,central main Ethiopian Rift

Abstract

The spatial and temporal variations in the level of Lake Abiyata and controlling natural and manmade factors are presented. This study has been made by combining evidence from hydrometeorological and lake level records, water budget analyses, aerial photograph and satellite imagery interpretations, and numerical groundwater flow modelling. The most important components of the water balance of the lake are precipitation, river inflow and evaporation. The lake level has been fluctuating considerably over a wide range (by 6 m during the last 60 years) strongly controlled by the precipitation trends in the adjacent highlands. Climatic changes and consequent reduction in the surface water inputs have resulted in the reduction of its size. Recent abstraction of water for irrigation and soda ash production have drastically changed both the lake level and its hydrochemistry. This change appears to have grave environmental consequences on the fragile rift lacustrine ecosystem.     

Evidence for Elevated Levels of Arsenic in Public Wells of Bangladesh Due To Improper Installation

One of the mainstays of mitigation to reduce the exposure of the rural population of Bangladesh to arsenic (As) from private, mostly <90‐m deep wells over the past 15 years has been the installation of over 300,000 deeper community wells. A comprehensive testing campaign previously conducted across a 180 km² of area of Bangladesh identified 9 out of total of 927 wells >90 m deep that contained >50 µg/L arsenic. We show here that for five of these nine wells, conductivity profiles obtained after spiking the well bore with salt indicate a shallow leak that could explain the high As in the well water. In two of the five leaky wells, the presence of additional screens at the depth of the leak was documented with a downhole camera. The downhole camera did not detect anomalies in the construction of the remaining three leaky wells or in the four wells that did not leak. The four wells that did not leak were all >150‐m deep and located in two villages separated by less than 500 m. Excluding these two villages and a handful of leaky wells, the results indicate an aquifer that is consistently low in As over a sizeable area at depths >90 m. Isolated cases of public wells that are elevated in As that have been reported elsewhere in Bangladesh may therefore reflect improper installation rather than actual contamination of the deep aquifer.     

The impact of organic material on cloud and fog processes

Airborne surface-active organic substances can form adsorbed films at air-water and air-solid interfaces in the atmosphere. On the basis of considerable laboratory research, it has been suggested that these films can modify the microphysical processes of clouds and fog. The possible alterations of physical processes include retardation of the rate of growth and evaporation of water drops, passivation of cloud condensation nuclei, modification of drop coalescence efficiency, and the promotion of drop instability. The chemical structure of the film-forming compounds and the physical properties of the adsorbed films determine the degree to which the physical processes are modified. Upon consideration of the actual organic composition of the atmosphere, it was concluded that natural surface films will not greatly influence drop growth and evaporation. In addition, there is no definitive evidence from field experiments that other processes are influenced by natural organic films. The potential for useful weather modification through the intentional introduction of film-forming organic substances into the atmosphere was critically evaluated. Although numerous approaches have been suggested by laboratory studies, only the stabilization of airborne drops against evaporation has been unequivocally demonstrated in field experiments.     

宽频带流动地震台站中地震计浅井式安装研究

在井下地震观测中,各种地表背景噪声具有显著衰减作用,针对中国地震科学台阵现有大量非专用浅井式设计的Guralp CMG系列地震计,以及目前多个新获批项目在高背景噪声区域的观测需求,设计一种野外实用浅井观测方式,在北京国家地球观象台进行不同深度、不同井壁材质的观测对比实验,分析研究观测数据的背景噪声功率谱密度,结果表明,随着浅井深度的增加,地震背景噪声在垂直、水平向得到改善,改善程度随频率变化有所不同。分析认为,在华北现有地质环境下,6 m浅井是较为经济的观测方式,性价比高、占地小、施工简便,可用于后续多个项目的宽频带流动地震台阵观测。     

KFD——宽频带大动态反馈地震计的设计和性能

我们设计了一种便携式的宽频带反馈地震计,并与标准长周期地震计(763)及力平衡式宽频带反馈地震计(STS-1V,STS-1H)作了比较,并在不同干扰环境及工作条件下进行了考验.结果是令人满意的.地震计由一台垂直向和两台水平向组成.其惯性质量为0.8kg,自然机械振动周期为15s(秒),机械品质因素约为50.用一差动电容位移换能器将惯性质量的位移变化转变成电信号,而加于电磁系统的反馈使质量维持在它的平衡位置附近.该仪器在其通带范围内具有平坦的位移频响特性.这由反馈网络决定,它相当于一个具有30s 自然周期的位移传感长周期(LP)地震计加上截止频率为0.03s 的二阶低通滤波器系统.该仪器的动态范围为100dB,阻尼为0.8.设计中着重考虑便携性,安装方便以及对环境干扰的有效屏蔽及低功耗.      

鄱阳湖夏季水面蒸发与蒸发皿蒸发的比较

水面蒸发是湖泊水量平衡要素的重要组成部分.基于传统蒸发皿观测蒸发不能代表实际水面蒸发,而实际水面蒸发特征仍不清楚.本研究基于涡度相关系统观测的鄱阳湖水体实际水面蒸发过程,在小时和日尺度分析了水面蒸发的变化规律及其主要影响因子,并与蒸发皿蒸发进行比较.研究表明,实际水面蒸发日变化波动剧烈,变化范围在0~0.4 mm/h之间.水面蒸发的日变化特征主要受风速的影响.鄱阳湖8月份日水面蒸发量与蒸发皿蒸发量在总体趋势上具有很好的一致性.8月份平均日水面蒸发速率(5.90 mm/d)比蒸发皿蒸发速率(5.65 mm/d)高4.6%.水面日蒸发量与蒸发皿蒸发量的比值在8月上、中、下旬平均值分别为1.24、1.00、0.92,呈现下降的趋势.鄱阳湖夏季水面日蒸发量与风速和相对湿度相关性显著,而蒸发皿蒸发与净辐射、气温、饱和水汽压差和相对湿度均呈显著相关.这是由于蒸发皿水体容积小,与湖泊相比其水体热存储能力小,因此更容易受到环境因子的影响.     

Potential and visible evaporation and its variations in European Russia over the recent 50 years by experimental data

Variations in pan evaporation in European Russia from 1951 to 2010 have been studied, and regions with specific variations of potential evaporation have been identified. It is shown that evaporation decseases all over the territory under consideration, and intensity of its decreasing up to the late 1970s was far in excess of that in the decades that followed. The decrease in the variations in evaporation may be regarded as an indicator of reduction of intensity of heat and moisture exchange between the underlying surface and the atmosphere. A new characteristic of the moisture regime of the territory, i.e., visible evaporation, was introduced to characterize, in this case, the amount of free moisture in the atmosphere that can be involved in the terrestrial water cycle. The humidity of the territory in the European Russia has shown to have increased since 1966. Regions where changes in the moisture regime show common patterns have been identified and the specific features of humidity distribution in different natural zones of European Russia have been assessed.     

山东大山地震台避雷器简介

介绍了一种适合于地震台站地震仪器使用的避雷器,叙述了其工作原理,安装方法,指出因其造价低廉、安装简单、安全可靠,可保证地震仪器的正常运转。     

A recharge model for high altitude,arid, Andean aquifers

Evidence for groundwater recharge in arid zones is mounting, despite early ideas that recharge was unlikely where evaporation greatly exceeded precipitation. The mechanisms and magnitude of groundwater recharge in the Andes and Atacama Desert are not well known but the subject of current research. Diffuse recharge is expected to be limited to high altitude areas with coarse‐grained soils devoid of vegetation. A recharge model for this environment is developed based on a simple soil moisture budgeting technique and the calculation of actual evaporation based on empirical studies. The model is run with data for the Linzor basins, over 4000 m elevation at 22·2°S on the west slope of the Andes. It is checked against independent estimates based on the chloride mass balance (CMB) method and flood events measured downstream in the Río Salado and found to provide robust and reliable results. The results indicate that irregular and volumetrically limited amounts of diffuse recharge occur at high elevations in half of all years, with a tendency to cluster during La Niña episodes. For the Linzor Basins, mean annual recharge is found to be equivalent to 28 mm a^?1, although no recharge occurs in years with precipitation less than 120 mm, and increases proportionately with annual rainfall amounts above this limit. Copyright © 2009 John Wiley & Sons, Ltd.     

A water-budget approach to restoring a sedge fen affected by diking and ditching

A vast, ground-water-supported sedge fen in the Upper Peninsula of Michigan, USA was ditched in the early 1900 s in a failed attempt to promote agriculture. Dikes were later constructed to impound seasonal sheet surface flows for waterfowl management. The US Fish and Wildlife Service, which now manages the wetland as part of Seney National Wildlife Refuge, sought to redirect water flows from impounded C-3 Pool to reduce erosion in downstream Walsh Ditch, reduce ground-water losses into the ditch, and restore sheet flows of surface water to the peatland. A water budget was developed for C-3 Pool, which serves as the central receiving and distribution body for water in the affected wetland. Surface-water inflows and outflows were measured in associated ditches and natural creeks, ground-water flows were estimated using a network of wells and piezometers, and precipitation and evaporation/evapotranspiration components were estimated using local meteorological data. Water budgets for the 1999 springtime peak flow period and the 1999 water year were used to estimate required releases of water from C-3 Pool via outlets other than Walsh Ditch and to guide other restoration activities. Refuge managers subsequently used these results to guide restoration efforts, including construction of earthen dams in Walsh Ditch upslope from the pool to stop surface flow, installation of new water-control structures to redirect surface water to sheet flow and natural creek channels, planning seasonal releases from C-3 Pool to avoid erosion in natural channels, stopping flow in downslope Walsh Ditch to reduce erosion, and using constructed earthen dams and natural beaver dams to flood the ditch channel below C-3 Pool. Interactions between ground water and surface water are critical for maintaining ecosystem processes in many wetlands, and management actions directed at restoring either ground- or surface-water flow patterns often affect both of these components of the water budget. This approach could thus prove useful in guiding restoration efforts in many hydrologically altered and managed wetlands worldwide.     

Application of non‐linear multiple tuned mass dampers to suppress man‐induced vibrations of a pedestrian bridge

This paper presents an application of multiple tuned mass dampers (MTMDs) with non‐linear damping devices to suppress man‐induced vibrations of a 34m long pedestrian bridge. The damping force generated by each of these damping devices is simply a drag force from liquid acting on an immersed section. The quadratic non‐linear property of these devices was directly determined from free vibration tests of a simple laboratory set‐up. Dynamic models of the bridge and pedestrian loads were constructed for numerical investigation based on field measurement data. The control effectiveness of non‐linear MTMDs was examined along with its sensitivity against estimation errors in the bridge's natural frequency and magnitude of pedestrian load. The numerical results indicated that the optimum non‐linear MTMD system was as effective and robust as its linear counterpart. Then, a six‐unit non‐linear MTMD system was designed, constructed, and installed on the bridge. Field measurements after the installation confirmed the effectiveness of non‐linear MTMDs, and the measurement results were in good agreement with numerical predictions. After the installation, the average damping ratio of the bridge was raised from 0.005 to 0.036 and the maximum bridge accelerations measured during walking tests were reduced from about 0.80–1.30 ms^?2 to 0.27–0.40 ms^?2, which were within an acceptable range. Copyright © 2003 John Wiley & Sons, Ltd.     

太湖群体微囊藻对同形溞(Daphnia similis)生长和繁殖影响的模拟

富营养湖泊中蓝藻水华对枝角类种群和群落结构有显著的影响,但自然条件下群体微囊藻对大型枝角类溞属不同种类的影响仍存在争议.本研究通过两次为期各10 d的模拟实验,利用过滤后的太湖原水模拟群体微囊藻(20～100μm和100 ～200 μm)添加对大型枝角类同形溞(Daphnia similis)种群特征的影响,结果显示两次实验的同形溞均大量存活,不同浓度和颗粒大小的群体微囊藻对其生长和繁殖的影响不同,添加群体微囊藻的同形溞的生长和繁殖显著大于未添加微囊藻的.说明在自然条件下藻毒素对同形溞种群并没有明显的抑制作用,同形溞能够与微囊藻水华共存,其种群特征与微囊藻群体大小组成和生物量有关.     

Quantifying evaporation in a permeable pavement system

Studies quantifying evaporation from permeable pavement systems are limited to a few laboratory studies and one field application. This research quantifies evaporation for a larger field application by measuring the water balance from lined permeable pavement sections. The U.S. Environmental Protection Agency constructed a 0.4 ha parking lot in Edison, NJ, that incorporated three different permeable pavement types in the parking lanes – permeable interlocking concrete pavers (PICP), pervious concrete (PC) and porous asphalt (PA). An impermeable liner installed 0.4 m below the surface in four 11.6 m by 4.74 m sections per each pavement type captures all infiltrating water and routes it to collection tanks that can contain events up to 38 mm. Each section has a design impervious area to permeable pavement area ratio of 0.66:1. Pressure transducers installed in the underdrain collection tanks measured water level for 24 months. Level was converted to volume using depth‐to‐volume ratios for individual collection tanks. Using a water balance approach, the measured infiltrate volume was compared to rainfall volume on an event basis to determine the rainfall retained in the pavement strata and underlying aggregate. Interevent evaporation created additional storage in the pavement and aggregate layers. Events were divided into three groups based on antecedent dry period (ADP) and three 4 month groups of potential evaporation based on historical monthly pan evaporation records. There was a significant difference in rainfall retained among the various combinations of ADP and potential evaporation groups. More rainfall was retained in the pavement and aggregate layers as time between events increased and during warmer months with larger potential evaporation. Average cumulative evaporation from the permeable pavement sections for 134 rainfall events in 24 months was 5.2% of the cumulative rainfall volume, and the range was 2.4–7.6%. Each PC section had more annual evaporation than any individual PICP or PA section. While measureable, evaporation is a small contribution to the total water budget on an annual basis for these systems. Copyright © 2014 John Wiley & Sons, Ltd.     

An automated tunnel evaporation measurement system for confined spaces

An automated tunnel evaporation‐rate measurement system (TEMS) has been designed to measure automatically the evaporation from a cylinder 0·30 m in diameter and ～0·10 m tall. This cylinder continuously maintains a constant height of water, with losses to evaporation replenished from a stilling cylinder connected to a water reservoir. The evaporation rate is measured by a transducer located at the bottom of the stilling well. The TEMS was tested over a period of 3 months in an underground research facility with relatively strong wind effects, changing temperature, and changing humidity. During this period, the TEMS continued to function uninterrupted, automatically measuring the evaporation amounts along a tunnel and an enclosed niche. These observations suggest that this tool can be useful for investigations of evaporation processes both in enclosed and ventilated environments. Published in 2002 by John Wiley & Sons, Ltd.