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Understanding of the spatial connections in rainfall is a challenging and essential groundwork for reliable modeling of catchment processes. Recent developments in network theory offer new avenues to understand of the spatial variability of rainfall. The Yellow River Basin (YRB) in China is spatially extensive, with pronounced environmental gradients driven primarily by precipitation and air temperature on broad scales. Therefore, it is an ideal region to examine the availability of network theory. The concepts of clustering coefficient, degree distribution and small-world network are employed to investigate the spatial connections and architecture of precipitation networks in the YRB. The results show that (1) the choice of methods has little effect on the precipitation networks, but correlation thresholds significantly affected vertex degree and clustering coefficient values of precipitation networks; (2) the spatial distribution of the clustering coefficient appears to be high–low–high from southeast to northwest and the vertex degree is the opposite; (3) the precipitation network has small-world properties in the appropriate threshold range. The findings of this paper could help researchers to understand the spatial rainfall connections of the YRB and, therefore, become a foundation for developing a hydrological model in further studies.
Yiran Xu; Fan Lu; Kui Zhu; Xinyi Song; Yanyu Dai. Exploring the Clustering Property and Network Structure of a Large-Scale Basin’s Precipitation Network: A Complex Network Approach. Water 2020, 12, 1739 .
AMA StyleYiran Xu, Fan Lu, Kui Zhu, Xinyi Song, Yanyu Dai. Exploring the Clustering Property and Network Structure of a Large-Scale Basin’s Precipitation Network: A Complex Network Approach. Water. 2020; 12 (6):1739.
Chicago/Turabian StyleYiran Xu; Fan Lu; Kui Zhu; Xinyi Song; Yanyu Dai. 2020. "Exploring the Clustering Property and Network Structure of a Large-Scale Basin’s Precipitation Network: A Complex Network Approach." Water 12, no. 6: 1739.
Reference evapotranspiration (ET0) is an important factor for agricultural activity and water management. ET0 estimation methods have significant regional differences. The Penman–Monteith (P–M) method, which is recommended by the Food and Agriculture Organization (FAO), has been widely accepted, but it requires a large amount of data. In this study, we analysed the performance of 12 ET0 estimation methods in different sub‐regions and periods by comparing them with the FAO P–M method. North eastern China was divided into eight sub‐regions by terrains and climates. Meteorological data obtained from 126 stations between the 1950s and 2014 were used to calculate the ET0 values. The performances were identified via four indices, namely, root mean squared error, mean absolute error, average ratio and Spearman’s correlation coefficient. The optimal method for agricultural areas was then modified by using linear regression analysis. Results are demonstrated as follows: Valiantzas2, Romanenko2 and H–Makkink methods are recommended as alternative methods during the crop growing period, whereas Turc and Hargreaves–Samani methods can generate significant biases. Valiantzas2 and H–Makkink methods are the optimal methods for estimating ET0 in agricultural areas. Based on the outputs from FAO P–M method, ET0 values are most sensitive to temperature, accounting for 59.5%. Other methods that can provide similar results can be considered as alternatives. Finally, the modified equation can provide the most accurate results, but drought events also affect the accuracy of the modified method. This article is protected by copyright. All rights reserved.
Xinyi Song; Fan Lu; Weihua Xiao; Kui Zhu; Yuyan Zhou; Zibo Xie. Performance of 12 reference evapotranspiration estimation methods compared with the Penman-Monteith method and the potential influences in northeast China. Meteorological Applications 2018, 26, 83 -96.
AMA StyleXinyi Song, Fan Lu, Weihua Xiao, Kui Zhu, Yuyan Zhou, Zibo Xie. Performance of 12 reference evapotranspiration estimation methods compared with the Penman-Monteith method and the potential influences in northeast China. Meteorological Applications. 2018; 26 (1):83-96.
Chicago/Turabian StyleXinyi Song; Fan Lu; Weihua Xiao; Kui Zhu; Yuyan Zhou; Zibo Xie. 2018. "Performance of 12 reference evapotranspiration estimation methods compared with the Penman-Monteith method and the potential influences in northeast China." Meteorological Applications 26, no. 1: 83-96.
The intense climate changes and human activities have a great impact on the variation of the runoff of the coastal area of South China. In this work, the Soil and Water Assessment Tool (SWAT) is used to quantify the impact of land use and climate change of the Nanliujiang catchment on the runoff by setting 4 scenarios of land-use and climate change. The results show the runoff of the simulated and measured values had a similar trend. The value of relevant coefficient is above 0.8, and the value of Nash-Sutcliffe efficiency coefficient is about 0.8, which indicate that the SWAT model is fit for the study area. The annual average runoff depth during the period from 1995 to 2013 has increased by 53.5mm, of which the land use change resulted in 13.0mm increase on the annual average runoff depth while the climate change resulted in 40.9mm increase on the annual average runoff depth, therefore, the climate change has greater effect then the land use change. This work will delineate some helpful information for the water resources management as well as ecological protection in the coastal area of South China.
Mingzhi Yang; Weihua Xiao; Yong Zhao; Ya Huang; Baoqi Li; Dachuan Jiang; Fan Lu; Baodeng Hou. Impact of changes in land use and climate on the Runoff in the coastal areas of South China—A case study of the Nanliujiang catchment. MATEC Web of Conferences 2018, 246, 02001 .
AMA StyleMingzhi Yang, Weihua Xiao, Yong Zhao, Ya Huang, Baoqi Li, Dachuan Jiang, Fan Lu, Baodeng Hou. Impact of changes in land use and climate on the Runoff in the coastal areas of South China—A case study of the Nanliujiang catchment. MATEC Web of Conferences. 2018; 246 ():02001.
Chicago/Turabian StyleMingzhi Yang; Weihua Xiao; Yong Zhao; Ya Huang; Baoqi Li; Dachuan Jiang; Fan Lu; Baodeng Hou. 2018. "Impact of changes in land use and climate on the Runoff in the coastal areas of South China—A case study of the Nanliujiang catchment." MATEC Web of Conferences 246, no. : 02001.
Based on the Penman-Monteith formula recommended by the World Food and Agriculture Organization (FAO) and the Mann-Kendall trend test method, the variation trend of potential evapotranspiration in the Yellow River Basin from 1952 to 2014 is analyzed. The results showed that the potential evapotranspiration of 43.3% of the 90 meteorological stations in the Yellow River Basin showed a significant upward trend. 30% of the stations showed a significant downward trend, and 26.7% of the stations had no obvious trend of change. In all the secondary areas of water resources, the stations above Longyangxia are basically marked upward. The Longyangxia to the northern part of Lanzhou, the Longmen to the east of Sanmenxia and the Sanmenxia to Huayuankou are all significant descending sites. The change trend of the sites below the Huayuankou is not obvious. In other partition three kinds of sites are distributed. Through the correlation analysis, it is found that the increase of temperature has a great influence on the stations where the potential evapotranspiration is significantly increased, and the decrease of wind speed is the main reason for the significant decrease of potential evapotranspiration in some stations.
Yanyu Dai; Fan Lu; Kui Zhu; Xinyi Song; Yiran Xu. The Trend and Influencing Factors of Potential Evapotranspiration in the Yellow River. MATEC Web of Conferences 2018, 246, 01020 .
AMA StyleYanyu Dai, Fan Lu, Kui Zhu, Xinyi Song, Yiran Xu. The Trend and Influencing Factors of Potential Evapotranspiration in the Yellow River. MATEC Web of Conferences. 2018; 246 ():01020.
Chicago/Turabian StyleYanyu Dai; Fan Lu; Kui Zhu; Xinyi Song; Yiran Xu. 2018. "The Trend and Influencing Factors of Potential Evapotranspiration in the Yellow River." MATEC Web of Conferences 246, no. : 01020.
The climate change and human activities can principally doubt the frequency analysis methods which assume that the hydrological events are stationary. The Pearson type 3 (P3) distribution, which has been widely applied in frequency analysis under the stationary condition, was developed for the nonstationary cases. The distribution parameters can be expressed as exponential or polynomial functions with time or other covariates. Parameter estimation for the nonstationary P3 model was done with the penalized maximum likelihood estimation (PMLE) method in which we applied a restrictive penalty on the location parameter to avoid unreasonable results. The results of the nonstationary P3 model were compared to that of the generalized extreme value (GEV) distribution, in which the generalized maximum likelihood estimation (GMLE) method was applied to estimate the parameters. The Monte Carlo simulations indicated that the nonstationary P3 model provided better results than the nonstationary GEV model for different sample sizes. Both models were also applied in hydrological series with various trends and record lengths to prove the feasibility of the nonstationary P3 model in practical applications. The applications showed that the nonstationary P3 model performed better than the nonstationary GEV model in most of the studied cases.
Xinyi Song; Fan Lu; Hao Wang; Weihua Xiao; Kui Zhu; Song Xinyi; Lu Fan; Wang Hao; Xiao Weihua; Zhu Kui. Penalized maximum likelihood estimators for the nonstationary Pearson type 3 distribution. Journal of Hydrology 2018, 567, 579 -589.
AMA StyleXinyi Song, Fan Lu, Hao Wang, Weihua Xiao, Kui Zhu, Song Xinyi, Lu Fan, Wang Hao, Xiao Weihua, Zhu Kui. Penalized maximum likelihood estimators for the nonstationary Pearson type 3 distribution. Journal of Hydrology. 2018; 567 ():579-589.
Chicago/Turabian StyleXinyi Song; Fan Lu; Hao Wang; Weihua Xiao; Kui Zhu; Song Xinyi; Lu Fan; Wang Hao; Xiao Weihua; Zhu Kui. 2018. "Penalized maximum likelihood estimators for the nonstationary Pearson type 3 distribution." Journal of Hydrology 567, no. : 579-589.
Green water accounts for two-thirds of precipitation, and the proportion could be even higher in dry years. Conflicts between water supply and demand have gradually become severe in the Hai River Basin (HRB) due to the socio-economic development. Thus, the exploitation and the utilization of green water have attracted increasing attention. By gathering the related hydrological, meteorological, and geographic data, the spatiotemporal distribution of green water in HRB and the impacts of land use types on green water are analyzed based on the SWAT (Soil and Water Assessment Tool) model in this study. Furthermore, three new indices are proposed for evaluation, including the maximum possible storage of green water (MSGW), the consumed green water (CGW), and the utilizable green water (UGW). The results show that (1) the MSGW is relatively low in plain areas and its spatial distribution is significantly associated with the soil type; (2) according to the evaluation results of CGW and UGW in HRB, a further improvement of utilization efficiency of green water could be achieved; (3) in general, the utilization efficiency of precipitation in farmlands is higher than other land use types, which means that the planting of appropriate plants could be helpful to enhance the utilization efficiency of green water. Our results summarize the spatiotemporal distribution of green water resource and provide a reference for water resources management in other water-short agricultural areas.
Kui Zhu; Zibo Xie; Yong Zhao; Fan Lu; Xinyi Song; Lu Li; Xiaomeng Song. The Assessment of Green Water Based on the SWAT Model: A Case Study in the Hai River Basin, China. Water 2018, 10, 798 .
AMA StyleKui Zhu, Zibo Xie, Yong Zhao, Fan Lu, Xinyi Song, Lu Li, Xiaomeng Song. The Assessment of Green Water Based on the SWAT Model: A Case Study in the Hai River Basin, China. Water. 2018; 10 (6):798.
Chicago/Turabian StyleKui Zhu; Zibo Xie; Yong Zhao; Fan Lu; Xinyi Song; Lu Li; Xiaomeng Song. 2018. "The Assessment of Green Water Based on the SWAT Model: A Case Study in the Hai River Basin, China." Water 10, no. 6: 798.
The Nanliujiang catchment is one of major rice production bases of South China. Irrigation districts play an important role in rice production which requires a large quantity of water. There are potential risks on future climate change in response to rice production, agricultural irrigation water use and pollution control locally. The SWAT model was used to quantify the yield and water footprint (WF) of rice in this catchment. A combined method of automatic and manual sub-basin delineation was used for the model setup in this work to reflect the differences between irrigation districts in yield and water use of rice. We validated our simulations against observed leaf area index, biomass and yield of rice, evapotranspiration and runoff. The outputs of three GCMs (GFDL-ESM2M, IPSL-CM5A-LR and HadGEM2-ES) under three RCPs (RCP2.6, 4.5, 8.5) were fed to the SWAT model. The results showed that: (a) the SWAT model is an ideal tool to simulate rice development as well as hydrology; (b) there would be increases in rice yield ranged from +1.4 to +10.6% under climate projections of GFDL-ESM2M and IPSL-CM5A-LR but slight decreases ranged from −3.5 to −0.8% under that of HadGEM2-ES; (c) the yield and WFs of rice displayed clear differences in the catchment, with a characteristic that high in the south and low in the north, mainly due to the differences in climatic conditions, soil quality and fertilization amount; (d) there would be a decrease by 45.5% in blue WF with an increase by 88.1% in green WF, which could provide favorable conditions to enlarge irrigated areas and take technical measures for improving green water use efficiency of irrigation districts; (e) a clear rise in future grey WF would present enormous challenges for the protection of water resources and environmental pollution control in this catchment. So it should be to improved nutrient management strategies for the agricultural non-point source pollution control in irrigation districts, especially for the Hongchaojiang and Hepu irrigation districts.
Mingzhi Yang; Weihua Xiao; Yong Zhao; Xudong Li; Ya Huang; Fan Lu; Baodeng Hou; Baoqi Li. Assessment of Potential Climate Change Effects on the Rice Yield and Water Footprint in the Nanliujiang Catchment, China. Sustainability 2018, 10, 242 .
AMA StyleMingzhi Yang, Weihua Xiao, Yong Zhao, Xudong Li, Ya Huang, Fan Lu, Baodeng Hou, Baoqi Li. Assessment of Potential Climate Change Effects on the Rice Yield and Water Footprint in the Nanliujiang Catchment, China. Sustainability. 2018; 10 (2):242.
Chicago/Turabian StyleMingzhi Yang; Weihua Xiao; Yong Zhao; Xudong Li; Ya Huang; Fan Lu; Baodeng Hou; Baoqi Li. 2018. "Assessment of Potential Climate Change Effects on the Rice Yield and Water Footprint in the Nanliujiang Catchment, China." Sustainability 10, no. 2: 242.
In the current human-influenced era, drought is initiated by natural and human drivers, and human activities are as integral to drought as meteorological factors. In large irrigated agricultural regions with high levels of human intervention, where the natural farmland soil moisture has usually been changed significantly by high-frequency irrigation, the actual severity of agricultural drought is distorted in traditional drought indices. In this work, an agricultural drought index that considering irrigation processes based on the Palmer drought severity index (IrrPDSI) was developed to interpret the real agricultural drought conditions in irrigated regions, with a case study in the Haihe River Basin in northeast China. The water balance model in the original PDSI was revised by an auto-irrigation threshold method combined with a local irrigation schedule. The auto-irrigation setting of the index was used by taking irrigation quotas during specific growth stages of specific crops (wheat–corn) into consideration. A series of weekly comparative analyses are as follows: (1) The soil moisture analyses showed that soil moisture values calculated by the modified water balance model were close to the real values; (2) The statistical analyses indicated that most of the stations in the study area based on IrrPDSI had nearly normal distributed values; (3) The time series and spatial analyses showed that the results of the IrrPDSI-reported dry-wet evaluation were more consistent with documented real conditions. All the results revealed that IrrPDSI performed well when used to assess agricultural drought. This work has direct significance for agricultural drought management in large irrigated areas heavily disturbed by human activity.
Mingzhi Yang; Weihua Xiao; Yong Zhao; Xudong Li; Fan Lu; Chuiyu Lu; Yan Chen. Assessing Agricultural Drought in the Anthropocene: A Modified Palmer Drought Severity Index. Water 2017, 9, 725 .
AMA StyleMingzhi Yang, Weihua Xiao, Yong Zhao, Xudong Li, Fan Lu, Chuiyu Lu, Yan Chen. Assessing Agricultural Drought in the Anthropocene: A Modified Palmer Drought Severity Index. Water. 2017; 9 (10):725.
Chicago/Turabian StyleMingzhi Yang; Weihua Xiao; Yong Zhao; Xudong Li; Fan Lu; Chuiyu Lu; Yan Chen. 2017. "Assessing Agricultural Drought in the Anthropocene: A Modified Palmer Drought Severity Index." Water 9, no. 10: 725.
It is essential to understand the changing patterns in reference evapotranspiration (ET0) and its relation to climate variables. In this study, meteorological data obtained from the Sanjiang Plain (SJP) between 1959 and 2013 are used to calculate ET0 via the Penman–Monteith method. This study analyses the spatial and temporal changes of ET0 and determines which meteorological variables have an impact on this. The Mann–Kendall test, moving t-test, sensitivity analysis and simulated results have been used to conduct these analyses. The results demonstrate the following. (1) Spatially, there is an increasing trend in the annual ET0 values in agricultural areas. However, significant decreasing trends (P < 0.05) can be found in mountainous regions. (2) Temporally, two abrupt changes can be detected in the early 1980s and the late 1990s for the entire SJP, leading to large inter-annual differences. (3) Sensitivity analysis shows that relative humidity (RH) is the most sensitive climate variable and has a negative influence on ET0, followed by temperature, sunshine duration and wind speed, all of which exert positive impacts. (4) The simulated result shows that ET0 is most sensitive to RH. However, significant reductions in wind speed can exert large influences on the ET0 values.
Xinyi Song; Kui Zhu; Fan Lu; Weihua Xiao. Spatial and temporal variation of reference evapotranspiration under climate change: a case study in the Sanjiang Plain, Northeast China. Water Policy 2017, 49, 251 -265.
AMA StyleXinyi Song, Kui Zhu, Fan Lu, Weihua Xiao. Spatial and temporal variation of reference evapotranspiration under climate change: a case study in the Sanjiang Plain, Northeast China. Water Policy. 2017; 49 (1):251-265.
Chicago/Turabian StyleXinyi Song; Kui Zhu; Fan Lu; Weihua Xiao. 2017. "Spatial and temporal variation of reference evapotranspiration under climate change: a case study in the Sanjiang Plain, Northeast China." Water Policy 49, no. 1: 251-265.
Profile likelihood function is introduced to analyze the uncertainty of hydrometeorological extreme inference and the theory of estimating confidence intervals of the key parameters and quantiles of extreme value distribution by profile likelihood function is described. GEV (generalized extreme value) distribution and GP (generalized Pareto) distribution are used respectively to fit the annual maximum daily flood discharge sample of the Yichang station in the Yangtze River and the daily rainfall sample in 10 big cities including Guangzhou. The parameters of the models are estimated by maximum likelihood method and the fitting results are tested by probability plot, quantile plot, return level plot and density plot. The return levels and confidence intervals of flood and rainstorm in different return periods are calculated by profile likelihood function. The results show that the asymmetry of the profile likelihood function curve increases with the return period, which can reflect the effect of the length of sample series and return periods on confidence interval. As an effective tool for estimating confidence interval of the key parameters and quantiles of extreme value distribution, profile likelihood function can lead to a more accurate result and help to analyze the uncertainty of extreme values of hydrometeorology.
Fan Lu; Hao Wang; Denghua Yan; Dongdong Zhang; Weihua Xiao. Application of profile likelihood function to the uncertainty analysis of hydrometeorological extreme inference. Science China Technological Sciences 2013, 56, 3151 -3160.
AMA StyleFan Lu, Hao Wang, Denghua Yan, Dongdong Zhang, Weihua Xiao. Application of profile likelihood function to the uncertainty analysis of hydrometeorological extreme inference. Science China Technological Sciences. 2013; 56 (12):3151-3160.
Chicago/Turabian StyleFan Lu; Hao Wang; Denghua Yan; Dongdong Zhang; Weihua Xiao. 2013. "Application of profile likelihood function to the uncertainty analysis of hydrometeorological extreme inference." Science China Technological Sciences 56, no. 12: 3151-3160.
The novel title complex, {[Cu(3)(C(8)H(3)NO(6))(2)(OH)(2)(H(2)O)(6)].2H(2)O}(n), has a one-dimensional polymeric double chain structure where the three Cu atoms are linked by mu(2)-OH and mu(2)-H(2)O groups, and these trinuclear centres are bridged by two 3-nitrophthalate ligands. The asymmetric unit contains one and a half crystallographically independent Cu atoms (one lying on a centre of inversion), both coordinated by six O atoms and exhibiting distorted octahedral coordination geometries, but with different coordination environments. Each 3-nitrophthalate ligand connects to three Cu atoms through two O atoms of one carboxylate group and one O atom of the nitro group. The remaining carboxylate group is free and is involved in intrachain hydrogen bonds, reinforcing the chain linkage.
Feng-Qin Wang; Fan-Li Lu; Bin Wei; Yong-Nan Zhao. Poly[[di-?-aqua-tetraaquadi-?-hydroxido-bis(? 3 -3-nitrophthalato)tricopper(II)] dihydrate]. Acta Crystallographica Section C Crystal Structure Communications 2008, 65, 1 .
AMA StyleFeng-Qin Wang, Fan-Li Lu, Bin Wei, Yong-Nan Zhao. Poly[[di-?-aqua-tetraaquadi-?-hydroxido-bis(? 3 -3-nitrophthalato)tricopper(II)] dihydrate]. Acta Crystallographica Section C Crystal Structure Communications. 2008; 65 (1):1.
Chicago/Turabian StyleFeng-Qin Wang; Fan-Li Lu; Bin Wei; Yong-Nan Zhao. 2008. "Poly[[di-?-aqua-tetraaquadi-?-hydroxido-bis(? 3 -3-nitrophthalato)tricopper(II)] dihydrate]." Acta Crystallographica Section C Crystal Structure Communications 65, no. 1: 1.