The characteristics of soil holding capacity for different shrub-grass patterns are important to research the mechanisms regulating vegetation on slopes.The objective of this study was to describe the characteristics ...The characteristics of soil holding capacity for different shrub-grass patterns are important to research the mechanisms regulating vegetation on slopes.The objective of this study was to describe the characteristics and mecha-nisms of soil erosion and hydraulic parameters under differ-ent vegetation patterns in the Pisha sandstone area of Inner Mongolia on lands of 8°slope gradient.We carried out field scouring experiments on five different shrub-grass patterns as treatments,viz no shrubs(GL),shrubs on the upper part of the slope(SU),middle part of the slope(SM)and lower part of the slope(SL).We designated bare slope(BL)as the control.We employed three different water flow rates(15,20,30 L·min^(−1)).Our results showed that the contribution of plant root systems to slope sediment reduction ranged from 64 to 84%.The root systems proved to be the main contributing factor to reduction of erosion by vegetation.The relationship between soil detachment rate,stream flow power,and flow unit stream power under different scouring discharge rates showed that soil detachment declined in rank order as:BL>GL>SU>SM>SL.The SL pat-tern had the lowest soil detachment rate(0.098 g·m^(−2)·s^(−1)),flow stream power(2.371 W·m^(−2)),flow unit stream power(0.165 m·s^(−1))and flow shear stress(16.986 Pa),and proved to be the best erosion combating pattern.The results of decision coefficient and path analysis showed that stream power was the most important hydraulic parameter for describing soil detachment rate.The combination of stream power and shear stress,namely Dr=0.1ω−0.03τ−0.56(R^(2)=0.924),most accurately simulated the soil detachment characteristics on slopes.Our study suggests that the risk of soil ero-sion can be reduced by planting shrub-grass mixes on these slopes.Under the conditions of limited water resources and economy,the benefit of sediment reduction can be maxi-mized by planting shrubbery on the lower parts of slopes.展开更多
Biological soil crusts are widely distributed in arid and semi-arid regions, whose formation and development have an important impact on the restoration process of the desert ecosystem. In order to explore the relatio...Biological soil crusts are widely distributed in arid and semi-arid regions, whose formation and development have an important impact on the restoration process of the desert ecosystem. In order to explore the relationship between surface airflow and development characteristics of biological soil crusts, we studied surface airflow pattern and development characteristics of biological soil crusts on the fixed dune profile through field observation. Results indicate that the speed of near-surface airflow is the lowest at the foot of windward slope and the highest at the crest, showing an increasing trend from the foot to the crest. At the leeward side, although near-surface airflow increases slightly at the lower part of the slope after an initial sudden decrease at upper part of the slope, its overall trend decreases from the crest. Wind velocity variation coefficient varied at different heights over each observation site. The thickness, shear strength of biological soil crusts and percentage of fine particles at crusts layer decreased from the slope foot to the upper part, showing that biological soil crusts are less developed in high wind speed areas and well developed in low wind speed areas. It can be seen that there is a close relationship between the distribution of biological soil crusts in different parts of the dunes and changes in airflow due to geomorphologic variation.展开更多
This paper gives a brief introduction to the emergency handling of Tangjiashan barrier lake.Some technologies for the application of geological and topographical data are summarized and the mechanism of formation of a...This paper gives a brief introduction to the emergency handling of Tangjiashan barrier lake.Some technologies for the application of geological and topographical data are summarized and the mechanism of formation of a barrier lake is analyzed.Based on the safety status evaluation,the dam breach flood point is calculated.The paper concludes with discussion of the practical effects of emergency handling scenarios and different drainage channel designs.展开更多
<div style="text-align:justify;"> Water is the key factor to ensure plant survival in the process of ecological restoration in the coal base of China northwest deserts. On the premise of meeting the mi...<div style="text-align:justify;"> Water is the key factor to ensure plant survival in the process of ecological restoration in the coal base of China northwest deserts. On the premise of meeting the mine production and living water demands, we should take measures such as dirt wastewater treatment and water-saving irrigation to increase income and reduce expenditure and allocate limited water re-sources rationally, to provide mining area ecological restoration maximum usable water resources. The mining dump has large slope and thin soil layer and it is easy to produce surface runoff. So it is particularly important to study the irrigation technology needed to satisfy vegetation restoration, on the premise of guaranteeing not to produce surface runoff and the slope stability. In this paper, through field plot test, the suitable irrigation method for mine slope, slope surface soil moisture migration characteristics and slope stability analysis were studied. Results show that three slope ir-rigation technologies have their own advantages and disadvantages. On the whole, the effect of drip irrigation is the best, micro spray irrigation is the second, infiltrating irrigation is not ideal. The permeability of mine soil slope is very strong, the infiltration rate of the slope direction is the high-est, inverse slope infiltration rate is lowest. In the process of irrigation, with the increase of soil moisture content, slope safety factor is the decreased obviously, the whole slope surface soil moisture content is 14% for the slope stability safety threshold. </div>展开更多
Exploring the impact of climate factors on vegetation phenology is crucial to understanding climate–vegetation interactions as well as carbon and water cycles in ecosystems in the context of climate change.In this ar...Exploring the impact of climate factors on vegetation phenology is crucial to understanding climate–vegetation interactions as well as carbon and water cycles in ecosystems in the context of climate change.In this article,we extracted the vegetation phenology data from 2002 to 2021 based on the dynamic threshold method in the source region of the Yangtze and Yellow Rivers.Trend and correlation analyses were used to investigate the relationship between vegetation phenology and temperature,precipitation and their spatial evolution characteristics.The results showed that:(i)From 2002 to 2021,the multi-year average start of growing season(SOS),end of growing season(EOS)and length of growing season(LOS)for plants were concentrated in May,October and 4–6 months,with a trend of 4.9 days(earlier),1.5 days(later),6.3 days/10 a(longer),respectively.(ii)For every 100 m increase in elevation,SOS,EOS and LOS were correspondingly delayed by 1.8 days,advanced by 0.8 days and shortened by 2.6 days,respectively.(iii)The impacts of temperature and precipitation on vegetation phenology varied at different stages of vegetation growth.Influencing factors of spring phenology experienced a shift from temperature to precipitation,while autumn phenology experienced precipitation followed by temperature.(iv)The climate factors in the previous period significantly affected the vegetation phenology in the study area and the spatial variability was obvious.Specifically,the temperature in April significantly affected the spring phenology and precipitation in August widely affected the autumn phenology.展开更多
Forest ecosystems play a significant role in maintaining climate stability at the regional and global scales as an important carbon sink.Regional forest carbon storage and its dynamic changes in the Pearl River Delta ...Forest ecosystems play a significant role in maintaining climate stability at the regional and global scales as an important carbon sink.Regional forest carbon storage and its dynamic changes in the Pearl River Delta have been estimated using the continuous biomass expansion factor(BEF)method based on field measurements of forests plots in different age classes and forest inventory data of three periods(1989–1993,1994–1998,1999–2003).The results show that regional carbon storage increased by 16.76%,from 48....展开更多
The regional objective ET(evapotranspiration) is defined as the quantity of water that could be con-sumed in a particular region.It varies with the water conditions and economic development stages in the region.It is ...The regional objective ET(evapotranspiration) is defined as the quantity of water that could be con-sumed in a particular region.It varies with the water conditions and economic development stages in the region.It is also constrained by the requirement of benign environment cycle.At the same time,it must meet the demands of sustainable economic growth and the construction of harmony society.Objective ET based water resources distribution will replace the conventional method,which empha-sizes the balance between the water demand and the water supply.It puts focus on the reasonable water consumption instead of the forecasted water demand,which is usually greater than the actual one.In this paper,we calculated the objective ET of 2010 year level in Tianjin by an analysis-integra-tion-assessment method.Objective ET can be classified into two parts:controllable ET and uncontrol-lable ET.Controllable ET includes the ET from irrigation land and the ET from resident land,among which the former can be calculated with soil moisture model and evapotranspiration model,while the latter can be calculated by water use ration and water consumption rate.The uncontrollable ET can be calculated with the distributed hydrological model and the remote sensing monitoring model.The two models can be mutually calibrated.In this paper,eight schemes are put forward based on different portfolios of water resources.The objective ET of each scheme was calculated and the results were assessed and analyzed.Finally,an optimal scheme was recommended.展开更多
基金supported financially by the National Natural Science Foundation of China (41701327,31870708,51879155,515 79157 and 5177915 6)the National Key Research and Development Program of China(2016YFC0500504)the Inner Mongolia Natural Science Foundation (2017BS0405)
文摘The characteristics of soil holding capacity for different shrub-grass patterns are important to research the mechanisms regulating vegetation on slopes.The objective of this study was to describe the characteristics and mecha-nisms of soil erosion and hydraulic parameters under differ-ent vegetation patterns in the Pisha sandstone area of Inner Mongolia on lands of 8°slope gradient.We carried out field scouring experiments on five different shrub-grass patterns as treatments,viz no shrubs(GL),shrubs on the upper part of the slope(SU),middle part of the slope(SM)and lower part of the slope(SL).We designated bare slope(BL)as the control.We employed three different water flow rates(15,20,30 L·min^(−1)).Our results showed that the contribution of plant root systems to slope sediment reduction ranged from 64 to 84%.The root systems proved to be the main contributing factor to reduction of erosion by vegetation.The relationship between soil detachment rate,stream flow power,and flow unit stream power under different scouring discharge rates showed that soil detachment declined in rank order as:BL>GL>SU>SM>SL.The SL pat-tern had the lowest soil detachment rate(0.098 g·m^(−2)·s^(−1)),flow stream power(2.371 W·m^(−2)),flow unit stream power(0.165 m·s^(−1))and flow shear stress(16.986 Pa),and proved to be the best erosion combating pattern.The results of decision coefficient and path analysis showed that stream power was the most important hydraulic parameter for describing soil detachment rate.The combination of stream power and shear stress,namely Dr=0.1ω−0.03τ−0.56(R^(2)=0.924),most accurately simulated the soil detachment characteristics on slopes.Our study suggests that the risk of soil ero-sion can be reduced by planting shrub-grass mixes on these slopes.Under the conditions of limited water resources and economy,the benefit of sediment reduction can be maxi-mized by planting shrubbery on the lower parts of slopes.
基金supported by National Natural Science Foundation of China(Grant No.41201050)Scientific Re-search Funds of Institute of Water Resources and Hydro-power Research of China and National"Twelfth Five-Year"Plan for Science&Technology(2012BAD16B0202)
文摘Biological soil crusts are widely distributed in arid and semi-arid regions, whose formation and development have an important impact on the restoration process of the desert ecosystem. In order to explore the relationship between surface airflow and development characteristics of biological soil crusts, we studied surface airflow pattern and development characteristics of biological soil crusts on the fixed dune profile through field observation. Results indicate that the speed of near-surface airflow is the lowest at the foot of windward slope and the highest at the crest, showing an increasing trend from the foot to the crest. At the leeward side, although near-surface airflow increases slightly at the lower part of the slope after an initial sudden decrease at upper part of the slope, its overall trend decreases from the crest. Wind velocity variation coefficient varied at different heights over each observation site. The thickness, shear strength of biological soil crusts and percentage of fine particles at crusts layer decreased from the slope foot to the upper part, showing that biological soil crusts are less developed in high wind speed areas and well developed in low wind speed areas. It can be seen that there is a close relationship between the distribution of biological soil crusts in different parts of the dunes and changes in airflow due to geomorphologic variation.
文摘This paper gives a brief introduction to the emergency handling of Tangjiashan barrier lake.Some technologies for the application of geological and topographical data are summarized and the mechanism of formation of a barrier lake is analyzed.Based on the safety status evaluation,the dam breach flood point is calculated.The paper concludes with discussion of the practical effects of emergency handling scenarios and different drainage channel designs.
文摘<div style="text-align:justify;"> Water is the key factor to ensure plant survival in the process of ecological restoration in the coal base of China northwest deserts. On the premise of meeting the mine production and living water demands, we should take measures such as dirt wastewater treatment and water-saving irrigation to increase income and reduce expenditure and allocate limited water re-sources rationally, to provide mining area ecological restoration maximum usable water resources. The mining dump has large slope and thin soil layer and it is easy to produce surface runoff. So it is particularly important to study the irrigation technology needed to satisfy vegetation restoration, on the premise of guaranteeing not to produce surface runoff and the slope stability. In this paper, through field plot test, the suitable irrigation method for mine slope, slope surface soil moisture migration characteristics and slope stability analysis were studied. Results show that three slope ir-rigation technologies have their own advantages and disadvantages. On the whole, the effect of drip irrigation is the best, micro spray irrigation is the second, infiltrating irrigation is not ideal. The permeability of mine soil slope is very strong, the infiltration rate of the slope direction is the high-est, inverse slope infiltration rate is lowest. In the process of irrigation, with the increase of soil moisture content, slope safety factor is the decreased obviously, the whole slope surface soil moisture content is 14% for the slope stability safety threshold. </div>
基金supported by the National Key Research and Development Project(2022YFC3201704)the National Natural Science Foundation of China(52079008,52009006,52109038)+2 种基金the Research Fund of Key Laboratory of Water Management and Water Security for Yellow River Basin,Ministry of Water Resources(2023-SYSJJ-10)the Natural Science Foundation of Hubei Province(2022CFB554,2022CFD037)National Public Research Institutes for Basic R&D Operating Expenses Special Project(CKSF2023311/SZ).
文摘Exploring the impact of climate factors on vegetation phenology is crucial to understanding climate–vegetation interactions as well as carbon and water cycles in ecosystems in the context of climate change.In this article,we extracted the vegetation phenology data from 2002 to 2021 based on the dynamic threshold method in the source region of the Yangtze and Yellow Rivers.Trend and correlation analyses were used to investigate the relationship between vegetation phenology and temperature,precipitation and their spatial evolution characteristics.The results showed that:(i)From 2002 to 2021,the multi-year average start of growing season(SOS),end of growing season(EOS)and length of growing season(LOS)for plants were concentrated in May,October and 4–6 months,with a trend of 4.9 days(earlier),1.5 days(later),6.3 days/10 a(longer),respectively.(ii)For every 100 m increase in elevation,SOS,EOS and LOS were correspondingly delayed by 1.8 days,advanced by 0.8 days and shortened by 2.6 days,respectively.(iii)The impacts of temperature and precipitation on vegetation phenology varied at different stages of vegetation growth.Influencing factors of spring phenology experienced a shift from temperature to precipitation,while autumn phenology experienced precipitation followed by temperature.(iv)The climate factors in the previous period significantly affected the vegetation phenology in the study area and the spatial variability was obvious.Specifically,the temperature in April significantly affected the spring phenology and precipitation in August widely affected the autumn phenology.
基金supported by the National Natural Sci-ence Foundation of China(No.49571064)"985 Project"of Environment and Pollution Control from the Ministry of Education of Chinathe Natural Science Foundationof Guangdong Province(No.021740)
文摘Forest ecosystems play a significant role in maintaining climate stability at the regional and global scales as an important carbon sink.Regional forest carbon storage and its dynamic changes in the Pearl River Delta have been estimated using the continuous biomass expansion factor(BEF)method based on field measurements of forests plots in different age classes and forest inventory data of three periods(1989–1993,1994–1998,1999–2003).The results show that regional carbon storage increased by 16.76%,from 48....
基金Supported by the National Basic Research Program of China (973 Project) (Grant No. 2006CB403401) the National Natural Science Fundation of China (Grant No. 50721006)
文摘The regional objective ET(evapotranspiration) is defined as the quantity of water that could be con-sumed in a particular region.It varies with the water conditions and economic development stages in the region.It is also constrained by the requirement of benign environment cycle.At the same time,it must meet the demands of sustainable economic growth and the construction of harmony society.Objective ET based water resources distribution will replace the conventional method,which empha-sizes the balance between the water demand and the water supply.It puts focus on the reasonable water consumption instead of the forecasted water demand,which is usually greater than the actual one.In this paper,we calculated the objective ET of 2010 year level in Tianjin by an analysis-integra-tion-assessment method.Objective ET can be classified into two parts:controllable ET and uncontrol-lable ET.Controllable ET includes the ET from irrigation land and the ET from resident land,among which the former can be calculated with soil moisture model and evapotranspiration model,while the latter can be calculated by water use ration and water consumption rate.The uncontrollable ET can be calculated with the distributed hydrological model and the remote sensing monitoring model.The two models can be mutually calibrated.In this paper,eight schemes are put forward based on different portfolios of water resources.The objective ET of each scheme was calculated and the results were assessed and analyzed.Finally,an optimal scheme was recommended.
