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1.
R Fenz A P Blaschke M Clara H Kroiss D Mascher M Zessner 《Water science and technology》2005,52(9):209-217
The anti-epileptic drug carbamazepine was used as marker species in wastewater to identify and quantify sewer exfiltration. In several studies carbamazepine turned out to be hardly removed in wastewater treatment and not or just slightly attenuated during bank infiltration. Concentrations in wastewater are generally 1000 times higher than the limit of quantification. In contrast to many other marker species a "young" drug as carbamazepine is discharged to the environment only by wastewater. The results from this study carried out in Linz, Austria indicate an average exfiltration rate, expressed as percentage of the dry weather flow that is lost on the city-wide scale, of 1%. This rate is lower than sewage losses reported in most other studies which attempted to quantify exfiltration on the basis of groundwater pollution. However, it was also possible to identify one area with significant higher sewage losses. 相似文献
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Different approaches for quantification of pollution loads discharged from combined sewer networks into surface water bodies have been observed over the last few years and decades, but a large number of unresolved problems still remain. Many monitoring campaigns have been based on manual or automated spot sampling - with the long known limitations of this method such as sampling errors and errors due to sample conservation, transport and preparation. On the other hand, only recently have sensors became available which are suitable for continuous application in sewer networks. A large number of practical problems still have to be solved before continuous monitoring in sewer networks will be successful. Additionally, most of the applicable sensors are based on surrogate methods which results in a considerable effort for reference measurements for sensor calibration. Finally, it has to be considered that, depending on the sewer network topography, deposition and remobilisation of pollutants varies considerably, which limits the generality of monitoring results and, subsequently, their applicability as a base for the design of storm water tanks or combined sewer overflows (CSO). A monitoring station for continuous monitoring of load discharges from a CSO has been installed and operated for more than one year. The design and equipment of the measurement station, operational experiences and results are given in this paper. 相似文献
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As the decommissioning of dams becomes a common restoration technique, decisions about dam removals must be based on sound predictions of expected outcomes. Results of past and ongoing dam removal monitoring are an important source of information that practitioners may utilize to evolve predictive and decision‐making tools, emphasizing the need for thorough and defensible documentation of dam removal outcomes. However, as dam removals challenge many basic assumptions of conventional experimental designs and data analysis techniques, the quality of information available to aid decision‐making may be questionable or misleading. Nevertheless, some study design principles and analysis procedures may be robust to the challenges presented by dam removal research. To assist managers in undertaking dam removal monitoring, this article discusses the assets and limitations of monitoring and analysis options available for dam removal studies, with emphasis on selecting a rigorous experimental design and determining significance of results. As the chosen monitoring design will influence the appropriateness of applying standard analytical methods, particularly statistical hypothesis testing, researchers should carefully consider constraints inherent to dam removal studies when designing a monitoring plan and assigning significance to observed changes. Ecological significance is often the most justifiable method for framing significance of dam removal outcomes, though it may be complicated by identification of environmentally significant thresholds. Another alternative is evaluation of the practical significance of results, when observed changes exceed measurement error and background variability. Establishing practical significance may be informative when statistical and ecological significance is inappropriate or impossible to determine. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Two decision models, one for determining optimal systems for rainwater management and the other for allocating additional water supplies from managed rainfall in conjunction with irrigation water, are formulated. The application of a rainwater management model to the command and to a watercourse, decides the minimum cost activities to manage rainwater. The output from the first model is used as the input in the second model which optimally allocates water to competing crops. It has been shown that 80% of rainwater could be managed economically in rice fields and in storage underground through artificial recharge. Optimal allocation of managed rainwater in conjunction with irrigation water increases the income of the project area to the extent of 14%.List of symbols AER
Total available energy kWh
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B
max
Maximized value of the objective function, Rs
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C
W
Cost of canal water, Rs/103 m3
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C
i
Cost of managing rainwater through activityi, Rs/103/m3
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C
min
Minimized cost of managing surplus rainwater, Rs
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C
RF
Average cost of managed rainwater through activityi, Rs/103 m3
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E
i
Energy consumption in rainwater management activityi, kWh/103 m3 (only energy required for pumping water is considered)
- FLS
Available capacity for fallow land storage, 103 m3
- FPS
Total storage in lined and unlined farm ponds, 103 m3
- GWR
Runoff diversion for artificial recharge through inverted tubewells, 103 m3
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i
A suffix for management activities having values 1,2,3,...,
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j
Crop index having values 1,2,3,...,
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k
Index for crop season, 1=kharif (summer) and 2=rabi(winter)
- MRF
Maximum rainfall surplus (runoff) available for management. (Runoff value at a 5-year return period was adopted)
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P
j
Income from crop activityj, Rs/ha
- RFL
Storage in fallow alkali land, 103 m3
- RFS
Storage in rice fields up to various depths, 103 m3
- RWM
i
Volume of rainwater managed through activityi, 103 m3
- VCW
Volume of canal water, 103 m3
- VGW
Volume of ground water, 103 m3
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X
j
Area under cropj, ha. 相似文献
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Akihiro Nagaiwa Katsushi Settsu Fumiyuki Nakajima Hiroaki Furumai 《Water science and technology》2007,55(4):75-83
To reduce the CSO (Combined Sewer Overflow) pollutant discharge, one of the effective options is cleaning of sewer pipes before rainfall events. To maximize the efficiency, identification of pipes to be cleaned is necessary. In this study, we discussed the location of pipe deposit in dry weather in a combined sewer system using a distributed model and investigated the effect of pipe cleaning to reduce the pollutant load from the CSO. First we simulated the dry weather flow in a combined sewer system. The pipe deposit distribution in the network was estimated after 3 days of dry weather period. Several specific pipes with structural defect and upper end pipes tend to have an accumulation of deposit. Wet weather simulations were conducted with and without pipe cleaning in rainfall events with different patterns. The SS loads in CSO with and without the pipe cleaning were compared. The difference in the estimated loads was interpreted as the contribution of wash-off in the cleaned pipe. The effect of pipe cleaning on reduction of the CSO pollutant load was quantitatively evaluated (e.g. the cleaning of one specific pipe could reduce 22% of total CSO load). The CSO simulations containing pipe cleaning options revealed that identification of pipes with accumulated deposit using the distributed model is very useful and informative to evaluate the applicability of pipe cleaning option for CSO pollutant reduction. 相似文献
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Nitrification kinetics are important for process design, optimization, and capacity rating of activated sludge wastewater treatment plants. A Water Environment Research Foundation (WERF) project on Methods for Wastewater Characterization in Activated Sludge Modeling (WERF, 2003) focused significantly on the development of procedures for measuring the nitrifier maximum specific growth rate, micro(AUT). In addition, the importance of (and lack of data for) the nitrifier decay rate, b(AUT), was identified. This paper describes three bench-scale methods for measuring micro(AUT): the Low F/M SBR, Washout and High F/M methods. During the WERF project, the importance of pH and temperature control was investigated briefly; this paper summarizes further experimental work performed to address these issues. A summary of micro(AUT) measurements in a number of locations and using the different measurement techniques is provided. 相似文献
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This paper developes the WWTP operation decision support system (ODSS) to simulate the dynamic behavior of the WWTP treatment process based on ASMs (activated sludge models) and WWTP experiential knowledge. The novel structure and functions of ODSS can offer more flexible and general instructions to the WWTP operations. The three independent sub-systems, namely expert system, simulation system and training system, can cooperate to achieve many more functions such as operation alert, fault diagnosis, process simulation and so forth. The expert system based on the dynamic simulation, an essential part of WWTP ODSS, has been proved to be feasible and effective by the implementation at Fang Zhuang WWTP. Our results indicated that the WWTP ODSS has significant potential for improving plant performance and reducing treatment costs by assisting the operators at the decision-making level. 相似文献
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主要介绍了洪屏上水库主坝、西副坝、西南副坝安全监测系统设计,包括变形监测、渗流监测、应力应变监测等,并对蓄水初期监测成果进行了简要分析。 相似文献
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C J J Eijgenraam 《Water science and technology》2007,56(4):113-124
After the flood disaster in 1953 in the southwestern part of the Netherlands, Van Dantzig tried to solve the economic decision problem concerning the optimal height of dikes. His solution has a fixed probability of flooding after each investment. However, when there is economic growth, not the probability of flooding but the expected yearly loss by flooding is the key variable in the real optimal safety strategy. Under some conditions, it is optimal to keep this expected loss within a constant interval. Therefore, when the potential damage increases by economic growth, the flooding probability has to decline in the course of time in order to keep the expected loss between the fixed boundaries. The purpose of the paper is to show the implications of the optimal solution in case there are differences between costs and benefits among dike-ring areas. Further, the paper focuses on the translation of the theoretical results into new legal standards that can work well in practice. 相似文献
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T Frehmann T Mietzel R Kutzner B Spengler W F Geiger 《Water science and technology》2004,50(11):89-96
A special structure of combined sewer overflow tanks is the inline storage sewer with downstream discharge (SKU). This layout has the advantage that besides the sewer system, no other structures are required for storm water treatment. Consequently only very little space is required and compared to combined sewer overflow tanks, there is an enormous potential in reducing costs during construction. To investigate the efficiency of an inline storage sewer, a monitoring station was established in Dortmund-Scharnhorst, Germany. The monitoring station was in operation for a period of 2.5 years. Within this period water samples were taken during a total of 20 discharge events. Besides the complete hydraulic data collection, seven water samplers took more than 5,000 water samples during dry and wet weather. This adds up to a total of more than 20,000 individual lab analyses. The average of the total efficiency for the SKU-West is 86%. 29% of this efficiency can be attributed to the throttle flow. The remaining 57% can be divided into a part of 48% that can be attributed to the process storage and 9% that can be attributed to sedimentation and erosion process. 相似文献
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系统总结评价了南水北调西线工程设计方案。遵循自流调水、高水低走、纵向坡降均一化、梯级水库库容调节、多路联合调水原则,利用地理信息系统空间分析功能和水力学规划求解方法,计算设计了以米林桑白-岷县铁关门线为主线的高海拔、中高海拔和中低海拔3线联合的最优调水方案,最大调水量为1 777. 4×108m3/a。通过同红旗河方案比较,发现桑白-铁关门线调水方案规避了红旗河方案的缺点,具有线路短,纵向坡降大,交通便利的优点,并且避开了自然保护区和地质灾害高风险区。认为以中低海拔线为主的多线联合调水方案应当成为西线调水的首选方案。 相似文献
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Use of climate scenarios to aid in decision analysis for interannual water supply planning 总被引:1,自引:0,他引:1
This work addresses the issue of climate change in the context of water resource planning on the time scale of a few years.
Planning on this time scale generally ignores the role of climate change. However, where the climate of a region has already
shifted, the use of historical data for planning purposes may be misleading. In order to test this, a case study is conducted
for a region, the Australian Capital Territory, where long term drought is raising concerns of a possible climate shift. The
issue is cast in terms of a particular planning decision; the option to augment water supply in the next few years to hedge
against the drought persisting. A set of climate scenarios are constructed for the region corresponding to the historical
climate regime and to regimes where progressively greater levels of change are assumed to have already taken place (5%, 10%,
20% reductions in mean rainfall). Probabilities of the drought persisting are calculated for each of the scenarios. The results
show substantial increases in the probability of the drought persisting for even moderate reductions in mean rainfall. The
sensitivity of the decision to augment supply to the scenario results depends ultimately on the planners tolerable thresholds
for the probability of the drought persisting. The use of different scenarios enables planners to explore the sensitivity
of the decision in terms of their risk tolerance to ongoing drought and to their degree of belief in each of the scenarios
tested. 相似文献
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Kelly F. Robinson Mark DuFour Michael Jones Seth Herbst Tammy Newcomb James Boase Travis Brenden Duane Chapman John Dettmers James Francis Travis Hartman Patrick Kočovský Brian Locke Christine Mayer Jeff Tyson 《Journal of Great Lakes research》2021,47(1):108-119
Decisions about invasive species control and eradication can be difficult because of uncertainty in population demographics, movement ecology, and effectiveness of potential response actions. These decisions often include multiple stakeholders and management entities with potentially different objectives, management priorities, and jurisdictional authority. We provide a case study of using multi-party, collaborative decision analysis to aid decision makers in determining objectives and control actions for invasive grass carp (Ctenopharyngodon idella) in Lake Erie. Creating this process required binational (Canada-United States) and multi-state/provincial collaboration to craft a shared problem statement, establish objectives related to ecological, economic, and social concerns, determine potential response actions, and evaluate consequences and tradeoffs of these actions. We used participatory modeling and expert elicitation to evaluate the effectiveness of control scenarios that varied in action type (i.e., removal efforts and spawning barriers) and the temporal and spatial application of these actions. Using a matrix population model parameterized for western Lake Erie grass carp, we found that removal efforts concentrated in areas of high catchability, when paired with a spawning barrier on the Sandusky River, Ohio, USA, could effectively control grass carp in Lake Erie, if all assumptions are met. We determined a set of key uncertainties regarding gear catchability and current population size that have led to the transition to an adaptive management process. In addition, our work formed the basis for grass carp management plans for the states of Michigan and Ohio and has provided a means for collaboration among agencies for effective application of control efforts. 相似文献