Gully erosion is serious in the tableland area of the Loess Plateau due to high-intensity human activities and extreme rainfall, which cause serious soil loss and an increasing tableland shrinkage rate. Severe gully e...Gully erosion is serious in the tableland area of the Loess Plateau due to high-intensity human activities and extreme rainfall, which cause serious soil loss and an increasing tableland shrinkage rate. Severe gully erosion has exerted a notable negative impact on local agriculture, human life and socioeconomic development. In recent decades, progress has been made in soil and water conservation with the goal of reducing soil erosion and protecting loess tableland, but basic research on gully consolidation and tableland protection(GCTP) is lacking, especially regarding the mechanisms of gully erosion and expansion in loess tableland under the interactive impacts of hydrodynamics and human activities. In addition, there is a lack of a deep understanding of the underlying mechanisms of soil-water disasters and controlling factors of unreasonable GCTP projects.Currently, the problems of headcut erosion and tableland fragmentation remain serious. Based on this situation, the Dongzhi tableland, the largest tableland on the Loess Plateau, was adopted as an example, and we studied gully erosion and expansion mechanisms in the loess tableland and the scientific basis of GCTP projects. We obtained a series of novel findings, including the following:(1) vertical joints are widely developed in loess and impose a controlling effect on tableland edge erosion;(2) rapid urbanization and road network expansion intensify headcut erosion and are the main reasons for severe erosion and tableland shrinkage in the Dongzhi tableland;and(3) unreasonable drainage of surface runoff and a rise in the groundwater level are the key factors affecting GCTP project stability. Moreover, the mechanisms and modes of erosion disasters in the project driven by these two factors were explained. The systematic remediation idea of retention, storage, drainage and consolidation for the GCTP project was introduced, and the core is water control, which emphasizes the combination of soil and water conservation and geohazard prevention measures. As a systematic remediation project, GCTP in loess tableland requires multidisciplinary and multimethod approaches and multiple measures involving ecology, soil and water conservation, geology and engineering to ensure project feasibility and sustainability.展开更多
Drainage divides along a southern Laramie Range crest area and in the nearby southeast Wyoming Gangplank area (as observed on detailed topographic maps) suggest present-day drainage routes in the Cheyenne Tablelands r...Drainage divides along a southern Laramie Range crest area and in the nearby southeast Wyoming Gangplank area (as observed on detailed topographic maps) suggest present-day drainage routes in the Cheyenne Tablelands region originated as headward erosion of south-oriented valleys (now the downstream Lodgepole, Crow, and Lone Tree Creek valleys) from an actively eroding northeast-oriented South Platte River valley captured flood flow in the south half of a large east-oriented anastomosing channel complex while headward erosion of a north-oriented valley (now the downstream Horse Creek valley) from the southeast-oriented North Platte River valley captured the north half of the same large anastomosing channel complex. The Gangplank, which today serves as a low gradient ramp of Tertiary Ogallala Formation sediments leading from the Great Plains to the Laramie Range erosion surface, is located along the Crow Creek-Lone Tree Creek drainage divide and low points along that divide (referred to here as divide crossings) suggest, prior to headward erosion of what is now its south-oriented downstream Lone Tree Creek valley, upstream east-oriented Lone Tree Creek drainage routes were intertwined with east-oriented Crow Creek drainage routes, which today flow much further in an east direction (than east-oriented upstream Lone Tree Creek drainage routes) before also turning in a south direction to reach the South Platte River. The ability of the commonly accepted regional geomorphology paradigm to explain this topographic map evidence is then compared with a fundamentally different and new regional geomorphology paradigm’s ability to explain the same evidence. While both paradigms offer possible explanations the new paradigm, which requires headward erosion of the valleys to have occurred as massive continental ice sheet melt water floods crossed the region, explains much more of the drainage system evidence and also permits much more detailed explanations.展开更多
Focused on the rainfall characteristics and the reality of agricultural production in the loess tableland , and based on previous results, new patterns for dryland winter wheat production, in which the emphasis was pu...Focused on the rainfall characteristics and the reality of agricultural production in the loess tableland , and based on previous results, new patterns for dryland winter wheat production, in which the emphasis was put on the film mulch with obvious water-preserving advantage, were designed to make effective use of rainfall. The results showed that the technique of the double mulch of film plus straw in summer fallow period can collect the rainfall in this period to the utmost extent and over 73.2% of it can be stored in the soil, which is 108. 4 mm more than that of conventional tillage. Furthermore, it can not only preserve water stored in soil in summer fallow, but also collect the rainfall in the growth period as much as possible by using the technique of making ridges plus film mulching and furrow sowing. So the patterns, which can greatly increase both the soil moisture and wheat yield, are the best choice for making full utilization of the rainfall and achieving a high and stable yield in the dryland wheat production of the loess tableland.展开更多
Road network expansion can result in the fragmentation of ecological landscapes due to the transformation of landscape processes and patterns.However,knowledge about these processes and patterns is scarce.In this stud...Road network expansion can result in the fragmentation of ecological landscapes due to the transformation of landscape processes and patterns.However,knowledge about these processes and patterns is scarce.In this study,the road network and landscape patterns in the Dongzhi tableland of the Chinese Loess Plateau(CLP) between 2005 and 2020 were characterized,and their spatial relationships were analyzed.The results showed that(1) the kernel density estimation(KDE) method is useful in characterizing road network density.When the bandwidth value is four,the boundary of the road network kernel can be distinguished clearly.(2) The road network in the tableland expanded greatly over the past 15 years,and the total area of road kernels in the Dongzhi tableland increased from 55.73 km~2 in 2005 to 223.55 km~2 in 2020.(3) High-density road networks were generally distributed on cultivated and constructed lands where the slopes were generally 0°–5°,while low-and medium-density road networks were mostly distributed in grassland areas where the slopes were greater than 5°.(4) Road network density is closely related to the coverage of cultivated and constructed lands.The results of this study are helpful in understanding the potential impact of road network evolution on the landscape at a regional scale.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41790444)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB40000000)。
文摘Gully erosion is serious in the tableland area of the Loess Plateau due to high-intensity human activities and extreme rainfall, which cause serious soil loss and an increasing tableland shrinkage rate. Severe gully erosion has exerted a notable negative impact on local agriculture, human life and socioeconomic development. In recent decades, progress has been made in soil and water conservation with the goal of reducing soil erosion and protecting loess tableland, but basic research on gully consolidation and tableland protection(GCTP) is lacking, especially regarding the mechanisms of gully erosion and expansion in loess tableland under the interactive impacts of hydrodynamics and human activities. In addition, there is a lack of a deep understanding of the underlying mechanisms of soil-water disasters and controlling factors of unreasonable GCTP projects.Currently, the problems of headcut erosion and tableland fragmentation remain serious. Based on this situation, the Dongzhi tableland, the largest tableland on the Loess Plateau, was adopted as an example, and we studied gully erosion and expansion mechanisms in the loess tableland and the scientific basis of GCTP projects. We obtained a series of novel findings, including the following:(1) vertical joints are widely developed in loess and impose a controlling effect on tableland edge erosion;(2) rapid urbanization and road network expansion intensify headcut erosion and are the main reasons for severe erosion and tableland shrinkage in the Dongzhi tableland;and(3) unreasonable drainage of surface runoff and a rise in the groundwater level are the key factors affecting GCTP project stability. Moreover, the mechanisms and modes of erosion disasters in the project driven by these two factors were explained. The systematic remediation idea of retention, storage, drainage and consolidation for the GCTP project was introduced, and the core is water control, which emphasizes the combination of soil and water conservation and geohazard prevention measures. As a systematic remediation project, GCTP in loess tableland requires multidisciplinary and multimethod approaches and multiple measures involving ecology, soil and water conservation, geology and engineering to ensure project feasibility and sustainability.
文摘Drainage divides along a southern Laramie Range crest area and in the nearby southeast Wyoming Gangplank area (as observed on detailed topographic maps) suggest present-day drainage routes in the Cheyenne Tablelands region originated as headward erosion of south-oriented valleys (now the downstream Lodgepole, Crow, and Lone Tree Creek valleys) from an actively eroding northeast-oriented South Platte River valley captured flood flow in the south half of a large east-oriented anastomosing channel complex while headward erosion of a north-oriented valley (now the downstream Horse Creek valley) from the southeast-oriented North Platte River valley captured the north half of the same large anastomosing channel complex. The Gangplank, which today serves as a low gradient ramp of Tertiary Ogallala Formation sediments leading from the Great Plains to the Laramie Range erosion surface, is located along the Crow Creek-Lone Tree Creek drainage divide and low points along that divide (referred to here as divide crossings) suggest, prior to headward erosion of what is now its south-oriented downstream Lone Tree Creek valley, upstream east-oriented Lone Tree Creek drainage routes were intertwined with east-oriented Crow Creek drainage routes, which today flow much further in an east direction (than east-oriented upstream Lone Tree Creek drainage routes) before also turning in a south direction to reach the South Platte River. The ability of the commonly accepted regional geomorphology paradigm to explain this topographic map evidence is then compared with a fundamentally different and new regional geomorphology paradigm’s ability to explain the same evidence. While both paradigms offer possible explanations the new paradigm, which requires headward erosion of the valleys to have occurred as massive continental ice sheet melt water floods crossed the region, explains much more of the drainage system evidence and also permits much more detailed explanations.
基金This study was supported by the National High-Tech Research and Development Plan(the“863”Plan of China,2002AA2Z4021)the National Natural Science Foundation of China(30070439)the National Key Project for the"Ninth Five Year"Plan,China(96-004-05-08).
文摘Focused on the rainfall characteristics and the reality of agricultural production in the loess tableland , and based on previous results, new patterns for dryland winter wheat production, in which the emphasis was put on the film mulch with obvious water-preserving advantage, were designed to make effective use of rainfall. The results showed that the technique of the double mulch of film plus straw in summer fallow period can collect the rainfall in this period to the utmost extent and over 73.2% of it can be stored in the soil, which is 108. 4 mm more than that of conventional tillage. Furthermore, it can not only preserve water stored in soil in summer fallow, but also collect the rainfall in the growth period as much as possible by using the technique of making ridges plus film mulching and furrow sowing. So the patterns, which can greatly increase both the soil moisture and wheat yield, are the best choice for making full utilization of the rainfall and achieving a high and stable yield in the dryland wheat production of the loess tableland.
基金National Natural Science Foundation of China,No.41790444Strategic Priority Research Program of Chinese Academy of Sciences,No.XDB40000000National Key Research and Development Program,No.2018YFC1504701。
文摘Road network expansion can result in the fragmentation of ecological landscapes due to the transformation of landscape processes and patterns.However,knowledge about these processes and patterns is scarce.In this study,the road network and landscape patterns in the Dongzhi tableland of the Chinese Loess Plateau(CLP) between 2005 and 2020 were characterized,and their spatial relationships were analyzed.The results showed that(1) the kernel density estimation(KDE) method is useful in characterizing road network density.When the bandwidth value is four,the boundary of the road network kernel can be distinguished clearly.(2) The road network in the tableland expanded greatly over the past 15 years,and the total area of road kernels in the Dongzhi tableland increased from 55.73 km~2 in 2005 to 223.55 km~2 in 2020.(3) High-density road networks were generally distributed on cultivated and constructed lands where the slopes were generally 0°–5°,while low-and medium-density road networks were mostly distributed in grassland areas where the slopes were greater than 5°.(4) Road network density is closely related to the coverage of cultivated and constructed lands.The results of this study are helpful in understanding the potential impact of road network evolution on the landscape at a regional scale.
