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Availability of precipitation data at high spatial and temporal resolution is crucial for the understanding of precipitation behaviors that are determinant for environmental aspects such as hydrology, ecology, and social aspects like agriculture, food security, or health issues. This study evaluates the performance of 3B42-V7 satellite-based precipitation product on extreme precipitation estimates in China, by using the Fuzzy C-Means algorithm and L-moment-based regional frequency analysis method. The China Gauge-based Daily Precipitation Analysis (CGDPA) product is employed to measure the estimation biases of 3B42-V7. Results show that: (1) for most regions of China, the Generalized Extreme Value and Generalized Normal distributions are preferable for extreme precipitation estimates; (2) the extreme precipitation estimations of 3B42-V7 for different return periods have a high correlation with those of CGDPA, with biases within 25% for a majority of China on extreme precipitation estimates.
Jiachao Chen; Zhaoli Wang; Xushu Wu; Chengguang Lai; Xiaohong Chen. Evaluation of TMPA 3B42-V7 Product on Extreme Precipitation Estimates. Remote Sensing 2021, 13, 209 .
AMA StyleJiachao Chen, Zhaoli Wang, Xushu Wu, Chengguang Lai, Xiaohong Chen. Evaluation of TMPA 3B42-V7 Product on Extreme Precipitation Estimates. Remote Sensing. 2021; 13 (2):209.
Chicago/Turabian StyleJiachao Chen; Zhaoli Wang; Xushu Wu; Chengguang Lai; Xiaohong Chen. 2021. "Evaluation of TMPA 3B42-V7 Product on Extreme Precipitation Estimates." Remote Sensing 13, no. 2: 209.
Landscape patterns have a substantial effect on non-point source (NPS) pollution in watersheds. Facilitating sustainable development of mountain-rural areas is a major priority for China. Knowledge of the impacts of various landscapes on water quality in these areas is critical to meeting environmental goals. This study applied the Soil and Water Assessment Tool (SWAT) to create a hydrologic and water quality model of the study watershed; then, the relationship between water quality and landscape patterns was investigated using multiple linear regression and redundancy analysis. The results show that the western sub-basins had higher nitrogen pollution loads, and the total nitrogen concentration reached a maximum value of 3.91 mg/L; the eastern sub-basins had a higher pollution load of phosphorous featured by maximum total phosphorous concentration of 2.15 mg/L. The water quality of the entire watershed in all scenarios tended to deteriorate over time. Landscape metrics accounted for 81.7% of the total variation in pollutant indicators. The percentage of forest landscape was negatively correlated with NPS pollution, while other types of landscape showed a positive correlation. The patch density, landscape shape index, and largest patch index of urban and agricultural lands were negatively correlated with pollutant concentrations. Upland landscapes contributed more pollutants than paddy fields. Some measures, e.g., returning grassland and farmland to forest in steep regions and replacing upland crops with paddy fields, were recommended for mitigating NPS pollution in the study watershed.
Wuhua Li; Xiangju Cheng; Yu Zheng; Chengguang Lai; David J. Sample; Dantong Zhu; Zhaoli Wang. Response of non-point source pollution to landscape pattern: case study in mountain-rural region, China. Environmental Science and Pollution Research 2021, 28, 16602 -16615.
AMA StyleWuhua Li, Xiangju Cheng, Yu Zheng, Chengguang Lai, David J. Sample, Dantong Zhu, Zhaoli Wang. Response of non-point source pollution to landscape pattern: case study in mountain-rural region, China. Environmental Science and Pollution Research. 2021; 28 (13):16602-16615.
Chicago/Turabian StyleWuhua Li; Xiangju Cheng; Yu Zheng; Chengguang Lai; David J. Sample; Dantong Zhu; Zhaoli Wang. 2021. "Response of non-point source pollution to landscape pattern: case study in mountain-rural region, China." Environmental Science and Pollution Research 28, no. 13: 16602-16615.
Soil erosion has become one of the most serious environmental problems worldwide, and rainfall is considered a crucial factor in water erosion. Rainfall erosivity is defined as the ability of precipitation to trigger soil erosion. The accurate assessment of rainfall erosivity is essential before taking appropriate measures to stop or slow down water erosion. In this study, we calculated the rainfall erosivity in China using the Xie model and two satellite-based precipitation products (SPPs). Gauge-based data from 2417 stations in China were used for a comparison of the results. We also proposed a procedure to assess the performance of the two SPPs using four statistical metrics and provided recommendations for different sub-regions at different time scales. The results showed that the annual rainfall erosivity based on the IMERG-F and TMPA 3B42V7 products and the in situ gauge stations were 2014, 1954, and 2138 MJ·mm/(hm2·h·yr), respectively. The spatial correlation between IMERG-F and situ gauge stations is 0.944 and that between the TMPA 3B42V7 product and situ gauge stations is 0.909. The variation trends of the two were highly similar to those of the gauge-based rainfall erosivity at all time scales. The TMPA 3B42V7 product is recommended for estimating rainfall erosivity in Haihe River Basin and Huaihe River Basin at monthly scale, in Haihe River Basin and China at seasonal scale, in the Haihe River Basin, Huaihe River Basin, Yellow River Basin at annual scale; while the IMERG-F is recommended for the remaining regions except Continental Basins at the three time scales. Generally, the IMERG-F has broader applicability than the TMPA 3B42V7 product for estimating rainfall erosivity in China. The results of this study provide a reference for selecting suitable SPPs for rainfall erosivity estimates.
Yuhong Chen; Menghua Xu; Zhaoli Wang; Ping Gao; Chengguang Lai. Applicability of two satellite-based precipitation products for assessing rainfall erosivity in China. Science of The Total Environment 2020, 757, 143975 .
AMA StyleYuhong Chen, Menghua Xu, Zhaoli Wang, Ping Gao, Chengguang Lai. Applicability of two satellite-based precipitation products for assessing rainfall erosivity in China. Science of The Total Environment. 2020; 757 ():143975.
Chicago/Turabian StyleYuhong Chen; Menghua Xu; Zhaoli Wang; Ping Gao; Chengguang Lai. 2020. "Applicability of two satellite-based precipitation products for assessing rainfall erosivity in China." Science of The Total Environment 757, no. : 143975.
In recent decades, the severe drought across agricultural regions of China has had significant impact on agriculture. The standardized precipitation evapotranspiration index (SPEI) has been widely used for drought analyses; however, SPEI is prone to be affected by potential evapotranspiration (PET). We thus examined the correlations between soil moisture anomalies and the SPEI calculated by the Thornthwaite, Hargreaves, and Penman–Monteith (PM) equations to select the most suitable for drought research. Additionally, the Mann–Kendall and wavelet analysis were used to investigate drought trends and to analyze and the impact of atmospheric circulation on drought in China from 1961 to 2018. The results showed that (1) PET obtained from the PM equation is the most suitable for SPEI calculation; (2) there were significant wetting trends in Northern China and the whole Chinese mainland and most of the wetting mutation points occurred in the 1970s and 1980s and the significant inter-annual oscillations period in the Chinese mainland was 2–4 years; (3) the Chinese mainland and Northern China are strongly influenced by West Pacific Trade Wind, while Western Pacific Subtropical High Intensity and Pacific Subtropical High Area have primary impact on Southern China.
Haowei Sun; Haiying Hu; Zhaoli Wang; Chengguang Lai. Temporal Variability of Drought in Nine Agricultural Regions of China and the Influence of Atmospheric Circulation. Atmosphere 2020, 11, 990 .
AMA StyleHaowei Sun, Haiying Hu, Zhaoli Wang, Chengguang Lai. Temporal Variability of Drought in Nine Agricultural Regions of China and the Influence of Atmospheric Circulation. Atmosphere. 2020; 11 (9):990.
Chicago/Turabian StyleHaowei Sun; Haiying Hu; Zhaoli Wang; Chengguang Lai. 2020. "Temporal Variability of Drought in Nine Agricultural Regions of China and the Influence of Atmospheric Circulation." Atmosphere 11, no. 9: 990.
Soil erosion has become one of the most serious global environmental and ecological crises. Rainfall erosivity measures the potential ability of precipitation to trigger soil erosion. This study estimated the degree of rainfall erosivity in mainland China from 1960 to 2018 using the Xie model and analyzed its spatiotemporal variability. The accuracy of the Xie model was reexamined and further verified with the use of data from densely distributed stations by comparing it with two typical daily models and an hourly model. The relationships between changes in rainfall erosivity and soil erosion were also discussed. Results showed that annual rainfall erosivity in mainland China ranged from 2 to 23,129 MJ⋅mm/(hm2⋅h⋅a) and decreased gradually from southeast to northwest. Annual rainfall erosivity also showed a significant increasing trend (P < 0.05) with a mean value of 3738 MJ⋅mm/(hm2⋅h⋅a) and a growth rate of 8 MJ·mm/((hm2·h·a)·a). The significant breakpoint (P < 0.05) occurred in 2002. Multiple oscillation periods were identified, but 3.5 years was identified as the main oscillation period. The Xie model was shown to be more accurate for estimating rainfall erosivity in mainland China because of its simple formula, which reduces computing time and the effort needed to make calculations. Therefore, the Xie model provides a robust daily model that could be widely used in mainland China. Although annual precipitation has reduced, the increasing concentration and intensity of precipitation appears to be the primary reason underlying the increase in rainfall erosivity. Efficient, economic, and environmental measures need to be taken to address some of the challenges of soil conservation in mainland China.
Yuhong Chen; Menghua Xu; Zhaoli Wang; Wenjie Chen; Chengguang Lai. Reexamination of the Xie model and spatiotemporal variability in rainfall erosivity in mainland China from 1960 to 2018. CATENA 2020, 195, 104837 .
AMA StyleYuhong Chen, Menghua Xu, Zhaoli Wang, Wenjie Chen, Chengguang Lai. Reexamination of the Xie model and spatiotemporal variability in rainfall erosivity in mainland China from 1960 to 2018. CATENA. 2020; 195 ():104837.
Chicago/Turabian StyleYuhong Chen; Menghua Xu; Zhaoli Wang; Wenjie Chen; Chengguang Lai. 2020. "Reexamination of the Xie model and spatiotemporal variability in rainfall erosivity in mainland China from 1960 to 2018." CATENA 195, no. : 104837.
Flooding is a major natural disaster that has brought tremendous losses to mankind throughout the ages. Even so, floods can be controlled by appropriate measures to minimize loss and damage. Flood risk assessment is an essential analytic step in preventing floods and reducing losses. Identifying previous flood risk and predicting future features are conducive to understanding the changing patterns and laws of flood risk. Taking the Dongjiang River basin as a study case, we assessed and regionalized flood risk in 1990, 2000, and 2010 from the past perspective and explored dynamic expansion during 1990–2010. Then, we projected land‐use type, population, and gross domestic product in 2030 and 2050 and finally assessed and regionalized the risk from a future perspective. Results show that areas with very high risk accounted for 14.98–18.08% during 1990–2010; approximately 13.90% areas of the basin transformed from lower‐level risk to higher‐level risk whereas 9.07% fell from a higher level to a lower level during the period. For the future scenario, areas with very high and high risk in 2030 and 2050 are expected to account for 21.55% and 24.84%, respectively. Generally, our study can better identify changes in flood risk at a spatial scale and reveal the dynamic evolution rule, which provides a synthetical means of flood prevention and reduction, flood insurance, urban planning, and water resource management in the future under global climate change, especially for developing or high‐speed urbanization regions.
Chengguang Lai; Xiaohong Chen; Zhaoli Wang; Haijun Yu; Xiaoyan Bai. Flood Risk Assessment and Regionalization from Past and Future Perspectives at Basin Scale. Risk Analysis 2020, 40, 1399 -1417.
AMA StyleChengguang Lai, Xiaohong Chen, Zhaoli Wang, Haijun Yu, Xiaoyan Bai. Flood Risk Assessment and Regionalization from Past and Future Perspectives at Basin Scale. Risk Analysis. 2020; 40 (7):1399-1417.
Chicago/Turabian StyleChengguang Lai; Xiaohong Chen; Zhaoli Wang; Haijun Yu; Xiaoyan Bai. 2020. "Flood Risk Assessment and Regionalization from Past and Future Perspectives at Basin Scale." Risk Analysis 40, no. 7: 1399-1417.
Floods are generally considered to be the most common natural disaster worldwide. Climate change and human activity are two key driving factors of flood formation, and it is difficult to determine how to quantitatively detect their relative impacts on flood susceptibility. As an important non-engineering measure of preventing floods and reducing losses, flood susceptibility assessment is a synthetic task that involves many factors. In this study, the flood susceptibility in Guangdong Province, China, was assessed based on a cloud model. The relative impacts of climate change and human activity on flood susceptibility were also quantitatively investigated from the spatial perspective. The results prove that the cloud model is a feasible, reasonable, and effective method for flood susceptibility assessment. Approximately 40% of the studied areas have changed their flood susceptibility level since 1985 due to the comprehensive impacts of climate change and human activity, of which about 56.3% converted from a low to high level, and 43.7% from a high to low level. About 35.7% of the areas changed their susceptibility level due to climate change, of which 55.8% converted from a low to high level and 44.2% from a high to low level. In contrast, only 9.8% of the areas changed the susceptibility level due to human activity, of which 57.2% converted from a low to high level and 42.8% from a high to low level. Generally, from the spatial perspective, climate change has a larger impact on flood susceptibility than human activity. This study aims to provide a novel idea to quantitatively detect the relative impacts of climate change and human activity on flood susceptibility from spatial perspective; the findings of this study are also expected to enhance the understanding on distribution rule of flood susceptibility in Guangdong Province and are conducive to taking targeted measures to reduce the flood risk.
Shanshan Li; Zhaoli Wang; Chengguang Lai; Guangsi Lin. Quantitative assessment of the relative impacts of climate change and human activity on flood susceptibility based on a cloud model. Journal of Hydrology 2020, 588, 125051 .
AMA StyleShanshan Li, Zhaoli Wang, Chengguang Lai, Guangsi Lin. Quantitative assessment of the relative impacts of climate change and human activity on flood susceptibility based on a cloud model. Journal of Hydrology. 2020; 588 ():125051.
Chicago/Turabian StyleShanshan Li; Zhaoli Wang; Chengguang Lai; Guangsi Lin. 2020. "Quantitative assessment of the relative impacts of climate change and human activity on flood susceptibility based on a cloud model." Journal of Hydrology 588, no. : 125051.
Sunshine duration (SD) is a key index with which to quantitatively measure the intensity and duration of solar radiation. The exploration of spatiotemporal characteristics and potential influential factors for SD could help us better understand solar radiation variability. In this study, we first explore the spatiotemporal variability of SD across mainland China during 1959‐2017, then identify the predominant influential climatic factors and detect their relative influence of temporal dynamic on SD, and finally discuss the relative influential rates of climatic factors and detect the dominating climatic factor on a spatial scale. The results show that: 1) the annual and seasonal SD gradually decreased from the northwest to southeast across mainland China; a significant decreasing trend (P < 0.05) was detected for annual SD at a rate of ‐2.7 h/a, a turning point significantly occurred in 1986 (P< 0.05) in the year SD series, and oscillation periods of 2.4‐3.8 years existed in mainland China and most sub‐regions. 2) The significant (P < 0.05) decrease of wind speed (Win), increase of precipitation (Pre), and increase of vapor pressure (Vp) were responsible for the decreasing trend of SD with relative influential rates of 39.9%, 30.6%, and 29.5%, respectively. 3) Temporally, the relative influential rate of each climatic variable changed over time; spatially, Win dominated most areas of mainland China (55.9%) during 1959‐2017, followed by Pre (24.9%) and Vp (19.2%). Keywords: sunshine duration; spatiotemporal variability; influential climatic factors; random forest.
Jinghua Xiong; Zhaoli Wang; Chengguang Lai; Yaoxing Liao; Xushu Wu. Spatiotemporal variability of sunshine duration and influential climatic factors in mainland China during 1959–2017. International Journal of Climatology 2020, 40, 6282 -6300.
AMA StyleJinghua Xiong, Zhaoli Wang, Chengguang Lai, Yaoxing Liao, Xushu Wu. Spatiotemporal variability of sunshine duration and influential climatic factors in mainland China during 1959–2017. International Journal of Climatology. 2020; 40 (15):6282-6300.
Chicago/Turabian StyleJinghua Xiong; Zhaoli Wang; Chengguang Lai; Yaoxing Liao; Xushu Wu. 2020. "Spatiotemporal variability of sunshine duration and influential climatic factors in mainland China during 1959–2017." International Journal of Climatology 40, no. 15: 6282-6300.
The analysis of the impact of drought events on terrestrial net primary productivity (NPP) is significant to understand the effects of droughts on regional/global carbon cycling. During the past three decades, terrestrial ecosystems in mainland China have been frequently impacted by drought events. However, quantitative analyses of the variation of NPP induced by droughts are still not enough. Therefore, this study explored the response of NPP to drought events from 1982 to 2015 based on the standardized evapotranspiration deficit index (SEDI) and an NPP dataset obtained from the Carnegie-Ames-Stanford Approach model. We first identified drought events and analyzed the characteristics of drought events using a three-dimensional clustering algorithm. Subsequently, we determined the NPP variations in the drought-affected areas during the droughts and explored the correlation between the NPP variation and the drought characteristics. The results showed that 152 persistent drought events lasting at least 3 months were identified. Most events had durations between 3 and 5 months, and 19 events lasted >9 months. A negative NPP was detected in >60% of the drought-affected areas during long-term (>6 months) and severe (>4 × 106 km2 month) drought events and the total NPP showed a clear decrease during these events. In general, strong drought events reduced the total NPP by >30 TgC in the Northern Region, South Region, Southwest Region, and Northeast Region. The substantial decrease was mainly caused by the NPP anomaly from April to September. The NPP responses to drought events exhibited differences due to different drought characteristics. Although a high proportion of the drought-affected areas experienced a decrease in NPP during most short-term (<5 months) and less severe droughts (<2 × 106 km2 month), the total NPP did not exhibit a large change during these events.
Jun Li; Zhaoli Wang; Chengguang Lai. Severe drought events inducing large decrease of net primary productivity in mainland China during 1982–2015. Science of The Total Environment 2020, 703, 135541 .
AMA StyleJun Li, Zhaoli Wang, Chengguang Lai. Severe drought events inducing large decrease of net primary productivity in mainland China during 1982–2015. Science of The Total Environment. 2020; 703 ():135541.
Chicago/Turabian StyleJun Li; Zhaoli Wang; Chengguang Lai. 2020. "Severe drought events inducing large decrease of net primary productivity in mainland China during 1982–2015." Science of The Total Environment 703, no. : 135541.
Extending series of river streamflow based on tree-ring reconstruction is of scientific and practical importance for understanding hydrological or meteorological change of past. To achieve more accurate reconstructions, the intelligent learning algorithm random forest (RF) was proposed in this study to reconstruct the annual streamflow of the source region of the Yangtze River (SRYR). The method was developed using tree-ring chronologies ranging from 1485 to 2000 (AD) and annual streamflow from 1956 to 2000 (AD). The relationship between streamflow and the main large-scale atmospheric circulation as well as solar activity has also been discussed. The results show that: a) RF model could capture a more realistic characteristic of streamflow and show higher predictive ability for streamflow reconstruction than bagged regression trees (BRT), support vector machine (SVM), and simple linear regression (SLM). b) A period of lower streamflow occurred during the late 16th and mid-18th centuries, and the early 19th and mid-20th centuries experienced higher streamflow; an interesting temporal pattern indicated that the instrumental period was representative of individual highest (1979) and lowest (1989) streamflow years; in addition, a 2–8-year significant periodical oscillation (at 95% confidence level) was observed over most of the reconstructed series, with dominant periods of 2.5- and 4.9-year. c) The variability of streamflow in the study area was strongly associated with Pacific Decadal Oscillation (PDO), El Nino-Southern Oscillation (ENSO) and solar activity. This study provides reference for streamflow reconstruction based on tree-ring data and helps to understand the hydrological variation of past in SRYR.
Jun Li; Zhaoli Wang; Chengguang Lai; Zhenxing Zhang. Tree-ring-width based streamflow reconstruction based on the random forest algorithm for the source region of the Yangtze River, China. CATENA 2019, 183, 104216 .
AMA StyleJun Li, Zhaoli Wang, Chengguang Lai, Zhenxing Zhang. Tree-ring-width based streamflow reconstruction based on the random forest algorithm for the source region of the Yangtze River, China. CATENA. 2019; 183 ():104216.
Chicago/Turabian StyleJun Li; Zhaoli Wang; Chengguang Lai; Zhenxing Zhang. 2019. "Tree-ring-width based streamflow reconstruction based on the random forest algorithm for the source region of the Yangtze River, China." CATENA 183, no. : 104216.
With a high spatial resolution and wide coverage, satellite-based precipitation products have compensated for the shortcomings of traditional measuring methods based on rain gauge stations, such as the sparse and uneven distribution of rain gauge stations. However, the accuracy of satellite precipitation products is not high enough in some areas, and the causes of their errors are complicated. In order to better calibrate and apply the product’s data, relevant research on this kind of product is required. Accordingly, this study investigated the spatial error distribution and spatial influence factors of the Tropical Rainfall Measuring Mission (TRMM) Multi-Satellite Precipitation Analysis (TMPA) post-process 3B42V7 (hereafter abbreviated as 3B42V7) data over mainland China. This study calculated accuracy indicators based on the 3B42V7 data and daily precipitation data from 797 rain gauge stations across mainland China over the time range of 1998–2012. Then, a clustering analysis was conducted based on the accuracy indicators. Moreover, the geographical detector (GD) was used to perform the error cause analysis of the 3B42V7. The main findings of this study are the following. (1) Within mainland China, the 3B42V7 data accuracy decreased gradually from the southeast coast to the northwest inland, and shows a similar distribution for precipitation. High values of systematic error (>1.0) is mainly concentrated in the southwest Tibetan Plateau, while high values of random error (>1.0) are mainly concentrated around the Tarim Basin. (2) Mainland China can be divided into three areas by the spectral clustering method. It is recommended that the 3B42V7 can be effectively used in Area I, while in Area III the product should be calibrated before use, and the product in Area II can be used after an applicability study. (3) The GD result shows that precipitation is the most important spatial factor among the seven factors influencing the spatial error distribution of the 3B42V7 data. The relationships between spatial factors are synergistic rather than individual when influencing the product’s accuracy.
Zifeng Deng; Zhaoli Wang; Chengguang Lai. Spatial Error Distribution and Error Cause Analysis of TMPA-3B42V7 Satellite-Based Precipitation Products over Mainland China. Water 2019, 11, 1435 .
AMA StyleZifeng Deng, Zhaoli Wang, Chengguang Lai. Spatial Error Distribution and Error Cause Analysis of TMPA-3B42V7 Satellite-Based Precipitation Products over Mainland China. Water. 2019; 11 (7):1435.
Chicago/Turabian StyleZifeng Deng; Zhaoli Wang; Chengguang Lai. 2019. "Spatial Error Distribution and Error Cause Analysis of TMPA-3B42V7 Satellite-Based Precipitation Products over Mainland China." Water 11, no. 7: 1435.
This study mainly evaluated and compared satellite-based quantitative precipitation estimate products (QPEs) for the drought monitoring of mainland China. Two long-term (more than 30 a) satellite-based QPEs, i.e. the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record (PERSIANN-CDR) and the Climate Hazards Group InfraRed Precipitation with Station (CHIRPS), and a short-term (18a) QPE, i.e. the Tropical Rainfall Measuring Mission (TRMM) Multi-Satellite Precipitation Analysis (TMPA) 3B42V7 are considered. Two widely used drought indices, the Standardized Precipitation Index (SPI) and the Palmer Drought Severity Index (PDSI), are chosen to evaluate the drought monitoring utility. The 3B42V7 was only evaluated with PDSI due to the short data records. The results show that all the three QPEs perform satisfactorily in the eastern part of China when using both SPI and PDSI. However, their performances for west China could not be clearly determined due to the sparse gauge networks. 3B42V7 features best performance among the three QPEs in the evaluation using PDSI. To further spatiotemporally evaluate the drought utility of the QPEs, four typical drought-affected regions, i.e. northeast China (NEC), Huang-Huai-Hai plain (3HP), southwest China (SWC), and Loess plateau (LP) were extracted from mainland China for specific case studies. Temporally, all three QPEs are able to detect the typical drought of the four regions with both SPI and PDSI, and 3B42V7 presents the least deviation in PDSI estimate. Spatially, both CHIRPS and 3B42V7 accurately catch the spatial centers and extent of the typical drought events, while PERSIANN-CDR could not match the spatial patterns of drought events well. Generally, the long-term PERSIANN-CDR and CHIRPS perform satisfactorily in drought detection and are suitable for drought utility; however, caution should be applied when studying the spatial variation of drought using PERSIANN-CDR. CHIRPS could also be suitable for near-real-time drought monitoring for its shorter time latency of data release. The short-term 3B42V7 also performs well in many cases, and has thus considerable potential for drought monitoring.
Ruida Zhong; Xiaohong Chen; Chengguang Lai; Zhaoli Wang; Yanqing Lian; Haijun Yu; Xiaoqing Wu. Drought monitoring utility of satellite-based precipitation products across mainland China. Journal of Hydrology 2018, 568, 343 -359.
AMA StyleRuida Zhong, Xiaohong Chen, Chengguang Lai, Zhaoli Wang, Yanqing Lian, Haijun Yu, Xiaoqing Wu. Drought monitoring utility of satellite-based precipitation products across mainland China. Journal of Hydrology. 2018; 568 ():343-359.
Chicago/Turabian StyleRuida Zhong; Xiaohong Chen; Chengguang Lai; Zhaoli Wang; Yanqing Lian; Haijun Yu; Xiaoqing Wu. 2018. "Drought monitoring utility of satellite-based precipitation products across mainland China." Journal of Hydrology 568, no. : 343-359.
Bingjun Liu; Zeqin Huang; Xiuhong Chen; Zhaoli Wang. Effects of large-scale climate anomalies on crop reference evapotranspiration in the main grain-production area of China. International Journal of Climatology 2018, 39, 1195 -1212.
AMA StyleBingjun Liu, Zeqin Huang, Xiuhong Chen, Zhaoli Wang. Effects of large-scale climate anomalies on crop reference evapotranspiration in the main grain-production area of China. International Journal of Climatology. 2018; 39 (3):1195-1212.
Chicago/Turabian StyleBingjun Liu; Zeqin Huang; Xiuhong Chen; Zhaoli Wang. 2018. "Effects of large-scale climate anomalies on crop reference evapotranspiration in the main grain-production area of China." International Journal of Climatology 39, no. 3: 1195-1212.
Land use and land cover patterns in mainland China have substantially changed in the recent decades under the economic reform policies of the government. The terrestrial carbon cycle, particularly the net primary productivity (NPP), has been substantially changed on both local and national scales. With the growing concern over the effects of the terrestrial carbon cycle on global climate changes, the impacts of land use and cover change (LUCC) on NPP need to be understood. In this study, variations in NPP caused by LUCC (e.g., urbanization and conversion of other land use to forest and grassland) in mainland China from the late 1980s to 2015 were evaluated based on land cover datasets and NPPs simulated from the Carnegie–Ames–Stanford Approach model. The results indicate that the national total losses in NPP attributed to urbanization reached 1.695 TgC between the late 1980s and 2015. A large proportion (63.02%) of the total losses was due to the transformation from cropland to urban land. Urban expansion decreased the monthly and total NPPs over southern China, which includes the South China Region, Southwest China Region, and the middle and lower regions of the Yangtze River. However, the total NPP increased in the majority of urbanized areas in Northern China, including the Huang–Huai–Hai Region, Inner Mongolia Region (MGR), Gan-Xin Region (GXR), and Northeast China Region; monthly NPP in GXR and MGR increased throughout the year. By contrast, the conversion to grassland or forestland increased the monthly and total NPPs of Northern China, suggesting that returning to forestland and grassland could increase the carbon sequestration capacity of terrestrial ecosystems in mainland China. Among the sub-regions, the Loess Plateau Region contributed the largest increase in NPP, which was prompted by the conversion to grassland and forestland.
Jun Li; Zhaoli Wang; Chengguang Lai; Xiaoqing Wu; Zhaoyang Zeng; Xiaohong Chen; Yanqing Lian. Response of net primary production to land use and land cover change in mainland China since the late 1980s. Science of The Total Environment 2018, 639, 237 -247.
AMA StyleJun Li, Zhaoli Wang, Chengguang Lai, Xiaoqing Wu, Zhaoyang Zeng, Xiaohong Chen, Yanqing Lian. Response of net primary production to land use and land cover change in mainland China since the late 1980s. Science of The Total Environment. 2018; 639 ():237-247.
Chicago/Turabian StyleJun Li; Zhaoli Wang; Chengguang Lai; Xiaoqing Wu; Zhaoyang Zeng; Xiaohong Chen; Yanqing Lian. 2018. "Response of net primary production to land use and land cover change in mainland China since the late 1980s." Science of The Total Environment 639, no. : 237-247.
Terrestrial net primary productivity (NPP) plays an essential role in the global carbon cycle as well as for climate change. However, in the past three decades, terrestrial ecosystems across mainland China suffered from frequent drought and, to date, the adverse impacts on NPP remain uncertain. This study explored the spatiotemporal features of NPP and discussed the influences of drought on NPP across mainland China from 1982 to 2015 using the Carnegie Ames Stanford Application (CASA) model and the standardized precipitation evapotranspiration index (SPEI). The obtained results indicate that: (1) The total annual NPP across mainland China showed an non-significantly increasing trend from 1982 to 2015, with annual increase of 0.025 Pg C; the spring NPP exhibited a significant increasing trend (0.031 Pg C year−1, p < 0.05) while the summer NPP showed a higher decreasing trend (0.019 Pg C year−1). (2) Most areas of mainland China were spatially dominated by a positive correlation between annual NPP and SPEI and a significant positive correlation was mainly observed for Northern China; specific to the nine sub-regions, annual NPP and SPEI shared similar temporal patterns with a significant positive relation in Northeastern China, Huang-Huai-Hai, Inner Mongolia, and the Gan-Xin Region. (3) During the five typical drought events, more than 23% areas of mainland China experienced drought ravage; the drought events generally caused about 30% of the NPP reduction in most of the sub-regions while the NPP in the Qinghai-Tibet Plateau Region generally decreased by about 10%.
Chengguang Lai; Jun Li; Zhaoli Wang; Xiaoqing Wu; Zhaoyang Zeng; Xiaohong Chen; Yanqing Lian; Haijun Yu; Peng Wang; Xiaoyan Bai. Drought-Induced Reduction in Net Primary Productivity across Mainland China from 1982 to 2015. Remote Sensing 2018, 10, 1433 .
AMA StyleChengguang Lai, Jun Li, Zhaoli Wang, Xiaoqing Wu, Zhaoyang Zeng, Xiaohong Chen, Yanqing Lian, Haijun Yu, Peng Wang, Xiaoyan Bai. Drought-Induced Reduction in Net Primary Productivity across Mainland China from 1982 to 2015. Remote Sensing. 2018; 10 (9):1433.
Chicago/Turabian StyleChengguang Lai; Jun Li; Zhaoli Wang; Xiaoqing Wu; Zhaoyang Zeng; Xiaohong Chen; Yanqing Lian; Haijun Yu; Peng Wang; Xiaoyan Bai. 2018. "Drought-Induced Reduction in Net Primary Productivity across Mainland China from 1982 to 2015." Remote Sensing 10, no. 9: 1433.
To evaluate the accuracy and applicability of the TMPA 3B42-V7 precipitation product for the Lancang River basin, we used different statistical indices to explore the performance of the product in comparison to gauge data. Then, we performed a hydrologic simulation using the Variable Infiltration Capacity (VIC) hydrological model with two scenarios (Scenario I: streamflow simulation using gauge-calibrated parameters; Scenario II: streamflow simulation using 3B42-V7-recalibrated parameters) to verify the applicability of the product. The results of the precipitation analysis show good accuracy of the V7 precipitation data. The accuracy increases with the increase of both space and time scales, while time scale increases cause a stronger effect. The satellite can accurately measure most of the precipitation but tends to misidentify non-precipitation events as light precipitation events (<1 mm/day). The results of the hydrologic simulation show that the VIC hydrological model has good applicability for the Lancang River basin. However, 3B42-V7 data did not perform as well under Scenario I with the lowest Nash–Sutcliffe coefficient of efficiency (NSCE) of 0.42; Scenario II suggests that the error drops significantly and the NSCE increases to 0.70 or beyond. In addition, the simulation accuracy increases with increased temporal scale.
Zhaoli Wang; Jiachao Chen; Chengguang Lai; Ruida Zhong; Xiaohong Chen; Haijun Yu. Hydrologic assessment of the TMPA 3B42-V7 product in a typical alpine and gorge region: the Lancang River basin, China. Water Policy 2018, 49, 2002 -2015.
AMA StyleZhaoli Wang, Jiachao Chen, Chengguang Lai, Ruida Zhong, Xiaohong Chen, Haijun Yu. Hydrologic assessment of the TMPA 3B42-V7 product in a typical alpine and gorge region: the Lancang River basin, China. Water Policy. 2018; 49 (6):2002-2015.
Chicago/Turabian StyleZhaoli Wang; Jiachao Chen; Chengguang Lai; Ruida Zhong; Xiaohong Chen; Haijun Yu. 2018. "Hydrologic assessment of the TMPA 3B42-V7 product in a typical alpine and gorge region: the Lancang River basin, China." Water Policy 49, no. 6: 2002-2015.
A rapid increase in the risk of urban flooding in recent years has urged the research community to enrich approaches to deal with urban flooding problems. The state-of-the-art approach consists of coupling one-dimensional (1D) and two-dimensional (2D) hydrodynamic models. However, at present such coupled 1D/2D models are mostly commercial and complex to build and run. The present study has proposed a new simple approach for modeling urban flooding by coupling Storm Water Management Model (SWMM) and LISFLOOD-FP, two widely used freewares with relatively simple components. The coupled model was firstly applied to the Shiqiao Creek District in Dongguan City, South China, and verified against four major historical floods. The testing results demonstrate the capability of the coupled model in predicting urban flooding. The successful coupling of SWMM and LISFLOOD-FP offers another simple, practical approach for urban flooding estimation, which can be readily used by non-expert users or those who do not have access to commercial modules.
Xushu Wu; Zhaoli Wang; Shenglian Guo; Chengguang Lai; Xiaohong Chen. A simplified approach for flood modeling in urban environments. Hydrology Research 2018, 49, 1804 -1816.
AMA StyleXushu Wu, Zhaoli Wang, Shenglian Guo, Chengguang Lai, Xiaohong Chen. A simplified approach for flood modeling in urban environments. Hydrology Research. 2018; 49 (6):1804-1816.
Chicago/Turabian StyleXushu Wu; Zhaoli Wang; Shenglian Guo; Chengguang Lai; Xiaohong Chen. 2018. "A simplified approach for flood modeling in urban environments." Hydrology Research 49, no. 6: 1804-1816.
Climate change and human activity are typically regarded as the two most important factors affecting runoff. Quantitative evaluation of the impact of climate change and human activity on runoff is important for the protection, planning, and management of water resources. This study assesses the contributions of climate change and human activity to runoff change in the Dongjiang River basin from 1960 to 2005 by using linear regression, the Soil and Water Assessment Tool (SWAT) hydrologic model, and the climate elasticity method. Results indicate that the annual temperature in the basin significantly increased, whereas the pan evaporation in the basin significantly decreased (95%). The natural period ranged from 1960 to 1990, and the affected period ranged from 1991 to 2005. The percentage of urban area during the natural period, which was 1.94, increased to 4.79 during the affected period. SWAT modeling of the Dongjiang River basin exhibited a reasonable and reliable performance. The impacts induced by human activity on runoff change were as follows: 39% in the upstream area, 13% in the midstream area, 77% in the downstream area, and 42% in the entire basin. The impacts of human activity on runoff change were greater in the downstream area than in either upstream and midstream areas. However, the contribution of climate change (58%) is slightly larger than that of human activity (42%) in the whole basin.
Yuliang Zhou; Chengguang Lai; Zhaoli Wang; Xiaohong Chen; Zhaoyang Zeng; Jiachao Chen; Xiaoyan Bai. Quantitative Evaluation of the Impact of Climate Change and Human Activity on Runoff Change in the Dongjiang River Basin, China. Water 2018, 10, 571 .
AMA StyleYuliang Zhou, Chengguang Lai, Zhaoli Wang, Xiaohong Chen, Zhaoyang Zeng, Jiachao Chen, Xiaoyan Bai. Quantitative Evaluation of the Impact of Climate Change and Human Activity on Runoff Change in the Dongjiang River Basin, China. Water. 2018; 10 (5):571.
Chicago/Turabian StyleYuliang Zhou; Chengguang Lai; Zhaoli Wang; Xiaohong Chen; Zhaoyang Zeng; Jiachao Chen; Xiaoyan Bai. 2018. "Quantitative Evaluation of the Impact of Climate Change and Human Activity on Runoff Change in the Dongjiang River Basin, China." Water 10, no. 5: 571.
Water quality evaluation is an essential measure to analyze water quality. However, excessive randomness and fuzziness affect the process of evaluation, thus reducing the accuracy of evaluation. Therefore, this study proposed a cloud model for evaluating the water quality to alleviate this problem. Analytic hierarchy process and entropy theory were used to calculate the subjective weight and objective weight, respectively, and then they were coupled as a combination weight (CW) via game theory. The proposed game theory-based cloud model (GCM) was then applied to the Qixinggang section of the Beijiang River. The results show that the CW ranks fecal coliform as the most important factor, followed by total nitrogen and total phosphorus, while biochemical oxygen demand and fluoride were considered least important. There were 19 months (31.67%) at grade I, 39 months (65.00%) at grade II, and one month at grade IV and grade V during 2010–2014. A total of 52 months (86.6%) of GCM were identical to the comprehensive evaluation result (CER). The obtained water quality grades of GCM are close to the grades of the analytic hierarchy process weight (AHPW) due to the weight coefficient of AHPW set to 0.7487. Generally, one or two grade gaps exist among the results of the three groups of weights, suggesting that the index weight is not particularly sensitive to the cloud model. The evaluated accuracy of water quality can be improved by modifying the quantitative boundaries. This study could provide a reference for water quality evaluation, prevention, and improvement of water quality assessment and other applications.
Bing Yang; Chengguang Lai; Xiaohong Chen; Xiaoqing Wu; Yanhu He. Surface Water Quality Evaluation Based on a Game Theory-Based Cloud Model. Water 2018, 10, 510 .
AMA StyleBing Yang, Chengguang Lai, Xiaohong Chen, Xiaoqing Wu, Yanhu He. Surface Water Quality Evaluation Based on a Game Theory-Based Cloud Model. Water. 2018; 10 (4):510.
Chicago/Turabian StyleBing Yang; Chengguang Lai; Xiaohong Chen; Xiaoqing Wu; Yanhu He. 2018. "Surface Water Quality Evaluation Based on a Game Theory-Based Cloud Model." Water 10, no. 4: 510.
Drought is considered an environmental disaster with a direct and devastating impact on agriculture. However, little research focuses on climate change related drought variations across the global grain production area (GGPA). Thus, the variation of crop yield across different grain production regions that experience severe drought remains inadequately studied. We analyzed drought variations across the GGPA to study the impacts of severe droughts on the yields of four major crops (maize, rice, wheat, and soybean). This analysis was based on the Standardized Precipitation Evapotranspiration Index (SPEI) and the crop yield dataset from 1951 to 2011. The results indicated that the entire GGPA experienced a significant increase in drought duration, impacted area, and severity of hazards. There was an average of 2.2 dry months and the dry area increased by 1.109% per decade. Regional variations existed across the GGPA, although the majority presented a tendency to increasing drought. Southern and Northern America tended to become wetter, while Eastern Asia, Southern Europe, and Africa (except for Eastern Africa) tended to become dryer. Developing countries and regions are generally more susceptible to extreme droughts and suffer more losses than developed countries and regions.
Zhaoli Wang; Jun Li; Chengguang Lai; Raymond Yu Wang; Xiaohong Chen; Yanqing Lian. Drying tendency dominating the global grain production area. Global Food Security 2018, 16, 138 -149.
AMA StyleZhaoli Wang, Jun Li, Chengguang Lai, Raymond Yu Wang, Xiaohong Chen, Yanqing Lian. Drying tendency dominating the global grain production area. Global Food Security. 2018; 16 ():138-149.
Chicago/Turabian StyleZhaoli Wang; Jun Li; Chengguang Lai; Raymond Yu Wang; Xiaohong Chen; Yanqing Lian. 2018. "Drying tendency dominating the global grain production area." Global Food Security 16, no. : 138-149.