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The article proposes a formula for calculating scheme viscosity, which manifests itself in calculations using implicit schemes for calculating the transfer of matter and momentum. The study aims to substantiate the structure of the formula for calculating the scheme viscosity using implicit schemes for calculating the mass and momentum transfer equation. As a result of the study, the structure of the formula for calculating the scheme viscosity for implicit schemes for solving the transfer equation was determined. The accuracy of the formula was checked on a test example. It is substantiated that by all possible means, it is necessary to avoid using implicit schemes when solving problems of small-scale circulation within urban areas. The manifestation of scheme viscosity in calculations of small-scale circulation, in which small pressure drops provide air movement, is unacceptable due to the many times the greater effect of scheme viscosity over natural viscosity.

The finite-difference scheme of directed differences (the Courant-Isaacson-Ries scheme), which is widely used in the practice of aerohydrodynamic calculations, is studied theoretically and on the example of test problems. We applied the commonly used in practice Courant-Isakson-Ries directional difference scheme that allowed us to find and show distributions of velocities where the laws of the matter conservation are violated in the calculations in solving the matter conservation equations or the correspondence of the obtained solutions to the most general practical understandings on the essence of the matter transfer. A scheme free from the shortcomings of the Courant-Isaacson-Ries scheme has been constructed, tested, and proposed for use in aerohydrodynamic calculations by the finite difference method. Moreover, all the valuable properties of this well-known scheme are preserved. Among the maintained properties: are transportability, conservatism, stability in calculations, invariance, and adequacy of the essence of the physical phenomenon of the transfer of matter in space. The disadvantages of the new finite-difference scheme proposed for solving the equations of conservation of matter should be considered: an increase in the required RAM for storing electronic means of calculating information about the velocity field in memory and an increase in the number of calculations needed.

By signing a water sharing agreement (WSA), countries agree to release an amount of river water in exchange for a negotiated compensation. We examine the vulnerability of such agreements to reduced water flows. Among all WSAs that are acceptable to riparian countries, we find out the one which is self-enforced under the most severe drought scenarios. The so-called upstream incremental WSA assigns to each country its marginal contribution to its followers in the river. Its mirror image, the downstream incremental WSA, is not sustainable to reduced flow at the source. Self-enforcement problems can be solved by setting water releases and compensations contingent to water flow. We apply our analysis to the Aral Sea Basin. We compute the upstream incremental compensations for the Bishkek agreement and asses its vulnerability with historical flows. © 2013 Elsevier Inc.

In this paper we offer a negotiation and cooperative game theory application to international water in the classroom. A simulation game was developed for the Aral Sea water dispute as part of a textbook prepared for teaching a diverse group of students a graduate-level International Water course. A condensed version of the Aral Sea Basin water dispute and hydrology was prepared. The game allows students to realize the complexity of hydrology and geography, the linkage between hydrology and conflict and cooperation, and the impact of external factors, such as climate change, on the extent of the conflict and its likely resolution. The game was used to simulate negotiations between a subset of the basin riparians, demonstrating the value of information in negotiation. Various cooperative game theory concepts were demonstrated and applied by students through a set of assignments representing a variety of likely states of nature and various development interventions. (Contains 4 figures, 2 tables and 8 notes.)

The development of relational databases from which simulation models can access data needed to describe the systems being modeled is fundamental to integrated river basin management, especially in shared, transboundary basins. Creating a geographically referenced database, a geodatabase, for the Rio Grande/Rio Bravo Basin represents the first major attempt to establish a more complete understanding of the basin as a whole, using both Mexican and United States geospatial and temporal water resources data. From the geodatabase, it is possible to obtain information about climatology, water availability, water uses, hydraulic infrastructure, and watershed properties in the basin. These data can be used in simulation models to calculate the state of basin water availability under different climatic and development scenarios and management plans in the future. This geodatabase is intended to be a tool to assist in sharing data to enhance binational cooperation between Mexico and the United States concerning water in this basin, providing accurate and reliable data necessary for analysis and resolution of water resources issues. DOI: 10.1061(ASCE)0733-9496(2007)133:5(416) CE Database subject headings: River basins; Texas; Water resources; Geographic information system; Databases; Water management.

The interdisciplinary nature of water resources problems requires the integration of technical, economic, environmental, social, and legal aspects into a coherent analytical framework. This paper presents the development of a new integrated hydrologic-agronomic-economic model in the context of a river basin in which irrigation is the dominant water use and irrigation-induced salinity presents a major environmental problem. The model's main advantage is its ability to reflect the interrelationships between essential hydrologic, agronomic, and economic components and to explore both economic and environmental consequences of various policy choices. All model components are incorporated into a single consistent model, which is solved in its entirety by a simple but effective decomposition approach. The model is applied to a case study of water management in the Syr Darya River basin in Central Asia. CE Database keywords: Water resources management; River basins; Irrigation; Optimization; Economic analysis.

Water saturation in the vadose zone is an important parameter for many nonaqueous phase liquid (NAPL) remediation technologies. Conventional soil boring analyses may not provide accurate average water saturation data. Previous studies have shown that a partitioning interwell tracer test (PITT) can provide an accurate estimate of average subsurface NAPL saturations. The PITT is proposed as a suitable technology for estimating average subsurface water saturations. In this research, difluoromethane was evaluated as a suitable tracer compound to partition among air, water, and NAPL phases. Method of moments analyses were used to develop equations necessary to determine water saturations from difluoromethane PITT results. One-dimensional column experiments provided air-water and air-NAPL partition coefficient data for difluoromethane. Difluoromethane is shown to be a suitable tracer for use in field PITTs to predict water saturations in the vadose zone.

This paper describes laboratory research conducted to investigate the performance of partitioning tracers for the detection of nonaqueous-phase liquids (NAPLs) in vadose zones. Once evaluated, the tracers may be used for volume estimation of NAPLs and remediation performance assessment of vadose zones. These laboratory studies used glass chromatography columns packed with: (1) Ottawa sand; and then (2) in a separate experiment, soil extracted from the Chemical Waste Landfill at Sandia National Laboratories. The columns were prepared in a manner that resulted in a three-phase system of air, water, and NAPL in the columns. Conservative and partitioning gas tracers were injected into the columns, and their elution concentrations were analyzed. The method of moments was used to estimate partition coefficients between the air and NAPL phases for each of the tracers. The partition coefficients and retardation factors, also estimated during the study, are used to select appropriate tracers for NAPL detection. This research identified several suitable perfluorocarbon tracers and demonstrated the feasibility of using partitioning tracers as a tool for NAPL detection in the vadose zone.

Water resources planners and managers are continually faced with decisions to be made under uncertainty. In planning problems such as water supply, flood control, and ground-water remediation, the tradeoffs among expected cost, cost variability, and system performance and reliability must be assessed amidst inherent variability and imperfect information. Robust optimization (RO) is introduced as a framework for evaluating these trade-offs and controlling the effects of uncertainty in water resources screening models. Upon the introduction of scenarios, which represent realizations of the random parameters in the model, two types of robustness are defined: a policy is optimality-robust if it remains optimal or nearly optimal for all scenarios, and feasibility-robust if it remains feasible or nearly feasible for all scenarios. Applications to urban water transfer planning and ground-water quality management are presented, with optimality robustness related to cost variability and feasibility robustness related to system reliability. Results show that RO can be a useful framework for evaluating the intrinsic trade-offs involving risk and finding solutions that hedge against inherent and parameter uncertainty.

A pump-and-treat system design methodology has been developed which combines well field and treatment plant design processes to create a more efficient overall optimal systems for remediating contaminated ground water. This ground-water management model uses a nonlinear programming algorithm, a treatment process model and ground-water flow and mass transport simulator. The model is used to determine the minimum cost design of the combined pumping and treatment of the remediation system, including fixed costs of system construction, installation, operation and maintenance.

Multigrid methods use a series of successively coarser grids to accelerate the solution of equations arising from the numerical solution of partial differential equations. A grid-cell-based geographic information system (GIS) with a map algebra language is capable of displaying and manipulating spatial data and attributes and handling the data arrays and results arising in ground-water simulation problems. To examine the efficacy of GIS to solve ground-water flow problems, we have performed ground-water modeling directly within a GIS without going outside the system for model solution. We have applied the multigrid method to solve steady ground-water flow problems in heterogeneous aquifers. Execution times for the GIS-multigrid approach using simple iterative techniques greatly exceed those of traditional ground-water simulation models due to the creation of temporary grids for intermediate calculations during the simulation. Efficient handling of boundary conditions is another difficult problem in GIS grid-cell-based modeling.

The feasibility of using an expert geographic information system (GIS) for long-term regional water-resources planning is evaluated through a case study examining an existing regional water-supply system. This system is comprised of an expert system that embodies the logical rules and expertise of water-resources planning experts as well as a geographic information system that stores and analyzes spatially distributed data. Normal water-demand forecasts and water-supply data along with appropriate analysis routines are used in this new planning tool, which attempts to follow the logic of current methods and permit plans to be updated and alternatives to be analyzed more rapidly. An example application of the system is presented which analyzes the existing water supply system for the Corpus Christi, Tex., area. Given annual yields for the reservoirs, water-demand forecasts, and institutional requirements, the expert GIS calculates potential water-supply deficits or excesses in the region over a 50-year planning horizon, and suggests efficient and cost-effective alternatives for developing additional water supplies in the event that deficits occur.

The Himalayas of South Asia are home to many glaciers that are retreating due to climate change and causing the formation of large glacial lakes in their absence. These lakes are held in place by naturally deposited moraine dams that are potentially unstable. Specifically, an impulse wave generated by an avalanche or landslide entering the lake can destabilize the moraine dam, thereby causing a catastrophic failure of the moraine and a glacial lake outburst flood (GLOF). Imja-Lhotse Shar glacier is amongst the glaciers experiencing the highest rate of mass loss in the Mount Everest region, which has contributed to the expansion of Imja Tsho. A GLOF from this lake may have the potential to cause catastrophic damage to downstream villages, threatening both property and human life. Therefore, it is essential to understand the processes that could trigger a flood and quantify the potential downstream impacts. The avalanche-induced GLOF process chain was modeled using the output of one component of the chain as input to the next. First, the volume and momentum of various avalanches entering the lake were calculated using RAMMS. Next, the avalanche-induced waves were simulated using BASEMENT and validated with empirical equations to ensure the proper transfer of momentum from the avalanche to the lake. With BASEMENT, the ensuing moraine erosion and downstream flooding was modeled, which was used to generate hazard maps downstream. Moraine erosion was calculated for two geomorphologic models: one site-specific using field data and another worst-case based on past literature that is applicable to lakes in the greater region. Neither case resulted in flooding outside the river channel at downstream villages. The worst-case model resulted in some moraine erosion and increased channelization of the lake outlet, which yielded greater discharge downstream but no catastrophic collapse. The site-specific model generated similar results, but with very little erosion and a smaller downstream discharge. These results indicated that Imja Tsho is unlikely to produce a catastrophic GLOF due to an avalanche in the near future, although some hazard exists within the downstream river channel, necessitating continued monitoring of the lake. Furthermore, these models were designed for ease and flexibility so that they can be adopted by a wide range of stakeholders and appropriated for other lakes in the region. [ABSTRACT FROM AUTHOR]

This paper studies the lake dynamics for avalanche-triggered glacial lake outburst floods (GLOFs) in the Cordillera Blanca mountain range in Ancash, Peru. As new glacial lakes emerge and existing lakes continue to grow, they pose an increasing risk of GLOFs that can be catastrophic to the communities living downstream. In this work, Lake Palcacocha is used as a case study to analyze the upper watershed processes that typically comprise a GLOF event, specifically the lake dynamics when an avalanche produces a large tsunami-like wave that might overtop and erode the lake-damming moraine. Dynamics of avalanche-generated impulse waves were investigated through three-dimensional hydrodynamic lake simulations of potential GLOF scenarios at Lake Palcacocha, Peru. Wave generation from avalanche impact was simulated using two different boundary condition methods. Representation of an avalanche as water flowing into the lake generally resulted in higher peak flows and overtopping volumes than simulating the avalanche impact as mass-momentum inflow at the lake boundary. Three different scenarios of avalanche size were simulated for the current lake conditions, and all resulted in significant overtopping of the lake-damming moraine. The lake model was evaluated for sensitivity to turbulence model and grid resolution, and the uncertainty due to these model parameters is significantly less than that due to avalanche boundary condition characteristics. Although the lake model introduces significant uncertainty, the avalanche portion of the GLOF process chain is the greatest source of uncertainty. To aid in evaluation of hazard mitigation alternatives, two scenarios of lake lowering were investigated. While large avalanches produced significant overtopping waves for all lake-lowering scenarios, simulations suggest that it may be possible to contain waves generated from smaller avalanches if the surface of the lake is lowered. [ABSTRACT FROM AUTHOR]