Due to the influence of human activities such as cultivation and urban construction,the ecosystem of the Yellow River Basin(YRB)is subjected to increased vulnerability and even potential risk of destruction.Ecological...Due to the influence of human activities such as cultivation and urban construction,the ecosystem of the Yellow River Basin(YRB)is subjected to increased vulnerability and even potential risk of destruction.Ecological restoration has led to an increase in vegetation,but excessive afforestation conversely results in low survival rate of trees,water shortages,and biodiversity loss.It is of great significance for achieving sustainable development of forests to reasonable revegetation in the region.At present,the potential distribution pattern of dominant species and their mixed forms in the basin has not been effectively studied.This study simulated the potential distribution of dominant vegetation in the YRB based on Maximum Entropy(Max Ent)and Genetic Algorithm for Rule-Set Prediction(GARP)and explored the impact of human interference on it by employing land use as the environmental filter to distinguish the regions of human activities.We further predicted the potential distribution of typically mixed forests and discussed their human interference.The main results are as follows:(1)Except for Caragana korshinskii,all models had good above performance(0.7<the mean AUC<1).Except for Caragana korshinskii,the area under the curve(AUC)for 90%of the models indicated that Max Ent performed better than GARP,and Max Ent easily lead to over-fitting while GARP predicted a wider range.(2)Except for Nitraria tangutorum,the dominant types of vegetation such as Pinus tabulaeformis,Platycladus orientalis,and Hippophae rhamnoides mainly distributed in southern Gansu,Shaanxi,and south-central Shanxi.Among them,the largest suitable area of Artemisia gmelinii and Stipa bungeana(High suitable area)were approximately 56.7×104 km2(38.8%)and 54.7×104 km2(28.5%)with the area occupied by large-scale cultivation being 17.5×104 km2(39.4%)and 18.9×104 km2(48%),respectively,which indicated human activities caused great damage to the core growth regions of these vegetation.(3)Mean temperature of coldest quarter or month mainly constrained the growth of most vegetation in the YRB in terms of temperature,while precipitation of wettest/driest month is one of the dominant factors.However,some vegetation responded differently to other meteorological factors due to niche differences.(4)Most of the mixed forests were distributed in southern Gansu,Shaanxi,and Shanxi provinces;its middle and high suitable areas were mainly concentrated in Shaanxi and southern and central Shanxi,where the cultivated land had occupied most of them.Therefore,the results showed that the restoration of herbaceous vegetation such as Artemisia gmelinii and Stipa bungeana has a high potential and it is appropriate that the measures for afforestation should be concentrated in the areas like the lower reaches of the Weihe,Jinghe,and Beiluo rivers and Luliang Mountain,where the cultivated land overlaps with the high suitable areas of the corresponding vegetation and the mixed forests with less water consumption and wide distribution,such as Caragana korshinskii-Hippophae rhamnoides,Pinus tabulaeformis-Quercus liaotungensis,and Ostryopsis davidiana-Stipa bungeana-Hippophae rhamnoides.The results of this study can provide effective guidance for mixed forest plantations and vegetation conservation in the YRB.展开更多
The sediment distributed and insolated under lake was collected for experiments. The nutrient layer distribution conditions of sampled sediment and its physical and chemical characteristics were analyzed to simulate a...The sediment distributed and insolated under lake was collected for experiments. The nutrient layer distribution conditions of sampled sediment and its physical and chemical characteristics were analyzed to simulate and assess the influence degree to lake water quality. Based on the dynamic water exchanging experiments the nutrient release process in sediment and influence mechanism to substance exchanging on water-sediment interface was studied, and the correlation between the changing content of total phosphors and total nitrogen in sediment and covered water were analyzed for setting up a simulation model. At the same time the influence degree is explained in detail. The experimental results indicated that even if clean water without nutrient contents was used for water exchangement so as to decrease pollution or prevent eutrophication, however owing to the vertical nutrient distribution in lake sediment, it will lead to the increasing release amount greatly especially when the organic nutrient contained in sediment turns into inorganic status because of isolation. Besides the release process of total phosphate (TP) and total nitrogen (TN) were modeled and each nutrient's exchanging equation at interface caused by covered water nutrient concentration changing was set up. According to the simulating prediction, TP and TN content of cover water will also sustain a steady higher level in a long period. The nutrient release amount of sediment is not only affected by the covered water concentration but also connects with accumulative time. The experiments provide the fundamental theoretical and practical basis for taking ecological restoration project. And research is helpful to prevent or restore lake eutrophication.展开更多
Analyzed in this paper are the influencing factors, characteristics, and mechanism of land-sea interaction for the Taihu Lake Basin. The course of mass movement and energy transformation between land and sea in the Ta...Analyzed in this paper are the influencing factors, characteristics, and mechanism of land-sea interaction for the Taihu Lake Basin. The course of mass movement and energy transformation between land and sea in the Taihu Lake Basin has experienced three different stages, namely, ocean predominance, balance between land and sea, and land predominance. In the paper the process of the formation and the evolution of the Taihu Lake is studied considering the land-sea interaction.展开更多
With the development of protected cultivation of vegetables in China, it is necessary to study the water requirements of crops in greenhouses. Lysimeter experiments were carried out to investigate tomato (2001) and ...With the development of protected cultivation of vegetables in China, it is necessary to study the water requirements of crops in greenhouses. Lysimeter experiments were carried out to investigate tomato (2001) and cowpea (2004) crop evapotranspiration (ETc) in an unheated greenhouse in Eastern China. Results showed remarkably reduced crop evapotranspiration inside the greenhouse as compared with that outside. ETc increased with the growth of the crops, and varied in accordance with the temperature inside the greenhouse and 20-cm pan evaporation outside, reaching its maximum value at the stage when plants’ growth was most active. Differences between the variation of crop evapotranspiration and pan evaporation inside the greenhouse were caused by shading of the pan in the later period when the crops were taller than the location where the pan was installed, 70 cm above ground. The ratio of crop evapotranspiration to pan evaporation was not constant as reported in previous studies, and the variation of the inside ratio αin lagged behind that of the outside ratio αout. Simulation of crop evapotranspiration based on 20-cm pan evaporation inside the greenhouse is more reasonable than that based on 20-cm pan evaporation outside, although pan evaporation outside is more consistent with ETc than that inside. The value of αin, calculated based on air temperature, relative humidity, and ground temperature inside, plays a dominant role in the calculation of ETc. As the crop height increases, altering the location of the inside pan and placing it above the canopy, out of the shade, would help to achieve more reasonable values of crop evapotranspiration.展开更多
Climate change scenarios, predicted using the regional climate modeling system of PRECIS (providing regional cli-mates for impacts studies), were used to derive three-layer variable infiltration capacity (VIC-3L) land...Climate change scenarios, predicted using the regional climate modeling system of PRECIS (providing regional cli-mates for impacts studies), were used to derive three-layer variable infiltration capacity (VIC-3L) land surface model forthe simulation of hydrologic processes at a spatial resolution of 0.25° × 0.25° in the Haihe River Basin. Three climatescenarios were considered in this study: recent climate (1961-1990), future climate A2 (1991-2100) and future climateB2 (1991-2100) with A2 and B2 being two storylines of future emissions developed with the Intergovernmental Panel onClimate Change (IPCC) special report on emissions scenarios. Overall, under future climate scenarios A2 and B2, theHaihe River Basin would experience warmer climate with increased precipitation, evaporation and runoff production ascompared with recent climate, but would be still likely prone to water shortages in the period of 2031-2070. In addition,under future climate A2 and B2, an increase in runoff during the wet season was noticed, indicating a future rise in theflood occurrence possibility in the Haihe River Basin.展开更多
The study area was designed and constructed, based on the simplification of aconceptual model, to develop a three-dimensional groundwater flow model for simulation oftwo-layers system. Finite difference groundwater fl...The study area was designed and constructed, based on the simplification of aconceptual model, to develop a three-dimensional groundwater flow model for simulation oftwo-layers system. Finite difference groundwater flow model was constructed for the CentralSonghuajiang River alluvial plain in Northeast China, with the coverage of 786. 6km^2. The gridnetworks with a spacing of 474. 4m by 509. 5m were used to cover the model area. The trial-and-errortechnique was used to calibrate the model. The sensitivity of the simulations to the modelparameters was studied -and the most sensitive parameters that controlling the residual headsdistribution in the Songhuajiang River valley were defined.展开更多
Precise comprehensive evaluation of flood disaster loss is significant for the prevention and mitigation of flood disasters. Here, one of the difficulties involved is how to establish a model capable of describing the...Precise comprehensive evaluation of flood disaster loss is significant for the prevention and mitigation of flood disasters. Here, one of the difficulties involved is how to establish a model capable of describing the complex relation between the input and output data of the system of flood disaster loss. Genetic programming (GP) solves problems by using ideas from genetic algorithm and generates computer programs automatically. In this study a new method named the evaluation of the grade of flood disaster loss (EGFD) on the basis of improved genetic programming (IGP) is presented (IGP-EGFD). The flood disaster area and the direct economic loss are taken as the evaluation indexes of flood disaster loss. Obviously that the larger the evaluation index value, the larger the corresponding value of the grade of flood disaster loss is. Consequently the IGP code is designed to make the value of the grade of flood disaster be an increasing function of the index value. The result of the application of the IGP-EGFD model to Henan Province shows that a good function expression can be obtained within a bigger searched function space; and the model is of high precision and considerable practical significance. Thus, IGP-EGFD can be widely used in automatic modeling and other evaluation systems.展开更多
It is important and necessary to get a much longer precipitation series in order to research features of drought/flood and climate change. Based on dryness and wetness grades series of 18 stations in Northern China of...It is important and necessary to get a much longer precipitation series in order to research features of drought/flood and climate change. Based on dryness and wetness grades series of 18 stations in Northern China of 533 years from 1470 to 2002, the Moving Cumulative Frequency Method (MCFM) was developed, moving average precipitation series from 1499 to 2002 were reconstructed by testing three kinds of average precipitation, and the features of ell mate change and dry and wet periods were researched by using reconstructed precipitation series in the present paper. The results showed that there were good relationship between the reconstructed precipitation series and the observation precipiration series sincc 1954 and their relative root mean-square error were below 1.89%, that the relation between reconstructed series and the dryness and wetness grades series were nonlinear and this nonlinear relation implied that reconstructed series were reliable and could became foundation data for researching evolution of the drought and flood. Analysis of climate change upon reconstructed precipitation series revealed that although drought intensity of recent dry period from mid- dle 1970s of 20th century until early 21st century was not the strongest in historical climate of Northern China, intensity and duration of wet period was a great deal decreasing and shortening respectively, climate evolve to aridification situa- tion in Northern China.展开更多
Evaporation plays an important role in water balance on the land surface. In Northern China, the evaporation series of the recent 115 years was reconstructed on the basis of Yhornthwaite evaporation formula. The chara...Evaporation plays an important role in water balance on the land surface. In Northern China, the evaporation series of the recent 115 years was reconstructed on the basis of Yhornthwaite evaporation formula. The characteristics of the reconstructed series were analyzed using 10-year running mean filter, power spectrum method, and running t-text of abrupt changes on the paper. The results showed that there were remarkable interannual fluctuations with timescales of about quasi-8-year, 3-4-year, and quasi-2-year, and interdecadal oscillations with timescales of 57.5-year, quasi-23-year, and l l.5-year. Meanwhile, the abrupt changes of the evaporation series were also of interdecadal timescale. Either interannual fluctuations or interdecadal oscillations of evaporation were closely related to variations in air temperatures and precipitation.展开更多
To improve the Xinanjiang model, the runoff generating from infiltration excess is added to the model. The another 6 parameters are added to Xinanjiang model. In prin ciple, the improved Xinanjiang model can be used t...To improve the Xinanjiang model, the runoff generating from infiltration excess is added to the model. The another 6 parameters are added to Xinanjiang model. In prin ciple, the improved Xinanjiang model can be used to simulate runoff in the humid, semi-humid and also semi-arid regions. The application in Yi River shows the improved Xinanjiang model could forecast discharge with higher acetrracy and can satisfy the practical requirements,It also shows thai the improved model is reasonable.展开更多
基金performed in the framework of the National Science Fund for Distinguished Young Scholars(31700370)。
文摘Due to the influence of human activities such as cultivation and urban construction,the ecosystem of the Yellow River Basin(YRB)is subjected to increased vulnerability and even potential risk of destruction.Ecological restoration has led to an increase in vegetation,but excessive afforestation conversely results in low survival rate of trees,water shortages,and biodiversity loss.It is of great significance for achieving sustainable development of forests to reasonable revegetation in the region.At present,the potential distribution pattern of dominant species and their mixed forms in the basin has not been effectively studied.This study simulated the potential distribution of dominant vegetation in the YRB based on Maximum Entropy(Max Ent)and Genetic Algorithm for Rule-Set Prediction(GARP)and explored the impact of human interference on it by employing land use as the environmental filter to distinguish the regions of human activities.We further predicted the potential distribution of typically mixed forests and discussed their human interference.The main results are as follows:(1)Except for Caragana korshinskii,all models had good above performance(0.7<the mean AUC<1).Except for Caragana korshinskii,the area under the curve(AUC)for 90%of the models indicated that Max Ent performed better than GARP,and Max Ent easily lead to over-fitting while GARP predicted a wider range.(2)Except for Nitraria tangutorum,the dominant types of vegetation such as Pinus tabulaeformis,Platycladus orientalis,and Hippophae rhamnoides mainly distributed in southern Gansu,Shaanxi,and south-central Shanxi.Among them,the largest suitable area of Artemisia gmelinii and Stipa bungeana(High suitable area)were approximately 56.7×104 km2(38.8%)and 54.7×104 km2(28.5%)with the area occupied by large-scale cultivation being 17.5×104 km2(39.4%)and 18.9×104 km2(48%),respectively,which indicated human activities caused great damage to the core growth regions of these vegetation.(3)Mean temperature of coldest quarter or month mainly constrained the growth of most vegetation in the YRB in terms of temperature,while precipitation of wettest/driest month is one of the dominant factors.However,some vegetation responded differently to other meteorological factors due to niche differences.(4)Most of the mixed forests were distributed in southern Gansu,Shaanxi,and Shanxi provinces;its middle and high suitable areas were mainly concentrated in Shaanxi and southern and central Shanxi,where the cultivated land had occupied most of them.Therefore,the results showed that the restoration of herbaceous vegetation such as Artemisia gmelinii and Stipa bungeana has a high potential and it is appropriate that the measures for afforestation should be concentrated in the areas like the lower reaches of the Weihe,Jinghe,and Beiluo rivers and Luliang Mountain,where the cultivated land overlaps with the high suitable areas of the corresponding vegetation and the mixed forests with less water consumption and wide distribution,such as Caragana korshinskii-Hippophae rhamnoides,Pinus tabulaeformis-Quercus liaotungensis,and Ostryopsis davidiana-Stipa bungeana-Hippophae rhamnoides.The results of this study can provide effective guidance for mixed forest plantations and vegetation conservation in the YRB.
基金The National Natural Science Foundation of China (No. 50239030) and the State Key Laboratory of Hydrology-Water Resources andHydraulic Engineering of Hohai University (No. 2003400519)
文摘The sediment distributed and insolated under lake was collected for experiments. The nutrient layer distribution conditions of sampled sediment and its physical and chemical characteristics were analyzed to simulate and assess the influence degree to lake water quality. Based on the dynamic water exchanging experiments the nutrient release process in sediment and influence mechanism to substance exchanging on water-sediment interface was studied, and the correlation between the changing content of total phosphors and total nitrogen in sediment and covered water were analyzed for setting up a simulation model. At the same time the influence degree is explained in detail. The experimental results indicated that even if clean water without nutrient contents was used for water exchangement so as to decrease pollution or prevent eutrophication, however owing to the vertical nutrient distribution in lake sediment, it will lead to the increasing release amount greatly especially when the organic nutrient contained in sediment turns into inorganic status because of isolation. Besides the release process of total phosphate (TP) and total nitrogen (TN) were modeled and each nutrient's exchanging equation at interface caused by covered water nutrient concentration changing was set up. According to the simulating prediction, TP and TN content of cover water will also sustain a steady higher level in a long period. The nutrient release amount of sediment is not only affected by the covered water concentration but also connects with accumulative time. The experiments provide the fundamental theoretical and practical basis for taking ecological restoration project. And research is helpful to prevent or restore lake eutrophication.
基金This work was financially supported by Science and Technology Innovation Fund of Ministry of Water Resources ofChina (Grant No.SCX2004-03)
文摘Analyzed in this paper are the influencing factors, characteristics, and mechanism of land-sea interaction for the Taihu Lake Basin. The course of mass movement and energy transformation between land and sea in the Taihu Lake Basin has experienced three different stages, namely, ocean predominance, balance between land and sea, and land predominance. In the paper the process of the formation and the evolution of the Taihu Lake is studied considering the land-sea interaction.
基金supported by the National High Technology Research and Development Program of China (Grant No 2006AA100202)the Foundation of Excellent Doctoral Dissertations of China (Grant No 200546)
文摘With the development of protected cultivation of vegetables in China, it is necessary to study the water requirements of crops in greenhouses. Lysimeter experiments were carried out to investigate tomato (2001) and cowpea (2004) crop evapotranspiration (ETc) in an unheated greenhouse in Eastern China. Results showed remarkably reduced crop evapotranspiration inside the greenhouse as compared with that outside. ETc increased with the growth of the crops, and varied in accordance with the temperature inside the greenhouse and 20-cm pan evaporation outside, reaching its maximum value at the stage when plants’ growth was most active. Differences between the variation of crop evapotranspiration and pan evaporation inside the greenhouse were caused by shading of the pan in the later period when the crops were taller than the location where the pan was installed, 70 cm above ground. The ratio of crop evapotranspiration to pan evaporation was not constant as reported in previous studies, and the variation of the inside ratio αin lagged behind that of the outside ratio αout. Simulation of crop evapotranspiration based on 20-cm pan evaporation inside the greenhouse is more reasonable than that based on 20-cm pan evaporation outside, although pan evaporation outside is more consistent with ETc than that inside. The value of αin, calculated based on air temperature, relative humidity, and ground temperature inside, plays a dominant role in the calculation of ETc. As the crop height increases, altering the location of the inside pan and placing it above the canopy, out of the shade, would help to achieve more reasonable values of crop evapotranspiration.
基金the Knowledge Innovation Key Project of Chinese Academy of Sciences (No. KZCX2-SW-317),the National Natural Science Foundation of China (Nos. 90411007 and 40275023), and the Hundred Talents Program ofChinese Academy of Sciences.
文摘Climate change scenarios, predicted using the regional climate modeling system of PRECIS (providing regional cli-mates for impacts studies), were used to derive three-layer variable infiltration capacity (VIC-3L) land surface model forthe simulation of hydrologic processes at a spatial resolution of 0.25° × 0.25° in the Haihe River Basin. Three climatescenarios were considered in this study: recent climate (1961-1990), future climate A2 (1991-2100) and future climateB2 (1991-2100) with A2 and B2 being two storylines of future emissions developed with the Intergovernmental Panel onClimate Change (IPCC) special report on emissions scenarios. Overall, under future climate scenarios A2 and B2, theHaihe River Basin would experience warmer climate with increased precipitation, evaporation and runoff production ascompared with recent climate, but would be still likely prone to water shortages in the period of 2031-2070. In addition,under future climate A2 and B2, an increase in runoff during the wet season was noticed, indicating a future rise in theflood occurrence possibility in the Haihe River Basin.
基金Project(2020YFF0426370) supported by the National Key Research and Development Program of ChinaProject(SF-202010) supported by the Water Conservancy Technology Demonstration,China。
基金sponsored by College of Water Resources and Enviroment,Hohai University,Nanjing,China.
文摘The study area was designed and constructed, based on the simplification of aconceptual model, to develop a three-dimensional groundwater flow model for simulation oftwo-layers system. Finite difference groundwater flow model was constructed for the CentralSonghuajiang River alluvial plain in Northeast China, with the coverage of 786. 6km^2. The gridnetworks with a spacing of 474. 4m by 509. 5m were used to cover the model area. The trial-and-errortechnique was used to calibrate the model. The sensitivity of the simulations to the modelparameters was studied -and the most sensitive parameters that controlling the residual headsdistribution in the Songhuajiang River valley were defined.
基金The authors would like to acknowledge the funding support of the National Natural Science Foundation of China (No. 50579009, 70425001).
文摘Precise comprehensive evaluation of flood disaster loss is significant for the prevention and mitigation of flood disasters. Here, one of the difficulties involved is how to establish a model capable of describing the complex relation between the input and output data of the system of flood disaster loss. Genetic programming (GP) solves problems by using ideas from genetic algorithm and generates computer programs automatically. In this study a new method named the evaluation of the grade of flood disaster loss (EGFD) on the basis of improved genetic programming (IGP) is presented (IGP-EGFD). The flood disaster area and the direct economic loss are taken as the evaluation indexes of flood disaster loss. Obviously that the larger the evaluation index value, the larger the corresponding value of the grade of flood disaster loss is. Consequently the IGP code is designed to make the value of the grade of flood disaster be an increasing function of the index value. The result of the application of the IGP-EGFD model to Henan Province shows that a good function expression can be obtained within a bigger searched function space; and the model is of high precision and considerable practical significance. Thus, IGP-EGFD can be widely used in automatic modeling and other evaluation systems.
文摘It is important and necessary to get a much longer precipitation series in order to research features of drought/flood and climate change. Based on dryness and wetness grades series of 18 stations in Northern China of 533 years from 1470 to 2002, the Moving Cumulative Frequency Method (MCFM) was developed, moving average precipitation series from 1499 to 2002 were reconstructed by testing three kinds of average precipitation, and the features of ell mate change and dry and wet periods were researched by using reconstructed precipitation series in the present paper. The results showed that there were good relationship between the reconstructed precipitation series and the observation precipiration series sincc 1954 and their relative root mean-square error were below 1.89%, that the relation between reconstructed series and the dryness and wetness grades series were nonlinear and this nonlinear relation implied that reconstructed series were reliable and could became foundation data for researching evolution of the drought and flood. Analysis of climate change upon reconstructed precipitation series revealed that although drought intensity of recent dry period from mid- dle 1970s of 20th century until early 21st century was not the strongest in historical climate of Northern China, intensity and duration of wet period was a great deal decreasing and shortening respectively, climate evolve to aridification situa- tion in Northern China.
基金Project supported by the Ministry of Science and Technology in China (Grant No: 2002DIB20067)
文摘Evaporation plays an important role in water balance on the land surface. In Northern China, the evaporation series of the recent 115 years was reconstructed on the basis of Yhornthwaite evaporation formula. The characteristics of the reconstructed series were analyzed using 10-year running mean filter, power spectrum method, and running t-text of abrupt changes on the paper. The results showed that there were remarkable interannual fluctuations with timescales of about quasi-8-year, 3-4-year, and quasi-2-year, and interdecadal oscillations with timescales of 57.5-year, quasi-23-year, and l l.5-year. Meanwhile, the abrupt changes of the evaporation series were also of interdecadal timescale. Either interannual fluctuations or interdecadal oscillations of evaporation were closely related to variations in air temperatures and precipitation.
文摘To improve the Xinanjiang model, the runoff generating from infiltration excess is added to the model. The another 6 parameters are added to Xinanjiang model. In prin ciple, the improved Xinanjiang model can be used to simulate runoff in the humid, semi-humid and also semi-arid regions. The application in Yi River shows the improved Xinanjiang model could forecast discharge with higher acetrracy and can satisfy the practical requirements,It also shows thai the improved model is reasonable.