On the basis of discussing the influencing mode of plant moisture stress on plant physiological process and the division of soil moisture availability range, the water suction values partitioning soil moisture were pu...On the basis of discussing the influencing mode of plant moisture stress on plant physiological process and the division of soil moisture availability range, the water suction values partitioning soil moisture were put forward, and then the corresponding water moistures under water stress were obtained by conversing together with characteristic curve of water moisture.展开更多
Soil water retention data are essential for irrigation scheduling and determination of irrigation frequency. However, direct measurement of this characteristic is time consuming and expensive and furthermore its spati...Soil water retention data are essential for irrigation scheduling and determination of irrigation frequency. However, direct measurement of this characteristic is time consuming and expensive and furthermore its spatial and temporal variabilities in field scales increase the number of measurements. Different pedotransfer functions, such as Saxton et al., Campbell, Vereecken et al., l^awls and Brakensiek, WSsten et al., Rajkni et al., Ghorbani Dashtaki and Homaee, Zacharias and Wessolek, and Rosetta, were evaluated to estimate soil water retention of saline and saline-alkali soils collected from south of Tehran, Iran. The saturation-extract conductivity of all the 68 samples and exchangeable sodium percentage of more than half of them were measured to be greater than 4 dS m-1 and 15%, respectively. The calculated Akaike's information criterion values showed that Saxton et al. and Campbell models were the best in estimation of soil water retention curve and total available water, respectively.展开更多
At present,thermal conductivity is usually taken as a constant value in the calculation of building energy con-sumption and load.However,in the actual use of building materials,they are exposed to the environment with...At present,thermal conductivity is usually taken as a constant value in the calculation of building energy con-sumption and load.However,in the actual use of building materials,they are exposed to the environment with continuously changing temperature and relative humidity.The thermal conductivity of materials will inevitably change with temperature and humidity,leading to deviations in the estimation of energy consumption in the building.Therefore,in this study,variations in the thermal conductivity of eight common building insulation materials(glass wool,rock wool,silica aerogel blanket,expanded polystyrene,extruded polystyrene,phenolic foam,foam ceramic and foam glass)with temperature(in the range of 20-60°C)and relative humidity(in the range of 0-100%)were studied by experimental methods.The results show that the thermal conductivity of these common building insulation materials increased approximately linearly with increasing temperature with maxi-mum growth rates from 3.9 to 22.7%in the examined temperature range.Due to the structural characteristics of materials,the increasing thermal conductivity of different materials varies depending on the relative humidity.The maximum growth rates of thermal conductivity with humidity ranged from 8.2 to 186.7%.In addition,the principles of selection of building insulation materials in different humidity regions were given.The research re-sults of this paper aim to provide basic data for the accurate value of thermal conductivity of building insulation materials and for the calculation of energy consumption.展开更多
There is an increasing trend to incorporate the basin hydrological model into the traditional land surface model (LSM) to improve the description of hydrological processes in them. For incorporating with the Noah LS...There is an increasing trend to incorporate the basin hydrological model into the traditional land surface model (LSM) to improve the description of hydrological processes in them. For incorporating with the Noah LSM, a new rainfall-runoff model named XXT (the first X stands for Xinanjiang, the second X stands for hybrid, and T stands for TOPMODEL) was developed and presented in this study, based on the soil moisture storage capacity distribution curve (SMSCC), some essential modules of the Xinanjiang model, together with the simple model framework of the TOPMODEL (a topography based hydrological model). The innovation of XXT is that the water table is incorporated into SMSCC and it connects the surface runoff production with base flow production. This improves the description of the dynamically varying saturated areas that produce runoff and also captures the physical underground water level. XXT was tested in a small-scale watershed Youshuijie (946 km2) and a large-scale watershed Yinglouxia (10009 km2) in China. The results show that XXT has better performance against the TOPMODEL and the Xinanjiang model for the two watersheds in both the calibration period and the validation period in terms of the Nash-Sutcliffe efficiency. Moreover, XXT captures the largest peak flow well for both the small: and large-scale watersheds during the validation period, while the TOPMODEL produces significant overestimates or underestimates, so does the Xinanjiang model.展开更多
Soil CO_2efflux(SCE) is an important component of ecosystem CO_2 exchange and is largely temperature and moisture dependent, providing feedback between C cycling and the climate system. We used a precipitation manip...Soil CO_2efflux(SCE) is an important component of ecosystem CO_2 exchange and is largely temperature and moisture dependent, providing feedback between C cycling and the climate system. We used a precipitation manipulation experiment to examine the effects of precipitation treatment on SCE and its dependences on soil temperature and moisture in a semiarid grassland. Precipitation manipulation included ambient precipitation, decreased precipitation(- 43%), or increased precipitation(+ 17%). The SCE was measured from July2013 to December 2014, and CO_2 emission during the experimental period was assessed.The response curves of SCE to soil temperature and moisture were analyzed to determine whether the dependence of SCE on soil temperature or moisture varied with precipitation manipulation. The SCE significantly varied seasonally but was not affected by precipitation treatments regardless of season. Increasing precipitation resulted in an upward shift of SCE–temperature response curves and rightward shift of SCE–moisture response curves,while decreasing precipitation resulted in opposite shifts of such response curves. These shifts in the SCE response curves suggested that increasing precipitation strengthened the dependence of SCE on temperature or moisture, and decreasing precipitation weakened such dependences. Such shifts affected the predictions in soil CO_2 emissions for different precipitation treatments. When considering such shifts, decreasing or increasing precipitation resulted in 43 or 75% less change, respectively, in CO_2 emission compared with changes in emissions predicted without considering such shifts. Furthermore, the effects of shifts in SCE response curves on CO_2 emission prediction were greater during the growing than the non-growing season.展开更多
文摘On the basis of discussing the influencing mode of plant moisture stress on plant physiological process and the division of soil moisture availability range, the water suction values partitioning soil moisture were put forward, and then the corresponding water moistures under water stress were obtained by conversing together with characteristic curve of water moisture.
文摘Soil water retention data are essential for irrigation scheduling and determination of irrigation frequency. However, direct measurement of this characteristic is time consuming and expensive and furthermore its spatial and temporal variabilities in field scales increase the number of measurements. Different pedotransfer functions, such as Saxton et al., Campbell, Vereecken et al., l^awls and Brakensiek, WSsten et al., Rajkni et al., Ghorbani Dashtaki and Homaee, Zacharias and Wessolek, and Rosetta, were evaluated to estimate soil water retention of saline and saline-alkali soils collected from south of Tehran, Iran. The saturation-extract conductivity of all the 68 samples and exchangeable sodium percentage of more than half of them were measured to be greater than 4 dS m-1 and 15%, respectively. The calculated Akaike's information criterion values showed that Saxton et al. and Campbell models were the best in estimation of soil water retention curve and total available water, respectively.
基金This work was supported by the National Natural Science Foundation of China(No.51878534,No.51878532 and U20A20311)State Key Laboratory of Green Building in Western China.
文摘At present,thermal conductivity is usually taken as a constant value in the calculation of building energy con-sumption and load.However,in the actual use of building materials,they are exposed to the environment with continuously changing temperature and relative humidity.The thermal conductivity of materials will inevitably change with temperature and humidity,leading to deviations in the estimation of energy consumption in the building.Therefore,in this study,variations in the thermal conductivity of eight common building insulation materials(glass wool,rock wool,silica aerogel blanket,expanded polystyrene,extruded polystyrene,phenolic foam,foam ceramic and foam glass)with temperature(in the range of 20-60°C)and relative humidity(in the range of 0-100%)were studied by experimental methods.The results show that the thermal conductivity of these common building insulation materials increased approximately linearly with increasing temperature with maxi-mum growth rates from 3.9 to 22.7%in the examined temperature range.Due to the structural characteristics of materials,the increasing thermal conductivity of different materials varies depending on the relative humidity.The maximum growth rates of thermal conductivity with humidity ranged from 8.2 to 186.7%.In addition,the principles of selection of building insulation materials in different humidity regions were given.The research re-sults of this paper aim to provide basic data for the accurate value of thermal conductivity of building insulation materials and for the calculation of energy consumption.
基金Supported by the National Basic Research and Development (973) Program of China (2010CB951404)National Nature Science Foundation of China (40971024 and 31101073)+2 种基金Natural Science Research Fund of the Education Department of Sichuan Province (09ZA075)Open Research Fund of the Meteorological Center for Huaihe Watershed (HRM200905)China Meteorological Administration Special Public Welfare Research Fund (GYHY200906007)
文摘There is an increasing trend to incorporate the basin hydrological model into the traditional land surface model (LSM) to improve the description of hydrological processes in them. For incorporating with the Noah LSM, a new rainfall-runoff model named XXT (the first X stands for Xinanjiang, the second X stands for hybrid, and T stands for TOPMODEL) was developed and presented in this study, based on the soil moisture storage capacity distribution curve (SMSCC), some essential modules of the Xinanjiang model, together with the simple model framework of the TOPMODEL (a topography based hydrological model). The innovation of XXT is that the water table is incorporated into SMSCC and it connects the surface runoff production with base flow production. This improves the description of the dynamically varying saturated areas that produce runoff and also captures the physical underground water level. XXT was tested in a small-scale watershed Youshuijie (946 km2) and a large-scale watershed Yinglouxia (10009 km2) in China. The results show that XXT has better performance against the TOPMODEL and the Xinanjiang model for the two watersheds in both the calibration period and the validation period in terms of the Nash-Sutcliffe efficiency. Moreover, XXT captures the largest peak flow well for both the small: and large-scale watersheds during the validation period, while the TOPMODEL produces significant overestimates or underestimates, so does the Xinanjiang model.
基金supported by the National Natural Science Foundation of China (Nos. 41271315, 41571130082)the Program for New Century Excellent Talents in University (No. NCET-13-0487)the Program from Chinese Academy of Sciences (No. 2014371)
文摘Soil CO_2efflux(SCE) is an important component of ecosystem CO_2 exchange and is largely temperature and moisture dependent, providing feedback between C cycling and the climate system. We used a precipitation manipulation experiment to examine the effects of precipitation treatment on SCE and its dependences on soil temperature and moisture in a semiarid grassland. Precipitation manipulation included ambient precipitation, decreased precipitation(- 43%), or increased precipitation(+ 17%). The SCE was measured from July2013 to December 2014, and CO_2 emission during the experimental period was assessed.The response curves of SCE to soil temperature and moisture were analyzed to determine whether the dependence of SCE on soil temperature or moisture varied with precipitation manipulation. The SCE significantly varied seasonally but was not affected by precipitation treatments regardless of season. Increasing precipitation resulted in an upward shift of SCE–temperature response curves and rightward shift of SCE–moisture response curves,while decreasing precipitation resulted in opposite shifts of such response curves. These shifts in the SCE response curves suggested that increasing precipitation strengthened the dependence of SCE on temperature or moisture, and decreasing precipitation weakened such dependences. Such shifts affected the predictions in soil CO_2 emissions for different precipitation treatments. When considering such shifts, decreasing or increasing precipitation resulted in 43 or 75% less change, respectively, in CO_2 emission compared with changes in emissions predicted without considering such shifts. Furthermore, the effects of shifts in SCE response curves on CO_2 emission prediction were greater during the growing than the non-growing season.