Ordering the extraction of renewable resources: The case of multiple aquifers

Optimal sequencing of resource extraction is typically studied for nonrenewable resources. We provide conditions for optimal use of multiple sources of a renewable resource and characterize the resulting extraction sequence, resource scarcity values, and (single) efficiency price path for two groundwater aquifers and an abundant alternative resource. Even with one demand, the optimal sequence depends on the differential opportunity costs of the two renewables. A numerical simulation for the South O‘ahu aquifer system, which also allows for different distribution costs, illustrates the case of using the “leakier” aquifer first and then switching to simultaneous use of both resources. The welfare gain from specialization relative to independent management is $4.7 billion.     

Cooperative Management of Groundwater Resources in the Presence of Environmental Externalities

This paper investigates how cooperation among users can achieve a better management of groundwater in the presence of environmental externalities. Cooperation allows users to internalize the damages caused by their activities and reduce extractions. The paper develops a game theoretical framework to assess the value of cooperation in an aquifer that is divided into three sub-aquifers that are being overly exploited. Two types of externalities are modeled: first, water extractions in each sub-aquifer impact water levels in neighboring sub-aquifers (extraction externality). Second, the three sub-aquifers are also connected to an ecosystem and thus decisions in each sub-aquifer affect the health of the ecosystem (environmental externality). A cooperative game theory model is applied. The model empirically shows how the uncontrolled extractions in each sub-aquifer affects neighboring groundwater users but also cause severe impacts to the linked ecosystem. The model is tested empirically in one of the most important aquifers in Spain, the Eastern la Mancha aquifer. The results illustrate how both extraction and environmental externalities interact in affecting the likelihood of cooperation among the users. The paper estimates the value of cooperation and its stability with and without the environmental externality.     

Sushi or Fish Fingers? Seafood Diversity,Collapsing Fish Stocks,and Multispecies Fishery Management*

We present a model of a multispecies fishery, and we show the following. (i) Consumer preferences for seafood diversity can trigger a sequential collapse of fish stocks under open‐access fishery. (ii) The stronger the preferences are for diversity, the higher is the need for coordinated multispecies regulation. (iii) Second‐best optimal management of only one (or a few) species is less strict than socially optimal management of the same species. (iv) Myopic regulation of one species, ignoring spillovers to other species, can cause depletion of other stocks that would not be depleted under open access.     

Groundwater and ecosystems damages: Questioning the Gisser-Sánchez effect

Gisser and Sánchez (1980a) state the conditions under which welfare gains from policy intervention are negligible in aquifer management, when compared with non-regulation or “free market” outcomes. This is the so-called Gisser-Sánchez effect (GSE), which has been supported by the ensuing literature during recent decades. The GSE requires a number of assumptions, among which is the disregard for aquatic ecosystems linked and dependent on aquifer systems. The depletion of aquifer systems in arid and semiarid regions worldwide is causing acute water scarcity and quality degradation, and leading to extensive ecosystem damages. This study shows that by including environmental damages into the analytical model, results can change substantially. The analysis highlights both theoretically and empirically the importance of policies in groundwater management, as well as the potential role for stakeholders' cooperation. The empirical application deals with two large aquifers in Spain, the Western La Mancha aquifer which is grossly mismanaged, and the Eastern La Mancha aquifer, which is moving towards sustainable management. Western and Eastern La Mancha aquifers illustrate that policies and institutions are essential to avoid the current global aquifer mismanagement.     

Mountain-to-sea ecological-resource management: Forested watersheds,coastal aquifers,and groundwater dependent ecosystems

Improving the understanding of connections spanning from mountain to sea and integrating those connections into decision models have been increasingly recognized as key to effective coastal resource management. In this paper, we aim to improve our understanding of the relative importance of linkages between a forested watershed, a coastal groundwater aquifer, and a nearshore marine groundwater-dependent ecosystem (GDE) using a dynamic groundwater optimization framework and simple ecosystem equations. Data from the Kīholo aquifer on the Kona Coast of Hawai‘i Island are used to numerically illustrate optimal joint management strategies and test the sensitivity of those strategies to variations in physical and behavioral parameter values. We find that for a plausible range of watershed management costs, protecting part of the recharge capture area is always optimal. Without watershed protection, maintaining a safe minimum standard growth rate for a GDE-dependent marine indicator species, reduces net present value non-trivially, but optimal investment in watershed conservation offsets that potential reduction by 75 %. In general, we find that optimal watershed management and groundwater pumping are most sensitive to changes in water demand growth and parameters that describe nearshore salinity.     

Groundwater balance and conservation under different water pricing and agricultural policy scenarios: A case study of the Hamadan-Bahar plain

Government subsidies for agricultural activities in recent decades have encouraged farmers of Hamadan-Bahar plain to extend the number of wells and irrigated farms, with no consideration of groundwater resource conservation. As a result, the level of the groundwater table has decreased continuously in this area, threatening the life of groundwater aquifer. The objective of the study is to analyze the impacts of irrigation water pricing and agricultural policy scenarios on aquifer conservation by considering the dynamic relations between aquifer groundwater balance and the agriculture sector. For this purpose a combination of simulation and optimization techniques is considered in a dynamic framework. Firstly, dynamic treatments of groundwater and the main factors affecting the balance of studied aquifer are simulated. Then, optimization behaviour of agriculture sector related to farmers' decision-making processes is defined on the time horizon. Thereafter all of the equations are used simultaneously by a non-linear dynamic programming method, which maximize present value of gross margins of agriculture sector subject to groundwater constrains and other input limitations. The analysis of the results indicates that water pricing by itself can considerably reduce the agricultural demand for aquifer groundwater in the Hamadan-Bahar plain.     

Renewable resource management with stock externalities: Coastal aquifers and submarine groundwater discharge

We model coastal groundwater management and its effects on submarine groundwater discharge, nearshore marine water quality, and marine biota. Incorporating the stock externality effects on nearshore resources increases the optimal sustainable steady-state levels of both the aquifer head and the stock of a keystone native algae species. Numerical simulations are illustrated using data from the Kuki’o region on the Island of Hawaii. Two different approaches for incorporating the nearshore resource are examined. Including algae's market value in the objective function results in only slightly lower rates of groundwater extraction. When a minimum constraint is placed on the stock of the keystone species, however, greater conservation may be indicated. The constraint also results in non-monotonic paths of water extraction, head level, and marginal opportunity cost of water in the optimal solution.     

On the spatial nature of the groundwater pumping externality

Most existing economic analyses of optimal groundwater management use single-cell aquifer models, which assume that an aquifer responds uniformly and instantly to groundwater pumping. In this paper, we develop an economic model of groundwater management that explicitly incorporates spatial dynamic groundwater flow equations. Calibration of our model to published economic studies of specific aquifers demonstrates that existing studies generally incorrectly estimate the magnitude of the groundwater pumping externality relative to spatially explicit models. In particular, for large aquifers with surface areas of thousands of square miles, the marginal pumping externality predicted by single-cell models may be orders of magnitude less than that predicted by a spatially explicit model, even at large distances from a pumping well. Conversely, for small aquifers with areas of a few hundred square miles or less, single-cell models reasonably approximate the pumping externality. Application of single-cell models to inappropriate settings may result in misleading policy implications due to understatement of the magnitude and spatial nature of the groundwater externality.     

On the inconsistent behavior in voting for incumbents and for term limitation

This paper considers the seemingly inconsistent behavior of individuals who simultaneously vote for incumbents and for limitations on their terms in office. We argue that such behavior may occur even if voters pursue their self-interests in both candidate and term-limitation elections. First, we formulate elections for Congressional candidates as a two-person game, where each candidate maximizes votes by proposing a distribution of benefits to voters. Then we discuss the term limitation at the state level, where voters in each district compare, over time, the average benefits obtained from two alternative series of campaign games: one with a longer tenure associated with no term limit and the other with a shorter tenure created by the introduction of a term limit. In elections of candidates for Congress, the incumbent is successful because he can generate more aggregate benefits for voters. We show, however, that at some critical point of the tenure, his behavior will be less beneficial to his core constituents. In term-limitation elections, those voters tend to support a term limit. In some cases, they represent a majority in the state, and term limits are enacted. Received: February 23, 1999; revised version: January 24, 2000     

DYNAMIC CONTRACTS WITH WORKER MOBILITY VIA DIRECTED ON‐THE‐JOB SEARCH

This article proposes a model with dynamic incentive contracts and on‐the‐job search in a frictional labor market. The optimal long‐term contract exhibits an increasing wage–tenure profile. With increasing wages, worker effort also increases with tenure. These two features imply that the probabilities of both voluntary and involuntary job separation decrease with both job tenure and the duration of employment. Given these results, workers experience differing labor market transitions—between employment, unemployment, and across different employers—and the equilibrium generates endogenous heterogeneity among ex ante homogeneous workers.     

Groundwater management: The effect of water flows on welfare gains

We construct a spatially explicit groundwater model that has multiple cells and finite hydraulic conductivity to estimate the gains from groundwater management and the factors driving those gains. We calibrate an 246-cell model to the parameters and geography of Kern County, California, and find that the welfare gain from management for the entire aquifer is significantly higher in the multi-cell model (27%) than in the bathtub model (13%) and that individual farmer gains can vary from 7% to 39% depending of their location and relative size of demand for water. We also find that when all farmers in the aquifer simultaneously behave strategically the aggregate gains from management are significantly smaller. However, individual farmers do not have the incentive to behave strategically even with finite hydraulic conductivity when other farmers behave myopically.     

A waste management model for optimal recycling-landfilling policies under macroeconomic conditions

This research provides a waste management model in the presence of macroeconomic conditions. An optimal control problem which integrates the recycling-landfilling decision with industry supply-demand dynamics is designed to achieve the value-maximizing objective. The model simultaneously considers idiosyncratic technical and aggregate demand shocks, while the stoppage time for landfill use is assumed to follow a Cox process with the intensity function of a firm's total waste collection. The closed-form solution of the optimal recycling ratio is also derived. The results suggest that when macroeconomic effects are neglected, optimal recycling ratios tend to be underestimated.     

Mitigating Negative Water Quality and Quality Externalities by Joint Management of Adjacent Aquifiers

Groundwater basins are usually separated into aquifers that are hydrologically interrelated. This interrelation may take the form of water movement from one aquifer to another. When differentials in water quality exist, pumping from one of the aquifers can cause water movement that may be associated with degradation of its quality. A management policy that considers this interrelation may be preferable to an independent management of each aquifer. This paper develops a dynamic optimal control model to evaluate joint versus independent management. The optimal joint pumping management, in which two adjacent aquifers of different water qualities are interrelated, is analyzed and compared to independent aquifer pumping, and the situations where joint management is not required are identified. Policy implications are then derived and discussed. Finally, the theoretical model is applied to a case of interrelated aquifers in southern Israel. The empirical model identifies conditions (interest rate, agricultural fresh water supply rainfall recharge, price of surface water, drinking water quality standards) under which a joint policy is preferable. The empirical results confirm the theoretical ones.     

Privatization of Water-Resource Development

This paper analyzes the inefficiencies from market power and return-flow externalities in private construction of a water project. The model pays special attention to increasing groundwater pumping costs, project set-up costs, limited project capacity, and return flow to the aquifer. For a given capacity, the return-flow externality causes project owners to construct the project too late when the price of groundwater is too high because the external benefit of return-flow to the aquifer is not captured. Market power exacerbates these effects since the project owner delays construction to accelerate groundwater overdraft. The return-flow externality and market power also decrease installed capacity and increase overdraft from the aquifer. Applying the model to the construction of the Central Arizona Project (CAP) for a given capacity, the estimated deadweight loss from hypothetical private construction of the project ($0.853 billion) is substantially less than the literature’s estimate of deadweight loss from actual construction by the Bureau of Reclamation ($2.603 billion). However, under the federal subsidies and insecure property rights that accompanied the CAP, private construction results in a larger estimated efficiency loss ($6.126 billion).     

Strategic entry and externalities in groundwater resources: Evidence from the lab

This study uses economics experiments to extend the literature on common-pool resources by focusing on entry investment behavior in a stylized, spatially explicit aquifer. The model consists of a two-stage game, where participants make an entry decision in the first stage and, if they choose to enter, decide how much resource to extract in the second stage. Results show that entry behavior and groundwater pumping decisions are significantly affected by the underlying spatial externalities of the resource. In instances where the impacts of groundwater use are spread across all resource users, we observe both a greater number of users choosing to use the resource and a higher intensity of use. The results support expectations from the model that groundwater management policies should focus on entry in addition to decisions related to the volume of pumping. The results also discern the interplay of entry with both hydrogeologic characteristics of the resource and the option to exit and reveal that the option to exit increases the intensity of extraction as well as initial entry rates.     

JOB REALLOCATION, EMPLOYMENT CHANGE AND AVERAGE JOB TENURE: THEORY AND WORKPLACE EVIDENCE FROM AUSTRALIA

We explore determinants of job reallocation, employment change and average job tenure in this paper. A model which associates technological advances with the process of economic growth is modified and analysed. The features of this model allow for the possibility of asymmetric behaviour when looking at the net change in employment. Workplace data from Australia (AWIRS95) are used to test the predictions generated from the model for both employment change and average job tenure. Results are presented that provide clear evidence as to the nature of workplaces in which net employment growth is concentrated. We find that employment growth is asymmetrically related to expected changes in demand for the output of the workplace. We also find that employment is lower for workplaces that are larger, older, have greater union density, offer higher relative earnings, or are operating in a more competitive environment. The impacts on average tenure are as expected from the model and from these changes in employment. Overall there is a substantial degree of agreement between the predictions of the model and our empirical results.     

CONTROL ALLOCATION,REVENUE SHARING,AND JOINT OWNERSHIP*

This article develops a two‐period double moral hazard model with incomplete contracting to explore the implication of a possible adverse effect of unilateral control on the optimal revenue sharing and control allocation in a joint venture. We identify conditions under which joint ownership and control become optimal when unilateral control gives the controlling party opportunities to inefficiently extract private benefits at the expense of the joint revenue. Moreover, this adverse consequence of control may also lead to the separation of share ownership and control, i.e., it may be optimal for the minority owner to have the control rights.     

Depletion,climate, and the incremental value of groundwater

Groundwater provides vital inputs to crop production and contributes to rural economies throughout the world. Research on the economic benefits associated with groundwater resources has typically focused on the impacts of groundwater availability on the profitability of agricultural production or on the non-market benefits associated with groundwater quality for human consumption. In this research, we use stated-preference methods to investigate the total economic value to agricultural producers of an increase in groundwater availability in the Ogallala Aquifer region. The contingent valuation method allows for estimation of values beyond agricultural profitability, including non-market values such as the ability to leave additional groundwater to future generations. We find a median willingness to pay (WTP) for an additional 100 gallons per minute of well capacity of $77 per well, and that this estimate depends strongly on current well capacity and climate conditions. For counties in hotter and drier regions of the aquifer with low well capacity, median WTP is significantly higher. These results are then used in conjunction with projections of future climate and groundwater availability to generate predicted changes in the WTP for additional groundwater across the aquifer. This research provides important feedback on how the benefits of additional groundwater availability are predicted to change as groundwater resources are diminished in a changing climate.     

Forest management under fire risk when forest carbon sequestration has value

We develop a multiple forest use model to determine the optimal harvest date for a forest stand producing both timber and carbon benefits under a risk of fire. An empirical application is provided for a forest owner producing maritime pine in Southwest of France. Our results indicate that a higher risk of fire will decrease the optimal rotation period. On the contrary, higher carbon prices increase the optimal harvesting age. To investigate the contradictory effects of fire risk and carbon price on forest rotation, we identify the set of carbon prices and fire risks that lead to a given rotation age. We also show that forest owner's willingness to pay for a risk reduction can be substantial (37.33 euros by ha and by year to reduce the annual fire risk from 1.26% to 0.07%).