Numerous groundwater vulnerability methods have been developed taking into consideration a variable number of factors. The most common techniques are based on calculation of an index expressing the protective effect of underground formations overlying the groundwaterresource. However, it has been shown that different overlay and index methods applied to the same system can yield dramatically dissimilar results (among others, Gogu et al., 2003). The limitation of most of these methods is related to their use of a qualitative definition of groundwater vulnerability, as opposed to a definition based on a quantitative description of contaminant migration. A process-based point of view is proposed and based on three factors describing a pollution event (Brouyère et al., 2001): (1) the transit time from the source to the target, (2) the duration of the contamination breakthrough at the target, (3) the ratio between the maximum concentration at the target to the released concentration at the contamination source.
This paper extends the work by Roseta Palma (2002, 2003), constructing a model in which the water users react to the policies of a water agency. The model describes a group of irrigating farmers using the same groundwaterresource. The fertilizer used by the farmers leaches into the groundwater and causes nitrate pollution, which is mitigated by the stock dilution eect and the natural decay rate of the contaminant. Farmers optimize their individual payos without considering the impact of their decisions on the stock of water and its quality. To ensure sus- tainable use of the resource, a water agency is in charge of regulating the quantity and quality of the groundwater. Regulation takes the form of taxes on water withdrawal and use of fertilizers and of a subsidy program for the use of nitrogen-xing plants. 3 It is assumed that the regulator
range of studies in the field. Our study possesses four main features. First, we propose a full characterization of the cost function, paying particular attention to the positivity of marginal costs, which leads us to use a "LambertW" specification in the derivation of the feedback solution. Next, in the experiment we mimic continuous time by allowing subjects to make their extraction decisions whenever they wish, with an actualization of the data (resource and payoffs) every second. Third, the infinite horizon is simulated through the computation of payoff as if time were endless. Finally, in order to classify the individual as exhibiting myopic, feedback or optimal behavior and to get around the weaknesses of the widely used Mean Squared Deviation (MSD) statistic, we combine it with Ordinary Least Squares (OLS) regressions and time series treatments. The full characterization of the cost function and the combination of MSD and OLS are con- tributions of the paper. The representation of continuous time and infinite payoff are features borrowed from recent papers in the literature. These four features form what we argue to be good practices when studying dynamic games of common-pool resources in a laboratory experiment. To our knowledge, we are the first to conduct an experimental study on differential games comparing the behavior of experimental subjects according to theoretical predictions, as well as combining a single agent and a multiple agent treat- ment in the same experiment. Results show that a significant percentage of agents are able to adopt the optimal extraction path, that few agents should be considered truly myopic, and that using the MSD alone to classify agents would be misleading for about half of the study participants.
The groundwater vulnerability assessment has recently become an increasingly important environment management tool for local governments. It allows for better understanding of the vulnerabilities associated with the pollution of local groundwater sub areas, according to local hydrological, geological or meteorological conditions. The adopted method was specifically developed for groundwater vulnerability DRASTIC method and it is a widely used in many cases of study (Aller et al., 1987; Saidi et al., 2009 and 2011;Rahman, 2008). The DRASTIC model is based on seven parameters, corresponding to the seven layers to be used as input parameters for modeling, including depth to water table (D), recharge (R), aquifer type (A), soil type (S), topography (T), impact of vadose zone (I) and conductivity (C). Vulnerability index is defined as a weighted sum of ratings of these parameters. The quality index calculation procedure, based on the water classification, was introduced to evaluate hydrochemical data.
discharge is partly related to underground floods (when the water table increases beyond the elevation of the streams bed).
The particularity of this karst aquifer lies in the man- agement of the water resource, which consists in pumping water directly within the karst conduit at a depth under the level of the spring outlet (overflow level of the spring) extracting only part of the naturally renewable stock. Therefore, after a period where only the natural overflow of the spring was used, until 1965, water was pumped in the spring down to -6.50 m below the overflow level of the spring. This method allowed pumping 800 l/s for Mont- pellier water supply, even when the natural outflow of the spring was lower than 200 l/s (Avias 1995). When the needs of Montpellier increased above 800 l/s, four deep wells were drilled. These wells reached the karst conduit feeding the spring, 48 m below the overflow level of the spring (17 mASL). Pumping these wells allows up to 2,000 l/s to be withdrawn under low-flow conditions, while the average annual pumping flow rate is 1,100 l/s (1988–2009). This type of management is possible as long as the mean pumped flow rate does not exceed the mean annual discharge of the spring that is about 2,200 l/s (Avias 1992). Note that the natural spring discharge displays a high inter-annual vari- ability as highlighted by extreme values for the discharge (after Drogue 1974) monitored before pumping within the spring: in 1952 (dry year, 590 mm annual rainfall) the mean annual discharge of the spring was estimated to be 1.5 m 3 /s, while it was estimated to be 2.8 m 3 /s in 1962 (wet year, 1,150 mm annual rainfall).
The modelling approach, involving the catchment-scale fully integrated surface- subsurface model, is described in Goderniaux et al. . Biased-corrected climate change scenarios are applied as input of the hydrological model to quantify their impact on groundwater resources. In Goderniaux et al. , the integrated model is used in combination with a stochastic daily weather generator (WG). This WG allowed generating a large number of equiprobable climate change scenarios representative of a full transient climate between 2010 and 2085. These scenarios enabled to account for the transient nature of the future climate change, and to assess the uncertainty related to the weather natural variability. The downscaling method considers changes in the climatic means, but also in the distribution of wet and dry days.
Various groundwater vulnerability methods have recently been developed. Considering groundwater quality issues, the most common techniques are based on calculation of an index expressing the protective effect (i.e. in terms of solute contaminant transport) of underground formations overlying the groundwaterresource (Gogu & Dassargues, 2000, Gogu et al., 2003)). However, there is a strong need for new methods giving more emphasis on the processes-based calculation of vulnerability indicators.
1. Context and Objectives
If a pollution is likely to occur somewhere in a catchment, what is the potential sensitivity of the groundwaterresource to this pollution?
Î Identify relevant questions to be answered and associated physically-based criteria for groundwater vulnerability assessment
The major objective of the present investigation was to 1) evaluate whether an interaction exists, at the level of the mentioned brownfield, between groundwater and surface water; 2) to assess the dynamics of such interactions and to quantify groundwater fluxes as the main potential vector of mobility of contaminants offsite; and 3) to give first pieces of answers on the fact that, despite important sources of BTEX (in particular benzene) have been clearly delineated in the contaminated site, these products have never been observed in groundwater downstream from the sources, in the direction of the Meuse River.
deﬁned over the individual’s consumption level, her eort and the compar- ison of her consumption with that of other members of the community. We identify two dimensions along which consumption externalities distort the e!cient extraction of resources. First, when eort is costly, envy distorts the marginal rate of substitution between consumption and eort. We call this the static/steady-state distortion. Since status-seeking individuals overvalue consumption, their willingness to exert eort in order to achieve additional consumption is higher than the e!cient level. As a consequence of this they over-exploit the resource, resulting in a steady-state stock that is lower than the e!cient stock of resources chosen by a central planner. Second, even when eort is costless, consumption externalities might distort the willing- ness to shift consumption through time, resulting in an ine!cient path of extraction. We call this the dynamic distortion. We explore the conditions under which these two distortions arise and we show that there exists an optimal tax scheme which induces the competitive agents to replicate the choices of the planner. The tax rate is positive and, in general, time-varying. We calibrate our model under widely used functional forms and ﬁnd that, under consumption externalities, the competitive steady-state stock of re- sources is less than two thirds of the e!cient stock. Moreover the welfare costs associated with this over-exploitation are very large, close to one third of the laissez-faire steady-state level of consumption. Finally we revisit two important topics in the natural resource literature: amenities and extinction. The intuition we developed with our general model carries through in these special cases: over-exploitation arises even when the natural resource gener- ates a variety of amenity services, and the possibility of extinction increases with consumption externalities.
Singh et al. (2015), authors use multiple criteria deci- sion making approach to evaluate alternative management options in dairy farming with water resource limitation as a constraint to satisfy. Many other applications re- lated to water resource management and/or sharing with sustainability stakes can be found in references cited in the above analyzed publications. The main characteristics that one can draw from previous mentioned studies are that, water resource sharing and/or management problems consist in optimizing many objectives, which objectives depend on multiple attributes of alternative options, and that many actors that we refer to as stakeholders’ concerns or preferences must be taken into account when deriving the resolution procedure. These problems therefore fall into a large framework known as multi-objectives / multi- attributes or criteria and group decision making problems. Most of the approaches (that in general consider only one aspect of that mentioned here) used to solve such problems up to now in the literature, consist in transforming the "multi" into mono using some aggregation approach in order to use the well established "mono" optimization’s algorithms that abound in optimization literature (Luen- berger (1984); Moré and Wiright (1993)) or in searching for Pareto (see Pareto (1896)) set and then choosing an "appropriate" alternative within this set when using some additional information or constraints. These approaches do not distinguish, in earlier stages of decision process, the diﬀerence that may exist between positive incentives of an alternative and its negative impact with regard to a given
Abstract: The classical resource reservation protocol (RSVP) is a flow-based signaling protocol used for reserving resources in the network for a given session. RSVP maintains state information for each reservation at every router along the path. Even though this protocol is very popular, he has some weaknesses. Indeed, RSVP does not include a bidirectional reservation process and it requires refresh messages to maintain the soft states in the routers for each session. In this paper, we propose a sender- oriented version of RSVP that can reserve the resources in both directions with only one message, thus reducing the delay for establishing the reservations. We also suggest a refreshment mechanism without any refresh message which could be applied to any soft states protocol. Simulation results show that the proposed protocol is approximately twice faster than RSVPv2 for establishing bidirectional reservations with almost no control overhead during the session.
High chargeability anomalies in
the vicinity of the spring Normalized chargeability appears to be a striking observable for the
presence of CO 2 -rich groundwater, as it combines information from
resistivity and chargeability domains. The only value of normalized chargeability however does not allow a distinction regarding the cause of
The importance of root discrimination in complex commu- nities such as forests is presumably important due to the great number of plant species having different functional adapta- tions. One important such adaptation relates to the ability of late successional plants to colonize, grow and develop in already established forest understorey (Messier et al. 1999; Humbert et al. 2007). Early-successional species require recent large gaps or totally disturbed sites to get established. There exist many known ecological and physiological dif- ferences between these two functional groups (review by Valladares & Niinemets 2008), but relatively little is known about the plants’ abilities to develop and grow roots in the presence of competing neighbours. Our aim in this study was to assess the effects of resource and non-resource below- ground competition by grasses on fine roots of four tree species varying in their successional status. Hybrid poplar ( Populus deltoides × P. balsamifera ) and white birch ( Betula papyrifera Marsh. ) are considered early-successional or
Resource management is critical to guarantee Quality of Ser- vice when various stakeholders share the execution environ- ment, such as cloud or mobile environments. In this context, providing management techniques compatible with standard practices, such as component models, is essential. Resource management is often realized through monitoring or pro- cess isolation (using virtual machines or system containers). These techniques (i) impose varying levels of overhead de- pending on the managed resource, and (ii) are applied at different abstraction levels, such as processes, threads or ob- jects. Thus, mapping components to system-level abstrac- tions in the presence of resource management requirements can lead to sub-optimal systems. We propose Squirrel, an approach to tune component deployment and resource man- agement in order to reduce management overhead. At run- time, Squirrel uses an architectural model annotated with resource requirements to guide the mapping of components to system abstractions, providing different resource man- agement capabilities and overhead. We present an imple- mentation of Squirrel, using a Java component framework, and a set of experiments to validate its feasibility and over- head. We show that choosing the right component-to-system mappings at deployment-time reduces performance penalty and/or volatile main memory use.
Most work has focused on the embedding of VDCs in a single data center. Rabbani et al. [ 147 ] present a three-step minimum-cost-flow-based heuristic algorithm that maps VMs, switches and links separately. The algorithm first tries to assign the VDC request to a single physical server. If any of the three phases fails, the heuristic adds a new adjacent server and iterates the mapping process, while considering server defragmen- tation, residual bandwidth, communication costs and load balancing. Authors in [ 145 ] extend the study to dynamic VDCs embedding, where VM migration can be used to dynamically adjust the resource allocation plan in response to demand fluctuations and system conditions. They propose a migration-aware dynamic VDC embedding frame- work that aims to achieve high revenue while minimizing energy and migration costs. A general mathematical formulation dealing with initial VDC embedding, scaling requests and dynamic VDC consolidation is presented and solved using greedy algorithms. Xu et al. [ 146 ] consider the problem of embedding Survivable Virtual Infrastructure (graph of correlated VMs and their backups) at minimum operational costs. The optimization problem is handled in two stages (VM placement and virtual link mapping) subject to resource and bandwidth demand constraints. Authors use a heuristic to solve the VM placement sub-problem, and propose a polynomial-time linear program for mapping vir- tual links to the data-center network, while guaranteeing sufficient bandwidth for regular and failover communications between primary VMs and their backups in case of failure.
C. Resource allocation mechanisms
We will compare the social welfare (the total expected utility derived by all the users) achieved by two mecha- nisms. The first is a centralized resource allocation mech- anism where the agents divide the available resources so that the aggregate utility of all users is maximized. The second is the proportional allocation mechanisms in Kelly : each user submits a bid, interpreted as a payment, and bandwidth is allocated in proportion to the bids. We will assume quasilinear payoffs, i.e., that the payoff of a user is equal to the difference between the utility derived and the user’s bid.
I. R ESOURCES AND RESOURCE DESCRIPTIONS
Educators employ a wide variety of resources. Even in pre- internet days, educators would employ books and notes, classrooms, maps and diagrams, guest speakers, field trips, and more. In the internet era, educational resources can include all of these and more, including online resources, presentations animations, simulations, synchronous events, web quests, online mentoring, multi-user games, and more. Indeed, while some resources may be more or less pedagogically explicit, almost any resource may be used for educational purposes, and when it becomes so used, it becomes (by definition) an educational resource.
Keywords: complementarity, political economy, property rights, conflict JEL classification: H10, O10, Q34
Recent advances in the political economy of development emphasize how crucial the quality of institutions is for economic development. In particular some suggest that the economic structure and asset ownership have a decisive role in shaping institutions and development outcomes (Acemoglu and Robinson, 2008; Besley and Persson, 2009, 2010; Bourguignon and Verdier, 2009, 2010). The celebrated case of the natural resource curse exemplifies such considerations. Resource-rich developing countries seem to be unable to successfully convert their exhaustible resource into long-term growth and asset accumulation (see van der Ploeg, 2011, for a recent survey). They also display more frequent and more violent conflicts (Collier and Hoeffler, 2004; Fearon, 2005), and poorer institutions (Bates, 2007). Several mechanisms explain how extractive activities can produce relatively worse economic outcomes, but why they should encourage rent-seeking behaviors, corruption, violent conflict over rent-appropriation and discourage investment in state capacity remains an open question. This paper offers a theoretical explanation for the conflictual nature of mineral extraction, and indeed extends the discussion to any other productive endeavor.