MODELING WATER UTILIZATION IN LARGE-SCALE IRRIGATION SYSTEMS: A QUALITATiVE RESPONSE APPROACH1

ABSTRACT: Given limited available data and the present state of knowledge on the social aspects of irrigation, there is a need to develop new quantitative methods to measure water management performance in large-scale systems. A qualitative response framework is adapted to formulate a dynamic logit model of weekly field water adequacy and quantify indirectly farmer water utilization. Model parameters are estimated in a weighted least-squares regression using four seasons of data from a Philippine canal system. Estimated coefficients and independent model forecasts indicate greater effective use of rainfall than irrigation in sustaining high levels of water adequacy during the rainy season. Irrigation utilization is two times higher in the dry season, while system location has a much smaller but still significant impact. Utilization rates for both rain and irrigation showed considerable responsiveness to the prevailing scarcity of water. The qualitative response approach is well suited to the aggregated data available for large-scale systems, and allows advances in modeling dynamic water management behavior. Formal evaluation of the model will require further empirical applications.     

DROUGHT EPISODES MANAGEMENT: THE ROLE OF PRICE1

ABSTRACT: Municipal water utilities, when faced with drought conditions, typically impose a temporary water use restrictions program to achieve conservation goals. If water is sufficiently price-elastic, however, at least some of the problems associated with restrictions can be avoided by imposing a drought surcharge and allowing users to adjust voluntarily. This paper develops two sources of evidence on price elasticity in Honolulu, Hawaii, with the evidence suggesting that a drought surcharge will induce much of the desired conservation, especially when used with educational publicity.     

地价模型在农用地基准地价评估中的应用——以宿州市埇桥区为例

以埇桥区农用地为研究对象，基于农用地分等定级成果，建立不同的地价模型并进行统计检验，得到农用地综合质量和农用地价格之间的最佳关系模型，揭示农用地的综合质量和农用地价格的统计规律。研究认为，在市场交易案例很少的情况下，建立地价模型进行基准地价的评估是科学的，在此基础上对农用地基准地价进行评估和实证分析。     

基于工业代谢的工业生态链梯级循环物质流研究

以工业代谢为理论基础,运用系统分析与建模的方法对工业生态系统中的企业及其所构建的工业生态链进行理论分析与描述,揭示了工业生态系统中物质代谢及循环流动机理,并提出了简化的工业生态链的梯级循环物质流模式及其数学表达模型,对我国开展工业生态研究具有一定的参考价值和指导意义。     

水电工程抗震设防概率水准和地震作用概率模型

本文基于我国已有的二十余个重大水利水电工程场地地震危险性分析的结果,运用概率分析方法探讨了水电工程抗震设防的概率水准和地震作用的概率模型,以便为正在修订中的《水工建筑物抗震设计规范》提供依据。     

Numerical modeling of coupled variably saturated fluid flow and reactive transport with fast and slow chemical reactions

The couplings among chemical reaction rates, advective and diffusive transport in fractured media or soils, and changes in hydraulic properties due to precipitation and dissolution within fractures and in rock matrix are important for both nuclear waste disposal and remediation of contaminated sites. This paper describes the development and application of LEHGC2.0, a mechanistically based numerical model for simulation of coupled fluid flow and reactive chemical transport, including both fast and slow reactions in variably saturated media. Theoretical bases and numerical implementations are summarized, and two example problems are demonstrated. The first example deals with the effect of precipitation/dissolution on fluid flow and matrix diffusion in a two-dimensional fractured media. Because of the precipitation and decreased diffusion of solute from the fracture into the matrix, retardation in the fractured medium is not as large as the case wherein interactions between chemical reactions and transport are not considered. The second example focuses on a complicated but realistic advective-dispersive-reactive transport problem. This example exemplifies the need for innovative numerical algorithms to solve problems involving stiff geochemical reactions.     

MONTHLY RUNOFF PREDICTIONS BASED ON RAINFALL FORECASTS IN A SMALL OKLAHOMA WATERSHED1

ABSTRACT: Conditions under which monthly rainfall forecasts translate into monthly runoff predictions that could support water resources planning and management activities were investigated on a small watershed in central Oklahoma. Runoff response to rainfall forecasts was simulated using the hydrologic model SWAT. Eighteen scenarios were examined that represented combinations of wet, average, and dry antecedent rainfall conditions, with wet, normal, and dry forecasted rainfall. Results suggest that for the climatic and physiographic conditions under consideration, rainfall forecasts could offer potential application opportunities in surface water resources but only under certain conditions. Pronounced wet and dry antecedent rainfall conditions were shown to have greater impact on runoff than forecasts, particularly in the first month of a forecast period. Large forecast impacts on runoff occurred under wet antecedent conditions, when the fraction of forecasted rainfall contributing to runoff was greatest. Under dry antecedent conditions, most of the forecasted rainfall was absorbed in the soil profile, with little immediate runoff response. Persistent three‐month forecasts produced stronger impacts on runoff than one‐month forecasts due to cumulative effects in the hydrologic system. Runoff response to antecedent conditions and forecasts suggest a highly asymmetric utility function for rainfall forecasts, with greatest decision‐support potential for persistent wet forecasts under wet antecedent conditions when the forecast signal is least dampened by soil‐storage effects. Under average and dry antecedent conditions, rainfall forecasts showed little potential value for practical applications in surface water resources assessments.     

Time allocation strategies in insect parasitoids: from ultimate predictions to proximate behavioral mechanisms

As most parasitoids are time limited, they usually die before they have laid all their eggs. In such cases, optimal foraging theory predicts that female parasitoids will adopt behavioral reproductive strategies enabling them to maximize progeny production per unit of time. One key situation in which parasitoid females must optimize their time budget is related to the fact that most of their hosts are distributed in discrete patches in the environment. In this review, I first present the results of basic theoretical models predicting female wasp search duration on a patch of hosts. I then compile and analyze all studies investigating the effect of different factors on parasitoid patch time allocation and patch-leaving decision rules. Different patch-leaving mechanisms that were proposed to explain the results obtained are discussed, along with statistical methods that should be used to estimate them from experimental data. Finally, ideas for future research are presented.     

多收入阶层CGE模型在能源资源税改革效应分析中的应用研究

开展能源资源税改革效应分析,是评估环境政策改革在环境效益、经济效率和公平效应上是否实现共赢目标的基础工作.通过细分社会核算矩阵中的居民收入组账户,构建面向多收入阶层的CGE模型,有利于量化环境税费领域改革产生的效应.经模拟测算得到,中国能源资源税改革将对GDP、部门总产出和社会总消费等主要宏观经济指标带来负面影响,但均在可接受范围内.微观层面上,居民收入组内的可支配收入和消费支出则受到不同程度的负面影响.     

中国生态效率的空间格局与影响机制分析

实现经济增长的生态友好模式转变是当代中国建设两型社会的必然要求,而中国地区生态效率的空间格局及影响因素分析是地理学研究的重要问题.基于此,本文利用随机前沿模型测算2004—2012年间我国地区生态效率,其次,基于探索性空间分析技术对生态效率的空间关联特征进行分析,最后,借助空间计量经济模型对区域生态效率的影响因素进行分析.结果表明:中国地区生态效率总体呈上升趋势,但效率水平偏低,东部地区生态效率高于中西部地区;生态效率空间分异格局显著,且具有正向的空间相关性,其中,低-低生态效率区域集聚分布于我国西部内陆,高-高生态效率集聚区分布于东南沿海;空间面板回归显示,城市化水平及经济发展的提高有助于区域生态效率的提高,环境法规的实施及有效的环境监管可以确保生态安全,而第二、三产业比重的增加不利于生态效率的提高.