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11.
APPLICATION OF GEOGRAPHICAL PARAMETER DATABASE TO ESTABLISHMENT OF UNIT POPULATION DATABASE 总被引:1,自引:1,他引:0
Now GIS is turning into a good tool in handling geographical, economical, and population data, so we can obtain more and more information from these data. On the other hand, in some cases, for a calamity, such as hurricane, earthquake, flood, drought etc., or a decision-making, such as setting up a broadcasting transmitter, building a chemical plant etc., we have to evaluate the total population in the region influenced by a calamity or a project. In this paper, a method is put forward to evaluate the population in such special region. Through exploring the correlation of geographical parameters and the distribution of people in the same region by means of quantitative analysis and qualitative analysis, unit population database (1km× 1km) is established. In this way, estimating the number of people in a special region is capable by adding up the population in every grid involved in this region boundary. The geographical parameters are obtained from topographic database and DEM database on the scale of 相似文献
12.
Wang Yanhui 《水文研究》1992,6(2):241-251
Black locust (Robina pseudoacacia) has become one of the most important shelter species in the loess area of northwest China. This paper summarizes recent research concerning its hydrological influence, including canopy interception, litter absorption capacity, its effect on rainfall kinetic energy, infiltration rates, surface runoff, soil moisture, and evapotranspiration, and its role in soil conservation. Several predictive models are listed. on the basis of existing results, optimum characteristics for an effective plantation are defined, and problems requiring further research are identified. 相似文献
13.
Aimed at promoting regional coalitions and expanding the approach to economic links, this paper puts forward some new concepts
such as link intensity and receiving coefficient, expounds the indexes of quantitative analysis of economic links and establishes
the quantitative-analysis model of economic links. With help of the model, this paper calculates the values of the link intensities
between Su-Xi-Chang (Suzhou-Wuxi-Changzhou) region and Shanghai, and analyzes the regional difference of the economic links. 相似文献
14.
本文作者利用IOS近似模型,计算了星际分子云条件下A型CH3CN-H2含超精细能级的碰撞跃迁速率系数。温度范围是20K-140K。为研究分子云与恒星形成区的物理、化学性质提供了有用的基础分子数据。 相似文献
15.
Continuous wavelet analyses of hourly time series of air temperature, stream discharge, and precipitation are used to compare the seasonal and inter‐annual variability in hydrological regimes of the two principal streams feeding Bow Lake, Banff National Park, Alberta: the glacial stream draining the Wapta Icefields, and the snowmelt‐fed Bow River. The goal is to understand how water sources and flow routing differ between the two catchments. Wavelet spectra and cross‐wavelet spectra were determined for air temperature and discharge from the two streams for summers (June–September) 1997–2000, and for rainfall and discharge for the summers of 1999 and 2000. The diurnal signal of the glacial runoff was orders of magnitude higher in 1998 than in other years, indicating that significant ice exposure and the development of channelized glacial drainage occurred as a result of the 1997–98 El Niño conditions. Early retreat of the snowpack in 1997 and 1998 led to a significant summer‐long input of melt runoff from a small area of ice cover in the Bow River catchment; but such inputs were not apparent in 1999 and 2000, when snow cover was more extensive. Rainfall had a stronger influence on runoff and followed quicker flow paths in the Bow River catchment than in the glacial catchment. Snowpack thickness and catchment size were the primary controls on the phase relationship between temperature and discharge at diurnal time scales. Wavelet analysis is a fast and effective means to characterize runoff, temperature, and precipitation regimes and their interrelationships and inter‐annual variability. The technique is effective at identifying inter‐annual and seasonal changes in the relative contributions of different water sources to runoff, and changes in the time required for routing of diurnal meltwater pulses through a catchment. However, it is less effective at identifying changes/differences in the type of the flow routing (e.g. overland flow versus through flow) between or within catchments. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
16.
The uptake and release of trace metals (Cu, Ni, Zn, Cd, and Co) in estuaries are studied using river and sea end-member waters
and suspended particulate matter (SPM) collected from the Changjiang Estuary, China. The kinetics of adsorption and desorption
were studied in terms of environmental factors (pH, SPM loading, and salinity) and metal concentrations. The uptake of the
metals studied onto SPM occurred mostly within 10 h and reached an asymptotic value within 40 h in the Changjiang Estuary.
As low pH river water flows into the high pH seawater and the water become more alkaline as it approaches to the seaside of
estuary, metals adsorb more on SPM in higher pH water, thus, particulate phase transport of metal become increasingly important
in the seaward side of the estuary. The percentage of adsorption recovery and the distribution coefficients for trace metals
remained to be relatively invariable and a significant reduction only occurred in very high concentrations of metals (>0.1 mg L−1). The general effect of salinity on metal behavior was to decrease the degree of adsorption of Cu, Zn, Cd, Co, and Ni onto
SPM but to increase their adsorption equilibrium pH. The adsorption–desorption kinetics of trace metals were further investigated
using Kurbatov adsorption model. The model appears to be most useful for the metals showing the conservative behavior during
mixing of river and seawater in the estuary. Our work demonstrates that dissolved concentration of trace metals in estuary
can be modeled based on the metal concentration in SPM, pH and salinity using a Kurbatov adsorption model assuming the natural
SPM as a simple surfaced molecule. 相似文献
17.
Glacier change and glacier runoff variation in the Tuotuo River basin,the source region of Yangtze River in western China 总被引:3,自引:0,他引:3
Glaciers in the Tuotuo River basin, western China, have been monitored in recent decades by applying topographical maps and
high-resolution satellite images. Results indicate that most of glaciers in the Tuotuo River basin have retreated in the period
from 1968/1971 to 2001/2002, and their shrinkage area is 3.2% of the total area in the late 1960s. To assess the influence
of glacier runoff on river runoff, a modified degree–day model including potential clear-sky direct solar radiation has been
applied to the glaciated regions of the river basin over the period 1961–2004. It was found that glacier runoff has increased
in the last 44 years, especially in the 1990s when a two-thirds increase in river runoff was derived from the increase in
glacier runoff caused by loss of ice mass in the entire Tuotuo River basin. 相似文献
18.
19.
Imaging of Buried Archaeological Materials: The Reflection Properties of Archaeological Wood 总被引:1,自引:0,他引:1
Stephanie H.L. Arnott Justin K. Dix Angus I. Best David J. Gregory 《Marine Geophysical Researches》2005,26(2-4):135-144
Effective marine archaeological site management demands detailed information on not only the spatial distribution of artefacts
but also the degradation state of the materials present. Although sonar methods have frequently been used in an attempt to
detect buried wooden shipwrecks they are currently unable to indicate their degradation state. To assess the sensitivity of
acoustic measurements to changes in the degradation state of such material, and hence the potential for sonars to quantify
degradation, laboratory measurements of compressional wave velocity, as well as bulk density for oak and pine samples, in
varying states of decay, were undertaken. These data enabled the calculation of theoretical reflection coefficients for such
materials buried in various marine sediments. As wood degrades, the reflection coefficients become more negative, resulting
in the hypothesis that the more degraded wood becomes, the easier it should be to detect. Typical reflection coefficients
of the order of −0.43 and −0.52 for the most degraded oak and pine samples in sand are predicted. Conversely, for wood exposed
to seawater the predicted reflection coefficients are large and positive for undegraded material (0.35 for oak, 0.18 for pine)
and decrease to zero or slightly below for the most degraded samples. This indicates that exposed timbers, when heavily degraded,
can be acoustically transparent and so undetectable by acoustic methods. Corroboration of these experimental results was provided
through comparison with high resolution seismic reflection data that has been acquired over two shipwrecks. 相似文献
20.
Surface waves are the roughness element of the ocean surface. The parameterization of the drag coefficient of the ocean surface is simplified by referencing to wind speed at an elevation proportional to the characteristic wavelength. The dynamic roughness is analytically related to the drag coefficient. Under the assumption of fetch limited wave growth condition, various empirical functions of the dynamic roughness can be converted to equivalent expressions for comparison. For datasets covering a wide range of the dimensionless frequency (inverse wave age), it is important to account for the variable rate of wave development at different wave ages. As a result, the dependence of the Charnock parameter on wave age is nonmonotonic. Finally, the analysis presented here suggests that the significant wave steepness is a sensitive property of the ocean surface and a single variable normalization of the dynamic roughness using a wavelength or wave height parameter actually produces more robust functions than bi-variable normalizations using wave height and wave slope. 相似文献