The grain size composition, distribution characteristics and spatial variation of eolian sand soil on distinct positions across two longitudinal dunes and interdune areas were studied by means of conventional grain si...The grain size composition, distribution characteristics and spatial variation of eolian sand soil on distinct positions across two longitudinal dunes and interdune areas were studied by means of conventional grain size analysis and geostatistical methods. In the study, 184 samples of eolian sand soil from the 0-30cm layer were systemically collected and measured from two longitudinal dunes and interdunes in the southern Gurbantunggut Desert. The results show that the dominant grain sizes are fine and very fine sands, and the differences of grain size compositions between the distinct geomorphologic positions are significant. The contents of clay and silt are highest on the interdune areas and lowest on the crests, and higher on the leeward slopes than on the windward slopes. The contents of very fine and fine sands are highest on the windward slopes and lowest on the crests. The contents of medium, coarse and very coarse sands are lowest on the interdune lands, and highest on the crests, and are identical on the two slopes. The coarser sizes (phi(1)) and mean sizes (Mz) for eolian sand soil all have a varying tendency from fine to coarse sizes with interdune area -> leeward slope -> windward slope -> crest, and the sorting (sigma) are poorly to well sorted. The results of geostatistical analysis reveal that phi(1), Mz and a values are moderately to strongly spatially autocorrelated. The values of the spatially correlated ranges are phi(1) < sigma < Mz. The spatial variation for these grain size parameters is significant across the longitudinal dune landscape. From the crests towards the bottom of the slope, there is a varying gradient of zonal distribution, and the gradient values on the leeward slopes are larger than sites on the windward slopes.展开更多
Improving crop water productivity is necessary for ensuring food security. To quantify the water utilization in grain production from multiple perspectives, gross inflow water productivity(WPg), generalized agricultur...Improving crop water productivity is necessary for ensuring food security. To quantify the water utilization in grain production from multiple perspectives, gross inflow water productivity(WPg), generalized agricultural water productivity(WPa), evapotranspiration water productivity(WPET) and irrigation water productivity(WPI) were examined in this study. This paper calculated and analyzed the temporal and spatial variation in these water productivity(WP) indices in the irrigated land of Heilongjiang Province. The results showed that almost all of the municipal WP indices increased from 2007 to 2015. The four indices showed large differences in scientific connotation and numerical performance, and their degrees of spatial variation were ranked as WPI>WPa>WPg>WPET. The spatial patterns of WP indices in different years were similar; the central and southern regions on the Songnen Plain and the eastern region had high WP values, while those of the northern region were low. Each WP index was used to evaluate the relationship between the input of water resources and the output of grain between different regions. Most cities had the potential to improve WP by reducing the input of irrigation water. Furthermore, the results provided recommendations to decision makers to plan for efficient use of water resources in different cities.展开更多
基金supported by the National Basic Research Program of China (2009CB825105)
文摘The grain size composition, distribution characteristics and spatial variation of eolian sand soil on distinct positions across two longitudinal dunes and interdune areas were studied by means of conventional grain size analysis and geostatistical methods. In the study, 184 samples of eolian sand soil from the 0-30cm layer were systemically collected and measured from two longitudinal dunes and interdunes in the southern Gurbantunggut Desert. The results show that the dominant grain sizes are fine and very fine sands, and the differences of grain size compositions between the distinct geomorphologic positions are significant. The contents of clay and silt are highest on the interdune areas and lowest on the crests, and higher on the leeward slopes than on the windward slopes. The contents of very fine and fine sands are highest on the windward slopes and lowest on the crests. The contents of medium, coarse and very coarse sands are lowest on the interdune lands, and highest on the crests, and are identical on the two slopes. The coarser sizes (phi(1)) and mean sizes (Mz) for eolian sand soil all have a varying tendency from fine to coarse sizes with interdune area -> leeward slope -> windward slope -> crest, and the sorting (sigma) are poorly to well sorted. The results of geostatistical analysis reveal that phi(1), Mz and a values are moderately to strongly spatially autocorrelated. The values of the spatially correlated ranges are phi(1) < sigma < Mz. The spatial variation for these grain size parameters is significant across the longitudinal dune landscape. From the crests towards the bottom of the slope, there is a varying gradient of zonal distribution, and the gradient values on the leeward slopes are larger than sites on the windward slopes.
基金Supported by National Natural Science Foundation of China(51479032)National Key R&D Plan(2017YFC0406002)
文摘Improving crop water productivity is necessary for ensuring food security. To quantify the water utilization in grain production from multiple perspectives, gross inflow water productivity(WPg), generalized agricultural water productivity(WPa), evapotranspiration water productivity(WPET) and irrigation water productivity(WPI) were examined in this study. This paper calculated and analyzed the temporal and spatial variation in these water productivity(WP) indices in the irrigated land of Heilongjiang Province. The results showed that almost all of the municipal WP indices increased from 2007 to 2015. The four indices showed large differences in scientific connotation and numerical performance, and their degrees of spatial variation were ranked as WPI>WPa>WPg>WPET. The spatial patterns of WP indices in different years were similar; the central and southern regions on the Songnen Plain and the eastern region had high WP values, while those of the northern region were low. Each WP index was used to evaluate the relationship between the input of water resources and the output of grain between different regions. Most cities had the potential to improve WP by reducing the input of irrigation water. Furthermore, the results provided recommendations to decision makers to plan for efficient use of water resources in different cities.
