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The Yellow River Basin is geographically critical to protect the ecological environment in China. But there is a large demand for agriculture, rapid economy as well as ecological and environmental pressure in the Yellow River Basin, especially in the Middle Reaches of the Yellow River (MRYR) at present. An ecological security pattern (ESP) is also very urgent to clarify the ecological bottom line and areas for restoration, in order to maintain a green ecological protection barrier. Taking MRYR as the study area, this study aims to construct a scientific ESP for the restoration and protection of the ecological environment. Firstly, the core area was calculated using morphological spatial pattern analysis. The national nature reserve was also superimposed to screen the ecological sources. Secondly, a comprehensive system was constructed for the resistance surface indicator. Then the circuit theory model was used to identify the ecological corridors, ecological pinch points, and barrier areas. The ESP of MRYR was constructed to obtain the dynamic trends and features of ESP from 2000 to 2020. Finally, some strategies were proposed to optimize the ESP for ecological and environmental protection, according to specific ecological conditions. The results showed that the number and area of ecological sources remained basically stable. The eastern basin and mountains were distributed densely, while the western plateau was distributed more sparsely. The number of ecological corridors evolved from 96 in 2000 to 103 in 2020. There was a dense distribution in the eastern part of the country, where the mountains were widespread. While in the western part of the country, the ecological corridors were sparse and spanned longer distances. The area of ecological pinch points remained stable. A slight decreasing trend was observed in the area of barrier areas. The pinch points and barrier areas were most densely distributed in the connecting area of the source and the corridor and in the middle of the corridor. The ESP presented a dense spatial pattern in the southeast, while the sparse spatial pattern in the northwest. Pinch-point protection areas were changed frequently in the sparse western corridors. The barrier restoration areas were concentrated in the basins or plains with high human activity intensities. The sparse source-protected areas required stable "staging areas" to maintain corridor connectivity over long distances. The number and length of corridors showed an increasing trend. The ESP shared the promising potential during this time. The spatial difference in the ESN between the eastern and western parts of the MRYR was attributed to the combination of high-intensity human activities and ecologically sound mountainous areas concentrated in the eastern part of the region, and fragile ecological environments and irrational development activities in the western part of the region. According to the specific ESP and the actual ecological situation in the region, some measures were proposed to restore and protect the ecological sources, and corridor elements. The finding can provide a strong reference to optimize the ESP in MRYR, particularly for the high-quality development of the ecological environment. [ABSTRACT FROM AUTHOR]

An accurate assessment of the spatial–temporal variations in regional net ecosystem productivity (NEP), water use efficiency (WUE), and carbon use efficiency (CUE) are vital for understanding the water–carbon cycle. We analyzed the spatial–temporal patterns of the NEP, WUE, and CUE in the middle reaches of the Yellow River (MRYR) from 2001 to 2022, and the factors that influenced them using remote sensing data, NEP estimation models, and various statistical methods. The results indicate that the recovery of the ecosystem in the MRYR is a result of the combined effects of climate change and human activities. Climate change in the MRYR led to warming and humidification from 2001 to 2022. The NEP, WUE, and CUE were characterized by increasing trends, with average growth rates of 7.75 gC m−2a−1, 0.012 gC m−2 mm−1a−1, and 0.009a−1, respectively. For four vegetation types, the interannual rates of change were, in descending order, grassland, cropland, shrubs, and forest. Spatially, the NEP, WUE, and CUE showed significant regional heterogeneity, increasing from the northwest to the southeast. Based on an analysis of the interannual anomalies, precipitation accumulation contributed to carbon sink accumulation. The correlation of the NEP, WUE, and CUE with the drought severity index (DSI) was high, and their correlation with precipitation showed latitudinal zonality, which suggests that precipitation (PRE) is the main climatic factor influencing the water–carbon cycle in the MRYR rather than temperature (TEM). There were 67,671.27 km2 of land that changed use during 2001–2022, and 15.07 Tg of NEP was added to these areas. [ABSTRACT FROM AUTHOR]

Frequent soil erosion disasters in the middle reaches of the Yellow River (MRYR) have a profound effect on the sediment load of the river. This paper addresses the intertwined effects of human activities and climate change on river runoff and sediment load. Therefore, runoff and sediment loads from hydrological stations along the main and tributary rivers within the MRYR were used. The Mann–Kendall (M–K) trend test and the double mass curve analysis, among other analytical tools, were used to examine the erosion patterns of these rivers from 1950 to 2022, as well as the main factors driving these changes. The results showed that the runoff depth of the Yan River tended to decrease, and there was a significant decrease in the mainstream and nine other tributaries, with a significant decrease in the sediment transport modulus for both the mainstream and tributaries. In the main river, human activities contributed between 69.99% and 94.69% to the runoff and between 88.52% and 98.49% to the sediment load, while in the tributaries, the contribution of human activities was greater. The annual runoff and annual sediment load in the MRYR showed a decreasing trend, with a discernible impact of human activities. The results of this research are of great significance for erosion control and the restoration of the ecological balance in the Yellow River Basin. [ABSTRACT FROM AUTHOR]

Jujube (Ziziphus jujuba Mill.) makes up a traditional characteristic industry with ecological significance in the Lüliang Mountain of middle reaches of the Yellow River (LMMRYR). However, low economic efficiency has reduced local farm households' willingness to continue jujube cultivation, threatening the sustainable maintenance and development of jujube forests and the ecological environment. In response, Lüliang City implemented a technological innovation program, that is, the Jujube Forest High Grafting and Optimization Program (JFHGOP), in 2018. Based on survey data from 302 local farm households, an empirical analysis using propensity score matching and ordinary least squares methods revealed that the program significantly enhanced the economic, ecological, and social benefits for participating farm households, improving their overall welfare. Robustness tests confirmed these findings, and a heterogeneity analysis showed varied impacts across different dimensions. The program improved welfare through government support and cooperatives' assistance. To further promote green development and farm households' welfare, recommendations include advancing forestry innovation technology, supporting small farm households with policy, capital, and technology, optimizing subsidy mechanisms, supporting new business entities, and promoting cooperation and benefit-sharing among stakeholders. [ABSTRACT FROM AUTHOR]

The extreme characteristics and formation mechanism of the sustained heavy rainfall process in the middle reaches of the Yellow River from July to August 2022 were analyzed in detail using precipitation observation data from national and provincial meteorological stations， ERA5 reanalysis data from the European Medium Range Weather Forecast Center， and terrain elevation data from the National Environmental Information Center of the United States.The results indicate that： （1） a total of 11 heavy precipitation processes occurred in the middle reaches of the Yellow River during the research period， characterized by long duration， large cumulative rainfall， short precipitation time intervals， and high overlap of heavy rainfall areas.The standardized anomaly of accumulated precipitation at 18 stations exceeds 2.5， the maximum hourly rainfall intensity exceeds 50 mm/h during multiple processes， exhibiting significant extreme characteristics， and the extreme of precipitation is stronger in August than that in July.The distribution of heavy rain bands is closely related to the topographic characteristics of the middle reaches of the Yellow River.（2） From July to August， the standardized anomaly near Lake Baikal in mid to high latitudes Asia reached -2.5 to -1.5 （Exceeding -3.5 in August）， and the low trough is abnormally strong compared to the same period in previous year.During processes of heavy precipitation， the western ridge of the subtropical high is in a westward moving state.The ridge line of the subtropical high and the north-south boundary of the northern boundary have a large swing in July.Each north-south oscillation of the subtropical high combines with cold air from Lake Baikal， triggering a series of heavy precipitation processes.The ridge line and northern boundary of the subtropical high slowly retreat to the south in August with a small amplitude， and persistent heavy precipitation occurred at the edge of the subtropical high.（3） The water vapor come from the Bay of Bengal， South China Sea， and East China Sea， with an integrated standardized anomaly of 2.5 for the entire layer of water vapor flux in August.PWAT maintains 40~60 mm， with its standardized anomaly ranging from 2.5 to 3.5 in the southern part of Inner Mongolia and the northern part of the Shaanxi region， locally exceeding 3.5.The water vapor conditions are significantly stronger in August than in July.（4） There is an unstable stratification above the middle reaches of the Yellow River， characterized by upper dry cold and lower warm wet.Frontogenesis is formed north of 36°N in the middle and lower layers， and the upward movement occurs throughout the northern layer.The vertical velocity standardization anomaly reaches -2.5 to -0.5， which is corresponding to strong precipitation area.（5） The analysis of frontogenesis function in August shows that there were frontogenesis before and during the occurrence of precipitation in the northern part of the middle reaches of the Yellow River.The increase and decrease in frontogenesis values are consistent with the trend of precipitation intensity variations.The deformation term contributes significantly to the total frontogenesis， while the tilt term contributes significantly to the total dissipation.The process with high precipitation intensity results in higher frontogenesis extension height， while the process with low intensity results in lower frontogenesis height and relatively smaller frontogenesis value.

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Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The partial pressure of CO2 in rivers regulates the intensity and direction of carbon dioxide (CO2) exchange at the water–air interface. Environmental, nutrient factors, and their stoichiometric ratios within the watershed may affect the level of carbon dioxide partial pressure in rivers. However, the relationship between pCO2 responses to the environment, nutrient factors, and their stoichiometric ratios at a large watershed scale was not well understood. In this study, water samples from 20 locations in the mainstream and 16 tributaries of the middle reaches of the Yellow River were collected to study the spatial characteristics of pCO2 and its influencing factors. pCO2 vales showed spatial heterogeneity ranging from 45.57 to 3631.48 μatm, and an average of 1341.87 μatm. Relative to the atmospheric equilibrium value (415 μatm), 90% of the samples were supersaturated. During the study period, higher pCO2 appeared in the Wanjiazhai Reservoir at the northernmost part of the mainstream in the middle reaches, and in the tributaries of the Fen, Wei, and Beiluo Rivers. Overall, the transition from carbon sink to carbon source was experienced in the middle reaches of the Yellow River from north to south. River pCO2 exhibited a significant correlation with phosphorus concentrations and their associated stoichiometric ratio, suggesting that microbial metabolism drove CO2 saturation in rivers. In addition, different land use proportions contributed significantly to changes in river pCO2. [ABSTRACT FROM AUTHOR]

[Objective] The spatio-temporal coupling coordination relationship between high-quality development and water resource conservation and utilization in the urban agglomerations of the middle reaches of the Yellow River in order to provide decision support and a scientific basis for the sustainable use of water resources and effective protection of water ecology in the region. [Methods] Based on the panel data of high-quality development and water resources protection and utilization in 19 cities in the middle reaches of the Yellow River from 2011 to 2021, the coupling coordination degree of high-quality development and water resources protection and utilization and its spatio-temporal characteristics were analyzed by means of combination weighting, coupling coordination degree model and a geographic detector model. [Results] The level of high-quality development and water resource conservation and utilization in the urban agglomeration of the middle reaches of the Yellow River had improved continuously, and regional disparity has gradually narrowed. The coupling coordination degree of the two systems increased over time, with some areas transitioning from the brink of imbalance to the initial stage of coordination. Furthermore, the coupling coordination degree exhibited positive spatial autocorrelation, radiating outward from the two central cities of Xi’an and Zhengzhou City. The degree of dependence on foreign trade and the proportion of tertiary industry output had significant impacts on the coordination of the two systems, with nonlinear enhancement or mutual strengthening relationships among interactive factors. [Conclusion] To enhance the spatial dependence of high-quality development and water resource conservation and utilization in urban agglomerations of the middle reaches of the Yellow River, it will be necessary to strengthen regional cooperation, optimize water resource utilization structures, improve water resource management capabilities, increase investment in science and technology, enhance regional innovation capacity, and actively promote coordinated regional development.

Frequent soil erosion disasters in the middle reaches of the Yellow River (MRYR) have a profound effect on the sediment load of the river. This paper addresses the intertwined effects of human activities and climate change on river runoff and sediment load. Therefore, runoff and sediment loads from hydrological stations along the main and tributary rivers within the MRYR were used. The Mann–Kendall (M–K) trend test and the double mass curve analysis, among other analytical tools, were used to examine the erosion patterns of these rivers from 1950 to 2022, as well as the main factors driving these changes. The results showed that the runoff depth of the Yan River tended to decrease, and there was a significant decrease in the mainstream and nine other tributaries, with a significant decrease in the sediment transport modulus for both the mainstream and tributaries. In the main river, human activities contributed between 69.99% and 94.69% to the runoff and between 88.52% and 98.49% to the sediment load, while in the tributaries, the contribution of human activities was greater. The annual runoff and annual sediment load in the MRYR showed a decreasing trend, with a discernible impact of human activities. The results of this research are of great significance for erosion control and the restoration of the ecological balance in the Yellow River Basin.

An accurate assessment of the spatial–temporal variations in regional net ecosystem productivity (NEP), water use efficiency (WUE), and carbon use efficiency (CUE) are vital for understanding the water–carbon cycle. We analyzed the spatial–temporal patterns of the NEP, WUE, and CUE in the middle reaches of the Yellow River (MRYR) from 2001 to 2022, and the factors that influenced them using remote sensing data, NEP estimation models, and various statistical methods. The results indicate that the recovery of the ecosystem in the MRYR is a result of the combined effects of climate change and human activities. Climate change in the MRYR led to warming and humidification from 2001 to 2022. The NEP, WUE, and CUE were characterized by increasing trends, with average growth rates of 7.75 gC m−2a−1, 0.012 gC m−2 mm−1a−1, and 0.009a−1, respectively. For four vegetation types, the interannual rates of change were, in descending order, grassland, cropland, shrubs, and forest. Spatially, the NEP, WUE, and CUE showed significant regional heterogeneity, increasing from the northwest to the southeast. Based on an analysis of the interannual anomalies, precipitation accumulation contributed to carbon sink accumulation. The correlation of the NEP, WUE, and CUE with the drought severity index (DSI) was high, and their correlation with precipitation showed latitudinal zonality, which suggests that precipitation (PRE) is the main climatic factor influencing the water–carbon cycle in the MRYR rather than temperature (TEM). There were 67,671.27 km2 of land that changed use during 2001–2022, and 15.07 Tg of NEP was added to these areas.

Copyright of Bulletin of Soil & Water Conservation is the property of Bulletin of Soil & Water Conservation Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Objective] In order to provide a reference for the thorough control of watershed soil erosion and the improvement of ecological environment quality in the Loess Plateau region, the effects of ecological engineering measures and natural factors on soil erosion evolution were revealed, and the inhibition degrees of engineering factors and hydrological factors on soil erosion were quantified. [Methods] Based on the rainfall data of 77 meteorological stations in the middle reaches of the Yellow River, land use types, vegetation coverage, digital elevation model, soil texture and other data of four periods in the basin, the RUSEL model and geographic detector method were used to study the spatiotemporal changes and driving factors of soil erosion by extracting precipitation, topography, climate, soil and land use in the basin. [Results] The largest reduction in sediment erosion in the Yellow River′s middle sections between 2000 and 2010 was observed. Soil loss significantly reduced due to ecological engineering at altitudes between 1 000 and 1 500 m, at slope gradients between 8° and 15°, and on hillsides that were both semi-shaded and semi-sunny. The capacity of soil and water loss control decreased in the order: forestland＞grassland＞cultivated land, and the erosion area changed most dramatically in the range of 30%～50% vegetation coverage, which was the key restoration and reconstruction area of the project of converting farmland to forest. In the middle reaches of the Yellow River, rainfall increased gradually from northwest to southeast over the years, and the spatial vertical difference changes under the influence of topography, and the interannual fluctuation increased insignificantly, which had the potential to aggravate soil erosion. Vegetation coverage increased linearly, and its increment increased from northwest to southeast. Vegetation coverage was the main controlling factor affecting soil erosion. In the middle Yellow River, the interaction between vegetation coverage and the slope was the strongest, and the synergistic effects of vegetation coverage, slope and other factors could significantly enhance the force on soil erosion pattern evolution. [Conclusion] In the middle reaches of the Yellow River, the land use pattern was dominated by agriculture and animal husbandry for a long time, and the cultivated land with steep slopes flowed continuously to the forest and grassland with high topographic adaptability and elasticity over the years, reflecting that the core part of the national farmland conversion project is to convert sloping land into forest and grassland. The ecological engineering mainly characterized by vegetation cover change dominated the process and degree of soil erosion reduction in the middle Yellow River, and the driving force of the interaction of any two factors was greater than that of a single factor. [ABSTRACT FROM AUTHOR]

[Objective] This study aims to explore the evolution process and driving factors of land use landscape in Kuye River Basin from 1980 to 2020, and to provide reference for the management and high-quality development of ecosystem in the whole Yellow River Basin. [Methods] Landsat series remote sensing data were selected as the data source, and the characteristics of land use landscape pattern change in the Kuoye River Basin were analyzed by landscape ecology and GIS spatial analysis. Combined with climate data and socioeconomic data, the driving factors of land use landscape pattern evolution in Kuye River Basin were discussed. [Results] The cultivated land area in the Kuye River Basin decreased from 1 677.92 km 2 in 1980 to 1 365.58 km 2 in 2020. The grassland area decreased from 5 144.35 km 2 in 1980 to 5 038.97 km 2 in 2020. The forestland area and construction land area increased by 86.07 km 2 and 798.96 km 2, respectively, while the water area and unused land area decreased by 60.25 km ² and 408.72 km ², respectively. From 1980 to 2020, the transfer of land use types was mainly from unused land to arable land and grassland, accounting for 8.63% and 61.47% of the reduction of unused land area. Arable land, grassland and unused land transferred to construction land accounted for 23.07%, 50.98% and 10.95% of the increase of construction land area, and the intensity of land use type transfer from 2000 to 2020 was higher than that from 1980 to 2000. The landscape patches in the watershed showed the characteristics of increasing the number of patches, decreasing the degree of connectedness, increasing the degree of fragmentation, increasing the degree of segmentation, decreasing the degree of cohesion and increasing the complexity. [Conclusion] Climate change and human activities are both the influencing factors of landscape pattern evolution in Kuye River Basin, among which the increasing human activities are the main factor promoting landscape pattern evolution, while climate change is the secondary factor. [ABSTRACT FROM AUTHOR]

[Objective] Based on different models, the spatiotemporal evolution characteristics of rainfall erosivity in the middle reaches of the Yellow River were explored, in order to providing a reference basis for the assessment of soil erosion hazards and planning of soil and water conservation measures in this area. [Methods] Daily rainfall data from 1981 to 2020 for the middle reaches of the Yellow River was used to explore the temporal and spatial variation characteristics of rainfall and rainfall erosivity based on two rainfall erosivity models. [Results] Average annual rainfall in the middle reaches of the Yellow River was between 349.90 mm and 699.90 mm. Spatial variation followed a fluctuating decreasing trend from southeast to northwest. Temporal variation exhibited a multi-peak insignificant upward fluctuation that had a 2-year main cycle change feature. There were some similarities between the two models of rainfall erosivity from the interannual trend characteristics and periodicity in the middle reaches of the Yellow River. However, areas with greater rainfall exhibited greater differences in rainfall erosivity estimated by the two models. The average annual rainfall erosivity in the middle reaches of the Yellow River was 767.00~3 003.40 MJ·mm/(hm2·h), exhibiting a high monthly concentration (concentrated in July-August) and showing a single peak shape. [Conclusion] There were significant vertical spatial differences from annual average rainfall erosivity in the middle reaches of the Yellow River, and there were spatial differences resulting from the influence of topography and landforms. The coefficient of variation in high-altitude areas was generally greater than in low-altitude areas. In the Qinling Mountains and the Guanzhong Plain in the southeast, the erosivity of rainfall decreased rapidly with increasing altitude. In in the northwest of the Loess Plateau region, the erosivity of rainfall increased gradually with increasing altitude. Therefore, in areas where erosivity of rainfall increases in the middle reaches of the Yellow River, appropriate measures should be taken to reduce the potential risk of soil erosion and to ensure the sustainable development of regional ecological security.

A land resource asset (LRA) table is highly valued by the Chinese government for resource management. However, most of China's researches on LRA table focused on theoretical construction. The difficulty in obtaining data hinders the practice and promotion of existing methods, and it limits the selection of data for many practical studies. Thus, this study proposes a land value quantification (LVQ) model that is suitable for a large spatio–temporal scale background to solve the above problems. Based on this model, the LRA table in the middle reaches of the Yellow River was successfully compiled. The results indicated that: (1) the assets of regional land resources were in an unbalanced development state; (2) the LRAs in the middle Yellow River had changed frequently; (3) there were significant spatial differences in the distributions of various types of LRAs in the middle reaches of the Yellow River; and (4) topography and soil erosion were the main factors restricting optimal regional land resource spatial allocation. Based on the research findings, this study provides scientific policy recommendations for the optimal allocation and sustainable development of land resources in the middle reaches of the Yellow River. Moreover, the LVQ model proposed in this research provides a model reference for LRA accounting with large spatial and temporal scales in China and similar regions. [ABSTRACT FROM AUTHOR]

[Objective] River evolution is the result of the interaction between river flow and riverbed boundaries, and has a significant impact on the safety of water projects and the prevention and control of flooding. The Fugu-Longmen section of the middle reaches of the Yellow River is located in the J in-Shan canyon, and is dominated by gully erosion land form of the Loess Plateau. Riverbank erosion is the main source of sediment in this area. So it is important to study the characteristics and influencing factors of river channel souring and silting in this section to control soil erosion in the middle reaches of the Yellow River. Met hods] Based on data of runoff, sediment and river cross-sect ion in three typical hyd rological stations, Fugu, W ubu and Longmen, the characteristics of channel erosion and siltation, and the related influencing factors in Fugu-Longmen section from 2007 to 201 7 were analysed. Results] (1) The channel exhibited erosion in Fugu-Longmen section in the past 11 years, with the channel in Fugu-Wubu section exhibiting a gradual decrease and the channel exhibiting an increase in Wubu-Longmen section. (2) The Fugu-Wubu section showed a trend of decreasing water and increasing sediment, while the Wubu-Longmen section showed an overall trend of more water and less sediment. The amount of channel erosion and siltation in the two sections was synchronized with the change of sediment content in the water flow. (3) The median size of suspended sediment in the Fugu-Wubu section increased, then river scour became slower. The median size of suspended sediment in the Wubu-Longmen section tended to decrease, exacerbating river erosion. (4) The amount of incoming yellow sediment in the Fugu-Wubu section increased, the erosive force of the river weakened, and river scouring became slower. The Wubao-Longmen section was in a state of scouring due to human intervention, which reduced the amount of sediment entering the Yellow River and increased the erosive force of the river. These results are consistent with the pattern of channel evolution in both river sections. Con elusion] The change of runoff and sediment have greatly affected the siltation of the Fugu-Longmen section. Under the background of improved ecological environment, it is significance to study the characteristics and dynamic mechanism of river channel dredging in this section of the river to further reduce soil erosion in the middle reaches of the river and prevent flood disasters in the middle and lower reaches of the river. [ABSTRACT FROM AUTHOR]

The middle reaches of the Yellow River is an important national ecological function area and energy base. It is an arduous task to prevent and control soil erosion and protect ecology. In view of the problems of large quantity of soil and water conservation supervision work area, insufficient supervision ability and weak timeliness of traditional supervision way in the Yellow River Basin, this paper puts forward some countermeasures for establishing the pilot demonstration zone of high quality supervision of soil and water conservation in the contiguous area of Shanxi, Shaanxi and Inner Mongolia, and probes into its working mechanism and mode: First, the goal of innovation management is to take the lead in implementing non-violation projects, Second, the goal of innovation cooperation is to jointly build a working system, and build a working mechanism with consistent goals, self-awareness of actions, and coordinated efforts, Third, the endogenous motivation of innovation, taking self-discipline as the core to promote the overall level of credit for soil and water conservation, Fourth, leaders at all levels, construction units, young people and the general public should improve the cognition and ability of ecological civilization in soil and water conservation to achieve the unity of knowledge and practice, Fifth, the connotation of innovation evaluation will be improved to comprehensively enhance the level of scientific and technological support, Sixth, digital empowerment, scientific classified management and innovative smart platform will enable production and construction projects to achieve smart technology guidance, smart tracking, smart early warning. Reset [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Soil & Water Conservation is the property of Bulletin of Soil & Water Conservation Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The middle reaches of the Yellow River represent an important area for the protection and development of the Yellow River Basin. Most of the area of the river basin is within the Loess Plateau, which establishes it as a fragile ecological environment. Firstly, using high-resolution data of land use in the watershed from the past 30 years, landscape ecological risk (LER) sample units are defined and an ecological risk index (ERI) model is constructed. Kriging interpolation is used to display the LER spatial patterns, and the temporal and spatial evolution of risk is examined. Secondly, the spatial evolution of land use landscape change (LULC) is analyzed, and the correlation between land use landscape and ecological risk is discussed. Finally, Based on the LER model, a risk-based minimum cumulative resistance (MCR) model is established, and a comprehensive protection and management network system for the ecological source-corridor-node system designed. The results suggest that in the past 30 years, LER has a high spatial correlation and areas with extremely high ecological risks are concentrated in northwest and southeast areas of the region, of which the northwest area accounts for the highest proportion. Risk intensity is closely related to the spatial pattern of land use landscape. ERI values of forestland, grasslands, and unused land and farmland are low, medium, and high, respectively. The trend of risk evolution is "overall improvement and partial deterioration". Man-made construction and exploitation is the most direct reason for the increase of local ecological risks. The high ecological-risk areas in the northwest are dominated by deserts which reduce excessive interference by human activities on the natural landscape. Recommendations are: high-quality farmland should be protected; forestland should be restored and rebuilt; repair and adjust the existing ecosystem to assist in landscape regeneration and reconstruction; utilize the overall planning vision of "mountain, water, forest, field, lake, grass, sand" to design a management project at the basin scale; adhere to problem-oriented and precise policy implementation. [ABSTRACT FROM AUTHOR]

In the context of climate change, extreme rainfall events have greatly increased the frequency and risk of flash floods in the Yellow River Basin. In this study, the heavy rainfall and flash flood processes were studied as a system. Taking the driving factors of the heavy rainfall causing the flash floods as the main focus, the key factors of the heavy rainfall causing typical flash flood processes were identified, and the driving mechanism by which the heavy rainfall caused flash floods was revealed. Through comparative analysis of the rainfall related to 13 floods with peak discharges of greater than 2000 m3/s since measurements began at Baijiachuan hydrological station, it was found that different rainfall factors played a major driving role in the different flood factors. The factor that had the largest impact on the peak discharge was the average rainfall intensity; the factor that had the largest impact on the flood volume was the rainfall duration; and the factor that had the largest impact on the sediment volume was the maximum 1 h rainfall. The ecological construction of soil and water conservation projects on the Loess Plateau has had obvious peak-cutting and sediment-reducing effects on the flood processes driven by medium- and low-intensity rainfall events, but for high-intensity flash floods, the flood-reducing and sediment-reducing effects of these projects have been smaller. Therefore, despite the background of continuous ecological improvement on the Loess Plateau, the possibility of floods with large sediment loads occurring in the middle reaches of the Yellow River still exists. [ABSTRACT FROM AUTHOR]

Soil quality and ecological environment have been improved in the middle reaches of the Yellow River in China. This improvement can attribute to the national project of returning farmland to forest in different years since 2000, particularly on the great slopes. Therefore, it is necessary to rapidly acquire the years of returning farmland and soil characteristics, in order to evaluate the ecological benefits of the project. Taking the middle reaches of the Yellow River as the study area, this study aims to obtain the soil’s physical and chemical properties, as well as the soil’s spectral curves for the returning cropland to forest in different years using hyperspectral imaging technology. Some spectral preprocessing were utilized, including the Savitzky-Golay Smoothing (SG), Reciprocal Logarithm (RL), the First-Order Differential (FD), Continuum Removal (CR), Principal Component Analysis (PCA), and Spectral Characteristic Parameters (SCP). The classification models were constructed for the years of returning cropland to forest using the K-means clustering (K-means), support vector machine (SVM), and Linear Discriminant Analysis (LDA). Among them, the input factors were set as The Principal Component Of Original Reflectance (R-PCA), Principal Component Of Logarithm Of The Reciprocal (RL-PCA), Principal Component Of First-Order Differential (FD-PCA), Principal Component Of Continuum Removal (CR-PCA), and SCP. The results showed that: 1) The content of Soil Organic Carbon (SOC) increased gradually, and the content of sand particles increased first and then decreased, with the increase of the years of returning cropland. The content of SOC was negatively correlated with the soil original reflectance. 2) There was a similar shape of soil original spectral curve in the different years of returning farmland, indicating the overall increasing trend. The CR preprocessing was significantly improved the absorption of the spectral curve, with the outstanding absorption characteristics at 480, 900, 1 100, 1 400, 1 900, 2 200, and 2 350 nm. 3) The highest accuracy (87.50%) was achieved in the classification model of LDA with the CR-PCA as input factor, which was the optimal classification model. The second highest accuracy (84.38%) was found in the classification model of SVM with the FD-PCA as the input factor. All the classification models with the CR-PCA as input factor shared the highest accuracy of more than 75%, with the maximum of 87.50 %, indicating that the CR-PCA was the optimal input factor to distinguish the different years of returning farmland in this case, followed by the FD-PCA. As such, the rapid distinction of the years was fully realized for the returning farmland to forest, according to the spectral characteristics and classification through the soil spectral curves. The finding can provide a strong reference for the soil properties and environmental impacts of the returning farmland to forest. [ABSTRACT FROM AUTHOR]

With years of vegetation restoration and check dam construction on the Loess Plateau, the sediment load of the middle reaches of the Yellow River have decreased sharply; however, the effects of check dam on this decrease of sediment load with such extensive vegetation restoration remains unclear. In order to further clarify the effects of check dam on sediment load reduction under vegetation restoration, we calculated vegetation coverage and check dam index based on multi-source remote sensing data, and calculated sediment reduction rate caused by human activities by Mann-Kendall statistical test and double cumulative curve, then established regression equations incorporating the check dam index and the sediment reduction rate using data from different geomorphic regions with different vegetation coverages. The results showed that sediment load in the Hekou-Longmen region and its 17 tributaries decreased significantly every year, and the change in sediment load could be divided into 3 typical periods: the base period (P1), the period mainly impacted by check dam construction (P2) and the period with comprehensive impact of check dam construction and vegetation restoration (P3). Compared with sediment load of the tributaries during P1, the sediment load decreased by 60.96% during P2 and by 91.76% during P3. Compared with the contribution of human activities to the reduction in sediment load in P2, the contribution of human activities in P3 increased significantly, while that of precipitation decreased slightly. The sediment reduction effect of check dams is greater in basins with low vegetation coverage than in basins with high vegetation coverage. There are differences in sediment reduction effect of vegetation restorations in different geomorphic regions, and the effect of vegetation restoration alone have certain upper limits. Such as, the upper limit of sediment reduction rate of vegetation restoration for rivers flowing through the sandstorm region is 47.86%. Hence, only combined the construction of check dam with vegetation restoration can it achieve more significant sediment reduction benefit and control soil erosion more effectively.

With regard to the increasingly harsh ecological environment, more and more attention is paid to the evaluation of ecological environment quality. The existing ecological environment assessment methods usually lack objectivity and are affected by certain subjectivity. In order to solve this problem, in this paper, taking the ecological environment in the middle of the Yellow River as an example, the calculation formula of ecological environment quality evaluation index information entropy is analyzed in detail based on the basic theory of information entropy, and the work flow of ecological environment quality evaluation based on entropy weight method are proposed. The vegetation coverage index and surface temperature are selected to evaluate the ecological environment in the middle reaches of the Yellow River. Through the time entropy method proposed in this paper, the long-term changes of vegetation coverage are analyzed, and the results show that the vegetation coverage has been significantly improved between 2005 and 2015. Before 2007, the vegetation coverage index did not exceed 0.5. After 2008, the vegetation coverage index showed a relatively high increase, and the ecological environment was greatly improved, reaching about 0.7 in 2015. The entropy method is used to obtain the distribution of environmental quality changes in the basin. From 2005 to 2015, the environmental quality level of the central part of the Yellow River was significantly improved and the improved area accounted for about 29% of the total area of the entire central basin. The improvement areas are mainly distributed in the northeast of the middle reaches of the Yellow River. This fully proves the accuracy and feasibility of the ecological environment quality evaluation method based on information entropy proposed in this paper. [ABSTRACT FROM AUTHOR]

From the perspective of prefecture-level cities, this paper takes the middle reaches of the Yellow River as the research object. It uses the SBM model to estimate the total factor energy efficiency (abbreviation: TFEE) in Yellow River regions from 2008 to 2016, and it uses the Tobit model to test the six external factors affecting TFEE. The results show that TFEE of different areas is different. Henan Province has the highest TFEE, followed by Shanxi, Inner Mongolia, and Shanxi Province. Except Shanxi Province, the economic development has obviously positive impact on the Yellow River regions, and the proportion of production factors has a significant negative impact on these areas. The other factors show different influence in different regions and even have no significant impact in some areas. [ABSTRACT FROM AUTHOR]

Abstract The future trend of water and sediment variation is closely related to the governance of the Yellow River. The increasingly frequent occurrence of extreme rainfall events has rendered the future water and sediment situation of the Yellow River uncertain. Understanding the characteristics of flood and sediment yield of the river basin under extreme rainfall conditions at different times is a prerequisite and foundation for accurate prediction of water and sediment situation in the Yellow River in the future period. We here used the July 26 extraordinary rainstorm event in 2017 in the Wuding River as a starting point for revealing the law of flood and sediment yields changes under extreme rainfall conditions around the year 2000. The results indicated that, during the period from 1960 to 2016, the average proportion of extreme rainfall depth in the middle Yellow River region over the total precipitation depth increased by 5.1%. Areas where extreme rainfall events frequently occur showed a trend of developing from localized regions in the Toudaoguai–Longmen reach to the majority of the middle reaches. There were obvious changes in the rainfall-flood and rainfall-sediment relations under extreme rainfall conditions. Compared with historical extreme rainfall events, the decline in flood and sediment yield in the river basin after 2000 under similar rainfall and intensity conditions was obvious. Among these results, flood decreased by 30.4–78.2%, sediment yield was decreased by 53.0–88.2% and sediment content in flood was decreased by >47.2% on average when compared with the same rainfall conditions in the previous century. Comparative watershed studies showed that, during extreme rainfall events, areas under soil and water loss management programs suffer 57.2% and 75.7% less flood runoff modulus and sediment transport modulus, respectively, than non-managed areas. This indicates that soil and water loss management is the major driving factor for changes in rainfall-flood and rainfall-sediment relations under extreme rainfall conditions. This study highlights the importance of soil and water loss management in the flood control and sediment reduction. We concluded that, with the implementation of soil and water conservation measures, the probability of large flood and sediment events will greatly decrease and the amount of sediment entering the Yellow River under extreme rainfall will further decrease in the next 30 years. Highlights • Frequency of extreme rainstorm events in the Yellow River increased significantly. • Rainstorm-sediment relations exhibited obvious changes after 2000. • Soil and water loess management plays a key role in reducing sediment. • The probability of large flood and sediment events will greatly decrease. [ABSTRACT FROM AUTHOR]

Sediment discharge from the Yellow River originates mainly from the drainage area between Hekouzhen and Longmen, i.e., the Helong area. Spatial-temporal variations of the vegetation cover in this area during the 1981–2007 period have been investigated using GIMMS and SPOT VGT NDVI data. We have also analyzed the interannual variations in vegetation cover and changes in annual runoff and sediment discharge, the consequences from precipitation change and the Grain for Green Project (GGP). The results show that vegetation cover of the Helong area has increased during the 1981–2007 period. The northwestern part the Helong area, where the flat sandy lands are covered by grass, has experienced the largest increase. The region where the vegetation cover has declined is largely found in the southern and southeastern Helong area, which is a gullied hilly area or forested. Although precipitation was relatively low during the 1999–2007 period, the vegetation cover showed a significant increase in the Helong area, due to the implementation of the GGP. During this period, the most significant improvement in the vegetation cover occurred mainly in the gullied hilly areas of the Loess Plateau, such as the drainage basins of the Kuyehe and Tuweihe rivers and the middle and lower reaches of the Wudinghe and Yanhe rivers. A comparison of the average annual maximum NDVI between the earlier (1998–2002) stage and the next five years (2003–2007) of the GGP indicates that the areas with increases of 10% and 20% in NDVI account for 72.5% and 36.4% of the total area, respectively. Interannual variation of annual runoff and sediment discharge shows a declining trend, especially since the 1980s, when the decrease became very obvious. Compared with the 1950–1969 period, the average runoff during the 1980–2007 period was reduced by 34.8×108 m3 and the sediment discharge by 6.4×108 t, accounting for 49.4% and 64.9% of that in the 1950–1969 period, respectively. There is a positive correlation between the annual maximum NDVI and annual runoff and sediment discharge. This correlation was reversed since the implementation of the GGP in 1999 and vegetation cover in the Helong area has increased, associated with the decrease in runoff and sediment discharge. Less precipitation has been an important factor driving the decrease in runoff and sediment discharge during 1999–2007. However, restoration and improvement of the vegetation cover may also have played a significant role in accelerating the decrease in annual runoff and sediment discharge by enhancing evapotranspiration and alleviating soil erosion. [ABSTRACT FROM AUTHOR]