Estimating Nutrient Outflow from Argicultural Watersheds to the River Kali in India

In India, fertilizers and chemicals are applied to different crops, which in turn, cause nonpoint source pollution of surface water and groundwater of the region. In the present work, extensive water quality surveys were done to estimate the nutrient outflow from three small agricultural watershed of the Kali Basin, Uttar Pradesh, India. A total of 576 field data sets have been collected during March 1999–February 2000 from four sampling stations. During the monsoon period the nutrient outflow from these agricultural watersheds were found to be orders of magnitude higher than during the nonmonsoon period. The percentage of nutrients outflow from each watershed was estimated on a monthly basis by obtaining periodical cropping patterns and the amounts of fertilizer applied for each watershed. A maximum of 85% of total nitrate and 70% of total orthophosphate applied in the field was found to be lost during the month of July from the third agricultural watershed having maximum slope and minimum watershed area. Using the data sets generated during field surveys, commonly used modeling approaches based on mass balance differential loading and decay fraction were tested for their applicability to estimate nonpoint source (NPS) pollution in the River Kali. The NPS concentration and load values computed from these approaches were compared with the NPS values measured in the field and the performances of different equations have been evaluated using error estimations such as standard error, normal mean error, mean multiplicative error, and correlation statistics. Further, a refined model based on reaction kinetics and mass balance differential loading has been proposed for the River Kali that minimizes error estimates and improves correlation between observed and computed nonpoint source loads.     

Dual Discharge Approach to Accessing Assimilative Capacity: Probabilistic Analysis and Management Application

A dual discharge strategy has been proposed for management of the effluent from the Syracuse Metropolitan Treatment Plant (Metro). The approach involves routing the discharge to the Seneca River when assimilative capacity is available there and to Onondaga Lake when it is not. Application of a deterministic modeling approach has demonstrated that the dual discharge strategy is effective in meeting water-quality standards/goals in both the river [dissolved oxygen (DO)] and the lake [total phosphorus (TP)] under summer average conditions of river flow and upstream boundary condition DO. Here, that analysis is extended to include a probabilistic treatment of the impact of natural variability in river flow and DO boundary conditions on the feasibility of this management option. Model simulations, incorporating these key sources of system variability, indicate that the dual discharge strategy will meet the lake management goal for TP ～ 94% of the time, with no attendant violation of river DO standards. Excursions from the lake TP goal, occurring ～ 6% of the time, range from 1–5?μg?L?1, are within the range of uncertainty in indicators applied in identifying trophic status. This novel management option is compared with an in-lake discharge alternative in terms of technical and economic feasibility and public acceptance of resultant water quality. Additional management actions, recommended to accompany implementation of the dual discharge strategy, are discussed.     

Parameter Sensitivity and Predictive Uncertainty in a New Water Quality Model, Q2

A new dynamic model of water quality, Q2, has recently been developed, capable of simulating large branched river systems. This paper describes the application of a generalized sensitivity analysis (GSA) to Q2 for single reaches of the River Thames in southern England. Focusing on the simulation of dissolved oxygen (DO) (since this may be regarded as a proxy for the overall health of a river); the GSA is used to identify key parameters controlling model behavior and provide a probabilistic procedure for model calibration. It is shown that, in the River Thames at least, it is more important to obtain high quality forcing functions than to obtain improved parameter estimates once approximate values have been estimated. Furthermore, there is a need to ensure reasonable simulation of a range of water quality determinands, since a focus only on DO increases predictive uncertainty in the DO simulations. The Q2 model has been applied here to the River Thames, but it has a broad utility for evaluating other systems in Europe and around the world.     

Jackson River Modeling: 50‐Year Perspective

The development of water quality models, and also the nature of water quality impairment, is uniquely presented in the point source dissolved oxygen (DO) modeling completed in the Jackson River (Virginia) over the past 50?years. Various water quality modeling studies have been completed in the Jackson River over the years starting with the earliest of modeling frameworks, the Streeter–Phelps equation (1950s and 1960s); progressing to a biochemical oxygen demand–DO model (1970s and 1990s) including diurnal photosynthetic effects (DIURNAL); a Monte Carlo DO analysis using the DIURNAL model (1990s); to the most recent modeling that is currently developing a periphyton model to assess the impact of nutrient loadings on the periphyton community and ultimately DO levels (2000). These early modeling studies were completed by such modeling forefathers as Clarence J. Velz and Donald J. O'Connor, both completing their work at academic institutions (Manhattan College and the University of Michigan) and private consulting firms (Hydroscience and HydroQual, Inc.). Interesting to note is that Earle B. Phelps taught Clarence J. Velz, Donald J. O’Connor’s eventual professor at Manhattan College. Other work completed on the river by early environmental engineers included reaeration studies by Ernest C. Tsivoglou (1966) and the first activated sludge wastewater treatment design for a pulp and paper mill by Wesley Eckenfelder (1950s). The studies investigated: how to improve existing DO conditions in the river; the effects of color reductions on diurnal DO swings; proposed upstream flow regulation effects on water quality and river temperature; and the impact of instream oxygen addition.     

Modeling Nonpoint Source Pollutant Losses from a Small Watershed Using HSPF Model

Hydrologic models play an important role in the assessment of nonpoint source (NPS) pollution, which is essential for the environmental management of water resources. The present study has been undertaken to evaluate the applicability of a physically based continuous time scale, hydrological, and water quality computer model—Hydrologic Simulation Program-Fortran (HSPF)—in simulating runoff and sediment associated NPS pollutant losses from a small mixed type (land under agriculture, shrubs and forest, rocks, grasses) watershed of the Damodar Valley Corporation, Hazaribagh, India. Water soluble NO3–N, NH4–N, and P were considered as pollutants and their concentrations in the runoff were measured at the outlet of the watershed, randomly for 15 dates during the monsoon season (June–October) of 2000 and 2001. The model calibration and validation results reveal that the seasonal trend of HSPF simulated runoff, sediment yield, and NPS pollutants compared reasonably with their measured counterparts. Although the concentrations of pollutants were generally overpredicted for NO3–N and underpredicted for NH4–N and water-soluble P in the month of June when fertilizers releasing NH4–N and P are applied in rice fields, the differences in the mean concentration were not significantly different at a 95% level of confidence. Variation in the simulated losses of water soluble N and P species between the years occurred largely due to differences in the amount and distribution of rainfall. These results indicate that the HSPF model can be used as a tool for simulating runoff and sediment associated NPS pollution losses from the study area.     

南京生态科技岛海绵城市河道系统植物技术设施对水体重金属及营养盐净化能力评价

为探究海绵城市植物技术设施对重金属及营养盐净化能力,以江心洲南京生态科技岛河道系统为研究对象,对其上下游水体中重金属及营养盐含量进行分析,通过综合污染指数法对上下游重金属风险进行评估,采用冗余分析及Spearman相关系数探究水体环境因素对重金属含量的影响,利用河道区域四种植物技术设施(河岸缓冲带、植被过滤带、生态浮岛、台地式石笼护岸)探究不同植物组合对水体中污染物的净化能力。结果显示,江心洲河道上游重金属的枯水期、丰水期及平水期WQI值分别为1.85、1.74及2.90,分别对应为重金属轻度污染、轻度污染及中度污染。而河道下游重金属的枯水期、丰水期及平水期的WQI值分别为0.18、0.30及0.52,均未存在污染现象。河道上游水体中pH是影响重金属含量的最重要因素,pH与溶解氧(DO)、总氮(TN)、五日化学需氧量(COD₅)及总磷(TP)呈正相关。河道下游水体的pH也是影响水中重金属含量最重要的环境因素,其与溶解氧(DO)呈显著正相关。水体中营养盐净化能力大小为河岸缓冲带>植被过滤带>生态浮岛>台地式石笼护岸。相比其它植物组合,乔灌木群落栽植对水体中营养盐净化最具有潜力。     

Small Multiorder BOD Reactions in Oxygen Sag Models

Wastewaters containing sugars are easily and rapidly biodegraded, which results in their exerting a short period of intense demand for dissolved oxygen (DO). Their carbonaceous biochemical oxygen demand (BOD) is described by an empirical multiorder decay reaction with an order less than one. Examples show calculations of multiorder BOD equation parameters from glucose and glutamic acid data and the effect of a wastewater on DO sag in a river.     

Fuzzy Waste Load Allocation Model: Simulation-Optimization Approach

The problem of waste load allocation (WLA) for water quality management of a river system is addressed with a simulation-optimization approach. The WLA model developed in the study provides the best compromise solutions to the pollution control agency (PCA) responsible for maintaining the water quality and the dischargers disposing pollutants into the river system. A previously developed fuzzy waste load allocation model (FWLAM) is extended to incorporate QUAL2E, a water quality simulation model developed by the U.S. Environmental Protection Agency for modeling the pollutant transport in a river. The imprecision associated with establishing water quality standards and the aspirations of the PCA and dischargers are quantified using fuzzy goals with appropriate membership functions. The membership functions of the fuzzy goals represent the variation of the goal satisfaction in the system. A genetic algorithim (GA) is used as an optimization tool to find optimal fraction removal levels to the dischargers and the corresponding satisfaction level. Because a GA is an unconstrained optimization tool, it is extended to handle constraints by complementing it with homomorphous mapping (HM), a constraint handling method for evolutionary algorithms. The GA directs the decision vector in an encoded form to HM. HM, after a few interactions with QUAL2E, redirects the decoded solution back to the GA. The GA assigns a fitness value to the feasible solution vector and applies operators to refine the solution. This interaction among the GA, HM, and QUAL2E continues until a prespecified criterion for global optimality is met. Application of the model is illustrated with a case study of the Tunga-Bhadra River in South India.     

Influence of Physical Forcing on Bottom-Water Dissolved Oxygen within Caloosahatchee River Estuary, Florida

Environmental Fluid Dynamics Code, a numerical estuarine and coastal ocean circulation hydrodynamic and eutrophication model, was used to simulate the distributions of dissolved oxygen (DO), salinity, water temperature, and nutrients in the Caloosahatchee River Estuary. Modeled DO, salinity, and water temperature were in good agreement with field observational data from the Florida Department of Environmental Protection and South Florida Water Management District. Sensitivity analyses identified the effects of river discharge, atmospheric winds, and tidal forcing on the spatial and temporal distributions of DO. Simulation results indicated that vertical mixing due to wind forcing increased the bottom DO concentration. River discharge enhanced stratification in deep locations but propagated vertical mixing in the shallow upper estuary. Finally, tidal forcing heavily influenced bottom layer DO concentrations throughout the whole river estuary.     

Oxygen Sag Models for Multiorder Biochemical Oxygen Demand Reactions

The empirical biochemical oxygen demand (BOD) equation is expressed as a multiorder reaction equation of order n, then is combined with the dissolved oxygen mass balance equation to give the differential form of an oxygen sag equation for small rivers and streams for which dispersion can be neglected. The value of n in the BOD reaction is restricted to values that are larger than one (first order). The dissolved oxygen sag equation is verified with two published dissolved oxygen sag models by setting n equal to 3/2 (three-halves order BOD reaction), and n equal to 2 (second order BOD reaction). The proposed dissolved oxygen sag equation may be applied to test the BOD and dissolved oxygen models in large, complex numerical models, such as models used in developing total maximum daily load recommendations. Examples show how the BOD reaction order affects the dissolved oxygen sag characteristics of a river.     

黄河水源污染对画匠营子水厂供水的影响

黄河是包头市的主要水源.本文分析了由于黄河过境流量减少及河水污染对画匠营子自来水总厂造成的影响,并对此提出了改进建议.     

基于GIS的土耳其国际保护区G(o)ksu河水质的调查与建模

Goksu Delta is an important wetland where the G(o)ksu River reaches to sea in the eastern of the town Tasucu-lce1. The delta is classified as a Wetland of Intemational Impor-tance according to the Ramsar Convention on Wetlands of International Importance. The amount of fertilizers used in this area was 7200 tons in 2006. These pollutants affect the surface and groundwater quality negatively. The intensively used fertilizers and pesticides contain not only N-and P compounds but also some heavy metals. The contents of all pol-lutants in surface waters were determined for four different seasons between 2006 and 2008 and with these data a Geographic Information System(GIS)has been constructed by using Map Info. From the photometric heavy metal analysis, it is inferred that the excess concen-tration of Fe, Ni, Mn, Mo and Cu at some locations is the cause of undesirable quality for drinking purposes. The source of excess concentration of various heavy metals is the agri-cultural activities and fertilizers. It is determined that in all periods between 2006 and 2008 the heavy metals and other pollutants in the fertilizers and pesticides transported easily to river water with irrigation return flow. The organic pollutants, including COD, BOD, NH3 and NO3 followed the sharply increasing trends from Silifke city to Mediterranean Sea. The water quality of G(o)ksu River is modeled and determined that the waste water discharge of 10,700 m3/day from Silifke city does not create a serious problem because of the high amount of flow rate of G(o)ksu River.     

Effect of non-point source pollution on water quality of the Weihe River

Non-point source pollution is an important factor that affects the water quality of the Weihe River. To study the effect of the pollution on the water quality of the Weihe River, five flood events and three normal discharge events during non-flood period were monitored from July to December in 2006, at the Lin-tong section. In order to identify how sediment influenced the water quality of the river, raw and supernatant samples taken from the monitored events were analyzed. Supernatant samples were siphoned from 5 cm below the water surface of the raw samples at the lab afterwards the raw samples were shaken up and laid for 30 minutes in the beakers. The results indicated that: 1) The concentrations of SS, COD, TP and TN in the raw samples from flood events were higher than those from normal discharge events. The higher values of the COD, TP and TN in the raw samples resulted from natural humic matters in surface soil. 2) The load transport rate of analyzed water quality indexes increased gradually to its maximum and then drop down, matching that in the discharge hydrograph. The concentrations of SS, NH3-N, NO2-N, NO3-N, COD, and TP in the raw samples increased initially and then decreased, while the concentration of dissolved orthophosphate and TN in the raw samples decreased gradually and then increased. The peak time of concentration and load transport rate of SS as well as COD, TP and TN in the raw samples were close to or lagged behind the time of peak flow.Generally, the peak time of concentration and load transport rate of dissolved orthophosphate,dissolved total-phosphate, NH3-N, NO2-N, and NO3-N occurred prior to the time of peak flow. 3) The mean concentration method was used to calculate the NPS pollution load at Lin-tong section, and the results are credible. In 2006, the proportions of the NPS pollution load to the total load for COD, TP,TN and inorganic nitrogen were more than 30%.     

Robotic Monitoring to Assess Impacts of Zebra Mussels and Assimilative Capacity for a River

Water quality impacts of zebra mussel metabolism over an infested 15?km reach of the Seneca River, N.Y., are documented, based on vertically and temporally detailed robotic monitoring at the reach boundaries during the summer through early fall intervals of 2?years. Substantial reductions over the study reach are documented for dissolved oxygen (DO), pH, fluorometric chlorophyll a, and turbidity, associated with the metabolism of this invader. Violations of New York State water quality standards for DO that would not be resolved by traditional manual monitoring programs were observed. The loss of assimilative capacity caused by the zebra mussel invasion is confounding rehabilitation efforts for a downstream polluted lake that had considered diversion of municipal effluent to the river. The critical role robotic monitoring units would play in an automated control system for an innovative strategy of time-variable river discharge of the effluent is described. Near-real time robotic monitoring provides a more detailed understanding of the impacts of zebra mussels on water quality than traditional less intensive manual measurements.     

Evaluating a Probabilistic Approach for Simulating Pathogen Removal at a Riverbank Filtration Site in India

In this paper, concentrations of pathogens in the influent and bank filtrate water at a riverbank filtration (RBF) site in Haridwar, India, are simulated by using a probabilistic approach. During the study of the RBF water quality in Haridwar in 2005–2006, it was observed that the river water does not meet World Health Organization and other Bureau of Indian Standards requirements for drinking water quality, especially with respect to bacteriological water quality, i.e., total coliform and fecal coliform levels, and therefore, changes to the river water quality as it moves to an infiltration well are of much relevance. By using the river water quality and the quality of abstracted water from nearby pumping wells, a probabilistic approach is used to study the variation of probability of clogging under different bacteriological qualities of source water. It is observed that the probability of clogging the pores varies with the natural logarithm of the concentrations of pathogens in source water, and the probabilistic approach has the potential to be used to simulate variations in pathogens in riverbank filtrate.     

后污染期龙江河底泥中镉铅的形态分布及风险评价

为了解龙江河镉污染事件后污染期沉积物中镉、铅的形态分布和风险状况,对龙江河拉浪、怀远、宜州、湖长4个河段的底泥进行采样分析,用Tessier逐级浸提法测试镉、铅的形态及含量,用地累积指数法和潜在生态风险指数法评价污染程度和风险等级。结果显示,龙江河底泥中镉、铅主要以氢氧化物、碳酸盐、硫化物的形态存在,氢氧化物、碳酸盐沿河均匀分布,硫化物及总镉、总铅的含量沿河逐渐降低。拉浪、怀远河段镉的地累积指数等级为3级,属中度污染,与2012年3月和7月的6级极重污染相比污染程度已大幅下降;宜州、湖长河段镉的污染等级为2级,属偏中污染。拉浪河段底泥中镉的潜在生态风险等级为较重风险,怀远、宜州、湖长河段镉的潜在生态风险为中风险等级。对于底泥中的铅,4个河段均处于无污染状态和低风险等级。     

赣江上游河道氮污染分析评价

为研究赣江上游-桃江流域水质污染分布状况,基于平水期在桃江流域采集的167个水样,通过现场和室内分析测定,并运用内梅罗综合污染指数和单因子污染指数评价法对流域的硝氮和氨氮污染状况进行评价.结果表明:① 桃江干流和大部分支流pH值都在地表水环境质量标准限值范围内,但濂江17个采样点中,有4个采样点受小型电站和酿酒厂的影响...     

Minimizing the Ecological Risk of Combined-Sewer Overflows in an Urban River System by a System-Based Approach

As urban and suburban areas expand, the problem of sewage disposal spreads as well. Inappropriate planning of a sewage management system could impair water quality, destroy habitat, and threaten public health. Simply building a sewage interceptor system along the urban river corridor to handle the wastewater effluents without regard to the impacts from combined-sewer overflows (CSOs) in the storm events cannot fulfill the ultimate goal of environmental restoration in the receiving water body. This study therefore carries out a system-based assessment to search for the optimal operating strategy of the interceptor facilities with respect to biocomplexity or biodiversity in an urban river system. In particular, it focuses on the richness of the fish community in the biological systems, the effect of stress on the fish community by storm events, and their capacity for adaptive behavior in response to the CSOs’ impact in the Love River estuarine system, South Taiwan. By integrating the biological indicators in an environmental context, two simulation models describing the quality and quantity of storm water and their impact on the river water quality are calibrated and verified. The interactions of natural systems and engineered systems covering both spatial and temporal aspects can then be explored in terms of the predicted levels of dissoved oxygen (DO) along the river reaches so as to strengthen an ultimate optimal search for the best operational alternative for the interceptor system. In view of the inherent complexity of integrating simulation outputs at various scales to aid in building the optimization step, three regression submodels were derived beforehand. These submodels present a high potential for exhibiting, eliciting, and summarizing the nonlinear behavior between the CSO impacts and the DO levels in the river reaches. With the aid of such findings, this study finally applies a linear programming model to determine the optimal size of a constructed storage pond (i.e., a detention pond), based on several types of storm events in the study area. This is proved essential for minimizing the ecological risk in such a way so as to indirectly improve the biodiversity in the estuarine river system.     

Optimal Wasteload Allocation Procedure for Achieving Dissolved Oxygen Water Quality Objectives. II: Optimal Load Control

This paper presents the development of an efficient strategy for achieving in-stream dissolved oxygen (DO) water quality standards (WQSs) via optimized point-load control strategies using the adjoint method. To this end, a least-squares-type objective function is formulated that measures the difference between desired (WQSs) and current DO concentrations at strategically selected monitoring points in the domain. The goal is to minimize the difference between actual DO concentration and the WQS, hence allowing time-variant loadings to utilize the assimilative capacity of the receiving water body at an optimal level. Time-variant discharge rates for a number of discharge locations are considered as control parameters, while different zone-specific critical DO levels are imposed as constraints. The selection of the control is kept flexible and a number of different scenarios are tested. First, only carbonaceous biochemical oxygen demand is used, which allows for a reduction of the number of equations that need to be solved. In the other tests, all constituents are switched on and different variables at each load node are selected as a control by first varying the concentrations individually, and then linking them through control of the volumetric flow rate. Optimization is achieved using a conjugate gradient search method, for which the gradients are computed through the solution of both the direct and adjoint problems. It is shown that the large amount of gradient information (parameter space has a dimension of several thousands) can be computed very efficiently using the adjoint, and that optimized results are achieved after only a few iterations irrespective of the initial guess. Computations are carried out using both two-dimensional model formulation applied to a long rectangular channel with varying width and slope and a model for the upper Potomac River estuary.     

Long-Term Simulation of Thermal Regime of Missouri River

Riverine water temperature extremes have typically been analyzed using event-based simulations, for example the 10-year 7-day low flows, combined with record-high air temperatures and other extreme conditions relevant to the location (e.g., maximum power generation). Using this combination of extreme conditions, one can estimate the maximum water temperature that may occur on the river. However, this method does not allow for calculation of, for example, the probability of a given temperature exceedence, or the average duration of such an excursion event. Alternatively, long-term continuous simulation using historical and physically representative reconstructed data records provides a large database of realistic events, which can be used to analyze the thermal regime of a river and its variability under current and changing conditions. This study applies such a procedure to the Missouri River between Gavins Point Dam at Yankton, S.D., and Rulo, Nebr. Along this reach, the thermal regime is influenced by six power installations, which release heated condenser cooling water to the main stem. Several scenarios were simulated numerically with the one-dimensional (1D) CHARIMA model to examine the effects of current power generation, as well as changing operational, hydrologic, and climatological conditions on the river thermal regime. Model simulations revealed that climate change and increased power demand may significantly affect the thermal regime of the Missouri River; however, the scenarios simulated in this study did not result in water temperatures that exceed the current temperature standards.