Exploring the factors affecting urban ecological risk: A case from an Indian mega metropolitan region

Assessment of ecological risk (ER) is a key approach to adapting and mitigating ecological deterioration in cities of developing countries. In developing countries, the ecological landscapes such as vegetation cover, water bodies, and wetlands are highly vulnerable due to rapid urban expansion. Therefore, urban ER (UER) assessment and its drivers are crucial to guide ecological protection as well as restoration. This study aims to explore the spatiotemporal pattern of UER and the impact of urban spatial form on UER in the Kolkata Megacity Region (KMR), India. This study developed a UER index and used spatial regression models across the urban centres. The ER has been assessed at city scale as well as grid-scale (2 km × 2 km and 5 km × 5 km) from 2000 to 2020. The results showed that ER has substantially increased over the last 20 years. The urban centres with very high and high ER substantially increased, i.e. from 21.95% in 2000 to 31.70% in 2020. Kolkata and its surrounding urban centres were mostly characterized by very high and high ER. ER was influenced by spatial variables (such as land use and landscapes pattern). However, remote sensing parameters were weakly related to ER. The spatial lag model (SLM) (R² = 0.8686) was found to be better fit model than spatial error model (SEM) (R² = 0.8661) and ordinary linear regression model (OLS) (R² = 0.8641). Thus, the findings of the study can improve research and a comprehensive framework for urban ecological resources and provide a scientific basis for urban ecosystem planning and restoration. In addition to this, it will guarantee the sustainable utilization of urban ecosystems.     

Flow fields around tandem and staggered piers on a mobile bed

An experimental investigation on flow fields within the scour holes upstream and downstream of circular piers positioned in tandem and staggered arrangements is reported and compared with isolated piers on mobile beds with uniform sediment. The instantaneous bed elevations and instantaneous three dimensional (3D) velocities were measured using a 5 MHz Ultrasonic Ranging system and 16 MHz micro down looking acoustic Doppler velocimeter, respectively. The velocity and flow depth were measured at different locations under near equilibrium bed scour conditions. The measured 3D velocities were processed for the computation of flow parameters, such as velocity fields, streamline patterns, vorticity fields, and circulation. Furthermore, turbulence intensities, turbulent kinetic energy, Reynolds shear stresses, and bed shear stresses around the piers for all three pier configurations were computed from the detrended velocity signals to identify significant differences in the flow parameters and turbulence in the tandem and staggered pier arrangements as compared to those for an isolated pier. A recirculation zone was found near the bed in front of the rear pier in the tandem case from the streamline patterns. The vortices in the bi-vortex system were observed to be opposite to each other in the gap between the three piers in the staggered case. A strong secondary vortex also was observed apart from the primary vortex at the foot of the pier (θ = 0°) in all the three configurations. The strength of the horseshoe vortex (combination of primary and secondary vortices) was found to be higher at the front piers of the staggered arrangement as compared to those of the tandem piers, followed by the isolated pier. The bed shear stresses were found to be higher for the staggered piers than for the tandem piers in the direction of flow (θ = 0°). However, a 50% reduction in the bed shear stresses was observed behind the tandem piers at θ = 180°. The study reported in this paper provides the foundation for further investigation of countermeasures against local scour around tandem and staggered bridge piers on a mobile bed with non-uniform sediment.     

四川尔呷地吉铅锌矿区复杂地层钻探施工技术

四川尔呷地吉铅锌矿区位于南北向甘洛-小江断裂（本区内称为马拉哈断裂）北段与马拉哈背斜的复合部位。区域地质条件复杂,岩层破碎、裂隙发育,存在钻孔坍塌、漏失、缩径、掉块等钻探难题。为避免井内复杂事故、缩减钻井周期、降低作业风险,在该矿区开展了钻探技术研究工作。以ZK4522、ZK4737、ZK7545钻孔施工问题为例,重点剖析了钻孔事故频发的原因,提出了改进措施,总结了适合该矿区钻探施工的钻孔结构设计,并对不同地层使用冲洗液配方进行了阐述,对水泥浆护壁工艺、套管护壁工艺采取了技术管控措施,在该矿区取得了良好的效果,形成了一套具有实际参考价值的钻探施工方案,为该矿区以后的施工提供了技术保障措施和经验,同时对其他类似钻探施工也具有一定的借鉴意义。     

使用纳米碳酸钙降低低孔低渗煤层气储层伤害

传统暂堵剂难以封堵低孔低渗煤层气储层中的大量纳米级别孔隙.通过煤岩显微观测、钻井液基本性能测试、泥饼清除实验、煤岩孔隙分布实验和气体渗透率实验,探讨了纳米碳酸钙降低低孔低渗煤层气储层伤害的效果.结果表明:纳米碳酸钙材料只有在水溶液中保持纳米级的分散状态,才可能对低渗煤岩起到暂堵作用;基于纳米碳酸钙的可降解钻井液既能封堵低孔低渗煤岩中微米级别孔隙,也能封堵其中的纳米级别孔隙;经过生物酶和稀盐酸双重解堵后,煤岩渗透率恢复值达77.17%~97.98%,储层保护效果好;煤岩孔隙分布实验可以在纳米尺度上研究纳米材料对低孔低渗储层的暂堵效果.研究成果可为纳米碳酸钙在低孔低渗煤层和页岩钻完井过程中的应用奠定良好技术基础.      

加强钻探工程管理工作的措施和建议

从质量管理、效率管理、技术管理、环境保护、资质管理等几个方面提出了加强钻探工程管理工作的若干措施和建议,以期提高地质岩心钻探的质量和效率,实现经济效益最大化和勘查成果的准确性。     

基坑围护钢筋混凝土支撑精确爆破拆除

介绍了南京新城科技园国际研发总部园基坑支撑体系精确爆破拆除实例。针对大面积、大体量的支撑拆除,提出了精确爆破参数、科学起爆网络、可靠安全防护措施方案,取得了良好的爆破效果。     

基于生态工程的海岸带全球变化适应性防护策略

在全球变化导致的海平面上升和灾害性气候等压力下,我国海岸带风暴潮、海岸侵蚀、地面沉降等灾害发生频率和强度正在增加,对海岸防护体系的需求日益提高。传统海岸防护工程维护成本高,更新困难,而且可能造成地面沉降、水质恶化、生态退化、渔业资源衰退等后果。基于生态工程的海岸防护提供了抵御海岸带灾害的新理念。修复和重建沙滩、红树林、沼泽湿地、珊瑚礁等海岸带生态系统,可以起到消浪、蓄积泥沙、抬升地面的作用,有效应对全球变化引发的灾害风险,形成更可持续的海岸防护体系。通过分析不同海岸防护技术的优势和限制,认为以生态工程为核心理念构建和管理我国海岸防护体系,才能起到保障社会经济发展和维持生态健康的最佳效果。     

沿边开放开发进程中农用地多功能性评价

农用地多功能利用是黑龙江省沿边开放带土地利用效率提升及生态经济协调发展的客观要求,农用地利用多功能性评价是其基础工作。该文系统地研究了农用地利用多功能性评价方法,测度了1996年、2004年、2013年黑龙江省农用地利用多功能状态及期间变化。研究表明,1996~2013年黑龙江省农用地利用总功能缓慢提高,多功能协调性逐步提升;农用地利用由单一功能逐渐向多功能转变。为扩大农用地利用多功能整体效应并提高农用地利用多功能协调性,稳定生产功能、加快提高经济功能、重点遏制生态功能退化、逐步提高社会功能是沿边开放带今后的农用地利用方向。     

陕西省明长城文物保护监测

结合地理国情普查试点工作的技术和方法,详细阐述了陕西省明长城文物保护监测生产过程中地理国情要素信息提取方法,获取明长城监测数据,对监测成果进行统计分析,总结明长城文物保护监测生产技术方法,并提出保护明长城的建议.     

吉林省文物保护管理系统的设计与建立

文物是不可再生的文化资源,利用先进的测绘技术助力文物保护管理智慧平台的建设,将吉林省文物局现有的文物信息管理平台与地理信息时空数据相挂接,实现文物的查询、属性、分布、统计等功能与地形图相关联,是切实可行的。