Table of Content

25 September 2003, Volume 58 Issue 5 Previous Issue    Next Issue

Discussion on the Index Method of Regional Land Use Change ZHU Huiyi, LI Xiubin 2003, 58 (5):  643-650.  doi: 10.11821/xb200305001 Abstract ( )   PDF (983KB) ( )   Save Recently, many sorts of index models have been widely adopted in the analysis of land use change in China. And they do play an important role in summarizing the rule of regional land use changes. However, according to the present research papers, there are some confusions and misuses in their applications, which root in faultiness, abnormity and misunderstanding of the indices or index calculation. By detailed exploration of the indices embedded in research materials, three classifications are identified on the basis of their application purposes: the change of regional land resources (change rate index and level change index), the direction of land use change (transition matrix and flow direction rate) and the spatial pattern of land use change (dynamic degree, relative change rate, adjacency degree, barycenter, frequency degree and importance degree). Then all the indices listed above are discussed under the purposed framework, including their concepts, calculation methods, application fields, misuses, and some application suggestions. This paper also gives a remark in the end that the research of land use change needs new breakthroughs in both theory and methodology. Index method is only a simple kind with limited functions, and much more efforts should be devoted to integrative, predictive methods in the coming days. References | Related Articles | Metrics

The Temporal-spatial Characteristics of Rural Residential Land in China in the 1990s TIAN Guangjin, LIU Jiyuan, ZHUANG Dafang 2003, 58 (5):  651-658.  doi: 10.11821/xb200305002 Abstract ( )   PDF (1006KB) ( )   Save According to statistics of the rural land vector datasets on the scale of 1:100000, rural residential land in China increased by 7.88×105 hm2 in the 1990s. Rural residential land expanded more rapidly during the first five years, which took up 70.3% of that of the 1990s and slowly during the latter five years, being 29.7%. In order to compare the spatial pattern of rural expansion in the two periods, the rural residential land zoning is completed using CA (cellular automata) and ANN (artificial neural network). Rural land percentage, morphology, slope and neighborhood index are used to build the bottom-top zoning model. The paper studies the temporal-spatial characteristics of rural residential land in China. (1) During 1990-1995, rural residential land expanded dramatically in the Yangtze River Delta, Pearl River Delta and North China Plain. It increased most rapidly in the Pearl River and Yangtze River deltas, being 28.11% and 24.31% respectively or 72.34% of the total rural expansion in China during 1990-1995. (2) During 1996-2000 the rural expansion in eastern coastal area slowed down but speeded up in the western area. The rural expansion in the Yangtze River Delta, Pearl River Delta and North China Plain was 35.44%. The other coastal areas fell to 1.45%. (3) In central area the rural land expansion took up 4.47% of the country's total while it expanded a little rapidly during the first five years (6.64%) although it slowed down in the latter five years. Rural land expansion slowed down in the eastern part of North China in the 1990s. (4) Rural land expanded slowly in the first five years (14.5% of the country's total) while it increased in the latter five years in western area (increased to 56.26%). Rural land increased more rapidly in the Sichuan Basin. During the first five years, it was slower than the coastal area. With the economic development and the loose control on cropland of the western area, the rural land expanded more rapidly. References | Related Articles | Metrics

Landuse Changes and Its Implication to the Ecological Consequences in Lower Yangtze Region LI Xiaowen, , FANG Jingyun, PIAO Shilong 2003, 58 (5):  659-667.  doi: 10.11821/xb200305003 Abstract ( )   PDF (1301KB) ( )   Save Based on the multi-temporal remotely sensed data of TM, this research attempted to reveal the spatio-temporal trends in landuse and landcover in Lower Yangtze Region by depicting and analyzing the process and spatial heterogeneity of landuse & landcover changes in the region, especially placing emphasis on the transformation modes and spatial behavior of landuse. In order to achieve the goal, the magnitude and spatial distribution of landuse transformation from the 1988 to the 1998 were analyzed by the transformation matrixes and the spatial layouts of landuse, then changes of landuse degree and associated traits in spatial distribution were targeted by establishing and applying the landuse index. Furthermore, the spatial shifting of landuse transformation intensity was studied by conceiving and using Landuse Transformation Index. As a hot topic, the loss of cultivated land and its driving force were also included in this step, and the top ten significant forms of landuse transformation were analyzed, in particular the trends in spatial transformation according to their Important Value individually. References | Related Articles | Metrics

Study on Spatial Optimization Allocation of Land Use in the Typical Red Soil Hilly Region in South China ZHANG Hongqi, LI Jiayong, NIU Dong 2003, 58 (5):  668-676.  doi: 10.11821/xb200305004 Abstract ( )   PDF (1418KB) ( )   Save On the basis of the analysis of land use structure, land suitability evaluation, experimental data of Qianyanzhou Station and the household investigation data, the methodology and technique based on a linear programming model in combination with GIS is applied to a case study for spatially optimal allocation of land resource with definite quantity and quality in Qianyanzhou. The conclusions are as follows: (1) Despite the progress made in agriculture through land use structure change in red soil region, the proportion of artificial grassland is very low and the use of natural grassland is inefficient, which leads to the secular stagnation of herbivorous animal husbandry. (2) The optimal scenario results can be produced by a linear programming model, which is based on a set of technical coefficients structured in an objective function and a set of constraints to be provided by GIS. (3) The optimal scenario results show that the structure of grain-horticulture-forestry in the presented scenario has been converted to the structure of grain-horticulture-animal husbandry-forestry in the optimal scenario. References | Related Articles | Metrics

Coupling Relationship Between Land Use Change and Industrialization & Urbanization in the Zhujiang River Delta ZHANG Wenzhong, WANG Chuansheng, LV Xin, FAN Jie 2003, 58 (5):  677-685.  doi: 10.11821/xb200305005 Abstract ( )   PDF (1208KB) ( )   Save This paper focuses on the corresponding type of land use to different stages and state of industrialization and urbanization respectively and the regularity between them. Firstly, the data of land use in the Zhujiang River Delta from 1990 to 2000 are processed. Secondly, we get the composite coefficient of land use in the Delta. According to the value of Lc, we put the land use into 4 types. Thirdly, we try to determine the types of land use using the coupling coefficients of the output value of second industry and tertiary industry to GDP and the urbanization with land use respectively (LIc & LUc). And we can see that the two coupling coefficients and land use composite coefficient show a strong consistency through a comparison, i.e., when LIc < 0.10, the land use belongs to the steady type; when 0.10 < LIc < 1.00, the land use belongs to the comparatively steady type; when 1.00 < LIc < 10.0, the land use mainly belongs to the slow change type and drastic change type; when LIc > 10.0, the land use often belongs to the drastic change type and slow change type. And when LUc < 0.01, the land use is of steady type; when 0.01 < LUc < 0.30, the land use is of the comparatively steady type, when 0.30 < LUc < 1.00, of the slow change type and drastic change type; and when LUc >1.00, the land use is mainly the drastic change type and slow change type. References | Related Articles | Metrics

Comparative Study on Eco-geographic Regional Systems between China and USA WU Shaohong, YANG Qinye, ZHENG Du 2003, 58 (5):  686-694.  doi: 10.11821/xb200305006 Abstract ( )   PDF (1237KB) ( )   Save Eco-geographical region is a major ecosystem in geographic zonality. A hierarchical system, which is formed by division or combination of natural features based on geographic relativity and comparison of major ecosystem factors and geographic zonality, is called eco-geographic regional system. A comparison of the studies of this topic between Chinese and overseas scientists will enrich ideology of this field, facilitate academic exchange with understandable scientific language and introduce China's progress to the world. The authors compared both China's and overseas eco-geographic regional systems in development process, hierarchical units, delineating criteria, mapping procedures and regions. The results indicate that there are main common points in the subject, such as objectives, research contents and service objects connecting with environment, ecology and global change. Of the existing eco-regional systems, Robert G Bailey's systems of the United States, North America and the continent are comparatively close to China's system in hierarchical units, mapping procedure and regions. References | Related Articles | Metrics

Study on Models for Monitoring of Grassland Biomass around Qinghai Lake Assisted by Remote Sensing NIU Zhichun, NI Shaoxiang 2003, 58 (5):  695-702.  doi: 10.11821/xb200305007 Abstract ( )   PDF (973KB) ( )   Save Taking the region around the Qinghai Lake as the study area and using the Landsat Thematic Mapper data and the measured grass yield data, the monadic linear regression models and the non-linear regression models were established, respectively, to express the relations between grassland biomass and the vegetation indices. There are two types of sampling site, i.e., the larger one is 30 m×30 m and the smaller one is 1 m×1 m. Each larger sampling site includes one smaller one which was randomly selected. The major conclusions from this study are: 1) the fitting accuracies of the non-linear regression models are much higher than those of the non-linear regression models, namely, the results obtained from the non-linear regression models are more accordant with the measured grassland biomass data in comparison with those from the monadic linear regression models; 2) the comparison of different forms of the non-linear regression analysis on the relations between the vegetation indices and the measured grassland biomass data indicates that the cubic equation is the best one in terms of the suitability of use in the study area; 3) the results from the non-linear regression analysis show that the order is RVI, NDVI, SAVI, MSAVI and DVI in terms of the fitting accuracy between these vegetation indices and grassland biomass data; and 4) the non-linear model Y = -18.626RVI3+220.317RVI2-648.271RVI+691.093 is the best model which can be used in monitoring grassland biomass based on the vegetation indices in the region around the Qinghai Lake. References | Related Articles | Metrics

The Effects of Grassland Improvement on Terrestrial Ecosystem's Nutrients: A Case Study of Jian'ou Niukenglong Grassland Ecosystem Experimental Station ZHU Lianqi, XU Shuming, CHEN Peiyun 2003, 58 (5):  703-711.  doi: 10.11821/xb200305008 Abstract ( )   PDF (1139KB) ( )   Save This paper studies the effects of grassland improvement on distributions and circulations of nutrients in terrestrial ecosystems, taking Jian'ou Niukenglong Grassland Ecosystem Experimental Station as a case. During two years experiment, the land cover types had been transformed from desert slope-land to grasslands. The experimental results indicate that with the increase in vegetation coverage, the soil total concentrations of nitrogen, phosphorus, and potassium grow rapidly, but that of aluminum decreases obviously. The increases in the total concentrations of nitrogen, phosphorus, and potassium are mainly the consequences of changes of the factors affecting soil evolution, e.g., soil moisture, and changes of soil evolution processes, e.g., weathering rate and decrease of soil erosion. The changes are caused by land coverage growth during the processes of land cover change from desert slope-land to grassland. Conversely, with the change of the land cover types, the increase of land coverage, the activity of aluminum accelerated as well, the down-penetration and lateral penetration of aluminum have been strengthened. Therefore, the loss of aluminum within the experimental terrestrial ecosystem was inevitable, and the total concentration and content of aluminum in the soil have become smaller and smaller, though the growth of grass has been absorbing some amounts of aluminum. Land cover change also affects the circulations of nutrients in terrestrial ecosystem, for the purpose of study on nutrient circulations, we choose plant's absorption, litter and reservation of nutrients to establish the index to indicate the situations of nutrient circulations within terrestrial ecosystems. The results made it clear that in the two land cover types, i.e., two grassland ecosystems, the sequence of nutrient circulation indices are N＞K＞P＞Al in Chamaecrista rotundifolia (pers) green ＋ Pasalum thunbergii and P＞N＞K＞Al in Glycine max var. ＋ Pasalum thunbergii. On the basis of the study, we can conclude that land cover change affects both distributions and circulations in terrestrial ecosystems, different changes have distinct influences on distributions and circulations, and different nutrients are affected to varying degrees in some contents. References | Related Articles | Metrics

The Analysis of the Urban Climate in Chuxiong of Yunnan: Comparison of Urban Heat Island Effect in China HE Ping, LI Hongbo, SHU Jiong, LU Xiaoqin, SUN Juan 2003, 58 (5):  712-720.  doi: 10.11821/xb200305009 Abstract ( )   PDF (1244KB) ( )   Save Chuxiong is a medium-sized city on the Yunnan-Guizhou Plateau. The data (1959-2000) of Chuxiong and Nanhua observatories of Yunnan are compared in this paper. By Mexh wavelet analysis and comparison of the heat island effect of Chuxiong with Shanghai etc., the intensity of heat island for different cities has been examined. At the same time, the law for the annual and daily intensities of heat island in Chuxiong city has been found. The results indicate that the urban heat island effect of Chuxiong has become more and more obvious since the 1980s, with evident seasonal variations. The different variation laws are summarized by comparing the heat island effect of Chuxiong with Shanghai etc. The heat island effect is influenced by different backgrounds. It is revealed that with urban expansion of Chuxiong, the relative humidity and absolute humidity in Chuxiong have gradually reduced, and the effect of dry island has gradually appeared. The trend of dry island is intensifying in Chuxiong. References | Related Articles | Metrics

The Variability of Winter Monsoon Intensity in Xisha Waters, South China Sea for the Last More Than 50 Years PENG Zicheng, , CHEN Tegu, NIE Baofu, LIU Guijian, HE Jianfeng, CHENG Jiman 2003, 58 (5):  721-726.  doi: 10.11821/xb200305010 Abstract ( )   PDF (791KB) ( )   Save We have used correlative analysis between 1958-1997 mean December-January- February NE winter monsoon velocities, measured at the Yongxing Island Observatory, as a winter monsoon intensity index (WMI) and mean δ18O data for corresponding months from Porites lutea coral, collected in the northern part of the South China Sea, to obtain a linear equation: WMI (m/s) = -4.913-2.138δ18O (‰), r = 0.83, n = 40. The high correlative coefficient between the above-mentioned two series of WMI and δ18O data is made by using high-pass filtering method. On the basis of the calculated WMI sequence from 1944 to 1977, the interdecadal variability shows that the WMI series decreases in the 1940s-1960s, slightly increases in the 1970s, but decreases again in the 1980s-1990s. The interannual variability reveals that the WMI series decreases obviously from 1944 to 1977 with the correlative equation of WMI (m/s) = 79.69-0.0377 Year, r = 0.68, n = 54. The linear slope is negative, which means that the WMI series decreases by about 0.4 m/s every 10 years. The power-spectral analysis displays that a 54-year WMI series is provided with periodicity of a 2.5-7 year band, which is related to the QBO band of 2-2.4 years and ENSO band of 3-8 years. Therefore, it can be considered that the winter monsoon variability in the South China Sea is also controlled by the global change. References | Related Articles | Metrics

Impacts of Climate Change and Human Activities on Soil Carbon Storage in China ZHOU Tao, SHI Peijun, WANG Shaoqiang 2003, 58 (5):  727-734.  doi: 10.11821/xb200305011 Abstract ( )   PDF (929KB) ( )   Save More than 2000 soil samples obtained from the second soil census in China in the year 1998 were applied to analyse the correlations of soil organic carbon storage (SOC) and climatic factors, including annual mean temperature (T), and sum of precipitation (P). The results show that: (1) the correlations are quite different in different temperature zones. In the area where T ≤10oC, the correlation between SOC and temperature has the strongest negative correlation. In the area where 10oC < T ≤20oC, a positive correlation appears under the influence of precipitation. In the area where T > 20 oC, the correlation between SOC and temperature and precipitation is inadequate. (2) Due to the strong positive correlation between temperature and precipitation in China, the partial correlation method is thus better than Pearson correlation method. (3) The correlation between SOC and temperature and precipitation in cultured soil is weaker than that of non-cultured soil, which could attribute to human activities. (4) 26 pairs of soil samples, each pair coming from the same place which has the same soil properties and the same climatic condition, and consisting of one sample in cultured soil and the other in non-cultured soil, are used to analyse the difference of soil organic carbon storage between cultured and non-cultured soil. The results show that the differences of SOC are significant in two types of soils, and as a whole there is certain SOC released to the atmosphere as forest or grassland is converted to cropland. References | Related Articles | Metrics

Climate Change and Harvest in Xi'an since 1736: The High-resolution Data Derived from the Archives in the Qing Dynasty HAO Zhixin, ZHENG Jingyun, GE Quansheng 2003, 58 (5):  735-742.  doi: 10.11821/xb200305012 Abstract ( )   PDF (1057KB) ( )   Save Based on snow, rainfall and harvest archives records in the Qing Dynasty (1644-1911 AD), the modern meteorological observation data, the annual winter mean temperature and seasonal precipitation series from 1736 to 2000 and the series of harvest in summer and autumn from 1736 to 1910 are reconstructed. Meanwhile, the characteristics of climate change and the relationship between climate change and harvest are analyzed by using the high-resolution data. The results show: (1) Warm and cold changes in Xi'an have obvious inter-centennial fluctuation. Climate is relatively warm in the 18th century and cold in the 19th century, but turns warm with a rapid warming trend in the 20th century. (2) Precipitation changes have obvious inter-decadal fluctuation, experiencing six rainy periods and seven drought periods in Xi'an since 1736, in which the mean precipitation in the rainy periods is 16% more than that in drought periods. (3) The coefficients between the precipitation from June to August and the harvest in autumn are well correlated, and the precipitation during the period from September to May and the harvest in summer are remarkable. References | Related Articles | Metrics

Environmental Changes and Cultural Transition at 4 cal. ka BP in Central Gansu AN Chengbang, FENG Zhaodong, TANG Lingyu, CHEN Fahu 2003, 58 (5):  743-748.  doi: 10.11821/xb200305013 Abstract ( )   PDF (831KB) ( )   Save In Gansu Province, the thick, continuous accumulated loess makes a high-resolution climatic sequence available. Accompanied by abundant ancient cultural relics, all these make it an proper region for the study of the relationship between human adaptation and paleoenvironmental change. The Sujiawan and Dadiwan sections, located in the heartland of Gansu, are ideal places for further investigations on Holocene climatic variations and their impact on human activity. Both field observations and analytical results confirm the abrupt environmental change at 4 cal. ka BP. And all proxies present the same trend. Decreased organic matter content indicates low vegetation coverage. Increased grain size shows the weakening summer monsoon and accumulation of loess. Abundant snails were eliminated because of the deteriorated environment. This event around 4 cal. ka BP is ubiquitous in northern China. Before 4 cal. ka BP, Majiayao Culture (5.5-4.2 cal. ka BP) and Qijia Culture (4.2-3.9 cal. ka BP) were basically distributed in the Gansu-Qinghai region. In late Qijia Culture, agriculture in the Gansu-Qinghai region came down. Villages became small and sparse. Splendidly painted potteries were replaced by crude potteries. Funerary objects were absent, meanwhile, the prevalent porcine mandibles were replaced by sheep bones. This is a significant symbol of the cultural transition. In short, we strongly suggest that rapid environmental deterioration, identified by the abrupt fluctuation of all proxies at 4 cal. ka BP, caused the decline of agriculture and gave birth to the stockbreeding. References | Related Articles | Metrics

Sedimentary Dynamics and Geomorphic Evolution of the Laizhou Shoal WANG Qing, YANG Hua, ZHONG Shaoyun, DU Guoyun, ZHANG Yunji, GAO Guangchen 2003, 58 (5):  749-756.  doi: 10.11821/xb200305014 Abstract ( )   PDF (1201KB) ( )   Save Based on field work and historical geomorphic analysis, and supported by GIS and RS, this paper has researched the geomorphic dynamic characteristics and evolution rules and the artificial effects on erosion and deposition of the Laizhou shoal since 1958, when many reservoirs were built, and a great amount of sand began to be reduced. The results show that the Laizhou shoal has been moving northward while the nearby Diaolongzui spit moving northward because of the geomorphic-dynamics between them since the mid-19th century. The sand made up of the shoal has come directly from the Diaolongzui coast, and ultimately from the rivers which empties into the Bohai Sea across the NE direction stretching coast from the Diaolongzui spit to the Qimudao island. There are two main depositional dynamic mechanisms, which have been controlling the shoal erosion and deposition processes. One is that when the ebb tidal current from the south-west Laizhou bay is retarded by the shoal, it turns to flow along the west-northern striking shoal with a secondary transverse circulation made up of shoalward currents in the bottom and upwelling currents near the shoal. So, erosion took place on the SW part, and deposition on the top part of the shoal, which led to the shoal migrating toward NE as a whole. Another is that the centrifugal effect of tidal currents around the pointed end of the shoal causes a secondary circulation made up of shoalward currents in the bottom and upwelling currents in the upper. So, the suspended sand deposits on the NW part of the shoal. References | Related Articles | Metrics

Characteristics of the Subglacially-formed Debris-rich Chemical Deposits and Subglacial Processes of Qiangyong Glacier LUO Risheng, CAO Jun, LIU Gengnian, CUI Zhijiu 2003, 58 (5):  757-764.  doi: 10.11821/xb200305015 Abstract ( )   PDF (1084KB) ( )   Save Subglacially-formed debris-rich chemical deposits were found both on bedrock surface and in bedrock crevice at the edge of Qiangyong Glacier, one of the continental glaciers in Tibet. Grain size distribution, internal structures and chemical components of the chemical deposits were analyzed. It can be inferred that the temperature of some parts of the ice-bedrock interface is close to melting point and there exists pressure melting water under Qiangyong Glacier. Debris, especially those from continental aerosols, can release Ca++ in the water. At the lee-side of obstacles on glacier bed the CO2 in the melted water might escape from the water and the melted water might refreeze due to the dramatically reduced pressure, making the enrichment and precipitation of CaCO3. The existence of subglacial melting water and the process of regelation under Qiangyong Glacier indicates that sliding could contribute some proportion to the total movement of Qiangyong glacier and it belongs to multiplex cold-temperate glaciers. References | Related Articles | Metrics

Emergy Evaluation and Assessment of Sustainability on the Eco-Economic System of Xinjiang LI Haitao, LIAO Yingchun, YAN Maochao, HU Dan 2003, 58 (5):  765-772.  doi: 10.11821/xb200305016 Abstract ( )   PDF (903KB) ( )   Save In this paper, on the basis of emergy analysis, indices and ratios are calculated and analysed in the eco-economic system of Xinjiang from 1991 to 1999. The research results showed that: 1) the emergy yield ratio decreased from 23.6 in 1991 to 11.7 in 1999, however, the ratio in each year was more than 1, which indicates Xinjiang is an export-oriented eco-economic region with much more emergy exporting to the outsides; 2) the emergy-based sustainability index changed from 262 in 1991 to 64.1 in 1999, which indicates Xinjiang has made certain progress in resource utilization and economic development, but it is still a less-developed region; 3) the environmental loading ratios of Xinjiang increased from 0.09 in 1991 to 0.18 in 1999, which indicates the ratios are much less than the average level of the world, and there is still greater potential for further economic development; 4) the upper limits of population carrying capacity in Xinjiang is more than 100 million persons, which indicates it is rational to have immigrants for the development of Xinjiang in the future. References | Related Articles | Metrics

A Geographical Investigation into Knowledge Spillovers between Regions WANG Zheng, , MA Cuifang, WANG Ying, WENG Guilan 2003, 58 (5):  773-780.  doi: 10.11821/xb200305017 Abstract ( )   PDF (1095KB) ( )   Save In geography realm, regional interaction is a classic topic, regional spillover as spatial interaction is the main type of regional interaction in the new era, for it is the power force of new economy. In this paper, we investigated the actual materials of the regional diffusion about two scientific ideas with key words: sustainable development and knowledge- based economy. This demonstration analysis results show: 1. Knowledge spillovers between regions not only have relations with knowledge gaps, but also are related with regional need that the geographic characteristic decides; in areas where ecological quality is poor, sustainable development idea is more welcomed. 2. Similarly to many economic geographic phenomena, knowledge spillovers strength reduce process satisfies exponential decay law with distance; Wilson's spatial interaction model is meaningful for knowledge spillovers. 3. Knowledge spillovers are active driven by regional need but they are not ramifications of trade so far as classical idea is concerned. As a supplementary result, this paper draws the conclusion that the spreading processes of sustainable development and knowledge-based economy of China have come into steady state, the situations are shown in Figures 1 and 2. References | Related Articles | Metrics

Several Geocomputation Problems on Tourism Distribution Center Planning DENG Yue, WANG Zheng, , LIU Yang, ZHOU Wei, LI Shan 2003, 58 (5):  781-788.  doi: 10.11821/xb200305018 Abstract ( )   PDF (1117KB) ( )   Save In this paper, firstly, Dredge's structure model of tourism region was developed as a base, and a hierarchical multi-center structure was suggested; secondly, the paper applies Airport model, multi-Weber's problem model and newsboy model in operational research respectively to study the choice of tourism distribution center, the profit maximization location of Tourism Service Facility and the optimization bed number. In order to carry out computation, this paper combines GIS technique with Visual Basic6.0 (VB). All the programs, which compute the choice of tourism distribution center (hub), the profit maximization location of Tourism Service Facility and the optimization bed number, are written by using VB, and finally geographical display and analysis function are completed by using MapObject Control. The core parts of the programs have been identified in this paper, including the choice of Tourism Distribution Center, the choice of Tourism Service Facility location, and the computation of optimization bed number. An application to Shangrao, China was shown in this paper. References | Related Articles | Metrics

A Research on Distributed Time Variant Gain Modeling XIA Jun, , WANG Gangsheng, LV Aifeng, TAN Ge 2003, 58 (5):  789-796.  doi: 10.11821/xb200305019 Abstract ( )   PDF (1228KB) ( )   Save Based on requirement of distributed hydrological modelling and considering the real conditions of the arid and semi-arid regions in China, this paper develops a Distributed Time Variant Gain Model (DTVGM) by coupling the mechanism and special digit information of water cycle with hydrologic system approach. It simulates the movement of the water in the soil-vegetation-atmosphere system, describes the relation between the cellular grids in the horizontal direction, and performs mathematical calculations of the surface water and the groundwater on the watershed cellular grids divided by DEM. DTVGM includes two components: one is runoff generation process on grid elements; the other is flow routing process based on ranked grids. At present, the runoff generation process is divided into two layers in the vertical direction: the upper layer is the surface flow; the lower layer is the subsurface flow. On the other hand, the kinematic wave models are applied to simulate the flow routing process. The article also addresses a case study on Heihe mountainous basin by applying DTVGM. The basin, with an area of 9,569.25 km2, is divided into 38,277 grid elements; and the grids are partitioned into 456 ranks for flow routing. References | Related Articles | Metrics