A dynamic water accounting framework based on marginal resource opportunity cost

Abstract

Abstract. Many river basins throughout the world are increasingly under pressure as water demands keep rising due to population growth, industrialization, urbanization and rising living standards. In the past, the typical answer to meet those demands focused on the supply-side and involved the construction of hydraulic infrastructures to capture more water from surface water bodies and from aquifers. As river basins were being more and more developed, downstream water users and ecosystems have become increasingly dependent on the management actions taken by upstream users. The increased interconnectedness between water users, aquatic ecosystems and the built environment is further compounded by climate change and its impact on the water cycle. Those pressures mean that it has become increasingly important to measure and account for changes in water fluxes and their corresponding economic value as they progress throughout the river system. Such basin water accounting should provide policy makers with important information regarding the relative contribution of each water user, infrastructure and management decision to the overall economic value of the river basin. This paper presents a dynamic water accounting approach whereby the entire river basin is considered as a value chain with multiple services including production and storage. Water users and reservoirs operators are considered as economic agents who can exchange water with their hydraulic neighbours at a price corresponding to the marginal value of water. Effective water accounting is made possible by keeping track of all water fluxes and their corresponding hypothetical transactions using the results of a hydro-economic model. The proposed approach is illustrated with the Eastern Nile River basin in Africa.

The use of AQUATOOL DSS applied to the System of Environmental-Economic Accounting for Water (SEEAW)

“…To this end, water accounts are presented as a tool to achieve the objective of water efficiency. One of the targets of water accounting is, in addition to comparing results between different territories, to measure the contribution of each water user to the overall economic value of water resources in order to identify real potential water savings (Ward and Pulido-Velázquez, 2008;Dumont et al, 2013;Tilmant et al, 2015).…”

“…As observed, building water accounts is a complex task, mainly due to the lack of common European definitions and procedures and the difficulty of the collection of the required data. As noted by Tilmant et al (2015), although the SEEAW is increasingly adopted, there is no unified procedure to establish water accounts, nor there is an agreement on how water accounts must be presented. Dimova et al (2014) also indicate that although the SEEAW concepts are relatively simple, its implementation requires collecting a variety of data from numerous actors and stakeholders.…”

Beyond “More Crop per Drop”: evolving thinking on agricultural water productivity

“…For instance, the United States Geological Survey (USGS) discontinued calculations to estimate return flows and consumptive water use due to resource and data constraints in 1995; since then, USGS has relied on estimates of water withdrawals rather than water depletions as the basis for its semi-decadal report on water use (Maupin et al 2014). Continued development of water accounting and remote sensing tools (e.g., United Nations 2012; Karimi et al 2013a;Tilmant et al 2015) is needed to lessen the constraints of data limitations, and enhance the ease and precision with which water productivity estimates can be made at multiple scales.…”

中国主要城市水资源价值评价与定价研究

“…。 尽管中国城市供水价格历经 20 多年演变， 已经 由社会福利型的 "水费" 转变为反映市场供需和资 源稀缺性的 "水价" [4] [3] 以及李春 雨等 [6] 作了较为系统的梳理， 大致可将水资源定价 方法分为三类， 分别是基于市场机制、 基于资源优 化配置和基于综合指标的水价确定模型。 第一类水价确定模型是基于市场机制将水资 源视作普通商品， 借助市场均衡条件来确定水价。 例如， 供求定价模型是借助用水需求的价格弹性系 数， 模拟水价变动对用水需求的影响， 进而根据用 水需求的控制目标来确定相应水价 [7] 。 第二类水价确定模型是通过构建水资源配置 优化模型： 在水资源总量既定的约束下， 从多种用途 中选取经济净收益最大的配置方案。将最优配置 方案对应的水资源影子价格作为水价。其实际上反 映的是水资源的边际机会成本， 即水资源可以创造 的最大的经济价值 [8,9] 互交织。为此， 对水资源价值的评价要从 "量" 和 "质" 两方面反映。其中， 对水资源 "量" 的评价更侧 重其相对于用水需求的相对稀缺性。钦丽娟等 [11] 和 简富缋等 [12] 均利用模糊数学综合指标评价法， 分别 对郑州和黑河中游的水资源价值进行了评价。 3 研究方法与数据基础 通过比较已有水资源价格理论和方法， 本文选 取基于综合指标的水资源价格确定模型， 以便客观地 对不同城市水资源价值进行统一评价与横向对比。 3.1 评价指标选取 参考姜文来 [10] 、 钦丽娟等 [11] 和简富缋等 [12] [11] 和简富缋等 [12] 以主要污染物(如 COD、 氨氮等) 浓度作为评价指标， 但其数据难以获 取且不同监测点差异较大， 难以有效反映整个区域 的水质情况。因此， 本研究分别根据地表水评价标 准(GB 3838-2002) [13] 和 地 下 水 评 价 标 准(GB/T 14848-93) [14] Table 1 Index system for the evaluation of water resources [13] ， 对应不同水质分类的河流长度 参考 GB 3838-2002 [13] ， 对应不同水质分类的湖库面积 参考 GB/T 14848-93 [14] 1) 总用水可分为生产用水、 生活用水和生态用水。其中生态用水指回补生态环境的用水， 用水比例较小， 因此一般主要考虑生产用水和…”