混凝土膨胀剂使用中存在的问题及解决措施

混凝土膨胀剂具有补偿混凝土干燥收缩的效果,但在地下室防水混凝土工程中,使用效果不理想,存在掺加膨胀剂后地下室底板和外墙出现混凝土开裂渗漏的现象。本文从设计源头,力求全面地、准确有效地提出解决措施。     

遥感影像时—空融合的“点”—“线”—“面”质量评价

遥感影像时—空融合可集成多源数据高空间分辨率和高时间分辨率互补优势,生成时间连续的高空间分辨率影像,在遥感影像的动态监测与时序分析等方面具有重要应用价值.然而,现有多数研究往往基于单一数据产品对时—空融合算法进行评价,而在实际生产应用中,需要验证算法在多种遥感产品数据的融合表现;此外,目前研究大多基于“单点时刻”进行评...     

Riparian land use and stream habitat regulate water quality

Riparian land use is a key driver of stream ecosystem processes but its effects on water quality are still a matter of debate when proposing measures to improve freshwater quality. The aim of this study was to examine the influence of riparian land use on stream habitat and water chemistry, and to assess in what extent stream habitat also affects water quality. To that end, we selected eight reaches in the Ave River basin (northwestern Portugal) and compared longitudinal variations in water chemistry and stream habitat between reaches with different land use (urban, agricultural and natural), and between reaches with natural riparian areas and different habitats. Stream habitat was assessed using the Fluvial Functional Index, the HABSCORE, and the Riparian Forest Quality Index. Longitudinal variations in water chemistry were determined measuring differences in concentrations of ammonium, nitrate, phosphate and oxygen, and conductivity, pH and temperature between the downstream and the upstream ends of each reach. Nitrate concentration tended to decrease along reaches with more natural riparian areas and to increase along reaches with more urban and agricultural land uses. Longitudinal variations in water chemistry also differed between reaches with natural riparian areas, suggesting that water quality also depends on stream habitat. Moreover, longitudinal variation in water chemistry was proven a simple, useful and low-cost approach to assess the influence of land cover and stream habitat on water quality. Overall results demonstrated that both riparian land use and stream habitat influence water quality and that riparian forests are essential to reduce nutrient export to downstream ecosystems.     

土地综合整治项目成功范例分析——以临沂市兰山区李官镇为例

通过阐述临沂市兰山区李官镇土地综合整治项目实施这一成功范例,提出实施土地综合整治项目应抓住的6个关键环节,分析了每个环节的作用和操作方法,希望对破解当前土地综合整治项目实施难的问题有所帮助。     

Background concentrations of elements in surface soils and their changes as affected by agriculture use in the desert-oasis ecotone in the middle of Heihe River Basin,North-west China

The concentrations of twenty four chemical elements in the surface layer of natural desert soils and the cultivated farmland soils were measured at a desert-oasis ecotone in the middle of Heihe river basin, north-west China. Background values were estimated for (a) major elements (Si 335.3 g kg^− 1, Al 49.4 g kg^− 1, Fe 19.1 g kg^− 1, Ca 29.4 g kg^− 1, Mg 8.9 g kg^− 1, K 20.1 g kg^− 1, Na 17.5 g kg^− 1 and P 0.338 g kg^− 1), (b) heavy metals and non-metals (Cr 55.8 mg kg^− 1, Mn 404.8 mg kg^− 1, Ni 17.7 mg kg^− 1, Cu 5.1 mg kg^− 1, Zn 33.7 mg kg^− 1, Pb 15.5 mg kg^− 1 and As 5.2 mg kg^− 1) and (c) other trace elements (Ti 2.0 mg kg^− 1, V 55.3 mg kg^− 1, Co 5.7 mg kg^− 1, Rb 82.4 mg kg^− 1, Sr 232.9 mg kg^− 1, Y 14.7 mg kg^− 1, Zr 194.9 mg kg^− 1, Nb 7.8 mg kg^− 1 and Ba 720.6 mg kg^− 1). After natural desert soil was cultivated for agricultural use, significant changes in element concentrations occurred under tillage, irrigation and fertilisation management. Compared to natural soil, the for the levels of Si, K, Na, Sr, Zr and Ba decreased, and no changes were observed for Rb, while the values of the other 17 elements increase in agricultural soil from 1.2 to 3.5 times. However, their absolute concentrations are still low, suggesting that the arable soil in this region remains comparatively a clean soil. The increased silt, clay and organic carbon content, under long-term irrigation, enriched the fine-grained materials, and application of fertilisers and manure contributed to the accumulation of most elements in arable soil. The accumulation of elements in agricultural soil increased with increasing cultivation years and extent of soil development.     

国土资源行业“3S”技术集成研究及实用技术体系构建

本文面向国土资源信息化建设的实际需求,通过关键技术研究和技术集成,建立基于“3S”的国土资源数据获取、更新、管理、交换与应用的技术体系,通过应用示范研究,形成实用、可推广的技术流程和应用软件。研究结果表明,基于“3S”的技术体系,以其精确的空间定位、快速准确的数据获取、强大的数据管理能力,能够满足国土资源信息化建设的实际需要。     

土地利用现状空间数据库拓扑关系分析及基于规则的高效检测

为了提高土地利用现状空间数据库空间数据检测效率,实现要素类拓扑关系的智能检测,在分析详查要素拓扑关系的基础上,提出基于拓扑规则的拓扑关系验证方法。并采用GIS开发平台ArcEngine,基于RSTT质检模型,研制了空间数据质检系统LR_Checker。经大量土地利用现状空间数据的测试表明,采用LR_Checker可显著提高数据检测效率,通过规则的逻辑组合,不仅实现要素类内拓扑关系检测,还支持不同要素类间拓扑关系检测。证明了基于拓扑规则的拓扑关系验证方法的正确性、有效性和合理性。     

矿业城市土地利用/覆被变化的水文效应研究

矿业城市受到矿山开发与城市扩张的双重影响,生态环境遭到严重破坏,水环境问题尤为突出。本文以煤矿城市河南省鹤壁市为研究区,根据汤河流域1970—2015年土地利用覆被时空变化特征设定5种不同时期土地利用情景,采用SWAT模型模拟分析5期土地利用/覆被变化的水文效应以及变化规律。研究结果显示,1970—2015年间,土地利用变化引起流域内蒸散发量、土壤下渗量和地下径流量年均分别减少-1. 48 mm、-0.38 mm、-0.29 mm,地表径流量年均增加0.76 mm,汛期与非汛期径流增加;在不同水文年份,土地利用变化对平水年的年径流影响最为明显,对枯水年年径流的影响大于丰水年。本文主要提出了以矿业城市土地利用变化对水循环的影响,该方法对矿区范围内水资源的科学管理具有一定的参考意义。     

Resilience as transformative capacity: Exploring the quadripartite cycle of structuration in a Mozambican resettlement programme

The concept of resilience has emerged out of a complex literature that has sought to make sense of an increasingly interconnected world that appears ever more beset by crises. Resilience’s appeal is reflected by the burgeoning mass of literature that has appeared on the subject in the past five years. However, there is ongoing debate surrounding its usage, with some commentators claiming that the term is inherently too conservative a one to be usefully applied to situations of vulnerability in which more radical social change is required. This article extends existing efforts to formulate more transformative notions of resilience by reframing it as a double-edged outcome of the pre-reflective and critical ways in which actors draw upon their internal structures following the occurrence of a negative event, thus reproducing or changing the external structural context that gave rise to the event in the first place. By employing a structuration-inspired analysis to the study of small-scale farmer responses to a flood-induced resettlement programme in central Mozambique, the article presents a systematic approach to the examination of resilience in light of this reframing. The case study findings suggest that more attention should be paid to the facilitative, as well as constraining, nature of structures if vulnerable populations are to be assisted in their efforts to exert transformative capacity over the wider conditions that give rise to their difficulties.     

地面沉降对渤海湾风暴潮灾害防治的影响研究

渤海湾沿海地区地面沉降严重、风暴潮灾害频发。本文以天津作为典型区域,对风暴潮潮位测定、风暴潮灾害和防风暴潮预案措施等方面开展研究,认为地面沉降对上述3方面均有的不同程度的影响,在风暴潮灾害防治中必须考虑地面沉降问题。