| 1. |
- Sun, Huaiwei, et al.
(författare)
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Different types of meteorological drought and their impact on agriculture in Central China
- 2023
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Ingår i: Journal of Hydrology. - 0022-1694. ; 627
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Tidskriftsartikel (refereegranskat)abstract
- Challenges in drought monitoring hinder social development. In this study, a robust drought monitoring framework composed of ten indicators was established based on the standard precipitation actual evapotranspiration (SPAEI) index calculated using the maximum entropy production (MEP) model. Additionally, the relationship between meteorological drought and agricultural development was analyzed. The results indicated that the seasonal SPAEI performed better than the standardized precipitation evapotranspiration index (SPEI) in terms of drought area, vegetation drought, and drought identification in Central China. The annual drought duration was between 3.4 and 4.5 months, and the annual drought frequency ranged from 1.1 to 1.9 times per year. The main drought pattern was divided into persistent light drought and short-term severe drought, with the latter dominating crop yields in Central China. Although persistent light drought contributes more to drought, short-term severe drought has a greater impact on crop yields. Thoroughly investigating regional drought patterns and assessing their impacts on agriculture will contribute to a better understanding of drought characteristics and provide valuable guidance for regional agricultural water resource allocation and management.
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| 2. |
- Du, Shixiong, et al.
(författare)
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Evaluating the potential benefits of float solar photovoltaics through the water footprint recovery period
- 2024
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Ingår i: Journal of Cleaner Production. - 0959-6526. ; 446
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Tidskriftsartikel (refereegranskat)abstract
- In the context of higher demands on the development of clean energy technologies due to the issue of water shortage in China and the implementation of the 2060 carbon-neutral objective, floating photovoltaic (FPV) systems present novel opportunities for transforming the energy structure through land conservation and enhancement of power generation efficiency compared to conventional solar systems. However, there is currently a lack of comprehensive analysis on the potential benefits of FPV. Utilizing reservoir databases and employing a professional FPV system design, a methodology for determining the water footprint recovery period was introduced, which enables the assessment of potential FPV benefits. The water footprint recovery period for constructing FPV on 909 reservoirs in China was found that ranges from 1.86 yr to 10.48 yr. It is found that reservoir evaporation, latitude, and climate are closely related to the water footprint recovery period of FPV. Furthermore, by implementing FPV panels with an optimal tilt angle, covering 30% of the area in each reservoir, the annual electricity generation can amount to 1429.19 TWh, leading to savings of 5.76 billion m3 of water. This achievement corresponds to 19.41% of the national electricity consumption and a 6.86% reduction in the national residential water consumption in 2020. The overall economic benefit is 5.61 myriads RMB, equivalent to 5.76% of the national GDP. These benefits are unevenly distributed and mainly concentrated in areas with more reservoirs. The anticipated enhancement of FPV system benefits is foreseen with the ongoing development and implementation of future reservoir power infrastructure and energy storage technology. These results demonstrate the significant potential of installing FPV systems on the reservoirs in China. This study proposes a method to comprehensively evaluate the comprehensive benefits of constructing FPV in China and conduct a thorough analysis of the feasibility of FPV, which could provide reference for the development of regional industries and the achievement of sustainable development goals (SDGs).
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| 3. |
- Du, Shixiong, et al.
(författare)
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Projection of Precipitation Extremes and Flood Risk in the China–Pakistan Economic Corridor
- 2022
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Ingår i: Frontiers in Environmental Science. - : Frontiers Media SA. - 2296-665X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- It is reported that the China–Pakistan Economic Corridor has been affected by extreme precipitation events. Since the 20th century, extreme weather events have occurred frequently, and the damage and loss caused by them have increased. In particular, the flood disaster caused by excessive extreme precipitation seriously hindered the development of the human society. Based on CRiteria Importance Through Intercriteria Correlation and square root of generalized cross-validation, this study used intensity–area–duration to analyze the trend of future extreme precipitation events, corrected the equidistance cumulative distribution function method deviation of different future scenario models (CESM2, CNRM-CM6-1, IPSL-CM6A-LR, and MIROC6) and evaluated the simulation ability of the revised model. The results showed that: 1) the deviation correction results of CNRM-CM6-1 in the Coupled Model Intercomparison Project Phase (CMIP) 6 could better simulate the precipitation data in the study area, and its single result could achieve the fitting effect of the CMIP5 multimodel ensemble average; 2) under CNRM-CM6-1, the frequency of extreme precipitation events under the three climate scenarios (SSP1-2.6, SSP3-7.0, and SSP5-8.5) presents interdecadal fluctuations of 3.215 times/10A, 1.215 times/10A, and 5.063 times/10A, respectively. The average impact area of extreme precipitation events would decrease in the next 30 years, while the total impact area and the extreme precipitation events in a small range would increase. Under the future scenario, the increase rate of extreme precipitation was highest in August, which increased the probability of extreme events; 3) in the next 30 years, the flood risk had an obvious expansion trend, which was mainly reflected in the expansion of the area of high-, medium-, and low-risk areas. The risk zoning results obtained by the two different flood risk assessment methods were different, but the overall risk trend was the same. This study provided more advanced research for regional flood risk, reasonable prediction for flood risk under future climate models, and useful information for flood disaster prediction in the study area and contributes to the formulation of local disaster prevention and reduction policies.
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| 4. |
- Lu, Mengge, et al.
(författare)
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Projections of thermal growing season indices over China under global warming of 1.5 °C and 2.0 °C
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 781
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Tidskriftsartikel (refereegranskat)abstract
- Global warming may prolong and intensify the thermal growing season of vegetation. It is not yet clear how the Paris Agreement's long-term temperature goals will affect the thermal growing season of vegetation, particularly crops, in China. Based on the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) datasets and the Global Gridded Crop Model Intercomparison (GGCMI) phase 1 dataset, we have investigated changes in spatiotemporal patterns of four thermal growing season indices (Growing Degree Days, GDD; Length of Growing Season, GSL; the Start of Growing Season, GSS; the End of Growing Season, GSE) over China under global warming scenarios of 1.5 °C and 2.0 °C with four representative concentration pathway (RCP) scenarios. Our results indicate that during the periods which achieve the global warming of 1.5 °C and 2.0 °C, only 3.82% and 29.15% of the total areas in China have higher warming levels beyond the global warming targets. For warmer RCP scenarios (except RCP2.6), there was a rising trend for GSE, GDD and GSL and a decreasing trend for GSS in China. Many crop regions in China have also shown an advance of GSS, an extension of GSL and an earlier end of GSE under the global warming of 1.5 °C and 2.0 °C, suggesting that crop planting and harvesting dates need to be adjusted accordingly in order to capture appropriate timing for crop maturity and to achieve a maximum yield.
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| 5. |
- Sun, Huaiwei, et al.
(författare)
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Assessment of long-term water stress for ecosystems across China using the maximum entropy production theory-based evapotranspiration product
- 2022
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526. ; 349
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Tidskriftsartikel (refereegranskat)abstract
- Water demand growth coupled with its high spatial-temporal mismatch of water resources will lead to an increasing water scarcity worldwide. In order to investigate a robust long-term water stress for ecosystems and regions across China, the improved maximum entropy production (MEP) method was utilized to obtain a reliable evapotranspiration (ET) product during 1982–2015. Afterwards four water stress indices were constructed based on the MEP, Penman, Priestley-Taylor and complementary relationship model. The MEP estimated ET showed a close agreement with measurements at eddy covariance sites, with R2 = 0.89 and RMSE ranged from 5 to 12 mm/month. All ecosystems were indicated to suffer from a high risk of water stress, and were ranked by desert (0.67–0.93), grassland (0.60–0.78), settlement (0.49–0.63), farmland (0.48–0.63), and forest ecosystem (0.45–0.58) with four indices. Patterns of water stress at the provincial levels were revealed. Provinces including Xinjiang, Qinghai, Inner Mongolia, and Gansu in the northern regions displayed the highest water stress, and months from December to February were most vulnerable to extreme water stress. Overall, results revealed that the MEP model-based water stress index can well characterize the water stress footprints for all ecosystems and regions in China. This study can support the policy-making for improving water use efficiency and optimizing water resource management to alleviate water stress on large scales.
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| 6. |
- Sun, Huaiwei, et al.
(författare)
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Drivers of the water use efficiency changes in China during 1982–2015
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 799
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the drivers of water use efficiency (WUE), a key metric of water resources management, and its changes over eight regions across China from 1982 to 2015 based on gross primary production (GPP) and actual evapotranspiration (AET) datasets. The order of seasonal change of WUE from large to small is autumn, summer, spring and winter. The drivers include seven variables, air temperature, specific humidity, precipitation, short-wave radiation, Normalized Difference Vegetation Index (NDVI), soil moisture and CO2. Our analysis suggests that the sensitivity of annual average NDVI to WUE changes was high nationwide, but there were some differences in seasonal scales. The annual average contribution of air temperature and CO2 affecting WUE change was relatively high in China's largest area (SW, SE, E, NP). Other influencing factors were only relatively high in the local area. Seasonally, NDVI is the driving factor with the highest contribution rate in summer and autumn for NC and NW region. The seasonal contribution rates of driving factors in other regions are significantly different. For the study period (1982–2015), the shrubland ecosystem had the highest annual WUE followed by forest and cropland. The WUE of the farmland ecosystem was higher than that of the grassland ecosystem in most areas.
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| 7. |
- Sun, Huaiwei, et al.
(författare)
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Revisiting the role of transpiration in the variation of ecosystem water use efficiency in China
- 2023
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Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 0168-1923. ; 332
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Tidskriftsartikel (refereegranskat)abstract
- Efforts to develop effective climate strategies necessitate a better understanding of the relationship between terrestrial water and carbon cycles. Water use efficiency (WUE) has been often used to characterize this relationship, while the role of transpiration (T) in the variation of ecosystem WUE has been less investigated. Here, we partitioned WUEET (the ratio of gross primary productivity (GPP) to evapotranspiration (ET)) into a two-component process, i.e., the ratio of gross primary productivity to plant transpiration, GPP/T, that is WUET, and the ratio of plant transpiration to evapotranspiration, T/ET. Based on two GPP datasets (i.e., GPP based on the light use efficiency model or the vegetation index- NIRv) and the GLEAM ET dataset, this study investigated the role of T in the variation of WUE in the ecosystem level and how the role is affected by drought. We found that drought can lead to the change of ET partitioning, thus affecting the variability of WUE. The variability of WUEET was dominated by WUET. In general, the proportion of T increased gradually from humid to arid areas. To adapt to drought conditions, vegetation in arid areas tend to have a high stress resistance by increasing their WUE. We further found that WUET has stronger seasonal stability than WUEET. GPP dominated WUEET variability in humid/sub humid areas, while ET and GPP jointly dominated WUEET variability in semi-arid/arid areas. GPP dataset based on light use efficiency (LUE) could better reflect the impact of drought on vegetation. This study contributes to a better understanding of the change mechanism of ecosystem WUE and emphasizes the critical role of physiological process components in water-carbon cycling.
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| 8. |
- Sun, Huaiwei, et al.
(författare)
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The altered drivers of evapotranspiration trends around the recent warming hiatus in China
- 2022
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418 .- 1097-0088. ; 42:16, s. 8405-8422
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on the trends and the causes of variation in actual evapotranspiration (AET) around the warming hiatus over China by a comprehensive analysis applying various temporal–spatial methods. It is observed that the annual AET showed a different trend around 2000 for China as a whole. By employing segmented regression analysis for detecting warming hiatus points, high temporal inconsistency can be found in eight climatic regions of China. The impacts of meteorological variables on AET were further identified by affecting the intensity and relative change of meteorological factors. AET was highly correlated (p <.01) with solar radiation in the southeast (R = 0.80) and air specific humidity in the northwest areas (R = 0.83). AET changes presented the highest sensitivity to specific humidity in Northwest before 2006 and in north central China after 2003, with sensitivity coefficients of 1.48 and 1.74, respectively. Three variables, including air specific humidity (with an average contribution rate of ~17% in the northwest), short-wave radiation and air temperature, can be the main factors that lead to the changes in AET. The specific meteorological factors varied from region to region: the changes in AET can be ascribed to the increased wind and short-wave radiation in north central China and east China, the decreased air temperature in Tibetan Plateau, the increased specific humidity in southeast China during warming hiatus, and so on. After the warming hiatus occurred, the dominant factor of AET trends changed from air specific humidity to short-wave radiation and other factors. Generally, air specific humidity and air temperature have played leading roles in AET trends during the past 30 years.
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| 9. |
- Yan, Dong, et al.
(författare)
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Allocation of ecological water rights considering ecological networks in arid watersheds : A framework and case study of Tarim River basin
- 2022
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Ingår i: Agricultural Water Management. - : Elsevier BV. - 0378-3774. ; 267
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Tidskriftsartikel (refereegranskat)abstract
- A robust water supply system is significant to the local ecosystem of riparian vegetation in the arid basin. Considering the elasticity and relative importance of ecological water use in different regions of the basin, this study defines the ecological water rights on a multi-year scale, divides the priority of those rights based on the ecological network, and proposes a rights allocation method. The application of the method to the mainstream watershed of Tarim River in China shows that when the overall available ecological water is only 77% of the ecological water demand, it can ensure that the ecological water demand of vegetation in important areas is fully met and the growth condition is good. However, the demand in non-important areas must be less than 50% and the growth condition will deteriorate. This method expands the existing definition and distribution of water rights, and the approach of coupling ecological networks can be used for the efficient management of ecological water supply in other arid basins.
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| 10. |
- Yang, Yong, et al.
(författare)
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An R package of maximum entropy production model to estimate 41 years of global evapotranspiration
- 2022
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694. ; 614
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Tidskriftsartikel (refereegranskat)abstract
- An accurate estimation of evapotranspiration (ET) is vital for understanding the global hydrological cycle. However, large uncertainties in the present global ET products originate from the distinct model structures, assumptions, and inputs. The maximum entropy production (MEP) model provides a novel method for modeling ET based on parsimonious inputs and energy conservation. In this study, an R package for MEP (RMEP) was presented to facilitate MEP model implementation. Based on RMEP, a global ET analysis was conducted using inputs from the Global Land Data Assimilation System (GLDAS) and Global Land Surface Satellite (GLASS) products during 1978–2018, and the Mann-Kendall and Theil–Sen's methods were employed to detect the ET trends. The MEP-estimated average annual global land ET was 517 mm yr−1 during 1978–2018, and showed a close agreement with eddy-covariance (EC) measurements from 475 flux sites, with a correlation coefficient of 0.74 and root-mean-square error of 26.99 mm mon−1. The overall performance of MEP was evaluated across various land covers, and a higher ET accuracy was revealed for forestlands, wetlands, and cropland land covers. The MEP-derived ET trend corresponded well with the EC-observed ET trend, and the results indicated that the global land ET declined continuously during 1999–2018. Overall, the MEP model provided an accurate ET estimate with parsimonious inputs, which outperformed the GLDAS-Noah ET product and can serve as a global analytical method for the hydrological cycle and climate change.
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