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    20 July 2010, Volume 65 Issue 7 Previous Issue    Next Issue
    Drought Monitoring and Its Impacts Assessment in Southwest China Using Remote Sensing in the Spring of 2010
    LI Qiangzi, YAN Nana, ZHANG Feifei, CHANG Sheng, WU Bingfang
    2010, 65 (7):  771-780.  doi: 10.11821/xb201007001
    Abstract ( )   PDF (26335KB) ( )   Save

    The authors carried out drought monitoring and its impacts assessment in Southwest China using CCD and IRS data obtained from China-made satellite HJ-1 in the spring of 2010. The following techniques were proposed: 1) Drought monitoring using LST and NDVI derived from HJ-1 CCD and IRS; 2) Water resource assessment by comparison of water area sampled within the severe drought regions; 3) Effects of the drought on crops. Crop growing curves from time series MODIS NDVI were compared to assess the effects of drought on crop conditions, arable land area, crop planting proportion. Crop planting structure and area fraction of different drought grades were used to introduce crop area under the drought condition. A crop yield loss look-up table was also built-up based on field-experiment results digested from articles. The results showed that: i) the drought occurred mainly in Guangxi, Yunnan, Guizhou, Sichuan and Chongqing, especially in the northwest of Guangxi, central and northeast of Yunnan and the southwest of Guizhou. ii) the severe drought resulted in the withdrawal of surface water bodies, and more than 2/3 of water bodies disappeared. iii) Since last October, crop growing curves have presented obvious restrain due to the drought, Among the crops, winter wheat, seedrape and sugarcane has been greatly affected. There were about 9.13×105 hm2 of winter wheat, 5.43×105 hm2 of seedrape and 9.00×105 hm2 of sugarcane suffering the drought, respectively. For winter wheat, there would be a damage of 8.3×105 t, and 13.7% of the total production of Chongqing, Sichuan, Guizhou and Yunnan, accounting for only 0.8% of the country. The damage would not do harm to the country's food security but will exert influence on regional grain supply-demand balance. The drought has also affected the nursery of autumn crops and transplant of rice.

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    The Effect of Mountain Base Elevation on the Altitude of Timberline in the Southeastern Eurasia: A Study on the Quantification of Mass Elevation Effect
    HAN Fang, ZHANG Baiping, TAN Jing, ZHU Yunhai, YAO Yonghui
    2010, 65 (7):  781-788.  doi: 10.11821/xb201007002
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    This paper focuses on the method of quantifying the phenomenon of mass elevation effect (massenerhebungs effect). Geographers have taken notice of mass elevation effect and its influence on mountain altitudinal belts for more than 100 years. But so far, our knowledge on mass elevation effect has been very limited, let alone its quantitative effect on mountain altitudinal belts. Geographers and botanists have established many unitary or dibasic fitting models between mountain altitudinal belts' distribution and longitude or latitude, or both. But most of these models involve small scales and could not be expanded to other regions; while others are established for the northern hemisphere or the whole globe with very low precision. The reason is that these models neglect one of the most important factors controlling the distribution of altitudinal belts—mass elevation effect. It is well known that the higher the mountain range, the greater the mass elevation effect is. So, mountain's base altitude could be a represent of mass elevation effect. We collect 173 samples of forest line distribution, and use latitude, longitude and mountain base elevation (MBE) as independent variables to build a multiple linear regression equation for timberline altitude in the southeastern Eurasian continent. The result turned out that the contribution of latitude, longitude and mountain base elevation to timber line distribution reaches 30.60%, 26.53%, and 42.87%, respectively. North of northern latitude 32°, the contribution for each of the three factors amounts to 53.08%, 21.25%, and 25.67%, respectively; to the south, the contribution is 14.94%, 48.98%, and 36.08%, respectively. The results indicate that MBE, serving as a proxy indicator of mass elevation effect, is a significant factor determining the elevation of altitudinal belts. Compared with other factors, it is more stable and independent in affecting forest line elevation. Of course, mass elevation effect is also determined by other factors, including mountain's volume, the distance to the edge of a land mass, the structures of the mountains nearby, etc. They need to be included in the study of mass elevation effect in the future.

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    The Influence of Land Use Change on Soil Development and over the Loess Tablelands in the Northern Weihe River Basin, China
    PANG Jiangli, ZHANG Weiqing, HUANG Chunchang, ZHA Xiaochun, ZHANG Caiyun, CHANG Meirong, ZHU Meiling, DING Min
    2010, 65 (7):  789-800.  doi: 10.11821/xb201007003
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    Investigations of land use change and its impact on soil development were carried out over the loess tablelands in the northern Weihe River basin. Typical soil profiles, including 6 cultivated soil and 8 apple orchard soil were surveyed in detail, and then sampled systematically. Pedological characteristics and the structure of soil profiles were observed in the field. Particle-size distribution, magnetic susceptibility, contents of organic matter, CaCO3, trace elements, pH value and micromorphology was analyzed in laboratory. An integration of the results shows that: (1) When cultivated land was converted to apple orchard, the structure of the soil profile changed from Ap-Bc-A-Ck-C to AB-(Bc)-A-Ck-C gradually. (2) Element change occurred in the topsoil between 0 and 35 cm in depth. Magnetic susceptibility, contents of organic matter, major elements (Si, Al, Fe, K, Mg, Ca, Na) and trace elements (Cu, Co, Ni, Zn, Vi, Cr, Pb, Cs) tend to increase, and CaCO3 content and pH value tend to decrease. (3) Between 35 and 90 cm in depth, magnetic susceptibility, contents of organic matter, major and trace elements tend to decrease, and CaCO3 content tends to increase. (4) Soil properties remain unchanged below 90 cm in depth. (5) Soil porosity change is obvious. The number of the soil pores is reduced, and the average area of pores is increased. The total content of clay mineral is increased, the ratio of the residual clay to alluvial clay is reduced. The illuviation depth of secondary calcite in the cultivated soil profile occurred between 0 and 35 cm in depth. However, in apple orchard soil profile, carbonate illuviation extended to the depth of 90 cm in general. All of these evidences show that human land use change has affected soil properties and soil development in a relatively short period of time. After cultivated land was changed into apple orchard, soil properties changed mainly between 0 and 35 cm in depth, and the deeper part between 35 and 90 cm was also affected.

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    The Changing Trends of the First and Last Frost Dates over Shanxi Province for the Past 40 Years
    QIAN Jinxia, ZHANG Xia, ZHANG Jianxin, FAN Liaosheng, WU Jie
    2010, 65 (7):  801-808.  doi: 10.11821/xb201007004
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    Based on the frost date data of 52 meteorological stations over Shanxi Province from 1970 to 2009, the basic characteristics of the first and last frost dates and their changing trends were analyzed in this paper using linear trend estimation method, cumulative filter method and non-parametric statistical test method respectively, and the abrupt changing feature of the frost dates was also analyzed with Mann-Kendall method. The results show that the frost dates and frost-free period have obvious spatial and temporal changing features. Along with the latitude moving northward and the altitude rising high, the first frost appears earlier, the last frost occurs later, and the frost-free period becomes shorter. With the time changing over the past 40 years, the first frost event occurs later and the frost-free period becomes longer, while the last frost date fluctuates from year to year. For the abrupt changing feature, they all have one obvious abrupt change over the past 40 years. The abrupt change of the first frost date appears in 2000, while the abrupt changes of the last frost date and the frost-free period are detected in 1997. For the spatial distribution of their changing trend, the area in which the first frost date is postponed significantly includes the east of Jinzhong city, the north of Lüliang city, the west of Xinzhou city, the south of Yuncheng city, the northwest of Linfen city and the southern part of Datong city; the area in which the last frost date appears obviously earlier includes the east mountainous region of Jinzhong city, the eastern part of Lüliang Mountains and the western part of Xinzhou city; the area in which the frost-free period extends obviously includes the region near the Yellow River, the central-eastern part of the province and the south of Yuncheng city.

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    Water Supply Pattern Evolution of Tianjin in the Process of Urban Development
    FENG Yue, LU Chunxia, TANG Xiaofei, XIE Gaodi
    2010, 65 (7):  809-818.  doi: 10.11821/xb201007005
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    From the perspective of geography, this paper studies the evolution of Tianjin water supply pattern by taking advantage of GIS technology. The results showed that because of high salinity of groundwater, surface water from the Haihe River basin was utilized as the main water source of Tianjin in ancient and modern times. The region for water security in these two periods was the upper Haihe River close to the city. Since 1949, water conservancy facilities and water source development have been constructed step by step, and the water supply system in correspondence with the city layout has been established. Water supply structure of Tianjin was characterized by higher proportion of surface water, utilization of new types of water in small quantity and high dependence on external water. The evolution of water source and region for water security has experienced 3 stages in the last 60 years. The first stage is basically the self-supporting period from the 1950s to mid-1960s. The region for water security was confined in administrative area. The second stage lasted from the mid-1960s to early 1980s. It was an unstable period when the upper Haihe River was taken as the main region for water security and water from the Yellow River basin for emergence use. From the early 1980s to the present, the Luanhe River basin was taken as the main region for water security and water from the Yellow River basin was taken as water source for emergency, and the supply water pattern was stable by and large. In the future, utilization of external water would be larger and the proportion of surface water would be higher. Utilization amount of ground water would decrease continuously. The region for surface water security would extend to the Yangtze River Basin on the basis of the current pattern. Region for ground water security would experience further reduction.

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    Study on Cooperative Constraint Regionalization of Water Environment and the Guidance for Industrial Distribution:A Case Study of Jiangsu Province
    SUN Wei, CHEN Wen, CHEN Cheng
    2010, 65 (7):  819-827.  doi: 10.11821/xb201007006
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    Along with the rapid economic and social development in the developed areas in China, the water environment has been continuously deteriorated by the increasing amount of water pollutant discharge. Thus, water environment has already become a constraint factor to regional development. In order to coordinate the relationship between economic development and water environment, many countries have attempted water environmental function zoning so as to provide a scientific basis for the basin management. However, those researches have ignored the spatial relation between water and land area, or how the bearing capacity of water environment constrains industrial distribution. Therefore, the applied index systems concern environmental factors without considering the constraints brought by human activity to the water environment. This paper discusses the methods of cooperative constraint regionalization of water environment which is related to both the sensitivity and the pressure of water environment, including how to divide the assessed units, and how to choose and manage the assessed elements etc. Then, as a case study, Jiangsu Province is divided into four types by the method of two-dimensional quadrant analysis, namely, high-pressure and high-sensitivity area, high-pressure and low-sensitivity area, low-pressure and high-sensitivity area, and low-pressure and low-sensitivity area. Finally, this paper presents the scheme of industrial distribution adjustment, which provides a scientific basis for making different industrial policies as well as harmonizing the industrial development and the bearing capacity of water environment.

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    Spatio-temporal Patterns of Sediment and Runoff Changes in the Poyang Lake Basin and Underlying Causes
    SUN Peng, ZHANG Qiang, CHEN Xiaohong, CHEN Yongqin David
    2010, 65 (7):  828-840.  doi: 10.11821/xb201007007
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    Annual runoff and annual suspended sediment loads at five hydrological gauging stations (Waizhou, Meigang, Lijiadu, Hushan and Datong) in the five tributaries of the Poyang Lake Basin (Ganjiang River, Fuhe River, Xinjiang River, Raohe River and Xiushui River) were analyzed using Mann-Kendall trend test and linear regression method. The results indicate that (1) the changing patterns of runoff and sediment loads are different over the Poyang Lake Basin. No significant trend is found for annual runoff at all the stations at >95% confidence level. However, the changes of sediment loads demonstrate different pictures in the Poyang Lake Basin. The sediment loads show a decreasing trend at Waizhou, Meigang and Hushan stations (the increasing trend of Waizhou station is significant at > 95% confidence level after around the year 1998), but an increasing trend at Ljiadu and Xiushui stations; (2) the forest coverage changes have greater impacts on sediment load than on the runoff; extensive deforestation contributed less to the increase of sediment loads in 1958. Large-scale deforestation caused significant increase of sediment loads during 1971-1985; (3) Hydraulic facilities, especially water reservoirs, exerted more influences on sediment load changes than on runoff, being the major cause next to the decreasing trend of sediment loads. The results of this study are of great practical significance to a better understanding of the hydrological responses to climate changes and human activities across the Poyang Lake Basin, as a freshwater wetland in China.

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    Mapping Runoff Based on Water Balance:A Case Study of the Huaihe River Basin above Bengbu
    YAN Ziqi, XIA Jun, Lars GOTTSCHALK
    2010, 65 (7):  841-852.  doi: 10.11821/xb201007008
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    This presentation describes a hydro-stochastic approach method for producing choropleth maps of average runoff and computing mean discharge along the main river network. The approach applied to mean annual runoff is based on geostatistical interpolation procedures coupled with water balance and data uncertainty analyses. It is proved by an application in the Huaihe River Basin above Bengbu, a typical basin in China. By disaggregating the mean annual streamflow measured at the outlet of a basin to estimate water depths on elements of an exact partition of this basin, it works out gridded runoff yield maps with a resolution of 10 km × 10 km and the discharge map along the river with a 1 km basic unit in length. These results are consistent with water balance.

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    The Computation and Characteristics Analysis of Water Vapor Contents in the Tarim Basin, China
    YANG Qing, LIU Xiaoyang, CUI Caixia, LI Jun, LIU Rui
    2010, 65 (7):  853-862.  doi: 10.11821/xb201007009
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    Monthly mean water vapor contents were computed using meteorological data from 5 radiosonde stations including Hotan, Kuqa, Ruoqiang, Kashi and Minfeng around the Tarim Basin China during 1976-2006, and a formula was established involving monthly mean water vapor content and surface vapor pressure. By this formula, we obtained water vapor contents of all the 28 weather stations around the Tarim Basin and also performed EOF of water vapor contents to study its spatial pattern. Changes of vapor pressure with the height were also analysed. The water vapor contents obtained by GPS in the center and surroundings of the Tarim Basin were compared with radiosonde reports. Results show that: there are two higher water vapor areas in the Tarim Basin, one is on the west edge and the other is on the north edge, and the contents are both between 13-14 mm. These two higher centers are both in the oases near the Tarim River, Yarkant River and Aksu River. The center of the Tarim River has the lower water vapor, with the content being only between 7-8 mm, and the lowest spot is in Tazhong station. The water vapor content presents an increasing trend from the basin center to the edges, then presents a decreasing trend due to higher altitudes outside the Basin. There is good linear relationship between water vapor contents obtained from GPS and radiosonde.

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    Changes in Pan Evaporation and Its Cause over Guangdong
    FAN Lingli, GUO Pinwen, GUAN Yong, LIANG Minyan
    2010, 65 (7):  863-872.  doi: 10.11821/xb201007010
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    The observation data of 20 cm caliber evaporation pan and related meteorological elements were collected from 86 weather stations of Guangdong for 1961-2008. Statistical analysis shows that the pan evaporation in Guangdong as a whole has continuously decreased at a rate of 54.67 mm per decade, although the annual mean temperature has increased at a rate of 0.21 oC per decade. The regions with a significant drop in pan evaporation are the Pearl River Delta, as well as southwestern and eastern coastal regions of Guangdong. Only a small part of regions with a rise in pan evaporation is located in the central region of Guangdong. Through analysis of variations of the dynamic term and energy term in Penman equation, separately, it is found that the drop of pan evaporation is mainly attributed to decreases in the energy term, and that the dynamic term in the southwestern and eastern coastal regions of Guangdong is mainly attributed to decreases in the energy term in the Pearl River delta. The rise of pan evaporation is mainly due to the fact that the increase in the dynamic term is greater than the decrease in the energy term. Further investigation into tendencies of meteorological impacting factors and the correlation analysis between pan evaporation and the influencing factors show that the sunshine duration and wind peed are remarkable.

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