Historical and potential changes of precipitation and temperature of Alberta subjected to climate change impact: 1900–2100

We investigated changes to precipitation and temperature of Alberta for historical and future periods. First, the Mann-Kendall test and Sen’s slope were used to test for historical trends and trend magnitudes from the climate data of Alberta, respectively. Second, the Special Report on Emissions Scenarios (SRES) (A1B, A2, and B1) of CMIP3 (Phase 3 of Coupled Model Intercomparison Project), projected by seven general circulation models (GCM) of the Intergovernmental Panel on Climate Change (IPCC) for three 30 years periods (2020s, 2050s, and 2080s), were used to evaluate the potential impact of climate change on precipitation and temperature of Alberta. Third, trends of projected precipitation and temperature were investigated, and differences between historical versus projected trends were estimated. Using the 50-km resolution dataset from CANGRD (Canadian Grid Climate Data), we found that Alberta had become warmer and somewhat drier for the past 112 years (1900–2011), especially in central and southern Alberta. For observed precipitation, upward trends mainly occurred in northern Alberta and at the leeward side of Canadian Rocky Mountains. However, only about 13 to 22 % of observed precipitation showed statistically significant increasing trends at 5 % significant level. Most observed temperature showed significant increasing trends, up to 0.05 °C/year in DJF (December, January, and February) in northern Alberta. GCMs’ SRES projections indicated that seasonal precipitation of Alberta could change from ?25 to 36 %, while the temperature would increase from 2020s to 2080s, with the largest increase (6.8 °C) in DJF. In all 21 GCM-SRES cases considered, precipitation in both DJF and MAM (March, April, and May) is projected to increase, while temperature is consistently projected to increase in all seasons, which generally agree with the trends of historical precipitation and temperature. The SRES A1B scenario of CCSM3 might project more realistic future climate for Alberta, where its water resources can become more critical in the future as its streamflow is projected to decrease continually in the future.     

Assessment of climate change impacts on flooding vulnerability for lowland management in southwestern Taiwan

Taiwan suffers from losses of economic property and human lives caused by flooding almost every year. Flooding is an inevitable, reoccurring, and the most damaging disaster in Taiwan since Taiwan is located in the most active tropic cyclone formation region of the Western Pacific. Flooding problem is further worse in land subsidence areas along southwestern coast of Taiwan due to groundwater overdraft. Increasing number of people is threatened with floods owing to climate change since it would induce sea level rise and intensify extreme rainfall. Assessments of flooding vulnerability depend not only on flooding severity, possible damage of assets exposed to floods should also be simultaneously considered. This paper aims at exploring how climate change might impact the flooding vulnerability of lowland areas in Taiwan. A flooding vulnerability evaluation scheme is proposed in this study which incorporates flooding severity (the maximum inundation depth determined by a two-dimensional model) and potential economic losses for various land uses. Effects of climate change on flooding vulnerability focus on alterations of rainfall depth for various recurrence intervals. The flood-prone Yunlin coastal area, located in southwestern Taiwan, is chosen to illustrate the proposed methodology. The results reveal that reducing flooding vulnerability can be achieved by either reducing flooding severity (implementation of flood-mitigation measures) or decreasing assets exposed to floods (suspension of land uses for flood-detention purpose). Performance of currently implemented flood-mitigation measures is insufficient to reduce flooding vulnerability when facing with climate change. However, the scenario suggested in this study to sustain room for floods efficiently reduces flooding vulnerability in both without- and with climate change situations. The suggestions provided in this study could support decision processes and help easing flooding problems of lowland management in Taiwan under climate change.     

Simulation and optimization model for irrigation planning and management

A simulation and optimization model was developed and applied to an irrigated area in Delta, Utah to optimize the economic benefit, simulate the water demand, and search the related crop area percentages with specified water supply and planted area constraints. The user interface model begins with the weather generation submodel, which produces daily weather data, which is based on long‐term monthly average and standard deviation data from Delta, Utah. To simulate the daily crop water demand and relative crop yield for seven crops in two command areas, the information provided by this submodel was applied to the on‐farm irrigation scheduling submodel. Furthermore, to optimize the project benefit by searching for the best allocation of planted crop areas given the constraints of projected water supply, the results were employed in the genetic algorithm submodel. Optimal planning for the 394·6‐ha area of the Delta irrigation project is projected to produce the maximum economic benefit. That is, projected profit equals US$113 826 and projected water demand equals 3·03 × 10⁶ m³. Also, area percentages of crops within UCA#2 command area are 70·1%, 19% and 10·9% for alfalfa, barley and corn, respectively, and within UCA#4 command area are 41·5%, 38·9%, 14·4% and 5·2% for alfalfa, barley, corn and wheat, respectively. As this model can plan irrigation application depths and allocate crop areas for optimal economic benefit, it can thus be applied to many irrigation projects. Copyright © 2003 John Wiley & Sons, Ltd.     

内蒙古白乃庙铜矿区含矿中酸性侵入岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及成矿时代

为了限定白乃庙铜矿的成矿时代和成矿环境,对含矿中酸性岩类进行同位素年龄和岩石地球化学研究。获得的3个含矿花岗闪长岩样品的LA-MC-ICP-MS锆石U-Pb年龄分别为421.5±1.8Ma、438.6±3.4Ma和459.3±3.6Ma。含矿中酸性岩类属于过铝质钙碱性系列岩石,稀土元素曲线显示为轻稀土元素富集型,具有弱正Eu异常,微量元素曲线表现为明显的Ta、Nb亏损。综合含矿中酸性岩类时代、地球化学特征及区域构造背景,认为白乃庙铜矿总体形成于早古生代,具有多期成矿的特点,成矿作用与古蒙古洋早古生代俯冲消减事件有关。     

吉林一次极端降水发生发展动热力过程的数值模拟分析

利用ERA-Interim再分析资料、常规气象观测资料、CMORPH（CPC MORPHing technique）融合降水资料以及WRF（Weather Research and Forecasting）高分辨率数值模拟结果,对2017年7月13～14日吉林地区的极端降水天气过程的环流背景和触发机制进行了分析。结果表明:（1）东北冷涡环流控制下,副高北抬与中纬度锋区形成了有利的大尺度环流背景。降水发生在冷涡底部与副高之间的平直纬向环流中,东北冷涡南部的低槽、低空切变线、高低空急流是影响此次降水的重要天气系统;（2）在高层辐散低层辐合的有利动力条件下,极端的水汽输送与吉林地区西低东高地形的阻挡和强迫抬升是极端降水产生的重要原因;（3）中高层有干冷空气入侵,伴随高空动量下传至低空,加强了低空急流发展,低空急流发展至地面附近产生超低空急流后,加强了上升运动。南北经向动量输送交汇加强了低层风辐合切变,切变线上对流发展与永吉附近小地形的抬升作用,诱导永吉县产生极端降水。     

物联网与云技术支持下的水平角测量信息化实训教学设计

针对工程测量专业学生实训过程观测数据无法监测的问题,基于水平角测量基本流程及教学案例,开发了云教学平台。该平台把物联网、云技术和测绘专业知识进行了综合。云教学平台应用于教学,丰富了信息化教学手段,提高了授课水平;同时全站仪的物联网化也为测绘实际生产工作带来新的思路。本研究解决了教学问题,且具有实际应用意义。     

Study of Water Relative Permeability in Fractures Using Well Tests and Radon: Gas Bubbles Effect

Few published data are available for two-phase flow in fractures from field studies. All measurements of relative permeability reported in the literature were done in laboratory-scale. The in situ water saturations are normally not known for multiphase flow in natural fractures; therefore, the direct measurements of relative permeability are difficult in field-scale. With the help of a case study before and after the 2008 M_w 5.4 Antung earthquake, groundwater radon was used as a tracer to determine the gas and water saturations in a small naturally fractured aquifer. Well tests were also conducted to estimate aquifer transmissivity before and after the 2008 Antung earthquake. Anomalous declines in both groundwater radon concentration and transmissivity were observed precursory to the 2008 Antung earthquake. Both declines are two precursory phenomena having a common effect of gas bubbles. Using the data from well tests and radon tracer, one data point of water relative permeability can be obtained for in situ fractures. This data point reveals strong phase interference between water and gas bubbles for multiphase flow in natural fractures. Both the data of well tests and radon tracer are essential to gain an improved understanding of mass transfer behavior of groundwater-dissolved gases between water and gas phases.     

基于EEMD及BP神经网络的区域海平面多尺度预测研究

基于时间序列的统计预测模型是现阶段海平面高度预测的主要手段之一,然而海平面变化机理复杂,传统方法对于非平稳非线性的时间序列预测存在较大局限性,预测精度有待进一步提高.本文基于闸坡站长时间(1959～2011年)月均验潮序列,结合集合经验模态分析(Ensemble Empirical Mode Decomposition,简称EEMD)与BP(Back Propagation)神经网络方法,提出一种改进的区域海平面变化趋势预测方法——EEMD-BP建模.本研究首先利用EEMD方法对原始序列进行分解,根据验潮序列中隐含的各个信号的不同频谱特征生成多个本征模函数(Intrinsic Mode Function,简称IMF),达到将时间序列平稳化,提高信噪比的效果.然后由各IMF作为BP神经网络的输入因子,分别预测各IMF的未来变化趋势,最后将输出结果重建得到原始序列的预测值.结果显示,EEMD能有效提取序列中隐含的多时间尺度信号,神经网络能较好地预测海平面未来变化趋势,相对于直接使用BP神经网络进行海平面变化时间序列预测(R=0.76,RMSE=36.74mm,ME=-3.46),EEMD-BP建模预测精度有显著提高(R=0.89,RMSE=28.16mm,ME=2.31).说明EEMD-BP建模首先对非平稳非线性时间序列进行平稳化、降噪等处理,再分别对分解后序列进行预测,有利于提高预测精度.该方法为相关区域海平面变化趋势预测研究提供现实参考意义.     

Enhancement of particulate organic carbon export flux induced by atmospheric forcing in the subtropical oligotrophic northwest Pacific Ocean

The effects of extreme atmospheric forcing on the export flux of particulate organic carbon (POC) in the warm oligotrophic nitrogen-limited northwest Pacific Ocean were examined in 2007 during the spring Asian dust storm period. Several strong northeast monsoon events (maximum sustained wind speeds approaching 16.7 m s^? 1, and gusts up to 19.0 m s^? 1) accompanied by dust storms occurred during a 1-month period. The cold stormy events decreased surface water temperature and induced strong wind-driven vertical mixing of the water column, resulting in nutrient entrainment into the mixed layer from subsurface waters. As a result, the export flux of POC ranged from 49 to 98 (average value = 71 ± 16) mg m^? 2 day^? 1, approximately 2–3 times greater than average values in other seasons. As dry and wet deposition of nitrogen attributable to Asian dust storm events does not account for the associated increases in POC stocks in this N-limited oligotrophic oceanic region, the enhancement of POC flux must have been caused by nutrient entrainment from subsurface waters because of the high winds accompanying the dust storm events.     

Tidal Asymmetry Changes in a Shallow Mud Estuary by a Restoration Project

The tidal asymmetry-induced siltation below tidal barriers is a worldwide problem that restricts regional socio-economic and environmental development. The hydrodynamic processes of the small mud estuary also feature a high uncertainty after estuary restoration measures. In this study, a hydrodynamic model based on the MIKE21 is used to quantify the responses of tidal asymmetry to a two-phase restoration project in Shuanglong Estuary, Bohai Bay, China. According to the numerical modeling results, the tidal flat removal in the upper estuary(first-phase restoration) induces the flood asymmetry switching to the ebb asymmetry in unrestored reach but enhances flood asymmetry in widening restored reach. Although the tidal asymmetry reverts to flood-dominated pattern after full restoration over the estuary, the imbalance between flood and ebb velocities is relieved. A possible net sediment transport pattern based on a comparison of dominant asymmetric current and actual sediment transport period shows net sediments in the upper estuary and inlet transport seaward and landward, respectively, in the first-phase restoration, whereas landward net sediment transport occurs in the whole estuary under the second-phase restoration scenario. Given these results, we assume that a switch from the flood-dominated estuary to ebb-dominated estuary can be caused by redesigning the cross-sectional profile. The quantitative comparison of Lagrangian residual currents also implies that a channel–shoal structure rather than a flat bathymetry can promote the mass transport. Therefore, reshaping the channel–tidal flat system in restoration projects can prevent the sedimentation of the estuary and improve the water environment.