Variation in vegetation cover in Inner Mongolia has been previously studied by the remote sensing data spanning only one decade. However, spatial and temporal variations in vegetation cover based on the newly released...Variation in vegetation cover in Inner Mongolia has been previously studied by the remote sensing data spanning only one decade. However, spatial and temporal variations in vegetation cover based on the newly released GIMMS NDVI3g data spanning nearly thirty years have yet to be analyzed. In this study, we applied the methods of the maximum value composite （MVC） and Pearson＇s correlation coefficient to analyze the variations of vegetation cover in Inner Mongolia based on GIMMS NDVI3g data spanning from 1982 to 2013. Our results indicate that the normalized difference vegetation index （NDVI） increased at a rate of 0.0003/a during the growing seasons despite of the drier and hotter climate in Inner Mongolia during the past three decades. We also found that vegetation cover in the southern agro-pastoral zone significantly increased, while it significantly decreased in the central Alxa. The variations in vegetation cover were not significant in the eastern and central regions. NDVI is positively correlated with precipitation （r=0.617, P=0.000） and also with air temperature （r=0.425, P=0.015）, but the precipitation had a greater effect than the air temperature on the vegetation variations in Inner Mongolia.展开更多
Drought is one of the severe meteorological disasters and causes of serious losses for agricultural productions, and early assessment of drought hazard degree is critical in management of maize farming. This study pro...Drought is one of the severe meteorological disasters and causes of serious losses for agricultural productions, and early assessment of drought hazard degree is critical in management of maize farming. This study proposes a novel method for assessment of maize drought hazard in different growth stages. First, the study divided the maize growth period into four critical growth stages, including seeding, elongation, tasseling, and filling. Second, maize drought causal factors were selected and the fuzzy membership function was established. Finally, the study built a fuzzy gamma model to assess maize drought hazards, and the gamma 0.93 was finally established using Monte Carlo Analysis. Performing fuzzy gamma operation with 0.93 for gamma and classifying the area yielded a map of maize drought hazards with four zones of light, moderate, severe, and extreme droughts. Using actual field collected data, seven selected samples for drought hazard degree were examined, the model output proved to be a valid tool in the assessment maize drought hazard. This model will be very useful in analyzing the spatial change of maize drought hazard and influence on yield, which is significant for drought management in major agricultural areas.展开更多
Early in the 1930 s,two relatively large earthquakes(Kosout,magnitude 6.8,and Talarrud,magnitude 5.8)shook the eastern Mazandaran,northern Iran.Despite the historical and instrumental seismic activity of the eastern r...Early in the 1930 s,two relatively large earthquakes(Kosout,magnitude 6.8,and Talarrud,magnitude 5.8)shook the eastern Mazandaran,northern Iran.Despite the historical and instrumental seismic activity of the eastern region of Mazandaran,little is known about the status of seismotectonics and consequences of these earthquakes.This paper presents a compilation of available data from early reports of these earthquakes with new structural,geomorphic and local data on the effects of this earthquake,especially co-seismic landslides and liquefaction,to assess the seismotectonics and probable causative faults of the earthquakes.It is proposed that the close times of occurrence of two earthquakes might be due to local loading or triggering effect of the first earthquake on the second one.Like many other instrumental earthquakes in the Central Alborz,it is difficult to find the exact causative faults of important earthquakes,however the Qadikola,Chachkam or North Alborz Fault have the potential of producing Kosout earthquake and the Lalehband fault is more promising for Talarrud earthquake.Additionally,the structural complexity of the area is also discussed in the form of a hybrid tectonic model.In this model,the boundary zone of thick-skinned and active thin-skinned domains has more structural complexity than outer portions.Konim-Badeleh Shahvar pop-up structure is bounded by major faults with thick-skinned deformation style.The role of older inherited fault structures and their interaction with low-slope Neogene thrusts driven from north to south by crustal tectonics and deformation is discussed.Co-seismic landslides and rock falls have great potential to be investigated in the Alborz Range for identification of prehistoric earthquakes.展开更多
基金supported by the National Key Technology R&D Program of China(2013BAK05B01,2013BAK05B02)
文摘Variation in vegetation cover in Inner Mongolia has been previously studied by the remote sensing data spanning only one decade. However, spatial and temporal variations in vegetation cover based on the newly released GIMMS NDVI3g data spanning nearly thirty years have yet to be analyzed. In this study, we applied the methods of the maximum value composite （MVC） and Pearson＇s correlation coefficient to analyze the variations of vegetation cover in Inner Mongolia based on GIMMS NDVI3g data spanning from 1982 to 2013. Our results indicate that the normalized difference vegetation index （NDVI） increased at a rate of 0.0003/a during the growing seasons despite of the drier and hotter climate in Inner Mongolia during the past three decades. We also found that vegetation cover in the southern agro-pastoral zone significantly increased, while it significantly decreased in the central Alxa. The variations in vegetation cover were not significant in the eastern and central regions. NDVI is positively correlated with precipitation （r=0.617, P=0.000） and also with air temperature （r=0.425, P=0.015）, but the precipitation had a greater effect than the air temperature on the vegetation variations in Inner Mongolia.
基金supported by the National High-Tech R&D Program of China (2011BAD32B00-04)the National Basic Research Program of China (2010CB951102)+1 种基金the National Natural Science Foundation of China (41071326)the National Scientific Research Special Project of Public Sectors (Agriculture) of China (200903041)
文摘Drought is one of the severe meteorological disasters and causes of serious losses for agricultural productions, and early assessment of drought hazard degree is critical in management of maize farming. This study proposes a novel method for assessment of maize drought hazard in different growth stages. First, the study divided the maize growth period into four critical growth stages, including seeding, elongation, tasseling, and filling. Second, maize drought causal factors were selected and the fuzzy membership function was established. Finally, the study built a fuzzy gamma model to assess maize drought hazards, and the gamma 0.93 was finally established using Monte Carlo Analysis. Performing fuzzy gamma operation with 0.93 for gamma and classifying the area yielded a map of maize drought hazards with four zones of light, moderate, severe, and extreme droughts. Using actual field collected data, seven selected samples for drought hazard degree were examined, the model output proved to be a valid tool in the assessment maize drought hazard. This model will be very useful in analyzing the spatial change of maize drought hazard and influence on yield, which is significant for drought management in major agricultural areas.
基金funded by the first author’s grant at Shahid Beheshti University。
文摘Early in the 1930 s,two relatively large earthquakes(Kosout,magnitude 6.8,and Talarrud,magnitude 5.8)shook the eastern Mazandaran,northern Iran.Despite the historical and instrumental seismic activity of the eastern region of Mazandaran,little is known about the status of seismotectonics and consequences of these earthquakes.This paper presents a compilation of available data from early reports of these earthquakes with new structural,geomorphic and local data on the effects of this earthquake,especially co-seismic landslides and liquefaction,to assess the seismotectonics and probable causative faults of the earthquakes.It is proposed that the close times of occurrence of two earthquakes might be due to local loading or triggering effect of the first earthquake on the second one.Like many other instrumental earthquakes in the Central Alborz,it is difficult to find the exact causative faults of important earthquakes,however the Qadikola,Chachkam or North Alborz Fault have the potential of producing Kosout earthquake and the Lalehband fault is more promising for Talarrud earthquake.Additionally,the structural complexity of the area is also discussed in the form of a hybrid tectonic model.In this model,the boundary zone of thick-skinned and active thin-skinned domains has more structural complexity than outer portions.Konim-Badeleh Shahvar pop-up structure is bounded by major faults with thick-skinned deformation style.The role of older inherited fault structures and their interaction with low-slope Neogene thrusts driven from north to south by crustal tectonics and deformation is discussed.Co-seismic landslides and rock falls have great potential to be investigated in the Alborz Range for identification of prehistoric earthquakes.
