基于安全余量的污染物总量控制方法评述

借助污染物最大日负荷量（TMDL）的相关研究成果,阐述安全余量（MOS）的特征。结合安全余量的表现形式,阐述隐式、显式、FOEA计算安全余量的流程。对安全余量的定量化及其负荷分配研究是推动TMDL策略完善的关键。在梳理以往研究成果的基础上,从安全余量的产生机理出发,分析与污染物总量控制相关的安全余量计算过程。在考虑安全余量的前提下,依据水环境质量的控制目标,结合环境容量所允许的污染物排放量,论述了基于数学模型测算、可持续管理策略的污染物总量控制方法。以永定河流域污染物容量总量分配为例,进行基于安全余量的污染物分配应用研究,对有效减少污染物排放总量、实现水功能区水质达标具有重要意义。     

Application of medium class land cover maps to AVSWAT2000 for the prediction of inflow, CBOD, TN and TP for Yongdam Lake, Korea.

This study tests the efficacy of using medium class land cover maps vs. the large class maps produced by the Korean Ministry of Environment for prediction of flow and CBOD, TN and TP concentrations. AVSWAT2000 was chosen as a model to process information for a sample site, Yongdam Lake watershed area, Korea. The watershed was divided into 11 sub-watersheds, as was done for implementation of the Total Waste Load Management Act by the Korean government. Calibration of AVSWAT2000 was performed using a trial-and-error method, by comparing the root mean square errors of the observed data and calculated results. This study suggests that AVSWAT2000 can be successfully applied in estimating pollutant load considering hydrologic and site-specific conditions of watersheds. With further study, this approach may be applied to improve watershed-scale water quality management strategies, especially for TMDL developments.     

Microbial Pollution Characterization at a TMDL Site in Michigan: Effect of Hydrological Conditions on Pollution Loading

Communities throughout the United States are developing and implementing watershed management plans to address nonpoint sources of pollution and meet Total Maximum Daily Load (TMDL) requirements. Once a TMDL is established, a watershed management plan is developed and implemented to reduce contaminant sources and attain TMDL goals. Developing an effective TMDL and remediation plan should take into account fluctuation of pollution loadings and the timing of first-flush events. The objective of this study is to investigate the effect of hydrological conditions on microbial pollutant levels at a TMDL site during spring and summer storm events. A total of 64 water samples were collected from Sloan Creek in mid-Michigan in the spring/summer of 2015. All samples were analyzed to quantify concentrations of E. coli, bovine-associated Bacteroides (BoBac) gene markers, and human-associated Bacteroides (HuBac) gene markers. Discharge was the driving force of microbial contaminant loading in the studied water body. E. coli concentrations had significant strong correlation with precipitation and discharge, and BoBac concentrations were positively related to discharge. E. coli, BoBac and HuBac patterns suggested first-flush phenomena occurred during summer storms. E. coli permit exceedance rates increased from 31% before first-flush, to 100% during and after first-flush in the summer. The resulting information may help develop a plan for restoring impaired waters and establish the maximum amount of pollutants that the body of water can receive during different hydrological conditions.     

最大日负荷总量计划在非点源污染控制管理中的应用

概述了美国环保局提出的最大日负荷总量(TMDL)计划的背景、发展进程、组成框架,介绍了TMDL计划的主要内容、如何确定水质关键管理区,以及TMDL计划中评价污染源并估算污染负荷容量的方法。最后对我国非点源污染控制管理提出建议:分地区、分重点、分阶段地实施开发TMDL计划,注意开发简单、实用、经济的估算负荷量的模型与技术手段,在总量控制范围内,应保证TMDL计划与其他控制措施相结合,计划中应包括公众参与和评论等。     

The Green Bay saga: Environmental change,scientific investigation,and watershed management

The Green Bay watershed, draining a total area of approximately 40,468?km², comprises about a third of the Lake Michigan drainage. In the early years, fur trade was the dominant economic activity within the watershed. Later, when timber harvesting, papermaking, and agriculture came on the scene in the 19th and early 20th centuries, major environmental changes occurred in a relatively short period of time. Nutrient and sediment loadings, accompanied by organic wastes from sawmills and paper mills, resulted in a pollutant overload in the Fox River and in the eutrophication of the waters of lower Green Bay. Citizen complaints about these severely degraded conditions initiated a period of scientific investigation. Starting slowly with a few studies and surveys in the first half of the 20th century, serious investigatory work began at mid-century with support from the University of Wisconsin Sea Grant Institute. Examples of topics that have been investigated since then with support from numerous sources are: biological oxygen demand (BOD), phosphorus and total suspended solids loads, trophic status and food chain efficiencies, coastal wetland characterization, dynamics of the benthic layer, algae and abiotic solids, phosphorus cycling and mass balance, PCBs, seasonal hypoxia, and climate change impacts. These studies have provided the scientific foundation for government-led programs such as the Green Bay Remedial Action Program, the PCB clean-up program, and the TMDL program. Progress has been made—reduction in BOD is an example—but a fuller rehabilitation of this large-scale ecosystem remains an elusive goal. The saga goes on.     

An Integrated Approach for Targeting Critical Source Areas to Control Nonpoint Source Pollution in Watersheds

This study presents an integrated approach for targeting critical source areas (CSAs) to control nonpoint source pollution in watersheds. CSAs are the intersections between hydrologically sensitive areas (HSAs) and high pollution producing areas of watersheds. HSAs are the areas with high hydrological sensitivity and potential for generating runoff. They were based on a soil topographic index in consistence of a saturation excess runoff process. High pollution producing areas are the areas that have a high potential for generating pollutants. Such areas were based on simulated pollution loads to streams by the Soil and Water Assessment Tool. The integrated approach is applied to the Neshanic River watershed, a suburban watershed with mixed land uses in New Jersey in the U.S. Results show that several land uses result in water pollution: agricultural land causes sediment, nitrogen and phosphorus pollution; wetlands cause sediment and phosphorus pollution; and urban lands cause nitrogen and phosphorus pollution. The primary CSAs are agricultural lands for all three pollutants, urban lands for nitrogen and phosphorus, and wetlands for sediment and phosphorus. Some pollution producing areas were not classified into CSAs because they are not located in HSAs and the pollutants generated in those areas are less likely to be transported by runoff into streams. The integrated approach identifies CSAs at a very fine scale, which is useful for targeting the implementation of best management practices for water quality improvement, and can be applied broadly in different watersheds to improve the economic efficiency of controlling nonpoint source pollution.     

Mitigating lake eutrophication through stakeholder-driven hydrologic modeling of agricultural conservation practices: A case study of Lake Macatawa,Michigan

Lake Macatawa is a hypereutrophic water body that connects with Lake Michigan via a navigation channel. Excess phosphorus (P) concentrations have resulted in a Total Maximum Daily Load (TMDL) for total phosphorus (TP) in the lake, which has not been met. To guide land management and water pollution control in the Macatawa watershed, a Soil and Water Assessment Tool (SWAT) model and scenarios of agricultural best management practices (BMPs) were developed in consultation with stakeholders. Modelling emphasized incorporating practices representative of local agricultural conditions. Approaches to initializing high legacy soil P levels in SWAT were tested. The validated model was used to evaluate the influence of BMPs on lake water quality and identify which practices are necessary for meeting the TMDL. The model showed that eliminating manure applications would have small effect on curbing TP loading, but continuous no-till and high residue combined with already used subsurface manure application would yield notable TP reductions. Achieving TMDL-mandated TP reduction of 72% is possible through a widespread adoption of multiple BMPs (continuous no-till with high residue, cover crops, filter strips, and conversion of some marginal croplands to perennial grasses) across all the watershed’s row croplands. The study highlights how guidance from a local community interested in watershed improvement was integrated with modeling towards addressing eutrophication with informed watershed management. The Lake Macatawa case study presents a tractable system from which management solutions could be transferred to similar small agricultural tile-drained watersheds with high legacy soil P levels in the Great Lakes basin.     

Evaluation of Non-point Source Loads in the Reservoir Watershed using the GIS/GPS/RS Information Technologies and Numerical Models

Abstract

One of the recent concerns of reservoir eutrophication issues focuses on a fast assessment of the non-point sources pollution impact. It frequently requires an initial evaluation of the land use pattern and the reservoir assimilative capacity. This information is useful for estimating the non-point source loads, assessing the proper uses of natural resources in the watershed, and generating the essential control strategies when required. To achieve this goal, the state-of-the-art 3S information technologies, which properly integrates the skills of geographic information system (GIS), global positioning system (GPS) and remote sensing (RS), is viewed as an integrated means for reservoir land use assessment and watershed management. Substantial efforts in this study are placed upon identifying seven types of land use patterns in the watershed of the Tseng-Wen Reservoir in Southern Taiwan, which would directly assist in the required estimation of non-point sources pollution impact. With the aid of SPOT satellite images, Erdas Imagine⁰ image processing system, and ArcView⁰ GIS, the numerical model based on the export coefficient method yields an estimation of non-point source loads on a yearly basis with respect to four target constituents. These constituents of interest consist of total phosphorus (TP), total nitrogen (TN), biochemical oxygen demand (BOD), and total suspended solid (TSS). The analysis of assimilative capacity of the Tseng-Wen Reservoir based on various types of numerical models is also included for the evaluation of the eutrophication issue. Advanced management strategies with regard to the proper use of assimilative capacity of the Tseng-Wen Reservoir and the land resources in the watershed are then discussed in terms of three classified impact levels of non-point sources in the watershed. The methodology is proved practical, promising, and effective for assessing the eutrophication issue in the reservoir watershed within a short period of time     

Spatially Explicit Modeling of Land Use Specific Phosphorus Transport Pathways to Improve TMDL Load Estimates and Implementation Planning

Diffuse pollution from urban stormwater and agricultural runoff are among the leading causes of water pollution in the USA. A process-oriented, stakeholder-driven research approach was implemented in the small heterogeneous watershed of St. Albans Bay, Vermont to model the relative load of phosphorus from all sources, including diffuse transport pathways, and compared to goals and assumptions outlined by a Total Maximum Daily Load (TMDL) developed for phosphorus in Lake Champlain. Mass-balance and dynamic landscape simulation models were used to describe the distribution of the average annual phosphorus load to streams (10.57 t/year) in terms of space, time, and transport process. The majority of the phosphorus load comes from two subwatersheds dominated by clay soils, Stevens and Jewett Brooks. Dissolved phosphorus in surface runoff from the agricultural landscape, driven by high soil phosphorus concentrations, accounts for 41% of the total load to watershed streams. Direct discharge from farmsteads and stormwater loads, primarily from road sand wash-off, are also significant sources. Results reported in this study could help target watershed interventions both in terms of the types and locations of recommended best management practices (BMPs). The study offers an approach to attaining TMDL diffuse pollution targets in a cost-effective and participatory manner and could be replicated for other TMDL processes around the country.     

＂3S＂技术在密云水库及其上游流域水管理中的应用

密云水库现为中国华北地区库容最大的水库,主要担负着北京市及下游城市防汛与供水任务。探讨将"3S"技术应用于密云水库及其上游流域的水管理各项工作中,诸如水资源管理、防汛减灾、水污染突发事件处置以及水利工程监测等,有效提高相关工作的管理水平和效率,对水库及上游流域的管理工作给予越来越多的支持。     

Dynamics of wet‐season turbidity in relation to precipitation,discharge, and land cover in three urbanizing watersheds,Oregon

Frequent intense precipitation events can mobilize and carry sediment and pollutants into rivers, degrading water quality. However, how seasonal rainfall and land cover affect the complex relationship between discharge and turbidity in urban watersheds is still under investigation. Using hourly discharge, rainfall, and turbidity data collected from six stations in three adjacent watersheds between 2008 and 2017, we examined the temporal variability of the discharge–turbidity relationship along an urban–rural gradient. We quantified hysteresis between normalized discharge and turbidity by a hysteresis index and classified hysteresis loops during 377 storm events in early, mid, and late wet season. Hysteresis loop index and direction varied by site land cover type and season. Turbidity values peaked quicker in the watersheds with higher degrees of urban development than in a less urbanized watershed. The positive relation between discharge and turbidity was highest in two downstream stations in the mid wet season, whereas it was highest in two upstream stations in the early wet season. Correlation and regression analysis showed that maximum turbidity was best explained by discharge range, and the sensitivity of turbidity to discharge change was higher in the larger downstream watershed than in the small upstream watersheds. A flashiness index was negatively associated with the slope of turbidity versus discharge, suggesting that turbidity is difficult to predict solely on the basis of discharge in flashy urban streams. This paper contributes to a deeper understanding of the spatial and temporal variation of discharge–concentration relationship in urbanizing watersheds, which can help water managers increase the resiliency of water‐related ecosystem services to impacts of climate change.     

Determination of first flush criteria using dynamic EMCs (event mean concentrations) on highway stormwater runoff.

Recently the Ministry of Environment in Korea has developed the total maximum daily load program in accordance with the target pollutant and its concentration goal on four major large rivers. Since the program is largely related to regional development, nonpoint source control is both important and topical. Of the various nonpoint sources, highways are stormwater intensive land uses since they are impervious and have high pollutant mass emissions from vehicular activity. The event mean concentration (EMC) is useful in estimating the loadings to receiving water bodies. However, the EMC does not provide information on the time varying changes in pollutant concentration or mass emissions, which are often important for best management practice development, or understanding shock loads. Therefore, in this study a new concept, the dynamic EMC determination method, will be introduced to clearly verify the relationship between EMC and the first flush effect. Three monitoring sites in Daejeon metropolitan city areas were equipped with an automatic rainfall gauge and a flow meter for accumulating the data such as rainfall and runoff flow. The dynamic EMC method was applied to more than 17 events, and the improved first flush criteria were determined on the ranges of storm duration and accumulated rainfall.     

Threshold storm approach for locating phosphorus problem areas: An application in three agricultural watersheds in the Canadian Lake Erie basin

Hot-spots and hot-moments of phosphorus loads in an agricultural watershed depend not only on the watershed characteristics but also on the type and intensity of storms. Not all storms will generate phosphorus that can be considered problematic. A threshold storm is thus proposed and defined as the maximum storm intensity in which the phosphorus generated in a watershed is below seasonal phosphorus tolerance limit. To evaluate the threshold storm approach, separate Agricultural Non-point Source (AGNPS) models for three diverse small agricultural watersheds in southern Ontario, Canada were calibrated for runoff volume, sediment yield, and total phosphorus and run for representative storms with increasing return periods (2-year through 100-year). Results showed that in an upland watershed (Holtby), a 4.8-year early spring storm tend to generate phosphorus load above the threshold limit for the season. The same for low-land watersheds (Wigle and Jeannette) were, respectively, 14.9-year and 12.4-year. In all three watersheds, summer storms up to 100-year will fail to reach the seasonal tolerance limit for phosphorus. The critical source areas, identified based on the threshold storms, were distributed uniformly across the watersheds. As a phosphorus problem is essentially a source problem, such a simple yet robust approach to identify critical source areas of phosphorus can be useful in designing cost-effective best management practices.     

Microbial pollution characterization at a TMDL site in Michigan: Source identification

Communities throughout the Great Lakes basin are developing and implementing watershed management plans to address non-point sources of pollution and meet Total Maximum Daily Load (TMDL) requirements. Investigating sources of microbial contamination in key streams and creeks is critical for the development of effective watershed management plans. This work aims to present an approach that will facilitate source identification. In addition to conventional indicator analysis, the approach includes molecular analysis of species-specific markers and microbial community diversity analysis. We characterized microbial pollution in the Sloan Creek subwatershed in Ingham County MI, an impaired area, located in the Great Lakes Basin. To identify pollution sources (human or animal) and major sites of origin (tributaries with highest pollution loads) water samples were collected from three locations in the subwatershed representing the main creek upstream, main creek downstream, and tributary. A fecal indicator (E. coli) and host-specific human and bovine-associated Bacteroides genetic markers were quantified in all water samples. Results indicated that 54% of the samples from the three locations exceeded the recreational E.coli water quality guidelines. High concentrations of both human and bovine associated-Bacteroides indicated influence of multiple sources of fecal contamination. Statistical tests showed significantly different water characteristics between two of the sampling locations. Whole genome shotgun sequencing indicated fecal and sewer signatures, wastewater metagenome, human gut metagenome, and rumen gut metagenome in the water samples. Results suggested that probable sources of contamination were leakage from septic systems and runoff from agriculture activities nearby to Sloan Creek.     

Spatial Decision Support System for Watershed Management

A prototype spatial decision support system (SDSS) is presented for watershed management. The SDSS integrates landuse/landcover derived from the remote sensing data, real-time hydrological data, geographic information system, and a model-based subsystem for computing soil loss, land capability classification and engineering measures. A graphical user interface has been developed to allow effective use by decision makers. The model-based subsystem employs a process-based soil erosion model to compute soil loss in spatial environment. Computed pixel-based soil loss information is an input to the land capability classification and watershed management modules. The developed SDSS can help the end users in avoiding the laborious procedures of soil erosion calculations and analysing various thematic layers to get suitable watershed management practices. The SDSS for watershed management is applied to the Tones watershed in India to compute soil loss, to prioritise watersheds, and to suggest various watershed management practices.     

Development of a new indicator of pollutant loads and its application to the Chesapeake Bay watershed

Pollutant load reductions are often required to restore aquatic ecosystems experiencing eutrophication. Loads can be estimated using watershed models or data from monitoring stations, however data availability can limit the timeliness or comprehensiveness of the load estimates. We developed an approach to address this challenge that used watershed model results to estimate the proportion of annual nonpoint source nitrogen (N), phosphorus (P) and sediment (Sed) loads derived from unmonitored catchments. This proportion was multiplied by the nonpoint portion of United States Geological Survey (USGS) estimated annual river loads to account for annual variation in hydrologic conditions. Total loads were calculated as the sum of measured river loads, reported point sources from unmonitored areas and the estimated nonpoint source loads from unmonitored catchments. We applied this approach to the Chesapeake Bay because of its socio‐economic and ecological importance. Median watershed loads for N, P and Sed were 140, 6.4 and 3030 Mg year^?1, respectively (1990–2004). Nonpoint source loads from the monitored areas constituted the greatest source of N, P and Sed (55, 47 and 74% respectively) to the Bay. The high N, P and Sed yield rates (7.3, 0.38 and 99 kg ha^?1 year^?1, respectively) from nonpoint loads originating from unmonitored areas near the Bay resulted in 25, 32 and 26% (N, P and Sed, respectively) of the Bay's total loads (excluding direct atmospheric deposition, shoreline erosion and oceanic inputs). Disproportionately high loads of P and Seds were associated with years that experienced elevated discharge whereas N loads were directly related to discharge. Error estimates indicated that our methods were most reliable for N (±6%) but reasonable for P (±22%) and provide an effective technique for the timely estimation of pollutant loads from watersheds with unmonitored catchments. Management strategies that decrease N deposition and reduce runoff to control P and Sed transport will effectively reduce pollutant loads. Published in 2010 by John Wiley & Sons, Ltd.     

Framework for Assessment of Relative Pollutant Loads in Streams with Limited Data

Abstract

A framework that integrates two data-driven techniques is proposed and developed to assess fecal coliform loadings in natural streams. A relationship between transport medium (streamflow) and non-conservative pollutant (fecal coliform) load is first developed using conventional regression technique. The spatial distribution of the fecal load over watersheds is then captured using artificial neural networks through a disaggregation scheme. Streamflow, as a surrogate for non-conservative fecal load, has been used in the disaggregation process. The framework is applied to an area that encompasses four USGS 8-digit Hydrologic Unit Code (HUC) watersheds in the southeastern region of Kentucky, USA. The study attempts to address two major issues: (i) assessment of relative pollutant loads from watersheds and (ii) evaluation into possible reduction in the number of monitoring stations to meet the budgetary constraints. Preliminary results indicate the potential of this approach in assessing the relative fecal loading contribution from different watersheds with the help of conservative hydrological parameters, especially in data-poor conditions.     

Surface Loading from Pollutants in Precipitation in Southern Ontario: Some Climatic and Statistical Aspects

Monthly samples of precipitation during the period June 1975 to June 1977 from bulk type precipitation gauges located in six watersheds in southern Ontario were analyzed for sulphate, nitrogen, phosphate, chloride, calcium, sodium, potassium, magnesium, heavy metals, and PCBs. The relationship between the surface loading of the pollutant and the amount of precipitation during the observation period was investigated and a significant relationship at the .05 level was found for all pollutants except sodium. The loadings in g/ha/d were tested statistically for spatial and temporal variability. All parameter loadings showed a downward trend over time and it was suggested that this is due to decreased precipitation during the second year of observation. No significant seasonal differences were found in the surface loadings. Analysis of variance tests indicated that at the .05 level of significance, no significant differences in monthly loadings were observed for all parameters except calcium and magnesium, although some locations were very near and others hundreds of kilometers distant from the major sources of industrial pollutants.     

Evaluation of BASINS/WinHSPF applicability for pollutant loading estimation for a Korean watershed.

Applicability of a widely accepted watershed-based water quality assessment tool (BASINS) and its associated watershed model (WinHSPF) was evaluated on the Seamangeum watershed in Korea. The study site is the largest polder project area in Korea and its environmental quality has been debated for the last five years. BASINS was found to be a convenient and powerful tool for assessment of watershed characteristics, and provided various tools to delineate the watershed into land segments and river reaches, reclassify land use, and parameterize for WinHSPF simulation. Calibration results were satisfactory showing model efficiency over 0.80 for stream flow, temperature, and dissolved oxygen simulation, and model output for water quality constituents also reasonably matched the observed data. It was demonstrated that calibration with dry-day data for a relatively long period might be adequate to simulate hydrologic characteristics and water quality of the watershed with WinHSPF, and using parameters generated with BASINS for nonpoint source pollution simulation is suggested when enough wet-day monitoring data are not available. The unit-area load of biochemical oxygen demand, total nitrogen, and total phosphorus was 27.8, 48.2, and 4.3 kg/ha/yr, respectively. These values are within the expected range but on the high side of the reported values, which implies that effective control measures are required to protect water quality of the downstream reservoir. Overall, BASINS/WinHSPF was applicable and found to be a powerful tool in pollutant loading estimation from the watershed, and its use in Korea is recommended.     

上海海域污染源分析及控制对策

为了研究陆源污染对上海海域的影响,分析长江入海污染物通量的季节变化、黄浦江与长江对上海海域污染的贡献率、上海海域主要污染物的时空分布特征。结果表明:污染物随季节基本呈规律性变化,长江入海污染物对海域污染的贡献远大于黄浦江,长江和黄浦江对上海海域影响最大的污染物是TP;上海市主要污水排放系统对上海海域的N、P污染有很大贡献。最后提出控制上海海域污染形势的对策建议。