MATCHING NATURAL WATER COLORS TO MUNSELL STANDARDS1

ABSTRACT: Color of natural waters strongly influences their aesthetic appeal, suitability for recreational use, and aquatic habitat, but methods for routine specification of color have been lacking. An improved method has been developed for specifying water colors in the field. The water color, seen through an underwater viewer, is matched directly to Munsell standard patches observed simultaneously. The Munsell color-matching method was verified versus measurements of the underwater light field, made with a submersible spectroradiometer in 20 different natural waters in New Zealand (mainly lakes), which varied widely in color and other optical characteristics. Hue, the most important color attribute of natural waters, could be matched accurately; the saturation and brightness less so. Color standard patches are not available covering the full range of typically dark water colors, but fortunately, brightness can be measured with simple submersible light sensors. The Munsell color matching method seems suitable for routine water resources survey and monitoring.     

LAKE WATER QUALITY ASSESSMENT FROM LANDSAT THEMATIC MAPPER DATA USING NEURAL NETWORK: AN APPROACH TO OPTIMAL BAND COMBINATION SELECTION1

Abstract: The concern about water quality in inland water bodies such as lakes and reservoirs has been increasing. Owing to the complexity associated with field collection of water quality samples and subsequent laboratory analyses, scientists and researchers have employed remote sensing techniques for water quality information retrieval. Due to the limitations of linear regression methods, many researchers have employed the artificial neural network (ANN) technique to decorrelate satellite data in order to assess water quality. In this paper, we propose a method that establishes the output sensitivity toward changes in the individual input reflectance channels while modeling water quality from remote sensing data collected by Landsat thematic mapper (TM). From the sensitivity, a hypothesis about the importance of each band can be made and used as a guideline to select appropriate input variables (band combination) for ANN models based on the principle of parsimony for water quality retrieval. The approach is illustrated through a case study of Beaver Reservoir in Arkansas, USA. The results of the case study are highly promising and validate the input selection procedure outlined in this paper. The results indicate that this approach could significantly reduce the effort and computational time required to develop an ANN water quality model.     

Assessing Risk in Operational Decisions Using Great Lakes Probabilistic Water Level Forecasts

/ A method adapted from the National Weather Service's Extended Streamflow Prediction technique is applied retrospectively to three Great Lakes case studies to show how risk assessment using probabilistic monthly water level forecasts could have contributed to the decision-mak-ing process. The first case study examines the 1985 International Joint Commission (IJC) decision to store water in Lake Superior to reduce high levels on the downstream lakes. Probabilistic forecasts are generated for Lake Superior and Lakes Michigan-Huron and used with riparian inundation value functions to assess the relative impacts of the IJC's decision on riparian interests for both lakes. The second case study evaluates the risk of flooding at Milwaukee, Wisconsin, and the need to implement flood-control projects if Lake Michigan levels were to continue to rise above the October 1986 record. The third case study quantifies the risks of impaired municipal water works operation during the 1964-1965 period of extreme low water levels on Lakes Huron, St. Clair, Erie, and Ontario. Further refinements and other potential applications of the probabilistic forecast technique are discussed.KEY WORDS: Great Lakes; Water levels; Forecasting; Risk; Decision making     

PLANNING FOR THE REHABILITATION OF GRAVEL PITS1

ABSTRACT: By field investigations and planning, it is profitable to rehabilitate gravel pits as recreational lakes in urban areas. Some of the important aspects to be considered are topography, soil, surface water and groundwater. A case study is presented and some general guidelines in the rehabilitation process are given. This kind of a use for derelict land is important at the present time as there is a growing demand for recreational lakes in urban areas.     

Can Red Pay for Blue? Methods to Estimate the Added Value of Water in Residential Environments

As a result of climate changes, more land is now needed in the Netherlands for water retention in towns and the countryside. Recently, this perceived need has resulted in new forms of water management and spatial planning strategies. Multi-functional land use is an option such as housing in combination with retention lakes. Some argue that the market potential is high and that water has an added value in residential environments. This added value could be used to compensate for non-profitable investments such as the creation of lakes. The key question is how to value this amenity. It is argued that non-economists often assume that a valuation is just a technique. The authors challenge this by presenting an overview of economic perspectives as well as techniques. A literature review reveals the main valuation perspectives and suggests estimated added values of 10‐15% for the seashore, 5‐10% for river locations (streams), and 5% for lakes.     

THE DILUTION/FLUSHING TECHNIQUE IN LAKE RESTORATION1

ABSTRACT: Dilution/flushing has been documented as an effective restoration technique to restore eutrophic Moses and Green Lakes in Washington State. The dilution water added to both lakes was low in nitrogen and phosphorus content relative to the lake or normal input water. Consequently, lake nutrient content dropped predictably. Dilution or flushing rates were about ten times normal during the spring-summer periods in Moses Lake and three times normal on an annual basis in Green Lake. Improvement in quality (nutrients, algae, and transparency) was on the order of 50 percent in Moses Lake and even greater in Green Lake. The facilities for supplying dilution water were largely in place for the cited lakes; thus, costs for water transport were minimal. Available facilities, and therefore, costs, for water transport would usually vary greatly, however. Achieving maximum benefit from the technique may be more limited by availability of low nutrient water rather than facilities costs. Quality improvement may occur from physical effects of algal cell washout and water column instability if only high nutrient water is available.     

TROPHIC STATE EVALUATION FOR SELECTED LAKES IN GRAND TETON NATIONAL PARK1

ABSTRACT: Increased visitation at Grand Teton National Park (GTNP) has raised concerns about impacts on surface water in the park. The purposes of this study are to perform a benchmark trophic state survey for comparison to future evaluations and to identify possible areas of concern. Four watershed regions based on geographic and geologic features were delineated for study. Six Alpine lakes, six Moraine lakes, three Valley lakes, and two Colter Bay lakes are evaluated. Lakes were sampled for total phosphorus (TP), chlorophyll‐a, and transparency. The water quality, as defined by trophic state, in the park is generally good. Oligotrophic to mesotrophic conditions were found in the Alpine and Moraine lakes and mesotrophic to eutrophic conditions were found in the Colter Bay and Valley lakes. High inflow TP concentrations in the park's northeast side may be due to the presence of natural geologic phosphate from the Phosphoria Formation.     

Lake Water Levels and Associated Hydrologic Characteristics in the Conterminous U.S.

Establishing baseline hydrologic characteristics for lakes in the United States (U.S.) is critical to evaluate changes to lake hydrology. We used the U.S. Environmental Protection Agency National Lakes Assessment 2007 and 2012 surveys to assess hydrologic characteristics of a population of ~45,000 lakes in the conterminous U.S. based on probability samples of ~1,000 lakes/yr distributed across nine ecoregions. Lake hydrologic study variables include water‐level drawdown (i.e., vertical decline and horizontal littoral exposure) and two water stable isotope‐derived parameters: evaporation‐to‐inflow (E:I) and water residence time. We present (1) national and regional distributions of the study variables for both natural and man‐made lakes and (2) differences in these characteristics between 2007 and 2012. In 2007, 59% of the population of U.S. lakes had Greater than normal or Excessive drawdown relative to water levels in ecoregional reference lakes with minimal human disturbances; whereas in 2012, only 20% of lakes were significantly drawn down beyond normal ranges. Water isotope‐derived variables did not differ significantly between survey years in contrast to drawdown. Median E:I was 20% indicating that flow‐through processes dominated lake water regimes. For 75% of U.S. lakes, water residence time was less than one year and was longer in natural vs. man‐made lakes. Our study provides baseline ranges to assess local and regional lake hydrologic status and inform management decisions in changing environmental conditions.     

A Tool for Modeling the Winter Oxygen Depletion Rate in Arctic Lakes1

Abstract: Many arctic lakes freeze completely in winter. The few that retain unfrozen water for the entire winter period serve as overwintering fish habitat. In addition to serving as fish habitat, water in arctic lakes is needed for industrial and domestic use. Permits for water extraction seek to maximize water use without impacting dissolved oxygen (DO) levels and endangering fish habitat. The relationship between lake volume, winter DO budget, and extraction of water through pumping has historically not been well understood. A management model that could estimate end‐of‐winter DO would improve our understanding of the potential impacts of different management strategies. Using under‐ice DO measurements (November to April) taken from two natural lakes and one flooded gravel mine on the North Slope of Alaska, a physically based model was developed to predict end‐of‐winter DO concentration, water‐column DO profiles, and winter oxygen depletion rate in arctic lakes during periods of ice cover. Comparisons between the measured and model‐predicted oxygen profiles in the three study lakes suggest that the depth‐based DO modeling tool presented herein can be used to adequately predict the amount of DO available in arctic lakes throughout winter.     

西南地区高尔夫球场人工湖水体富营养化状况及其季节变化——以成都麓山高尔夫球场人工湖为例

为评价西南地区高尔夫球场人工湖的营养状态,并探讨影响球场湖泊富营养化的原因,2010年1月至12月,以成都麓山高尔夫球场为例,对球场的4个球道人工湖(12号球道、13号球道、14号球道和16号球道)水体的水体理化性质进行监测。结果显示:人工湖的富营养化程度呈季节性变化,其在试验期内综合营养状态已达到轻度富营养的状态。水体营养盐主要来自于球场草坪的施肥,氮、磷等营养物质随降水输入人工湖,从而引起的湖泊富营养化,尤其体现在多雨的夏季。     

Use of Synthetic Aperture Radar for Selecting Alaskan Lakes for Winter Water Use1

Abstract: Water resources are limited in many areas of the North Slope, Alaska, particularly during winter. Water is used by the oil industry for ice road construction and maintenance, drilling and facility operations, and potable water supplies. The coastal plain between Teshekpuk Lake, in the National Petroleum Reserve‐Alaska (NPR‐A) and the Colville River has numerous shallow lakes, but further south in the northern foothills of the Brooks Range, and east to the Canning River, lakes are fewer. While many oil and gas lease sales have been conducted, or are proposed, access to the leases may be limited because of the lack of available water for ice road construction. Ice roads are the main means by which exploration is conducted in the Arctic, putting a stress on freshwater bodies that do not freeze to the lakebed in winter. Lakes that do not freeze to the lakebed also serve as overwintering habitat for fish. The purpose of this paper is to report on the potential distribution of water bodies that may provide overwinter water in selected areas from Teshekpuk Lake to the Canning River. The project used synthetic aperture radar (SAR) imagery to search for the presence of water in lakes in March 2006. In the Kuparuk and Canning SAR images, 52 and 61% of lakes were frozen to their beds by March 2006, accounting for 49 and 57% of the lake area in these study regions. Conversely, only 2% of the lakes in the Teshekpuk region were frozen to the bottom by March 2006. Unfrozen water was more available because of deeper and more numerous lakes in the Teshekpuk Lake region (west) than in the Canning River area (east). While only specific SAR tiles were analyzed herein, the method will be a useful tool for land managers who seek to evaluate the potential for ice road construction across the Arctic.     

Bottomfast Ice Mapping and the Measurement of Ice Thickness on Tundra Lakes Using C‐Band Synthetic Aperture Radar Remote Sensing1

Abstract: Industrial activity in Canada’s north is increasing, placing demands on the use of water from lakes to build ice roads. Winter water withdrawal from these lakes has the potential to impact overwintering fish. Removal of water from small lakes can decrease oxygen and habitat available to fish. To address this issue, a protocol has been developed by the Department of Fisheries and Oceans outlining water withdrawal thresholds. Bathymetric surveys are the traditional method to determine lake depth, but are costly given the remoteness of northern lakes. This paper investigates the use of satellite C‐band synthetic aperture radar (SAR) remote sensing technology as a potential alternative or complement to traditional survey methods. Previous research has shown that a SAR can detect the transition from grounded to floating ice on lakes, or if a lake is completely frozen. Grounded ice has a dark signature while floating ice appears very bright in contrast. Similar results were observed for the datasets acquired in the study area. This suggests that lakes that freeze completely to the bottom can be identified using SAR. Such water bodies would not be viable fish overwintering habitat and can therefore be used as water sources without thresholds necessary. However, attempts to accurately calculate the depth of the ice at the grounded‐floating ice boundary using bathymetric profiles acquired in the summer and lake ice thickness measurements from a reference lake near Inuvik proved to be unreliable.     

Effects of Water Withdrawal From Ice‐Covered Lakes on Oxygen,Temperature, and Fish1

Abstract: In northern regions, large volumes of water are needed for activities such as winter road construction. Such withdrawals, particularly from small lakes, can reduce oxygen concentrations and water levels, potentially affecting aquatic organisms. Withdrawal limits have been developed by regulatory agencies, but are largely theoretical. Water withdrawal thresholds were tested in two small lakes by removing 10% and 20% of their respective under‐ice volumes and comparing oxygen parameters, temperature, over‐wintering habitat, and northern pike (Esox lucius) abundance to reference conditions. Because of a milder winter, oxygen parameters were elevated in reference lakes in the period following withdrawal compared to the prewithdrawal period. The 10% withdrawal resulted in a ?0.2 m shift in the oxygen concentration profile at 4 mg/l in that lake, but had no effect on total volume‐weighted oxygen, or volume of over‐wintering habitat. In contrast, the 20% withdrawal caused 0.7 m reduction in the oxygen concentration profile at 4 mg/l compared to the previous year, a 26% decline in the volume‐weighted oxygen concentration, and a 23% reduction in the volume of over‐wintering habitat compared to prewithdrawal conditions. Water temperatures were slightly (≤ 10%) colder in the upper strata in the year following the withdrawal in both withdrawal and reference lakes. Northern pike abundance was not impacted by water withdrawals in either of the lakes. The results of this study show that the effects of water withdrawal on the parameters investigated reflected the characteristics of the lakes, and would therefore be expected to vary from lake to lake. Policy development to mitigate impacts must therefore reflect the site‐specific nature of water withdrawal.     

Selenium Bioaccumulation in Stocked Fish as an Indicator of Fishery Potential in Pit Lakes on Reclaimed Coal Mines in Alberta, Canada

Pit lakes are a common reclamation strategy for open pit mines; however, there is a concern about their water quality and suitability as fish habitat because they are often contaminated by metals or metalloids. This study assessed the exposure of fish and invertebrates to selenium (Se) and other metals and metalloids in pit lakes formed by open pit coal mining in Tertiary (thermal coal) and in Cretaceous (metallurgical coal) bedrock. Juvenile hatchery rainbow trout, Oncorhynchus mykiss, and brook trout, Salvelinus fontinalis, were stocked into two thermal coal pit lakes (water Se < 2 μg/L, low water Se) and two metallurgical coal pit lakes (water Se > 15 μg/L, high water Se). Se accumulation in stocked fish and concentrations in invertebrates were characterized over a period of 2 years. In the metallurgical pits, invertebrates had higher Se concentrations and fish accumulated Se to higher levels (exceeding USEPA tissue Se guidelines) than biota in the thermal pits. Rainbow and brook trout accumulated similar concentrations of Se in their muscle and exhibited a similar relationship between whole-body and muscle Se concentrations. These results may be used by resource managers to assess compliance with whole-body tissue Se guidelines and to determine if pit lakes in coal mining areas pose a significant Se risk to wildlife or human health. The high Se exposure in metallurgical coal pits indicates that under the current mining and reclamation strategy, these lakes are not suitable for management as recreational “put and take” fisheries.     

应用于滇池草海生态修复工程的植物浮岛制备技术

本文介绍最新开发的一种不受自然条件严格限制的新型植物浮岛制作技术。该种植物浮岛主要应用于水位较深的湖泊、河口水域及城市最观水体生态修复工程。具有植物根系密实、抗风浪能力强、净水作用明显、景观效果好、维护管理方便等特点。本文对该技术方案、工程效果进行了介绍，并将本技术与同类技术特点进行对比分析和探讨。     

NEBRASKA'S SANDHILLS LAKES: A HYDROGEOLOGIC OVERVIEW1

ABSTRACT: Lakes, marshes and wet meadows occur in the broad, flat, interdune valleys of the Nebraska Sandhills, a vegetation-stabilized dune field underlain by sediments containing an enormous supply of groundwater. Hydrologic, geologic and possibly climatologic factors influence the chemical quality of lake water. Central and eastern lakes generally are in connection with the groundwater reservoir. The hydrologic nature of western lakes and the cause of their high alkalinity is not fully understood. Lakes in close proximity may vary in both their chemical characteristics and in the degree to which they change in size and depth over time. Climatic, hydrogeologic and natural lake-aging processes of accumulation of organics appear to be primarily responsible for lake-size variations.     

GROUNDWATER FLOW SYSTEM ANALYSIS IN LAKE ENVIRONMENTS,WITH MANAGEMENT AND PLANNING IMPLICATIONS1

ABSTRACT. Evaluation of lakes as they are related to groundwater flow systems is of special concern prior to efficient development and planning operations. Both naturally occurring and artificially created lakes are being developed rapidly as recreational and residential areas. Simultaneously, field verification of theoretical groundwater flow system behavior has progressed to the point where hydrogeologists trained to understand basic concepts of flow-system analysis can begin to broaden their research and service base, and to work closer with planners, developers, and engineers. It is suggested that particular efforts be directed toward a greater evaluation of physical, chemical, and biological aspects of potentially developable lake sites to aid in selecting use patterns in accord with these factors. Many lake developments are not in harmony with the physical environment. The resulting misuse of resources is often expressed as accelerated eutrophication of lakes, or by quality degradation of shallow groundwater flow systems contiguous to them. Lakes can no longer be considered as separate entities. Methodology for investigating the interchange of surface and near-surface water is adequate however, the application of known interchange relationships is inadequate. .     

Identification and mapping of submerged plants in a shallow lake using Quickbird satellite data

Turkey is a country rich in lakes and wetlands--monitoring of all these will require advances in technology such as remote sensing. In this study, the aquatic plants of the large and shallow Lake Mogan, located in Central Anatolia were identified and mapped using high spatial resolution Quickbird imagery. As Lake Mogan is an important bird area the assessment of submerged plant species is of great value for ecosystem conservation and management. Quickbird multispectral image acquired on August 6, 2005 was geometrically corrected and a water mask was used based on strong absorption of Near Infrared (NIR) wavelengths by calm, clear and deep water. The water mask was applied using band reflectance values for a specific pixel satisfying the conditions of band decreasing property (Green>Red>NIR) and NIR相似文献   

Regional Representativeness of Swedish Reference Lakes

/ Recent focus has been placed on ecoregion delineations for providing an appropriate framework for monitoring and assessment of region-specific attainable water/habitat quality. Using an ecoregion approach to stratify variance, this study was conducted to determine whether earlier (subjectively) selected Swedish reference lakes may be considered as regionally representative reference sites when compared with a randomly selected lake population. Predictive modeling by discriminant function analysis with lakes classified by ecoregion and lake surface area and six physicochemical variables showed that the greater majority of reference lakes may be considered as regionally representative. The highest proportion of lake "misclassifications" occurred in the boreonemoral ecoregion, a relatively diverse ecoregion of southern Sweden. This apparent bias may be in part be due to the criteria used in selecting regional reference lakes. In the earlier selection of reference lakes emphasis was placed on lakes not being adversely affected by land usage or pollutant discharges, consequently forest lakes were often overrepresented and sites in agricultural areas underrepresented in the selected reference sites. As a complement to predictive modeling, PCA ordination showed the placement of reference lakes within the random lake population and indicated where reference sites might be missing along potentially important ecological gradients. KEY WORDS: Regionalization; Ecoregion; Representativeness; Reference; Ordination; Modeling; Temperate lakes     

GEOMETRIC VARIATIONS IN RESERVOIR WATER QUALITY1

ABSTRACT: In developing water quality models for lakes and reservoirs, the assumptions of one-dimensionality (i.e., water quality changes are significant only in one dimension – usually depth), as well as two-dimensionality (considering the length and depth of the water body), have been utilized to predict water quality. In both caws, the assumption of lateral homogeneity is made. A field study was undertaken to determine the change of water quality in the lateral dimension. The main study reservoir was Center Hill Lake in Middle Tennessee. Data were also obtained for Cherokee Lake in East Tennessee. Several water quality parameters (temperature, dissolved oxygen, pH, conductivity, and oxidation reduction potential) were analyzed over the length, breadth, and depth of these reservoirs from pre-stratification through post-stratification. The statistical and theoretical three-dimensional analysis showed the expected variation for each water quality parameter in each direction. The influence of the lateral dimension on water quality management and modeling was found to be negligible.