Urban water management: optimal price and investment policy under climate variability*

Australian urban water utilities face a significant challenge in designing appropriate demand management and supply augmentation policies in the presence of significant water scarcity and climate variability. This article considers the design of optimal demand management and supply augmentation policies for urban water. In particular, scarcity pricing is considered as a potential alternative to the predominant demand management policy of water restrictions. A stochastic dynamic programming model of an urban water market is developed based on data from the ACT region. Given a specification of the demand and supply for urban water state dependent optimal price and investment policies are estimated. The results illustrate how the optimal urban water price varies inversely with the prevailing storage level and how the optimal timing of investment differs significantly between rain dependent and rain independent augmentation options.     

Modeling producer responses with dynamic programming: a case for adaptive crop management

Past research found agricultural producers’ conditional responses during the growing season are important adaptations to weather and other stochastic events. Failing to recognize these responses overstates the risks confronting producers and understates their ability to respond to adverse circumstances. Dynamic programming (DP) provides a means for determining optimal long‐term crop management plans. However, most applications in the literature base their analysis on annual time steps with fixed strategies within the year, effectively ignoring conditional responses during the year. We suggest an alternative approach that captures the strategic responses within a cropping season to random weather variables as they unfold, reflecting farmers’ ability to adapt to weather realizations. We illustrate our approach by applying it to a typical cereal farm in Karak, Jordan. The results show that including conditional within‐year responses to weather reduces the frequency of fallowing by 23% and increases expected income by 9%.     

Multiple objectives and perceptions of optimal management: The Danish industrial fishery in the North Sea

Fisheries management involves many stakeholders with differentopinions about how the fishery should be optimally managed.This paper presents a multi-objective bio-economic model, whichis able to incorporate the preferences of managers and otherstakeholders. The model is a weighted goal programme coveringthe Danish industrial fishery. Economic, political and biologicalconcerns are considered simultaneously and, by applying thepreference structures of different stakeholders, it shows howthe optimally managed fishery would look from the perspectiveof managers and various interest groups. Managers, in this casethe Danish Ministry of Food, Agriculture and Fisheries, areprovided with a management tool that shows the consequencesof their preferences towards the objectives, and can be comparedwith optimal solutions as perceived by other stakeholders.     

可持续创新系统及其动力机制分析

运用可持续发展理论、创新理论和系统工程思想,提出了可持续创新系统的基本概念和目标体系;阐述了可持续创新系统中主体的关系,进而分析了可持续创新系统的动力机制;最后对构建可持续创新系统和实现可持续发展提出了对策和建议。     

Habitat and Open Space at Risk of Land-Use Conversion: Targeting Strategies for Land Conservation

Funds available to purchase land and easements for conservation purposes are limited. This article provides a targeting strategy for protecting multiple environmental benefits that includes heterogeneity in land costs and probability of land-use conversion, by incorporating spatially explicit land-use change and hedonic price models. This strategy is compared to two alternative strategies that omit either land cost or conversion threat. Based on dynamic programming and Monte Carlo simulations with alternating periods of conservation and development, we demonstrate that the positive correlation between land costs and probability of land-use conversion affects targeting efficiency using parcel data from Sonoma County, California.     

Optimal management of a flammable forest providing timber and carbon sequestration benefits: an Australian case study*

In deciding to keep or fell a forest stand given its age, the risk of loss of timber through wildfire is an important consideration. If trees also have value from sequestration of carbon, another effect of fire is the unplanned loss of stored carbon. Factors affecting the decision to keep or fell trees, and how much to spend on fire protection, are investigated using stochastic dynamic programming, using carbon sequestration in stands of mountain ash in Victoria as a case study. The effect of treating sawlogs as a permanent carbon sink after harvesting is explored.     

山地丘陵区土壤侵蚀动态监测技术

山地丘陵地区土壤侵蚀严重,需要采取有效的措施进行土壤监测;采用“3S”集成技术,建立山地丘陵区土壤侵蚀动态监测系统;利用RS和GPS技术进行数据采集与更新,以GIS为组织手段对空间数据进行动态的分析和处理,对土壤侵蚀严重及危险区进行预警;以重庆市土壤侵蚀动态监测为例,详细介绍了土壤侵蚀动态监测系统的属性与功能。     

潭江流域森林生态资产估算及其动态变化研究

以潭江流域为例估算生态资产:(1)流域森林生态资产持续增长,但增长速度较慢;(2)按主要林种生态资产总价值排序分别为:湿地松>马尾松>阔叶林>桉树>杉树>针阔混林>相思>针混林>木麻黄>南洋楹>黎蒴,而单位面积生态价值排序为:木麻黄>相思>杉树>湿地松>针混林>阔叶树>马尾松>桉树>针阔混林>黎蒴>南洋楹与目前造林采用的以耐酸耐贫瘠的先锋林种为主有关;(3)潭江流域生态资产空间分布存在明显差异,按县级行政区排列,台山最大,依次为恩平>开平>鹤山>江门市区;(4)潭江流域单位面积生态资产为全球热带/亚热带单位面积生态资产的44.22%,说明流域现有森林结构生态效益较差,在造林过程中过应以地带性植被为主,逐渐替代目前林种.从总体来看,潭江流域以先锋林种进行造林营林不利于流域生态效益的充分发挥.     

泉州市建设用地动态变化及驱动力分析

以泉州市2001～2007年土地利用详查数据及相关统计资料为研究基础,分析了建设用地的动态变化;通过选取与建设用地密切相关的社会经济等指标,运用灰色关联度分析及软件集成等方法,分析了泉州市建设用地动态变化的驱动因素,揭示建设用地的动态变化规律。     

基于GIS的济南市城区扩展遥感动态监测

利用TM/ETM 影像,采用分类后对比法对济南市城区变化进行动态监测,在数量和空间上分析了1977~2001年济南市城区的变化;在3个时间段内,1996~2001年间城区年均增长面积最大,主要扩展方向为正东、东北、正西、西南和南部方向,但城区的整体扩展速率有所降低;通过缓冲区分析发现,济南市城区扩展趋势是以城区中心为原点,呈现同心圆式的外延扩展模式。     

Investment planning under uncertainty and flexibility: the case of a purchasable sales contract*

Investment decisions are not only characterised by irreversibility and uncertainty but also by flexibility with regard to the timing of the investment. This paper describes how stochastic simulation can be successfully integrated into a backward recursive programming approach in the context of flexible investment planning. We apply this hybrid approach to a marketing question from primary production which can be viewed as an investment problem: should grain farmers purchase sales contracts which guarantee fixed product prices over the next 10 years? The model results support the conclusion from dynamic investment theory that it is essential to take simultaneously account of uncertainty and flexibility.     

Residential housing bubbles in Hong Kong: identification and explanation based on GSADF test and dynamic probit model

We aim to investigate whether the current high housing price in Hong Kong contains a bubble and to identify the causes of such housing bubble if it exists by combining the generalised sup augmented Dickey–Fuller (GSADF) test and dynamic probit models. Empirical results indicate that the current Hong Kong housing market contains a bubble, and it’s the investors’ speculative demand and the increase of monetary supply that lead to the housing bubbles in Hong Kong. Moreover, speculative investors would prefer the mass markets to the luxury ones considering the outstanding performance of the former. Such preference would contribute to more bubbles in the mass markets than in the luxury ones. In view of these, Hong Kong Government should retrospect the linked exchange rate system and be alert to the impacts of the US monetary policies on Hong Kong residential market. To offset the housing bubble, a targeted and effective approach to the Hong Kong Government is to constrict the speculative demand from investors particularly in the mass markets.     

土地后备资源开发与耕地总量动态平衡

从我国土地资源现状出发．分析了已利用土地资源和后备土地资源状况．以及实现耕地总量动态平衡的途径．提出保持耕地总量动态平衡的一些建议。     

GIS支持下的江河源区土地覆盖遥感监测

利用1986年TM和2000年ETM卫星遥感数据,在GIS的支持下对江河源区土地覆盖变化进行了监测,14年来该区草地、林地等地表自然植被面积减少,湖泊、湿地萎缩,沙地、裸地面积扩张,荒漠化程度加剧;气候变异引起冻土退化,叠加上不合理的人类活动,是导致研究区土地覆盖变化的主要原因。     

基于“3S”的城市绿地动态监测与绿地系统规划布局研究

本研究以高分辨率遥感图像为数据源,经图像解译、信息提取等过程建立绿地信息数据库并完成绿地系统动态评估报告;在绿地系统规划方面,将以绿地系统动态评估报告为基础,将其优化、整合编制出具有科学和可行性的绿地系统规划图。     

桂西北喀斯特山区土地用地结构变化及驱动因素分析

利用土地利用变化幅度、单一土地利用动态度、综合土地利用动态度、土地利用程度综合指数等模型,对河池市土地利用动态变化分析,采用因素相关性分析法对其驱动因素进行分析;2001-2007年农业用地面积减少,园地面积逐步增长,建设用地面积一直呈现增长态势,累计增长量达5990．380hm2,2001年、2004年、2007年河池市土地利用程度综合指数分别为178．56,178．80,178．41,土地呈现从高度开发利用向合理调整转变的趋势;政策因素、经济和交通的快速发展、人口增长等都是促进土地利用变化的主要驱动因素。     

陕北能源基地水权初始分配与动态调整机制研究——以秃尾河流域为例

通过分析陕北能源重化工基地的经济发展和水资源概况,建立水权基本制度框架。针对微观层面用水单位动态变化的特征,重点探讨在初始水权分配的基础上,如何建立完善的水权动态分配机制,对用水单位的用水进行有效的监督、审查、奖惩和调整,实现水资源的高效利用,促进能源经济的发展。对秃尾河流域锦界工业园区的水权分配进行实例分析与计算。