Chengdu Plain Research Articles

Spatial and temporal variations of drought in Sichuan Province from 2001 to 2020 based on modified temperature vegetation dryness index (TVDI)

Investigating the drought response to evapotranspiration and climate change was key to understanding the dynamics of drought changes and the mechanism of drought changes in the future. In this study, a modified Temperature Vegetation Drought Index was constructed based on the correction of elevation and incorporating air temperature and also based on climate indices recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI) the effects of evaporation and vegetation cover on the drought in Sichuan Province were investigated. The results showed that: the degree of drought in the northwestern Sichuan Plateau (0.57 < TVDI < 0.86) was weaker than in other regions (the Chengdu Plain, the Eastern Sichuan Basin Plain, and southwestern Sichuan's mountainous region) with TVDI ≤ 0.86. Agricultural land and construction land had a relatively high degree of drought (0.76 < TVDI < 0.86), the decreasing trend was insignificant in the whole province. The drought degree in spring was the least, and the main trend was insignificant; 0–0.01/a in summer. The drought in autumn and winter was more severe, and most areas of the province were extremely dry, showing an increasing trend. The minimum and maximum value of ET was concentrated in the northwestern Sichuan Plateau (ET < 130 mm) and the Sichuan Basin (ET ≤ 170 mm), respectively. ET of water bodies (ET ≥ 170 mm) was the highest, and lowest in construction land (90 < ET < 130 mm). The increase rate of ET was highest in spring and lowest in winter. TVDI was negatively correlated with annual precipitation in the northwestern Sichuan Plateau, Jinsha River Valley, and eastern Chengdu Plain, positively correlated with annual temperature and positively correlated with the yearly minimum value of daily minimum temperature (TNn), the yearly minimum value of daily maximum temperature (TXn), and the yearly maximum value of daily minimum temperature (TNx), and negatively correlated with the yearly maximum value of daily maximum temperature (TXx) and the yearly maximum consecutive five-day precipitation (PX5). The results are useful for the understanding of drought and policy making of climate change.

Significance of fluvial landform evolution and river reorganization in settlement development over the past 50 ka: A case study of Baodun site on Chengdu Plain, SW China

The Baodun archaeological site, which is representative of Baodun Culture (4.5–3.6 cal. ka BP), is a well-known walled site covering large areas of the Chengdu Plain (CDP), which is located in the upper reaches of the Yangtze River. The CDP is a low-lying sedimentary basin that is one of the cradles of Chinese civilization and was formed by many rivers originating from the northeastern part of the Qinghai–Tibetan Plateau. Geological and hydrological characteristics have strongly influenced the development of ancient cultures on the CDP. However, their relationship has not been validated. Based on field investigations, ground surveys, microgeomorphological discrimination, grain-size measurements, tree species identification, and the analysis of fluvial deposits, including age dating, height measurement, and observations of gravel layers, we investigated the effects of geomorphology and river channel migration on the evolution of the Baodun site. The results showed that three grades of terraces developed at the Baodun site region during the past ~50 ka BP, which had important impacts on the regional evolution of geomorphology and river systems. The chronology constrains the ages of terraces T1, T2, and T3 to ~7, ~22, and ~48 ka, respectively; T2 and T3 were closely related to tectonic activity, whereas T1 was related to climate variation. Similar to the modern river system, ancient waterflow primarily originated from the northwest; however, it mixed with water from other directions in the past. We attribute the construction of the Baodun site to the persistently outcropped terraces and the attraction of more stable rivers, which provided space and resources for the Baodun people. The evolution of the river system influenced the safety of the Baodun site, and flooding was the main factor leading to its decline and abandonment. The stability of the terrace and sedimentary environments and the decreased precipitation were important factors influencing the large-scale habitation of archaeological sites on the CDP during the middle and late Holocene.

Development Trend Prediction of Chengdu Plain Economic Zone Based on Multiple Linear Regression Grey Correlation Degree

Urban agglomeration is the mainstream trend of urban development in the world. It is also the main form of new urbanization in China and an important platform to participate in international competition and cooperation. The pattern of industrial division of labor has basically taken shape in Chengdu Plain Economic Zone, and the industrial cooperation system has been gradually established. However, the phenomenon of industrial isomorphism is still prominent. In the process of promoting coordinated industrial development, there are still some problems such as disunity of understanding, imperfect mechanism, and imperfect environment. The regional economic potential is influenced by too many entities and the dynamic changes of economic structure, and the change ratio is highly nonlinear. In this paper, a MLR-GCD (Multiple Linear Regression Grey Correlation Degree) prediction model for the development trend of Chengdu Plain Economic Zone is proposed. In the decision-making process, MLR (multiple linear regression) method is introduced to construct the GCD (Grey Correlation Degree) of training economic-related data set, and then the GCD is pruned to transform it into standard decision-making data. The experimental results show that compared with other prediction models, the improved model has higher accuracy of regional economic prediction, can quickly and accurately predict the development potential trend of Chengdu Plain Economic Zone, and has important application value.

Detection of dominant factors and interactions of spatial heterogeneity of soil heavy metals in northern Chengdu Plain, western China

Detection of dominant factors and interactions of spatial heterogeneity of soil heavy metals in northern Chengdu Plain, western China

Natural- and Human-Induced Influences on Terrestrial Water Storage Change in Sichuan, Southwest China from 2003 to 2020

A quantitative understanding of changes in water resources is crucial for local governments to enable timely decision-making to maintain water security. Here, we quantified natural-and human-induced influences on the terrestrial water storage change (TWSC) in Sichuan, Southwest China, with intensive water consumption and climate variability, based on the data from the Gravity Recovery and Climate Experiment (GRACE) and its Follow-on (GRACE-FO) during 2003–2020. We combined the TWSC estimates derived from six GRACE/GRACE-FO solutions based on the uncertainties of each solution estimated from the generalized three-cornered hat method. Metrics of correlation coefficient and contribution rate (CR) were used to evaluate the influence of precipitation, evapotranspiration, runoff, reservoir storage, and total water consumption on TWSC in the entire region and its five economic regions. The results showed that a significant improvement in the fused TWSC was found compared to those derived from a single model. The increase in regional water storage with a rate of 3.83 ± 0.54 mm/a was more influenced by natural factors (CR was 53.17%) compared to human influence (CR was 46.83%). Among the factors, the contribution of reservoir storage was the largest (CR was 42.32%) due to the rapid increase in hydropower stations, followed by precipitation (CR was 35.16%), evapotranspiration (CR was 15.86%), total water consumption (CR was 4.51%), and runoff (CR was 2.15%). Among the five economic regions, natural influence on Chengdu Plain was the highest (CR was 48.21%), while human influence in Northwest Sichuan was the largest (CR was 61.37%). The highest CR of reservoir storage to TWSC was in Northwest Sichuan (61.11%), while the highest CRs of precipitation (35.16%) and evapotranspiration (15.86%) were both in PanXi region. The results suggest that TWSC in Sichuan is affected by natural factors and intense human activities, in particular, the effect of reservoir storage on TWSC is very significant. Our study results can provide beneficial help for the management and assessment of regional water resources.

Analysis on the spatial differentiation characteristics of poverty risk caused by disaster under the stress of geological disasters: a case study of Sichuan Province.

Research on the poverty risk caused by geological disasters in disaster-prone areas is a useful exploration to coordinate social economic development with disaster prevention and reduction, and is of great significance to the regional sustainable development. Based on statistical data and spatial data, this paper takes Sichuan Province as the typical research area. Remote sensing and geographic information technology are used to study the poverty risk caused by disasters based on the quantitative evaluation of geological disasters risk and regional development level. The spatial differentiation characteristics of poverty risk caused by disasters are explored on the 1km × 1km grid scale. The results indicate that (1) the overall risk of geological disasters in Sichuan Province is relatively high, with high and relatively high risk areas accounting for more than 40% and low and relatively low risk areas accounting for less than 30%. The risks in Mountain and Ravine Areas are significantly higher than other areas. (2) The regional development level in Sichuan Province is relatively high, but with significant spatial differences. The development level of high-altitude areas and remote mountainous areas is quite different from that of the Chengdu Plain in the middle Sichuan Province. The uneven development in the east, middle, and west is a prominent problem. (3) The poverty risk caused by disasters is high, and the spatial pattern presents a characteristic of "high in the west and low in the east" with high positive spatial correlation. High-High Cluster Areas are mainly distributed in western and southwestern Sichuan. Low-Low Outlier Areas are mainly distributed in Chengdu Plain and Hilly Areas of Sichuan Basin. High-Low Outlier and Low-High Outlier Areas occupy a relatively small percentage with scattered distribution. This paper provides some theoretical support for policy formulation and management of coordinated development of regional socioeconomic and ecological environment.

Regional landscape transformation and sustainability of the rural homegarden agroforestry system in the Chengdu Plain, China

Traditional rural homegarden agroforestry system in the Chengdu Plain of China, called “Linpan” in Chinese, integrates the ecological functions of the landscape with human production activities. Studying the driving mechanisms of rural landscape changes in the Chengdu Plain is of great significance from stakeholders’ perspective. Taking the Pidu Linpan Farming System (PLFS) in the suburban area of Chengdu (designated as one of China-Nationally Important Agricultural Heritage Systems in 2020) as a case, this study combined remote sensing image analysis, oral history interviews, and focus group interviews to elucidate the driving forces of landscape changes in the PLFS. The results show that tourism development, traffic accessibility, economic demand, and agricultural heritage protection measure are the main driving forces promoting the stability and maintenance of the traditional homegardens. In contrast, population ageing, land circulation, centralized residence, climate change, and living and recreational need are the forces leading to adverse changes in the traditional homegardens. In addition, these driving forces have led to the gradual abandonment of traditional agricultural activities and critical issues related to rural landscape planning and management. The current research indicates that infrastructure construction and increased traditional agricultural income are considered as the best practices of local stakeholders, promoting the development of the protected homegardens of heritage sites and tourist destinations. Finally, we put forward some suggestions to improve and maintain the traditional rural landscape: (1) establishing a benefit-sharing mechanism; (2) establishing a training system with traditional technology and culture; (3) strengthening infrastructure construction; (4) promoting the development of the agricultural industry; (5) improving the cultural quality of farmers; and (6) establishing a management system with legal effects. This research can provide a basis for the formulation of rural landscape planning and the orderly and healthy development of agricultural heritage in Chengdu Plain.

Geometry of the Quaternary strata along the middle segment of the Longmen Shan and its formation mechanism: Insights from AMT，ERT and borehole data

Syntectonic sediments record the growth process of active fold and fault belts. The Quaternary in the Chengdu plain are the syntectonic sediments formed during the structure deformation of the Longmen Shan in Late Cenozoic, which is of great significance for understanding the formation and evolution of the Longmen Shan. However, the geometry and formation of the Quaternary in the Chengdu plain are still unsettled. This paper determines the Quaternary thickness in the Chengdu plain with audio magnetotellurics (AMT), electrical resistivity tomography (ERT) and borehole, and discusses the formation of Quaternary in the Chengdu plain in combination with previous deep and surface data. It also predicts the Quaternary geometry in Chengdu plain by AMT, and concludes that the thickness in Huayuan may be larger than that in Zhuwapu (541 m). The borehole reveals that the Quaternary thickness in the Huayuan is upto 571.3 m, which is the thickest Quaternary so far. With the Longmen Shan piedmont wedging into the Sichuan basin, and under the intense erosion of Minjiang river, structure wedges of different scales are formed and result in salient and recess, which corresponds to the geometry of the Quaternary in the Chengdu plain. Therefore, the coupling between deep structures and surface processes controls the formation of the Quaternary in the Chengdu plain.

Farmers’ Strategies to Climate Change and Urbanization: Potential of Ecosystem-Based Adaptation in Rural Chengdu, Southwest China

Ecosystem-based adaptation (EbA) is emerging as a cost-effective approach for helping people adapt to climate and non-climate changes. Nowadays, climate change and urbanization have affected agricultural systems, but it is not clear how rural communities have responded or adapted to those changes. Here, we chose two typical villages in the Chengdu Plain, southwest China, through sociological surveys on 90 local farmers with a semi-structured questionnaire, participatory observation, geospatial analysis of land use and land cover, and a literature review, to explore the local people’s perception of changes or disturbances and their adaptation strategies from the perspective of EbA. The results showed that climate change and urbanization had impacted agricultural systems dramatically in the last 40 years. In two case-study sites, climate change and urbanization were perceived by most local farmers as the main drivers impacting on agricultural production, but various resource-use models containing abundant traditional knowledge or practices as well as modern tools, such as information communication technology (ICT), were applied to adapt to these changes. Moreover, culture service through the adaptive decoration of rural landscapes is becoming a new perspective for implementing an EbA strategy. Finally, our findings highlighted the potential value of an EbA strategy for sustaining urban-rural integrated development and enhancing the resilience of agricultural systems.

Total factor productivity of land urbanization under carbon emission constraints: a case study of Chengyu urban agglomeration in China

In consideration of energy and environmental inefficiency brought about by urban construction, sustainable urbanization has become a hot issue in recent years. In the process of land urbanization, the source of economic growth can be attributed to technical progress and efficiency improvement. To explore the driving factors of land urbanization efficiency and its dynamic changes, the total factor productivity (TFP) and its components of land urbanization was introduced. The spatial-temporal variations of land urbanization of Chengyu urban agglomeration in Western China were estimated by using the Malmquist-Luenberger (ML) productivity index with undesirable output in this study. Results demonstrate that: (1) the average TFP of land urbanization (LUTFP) of Chengyu urban agglomeration in China over time with carbon emissions (1.029) is 1.2 percent lower than that without carbon emissions (1.041). Furthermore, the LUTFP with CO2 emissions is lower than the LUTFP without CO2, demonstrating that land urbanization generates social and economic benefits at the cost of resource consumption. (2) LUTFP of Chengyu urban agglomeration under carbon emission constraints presents a generally rising trend in the past ten years and technical progress is the major source of such growth. Efficiency has become a major barrier against the improvement of productivity. (3) LUTFP indexes in Chongqing City and Chengdu plain economic region are generally higher than those of the south and northeast Sichuan economic zones. However, LUTFP of different cities tends to be in equilibrium gradually.

Wulingshen, the massive Xylaria sclerotia used as traditional Chinese medicine, is produced by multiple species

ABSTRACT Wulingshen, massive Xylaria sclerotia, was originally reported from Chengdu Plain in western Sichuan of China for medicinal application. Xylaria nigripes is commonly connected to these massive sclerotia produced within abandoned underground macrotermitine termite nests. We sequenced 54 Wulingshen samples procured from traditional Chinese medicine markets in Chengdu Plain and connected them to six different Xylaria species: X. nigripes, X. subescharoidea, two species newly described herein—X. neonigripes and X. rogersionigripes, and two species that are known only as sclerotia thus far. Only teleomorphs of X. subescharoidea and X. rogersionigripes have been collected in Chengdu Plain thus far. In Taiwan, teleomorphs of four of the six species, except for the two only known in sclerotial form, have been collected, and their cultures were obtained; we thus designate the holotypes of X. neonigripes and X. rogersionigripes on the basis of Taiwan specimens. During the collecting activities carried out in Chengdu Plain, a Xylaria species, which is newly described as X. mianyangensis herein, was also collected from termite nests but lacks a known connection to Wulingshen.

Exploring the Distribution of Forest Recreation Resources in Sichuan Province Based on GIS Spatial Statistics

Sichuan Province has excellent basic conditions for forest recreation. Sichuan Province is divided into six regions, namely, Chengdu Plain, Qinba Mountain, Panxi, Southeast Sichuan, West Sichuan and East Sichuan. According to the existing data and the needs of forest recreation evaluation in Sichuan Province, the aggregation index, superiority index and scale index are selected to calculate the regional development potential and are used as evaluation indices for evaluation. GIS and spatial statistics are used to analyze the distribution and pattern of recreation resources in Sichuan Province, and to provide reference and support for the future planning direction and strategic layout of forest recreation in Sichuan Province.

Role of Meteorology-Driven Regional Transport on O3 Pollution Over the Chengdu Plain, Southwestern China

Role of Meteorology-Driven Regional Transport on O3 Pollution Over the Chengdu Plain, Southwestern China

Study of the Characteristics of Pollutants in Rural Domestic Sewage and the Optimal Sewage Treatment Process: A Chengdu Plain Case Study

Study of the Characteristics of Pollutants in Rural Domestic Sewage and the Optimal Sewage Treatment Process: A Chengdu Plain Case Study

Characteristic Analysis of Dual-Polarization Weather Radar Echoes of Convective Precipitation and Snowfall in the Mount Everest Region

This paper introduces the X-band weather radar dual-polarization parameters of isolated convective cell precipitation and meso/microscale snowfall on Mount Everest and presents the first precipitation observations based on dual-polarization weather radar in this area. Compared with the Chengdu Plain, Mount Everest experienced convective precipitation on smaller horizontal and vertical scales with a narrower Zdr probability density spectrum (uniformly distributed around approximately 0). The Zh profile on Mount Everest displayed two peaks, unlike that over the plains, and the precipitation at the strong convective core was denser. Furthermore, during winter snowfall on the northern slope of Mount Everest, when the boundary layer exhibited sufficient water vapor and dynamic uplift, due to the low boundary layer temperature (&lt;0 °C), water vapor produced stratiform clouds in the middle and lower layers (approximately 1.5 km above ground level (AGL)). Water vapor condensation at 1.5–2.5 km AGL led to latent heat release, which increased the temperature of regional stratiform clouds with increasing height. Consequently, the temperature at the stratiform cloud top height (2.5 km AGL) unexpectedly exceeded 0 °C. Additionally, the −20 °C isotherm was at approximately 4 km AGL, indicating that the middle- and upper-layer atmospheric temperatures remained low. Therefore, thermal instability occurred between the stratiform cloud top height and the middle/upper atmosphere, forming convective motion. These findings confirm the occurrence of elevated winter snowfall convection above Mount Everest and may have certain reference value for retrieving raindrop size distributions, quantitatively estimating precipitation, and parameterizing cloud microphysical processes in numerical prediction models for the Qinghai-Tibetan Plateau.

Neolithic Rice Cultivation and Consequent Landscape Changes at the Baodun Site, Southwestern China

Identifying when agricultural expansion has occurred and how it altered the landscape is critical for understanding human social survival strategies as well as current ecological diversity. In the present study, phytolith records of three profiles from the Baodun site area were dated to the period from 7,500 to 2,500 aBP by optically stimulated luminescence and 14C dating, providing the first evidence that the Asian cultivated rice (Oryza sativa) progenitor was distributed in the Chengdu Plain as early as 7,500 aBP. The percentage of rice bulliform with ≥9 scales and the concentration of rice phytoliths sharply increased by approximately 4,200 aBP, suggesting that rice cultivation occupied a dominant position in survival strategy no later than approximately 4,200 aBP, which might be driven by climate deterioration in eastern China. The results further showed that the proportion of Bambusoideae phytoliths increased synchronously with the increase in the proportion of rice phytoliths, suggesting that the vegetation structure near the site was changed intentionally as a consequence of increasing rice agricultural activity since 4,200 aBP. The present study contributes to a deeper understanding of the distribution of wild rice and rice farming throughout the Baodun culture in the Chengdu Plain, and it also provides a glimpse of how humans intentionally changed the vegetation landscape on a local scale.

A GIS-based analysis of intrinsic vulnerability, pollution load, and function value for the assessment of groundwater pollution and health risk

Groundwater pollution risk assessment is an effective tool for the control and prevention of groundwater pollution. However, the risk is generally difficult to interpret because it is affected by both natural and anthropic factors such as topography, aquifer characteristics, land-use changes, and mining process. In this study, a GIS-based analysis of aquifer vulnerability (V), groundwater pollution load (L), and groundwater function value (F) were combined to comprehensively evaluate the groundwater pollution risk in a typical mixed land use area of Chengdu Plain, in China. Groundwater pollution risk assessment was then validated by a groundwater quality evaluation using the comprehensive water quality index method. A health risk assessment was conducted to evaluate the susceptible population exposed to the groundwater pollution. The results showed that the estimated ‘high’ and ‘very high’ pollution risk areas together accounted for 24.85% of the study area, mainly located in the southeast and southwest of the plain area with highly permeable aquifer, abundant amounts of groundwater storage, a shallow water table, and near pollution sources. In addition, our results revealed that 14% of groundwater in the study area posed an unacceptable non-carcinogenic health risk to children. The risk assessment of groundwater pollution and human health in the study area can provide effective support for strengthening groundwater management and pollution control.

Analysis on the Degree of Coupling Coordination Between Higher Education and Regional Economic Development in China: Take Sichuan Province of China as an Example

To explore the relationship between China's higher education and the level of regional economic development, the coupling coordination degree of panel data from China's Sichuan province across 2011-2018 is analyzed based on self-constructed evaluation index system and with a integration of various methods including entropy value method, coupling coordination degree model and grey forecasting model. The results show that the coupling coordination degree between higher education and economic development in five Sichuan districts is not high, among which Chengdu Plain Economic Zone is much higher than the other four: southern Sichuan Economic Zone, northeast Sichuan Economic Zone, Panxi Economic Zone and northwest Sichuan Ecological Demonstration Zone. The study also predicts that in the five years, the coupling coordination degree of the five districts in Sichuan will be still not high, and none of them will broke through the incoordinate stage and entered the coordination stage. Moreover, the difference between the prefecture-level cities in Chengdu Plain Economic Zone is the largest.

A 2000‐year spatiotemporal pattern and relationship between cities and floods in the Yangtze River Basin, China

AbstractThe Yangtze River is one of the most important rivers in China, and its basin is the most populous urban area in China. The relationship between cities and floods in the Yangtze River Basin is of significance. In our analysis of 4,511 historical county‐level cities and 37,512 historical flood disasters, we used ARCGIS to conduct spatial analyses, including kernel density analysis, coldspot and hotspot analysis, and center of gravity analysis, to reveal the relationship between cities, population, and floods in the Yangtze River Basin in the past 2000 years. The results indicate that three relatively stable, dense urban areas are the Chengdu Plain; the border of the Anhui, Zhejiang, Jiangsu Provinces and surrounding areas; and the central Guizhou Province and southwestern part of Hubei Province. The hotspot areas of floods were the main tributaries and lakes of the Yangtze River, whereas the coldspot areas were the Chengdu Plain and the surrounding areas. More importantly, cities are not far from flood regions, and this will cause serious flooding. Due to location advantages, cities tend to be close to rivers, lakes, and other water systems. This research provides historical details of urban development and ecological environment protection in the Yangtze River Basin in China.

Factors affecting cadmium accumulation in the soil profiles in an urban agricultural area

Soil Cd pollution is a serious environmental issue associated with human activities. However, the factors determining exogenous Cd dynamics in the soil profile in a complex environment are not well understood. Based on regional observations from 169 soil profiles across the Chengdu Plain, this study explored the key factors controlling Cd accumulation in the soil profile under actual field conditions. Results showed that total soil Cd contents decreased from 0.377 to 0.196 mg kg−1 with increasing soil depth. The effects of phosphate fertilizer rates, road density and precipitation on the difference in total soil Cd content were only observed in topsoil, while agricultural land-use type and topography had no impact. In contrast, significant differences in the total soil Cd content among different parent material types were found in the 0–20, 40–60 and 60–100 cm soil depths. One sample t-tests showed that significant Cd accumulation occurred in the whole soil profile in soils formed from Q4 (Quaternary Holocene) grey alluvium, while soils formed from Q3 (Quaternary Pleistocene) old alluvium and Q4 grey-brown alluvium showed significant Cd accumulation only in the 0–40 cm soil layers. In the topsoil, acid soluble Cd accounted for the largest proportion of the total Cd in soils formed from Q4 grey alluvium, reducible Cd was the main fraction in soils formed from Q4 grey-brown alluvium, while reducible Cd and residual Cd contributed the largest proportion of the total soil Cd in soils formed from Q3 old alluvium. The above results indicated that parent material was the decisive factor determining the magnitudes and depths of exogenous Cd accumulation in the soil profile due to its impacts on the Cd fraction distributions. These findings suggested that the parent material-induced Cd fraction distributions and accumulation should be considered for effectively exploring targeted remediation strategies for Cd pollution.