基于HLA的数据记录联邦成员的设计与实现

具体分析了基于HLA的仿真系统采用数据记录的二种方式的优缺点,通过引入"快照"概念,在内存中管理数据,并提出一种内存分组存储机制优化采用集中式开发基于HLA的数据记录联邦成员。对于联邦成员实现的关键技术进行了详细论述。运行表明,该联邦成员能够满足仿真系统不间断、持续记录数据的要求。     

采伐影响下人工林木材生产与固碳功能权衡特征——以湖南会同森林生态实验站为例

中国人工林面积居世界首位,在全球气候变暖背景下,人工林在提供木材和固定CO₂等方面同时具有重要意义。然而木材生产与碳储量之间存在此消彼长的权衡关系,如何综合考虑二者权衡过程,实现区域森林综合效益最大化,是中国森林生态建设中亟待解决的问题。选择会同森林生态实验站磨哨林场作为研究区,采用人工林固定样地多年观测数据以及InVEST模型,定量评估木材生产与碳储量,构建了不同管理模式下的权衡分析方法,提出了研究区森林生态系统综合效益最佳的权衡对策。研究发现：① 在采伐活动的影响下,木材生产与碳储量显著负相关（R = -0.907, P < 0.001）,表现出强权衡关系;② 随着采伐强度增加,木材生产与碳储量的综合效益逐渐增加,权衡值先下降后上升;每10年采伐总面积10%~20%的管理模式下,收获木材量和碳储量的综合效益相对较高且权衡值最低,是最佳森林管理模式;③ 研究区当前采伐强度略高于最佳采伐强度,适当降低采伐强度能够使森林获取更多的综合效益。因此,在明确森林管理目标的基础上,可借助基于标准差的权衡分析方法,提出中国南方人工林生态系统服务提升与可持续经营的权衡对策。     

开封黄泛地层全新世中晚期碳密度和碳储量研究

开封古城相对完整的黄泛沉积序列为探索历史时期碳密度及储量提供了难得的研究载体。以开封城区（师专、医专和明伦）和郊区（金明）4个25 m岩芯为研究对象,通过对861个岩芯样品的容重、有机碳和黑碳分析测试,开展地层有机碳和黑碳密度及储量分析。结果表明：地层有机碳和黑碳含量垂直分布特征基本一致,高值主要集中在地表1 m范围内,其次是各朝代文化层附近,城区地层含量明显高于郊区。地层0~25 m黑碳密度均值为24.67 kg/m²,黑碳储量为11.30 Tg,分别占总有机碳密度和储量的24.26%和21.75%。表明地层黑碳碳库在总有机碳库中占有较大比例,在计算土壤或沉积物碳密度和碳储量时,应将黑碳也考虑在内。老城区0~25 m地层黑碳储量占比高出新区10%以上,主要与老城区受历朝人类活动影响强度较大及煤炭的广泛使用有关。研究结果可为寻找“遗失的碳”、精确计算碳循环和平衡提供参考。     

ALLUVIAL CHARACTERISTICS,GROUNDWATER–SURFACE WATER EXCHANGE AND HYDROLOGICAL RETENTION IN HEADWATER STREAMS

Conservative solute injections were conducted in three first-order montane streams of different geological composition to assess the influence of parent lithology and alluvial characteristics on the hydrological retention of nutrients. Three study sites were established: (1) Aspen Creek, in a sandstone–siltstone catchment with a fine-grained alluvium of low hydraulic conductivity (1·3×10⁻⁴ cm/s), (2) Rio Calaveras, which flows through volcanic tuff with alluvium of intermediate grain size and hydraulic conductivity (1·2×10⁻³ cm/s), and (3) Gallina Creek, located in a granite/gneiss catchment of coarse, poorly sorted alluvium with high hydraulic conductivity (4·1×10⁻³ cm/s). All sites were instrumented with networks of shallow groundwater wells to monitor interstitial solute transport. The rate and extent of groundwater–surface water exchange, determined by the solute response in wells, increased with increasing hydraulic conductivity. The direction of surface water–groundwater interaction within a stream was related to local variation in vertical and horizontal hydraulic gradients. Experimental tracer responses in the surface stream were simulated with a one-dimensional solute transport model with inflow and storage components (OTIS). Model-derived measures of hydrological retention showed a corresponding increase with increasing hydraulic conductivity. To assess the temporal variability of hydrological retention, solute injection experiments were conducted in Gallina Creek under four seasonal flow regimes during which surface discharge ranged from baseflow (0·75 l/s in October) to high (75 l/s during spring snowmelt). Model-derived hydrological retention decreased with increasing discharge. The results of our intersite comparison suggest that hydrological retention is strongly influenced by the geologic setting and alluvial characteristics of the stream catchment. Temporal variation in hydrological retention at Gallina Creek is related to seasonal changes in discharge, highlighting the need for temporal resolution in studies of the dynamics of surface water–groundwater interactions in stream ecosystems. © 1997 by John Wiley & Sons, Ltd.     

Discharge and water table predictions using a generalised TOPMODEL formulation

A simple, generalized saturated zone formulation is presented in this paper to relax the assumption of an exponential function originally made in TOPMODEL. This saturated zone model is based on the concept of a ‘discharge:relative storage’ (QΔS) function which is derived empirically, using recession curve analysis, and may be of arbitrary form. The generalized formulation is applied to the Seternbekken MINIFELT catchment in Norway, where detailed distributed water table data have been measured. These water table data are used to suggest an empirical, power law modification of the topographic a/tan β index. Results for the simulation through time of discharges and water table depths at a few locations show that the generalized saturated zone formulation is as efficient a simulator of the observed data as a conventional TOPMODEL, but requires one parameter less to be calibrated. The simulation of detailed water table distributions is only approximate in both cases. The modified power law index shows only a small improvement but provides a basis for a discussion of possible sources of error in the TOPMODEL assumptions for this site. © 1997 John Wiley & Sons, Ltd.     

Late quaternary sediment budget in alluvial-fan–source-basin systems in Japan

Sediment budgets since the Late-glacial were constructed for five alluvial-fan–source-basin systems in Japan. The Late-glacial and Holocene sediment yield from each source area was estimated based on digital elevation data and the morphometric analyses of geomorphological maps, in which all hillslopes and fluvial surfaces were classified. Late-glacial and Holocene sediment storage in each fan was calculated from stratigraphical data. The results have revealed that the ratio of sediment storage in a fan to sediment supply is between ca. 0.3 and 0.8. Such high ratios of sediment storage over long time periods cast doubt on the previously proposed steady-state theory of alluvial fan development. The storage ratio decreases if fan sediments are removed by neighbouring large rivers. The maximum storage ratio of 0.8 reflects the ratio of washload to total load for Japanese mountain rivers. © 1997 John Wiley & Sons, Ltd.     

Evaluation of CADISSE a regional storage capacity model

In this paper the validity of CADISSE, a regional storage capacity model developed to assess the sensitivity of catchment hydrology to climate variability, is examined. In CADISSE, catchment discharge sensitivity is expressed as the ratio of present maximum reservoir storage to catchment storage capacity. Present maximum storage should be interpreted as the maximum amount of water stored in a catchment at present. Catchment storage capacity is defined as the absolute amount of water that can be stored, given the catchment's dimensions and lithological characteristics. With CADISSE, catchment sensitivity can be quantified regionally using limited discharge data and topographic information. Furthermore, storage capacities can be assessed. CADISSE was successfully applied to 15 catchments in the Upper Loire Basin. However, successful application does not necessarily mean that the variables (present maximum storage and storage capacity) represent real world values. Therefore, a two‐step evaluation procedure is presented in this paper. To evaluate CADISSE, (1) the accurate assessment of regionally determined storage capacity, and (2) the importance of present maximum storage for catchment discharge sensitivity is examined with a daily discharge model by comparing observed and simulated catchment storage behaviour for dry and wet periods. The evaluation was carried out using the probability distributed daily discharge model, PDM, and a weather generator for three catchments with different storage capacities and storage behaviour. Results indicate that catchment storage capacity can be correctly quantified with CADISSE and that differences in storage behaviour are indeed important for analyses of catchment sensitivity. Hence, CADISSE has great potential as it can be used to identify flood‐ and drought‐prone catchments under present and future conditions. Copyright © 1999 John Wiley & Sons, Ltd.     

一种高性能的大区域遥感影像管理模型

在金字塔模型的基础上,应用一种能够快速提供多分辨率影像、具有高分布性能的大区域遥感影像管理模型———瓦片金字塔模型,并给出了模型的相关数据结构。该模型支持大区域遥感影像、瓦片独立压缩和分布式存储。分析显示:对于不同大小的遥感影像,模型都能提供一致的服务性能。     

张村河蓄水构筑物的多功能设计概念

以张村河堤岸整治工程为例,介绍了河道内蓄水构筑物的蓄水、溢流、美化及防洪等功能的创意设计,形成了人与自然和谐相处的环境体系;水工模拟试验结果表明,蓄水构筑物建成后能满足50年一遇洪水的防洪要求,小流量时,基本实现了蓄水建筑物间水面相连、过流动感和美学效果。张村河蓄水构筑物多功能设计概念将对北方间歇性城市河流综合整治工程具有重要的参考价值。     

SPATIAL AND TEMPORAL VARIABILITY OF SOIL SURFACE ROUGHNESS AND THE APPLICATION IN HYDROLOGICAL AND SOIL EROSION MODELLING

Accurate estimations of water retention and detention are needed to simulate surface runoff and soil erosion following a rainfall event in a catchment. Several equations to estimate the amount of surface depressional storage, the fraction of the soil surface covered by water and the amount of rainfall excess needed to start surface runoff have been developed by Onstad (1984). The random roughness and slope gradient are needed for those estimations. Surface micro-elevation data have been gathered by a photographic method. The random roughness was determined from those elevation measurements. Several factors which have an impact on the soil surface roughness were taken into account. The main sources of influence are the type of land use, the crop stage within the growing period and tillage direction. Analyses of variance indicated that the variation in the RR-index could be explained mainly by type of land use, orientation and field type. The temporal variation was relatively small. Gradient data have been determined from a digital elevation model, constructed by digitizing contours. Combining the random roughness and the steepness of slope, the amounts of surface water retention and detention could be estimated. Knowledge of water retention and detention will improve the estimations of runoff and soil erosion modelling in catchments, such as those made with the LISEM model. The agricultural systems examined in this study have similar random roughness values in summer. Different soil erosion rates for several types of land use can not therefore be explained by the random roughness.