Scenario-based assessment and multi-objective optimization of urban development plan with carrying capacity of water system

• Impact of urban development on water system is assessed with carrying capacity. • Impacts on both water resource quantity and environmental quality are involved. • Multi-objective optimization revealing system trade-off facilitate the regulation. • Efficiency, scale and structure of urban development are regulated in two stages. • A roadmap approaching more sustainable development is provided for the case city. Environmental impact assessments and subsequent regulation measures of urban development plans are critical to human progress toward sustainability, since these plans set the scale and structure targets of future socioeconomic development. A three-step methodology for assessing and optimizing an urban development plan focusing on its impacts on the water system was developed. The methodology first predicted the pressure on the water system caused by implementation of the plan under distinct scenarios, then compared the pressure with the carrying capacity threshold to verify the system status; finally, a multi-objective optimization method was used to propose regulation solutions. The methodology enabled evaluation of the water system carrying state, taking socioeconomic development uncertainties into account, and multiple sets of improvement measures under different decisionmaker preferences were generated. The methodology was applied in the case of Zhoushan city in South-east China. The assessment results showed that overloading problems occurred in 11 out of the 13 zones in Zhoushan, with the potential pressure varying from 1.1 to 18.3 times the carrying capacity. As a basic regulation measure, an environmental efficiency upgrade could relieve the overloading in 4 zones and reduce 9%‒63% of the pressure. The optimization of industrial development showed that the pressure could be controlled under the carrying capacity threshold if the planned scale was reduced by 24% and the industrial structure was transformed. Various regulation schemes including a more suitable scale and structure with necessary efficiency standards are provided for decisionmakers that can help the case city approach a more sustainable development pattern.     

Wood bison population recovery and forage availability in northwestern Canada

Forage availability was assessed to determine sustainable stocking rates for eight broadly defined vegetation types (Treed Uplands, Treed Lowlands, Mixed Tall Shrub/Sedge, Closed-canopied Willow, and Open-canopied Willow, Meadow, Wetland Grass, Wetland Sedge) for use by wood bison (Bison bison athabascae), a threatened subspecies, in the Canadian boreal forest of northern Alberta. Clip plots (n=108) were used to sample peak availability of herbs and current annual growth of Salix spp. in late summer. Graminoid wetlands dominated by Carex atherodes, Carex aquatilis, Carex utriculata, Scolochloa festucacea, or Calamagrostis stricta produced 1975-4575 kg ha(-1) of fair to good quality forage, whereas treed stands produced < 250 kg ha(-1) of forb-dominated forage (>85% content), which was below a published 25% foraging efficiency threshold of 263 kg ha(-1) for bison. Upland forests that dominate the region produced < or = 1 animal unit day (AUD) of forage per hectare in summer. Most forest understory plants were of poor forage value, suggesting the potential sustainable stocking rate of such areas was actually < or = 0.3 AUD ha(-1), with even lower rates during winter due to snow cover. Herbaceous wetlands contained approximately 78 AUD ha(-1) of forage, but were considered largely unavailable in summer because of flooding and soft organic soils that make access difficult. Conversion of prime foraging habitat to agricultural land, forest expansion due to fire control, and a warmer and wetter climatic regime after the mid-1900s likely contributed to a regional reduction in carrying capacity. It is hypothesized that substantial recovery of the wood bison population toward historical levels will be constrained in northern Alberta by the availability of summer forage, and the limited extent of graminoid wetlands that provide winter foraging habitat.     

关于推行清洁生产有关问题的探讨

阐述了清洁生产是可持续局长战略思想的具体体现,是实现可持续发展战略的必由之路。并提出了推行清洁生产的一些建议和设想。     

Review and appraisal of concept of sustainable food production systems

Environmental degradation, competition for resources, increasing food demands, and the integration of agriculture into the international economy threaten the sustainability of many food production systems. Despite these concerns, the concept of sustainable food production systems remains unclear, and recent attempts to appraise sustainability have been hampered by conceptual inconsistencies and the absence of workable definitions. Six perspectives are shown to underpin the concept. Environmental accounting identifies biophysical limits for agriculture. Sustained yield refers to output levels that can be maintained continuously. Carrying capacity defines maximum population levels that can be supported in perpetuity. Production unit viability refers to the capacity of primary producers to remain in agriculture. Product supply and security focuses on the adequacy of food supplies. Equity is concerned with the spatial and temporal distribution of products dervied from resource use. Many studies into sustainable agriculture cover more than one of these perspectives, indicating the concept is complex and embraces issues relating to the biophysical, social, and economic environments. Clarification of the concept would facilitate the development of frameworks and analytical systems for appraising the sustainability of food production systems. LRRC Contribution No. 90–46.     

陕西渭南地区土地生产潜力及其人口承载量

本文以多年大量的资源考察、经济统计资料为依据,运用系统动力学方法,通过建立包括土地资源、水资源和种植业、畜牧业、渔业等为主的土地生产潜力模型及人口发展预测模型,对未来40年渭南地区不同投入状况下土地生产潜力及其不同消费水平下的人口承载量,作了趋势性定量分析和预测,并得出渭南地区具有较大的土地潜在人口支持能力的基本结论。     

Carrying Capacity:An Overview

The concept of carrying capacity is derived from ecology, with widespread contentions of its theoretical connotations and applications in the international academic community, especially the impact of human activities on the environment. Disputes on carrying capacity have been occurring not only among biologists and ecologists, but also among mainstream economists. Based on their efforts, the author makes an attempt to describe its origin, connotations, problems, measurement, and at the same time note the latest international progress in this field.     

Conceptual framework for evaluation of ecotourism carrying capacity for sustainable development of Karkheh protected area,Iran

The maintenance of natural and virgin ecosystems against an unnecessary influx of humans requires a modern and efficient model such as the carrying capacity model to optimize the management and development of ecotourism in these areas. The model is one of the key tools for conservation and sustainability of these areas. The present research attempts to formulate a framework for the ecotourism carrying capacity model for sustainable development of Karkheh protected area in Iran. The information was collected using a citation method as well as, interviews with experts, and visitors, and director of the region with 24 key indicators being regulated by field surveys and library studies. In this study, the network analysis process model, the Pressure-State-Response conceptual model, and Arc GIS_10.5 software were used to determine the potential for the establishment of ecotourism performance in the scale of 1: 50,000. In this research, 70 questionnaires were completed by experts in the field of environment and ecotourism to determine the relative importance of effective pressures. According to the results, the highest values belonged to physical carrying capacity (13,425,681 persons per day), ecological carrying capacity (2,482,226 persons per day), and social and culture (985,706 people per day), respectively. Based on the regional carrying capacity, the physical, ecological, and social carrying capacity index was calculated as 3356, 621, and 246 (greater than one), respectively. According to the results, the region has a high carrying capacity, which can accept visitors.     

基于均方差决策法的辽宁省城市综合承载力研究

通过构建评价指标体系,并基于均方差决策方法确立指标权重,构建综合承载力评价模型,对辽宁省14个地级市综合承载力展开分析。结果表明,研究区内资源、环境承载力供需指数比普遍偏低,14个地级市中环境承载力供需指数比大于1的比例不足10%,资源承载力比例不足30%。不同城市各要素承载力及综合承载力均存在显著差异,其中,大连、沈阳综合承载力最高,本溪、丹东资源承载力最高,辽阳、盘锦环境承载力较低,沈阳和大连经济承载力较高,各城市社会承载力总体较高。此外,资源与经济承载力对研究区城市综合承载力的影响最大,但是研究区城市发展的限制性因素是环境,未来应着重根据各市环境短板确定未来严格的环境保护目标与管理体制,有效提升城市环境承载力。     

Measurement and assessment of carrying capacity of the environment in Ningbo, China

Carrying Capacity of the Environment (CCE) provides a useful measure of the sustainable development of a region. Approaches that use integrated assessment instead of measurement can lead to misinterpretation of sustainable development because of confusion between Environmental Stress (ES) indexes and CCE indexes, and the selection of over-simple linear plus models. The present paper proposes a comprehensive measurement system for CCE which comprises models of natural resources capacity, environmental assimilative capacity, ecosystem services capacity, and society supporting capacity. The corresponding measurable indexes are designed to assess CCE using a carrying capacity surplus ratio model and a vector of surplus ratio of carrying capacity model. The former aims at direct comparison of ES and CCE based on the values of basic indexes, and the latter uses a Euclidean vector to assess CCE states. The measurement and assessment approaches are applicable to Strategic Environmental Assessment (SEA) and environmental planning and management. A case study is presented for Ningbo, China, whereby all the basic indexes of ECC are measured and the CCE states assessed for 2005 and 2010.     

Calculating ecological carrying capacity of shellfish aquaculture using mass-balance modeling: Narragansett Bay, Rhode Island

Increasing growth in the aquaculture industry demands ecosystem-based techniques for management if that growth is to be ecologically sustainable and promote equity among users of the ecosystems in which it occurs. Models of carrying capacity can be used to responsibly limit the growth of aquaculture in increasingly crowded coastal areas. Narragansett Bay, Rhode Island, USA is one such crowded coastal region experiencing a rapid increase in bivalve aquaculture. An ecosystem mass-balance model was used to calculate the ecological carrying capacity of bivalve aquaculture. Cultured oyster biomass is currently at 0.47 t km⁻² and could be increased 625 times without exceeding the ecological carrying capacity of 297 t km⁻². This translates to approximately 38,950 t of harvested cultured oysters annually which is 4 times the total estimated annual harvest of finfish. This potential for growth is due to the high primary productivity and large energy throughput to detritus of this ecosystem. Shellfish aquaculture has potential for continued growth and is unlikely to become food limited due, in part, to the large detritus pool.