A variety of landscape properties have been modeled successfully using topographic indices such as topographic wetness index (TWI), defined as ln(a/tanβ), where a is the specific upslope area and β is the surface sl...A variety of landscape properties have been modeled successfully using topographic indices such as topographic wetness index (TWI), defined as ln(a/tanβ), where a is the specific upslope area and β is the surface slope. In this study, 25 m spatial resolution from digital elevation models (DEM) data were used to investigate the scale-dependency of TWI values when converting DEMs to 50 and 100 m. To investigate the impact of different spatial resolution, the two lower resolution DEMs were interpolated to the original 25 m grid size. In addition, to compare different flow-direction algorithms, a second objective was to evaluate differences in spatial patterns. Thus the values of TWI were compared in two different ways: 1) distribution functions and their statistics;and 2) cell by cell comparison of DEMs with the same spatial resolution but different flow- directions. As in previous TWI studies, the computed specific upstream is smaller, on average, at higher resolution. TWI variation decreased with increasing grid size. A cell by cell comparison of the TWI values of the 50 and 100 m DEMs showed a low correlation with the TWI based on the 25 m DEM. The results showed significant differences between different flow-diretction algorithms computed for DEMs with 25, 50 and 100 m spatial resolution.展开更多
[Objective] The research aimed to analyze the evolution situation of dry and wet degree in Benxi area in recent 57 years.[Method] By using the annual,quarterly and monthly temperature and precipitation data in Benxi a...[Objective] The research aimed to analyze the evolution situation of dry and wet degree in Benxi area in recent 57 years.[Method] By using the annual,quarterly and monthly temperature and precipitation data in Benxi area during 1953-2009,the interdecadal variations of temperature,precipitation,dry and wet index were analyzed.[Result] The annual average temperature in Benxi area displayed the obvious increase trend,and the linear trend rate was 0.29 ℃/10 a.But the precipitation showed the obvious decrease trend,and the linear trend rate was-29.01 mm/10 a.The dry and wet index showed the decrease trend,and the linear trend rate was-33.61 mm/10 a,which closely related to the rise of temperature and the decrease of precipitation after the 1980s.[Conclusion] It showed the warming-drying development trend in Benxi area.展开更多
Wettability of acid volcanic reservoir rock from the Hailar Oilfield, China, was studied with crude oils of different acid numbers generated from an original crude oil with an acid number of 3.05 mg KOH/g. The modifed...Wettability of acid volcanic reservoir rock from the Hailar Oilfield, China, was studied with crude oils of different acid numbers generated from an original crude oil with an acid number of 3.05 mg KOH/g. The modifed oils and their resultant acid numbers were： A （2.09 mg KOH/g）, B （0.75 mg KOH/g）, C （0.47 mg KOH/g）, D （0.30 mg KOH/g）, and E （0.18 mg KOH/g）. Contact angles and improved Amott water indexes were measured to study the effects of temperature and acid number on the wettability of the acid volcanic reservoir rock. Experimental results indicated that the wettability was not sensitive to variation in temperature when using the same oil, but the acid number of the crude oil was a key factor in changing the wettability of the rock. The Amott water index, Iw was an exponential function of the acid number, and the Amott water index increased as the acid number decreased （i.e. Amott water index exponentially decreased with the acid number increase）. The Iw value of the core saturated with oil A, with an acid number of 2.09 mg KOH/g, ranged from 0.06 to 0.11, which indicated low water wetness. If the acid number of the oil decreased to 0.18 mg KOH/g, the Iw value increased to 0.95, which indicated strong water wetness. The contact angle decreased from 80~ to 35~ when the aid number decreased from 0.75 to 0.18 mg KOH/g, indicating a change towards more water wet conditions. The oil recovery by spontaneous imbibition of water also increased as the acid number of the oil decreased. As an example, at 80 ~C, the recovery of Oil A with an acid number of 2.09 mg KOH/g was only 7.6%, while Oil E with an acid number of 0.18 mg KOH/g produced 56.4%, i.e. an increase of 48.8%.展开更多
Based on the mean yearly precipitation and the total yearly evaporation data of 295 meteorological stations in China in 1951-1999, the aridity index is calculated in this paper. According to the aridity index, the cli...Based on the mean yearly precipitation and the total yearly evaporation data of 295 meteorological stations in China in 1951-1999, the aridity index is calculated in this paper. According to the aridity index, the climatic regions in China are classified into three types, namely, arid region, semi-arid region and humid region. Dry and wet climate boundaries in China fluctuate markedly and differentiate greatly in each region in the past 50 years. The fluctuation amplitudes are 20-400 km in Northeast China, 40-400 km in North China, 30-350 km in the eastern part of Northwest China and 40-370 km in Southwest China. Before the 1980s (including 1980), the climate tended to be dry in Northeast China and North China, to be wet in the eastern part of Northwest China and very wet in Southwest China. Since the 1990s there have been dry signs in Southwest China, the eastern part of Northwest China and North China. The climate becomes wetter in Northeast China. Semi-arid region is the transitional zone between humid and arid regions, the monsoon edge belt in China, and the susceptible region of environmental evolution. At the end of the 1960s dry and wet climate in China witnessed abrupt changes, changing wetness into dryness. Dry and wet climate boundaries show the fluctuation characteristics of the whole shifts and the opposite fluctuations of eastward, westward, southward and northward directions. The fluctuations of climatic boundaries and the dry and wet variations of climate have distinctive interdecadal features.展开更多
文摘A variety of landscape properties have been modeled successfully using topographic indices such as topographic wetness index (TWI), defined as ln(a/tanβ), where a is the specific upslope area and β is the surface slope. In this study, 25 m spatial resolution from digital elevation models (DEM) data were used to investigate the scale-dependency of TWI values when converting DEMs to 50 and 100 m. To investigate the impact of different spatial resolution, the two lower resolution DEMs were interpolated to the original 25 m grid size. In addition, to compare different flow-direction algorithms, a second objective was to evaluate differences in spatial patterns. Thus the values of TWI were compared in two different ways: 1) distribution functions and their statistics;and 2) cell by cell comparison of DEMs with the same spatial resolution but different flow- directions. As in previous TWI studies, the computed specific upstream is smaller, on average, at higher resolution. TWI variation decreased with increasing grid size. A cell by cell comparison of the TWI values of the 50 and 100 m DEMs showed a low correlation with the TWI based on the 25 m DEM. The results showed significant differences between different flow-diretction algorithms computed for DEMs with 25, 50 and 100 m spatial resolution.
文摘[Objective] The research aimed to analyze the evolution situation of dry and wet degree in Benxi area in recent 57 years.[Method] By using the annual,quarterly and monthly temperature and precipitation data in Benxi area during 1953-2009,the interdecadal variations of temperature,precipitation,dry and wet index were analyzed.[Result] The annual average temperature in Benxi area displayed the obvious increase trend,and the linear trend rate was 0.29 ℃/10 a.But the precipitation showed the obvious decrease trend,and the linear trend rate was-29.01 mm/10 a.The dry and wet index showed the decrease trend,and the linear trend rate was-33.61 mm/10 a,which closely related to the rise of temperature and the decrease of precipitation after the 1980s.[Conclusion] It showed the warming-drying development trend in Benxi area.
文摘Wettability of acid volcanic reservoir rock from the Hailar Oilfield, China, was studied with crude oils of different acid numbers generated from an original crude oil with an acid number of 3.05 mg KOH/g. The modifed oils and their resultant acid numbers were： A （2.09 mg KOH/g）, B （0.75 mg KOH/g）, C （0.47 mg KOH/g）, D （0.30 mg KOH/g）, and E （0.18 mg KOH/g）. Contact angles and improved Amott water indexes were measured to study the effects of temperature and acid number on the wettability of the acid volcanic reservoir rock. Experimental results indicated that the wettability was not sensitive to variation in temperature when using the same oil, but the acid number of the crude oil was a key factor in changing the wettability of the rock. The Amott water index, Iw was an exponential function of the acid number, and the Amott water index increased as the acid number decreased （i.e. Amott water index exponentially decreased with the acid number increase）. The Iw value of the core saturated with oil A, with an acid number of 2.09 mg KOH/g, ranged from 0.06 to 0.11, which indicated low water wetness. If the acid number of the oil decreased to 0.18 mg KOH/g, the Iw value increased to 0.95, which indicated strong water wetness. The contact angle decreased from 80~ to 35~ when the aid number decreased from 0.75 to 0.18 mg KOH/g, indicating a change towards more water wet conditions. The oil recovery by spontaneous imbibition of water also increased as the acid number of the oil decreased. As an example, at 80 ~C, the recovery of Oil A with an acid number of 2.09 mg KOH/g was only 7.6%, while Oil E with an acid number of 0.18 mg KOH/g produced 56.4%, i.e. an increase of 48.8%.
基金The Knowledge Innovation Project of CAS NO. KZCX1-10-06
文摘Based on the mean yearly precipitation and the total yearly evaporation data of 295 meteorological stations in China in 1951-1999, the aridity index is calculated in this paper. According to the aridity index, the climatic regions in China are classified into three types, namely, arid region, semi-arid region and humid region. Dry and wet climate boundaries in China fluctuate markedly and differentiate greatly in each region in the past 50 years. The fluctuation amplitudes are 20-400 km in Northeast China, 40-400 km in North China, 30-350 km in the eastern part of Northwest China and 40-370 km in Southwest China. Before the 1980s (including 1980), the climate tended to be dry in Northeast China and North China, to be wet in the eastern part of Northwest China and very wet in Southwest China. Since the 1990s there have been dry signs in Southwest China, the eastern part of Northwest China and North China. The climate becomes wetter in Northeast China. Semi-arid region is the transitional zone between humid and arid regions, the monsoon edge belt in China, and the susceptible region of environmental evolution. At the end of the 1960s dry and wet climate in China witnessed abrupt changes, changing wetness into dryness. Dry and wet climate boundaries show the fluctuation characteristics of the whole shifts and the opposite fluctuations of eastward, westward, southward and northward directions. The fluctuations of climatic boundaries and the dry and wet variations of climate have distinctive interdecadal features.
