Geomorphological evolution and present-day processes in the Dessie Graben (Wollo,Ethiopia)

This paper presents a detailed geomorphological overview of the landforms and processes characterizing the Dessie basin, a small graben located on the western Afar Margin (Ethiopia), which is a physiographic province characterized by small, closed basins and mountain ranges produced by regional extension. Large-scale geomorphological survey and mapping of the basin allowed to point out the noteworthy morphodynamic role of the present-day slope processes, including numerous landslides of different typology and size. These processes heavily interact with the built-up area of Dessie town, one of the most important cities of Ethiopia with ca. 200,000 inhabitants, which occupies a large part of the basin floor. The potential incidence of landslides of different typology in the basin and their possible impact on the urban settlement are put in relation with the distribution of the different landform units which make up the basin surface.     

防疫通道喷雾消毒过程的数值模拟

防疫通道喷雾消毒是切断病毒传播的重要方式.以江苏大学与企业产学研合作研制的卫生防疫通道为基础,基于FLUENT仿真平台采用CFD双向耦合DPM方法,数值模拟了人员通过通道时喷雾和多相流场的分布情况.结果表明,雷诺数为1×10⁵左右,喷雾能够很好地分布在人体模型两侧;上排喷雾孔喷雾角为0°,该工况适合较高人员通过消毒通道;上排喷雾孔下倾10°,适合中学未成年人通过防疫通道;下排喷雾孔喷雾角向下倾斜30°时,喷雾主要分布在人体模型脚部附近,可满足对脚部的重点消毒需求.人体模型移动时会在模型周围形成大量的绕流,有利于提高消毒效率.通过适当调整上下排喷雾孔喷雾角,可以满足对人体模型局部重点消毒或整体覆盖消毒的不同需求.分析结果可以为卫生防疫通道设计与改进提供参考.     

气象干旱过程识别及致灾因子特征分析

为科学识别气象干旱及其发生、发展过程，并探究其致灾因子变化特征，通过1981—2020年海西州8个气象站点逐日气象干旱综合指数（Meteorological drought composite index，MCI）描述历年干旱事件，识别干旱过程个数、入旱出旱时间，分析干旱过程强度、干旱过程降水量等。结果表明：1981—2020年，海西州共识别干旱过程192个，干旱开始时间介于5月18日—6月20日之间，结束时间介于7月4日—8月8日之间，历时时长40~63 d；各等级干旱日数变化趋势不一，茫崖、乌兰县干旱日数变化呈增加趋势，变化倾向率分别为2.0 d·（10a）^-1，1.0 d·（10a）^-1，其余站点呈减小趋势，变化倾向率介于-4.0～-1.0 d·（10a）^-1。不同干旱等级的干旱日数大体呈中部少，西部多的态势，西南地区干旱最为严重；时间序列上，轻、中、重、特旱日数和年最长连续干旱日数呈减少趋势；年最长连续干旱日数均值为16 d，最大值为65 d （1995年）；茫崖干旱过程强度最高，天峻和都兰相对较低。     

Exploring the use of a dialogue process to tackle a complex and controversial issue in forest management

This article explores the use of a dialogue process to approach complex issues related to forest management. An interdisciplinary research team set up an experimental dialogue process concerning the use of introduced tree species in Southern Sweden for the purposes of climate change adaptation. The process involved stakeholders at a regional level, including those with divergent opinions regarding introduced tree species and their use in forestry. Through a process of repeated meetings and exchanges with researchers, the participant's knowledge was deepened and group relationships developed such that the group was able to jointly formulate a set of policy recommendations. The investigation revealed that dialogue processes may improve decision-making by identifying priorities for action or further research. However, when a collaborative process targets complex environmental issues on larger geographical and temporal scales, as matters about forests typically do, a collaborative process must be integrated with external actors and institutions in order to attain tangible outcomes. Consequently, to fully access the benefits of using collaborative processes to handle complex challenges in forest policy and management, the connections between political sphere, the private sector, authorities and research institutions must be concretely established.     

Surface runoff processes and sustainable utilization of water resources in Manas River Basin, Xinjiang, China

Water is the important resource to guarantee the existence and development of oases in arid areas. To improve the utilization efficiency of water resources in Manas River Basin, this paper investigated the trends and periods of runoff based on the runoff and climate data for the past 50 years. Subsequently, with the socioeconomic and water resources data, we studied a comprehensive evaluation on the water security in this area. The results indicated that the stream flows in the three hydrological stations of Hongshanzui, Kensiwat and Bajiahu have significantly increased and undergone abrupt changes, with periods of 18 and 20 years. According to assessment, water security in the Manas River Basin was at an unsafe level in 2008. In criterion layer, the ecological security index and the index of supply-demand situation are both at the relatively secure level; the quantity index and socioeconomic index of water resources are at the unsafe level and basic security level, respectively. Therefore, in order to achieve sustainable economic and social development within the Manas River Basin, it is vital to take a series of effective measures to improve the status of water security.     

Soil degradation processes and their control in Hungary

Soil degradation is usually a complex process in which several features of soil deterioration can be recognized. Soil degradation may lead to the loss of land or soil; limitations to normal soil functions; decrease of soil fertility and ‘productive capacity’. The main soil degradation process are: (1) soil erosion by water and wind; (2) Development of extreme soil reaction (acidification; salinization/alkalization); (3) physical degradation (structural destruction; compaction; extreme moisture regime); (4) biological degradation; (5) unfavourable changes in the nutrient regime; (6) decrease of buffering capacity (leading to pollution, toxicity). Soil degradation is not an unavoidable consequence of intensive agriculture and social development. Most of the processes and their unfavourable consequences can be controlled, prevented, eliminated, or at least moderated. A rational strategy of efficient soil degradation control should be based on a system involving the following (consecutive) steps: (a) registration of facts and consequences; (b) analysis of reasons, processes, influencing factors and their mechanisms; (c) determination of the theoretical, real, rational and economic possibilities for control; (d) prediction of the potential impacts of these control alternatives; (e) elaboration and extension of technologies for the optimum alternatives. The present status of soil degradation processes in Hungary is briefly summarized in this paper and the possibilities for control are reviewed, with special regard to soil erosion, salinization/alkalization, acidification and physical degradation (compaction, structure destruction). Based on detailed and comprehensive information on soils (thematic maps of various scales; computerized geographical soil information system) the potential future development of various soil degradation processes is forecast and technologies are elaborated and recommended for use in Hungarian agriculture to prevent soil degradation.     

Spatial and temporal dynamics of land degradation and fluvial erosion in the middle and upper Yangtze River Basin,China

Land degradation in the middle and upper Yangtze has caused loss of cultivable land, sediment deposition in reservoirs and changes in the runoff: sediment yield relationships of major tributaries. The Jialin River and the Dukou-Pingshan sector of the Jingsha River together contribute over 75 per cent of all the sediment carried by the Yangtze at Yichang. As the Jialin catchment has the highest rates of erosion per unit area, high sediment discharges from that river exert a major influence on peak summer sediment discharges on the Yangtze. Even though land degradation is increasing in severity, there is no clear overall pattern or trend in variations in sediment yield since 1950. Some tributaries are affected by major reservoir construction and soil conservation works, others are not.     

Environmental similarity is more important than distance in the community structuring processes of ammonia-oxidizing archaea in agricultural soils

Ammonia-oxidizing archaea(AOA) are important in converting ammonia into nitrate in soils. While many aspects of their community structure have been studied, the relative importance of stochastic versus deterministic processes has poorly been understood. We compared AOA communities across the North China Plain, targeting the amoA gene. A phylogenetic null modelling approach was used to calculate the beta nearest taxon index to quantify the influence of stochastic and deterministic processes. We f...     

Toward process‐based conservation prioritizations for freshwater ecosystems

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