Jean-Michel Guldmann

International water resources allocation and conflicts: the case of the Euphrates and Tigris

This paper presents a linear programming model that allocates the waters of the Euphrates and Tigris rivers to irrigation, urban consumption, and on-stream hydroelectricity production in the three riparian countries (Turkey, Syria, and Iraq), by maximizing the aggregate net benefits from water uses while accounting for water-conveyance costs. The model represents, in network form, the system made of the two rivers and their various consumption, supply, and transshipment nodes, and accounts for evaporation and return flows. The constraints include water-conservation balances and maximum and minimum water consumption. The model is used to assess the economic consequences of various cooperation and noncooperation strategies that may be adopted by the riparian countries. Cooperative game-theory concepts (core and Shapley value) are used to identify stable water allocations, under which all three countries find it beneficial to cooperate. The results suggest that an allocation of the total benefits exists, under various scenarios of future energy prices and agricultural productivities, that makes this global cooperation attractive to all countries. Various research extensions are outlined.

Optimizing the natural gas supply mix of local distribution utilities

A large mixed-integer linear program (MILP) and a much smaller nonlinear programming (NLP) approximation of the MILP, involving simulation and response surface estimation via regression analysis, are proposed to solve the problem of the optimal selection of natural gas supply contracts by local gas distribution utilities. Each potential supply source is characterized by several price and nonprice parameters. Weather variability is the basic stochastic factor that drives the demand for gas by various market segments. The model minimizes the total cost of gas supply and market curtailment, and thus determines the size of the interruptible market. A numerical application of the methodology illustrates the excellent quality of the NLP approximation and the importance of the trade-offs between contract characteristics. A multi-temporal extension of the modeling methodology is outlined.

Competing destinations and intervening opportunities interaction models of inter-city telecommunication flows*

This research makes use of a large sample (600,000) of individual telephone calls between local exchanges (cities, villages) within a U.S. region. Callers and callees are identified by their 4-digit SIC (Standard Industrial Classification) code. The intersectoral and interlocational flows (number of messages and conversation minutes) are aggregated into major economic sectors (Agriculture, Manufacturing, Retail Trade ...., and Households), and are analyzed by estimating, in a simultaneous equation framework, spatial interaction models that account for (1) the role of the spatial structure, which reflects the competition and agglomeration effects that take place among the flow destinations, and (2) the role of the reverse flows, which reflect the process of information creation necessary to complete intersectoral economic transactions. A particular focus is set on Fotheringhams competing destinations model and Stoufers intervening opportunities model, while accounting for the effects of place hierarchy. A theoretical framework is presented, to guide the interpretation of the empirical results and their policy implications regarding the impacts of telecommunications deregulation, transportation and telecommunications interactions, and the role of information technologies in fostering the development of rural and peripheral areas.

Optimizing Patterns of Land Use to Reduce Peak Runoff Flow and Nonpoint Source Pollution with an Integrated Hydrological and Land- Use Model

Abstract The goal of this study is to develop and apply a methodology for delineating optimal land-use patterns that minimize peak runoff flow at watershed outlets by coupling a hydrological model and a land-use model. Under the assumption supported in prior research that nonpoint source (NPS) pollution is positively correlated with surface runoff volume, the model then yields land-use patterns that minimize nonpoint source pollution. A hydrological simulation model is developed with a modified and spatially explicit Soil Conservation Service (SCS) curve number method to analyze the geographical impacts of land uses. An optimization algorithm is integrated with the simulation model to evaluate different land-use patterns and their response to rainfall runoff events, and to search for optimal land-use patterns. This approach, applied to the southwestern basin of Lake Erie, Old Woman Creek Watershed (Ohio), yields optimal land-use patterns that reduce the peak runoff rate by 15%–20% under 1-, 2-, 5-, and 10...

Impacts of Urban Containment Policies on the Spatial Structure of US Metropolitan Areas

This paper examines the impacts of different types of urban containment policies (UCPs) on the spatial structure of US metropolitan areas, with a particular focus on UCP tightness. These UCPs include state-mandated urban growth boundaries (UGBs), locally adopted urban growth boundaries and urban service areas (USAs). Population and employment density gradients, taken as concentration measures, are estimated for 135 metropolitan areas and are then used in a simultaneous equation model to assess the impacts of different UCPs on metropolitan spatial structure. The results suggest that state-mandated ‘strong’ UGBs more effectively promote growth within the boundaries than locally adopted UGBs or USAs.

Simulating urban population density with a gravity-based model

Abstract Theoretical justifications for the negative exponential urban density function were first proposed by urban economists, although some of their foundations have been criticized. From the geographers perspective, the gravity-based model reported in this research uses a well-known concept (the “potential”) to offer an alternative explanation. Using numerical analysis techniques, the model simulates various urban density patterns. By varying the models parameters (the distance friction coefficient β and the city size), the numerical simulations do confirm two important empirical findings: the flattening of density gradients over time owing to transportation improvements, and flatter gradients in larger cities. The observed relationship between the β value and the urban density gradient, as established by this research, opens an avenue for empirical testing.

Economies of scale and density in local telephone networks

Abstract The production structure of local telephone networks is analyzed with a translog cost function estimated with cross-sectional data on a sample of 44 small local exchange companies (LECs). The output vector includes the number of stations served and the service territory area. Economies of scale are exhausted beyond 992 stations with growth through territorial expansion. The threshold for expansion through densification is 51,053 stations. These results suggest that the optimal LECs size is small, and that competition may be the most efficient form of production organization for medium to large markets in rural and low-density urban settings.

Costs of abandoned coal mine reclamation and associated recreation benefits in Ohio.

Two hundred years of coal mining in Ohio have degraded land and water resources, imposing social costs on its citizens. An interdisciplinary approach employing hydrology, geographic information systems, and a recreation visitation function model, is used to estimate the damages from upstream coal mining to lakes in Ohio. The estimated recreational damages to five of the coal-mining-impacted lakes, using dissolved sulfate as coal-mining-impact indicator, amount to

MODELING THE STRUCTURE OF GAS DISTRIBUTION COSTS IN URBAN AREAS

21 Million per year. Post-reclamation recreational benefits from reducing sulfate concentrations by 6.5% and 15% in the five impacted lakes were estimated to range from

Land-Use Optimization for Controlling Peak Flow Discharge and Nonpoint Source Water Pollution

1.89 to