1、Chapter 9 Replenishable But Depletable Resources: Water 9.1 Introduction Main contents: Examining the likelihood and severity of water scarcity Defining the efficient allocation of ground and surface water over time and comparing these allocation to current practice Examining the menu of opportuniti
2、es for meaningful institutional reform 9.2 The Potential For Water Scarcity Two rather different sources of available water supplies: Surface water which consists of the fresh water in rivers, lakes, and reservoirs that collects and flows on the earths surface. Groundwater which collects in porous l
3、ayers of underground rock known as acquifers. 9.2 The Potential For Water Scarcity To water scarcity, quantity of water is not the only problem. Quality is also a problem. 9.3 The Efficient Allocation of Scarce Water What efficiency means for the allocation of water depends crucially on whether surf
4、ace water or groundwater is being tapped. In the absence of storage, the problem with surface water is to allocate a renewable supply among competing users. Intergenerational effects are less important as future supplies depend on natural phenomena (such as precipitation) rather than on current with
5、draw practices. For groundwater, on the other hand, withdrawing water now does affect the resources available to future generations. In this case, the allocation over time is a crucial aspect of the analysis. 9.3 The Efficient Allocation of Scarce Water An efficient allocation of surface water: Must
6、 strike a balance among a host of competing users Must supply an acceptable means of handling the year-to-year variability in surface water flow. 9.3 The Efficient Allocation of Scarce Water How to strike a balance among a host of competing users? The water should be allocated so that the marginal n
7、et benefit is equlized for all uses. Figure 10.2 9.3 The Efficient Allocation of Scarce Water How to deal with fluctuations in supply? As long as the supply level can be anticipated, the equal marginal net benefit rule still applies, but different supply levels may imply very different allocations a
8、mong users. This is an important attribute of the problem because it implies that simple allocation rules, such as each user receiving a proportion of the available flow or high-priority users receiving a guaranteed amount, are not likely to be efficient. 9.3 The Efficient Allocation of Scarce Water
9、 Analyzing the efficient allocation of groundwater, the depletable nature of groundwater supplies be explicitly taken into account. 9.3 The Efficient Allocation of Scarce Water The efficient allocation of groundwater over time. The efficient allocation should consider the marginal user cost. The eff
10、icient extraction path for constant demand involves declining use of groundwater over time. The marginal extraction cost would rise over time as the water table fell. Pumping would stop either when The water table ran dry The marginal cost of pumping was either greater than the marginal benefit of t
11、he water or greater than the marginal cost of acquiring water from some other source. 9.3 The Efficient Allocation of Scarce Water The efficient allocation of groundwater over time. Abundant surface water in proximity to the location of the groundwater could serve as a substitute for groundwater, ef
12、fectively setting an upper bound on the marginal cost of extraction. In efficient groundwater markets, the water price would rise over time. 9.4 The Current Allocation System Allocation system and its efficiency 我国水资源的分配体系及其有效性分析： 我国水资源的分配体系： 通过对取水许可的管理来实施 目前尚无明确的分配标准，主要是根据取水户提 出的取水计划及各级水行政主管部门制定的用水
13、 计划来核定、审批。 各级水行政主管部门在分配其取水许可量时按 “优先顺序”分配， 即首先满足城乡居民生活用 水， 统筹兼顾农业、工业用水和航运需求，并维 持生态环境用水。各级水行政主管部门根据取水 户的实际取水量征收水资源费，实行有偿使用。 我国水资源的分配体系及其有效性分析： 我国水资源分配的有效性分析： 分配标准不明确，不能保证水量分配的公平性， 也不能有效控制节约用水。 水资源分配的优先顺序不能保证用水的公平与 效率。 有偿使用制度执行不彻底。 9.4 The Current Allocation System Sources of inefficiency: Restrictions
14、 on transfers Water pricing Common property problems 9.4 The Current Allocation System Restrictions on transfers With a well-structured system of water property rights, efficiency can be a direct result of the transferability of the rights. Users receiving low marginal net benefits from their curren
15、t allocation would trade their rights to those who would receive higher net benefits. Both parties would be better off. 9.4 The Current Allocation System Water pricing Both the level of prices and the rate structure are at fault In general, the price level is too low The rate structure does not adeq
16、uately reflect the costs of providing service to different types of customers. 9.4 The Current Allocation System Water pricing For surface water the rates are too low for two reasons: Historic average costs are used to determine rates Marginal scarcity rent is rarely included. Efficient pricing requ
17、ires the use of marginal, not average, cost, including marginal user cost. 9.4 The Current Allocation System Common property problems The allocation of groundwater must confront one additional problem. When many users tap the same aquifer, that aquifer becomes a common property resource. Tapping a c
18、ommon property resource will tend to deplete it too rapidly, users lose the incentive to conserve. The marginal scarcity rent will be ignored. 9.4 The Current Allocation System Common property problems For common property resources, economic theory suggests several direct consequences. Pumping costs
19、 would rise too rapidly Initial prices would be too low Too much water would be consumed by the earliest users. 9.5 Potential Remedies The first reform would reduce the number of restrictions on water transfers. Allowing users to capture the value of water saved by permitting them to sell it would s
20、timulate water conservation and allow the water to flow to higher valued uses. 9.5 Potential Remedies Getting the prices right is another avenue for reform A marginal cost pricing system should be used to determine the price of water. Government intervention Discussion questions: What pricing system
21、 identified in Table 10.1 best describes the pricing system used to price the water you use at your college or university? Does this pricing system affect your behavior about water use(length of showers, etc.)? How ? Could you recommend a better pricing system in this circumstance? What would it be? Objectives & Requirements: Understand the potential for water scarcity Grasp the efficient allocation of scarce water Know the current allocation system and find the potential remedies
