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1.
Groundwater provides an important source of water for maize cultivation where the water table is shallow in the semi-arid Hailiutu River catchment of the Maowusu Desert on the Erdos Plateau in Northwest China. A HYDRUS-1D model of the unsaturated flow beneath a maize (Zea mays L.) field was calibrated and validated with measured soil water contents at various depths during the maize growing period from 30 April to 1 October 2011, and from 23 May to 27 September 2012, respectively. The model computed the actual maize evapotranspiration (ETa) as 580 mm during the whole growing period from 30 April to 1 October 2011. The groundwater contribution to ETa was calculated to be 220 mm, accounting for 38% of maize water use during the growing season in 2011. When the groundwater level drops below a depth of 157 cm, maize can no longer use groundwater for transpiration. The irrigation water requirement increases with the increase of groundwater table depth. These results are very important for managing crop irrigation in the area.
EDITOR D. KoutsoyiannisASSOCIATE EDITOR L. Ruiz 相似文献
2.
Sensitivity of the Penman-Monteith reference evapotranspiration to sunshine duration in the Upper Mekong River Basin 总被引：1，自引：1，他引：0
Sensitivity analysis is important in understanding the relationship between sunshine duration (SD) and reference evapotranspiration (ETref). This study was developed in the Lancang-Mekong River Basin using a non-dimensional relative sensitivity coefficient (SN) relating ETref to SD. The SN for January and July for each station were calculated. The results indicate that (a) the SD and SN change in similar ways, where January and July are selected as two representative time slices; (b) the spatial distributions of the long-term averaged SN for January and July are the reverse of each other; (c) the most abrupt changes in climate occur in the 1980s and the middle region is sensitive to climate change; and (d) periodicities of 2–4 and 14–16 years are detected in the basin generally. The significant increase of inter-decadal filter variance indicates changes in the long-term memory of the local climate system.
EDITOR Z.W. KundzewiczASSOCIATE EDITOR not assigned 相似文献
3.
基于CMIP5模式鄱阳湖流域未来参考作物蒸散量预估 总被引：3，自引：0，他引：3
预测未来气候情境下鄱阳湖流域参考作物蒸散量(Reference crop Evapotranspiration,ET0)的时空分布可为流域水资源的优化管理,为科学应对气候变化对农业生产的影响提供基础数据支撑.利用鄱阳湖流域14个气象站点1961-2014年逐日气象数据,采用Penman-Monteith公式计算出历史ET0;基于同期美国环境中心(NCEP)再分析数据及2006-2100年CMIP5中CNRM-CM5模式在RCP4. 5和RCP8. 5情景下的预测数据,经统计降尺度模型(statistical downscaling model,SDSM)模拟和偏差校正,预测流域未来ET0;通过Mann-Kendall检验、普通克里金插值和空间自相关法分析了流域1961-2100年ET0的时空演变特征.结果表明:NCEP再分析资料与流域ET0建立的逐步回归降尺度模型模拟效果较好,CNRMCM5模式降尺度模拟结果经偏差校正后,精度明显提高,适宜流域未来ET0的预估.鄱阳湖流域在基准期1961-2010年ET0整体上呈减小趋势,空间分布上呈南北高、中间低的特点,表现出明显的空间差异性.RCP4.5、RCP8.5情景下未来3个时期鄱阳湖流域ET0较基准期均呈不同程度的增加趋势,其空间分布整体表现为东高西低、局地略有突出;无论是在基准期或是未来情景下的3个时期,ET0均具有较强的空间自相关性.在RCP8.5情景下,鄱阳湖1961-2100年干旱指数呈现出较为明显的上升趋势,流域的干旱状况随时间加剧,2011-2100年间流域绝大部分地区由湿润区转为半湿润区,干旱指数自南向北递减,赣江流域将是鄱阳湖流域未来干旱风险的重点防范区. 相似文献
4.
Abstract To explore the spatial and temporal variations of the reference evapotranspiration (ETref) is helpful to understand the response of hydrological processes to climate changes. In this study, ETref was calculated by the Penman-Monteith method (P-M method) using air temperature, wind speed, relative humidity and sunshine hours at 89 meteorological stations during 1961–2006 in the Yellow River Basin (YRB), China. The spatial distribution and temporal variations of ETref were explored by means of the kriging method, the Mann-Kendall (M-K) method and the linear regression model, and the causes for the variations discussed. The contribution of main meteorological variables to the variations of ETref was explored. From the results we found that: (1) the spatial distributions of ETref display seasonal variation, with similar spatial patterns in spring, summer and autumn; (2) temporal trends for ETref showed large variation in the upper, middle and lower regions of the basin, most of the significant trends (P?=?0.05) were detected in the middle and lower regions, and, in particular, the upward and downward trends were mainly detected in the middle region and lower region of the basin, respectively; and (3) sensitivity analysis identified the most sensitive variable for ETref as relative humidity, followed by air temperature, sunshine hours and wind speed at the basin scale. Citation Yang, Zhifeng, Liu, Qiang & Cui, Baoshan (2011) Spatial distribution and temporal variation of reference evapotranspiration during 1961–2006 in the Yellow River Basin, China. Hydrol. Sci. J. 56(6), 1015–1026. 相似文献
5.
Changes in potential evapotranspiration and surface runoff in 1981–2010 and the driving factors in Upper Heihe River Basin in Northwest China 
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下载免费PDF全文 Changes in potential evapotranspiration and surface runoff can have profound implications for hydrological processes in arid and semiarid regions. In this study, we investigated the response of hydrological processes to climate change in Upper Heihe River Basin in Northwest China for the period from 1981 to 2010. We used agronomic, climatic and hydrological data to drive the Soil and Water Assessment Tool model for changes in potential evapotranspiration (ET0) and surface runoff and the driving factors in the study area. The results showed that increasing autumn temperature increased snow melt, resulting in increased surface runoff, especially in September and October. The spatial distribution of annual runoff was different from that of seasonal runoff, with the highest runoff in Yeniugou River, followed by Babaohe River and then the tributaries in the northern of the basin. There was no evaporation paradox at annual and seasonal time scales, and annual ET0 was driven mainly by wind speed. ET0 was driven by relative humidity in spring, sunshine hour duration in autumn and both sunshine hour duration and relative humility in summer. Surface runoff was controlled by temperature in spring and winter and by precipitation in summer (flood season). Although surface runoff increased in autumn with increasing temperature, it depended on rainfall in September and on temperature in October and November. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
6.
Projection of surface water resources in the context of climate change in typical regions of China 总被引：1，自引：1，他引：0
Climate change and its impact on hydrological processes are overarching issues that have brought challenges for sustainable water resources management. In this study, surface water resources in typical regions of China are projected in the context of climate change. A water balance model based on the Fu rational function equation is established to quantify future natural runoff. The model is calibrated using data from 13 hydrological stations in 10 first-class water resources zones of China. The future precipitation and temperature series come from the ISI-MIP (Inter-Sectoral Impact Model Intercomparison Project) climate dataset. Taking natural runoff for 1961–1990 as a baseline, the impacts of climate change on natural runoff are studied under three emissions scenarios: RCP2.6, RCP4.5 and RCP8.5. Simulated results indicate that the arid and semi-arid region in the northern part of China is more sensitive to climate change compared to the humid and semi-humid region in the south. In the near future (2011–2050), surface water resources will decrease in most parts of China (except for the Liaozhong and Daojieba catchments), especially in the Haihe River Basin and the middle reaches of the Yangtze River Basin. The decrement of surface water resources in the northern part of China is more than that in the southern part. For the periods 2011–2030 and 2031–2050, surface water resources are expected to decrease by 12–13% in the northern part of China, while those in the southern part will decrease by 7–10%.
EDITOR D. KoutsoyiannisASSOCIATE EDITOR R. Hirsch 相似文献
7.
ABSTRACTThe Hargreaves method provides reference evapotranspiration (ETo) estimates when only air temperature data are available, although it requires previous local calibration for an acceptable performance. This method was evaluated using the data from 71 meteorological stations in the Seolma-cheon basin (8.48 km2), South Korea, comparing daily estimates against those from the Penman‐Monteith (PM) method, which was used as the standard. To estimate reference ETo more exactly, considering the climatological characteristics in South Korea, parameter regionalization of the Hargreaves equation is carried out. First, the modified Hargreaves equation is presented after an analysis of the relationship between solar radiation and temperature. Second, parameter (KET) optimization of the regional calibration of the Hargreaves equation (RCH) is performed using the PM method and the modified equation at 71 meteorological stations. Next, an application was carried out to evaluate the evapotranspiration methods (PM, original Hargreaves and RCH) in the SWAT (Soil and Water Assessment Tool) model by comparing these with the measured actual evapotranspiration (AET) in the basin. The SWAT model was calibrated using 3 years (2007–2009) of daily streamflow at the watershed outlet and 3 years (2007–2009) of daily AET measured at a mixed forest. The model was validated with 3 years (2010‐2012) of streamflow and AET. RCH will contribute to a better understanding of evapotranspiration of an ungauged watershed in areas where meteorological information is scarce.
EDITOR D. Koutsoyiannis ASSOCIATE EDITOR Not assigned 相似文献
8.
Josepha Ivanka Wessels 《水文科学杂志》2013,58(7):1323-1337
ABSTRACTThe concept of Integrated Water Resources Management (IWRM) has enjoyed immense popularity and thus has been the preferred approach for river basin management. IWRM generally has a strong focus on rational choice, based on a technocratic conceptual interpretation of the conventional hydrological cycle. However, uncritical acceptance of IWRM runs the risk of blinding policy makers and academics for the defining impact of context, socio-cultural, political, historical and cognitive dimensions in water cooperation. Human behaviour in water cooperation was tested and observed during eight experiments with the Jordan River Basin Boardgame Exercise (JRBBE) played with respondent groups from inside and outside the Jordan River Basin. The experiments consisted of one control group outside the basin and seven respondent groups both outside and inside the basin. This article argues that the role of identities, beliefs and perception-of-the-other, should be taken more into account in order to develop successful and socio-political sustainable river basin management.
EDITOR D. Koutsoyiannis; ASSOCIATE EDITOR not assigned 相似文献
9.
ABSTRACTA semi-distributed hydrological model of the Niger River above and including the Inner Delta is developed. GCM-related uncertainty in climate change impacts are investigated using seven GCMs for a 2°C increase in global mean temperature, the hypothesised threshold of “dangerous” climate change. Declines in precipitation predominate, although some GCMs project increases for some sub-catchments, whilst PET increases for all scenarios. Inter-GCM uncertainty in projected precipitation is three to five times that of PET. With the exception of one GCM (HadGEM1), which projects a very small increase (3.9%), river inflows to the Delta decline. There is considerable uncertainty in the magnitude of these reductions, ranging from 0.8% (HadCM3) to 52.7% (IPSL). Whilst flood extent for HadGEM1 increases (mean annual peak +1405 km2/+10.2%), for other GCMs it declines. These declines range from almost negligible changes to a 7903 km2 (57.3%) reduction in the mean annual peak.
Editor Z.W. Kundzewicz; Associate editor not assigned 相似文献
10.
To predict future river flows, empirical trend projection (ETP) analyses and extends historic trends, while hydroclimatic modelling (HCM) incorporates regional downscaling from global circulation model (GCM) outputs. We applied both approaches to the extensively allocated Oldman River Basin that drains the North American Rocky Mountains and provides an international focus for water sharing. For ETP, we analysed monthly discharges from 1912 to 2008 with non‐parametric regression, and extrapolated changes to 2055. For modelling, we refined the physical models MTCLIM and SNOPAC to provide water inputs into RIVRQ (river discharge), a model that assesses the streamflow regime as involving dynamic peaks superimposed on stable baseflow. After parameterization with 1960–1989 data, we assessed climate forecasts from six GCMs: CGCM1‐A, HadCM3, NCAR‐CCM3, ECHAM4 and 5 and GCM2. Modelling reasonably reconstructed monthly hydrographs (R2 about 0·7), and averaging over three decades closely reconstructed the monthly pattern (R2 = 0·94). When applied to the GCM forecasts, the model predicted that summer flows would decline considerably, while winter and early spring flows would increase, producing a slight decline in the annual discharge (?3%, 2005–2055). The ETP predicted similarly decreased summer flows but slight change in winter flows and greater annual flow reduction (?9%). The partial convergence of the seasonal flow projections increases confidence in a composite analysis and we thus predict further declines in summer (about ? 15%) and annual flows (about ? 5%). This composite projection indicates a more modest change than had been anticipated based on earlier GCM analyses or trend projections that considered only three or four decades. For other river basins, we recommend the utilization of ETP based on the longest available streamflow records, and HCM with multiple GCMs. The degree of correspondence from these two independent approaches would provide a basis for assessing the confidence in projections for future river flows and surface water supplies. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
11.
Assessment of surface water resources and evapotranspiration in the Haihe River basin of China using SWAT model 总被引：2，自引：0，他引：2
Quantitative assessment of surface water resources (SWRs) and evapotranspiration (ET) is essential and significant for reasonably planning and managing water resources in the Haihe River basin which is facing severe water shortage. In this study, a distributed hydrological model of the Haihe River basin was constructed using the Soil and Water Assessment Tool, well considering the reservoirs and agricultural management practices for reasonable simulation. The crop parameters were independently calibrated with the observed crop data at six experimental stations. Then, sensitivity ranks of hydrological parameters were analysed, which suggested the important parameters used for calibration. The model was successfully calibrated using the monthly observed data of discharge in around 1970–1991 and actual ET (ETa) in 2002–2004 for the mountainous area and Haihe plain, respectively. Meanwhile, good agreements between the simulated and statistical crop yields in 1985–2005 further verified the model's appropriateness. Finally, the calibrated model was used to assess SWRs and ETa in time and space during 1961–2005. Results showed that the average annual natural SWRs and the ETa were about 17.5 billion cubic metre and 542 mm, respectively, both with a slight downward trend. The spatial distributions of both SWRs and ETa were significantly impacted by variations of precipitation and land use. Moreover, the reservoir in operation was the main factor for the noticeable decline of actual SWRs. In the Haihe plain, the ETa with irrigation was increased by 46% compared with that under rainfed conditions. In addition, this study identified the regions with potential to improve the irrigation effects on water use. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
12.
ABSTRACTThe impact of climate variables on monthly reference evapotranspiration (ETo) is a critical issue in water resources management and irrigation planning. The spatio-temporal contribution of climate variables to ETo in the Pearl River Basin (PRB), China, from 1960 to 2016 were calculated based on sensitivity and relative change of each climatic variable. The results show that annual ETo total decreased by 1.64% and diminished in magnitude from the southeast to the northwest. Sunshine duration, wind speed and relative humidity decreased by 15.5%, 7.4%, and 4.0%, respectively, while average temperature increased by 4.25%. The ETo showed a positive sensitivity to all variables except relative humidity, which showed a negative sensitivity. Sunshine duration had the highest contribution of ?4.26%, and the overall decrease in ETo was mainly caused by the declines in sunshine duration and wind speed, which offset the positive impact of rises in average temperature and reduction in relative humidity. 相似文献
13.
Changes in reference evapotranspiration over China during 1960–2012: Attributions and relationships with atmospheric circulation 下载免费PDF全文
下载免费PDF全文 This study investigates reference evapotranspiration (ET0) trends in China from 1960 to 2012 based on the Penman–Monteith equation and gridded meteorological measurements. Under the combined impacts of factors influencing ET0 (i.e., net radiation [RN], mean temperature [TAVE], vapour pressure deficit [VPD], and wind speed [WND]), both seasonal and annual ET0 for the whole China and more than half of the grids decreased over the past 53 years. The attribution analyses suggest that for the whole China, the WND is responsible for annual and seasonal ET0 decreases (excluding summer, where RN is responsible). Across China, the annual cause of WND with the largest spatial extent (43.1% of grids) mainly derives from north of the Changjiang River Basin (CJRB), whereas VPD (RN) as a cause is dispersedly distributed (within and to the south of the CJRB). In summer, RN is dominant in more than half of the grids, but the dominance of VPD and WND accounts for approximately 90% of grids during the remaining seasons. Finally, the correlation coefficients between ET0 and the Atlantic Oscillation (AO), North AO, Indian Ocean Dipole (IOD), Pacific Decadal Oscillation (PDO), and El Niño Southern Oscillation (ENSO) indices with different lead times are calculated. For the whole China, annual and seasonal ET0 always significantly correlate with these indices (excluding the IOD) but with varied lead times. Additionally, near half of the grids show significant and maximum (i.e., the largest one between ET0 and a certain index with a lead time of 0–3 seasons) correlation coefficients of ET0 with PDO in spring and summer, ENSO in autumn, and AO in winter. This study is not only significant for understanding ET0 changes, but it also provides preliminary and fundamental reference information for ET0 prediction. 相似文献
14.
In this study we quantify the spatial variability of seasonal water balances within the Omo-Ghibe River Basin in Ethiopia using methods proposed within the Prediction in Ungauged Basins initiative. Our analysis consists of: (1) application of the rainfall–runoff model HBV-Light to several sub-catchments for which runoff data are available, and (2) estimation of water balances in the remaining ungauged catchments through application of the model with regionalized parameters. The analyses of the resulting water balance outcomes reveal that the seasonal water balance across the Omo-Ghibe Basin is driven by precipitation regimes that change with latitude, from being strongly “seasonal” in the north to “precipitation spread throughout the year, but with a definite wetter season” in the south. The basin is divided into two distinct regions based on patterns of seasonal water balance and, in particular, seasonal patterns of soil moisture storage.
EDITOR D. KoutsoyiannisASSOCIATE EDITOR A. Efstratiadis 相似文献
15.
Groundwater systems in arid regions will be particularly sensitive to climate change owing to the strong dependence of rates of evapotranspiration on temperature, and shifts in the precipitation regimes. Irrigation use in these arid regions is typically a large component of the water budget, and may increase due to changes in soil moisture resulting from higher temperatures and changes in the timing of precipitation events. In this study, future predicted climate change scenarios from three global climate models (CGCM1 GHG+A1, CGCM3.1 A2, and HadCM3 A2) are used to determine the sensitivity of recharge to different climate models in an irrigated agricultural region. The arid Oliver region (annual precipitation 300 mm) in the Okanagan Basin, British Columbia, is used to demonstrate the approach. Irrigation return flow, as a contribution to total diffuse recharge, is simulated by calculating the daily applied irrigation based on estimates of seasonal crop water demand and the forecasted precipitation and evaporation data. The relative contribution of irrigation return flow to groundwater recharge under current and future climate conditions is modelled. Temperature data were downscaled using Statistical Downscaling Model (SDSM), while precipitation and solar radiation changes were estimated directly from the GCM data. Shifts in climate, from present to future predicted, were applied to a stochastic weather generator, and used to force a one-dimensional hydrologic model, HELP 3.80D. Results were applied spatially, according to different soil profiles, slope and vegetation, over a 22.5 km by 8.6 km region. Changes to recharge in future time periods for each GCM result in modest increases of recharge with the peak recharge shifting from March to February. Lower recharge rates and higher potential evapotranspiration rates are similarly predicted by all three models for the summer months. All scenarios show that the potential growing season will expand between 3 and 4 weeks due to increases in temperature. However, the magnitude of the change varies considerably between models. CGCM3.1 has the largest increases of recharge rates, CGCM1 has very minor increases, and HadCM3 is relatively stable (as indicated by the near-zero changes between climate states). The significant differences between these three models indicate that prediction of future recharge is highly dependent on the model selected. The minor increase of annual recharge in future predicted climate states is due the shift of peak recharge from increased temperature. Irrigation rates dominate total recharge during the summer months in this arid area. Recharge in irrigated areas is significantly higher than natural recharge, with irrigation return flow between 25% and 58%. A comparison of recharge results for the least efficient and the most efficient irrigation systems indicates that the latter are more sensitive to choice of GCM. 相似文献
16.
Abstract The Blaney-Criddle (BC) temperature-based equation is used in areas where the complete weather data to estimate reference evapotranspiration (ET0) by the Penman-Monteith FAO-56 (PMF-56) standard model is complex. In this study, the BC equation was first tested and calibrated against the ET0 values computed by the PMF-56 method using data from 17 weather stations in arid regions of Iran. Then, geographical information systems (GIS)-based spatially-distributed maps of ET0 were prepared by means of geographic/topographic factors derived from a digital elevation model (DEM) for all months, separately. The results indicate that the original BC equation overestimated PMF-56 ET0 by 4% at the study sites. The BC equation produced closer ET0 estimates to the PMF-56 method after it was calibrated. The error rate of <3% for the spatial modelling approach suggests that the developed ET0 maps are reliable. Editor D. Koutsoyiannis; Associate editor D. Yang Citation Tabari, H., Hosseinzadeh Talaee, P., and Shifteh Some'e, B., 2013. Spatial modelling of reference evapotranspiration using adjusted Blaney-Criddle equation in an arid environment. Hydrological Sciences Journal, 58 (2), 408–420. 相似文献
17.
Trend analysis of reference evapotranspiration in Northwest China: The roles of changing wind speed and surface air temperature 总被引：2，自引：0，他引：2
Reference evapotranspiration (ET0) is an important element in the water cycle that integrates atmospheric demands and surface conditions, and analysis of changes in ET0 is of great significance for understanding climate change and its impacts on hydrology. As ET0 is an integrated effect of climate variables, increases in air temperature should lead to increases in ET0. However, this effect could be offset by decreases in vapor pressure deficit, wind speed, and solar radiation which lead to the decrease in ET0. In this study, trends in the Penman–Monteith ET0 at 80 meteorological stations during 1960–2010 in the driest region of China (Northwest China) were examined. The results show that there was a change point for ET0 series around the year 1993 based on the Pettitt's test. For the region average, ET0 decreased from 1960 to 1993 by ?2.34 mm yr?2, while ET0 began to increase since 1994 by 4.80 mm yr?2. A differential equation method based on the Food and Agriculture Organization Penman–Monteith formula was used to attribute the change in ET0. The attribution results show that the significant decrease in wind speed dominated the change in ET0, which offset the effect of increasing air temperature and led to the decrease in ET0 from 1960 to 1993. However, wind speed began to increase, and the amplitude of increase in air temperature also rose significantly since the mid‐1990s. Increases in air temperature and wind speed together reversed the trend in ET0 and led to the increase in ET0 since 1994. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
18.
Spatiotemporal variation and driving forces of reference evapotranspiration in Jing River Basin,northwest China 总被引：1，自引：0，他引：1 下载免费PDF全文
下载免费PDF全文 Lihong Xu Zhongjie Shi Shulan Zhang Xinzheng Chu Pengtao Yu Wei Xiong Haijun Zuo Yunni Wang 《水文研究》2015,29(23):4846-4862
Evapotranspiration is an important component of the hydrological cycle, which integrates atmospheric demands and surface conditions. Research on spatial and temporal variations of reference evapotranspiration (ETo) enables understanding of climate change and its effects on hydrological processes and water resources. In this study, ETo was estimated by the FAO‐56 Penman–Monteith method in the Jing River Basin in China, based on daily data from 37 meteorological stations from 1960 to 2005. ETo trends were detected by the Mann–Kendall test in annual, seasonal, and monthly timescales. Sensitivity coefficients were used to examine the contribution of important meteorological variables to ETo. The influence of agricultural activities, especially irrigation on ETo was also analyzed. We found that ETo showed a decreasing trend in most of the basin in all seasons, except for autumn, which showed an increasing trend. Mean maximum temperature was generally the most sensitive parameter for ETo, followed by relative humidity, solar radiation, mean minimum temperature, and wind speed. Wind speed was the most dominant factor for the declining trend in ETo. The more significant decrease in ETo for agricultural and irrigation stations was mainly because of the more significant decrease in wind speed and sunshine hours, a mitigation in climate warming, and more significant increase in relative humidity compared with natural stations and non‐irrigation stations. Changes in ETo and the sensitivity coefficient of meteorological variables in relation to ETo were also affected by topography. Better understanding of ETo response to climate change will enable efficient use of agricultural production and water resources, which could improve the ecological environment in Jing River Basin. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
19.
Dan Zhang Xiaomang Liu Haoyuan Hong 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(8):1871-1881
Reference evapotranspiration (ET 0 ) is a key parameter in hydrological and meteorological studies. In this study, the FAO Penman–Monteith equation was used to estimate ET 0 , and the change in ET 0 was investigated in China from 1960 to 2011. The results show that a change point around the year 1993 was detected for the annual ET 0 series by the Cramer’s test. For the national average, annual ET 0 decreased significantly (P < 0.001) by ?14.35 mm/decade from 1960 to 1992, while ET 0 increased significantly (P < 0.05) by 22.40 mm/decade from 1993 to 2011. A differential equation method was used to attribute the change in ET 0 to climate variables. The attribution results indicate that ET 0 was most sensitive to change in vapor pressure, followed by solar radiation, air temperature and wind speed. However, the effective impact of change in climate variable on ET 0 was the product of the sensitivity and the change rate of climate variable. During 1960–1992, the decrease in solar radiation was the main reason of the decrease in ET 0 in humid region, while decrease in wind speed was the dominant factor of decreases in ET 0 in arid region and semi-arid/semi-humid region of China. Decrease in solar radiation and/or wind speed offset the effect of increasing air temperature on ET 0 , and together led to the decrease in ET 0 from 1960 to 1992. Since 1993, the rapidly increasing air temperature was the dominant factor to the change in ET 0 in all the three regions of China, which led to the increase in ET 0 . Furthermore, the future change in ET 0 was calculated under IPCC SRES A1B and B1 scenarios with projections from three GCMs. The results showed that increasing air temperature would dominate the change in ET 0 and ET 0 would increase by 2.13–10.77, 4.42–16.21 and 8.67–21.27 % during 2020s, 2050s and 2080s compared with the average annual ET 0 during 1960–1990, respectively. The increases in ET 0 would lead to the increase in agriculture water consumption in the 21st century and may aggravate the water shortage in China. 相似文献
20.
This study evaluates changes in streamflow, temperature and precipitation over a time span of 105 years (1906–2010) in the Colorado River Basin (CRB). Monthly precipitation and temperature data for 29 climate divisions, and streamflow data for 29 naturalized gauges were analyzed. Two variations of the Mann-Kendall test, considering lag-1 auto correlation and long-term persistence, and the Pettitt test were employed to assess trends and shifts, respectively. Results indicated that streamflow increased during the winter–spring months and decreased during the summer– autumn period. Decreasing trends in winter precipitation were identified over snow-dominated regions in the upper basin. Significant increases in temperature were detected over several months. Major shifts were noticed in 1964, 1968 and in the late 1920s. Increasing temperature while decreasing streamflow and precipitation were noticed after major shifts in the 1930s, and these shifts coincided with coupled phases of El Niño Southern Oscillation and Pacific Decadal Oscillation.
EDITOR A. Castellarin; ASSOCIATE EDITOR R. Hirsch 相似文献