Spatial analysis of resources and environmental carrying capacity in Iran

Urbanization and mass movement of the population from rural areas and small cities to megacities have led to environmental, economic, and social problems in Iran. In dealing with these challenges, assessing resource and environmental carrying capacity (RECC) is considered an effective method to leverage space and capital to achieve sustainable development. This study aimed to rank the provincial RECC in Iran. Toward this purpose, environmental indices were generated from remotely sensed and statistical census data. Then, the provinces were scored in terms of environmental, economic, and infrastructural carrying capacities, and RECC using the mean variance analysis method. Results demonstrated that in most areas, there is no relationship between economic and infrastructural capacities and development. Statistically, a correlation coefficient of −0.53 between economic and environmental carrying capacities indicated excessive use of environmental capacities. Moreover, the spatial distribution pattern of environmental, economic, and infrastructural carrying capacity was entirely heterogeneous between the provinces; there was a northeast–southwest pattern in terms of infrastructural capacity and an economic pattern from north to south. The distribution pattern of RECC is most consistent with the environmental capacity, pointing at the high weight of the indicators of the RECC model. In conclusion, this research offers a new vision for policymakers and provides a theoretical and applicable framework for implementing sustainable strategies in land-use planning. It is recommended that the RECC concept and tools can be used not only for planning but also for measuring the efficiency of spatial development programs and establishing land balances in the region.     

Temporal trends in agricultural water use and the relationships to hydroclimatic factors in the High Plains aquifer region

The High Plains aquifer (HPA) is the primary water source for agricultural irrigation in the US Great Plains. The water levels in many locations of the aquifer have declined steadily over the past several decades because the rate of water withdrawals exceeds recharge, which has been a serious concern to the water resources management in the region. We evaluated temporal trends and variations in agricultural water use and hydroclimatic variables including precipitation, air temperature, reference evapotranspiration, runoff, groundwater level, and terrestrial water storage across the HPA region for different periods from 1985 to 2020 at the grid, county, or region scale. The results showed that water withdrawals decreased from 21.3 km³/year in 1985 to 18.2 km³/year in 2015, while irrigated croplands increased from 71,928 km² in 1985 to 78,464 km² in 2015 in the entire HPA. The hydroclimatic time-series showed wetting trends in most of the northern HPA, but drying and warming trends in the southern region from 1985 to 2020. The groundwater level time-series indicated flat trends in the north, but significant declining in the central and southern HPA. Trends in irrigation water withdrawals and irrigation area across the HPA were controlled by the advancement of irrigation systems and technologies and the management of sustainable water use, but also were affected by dynamical changes in the hydroclimatic conditions.     

Impact of floodplain and Stage 0 stream restoration on flood attenuation and floodplain exchange during small frequent storms

River flooding impacts human life and infrastructure, yet provides habitat and ecosystem services. Traditional flood control (e.g., levees, dams) reduces habitat and ecosystem services, and exacerbates flooding elsewhere. Floodplain restoration (i.e., bankfull floodplain reconnection and Stage 0) can also provide flood management, but has not been sufficiently evaluated for small frequent storms. We used 1D unsteady Hydrologic Engineering Center's River Analysis System to simulate small storms in a 5 km-long, second-order generic stream from the Chesapeake Bay watershed, and varied % channel restored (starting at the upstream end), restoration location, restoration bank height (distinguishes bankfull from Stage 0 restoration), and floodplain width/Manning's n. Stream restoration decreased (attenuated) peak flow up to 37% and increased floodplain exchange by up to 46%. Floodplain width and % channel restored had the largest impact on flood attenuation. The incremental effects of new restoration projects on flood attenuation were greatest when little prior restoration had occurred. By contrast, incremental effects on floodplain exchange were greatest in the presence of substantial prior restoration, setting up a tradeoff. A similar tradeoff was revealed between attenuation and exchange for project location, but not bank height or floodplain width. In particular, attenuation and exchange were always greater for Stage 0 than for bankfull floodplain restoration. Stage 0 thus may counteract human impacts such as urbanization.     

The need for spatially explicit quantification of benefits in invasive‐species management

Worldwide, invasive species are a leading driver of environmental change across terrestrial, marine, and freshwater environments and cost billions of dollars annually in ecological damages and economic losses. Resources limit invasive‐species control, and planning processes are needed to identify cost‐effective solutions. Thus, studies are increasingly considering spatially variable natural and socioeconomic assets (e.g., species persistence, recreational fishing) when planning the allocation of actions for invasive‐species management. There is a need to improve understanding of how such assets are considered in invasive‐species management. We reviewed over 1600 studies focused on management of invasive species, including flora and fauna. Eighty‐four of these studies were included in our final analysis because they focused on the prioritization of actions for invasive species management. Forty‐five percent (n = 38) of these studies were based on spatial optimization methods, and 35% (n = 13) accounted for spatially variable assets. Across all 84 optimization studies considered, 27% (n = 23) explicitly accounted for spatially variable assets. Based on our findings, we further explored the potential costs and benefits to invasive species management when spatially variable assets are explicitly considered or not. To include spatially variable assets in decision‐making processes that guide invasive‐species management there is a need to quantify environmental responses to invasive species and to enhance understanding of potential impacts of invasive species on different natural or socioeconomic assets. We suggest these gaps could be filled by systematic reviews, quantifying invasive species impacts on native species at different periods, and broadening sources and enhancing sharing of knowledge.     

三峡水库浮游植物群落特征及水体富营养化评价

基于2003—2017年三峡水库浮游植物群落结构、优势种群的变化和2017年水库干支流水质数据,全面分析浮游植物群落结构和演替特征,并运用综合营养状态指数法对水体富营养化程度进行评价。结果表明,三峡水库浮游植物种类丰富,监测期间共鉴定出浮游植物7门62属,细胞密度在7.5×10~4~2.8×10~7cell/L之间变化,Shannon-Wiener多样性指数为1.0~3.0,在α-中污带和β-中污带之间,说明三峡水库水生态环境健康状况相对较好;三峡水库浮游植物季节性演替特征呈硅藻和甲藻向蓝藻和绿藻演替的趋势,年际变化特征分析发现浮游植物密度在2008年175 m实验蓄水后大量增长,且优势藻类由河道型藻类向湖泊型藻类转化。通过监测数据分析,得出三峡水库干流处于中营养状态,支流在春季主要处于轻度富营养状态,秋季支流比春季支流的富营养化程度低,主要处于中营养状态,总氮(total nitrogen,TN)、总磷(total phosphorus,TP)和透明度(transparency,SD)为水质主要影响因子。     

长三角空气质量区域预报准确性评估方法研究

根据长三角空气质量区域预报工作的实际需要,对分区文字预报和落区图预报两种方式分别制定了不同的空气质量指数级别预报准确性评估方法。分区文字预报根据设定的预报准确性判定方法计算预报评分,落区图预报按区域内预报准确城市占比进行准确率统计。分区文字预报结果显示,2017年长三角区域的预报准确天数占比为62.2%,预报评分为70.2,区域预报评估效果良好。落区图预报评估结果显示,预报级别偏差具有地域性差异,安徽北部、江苏北部和江西中北部预报等级偏高,长三角中南部沿海城市预报等级偏低。该套评估方法可为区域空气质量预报偏差成因分析提供依据,为区域预报工作的改进提供定量参考。     

基于云模型的高校消防安全标准化评估研究

为评估高校消防安全标准化程度,明确高校消防安全标准化体系,结合高校消防安全标准化体系的模糊性,将高校消防安全标准化等级划分为5个级别,采用黄金分割法将权重云、评价云划分成5个云模型,建立能够反映高校消防安全标准化等级模糊性的云模型。该模型运用于某高校消防安全标准化等级评估中,评估结果客观合理,实用性较强,为后续标准化提升提供了参考依据。     

可拓优度评价法在城市区域消防安全评价中的应用

为了解决城市区域消防安全评价的复杂性和不确定性,本文运用可拓优度评价法,根据相关文件并结合城市区域消防的实际情况,从火灾危险程度、城市区域特征、消防实力水平和社会管理状态4个方面选取17个指标,建立了城市区域消防安全评价指标体系并划分了消防安全等级,以洛阳市西工区为例对城市区域消防安全评价的可拓优度方法进行了验证。结果表明,可拓优度方法可以准确反映出该区域消防安全水平。     

间接蒸发冷却新风机组净化室内PM2.5特性

为有效降低室内PM2.5,指导间接蒸发冷却新风机组的设计选型,推导了新风机组净化效力和净化能效评价指标的数学表达式,并利用自行研制的间接蒸发冷却新风机组,分析了2种过滤器在不同运行工况下净化PM2.5的特性。结果表明,MERV 7+16和MERV 7+13的计数效率均随颗粒物粒径增加而提高,且前者的计数效率高于后者;由于滤材的不同,MERV 7+16的初阻力更小。MERV 7+16的渗透系数更小,其净化效力也要大于MERV 7+13;由于PM10在室内的自然沉降作用更显著,过滤器对PM10的净化效力明显大于PM2.5和PM1。将室内新风负荷作为新风机组能耗的一部分,在对比天津和南宁地区新风机组的净化能效时发现,由于两地区冬季室外温度存在明显差异,导致处于天津地区的新风机组若要在冬季获得同等的洁净空气量,需付出更多的能耗代价。     

Experimental research of LNG accidental underwater release and combustion behavior

Evaluating potential hazards caused by accidental LNG release from underwater pipelines or vessels is a significant consideration in marine transportation safety. The aim of this study was to capture the dynamic behavior of LNG jet released under water and to analyze its vapor dispersion characteristics and combustion characteristics on the water surface during different release scenarios. Controlled experiments were conducted where LNG was jet released from a cryogenic storage tank. The dynamic process of LNG being jet released from orifices of different sizes and shapes, as well as the rising plume structure, were captured by a high-speed camera. The leakage flow rate and pipeline pressure were recorded by a flow meter and pressure gauge, respectively. The concentration distribution that emanated from the water surface was measured utilizing methane sensors in different positions with various wind speeds. The flame combustion characteristics of LNG vapor clouds, which immediately ignited upon the enclosed water tank, were also recorded. Additionally, the mass burning rate of the flame on the water surface was evaluated, and a new correlation between the ratio of flame length and width was established. The results indicated a large dimensionless heat release rate (Q*) and a continuous release flow rate in a limited burning area. This study could provide greater understanding of the mechanisms of LNG release and combustion behavior under water.