洋河水库富营养化限制性因子分析

以洋河水库2001~2005年的监测资料为基础,运用回归统计方法,选择水温等8项环境理化指标与藻类叶绿素a进行回归分析。结果显示,总磷、水温、pH值和透明度与藻类叶绿素a呈显著相关,其中总磷和水温是洋河水库富营养化限制性因子。根据2003~2005年水库监测资料,建立多元逐步回归方程,预测水库藻类叶绿素a的变化情况。运用该回归方程,计算水库2001~2002年藻类叶绿素a变化情况并与实测值作比较,结果表明,该方程能基本预测洋河水库藻类叶绿素a的变化趋势。     

Optimal Allocation of Monthly Water Withdrawals in Reservoir Systems

In this study, a water balance equation was derived and theperformance of a project was analyzed. The water balancecomponents were modeled without calibration, and compared withmeasured data, whenever possible. A reservoir simulation modelwas develop and the model storage capacities were compared withthe observed storage capacities satisfactorily. An optimizationmodel was developed to solve the water resources of a largeproject in a computationally satisfactory manner. The optimalreservoir storage, optimal irrigation demand, and optimalreservoir release were computed. The optimal mean (1987–1997)model total water requirements for the dry and wet seasons werealso computed and the optimal contributions by rainfall,reservoir, uncontrolled river flow, and recycled water weredetermined. The mean annual optimal water withdrawals from thereservoir systems were found to be 1223 MCM (Million cubicmeters). The optimal mean model total water requirements werecompared with other authors computed values for the same and asignificant water savings was achieved.     

Horizontal displacements of rock foundations of dams

Conclusions Horizontal displacements of rock foundations toward the lower pool are small and even for high (100 m and more) dams in narrow and wide sites do not exceed 15–20 m. Ths displacements rapidly die away with depth and at 10–15 m from the contact decrease by almost an order, and lower the displacements of rocks toward the upper pool as a consequence of deflection of the reservoir bed can predominate. Filling of the reservoir led to the divergence or convergence of the banks. In the majority of cases convergence was observed, including in the case of gently sloping banks. The movements affected points located more than 100 m into the banks.Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 2, pp. 42–45, February, 1987.     

基于多波段遥感数据的库区水深反演研究

遥感反演是一种水深量测新方法,应用在库区水深量测对水库运行调度、库区淤积研究等均有着积极的作用。针对统计相关分析法中单点量测水深值代表遥感像元对应水深值这一缺陷,本文提出使用同像元多测点数据表征像元对应水深值的方法。以内蒙古海勃湾水库为研究区域,通过表征水深值与各波段组合的相关性选取水深反演因子,建立线性、二次、指数3种形式15组双波段模型与5组不同个数反演因子的多波段模型,从中遴选出较优的5个反演模型,使用未参与建模的检查点样本进行模型精度检验,通过检验结果进行模型比对。结果表明:海勃湾水库水深反演最优反演模型是由12个反演因子建立的多波段反演模型,其平均绝对误差为0.68 m,占平均水深的13.59%。结合遥感周期短、成本低的特点,该方法在一定程度上可以应用于实际,但泥沙含量大与靠近陆地的水域水深反演效果较差。     

RETRIEVING RIVER ATTRIBUTES FROM REMOTELY SENSED DATA: AN EXPERIMENTAL EVALUATION BASED ON FIELD SPECTROSCOPY AT THE OUTDOOR STREAM LAB

This paper summarizes experiments conducted at the Outdoor Stream Lab to gain insight on the relationships between a channel's spectral characteristics and the river attributes of interest to scientists and managers. Improved understanding of these connections would advance the application of remote sensing to fluvial systems. Motivated by this objective, we examined the following: (i) interactions among local hydraulics, water surface roughness and surface reflectance; and (ii) the influence of periphyton development and streambed disturbance on bottom reflectance. These experiments could thus lead to novel methods for inferring flow velocity and substrate type, respectively, from passive optical image data. Our initial results indicate the following: (i) water surface reflectance can compromise spectrally based depth retrieval by reducing the range of useful wavelengths and weakening correlations between band ratios and depth, implying that removing the surface‐reflected component of the total radiance could facilitate bathymetric mapping; (ii) water surface roughness was influenced by local hydraulics and was positively correlated with water surface reflectance, suggesting that observations of surface reflectance could be used to infer flow velocities; (iii) substrate spectral characteristics were influenced by the degree of periphyton development, implying that algal biomass might be estimated from remotely sensed data; and (iv) similarly, bottom reflectance differed significantly for intact versus disturbed substrates, suggesting that areas of streambed disturbance might be identified via remote sensing. Future work will focus on further elucidating connections between surface reflectance, water surface texture and flow velocity, and developing quantitative relationships between bottom reflectance, periphyton abundance and the degree of streambed disturbance. Copyright © 2013 John Wiley & Sons, Ltd.     

Trends in Water Clarity of the Lower Great Lakes from Remotely Sensed Aquatic Color

Satellite observations of aquatic colour enable environmental monitoring of the Great Lakes at spatial and temporal scales not obtainable through ground-based monitoring. By merging data from the Coastal Zone Color Scanner (CZCS) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), monthly binned images of water-leaving radiance over the Great Lakes have been produced for the periods 1979–1985 and 1998–2006. This time-series can be interpreted in terms of changes in water clarity, showing seasonal and inter-annual variability of bright-water episodes such as phytoplankton blooms, re-suspension of bottom sediments, and whiting events. Variations in Secchi disk depth over Lakes Erie and Ontario are predicted using empirical relationships from coincident measurements of water transparency and remotely-sensed water-leaving radiance. Satellite observations document the extent to which the water clarity of the lower Great Lakes has changed over the last three decades in response to significant events including the invasion of zebra mussels. Results confirm dramatic reductions in Lake Ontario turbidity in the years following mussel colonization, with a doubling of estimated Secchi depths. Evidence confirms a reduction in the frequency/intensity of whiting events in agreement with suggestions of the role of calcium uptake by mussels on lake water clarity. Increased spring-time water clarity in the eastern basin of Lake Erie also corroborates previous observations in the region. Despite historical reports of localised increases in transparency in the western basin immediately following the mussel invasion, image analysis shows a significant increase in turbidity between the two study periods, in agreement with more recent reports of longer term trends in water clarity. Through its capacity to provide regular and readily interpretable synoptic views of regions undergoing significant environmental change, this work illustrates the value of remotely sensing water colour to water clarity monitoring in the lower Great Lakes.     

Detection of Extent of Sea Level Rise in a Coastal Lake System using IRS Satellite Imagery

Coastal lakes are often under the threat of sea water ingress causing the depletion of fresh water bodies. Salinization due to sea water ingress causes impact on water resources especially in coastal areas. Thus there is scarcity of fresh water in this region. Climate change causes rise in sea level and this leads to increase of salinity in coastal lakes. Satellite imagery analysis now plays a prominent role in the quick assessment of water quality in a vast area. This study is an attempt to assess the extent of a lake system affected by sea water (Akkulam-Veli lake, Kerala, India) using Indian Remote Sensing Satellite, IRS P6 LISS III imagery. Field data were collected on the date of the satellite overpass. Simple regression equation using radiance in red band is found to yield superior results for the prediction of sodium content whereas polynomial equation using radiance of red band is found to yield superior results for the prediction of chloride content than the simple and multiple regression equations using spectral ratios and radiance from the individual bands from satellite imagery. The refractive index of water containing sodium chloride is more when compared with that of fresh water and this in turn results in high reflection of visible light in the red band when compared to blue and green bands. Hence the radiance of red band gives direct measure of sodium and chloride in lake water. IRS P6-LISS III imagery can be effectively used for the assessment of sea water affected area of the lake system.     

Estimation of siltation of the Tereblya-Rika hydroelectric station reservoir

Conclusions An estimation of the suspended-load discharge with the use of the existing data of hydrological yearbooks was not very reliable, since it gave quite underestimated results of the calculation in comparison with the actual volumes of siltation of the reservoir.The bed-load discharge calculated on the basis of data on the migration of meso-forms and a detailed analysis of the actual maximum runoff hydrographs of the Tereblya River, characterized by the transport of channel-forming sediments, is in good agreement with the data of the particle-size analysis of the reservoir siltation products and amounts to not more than 1% of the total sediment load.On the basis of a statistical analysis of the data of field observations, a lognormal relation was established between the volumes of water and sediment discharges, reflecting in a most generalizing form the main characteristics of fluvial processes of streams in the investigated region.With consideration of the substantial changes in the morphometric characteristics of the reservoir, it is economically advisable to change to the use of refined depth curves.Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 7, pp. 47–50, July, 1988.     

Water level fluctuation and sediment–water nutrient exchange in Great Lakes coastal wetlands

The influence of water level fluctuation on sediment–water nutrient exchange in coastal wetlands of Lakes Michigan and Huron was investigated using controlled, laboratory experiments. At each wetland, sediment cores were collected from 5 locations along a transect perpendicular to the shoreline, desiccated for 8 weeks, and then re-wetted with original site water for 24 h to simulate water level fluctuation. Soluble reactive phosphorus release declined exponentially along transects, with highest release rates from sediments collected at the ordinary high water mark (OHWM), and lowest rates from sediments underlying water > 0.25 m in depth. Nitrate exchange showed no obvious pattern in the Lake Michigan wetlands but nitrate was lost at all locations in the Lake Huron wetlands, suggesting denitrification. Ammonium was released at all sites, but with no obvious pattern along transects. Sulfate release was low at the OHWM locations and increased in a lakeward direction, plateauing by the 0.25 m water depth.     

Experience in compacting backfill during construction of the Dnepr-Donbas canal

Conclusion The results of the tests showed that the scheme used for compacting the backfill can be used effectively when it is necessary to compact water-saturated sand soils to a depth up to 5 m.Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 6, pp. 18–19, June, 1988.     

The Influence of Natural and Human-Related Factors on the Water Circulation in the Carpathian Foothills (southern Poland)

Part of the northern Carpathian Mountains, the flysch-built Carpathian Foothills form a low-mountain area (300–500 m) with dense population and intensive farming. Here, in 1981–1995, a water circulation research project was conducted in the Wierzbanówka catchment basin (11.7 km²), a typical catchment basin of this land. The Carpathian Foothills are characterised with a relatively high fluctuation in the activity of the underground water effluents (outflow), ground water level and watercourse discharge. This is a result of the area's irregular precipitation patterns, low water penetrability of the ground, low underground and surface water retention and of the terrain gradients and the complex relief. The high rate of the water circulation is also a result of the dominance of the agricultural use of land (60–80% of the total area), low forest coverage (10–30%) and the inadequate water resource management. Possible actions aiming to reduce the dynamics of the water circulation in this area should include the following: turning of a portion of the existing farmland into forestland, boosting the area of pastures and meadows, restoration of the natural character of river channels and valley bottoms, reinstating certain small water management facilities (ponds, dykes, etc.).     

Water table dynamics of Dhaka city and its long-term trend analysis using the “MAKESENS” model

The water table (WT) data of Dhaka city for 17 years (1988–2004) was analysed for assessing WT fluctuation and predicting its trend using a computer model, “MAKESENS”. The analysis revealed that the WT declined drastically at different locations of the city. Moreover, the model also predicted that WT would further decline 9–25 m by the year 2015 and 18–40 m by the year 2025, rendering most wells inoperative, if the pumping rate was not reduced.     

Influence of hydrology on water quality and trophic state of irrigation reservoirs in Sri Lanka

Many reservoirs provide multiple benefits to people around the world, in addition to primary uses such as irrigation. Thus, reservoir management should address their multiple uses. The water quality of ten irrigation reservoirs in Sri Lanka was examined in the present study with the objective of better understanding the effects of hydrological regimes on reservoir water quality and trophic state. Basic limnological parameters pertinent to the nutrient loads to, and trophic state of, the reservoirs were collected from June 2013 to February 2016. The sampling period was arbitrarily divided into two periods of approximately similar duration (period 1 = June 2013–September 2014; period 2 = October 2014–February 2016) to investigate whether or not there was a seasonal variation in the water quality parameters. Although temporal and spatial variations were observed, most water quality parameters were within the levels acceptable for drinking water standards. The 10 reservoirs were also ordinated by principal component analysis (PCA) on the basis of the water quality parameters of the two sampling periods in a two‐dimensional score plot. Reservoirs in the first principal component (PC1) axis were represented by negative scores attributable to the dissolved oxygen concentration and pH and, to a lesser extent, by electrical conductivity and chlorophyll‐a concentration. Positive scores in PC1 were represented by reservoirs with a score loading attributable to alkalinity, nitrate concentration, Secchi depth, temperature and seston weight and, to a lesser extent, from the total phosphorus concentration. There was a significant negative correlation of PC1 scores with relative reservoir water‐level fluctuation (RRLF; the ratio of mean reservoir water‐level amplitude to mean reservoir depth). Furthermore, Carlson's trophic index also were influenced by RRLF, although not by hydraulic retention time (HRT), indicating allochthonous nutrient inputs into the irrigation reservoirs were mainly governed by RRLF, but not by HRT. Thus, the results of the present study provide useful insights into achieving desirable reservoir water quality through the manipulation of the hydrological regime.     

Design and watertight effectiveness of the underground contour of the Sayano-Shushenskoe dam

Conclusions Seepage in the foundation of the SSh hydrostation has a nonuniform but regular character and substantially depends on the acting head and SSS. At an elevation of the UPL of less than 520 m, a change in the permeability of the rock mass is observed mainly on the upstream side of the grout curtain. The intensity of decompression of the rocks increases with increase of elevation of the UPL, especially above 534 m. At 540 m the zone of decompression of the contact part of the foundation in some places intersects the grout curtain and in individual cases intercepts the drainage; the discharge of the drain wells increases by 5–7 times in comparison with the discharge at an elevation of the UPL of 500 m. The width of the joints near the drainage (according to calculation) averages from 0.3–0.5 to 0.73 mm; here and there it can reach 1.5–2 mm. The average gradient of the head in the grout curtain is within 10–15; at individual places near the drainage it reaches 26, which is at the level of the allowable for a rock mass.A method of controlling seepage is mainly used in such cases — repeated grouting at low elevations of the UPL, including with the use of plastic grouts, which in individual cases accelerate setting of the additives.As measures for improving the seepage conditions and quality of monitoring, we can recommend plugging places of water shows through the grouting holes at an elevation of the UPL of 500–510 m, intensifying drainage in stretches of increased inflows and passages of the head beyond the drainage line, and broadening of geophysical and hydrogeological investigations for a detailed study of the character of change in permeability and seepage during fluctuations of the reservoir, especially at high elevations. During operation of the dam it is necessary not to exceed the attained rates and level of filling the reservoir (elevation 540.25 m), since at levels close to the NPL, the seepage discharge increases intensely.The underground contour of the Sayano-Shushenskoe dam is of high quality and operates effectively and reliably under conditions of a varying stress-strain state of the foundation during fluctuations of the reservoir level.Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 1, pp. 17–24, January, 1992.     

Improving fishery-independent indices of abundance for a migratory walleye population

The primary goal of many biological surveys is to provide an unbiased representation of trends of population abundance. However, there are often factors other than abundance that vary over time and influence catch rates and thus inferences about population trends from surveys. This is particularly true for highly mobile species because of interannual variation in the timing, extent, and duration of movements, and for surveys that are not randomized with respect to space and time. We developed general and generalized linear mixed models to standardize Canadian and United States fishery-independent surveys that provide an index of basin-level walleye (Sander vitreus) population abundance trends in Lake Erie (1983–2008). In Canadian waters, the probability of a non-zero catch was associated with the type of gill net set (canned > bottom sets), the presence of hypoxia (negative trend; −), and secchi depth (−). Positive catch rates were associated with the set type (canned > bottom) and water depth (+). In United States waters, survey catch rates were associated with secchi depth (−) and surface water temperature (+). For each case, the best model included random effects (interactions between year, week, basin, sub-basin) which accounted for a modest amount of the total variation. General abundance trends were similar between the standardized and nominal indices, but substantial annual variation in the direction and magnitude of the difference between indices was observed. We recommend the use of standardized indices for walleye population assessments because these account for factors influencing catch rates other than changes in abundance.     

Changes in Environmental Conditions During Dreissena Colonization of a Monitoring Station in Eastern Lake Erie

Effects of colonization and subsequent population density increases of Dreissena have been monitored annually at a site in eastern Lake Erie near the Niagara River. Striking changes in environmental conditions coincided with build-up of the Dreissena population from 1989 to 1992. A peak mean population density of 320,000 individuals/m² was observed in July 1991. Changes in conditions between 1988 and 1992 were characterized by: a progressive shift in sediment particle size distribution from fine sand of a mean particle size of 125–200 μm to silt-sized particles of a mean particle size of 4–7 μm; increased sediment concentrations of total organic carbon, polycyclic aromatic hydrocarbons (PAH) and some metals; secchi disc transparency increases from less than 4 m to over 6 m, chlorophyll a concentration decreases from over 3 μg/L to less than 1 μg/L and; decreases in numbers of native bivalves and polychaetes while gammarid amphipods and tubificid worms remained abundant. Data suggest that the large Dreissena population has altered depositional patterns of sediment in this area of eastern Lake Erie.     

综合水质标识指数法及单因子水质标识指数法在2013年官厅水库水质评价中的应用

综合水质标识指数评价法和单因子水质标识指数评价法是目前运用比较多的水质评价方法,尤其两种方法结合起来能完整地表达水体的综合水质信息,计算过程简单,既可进行定性评价,也可进行定量评价。本文应用综合水质标识指数法和单因子水质标识指数法选取代表性监测项目对北京市的重要水源地——官厅水库2013年的水质监测数据进行分析,评估官厅水库水体现状,为改善水质及生态环境提供科学依据,也为在北京市地表水源地水质评价中运用此类方法提供借鉴。     

A computationally efficient model for determining sound speed in shallow tropical freshwater systems,with field validation

The optimum performance of any underwater system depends on the propagation characteristics of the acoustic signals in the local water medium. Shallow tropical freshwater systems suffer from sub‐optimal performance of sonar systems deployed for any acoustic sensing because of random fluctuations of the water medium. The propagation characteristics depend largely on the sound speed variations defined by the site‐specific physical parameters such as water temperature, salinity and depth. The present study focuses on analysing the sound speed profile of a typical shallow freshwater system (Khadakwasla Lake; 18.43°N, 73.76°E), using regression models with the goal of deriving a computationally efficient model. To this end, a linear and polynomial regression model was developed, and their performance compared with the results of the model of Chen and Millero ( 1977 ), based on root mean square error (RMSE). In situ measurements of electrical conductivity, temperature and density (CTD) were carried out using a Valeport 602 CTD meter. Approximately 125 CTD samples were obtained during a 2‐day experimental study conducted at Khadakwasla Lake from 11 October 2017 to 12 October 2017. The data collection was undertaken throughout the day at multiple locations in the lake over a spatial distance of ~16 km. The Valeport 602 CTD meter uses the Chen and Millero ( 1977 ) formula, considered the most conventional sound speed equation. The computational complexity of the proposed models was measured in terms of the number of addition and multiplication operations required. The validation of both models was carried out by varying the model input parameters within defined limits. The model inputs have been derived from an in situ experimental data collection process in a typical shallow tropical freshwater system. The linear regression model exhibited an RMSE of 4.15 m/s, while the polynomial regression model exhibited a good agreement with an RMSE of 0.5 m/s.     

An Evaluation of Public Concerns About Water Management in the Palestinian Territory Pre,During, and Post the National Uprising

We have evaluated the extent of public concerns about water management in the Palestinian Territory (PT) through a survey of the main Palestinian newspaper over the last thirteen years divided in three periods: pre (1984–1987), during (1988–1991), and post national uprising period (1992–1996). The public concern in the PT about various water management aspects was clear and influenced by the prevailing political conditions indicating (1) poor concerns in the first and second period where full Israeli military control of the PT and harsh practices prevailed with relatively more emphasis on regional water issues and (2) extensive-strong concerns in the third period when the peace process started and a partial lift of some of the Israeli water practices took place, along with an increased freedom in expressing public concerns which was granted with more emphasis on local issues and problems. Lack and limitation of water available to Palestinians, alternative solutions, and water quality and pollution control constituted the overwhelming majority of the topics of concern to the public for the three periods studied. Palestinian concerns were always greater than regional ones for the three periods and all of the topics considered. Public concern in the PT about all other water management aspects was poor and negligible especially in the first two periods. A massive increase in public concern has been observed in the third period in which the public expressed their concern over most water management aspects, indicating a possible change in public attitude toward water and water management and reflecting the change of the political status by the start of the peace process and the signing of the peace agreements.