A SATURATION-BASED MODEL OF RELATIVE WETNESS FOR WETLAND IDENTIFICATION1

ABSTRACT: A wetness index that was derived from Beven's distributed hillslope runoff model and based on the concept of relative wetness is introduced as a wetland identification and mapping tool. Data requirements are modified to make the model suitable for use by managers and field agents. The model predicts the relative propensity of any point or small area within a landscape unit to become saturated. This allows an index of relative wetness to be produced. Points on the landscape can then be assigned values of relative wetness. The index has potential utility for: (1) providing more detailed information on wetness conditions than binary (wetland-nonwetland) classification systems now in use; (2) assisting in wetland identification when field indicators are absent or ambiguous; (3) application in dryland environments where common wetland indicators are largely irrelevant; and (4) broad-scale wetland mapping in a geographic information systems environment using existing digital topographic and soils databases.     

规划管制下土地发展权受限的多情景测度:数量与价值

在统筹推进国土空间规划及用途管制的背景下,揭示土地发展权受限的数量及其价值,对于完善中国空间治理体系、解决不平衡不充分发展尤其是区域差异问题具有重要的理论和现实意义。文章以湖北省为"生态资源优势区"代表性省份,首先运用柯布-道格拉斯(C-D)生产函数模型测算各生产要素在农业与非农业部门中对经济增长的弹性以及土地资源在两部门的边际收益,揭示土地发展权受限的客观现实和成因;然后基于缩小湖北省与"经济发展优势区"经济发展差距的不同情景,测度2009—2018年湖北因处于生态资源优势区而使土地发展权受限的数量与价值。结果显示:(1)土地要素投入对湖北省经济增长具有重要影响。2009—2018年,湖北省非农部门经济增长仍依赖土地要素投入,且土地要素对经济增长的贡献难以被其他生产要素替代。(2)高额的机会成本是土地资源由农业部门向非农部门转移的重要潜在驱动力。2009—2018年,湖北省非农部门的土地边际收益是农业部门的17.03~44.14倍,且呈逐年递增趋势,规划管制的存在导致了土地发展权受限。(3)规划管制背景下,对受限的土地发展权进行补偿具有必要性和可行性。在经济发展水平差距缩小10%~100%的不同情景下,2009—2018年湖北省土地发展权受限数量处于0.53×104~5.35×104hm2之间,对应的价值量占同时期"经济发展优势区"总GDP的比重较低,为0.02%~0.19%。基于此,应开展土地发展权受限补偿的制度建设,从土地发展权产权确认和利益分配机制改革两方面量化和落实土地发展权,并以对土地发展权的底线补偿情景为起点逐步提高土地发展权补偿水平,直至实现完全补偿。     

Understanding the Large‐Scale Influence of Levees on Floodplain Connectivity Using a Hydrogeomorphic Approach

The widespread construction of levees has reduced river–floodplain connectivity and altered associated fluvial processes in many river systems. Despite the recognition that levees can alter floodplain connectivity, few studies have examined the role of levees in reducing floodplain areas at large watershed scales. This paper explores the application of a hydrogeomorphic floodplain inundation model in the Wabash Basin, located in the Midwestern United States, to assess changes in floodplain area in levee‐protected areas. We evaluate 10‐ and 30‐m topographic resolutions and spatially examine the influence of levees on floodplain area in relation to river network attributes. Generally, floodplains in levee‐protected areas were influenced by topographic resolution, stream order, and elevation details of levees found in topography datasets. We show, when compared to Federal Emergency Management Agency maps, our approach underpredicts floodplain area when using 10‐m resolution topography data but only slightly overpredicts when using 30‐m resolution data. After removing details of levees from topography data, we found changes in floodplain area varied spatially, but basin‐aggregate results changed little compared to topography datasets that contain levees, though larger floodplain areas were produced in some regions where levees were removed. This work contributes to a growing research emphasis on using hydrogeomorphic floodplain models to understand floodplain disconnectivity.     

Managing uncertainties through scenario analysis in strategic environmental assessment

Planning for the future is uncertain, and scenario analysis is a method of coping with the uncertainties of future plans. This paper addresses how to deal with future uncertainties by using scenario analysis as a possible approach for conducting a strategic environmental assessment (SEA). Although scenario-based approaches have been linked to strategic planning and SEA, this paper for the first time proposes how a combined approach may be implemented using specific tools and methodologies and, further on, it also implements the first three stages of the six stages proposed for the ‘scenario-based strategic planning’ approach. This work is an attempt to standardize SEA and scenario analysis as a combined approach. The three stages are tested within the Tourism Development Plan of the Iranian province of Gilan, which has been selected as a case study.     

Developing alternative land-use scenarios to facilitate natural resource management across jurisdictional boundaries

Scenario planning is an effective approach for examining possible futures by exploring the implications and consequences of different policy responses to landscape stressors. We present here a case study that explores plausible futures of urban growth in Southern Nevada, USA that illustrates how scenario analysis can be used to inform region-wide resource management by spatially modeling drivers of change, resource impacts, and potential policy responses. Using a suite of energy, water and biodiversity impact models, we assess the outcomes of the various futures on priority resources, resulting in a clear basis of comparison between alternative policies and their potential outcomes. This case study demonstrates the utility of scenario modeling for natural resource management by exploring crucial policy decisions that might be made in the near-term that could have lasting and sometimes conflicting influences on regional resources over the long term.     

A Scenario Optimization Model for Dynamic Reserve Site Selection

Conservation planners are called upon to make choices and trade-offs about the preservation of natural areas for the protection of species in the face of development pressures. We addressed the problem of selecting sites for protection over time with the objective of maximizing species representation, with uncertainty about future site development, and with periodic constraints on the number of sites that can be selected. We developed a 0–1, linear optimization model with 2 periods to select the sites that maximize expected species coverage subject to budget constraints. The model is based on the idea that development uncertainty can be characterized by a set of scenarios, each of which is a possible second-period development outcome for the set of sites. We also suggest that our 2-period model can be used in a sequential fashion that is consistent with adaptive planning. Results are presented for the Fox River watershed in Chicago.     

Future Greenhouse Gas and Local Pollutant Emissions for India: Policy Links and Disjoints

This paper estimates the future greenhousegas (GHG) and local pollutant emissions forIndia under various scenarios. Thereference scenario assumes continuation ofthe current official policies of the Indiangovernment and forecasts of macro-economic,demographic and energy sector indicators.Other scenarios analyzed are the economicgrowth scenarios (high and low), carbonmitigation scenario, sulfur mitigationscenario and frozen (development) scenario.The main insight is that GHG and localpollutant emissions from India, althoughconnected, do not move in synchronizationin future and have a disjoint under variousscenarios. GHG emissions continue to risewhile local pollutant emissions decreaseafter some years. GHG emission mitigationtherefore would have to be pursued for itsown sake in India. National energy securityconcerns also favor this conclusion sincecoal is the abundant national resource whilemost of the natural gas has to be imported.The analysis of contributing factors tothis disjoint indicates that sulfurreduction in petroleum oil products andpenetration of flue gas desulfurisationtechnologies are the two main contributorsfor sulfur dioxide (SO₂) mitigation.The reduction in particulate emissions ismainly due to enforcing electro-staticprecipitator efficiency norms in industrialunits, with cleaner fuels and vehicles alsocontributing substantially. These policytrends are already visible in India.Another insight is that high economicgrowth is better than lower growth tomitigate local pollution as lack ofinvestible resources limits investments incleaner environmental measures. Ouranalysis also validates the environmentalKuznets' curve for India as SO₂emissions peak around per capita GDP ofUS$ 5,300–5,400 (PPP basis) under variouseconomic growth scenarios.     

建筑废弃物资源化环境效益分析:以重庆为例

为了向政府提供可以提升建筑废弃物资源化环境效益的有利政策,以促进建筑废弃物资源化的可持续发展,本文从系统角度,应用系统动力学通过文献分析、实地调研、调查问卷等方法对建筑废弃物资源化的环境效益进行建模和模拟仿真.通过对环境效益模型进行情景分析,得出当非法排放单位罚款在50~60元/t,单位填埋收费取30元/t左右,建筑废弃物到资源化处置中心距离在15~25km左右,资源化的单位补贴额为25元/t左右时,可以使环境效益处于较优状态.同时政府应提高建筑废弃物相关法律的完善程度、培养相关人员的现场回收意识、促进相关科研研发,以期促进建筑废弃物资源化的环境效益.     

IMPACT OF VARIED DATA RESOLUTION ON HYDRAULIC MODELING AND FLOODPLAIN DELINEATION1

ABSTRACT: Current data collection technologies such as light detection and ranging (LIDAR) produce dense digital terrain data that result in more accurate digital terrain models (DTMs) for engineering applications. However, such data are redundant and often cumbersome for hydrologic and hydraulic modeling purposes. Data filtering provides a means of eliminating redundant points and facilitates model preparation. This paper demonstrates the impact of varied data resolution on a case study completed for a 2.3 mi² area with mild slopes (about 001 ft/ft) along Leith Creek near Laurinburg, North Carolina. For the original data set and seven filtered data sets, filtering induced changes in elevation, area, and hydraulic radius were determined for 10 water depths at 23 cross sections. Water surface elevations resulting from HEC‐RAS (Hydrologic Engineering Center‐River Analysis System) models for each data set were then compared. A hydraulic model sensitivity analysis was also conducted to compare filtering error to error introduced by variation in flow rates and roughness values. Finally, automated floodplain delineation was performed for each filter level based on the computed hydraulic model results and the filtered LIDAR elevations. Data filtering results indicate that significant time savings are achieved throughout the modeling process and that filtering to four degrees can be performed without compromising cross‐sectional geometry, hydraulic model results, or floodplain delineation results.