Intra-annual sediment dynamic assessment in the Wei River Basin, China, using the AIC functional-structural connectivity index

Hydrological and sediment dynamics have changed considerably on the Chinese Loess Plateau during the last six decades due to large scale land use changes and numerous water regulation actions. Understanding the mechanism of sediment transport change and its effects is of great importance to food and environmental security. Numerical approaches are useful to map and assess spatio-temporal patterns in sediment dynamics. This study evaluates monthly and annual sediment connectivity in the Wei River Basin (134,800 km2) at the basin and sub-basin scales using the aggregated index of sediment connectivity (AIC). For the first time, this index is applied on this relatively large regional scale. The two objectives were to (1) evaluate the performance of the AIC at the regional scale, addressing substantial differences among areas, and (2) analyze how each AIC sub-factor co-determines the monthly sediment and connectivity patterns. Results show that AIC has strong or moderate positive correlation with sediment yield from 15 out of 23 stations in the Wei and Jing sub-basin. The Jing sub-basin has the highest sediment connectivity due to degraded vegetation, while the Beiluo sub-basin has the lowest sediment connectivity on average due to better ecological restoration. Within the year, sediment connectivity is highest in April and lowest in January, due to the rainfall regime and intra-annual land cover variations. Among the AIC factors, the rainfall factor has the highest effect on sediment connectivity, implying that functional connectivity (graded by rainfall and soil cover) determines sediment dynamics more than structural connectivity (mainly determined by topography and soil permeability). This study provides one of the first large-scale estimates of spatial and temporal sediment connectivity from hillslopes to river stream and including large reservoirs, which can be further employed to implement regional ecological construction works and environmental catchment management.info:eu-repo/semantics/publishedVersio

China’s Conversion of Cropland to Forest Program: A systematic review of the socioeconomic and environmental effects

Background Farming on sloping lands has historically led to forest loss and degradation in China which, coupled with timber extraction activities, was deemed responsible for catastrophic flooding events in the late 1990s. These events led to the introduction of forest policies targeting ecological conservation and rural development in China, a process epitomized by the launch of the Conversion of Cropland to Forest Program (CCFP) in 1999. Methods/design This systematic review responds to the question: What environmental and socioeconomic effects has the Conversion of Cropland to Forest Program had on land resources and human populations during its first 15 years? Following the published protocol, we searched for English language studies published between 1999 and 2014, and screened them for relevance and eligibility in two stages (titles and abstracts followed by full texts), after which they were further assessed for potential sources of bias (study quality assessment) before data extraction and analyses. Forty three studies were identified as meeting our inclusion and quality criteria following screening of 879 search results, indicating an overall lack of high quality studies with primary data on the impacts of CCFP. Eighty per cent of county-level case studies were conducted in only four provinces, and 13 of the 25 provinces where the CCFP is implemented are not represented by these county-level cases in the review. The review also includes, however, four national level studies covering 20 provinces and seven regional level studies, each covering several provinces. The majority of studies were published after 2009 and evaluated impacts within the first five years of CCFP implementation, such that the long term impacts of the program remain open for further investigation. Results The skewed temporal and geographic distribution of studies limits the generalizability of the results, though the evidence base confirms a substantial increase in forest cover and associated carbon stocks linked to reallocation of sloping agricultural land to forest. To some degree, soil erosion has been controlled and flood risk reduced at local scales. Meanwhile household incomes have increased and rural employment has readjusted towards off-farm sectors. However, studies also indicate instances of diminished food security and increasing social inequality. Finally, several studies indicate suboptimal regional or localized tradeoffs among specific ecosystem services, including carbon sequestration vs. water discharge rates, flood control vs. riparian soil replacement, and forest productivity vs. biodiversity. Conclusions Additional research on long-term environmental impacts and program effects in under-studied regions, particularly southern and western provinces, is necessary. In terms of recommendations for future research on the CCFP, there is a significant need to examine confounding factors, ideally through the selection of matching control groups to CCFP participants, and to ensure sampling methodologies are more representative of selected study sites and the overall targeted area. There remain many opportunities to assess specific socioecological effects, upon which to base future policy decisions and more broadly inform ecological restoration and eco-compensation in both theory and practice.Peer reviewe

Climate Change and Environmental Sustainability-Volume 4

Anthropogenic activities are significant drivers of climate change and environmental degradation. Such activities are particularly influential in the context of the land system that is an important medium connecting earth surface, atmospheric dynamics, ecological systems, and human activities. Assessment of land use land cover changes and associated environmental, economic, and social consequences is essential to provide references for enhancing climate resilience and improving environmental sustainability. On the one hand, this book touches on various environmental topics, including soil erosion, crop yield, bioclimatic variation, carbon emission, natural vegetation dynamics, ecosystem and biodiversity degradation, and habitat quality caused by both climate change and earth surface modifications. On the other hand, it explores a series of socioeconomic facts, such as education equity, population migration, economic growth, sustainable development, and urban structure transformation, along with urbanization. The results of this book are of significance in terms of revealing the impact of land use land cover changes and generating policy recommendations for land management. More broadly, this book is important for understanding the interrelationships among life on land, good health and wellbeing, quality education, climate actions, economic growth, sustainable cities and communities, and responsible consumption and production according to the United Nations Sustainable Development Goals. We expect the book to benefit decision makers, practitioners, and researchers in different fields, such as climate governance, crop science and agricultural engineering, forest ecosystem, land management, urban planning and design, urban governance, and institutional operation.Prof. Bao-Jie He acknowledges the Project NO. 2021CDJQY-004 supported by the Fundamental Research Funds for the Central Universities and the Project NO. 2022ZA01 supported by the State Key Laboratory of Subtropical Building Science, South China University of Technology, China. We appreciate the assistance of Mr. Lifeng Xiong, Mr. Wei Wang, Ms. Xueke Chen, and Ms. Anxian Chen at School of Architecture and Urban Planning, Chongqing University, China

Spatiotemporal variations and its driving factors of soil conservation services in the Three Gorges Reservoir area in China

Soil conservation services play a vital role in regulating ecosystem services to prevent soil erosion and ensure regional ecological security. Therefore, effective evaluation and quantification of soil conservation services in the Three Gorges Reservoir Area (TGRA) are conducive to sustainable management under future global change. In this study, based on a basic database, including land use/cover data, soil data, topographic data, meteorological data, and NDVI (Normalized Difference Vegetation Index) data as the basic databases, to evaluate the temporal and spatial changes of soil conservation services in the TGRA from 1990 to 2015 at a regional-scale level using the general soil loss equation. The results showed that forest ecosystems (including coniferous and broad-leaved mixed forests, coniferous forests, shrub forests, and broad-leaved forests) made a greater contribution (69%) to regulating soil conservation in TGRA, followed by farmland ecosystems (29%). In total TGRA, large spatial variation in soil conservation, such as the highest appeared in the northern hinterland, whereas the lowest was mostly shown in the northwest with relatively frequent human activities and developed industry and agriculture. In general, soil conservation in the TGRA ecosystem gradually increased from 1990 to 2015, with a total increase of 6%. In this period, with the effective implementation of ecological projects, such as the conversion of farmland to forest and natural forest protection, the distributed proportion of forest land area in total TGRA showed a significant increase. In the meantime, the increase of vegetation coverage also helps the restoration of ecosystem structure and function and the improvement of soil conservation services. Our findings will aid our knowledge regarding the ecosystem services of the TGRA and provide implications for future sustainable land management and ecological protection

New Approach for Evaluation of a Watershed Ecosystem Service for Avoiding Reservoir Sedimentation and Its Economic Value: A Case Study from Ertan Reservoir in Yalong River, China

A model was established to simulate an ecosystem service of avoiding reservoir sedimentation and its economic value based on the process of sediment delivery in a watershed. The model included fabricating the watershed of the study reservoir. The sediment retention coefficient of different land cover types were used to simulate the spatial patterns of the annual quantity of the sediment that were prevented from entering the reservoir by the vegetation in each cell followed the flow path in watershed. The economic value of the ecosystem service in this model was determined by the marginal cost of reservoir desilting. This study took the Ertan reservoir as an example. The results showed that most eroded soil was intercepted by different types of ecosystems in the process of sediment delivery in a watershed. The region with a higher quantity of sediment retention was around the reservoir. The absolute quantity of average sediment retention in forestland was lower, so the sediment retention ability of forestland failed to be brought into fullest play in watershed

Soil-Water Conservation, Erosion, and Landslide

The predicted climate change is likely to cause extreme storm events and, subsequently, catastrophic disasters, including soil erosion, debris and landslide formation, loss of life, etc. In the decade from 1976, natural disasters affected less than a billion lives. These numbers have surged in the last decade alone. It is said that natural disasters have affected over 3 billion lives, killed on average 750,000 people, and cost more than 600 billion US dollars. Of these numbers, a greater proportion are due to sediment-related disasters, and these numbers are an indication of the amount of work still to be done in the field of soil erosion, conservation, and landslides. Scientists, engineers, and planners are all under immense pressure to develop and improve existing scientific tools to model erosion and landslides and, in the process, better conserve the soil. Therefore, the purpose of this Special Issue is to improve our knowledge on the processes and mechanics of soil erosion and landslides. In turn, these will be crucial in developing the right tools and models for soil and water conservation, disaster mitigation, and early warning systems

The Effect of Hydrology on Soil Erosion

This Special Issue includes manuscripts about soil erosion and degradation processes and the accelerated rates due to hydrological processes and climate change. The new research included in this issue focuses on measurements, modeling, and experiments in field or laboratory conditions developed at different scales (pedon, hillslope, and catchment). This Special Issue received investigations from different parts of the world such as Ethiopia, Morocco, China, Iran, Italy, Portugal, Greece, and Spain, among others. We are happy to see that all papers presented findings characterized as unconventional, provocative, innovative, and methodologically new. We hope that the readers of the journal Water can enjoy and learn about hydrology and soil erosion using the published material, and share the results with the scientific community, policymakers, and stakeholders to continue this amazing adventure, facing plenty of issues and challenges

Impacts of ecological restoration programs on water-related ecosystem services: A case study in northern Shaanxi, China

Pour restaurer les fonctions écosystémiques altérées, la Chine a instauré plusieurs programmes de restauration écologique (PRE) à grande échelle. Ces programmes ont généré des changements significatifs sur l’occupation du sol et sur les services écosystémiques (SE) définis comme étant les bénéfices procurés aux humains par les écosystèmes. Les écosystèmes sont critiques pour le bien-être humain, mais notre connaissance actuelle de la fourniture des SE dans le paysage contient des lacunes qui limitent notre capacité à mieux comprendre l’impact des PRE sur ce bien-être humain. Plus particulièrement, la compréhension des impacts des changements d’occupation du sol sur la fourniture des SE en régions semi-arides et arides en Chine reste floue. Dans la présente thèse, le but général de recherche est l’évaluation à long terme de l’impact des PRE sur les SE liés à l’eau, particulièrement l’érosion du sol et l’apport en eau dans une région semi-aride chinoise, le Shaanxi septentrional. Afin d’atteindre cet objectif, les étapes du projet sont: l’analyse des changements d’occupation du sol avant et après l’implantation des PRE, l’estimation de l’érosion du sol et de l’apport en eau à différentes échelles spatiales et temporelles, l’analyse des relations entre le changement d’occupation du sol et les SE liés à l’eau et des relations entre l’érosion du sol et l’apport en eau et finalement l’analyse des impacts potentiels futurs des PRE sur les SE liés à l’eau à l’aide de différents scénarios. Les résultats ont montré que l’implantation des PRE dans le Shaanxi du nord avait provoqué une augmentation des prairies et des terres boisées et une diminution des terres cultivées. Dans le même temps, la principale caractéristique du changement de SE lié à l’eau au cours de la période d’implantation des ERP était la diminution de l’érosion du sol et de l’apport en eau dans le site d’étude. Cependant, en se basant sur une analyse à l’échelle des sous-bassins versants, il a été constaté que les zones boisées et les prairies n’avait pas augmenté dans tous les sous-bassins au cours de la période d’implantation des ERP. De plus, l'érosion des sols dans trois sous-bassins versants a même augmenté après la mise en œuvre des PRE, alors que l'apport en eau dans tous les sous-bassins versants a diminué durant la même période. Les relations entre les types d’occupation du sol et les SE liés à l'eau ont varié d'un sous-bassin à l'autre. En ce qui concerne l'érosion du sol, 95% de la zone d'étude a montré une relation positive, indiquant que l'augmentation de la superficie des terres cultivées est liée à une augmentation de l'érosion du sol. En d'autres termes, la diminution des superficies cultivées peut aider à réduire le risque d'érosion des sols. Cependant, les relations négatives observées entre les terres boisées et l'érosion du sol et entre les prairies et l'érosion du sol n’ont été observées que dans la plupart des sous-bassins nord, ce qui suggère que l'augmentation des zones boisées et des prairies dans la plupart des sous-bassins versants du nord peut aider à réduire le risque d'érosion du sol. Ainsi, la mise en œuvre des ERP dans les régions du nord du site d'étude a eu des impacts positifs sur l'érosion des sols. En ce qui concerne l'apport en eau, 65% de la zone d'étude (21 sous-bassins versants) présentaient une relation négative entre les terres boisées et l'apport en eau, tandis que 40% de la zone d'étude (neuf sous-bassins versants) a montré une relation négative entre les prairies et l’apport en eau durant la période d’activité des PRE. Ces résultats indiquent que l'augmentation des terres boisées et des prairies peut diminuer l'apport en eau dans la plupart des sous-bassins versants du nord du Shaanxi. Enfin, il a également été constaté que des compromis existaient entre l’érosion du sol et l’apport en eau, ce qui signifie qu’une amélioration du service de l’érosion est obtenue au prix d’une diminution de l’approvisionnement en eau dans le nord du Shaanxi. Sur la base de notre analyse de scénarios, les PRE sont susceptibles de continuer à être d’importants et d’influents facteurs sur l'érosion des sols et l'approvisionnement en eau dans le cadre des scénarios de protection et de statu quo. Par rapport à l'année de référence (2015), l'érosion du sol a montré une tendance à la baisse dans les scénarios de protection et de statu quo, mais les résultats de la simulation ont montré des différences relativement faibles dans les deux scénarios. De plus, l’apport en eau parmi trente sous-bassins diminuerait de 28% (scénario sans changement d’occupation du sol), de 29% (scénario de statu quo) et de 37% (scénario de protection). Ces résultats indiquent également que le climat (par exemple les précipitations et l'évapotranspiration), les PRE et leurs interactions exerceront probablement des pressions considérables sur l'approvisionnement en eau d'ici 2050. Ainsi, les pratiques de restauration écologique actuelles pourraient soutenir la conservation des sols et de l'eau dans le nord du Shaanxi.Abstract: To repair the damaged ecosystem functions, China has implemented several largescale ecological restoration programs (ERPs). These programs have exerted significant changes on land use and land cover (LULC) and ecosystem services (ES), benefits that people obtain from ecosystems. Ecosystems are critical to human well-being, but our current knowledge of the provision of ES across landscapes contains gaps that limit our ability to better understand the impact of ERPs on human well-being. In particular, how the changes in LULC affect multiple ES provision in semi-arid and arid regions in China remains unclear. In this thesis, the overall research goal is to evaluate the impacts of ERPs on waterrelated ES, namely soil erosion and water yield, in a semiarid region (northern Shaanxi, China), in the long-term period. To attain this goal, the specific steps are: analyse LULC changes before and after implementation of ERPs, estimate soil erosion and water yield at different temporal and spatial scales, assess the relationship between LULC change and water-related ES and the relationship between soil erosion and water yield, and finally, analyse potential impacts of ERPs on water-related ES in the future through different conservation scenarios. Results showed that the implementation of ERPs in northern Shaanxi caused grasslands and woodlands increase as well as croplands decrease. At the same time, the major characteristic of water-related ES change during the ERPs period was that both soil erosion and water yield decreased in the study site. However, based on sub-watershed scale analysis, it was found that woodland and grassland in each sub-watershed did not always increase during the ERPs period. Moreover, soil erosion in three sub-watersheds actually increased after implementation of the ERPs, while water yield in all sub-watersheds decreased during the ERPs period. Relationships between LULC types and water-related ES varied from one subwatershed to another. As for soil erosion, 95% of the study area showed a positive relationship, indicating that higher cropland increase is linked to higher soil erosion increase. In other words, decreasing cropland areas can help reduce the risk of soil erosion. However, the negative relationships between woodlands and soil erosion and between grasslands and soil erosion only existed in most north sub-watersheds, indicating that higher woodland/grassland increase is related to lower soil erosion increase. This result suggested that increased woodlands and grasslands in most north sub-watersheds can help reduce the risk of soil erosion. Thus, implementation of the ERPs in north regions in the study site has positive impacts on soil erosion. As for water yield, 65% of the study area (twenty-one sub-watersheds) showed a negative relationship between woodlands and water yield, while 40% of the study area (nine sub-watersheds) showed a negative relationship between grasslands and water yield after implementation of ERPs. These results indicated that increased of woodland and grassland can decrease water yield in most sub-watersheds in northern Shaanxi. Lastly, it was also found that trade-offs existed between soil erosion and water yield, which means that an improvement in erosion service is achieved at the expense of a decrease in the provision of water in northern Shaanxi. Based on our scenario analysis, the ERPs are likely to be continued as important and influential on soil erosion and water provision under protection and business-as-usual (BAU) scenarios. Compared with the baseline year (2015), soil erosion showed a decrease tendency under protection and BAU scenarios, but simulation results showed relatively small differences under both scenarios. Moreover, water yield among thirty sub-watersheds would decrease by 28% (No LULC change scenario), 29% (BAU scenario), and 37% (protection scenario). These results also indicate that climate (i.e. precipitation and evapotranspiration), the ERPs and their interactions are likely to place substantial pressures on the provision of water by 2050. Thus, current ecological restoration practices might support soil and water conservation in the future in northern Shaanxi

The study of agricultural non-point source pollution control policy system

As the agricultural non-point source pollution(ANPSP) has become the most significant threat for water environmental deterioration and lake eutrophication in China, more and more scientists and technologists are focusing on the control countermeasure and pollution mechanism of agricultural non-point source pollution. The unreasonable rural production structure and limited scientific management measures are the main reasons for acute ANSPS problems in China. At present, the problem for pollution control is a lack of specific regulations, which affects the government\u27s management efficiency. According to these characteristics and problems, this paper puts forward some corresponding policies. The status of the agricultural non-point source pollution of China is analyzed, and ANSPS prevention and control model is provided based on governance policy, environmental legislation, technical system and subsidy policy. At last, the case analysis of Qiandao Lake is given, and an economic policy is adopted based on its situation