Capturing the essential spatial variability in distributed hydrological modelling: Infiltration parameters

Selecting the correct resolution in distributed hydrological modelling at the watershed scale is essential in reducing scale-related errors. The work presented herein uses information content (entropy) to identify the resolution which captures the essential variability, at the watershed scale, of the infiltration parameters in the Green and Ampt infiltration equation. A soil map of the Little Washita watershed in south-west Oklahoma, USA was used to investigate the effects of grid cell resolution on the distributed modelling of infiltration. Soil-derived parameters and infiltration exhibit decreased entropy as resolutions become coarser. This is reflected in a decrease in the maximum entropy value for the reclassified/derived parameters vis a vis the original data. Moreover, the entropy curve, when plotted against resolution, shows two distinct segments: a constant section where no entropy was lost with decreasing resolution and another part which is characterized by a sharp decrease in entropy after a critical resolution of 1209 m is reached. This methodology offers a technique for assessing the largest cell size that captures the spatial variability of infiltration parameters for a particular basin. A geographical information system (GIS) based rainfall-runoff model is used to simulate storm hydrographs using infiltration parameter maps at different resolutions as inputs. Model results up to the critical resolution are reproducible and errors are small. However, at resolutions beyond the critical resolution the results are erratic with large errors. A major finding of this study is that a large resolution (1209 m for this basin) yields reproducible model results. When modelling a river basin using a distributed model, the resolution (grid cell size) can drastically affect the model results and calibration. The error structure attributable to grid cell resolution using entropy as a spatial variability measure is shown.     

利用黄河泥沙围出“渤海湖”的初步设想

本文是一个关于将渤海变成淡水湖的水利工程的构想。让黄河的大量泥沙通过人工导流的方式沿莱州湾南岸与渤海海峡沉积延伸,产生的陆地将渤海封闭并逐渐形成淡水湖。这一工程将陆地连接山东半岛与辽东半岛,并为华北提供巨大淡水库,具有显著的经济、生态效益。具体实施上,可通过两道渔网式围栏促使黄河泥沙定点沉积并阻挡浪潮侵蚀,通过加强汛期水量增加黄河口泥沙。     

Response characteristics of plunge pool slabs of Xiaxiluodu Hydropower Station to flood discharge pulsating-pressure under valley deformation conditions

The key problem of the energy dissipation scheme of the arch dam body flood discharge and plunge pool below the dam is the stability problem of the plunge pool slab. As the protection structure of the underwater bed, the plunge pool slab bears the continuous impact of high-speed water flow. The hourly average dynamic water pressure on the slab is one of the main loads directly affecting the stability of the slab and is the main factor causing its erosion destruction. After the impoundment of the Xiluodu Hydropower Station, the measuring line of valley width in the plunge pool area has been continuously shrinking. By 2020, the cumulative shrinking value is about 80 ​mm. In light of the general background condition of valley shrinkage, daily inspection, annual detailed inspection, underwater inspection and drainage inspection of the plunge pool found that the plunge pool has experienced different degrees of damage, which greatly influences the long-term safety stability of the plunge pool. In this paper, the prototype observation data of flood discharge is used as the input load of pulsating-pressure, and the stress and displacement distribution of the plunge pool structure under the vibration load of flood discharge is analyzed under the condition that the stress and strain state of the plunge pool is changed under the influence of valley displacement. The results show that the stress, strain, and displacement distribution of the plunge pool are mainly caused by valley deformation, the vibration caused by flood discharge is little in influence, and the impact effect of deep hole flood discharge tongue on the plunge pool slab is weak.     

1965—2014年黑龙江省洪涝灾害时空演变特征

基于1965—2014年黑龙江省63个气象站逐月降水资料,利用Z指数、区域洪涝指数、数理统计和反距离权重插值等方法,得出洪涝等级（轻涝、中涝、重涝）,分析近50年黑龙江省不同等级洪涝灾害时空分布特征及其变化趋势。结果表明,近50年黑龙江省发生区域性轻度、中度和重度洪涝灾害分别为7次、7次和6次,降水倾向率为0.864 mm/a;洪涝灾害发生频率分布不均,发生轻涝104次、中涝74次以及重涝29次,洪涝灾害发生频率较高地区逐年扩大;同时,发生洪涝灾害的站数比差异明显,且随时间呈缓慢上升趋势,其中,轻涝、中涝和重涝站数比的增幅分别为1.3/10a、1.6/10a和0.85/10a;洪涝灾害高发期主要在20世纪80年代、90年代和2010年之后,主洪涝区为鹤岗、伊春、黑河和牡丹江地区,次洪涝区为大兴安岭和大庆地区。     

吉林省主汛期典型多雨年和少雨年成因对比分析

将1951-2011年吉林省主汛期降水量排名的前、后6位分别定义为多、少雨年,利用NCEP（2.5°×2.5°）再分析资料计算主汛期平均高度场、温度场、风场及比湿、涡度等物理量场;根据天气学原理和常规天气预报经验,对比分析主汛期典型多雨与少雨天气系统结构形态、分布位置、中心强度等特征。结果表明：500 hPa多雨年568等高线较少雨年平均偏南3个纬度,副热带高压588等高线较少雨年平均偏西7个经度偏北1个纬度;低层辐合高层辐散是多雨年的重要特征;850 hPa和700 hPa平均水汽含量多雨年明显多于少雨年;典型多雨年850 hPa风场贝加尔湖附近为单辐合中心,少雨年为双辐合中心。     

DCMT活动光栅控制系统

ＤＣＭＴ活动光栅的控制系统是主测微器的主要部分，本控制系统操作灵活，它既能联机工作又能脱机工作，并具有自动报警和自动复位功能。主测微器承担测定天体和５个自准直像的位置，要比传统的活动光栅复杂得多．本设计的独特之处在于用分区、分时并配以光栏控制诸方法确定全部像的位置。保证了所有的观测在同一个系统之内．经一年来的实际观测证明，本系统精度优于０”．０３，达到了同类别微器的先进水平．     

构造地质学中的地质思维初探

地质模型的建立,地质思维的正确运用已成为引导地质学前进的两个关键环节。本文以构造地质学领域中近年来的研究成果为基础,探讨了与空间和时间有关的地质思维问题。指出:一个地质现象的观察,一定要结合高一级尺度和低一级尺度的综合研究,才能得出既有形成机制、又有组合规律的全面结论;一个构造形迹,一定要尽力区分出不同的递进变形阶段,以提供以时间为坐标的演化序列。文末,笔者提供了两个研究实例,一个用小构造分析论证区域构造演化,一个据叠加变形原理,把研究对象区分成不同的区段和亚域。     

东川拖布卡金矿矿化层位与找金方向

超大型拖布卡金矿的发现,表明东川地区具备找金前景.“黑层”是金的成矿前提,断裂加蚀变是成矿必备条件,基性与中性岩脉在容矿层中的侵位,是找富金的重要标志.金成矿全过程应是多旋回（晋宁、华力西、燕山、喜马拉雅山）成矿作用,且受剪切破碎带控制的黑层型金矿.     

Flood pattern and weather determine Populus leaf litter breakdown and nitrogen dynamics on a cold desert floodplain

Patterns and processes involved in litter breakdown on desert river floodplains are not well understood. We used leafpacks containing Fremont cottonwood (Populus deltoides subsp. wislizenii) leaf litter to investigate the roles of weather and microclimate, flooding (immersion), and macroinvertebrates on litter organic matter (OM) and nitrogen (N) loss on a floodplain in a cool-temperate semi-arid environment (Yampa River, northwestern Colorado, USA). Total mass of N in fresh autumn litter fell by 20% over winter and spring, but in most cases there was no further N loss prior to termination of the study after 653 days exposure, including up to 20 days immersion during the spring flood pulse. Final OM mass was 10–40% of initial values. The pattern of OM and N losses suggested most N would be released outside the flood season, when retention within the floodplain would be likely. The exclusion of macroinvertebrates modestly reduced the rate of OM loss (by about 10%) but had no effect on N dynamics over nine months. Immersion in floodwater accelerated OM loss, but modest variation in litter quality did not affect the breakdown rate. These results are consistent with the concept that decomposition on desert floodplains progresses much as does litter processing in desert uplands, but with periodic bouts of processing typical of aquatic environments when litter is inundated by floodwaters. The strong dependence of litter breakdown rate on weather and floods means that climate change or river flow management can easily disrupt floodplain nutrient dynamics.     

土地利用现状图中数据缩编的质量控制分析

1∶50000土地利用现状图是土地利用研究的基础数据之一,编制土地利用现状图对制定河南省社会和经济中长期发展规划、土地利用总体规划和城乡规划,全面加强土地管理,促进全省经济发展起着非常重要的作用.本文结合1∶50000土地利用现状要素数据缩编工程质量检查工作实践,总结了质量检查的内容、技术要求及检查方法,提高了作业质量和效率.