In this article, annual evapotranspiration(ET) and net primary productivity (NPP) of fourtypes of vegetation were estimated for the Lushi basin,a subbasin of the Yellow River in China. These fourvegetation types inclu...In this article, annual evapotranspiration(ET) and net primary productivity (NPP) of fourtypes of vegetation were estimated for the Lushi basin,a subbasin of the Yellow River in China. These fourvegetation types include: deciduous broadleaf forest,evergreen needle leaf forest, dwarf shrub and grass.Biome-BGC--a biogeochemical process model wasused to calculate annual ET and NPP for eachvegetation type in the study area from 1954 to 2000.Daily microclimate data of 47 years monitored byLushi meteorological station was extrapolated tocover the basin using MT-CLIM, a mountainmicroclimate simulator. The output files of MT-CLIM were used to feed Biome-BGC. We usedaverage ecophysiological values of each type ofvegetation supplied by Numerical TerradynamicSimulation Group (NTSG) in the University ofMontana as input ecophysiological constants file.The estimates of daily NPP in early July and annualET on these four biome groups were comparedrespectively with field measurements and other studies.Daily gross primary production (GPP) of evergreenneedle leaf forest measurements were very close tothe output of Biome-BGC, but measurements ofbroadleaf forest and dwarf shrub were much smallerthan the simulation result. Simulated annual ET andNPP had a significant correlation with precipitation,indicating precipitation is the major environmentalfactor affecting ET and NPP in the study area.Precipitation also is the key climatic factor for theinterannual ET and NPP variations.展开更多
The consistency of global atmospheric mass and water budget performance in 20 state-of-the-art ocean-atmosphere Coupled Model Intercomparison Project Phase 5(CMIP5) coupled models has been assessed in a historical exp...The consistency of global atmospheric mass and water budget performance in 20 state-of-the-art ocean-atmosphere Coupled Model Intercomparison Project Phase 5(CMIP5) coupled models has been assessed in a historical experiment. All the models realistically reproduce a climatological annual mean of global air mass(AM) close to the ERA-Interim AM during 1989-2005. Surprisingly, the global AM in half of the models shows nearly no seasonal variation,which does not agree with the seasonal processes of global precipitable water or water vapor, given the mass conservation constraint. To better understand the inconsistencies, we evaluated the seasonal cycles of global AM tendency and water vapor source(evaporation minus precipitation). The results suggest that the inconsistencies result from the poor balance between global AM tendency and water vapor source based on the global AM budget equation. Moreover, the cross-equatorial dry air mass flux, or hemispheric dry mass divergence, is not well represented in any of the 20 CMIP5 models, which show a poorly matched seasonal cycle and notably larger amplitude, compared with the hemispheric tendencies of dry AM in both the Northern Hemisphere and Southern Hemisphere. Pronounced erroneous estimations of tropical precipitation also occur in these models. We speculate that the large inaccuracy of precipitation and possibly evaporation in the tropics is one of the key factors for the inconsistent cross-equatorial mass flux. A reasonable cross-equatorial mass flux in well-balanced hemispheric air mass and moisture budgets remains a challenge for both reanalysis assimilation systems and climate modeling.展开更多
The study aims to identify a suitable site for open and bore well in a farmhouseusing ground magnetic survey in south India.It also aims to define depth to granitoid and structural elements which traverse the selected...The study aims to identify a suitable site for open and bore well in a farmhouseusing ground magnetic survey in south India.It also aims to define depth to granitoid and structural elements which traverse the selected area.Magnetic data(n=84)measured,processed and interpreted as qualitative and quantitatively.The results of total magnetic intensities indicate that the area is composed of linear magnetic lows trending NE-SW direction and circular to semi-circular causative bodies.The magnetic values ranged from-137 nT to 2345 nT with a mean of 465 nT.Reduction to equator shows significant shifting of causative bodies in the southern and northern directions.Analytical signal map shows exact boundary of granitic bodies.Cosine directional filter has brought out structural element trending NE-SW direction.Results of individual profile brought to light structurally weak zone between 90 m and 100 m in all the profile lines.Sudden decrease of magnetic values from 2042 nT to 126 nT noticed in profile line 6 between 20 m and 30 m indicates fault occurrence.Magnetic breaks obtained from these maps were visualized,interpreted and identified two suitable sites for open and bore well.Radially averaged power spectrum estimates depth of shallow and deep sources in 5 m and 50 m,respectively.Euler method has also been applied to estimate depth of granitoid and structural elements using structural indexes 0,1,2,and 3 and found depth ranges from<10 m to>90 m.Study indicates magnetic method is one of the geophysical methods suitable for groundwater exploration and site selection for open and borewells.展开更多
This study evaluates the alternative conceptual models for groundwater modelling.A true model was created with a synthetic alluvial fan-plain hydrogeological framework.Various alternative conceptual models were evalua...This study evaluates the alternative conceptual models for groundwater modelling.A true model was created with a synthetic alluvial fan-plain hydrogeological framework.Various alternative conceptual models were evaluated for groundwater flow simulations.The first alternative model is a single aquifer layer model;the second alternative model is a 3-layer aquifer model;and the third model is a 5-layer model consisting of 3 aquifers separated by 2 aquitards.All models could fit very well to the observations with optimized values of hydraulic conductivities.However,the single aquifer layer model can only compute water balance components with good accuracy.The 3-layer aquifer model can be used for water balance computation and groundwater head simulation with small errors.The 5-layer model is capable of simulating water budget,groundwater head distribution and travel times with high accuracy.Multimodel analysis found only the 3rd alternative model superior.展开更多
The objective of this study was to analyze the water budget of a small basin in the northern of Loess Plateau. A small basin, Liudaogou in the northern Loess Plateau was chosen as the study area. The numerical calcula...The objective of this study was to analyze the water budget of a small basin in the northern of Loess Plateau. A small basin, Liudaogou in the northern Loess Plateau was chosen as the study area. The numerical calculation of surface runoff was applied to results of the field survey, and components of monthly water budget were estimated. The unit area of 1 km2 was selected as the index area for the estimation. A component of habitant water consumption was added to the water budget to consider the contribution of human activity. Results indicated that the water storage was negative in May, June and July while the annual amount was approximately 0.0. Evaportanspiration attained maximum in August and its annual total accounted for 74.2% of annual precipitation. Results of this study are significant for the sustainable water conservation and utilization in the northern of Loess Plateau where annual water resources are relatively deficient.展开更多
The spatiotemporal variations of water vapor budget(Bt)and their relationships with local precipitation over the Tibetan Plateau(TP)are critical for understanding the characteristics of spatial distributions and evolu...The spatiotemporal variations of water vapor budget(Bt)and their relationships with local precipitation over the Tibetan Plateau(TP)are critical for understanding the characteristics of spatial distributions and evolutions of water resources over the TP.Based on a boundary of the TP,this paper explored the spatiotemporal characteristics of Bt over the TP using the European Centre for Medium-Range Weather Forecasts interim(ERA-Interim)reanalysis datasets.On the climatological mean,the TP is a water vapor sink throughout four seasons and the seasonal variation of Bt is closely associated with the water vapor budget at the southern boundary of the TP.The transient water vapor transport is quasimeridional in the mid-and high-latitude areas and plays a leading role in winter Bt but contributes little in other seasons.At the interannual timescale,the variation of Bt is mainly determined by anomalous water vapor transports at the western and southern boundaries.The Bay of Bengal,the North Arabian Sea,and mid-latitude West Asia are the main sources of excessive water vapor for a wetter TP.At the southern and western boundaries,the transient water vapor budget regulates one-third to four-fifths of Bt anomalies.Moreover,the variability of the TP Bt is closely associated with precipitation over the central-southern and southeastern parts of the TP in summer and winter,which is attributed to the combined effect of the stationary and transient water vapor budgets.Given the role of the transient water vapor transport,the linkage between the TP Bt and local precipitation is tighter.展开更多
A paired basin study in the upper Santa Fe River watershed following forest thinning and prescribed burns successfully measured water budget components in a treated and an untreated (control) basin. The paired basin s...A paired basin study in the upper Santa Fe River watershed following forest thinning and prescribed burns successfully measured water budget components in a treated and an untreated (control) basin. The paired basin study was established to investigate questions that have arisen regarding changes in water yield from forest treatments. Precipitation, stream flow, soil moisture, and chloride concentrations in precipitation and stream flow were measured to quantify the water budget components. The results from eleven years of data collection and analysis have a high degree of confidence with respect to measuring the water budget components based on the mass balance of water and chloride. The differences in the geologic structure and topography between the two paired basins appeared to impact the water budgets more than the forest treatments, except during periods when winter precipitation and snowmelt represented a significant component of inflow. Although this paired basin study was not able to portray a simple relationship between forest thinning and water yield, the chloride concentration methodology used to estimate evapotranspiration (ET) was successful. These detailed observations of chloride deposition and transport characteristics may be relevant for other researchers working in forested basins with substantial ET. ET rates were estimated by examining the cycle of chloride entering and exiting each basin over six integration periods. ET was estimated to be about 90% to 94% of precipitation in the treated basin and 77% to 86% in the control basin. The higher ET in the treated basin both before and after forest treatments may be due to the much greater area of west-facing hillslopes in the treated basin, which receive warm afternoon sun, and the greater area of rock cover in the control basin. Variation in the chloride concentration of collected precipitation samples from different sites indicates that horizontal precipitation of chloride in the tree canopy is an important consideration when using the chloride mass balance approach to calculate water budget components.展开更多
Background:Central Himalayan forested catchments provide fresh water supply and innumerable ecosystem services to millions of people.Hence,the understanding of linkages between forests and water is very crucial for av...Background:Central Himalayan forested catchments provide fresh water supply and innumerable ecosystem services to millions of people.Hence,the understanding of linkages between forests and water is very crucial for availability and quality of water at catchment scale.Therefore,the present study aims to understand the hydrological response of two forested catchments(namely,Arnigad and Bansigad)in the Central Himalayan Region.Methods:Threeyears’data(March,2008 to February,2011)were collected from meteorological and hydrological stations in Arnigad and Bansigad catchments.The present paper describes the mean hydrological response of these forested catchments investigated through detailed field investigation.Results:The annual hyetograph analysis revealed that the rainfall at both the catchments was highly seasonal,and wetperiod(June–September)plays a key role in catchment functioning.Exceedance of rainfall threshold of^200 mm(~10%of annual rainfall)significantly increased streamflow generation in both catchments.In Arnigad,the stream was perennial with a mean baseflow of^83mm per month(~6%of annual baseflow)whereas,Bansigad had greater seasonality due to lack of streamflow during the prewetperiod(March–May).Separation of hydrographs in Arnigad and Bansigad catchments i.e.stormflow(6%and 31%,respectively)and baseflow(50%and 32%,respectively)helped to understand the probability of flooding during wetperiod and drought during dryperiod.The forest ecosystem in Arnigad displayed healthier hydrological functioning in terms of reduced stormflow(82%),and enhanced baseflow(52%),soil moisture(13%),steady infiltration rate(22%)and lag time(~15 min)relative to Bansigad.These enhanced values indicated soil capability to store water in the forested catchment(Arnigad)and helped to understand the volume of water(discharge)that was available during dryperiod.The lower denudation rate at Arnigad by 41%resulted in decreased suspended sediment(18%)and bed load(75%)compared to Bansigad.Further,the enhanced dissolved solids in the Arnigad stream resulted from the higher organic matter generated in the forest floor.Conclusion:This study shows that rainfall during the wetperiod was the main driver of hydrological functioning,whereas,forests provided substantial services by regulating water balance,soil moisture and sediment budget through different mechanisms of forest components at catchmentscale in the Central Himalayan Region.展开更多
Water budget closure is a method used to study the balance of basin water storage and the dynamics of relevant hydrological components(e.g.,precipitation,evapotranspiration,and runoff).When water budget closure is con...Water budget closure is a method used to study the balance of basin water storage and the dynamics of relevant hydrological components(e.g.,precipitation,evapotranspiration,and runoff).When water budget closure is connected with terrestrial water storage change(TWSC)estimated from Gravity Recovery and Climate Experiment(GRACE)data,variations in basin runoff can be understood comprehensively.In this study,total runoff variations in the Yangtze River Basin(YRB)and its sub-basins are examined in detail based on the water budget closure equation.We compare and combine mainstream precipitation and evapotranspiration models to determine the best estimate of precipitation minus evapotranspiration.In addition,we consider human water consumption,which has been neglected in earlier studies,and discuss its impact.To evaluate the effectiveness and accuracy of the combined hydrological models in estimating subsurface runoff,we collect discharge variations derived from in situ observations in the YRB and its sub-basins and compare these data with the models’final estimated runoff variations.The estimated runoff variations suggest that runoff over the YRB has been increasing,especially in the lower sub-basins and in the post-monsoon season,and is accompanied by apparent terrestrial water loss.展开更多
This study investigated the cloud microphysical processes and atmospheric water budget during the extreme precipitation event on 20 July 2021 in Zhengzhou of Henan Province,China,based on observations,reanalysis data,...This study investigated the cloud microphysical processes and atmospheric water budget during the extreme precipitation event on 20 July 2021 in Zhengzhou of Henan Province,China,based on observations,reanalysis data,and the results from the high-resolution large-eddy simulation nested in the Weather Research and Forecasting(WRF)model with assimilation of satellite and radar observations.The results show that the abundant and persistent southeasterly supply of water vapor,induced by Typhoons In-Fa and Cempaka,under a particular synoptic pattern featured with abnormal northwestward displacement of the western Pacific subtropical high,was conducive to warm rain processes through a high vapor condensation rate of cloud water and an efficient collision–coalescence process of cloud water to rainwater.Such conditions were favorable for the formation and maintenance of the quasi-stationary warmsector heavy rainfall.Precipitation formation through the collision–coalescence process of cloud water to rainwater accounted for approximately 70%of the total,while the melting of snow and graupel accounted for only approximately 30%,indicating that warm cloud processes played a dominant role in this extreme rainfall event.However,enhancement of cold cloud processes promoted by latent heat release also exerted positive effect on rainfall during the period of most intense hourly rainfall.It was also found that rainwater advection from outside of Zhengzhou City played an important role in maintaining the extreme precipitation event.展开更多
Owing to the scarcity of observation data in the western Tibetan Plateau(TP),the knowledge of precipitation changes over the entire plateau based only on the limited data in eastern TP is not reliable.Therefore,the al...Owing to the scarcity of observation data in the western Tibetan Plateau(TP),the knowledge of precipitation changes over the entire plateau based only on the limited data in eastern TP is not reliable.Therefore,the alternative high-resolution precipitation data of the China Meteorological Forcing Dataset(CMFD)are used for the comprehensive analysis of precipitation changes over the whole TP(including western and northern TP)to fill in the lack of understanding of precipitation in the western TP.Compared with observations,CMFD can broadly capture the spatial distributions and identify the temporal variabilities of precipitation over the TP.Results with CMFD data suggested that the annual precipitation over the whole TP did not show a uniform humidification trend in 1979-2018 and featured wetting and drying trends in the northern(NTP)and southern TP(STP),respectively.Additionally,the four seasonal regimes of precipitation over the northern TP(NTP,including most areas of western TP)all experienced a noticeable interdecadal shift around the late 1990s,followed by above-normal precipitation.Except for spring,the seasonal precipitation over the southern TP(STP)showed interannual variations.Spring precipitation over the STP has undergone moistening since the late 1990s,which was consistent with that over the NTP.Four different reanalysis datasets,namely JRA55,MERRA2,ERA5 and CRA40,were used to compare the water vapour budget of each boundary over the TP.The increase in spring precipitation over the NTP and STP was found to be related to the decrease in water vapour outflow from the north boundary.The interdecadal increase in summer precipitation over the NTP was mainly due to the reduction of outflow from the east boundary.Finally,the increase in autumn precipitation was related to the increase in inflow from the west boundary.展开更多
The Three-River Headwaters(TRH)region in the Tibetan Plateau is vulnerable to climate change;changes in summer(June–August)precipitation have a significant impact on water security and sustainability in both local an...The Three-River Headwaters(TRH)region in the Tibetan Plateau is vulnerable to climate change;changes in summer(June–August)precipitation have a significant impact on water security and sustainability in both local and downstream areas.However,the changes in summer precipitation of different intensities over the TRH region,along with their influencing factors,remain unclear.In this study,we used observational and ERA5 reanalysis data and employed a precipitation categorization and water vapor budget analysis to quantify the categorized precipitation variations and investigate their possible linkages with the water vapor budget.Our results showed an increasing trend in summer precipitation at a rate of 0.9 per year(p<0.1)during 1979–2020,with a significant dry-to-wet transition in 2002.The category‘very heavy precipitation’(10 mm d−1)contributed 65.1%of the increased summer precipitation,which occurred frequently in the northern TRH region.The dry-to-wet transition was caused by the effects of varied atmospheric circulations in each subregion.Southwesterly water vapor transport through the southern boundary was responsible for the increased net water vapor flux in the western TRH region(158.2%),while southeasterly water vapor transport through the eastern boundary was responsible for the increased net water vapor flux in the central TRH(155.2%)and eastern TRH(229.2%)regions.Therefore,we inferred that the dry-to-wet transition of summer precipitation and the increased‘very heavy precipitation’over the TRH was caused by increased easterly and southerly water vapor transport.展开更多
The Soil and Water Assessment Tool(SWAT)model was used to assess the impacts of different land use scenarios on hydrological processes in the Fuhe watershed in Poyang Lake Basin,East China.A total of 12 model paramete...The Soil and Water Assessment Tool(SWAT)model was used to assess the impacts of different land use scenarios on hydrological processes in the Fuhe watershed in Poyang Lake Basin,East China.A total of 12 model parameters were calibrated with observed monthly runoff data for 1982-1988 and validated for 1991-1998 for baseline conditions.The baseline test results of R2 and Nash-Sutcliffe model efficiency(NSE)values ranged between 0.88 and 0.94 across the calibration and validation periods,indicating that SWAT accurately replicated the Fuhe watershed streamflow.Several different land use scenarios were then simulated with the model,focusing on the impacts of land use change on the hydrology of the watershed.The results of hypothetical scenario simulations revealed that surface runoff declined while groundwater recharge and evapotranspiration(ET)increased,as forest land,agriculture land and/or grassland areas increased,as well as when paddy field and urban areas decreased.These results further showed that forest land has a higher capacity to conserve the water as compared to pasture land.The results of the real scenario simulations revealed that urbanization is the strongest contributor to changes in surface runoff,water yield,and ET.Urbanization can be considered as a potential major environmental stressor controlling hydrological components.展开更多
Introduction:Forest cover in Hungary has increased from 1.1 to 2.0 million hectares during the last century.The EU(European Union)promotes further afforestation;thus,15,000–18,000 ha are being forested each year,main...Introduction:Forest cover in Hungary has increased from 1.1 to 2.0 million hectares during the last century.The EU(European Union)promotes further afforestation;thus,15,000–18,000 ha are being forested each year,mainly in the Hungarian Great Plain.In terms of species used for afforestation,poplar plantations are preferred over native oak woodlands.The groundwater uptake of trees can be a significant water balance element of forested areas in shallow groundwater environments within the Hungarian Great Plain.Forests can cause water table depressions and subsurface salt accumulation in areas with negative water balance.This study examined the hydrological impact of forest cover in the Hungarian Great Plain.Within the framework of this research,climatic water balance,water table depth and salinity,subsoil layering,tree species and stand age were analysed as influencing factors.This paper compares the effect which an oak forest,a poplar plantation and a pasture have on groundwater uptake and salt accumulation.Results:The water table level was roughly 0.4–0.5 m lower beneath the oak forest and the poplar plantation than it was beneath the pasture.Forest groundwater use was 1.5–2 times higher than that of grassland.Groundwater uptake of oak forest was greater than that of poplar plantation during the monitoring period.Salt accumulation,which shows water use in the longer run,was slightly higher for poplar in deeper layers.Conclusions:The greater amount of groundwater used by trees does not lead to a higher salt uptake as only a slight accumulation of salt was measured beneath the forests.Overall,hybrid poplar was slightly less favourable than native oak when considering salinization effects.However,even greater groundwater uptake by trees over longer timescales could cause more significant salt accumulation under pronounced drought conditions due to climate change.展开更多
In this paper,synoptic-scale analyses of frontogenesis,moisture budget,and tropospheric diabatic heating are performed to reveal the development and maintenance mechanisms for the extreme heavy rainfall in Henan Provi...In this paper,synoptic-scale analyses of frontogenesis,moisture budget,and tropospheric diabatic heating are performed to reveal the development and maintenance mechanisms for the extreme heavy rainfall in Henan Province of central China from 19 to 21 July 2021,based on station observations and the ECMWF Reanalysis version 5(ERA5)data.The results demonstrate that owing to the blocking effect of local topography,low-level wind convergence in Henan appeared underneath high-level divergence,conducive to development and maintenance of a midtropospheric low-pressure system saddled by the Asian continental high and the western Pacific subtropical high(WPSH),during the extreme heavy rainfall.In the lower troposphere,frontogenesis occurred in the θ_(se) intensive region,as a result of the divergence and horizontal deformation(which play equally important roles),generating frontal secondary circulation with strong vertical motion favorable to heavy rainfall.Moisture budget analysis reveals that 1)with the continuous strengthening of the easterly wind from the north side of Typhoon In-Fa(2106),strong wind shear and orographic uplift led to abnormally strong convergence of water vapor flux in the boundary layer in Henan;2)there occurred extremely strong net inflow of moisture in the boundary layer from the east.Horizontally,both the apparent heat source and the moisture sink coincided with the area of heavy rainfall;vertically,however,Q_(1)exhibited a single peak with the heating center in the middle and upper troposphere,while large Q_(2)values evenly resided over 850–400 hPa;and Q_(1)(Q_(2))was dominated by vertical(horizontal)transport of potential temperature(moisture).These indicate that the latent heat release from condensation of initial heavy rainfall provided a positive feedback,leading to increasingly heavy precipitation.All these synoptic settings sustained the extreme rainfall process.展开更多
Due to their huge socio-economic impacts and complex formation causes,extreme and continuous drought events have become the focus and nodus of research in recent years.In the midsummer(July-August)of 2022,a severe dro...Due to their huge socio-economic impacts and complex formation causes,extreme and continuous drought events have become the focus and nodus of research in recent years.In the midsummer(July-August)of 2022,a severe drought event occurred in the whole Yangtze River Basin(YRB),China.During that period,the precipitation in the upper,middle and lower reaches of the YRB dropped over 40%less than the 1961-2021 climatic mean,which had never happened previously.Furthermore,the temperature was the highest during 1961-2022.The record-breaking magnitude of less rainfall and high temperature directly led to the continuous development of this extreme drought event.An atmospheric moisture budget analysis revealed that the YRB midsummer rainfall anomaly was dominated by the anomalous powerful vertical moisture advection,which was derived from the strongest descending motion over the whole YRB in the 2022 midsummer during 1981-2022.The western Pacific subtropical high(WPSH)during the midsummer remained stronger,more westward and lasted longer than the climatic mean.As a result,the whole YRB was controlled by a positive geopotential height centre.Further evidence revealed that the anomalous subtropical zonal flow played a crucial role in inducing the extreme descent over the YRB.Moreover,the anomalous upper-tropospheric easterly flow over the YRB in 2022 is the strongest during 1981-2022,modulating the generation of the unprecedented descent anomaly over the YRB.The likelihood that an integrated connection of severe drought in East Asia and flood in West Asia and northwestern South Asia would increase when the extremely strong easterly anomalies in the upper troposphere emerged and induced descending adiabatic flow on the eastern sides of the Tibetan Plateau.The results of this study can provide scientific insights into the predictability of extreme drought events and provide ways to improve predictions.展开更多
文摘In this article, annual evapotranspiration(ET) and net primary productivity (NPP) of fourtypes of vegetation were estimated for the Lushi basin,a subbasin of the Yellow River in China. These fourvegetation types include: deciduous broadleaf forest,evergreen needle leaf forest, dwarf shrub and grass.Biome-BGC--a biogeochemical process model wasused to calculate annual ET and NPP for eachvegetation type in the study area from 1954 to 2000.Daily microclimate data of 47 years monitored byLushi meteorological station was extrapolated tocover the basin using MT-CLIM, a mountainmicroclimate simulator. The output files of MT-CLIM were used to feed Biome-BGC. We usedaverage ecophysiological values of each type ofvegetation supplied by Numerical TerradynamicSimulation Group (NTSG) in the University ofMontana as input ecophysiological constants file.The estimates of daily NPP in early July and annualET on these four biome groups were comparedrespectively with field measurements and other studies.Daily gross primary production (GPP) of evergreenneedle leaf forest measurements were very close tothe output of Biome-BGC, but measurements ofbroadleaf forest and dwarf shrub were much smallerthan the simulation result. Simulated annual ET andNPP had a significant correlation with precipitation,indicating precipitation is the major environmentalfactor affecting ET and NPP in the study area.Precipitation also is the key climatic factor for theinterannual ET and NPP variations.
基金Natural Science Foundation of Jiangsu Province grant(BK2012465)National Natural Science Foundation of China(41205065,41475045,41005046)+1 种基金National Basic Research Program of China(2010CB428602)Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institution
文摘The consistency of global atmospheric mass and water budget performance in 20 state-of-the-art ocean-atmosphere Coupled Model Intercomparison Project Phase 5(CMIP5) coupled models has been assessed in a historical experiment. All the models realistically reproduce a climatological annual mean of global air mass(AM) close to the ERA-Interim AM during 1989-2005. Surprisingly, the global AM in half of the models shows nearly no seasonal variation,which does not agree with the seasonal processes of global precipitable water or water vapor, given the mass conservation constraint. To better understand the inconsistencies, we evaluated the seasonal cycles of global AM tendency and water vapor source(evaporation minus precipitation). The results suggest that the inconsistencies result from the poor balance between global AM tendency and water vapor source based on the global AM budget equation. Moreover, the cross-equatorial dry air mass flux, or hemispheric dry mass divergence, is not well represented in any of the 20 CMIP5 models, which show a poorly matched seasonal cycle and notably larger amplitude, compared with the hemispheric tendencies of dry AM in both the Northern Hemisphere and Southern Hemisphere. Pronounced erroneous estimations of tropical precipitation also occur in these models. We speculate that the large inaccuracy of precipitation and possibly evaporation in the tropics is one of the key factors for the inconsistent cross-equatorial mass flux. A reasonable cross-equatorial mass flux in well-balanced hemispheric air mass and moisture budgets remains a challenge for both reanalysis assimilation systems and climate modeling.
文摘The study aims to identify a suitable site for open and bore well in a farmhouseusing ground magnetic survey in south India.It also aims to define depth to granitoid and structural elements which traverse the selected area.Magnetic data(n=84)measured,processed and interpreted as qualitative and quantitatively.The results of total magnetic intensities indicate that the area is composed of linear magnetic lows trending NE-SW direction and circular to semi-circular causative bodies.The magnetic values ranged from-137 nT to 2345 nT with a mean of 465 nT.Reduction to equator shows significant shifting of causative bodies in the southern and northern directions.Analytical signal map shows exact boundary of granitic bodies.Cosine directional filter has brought out structural element trending NE-SW direction.Results of individual profile brought to light structurally weak zone between 90 m and 100 m in all the profile lines.Sudden decrease of magnetic values from 2042 nT to 126 nT noticed in profile line 6 between 20 m and 30 m indicates fault occurrence.Magnetic breaks obtained from these maps were visualized,interpreted and identified two suitable sites for open and bore well.Radially averaged power spectrum estimates depth of shallow and deep sources in 5 m and 50 m,respectively.Euler method has also been applied to estimate depth of granitoid and structural elements using structural indexes 0,1,2,and 3 and found depth ranges from<10 m to>90 m.Study indicates magnetic method is one of the geophysical methods suitable for groundwater exploration and site selection for open and borewells.
文摘This study evaluates the alternative conceptual models for groundwater modelling.A true model was created with a synthetic alluvial fan-plain hydrogeological framework.Various alternative conceptual models were evaluated for groundwater flow simulations.The first alternative model is a single aquifer layer model;the second alternative model is a 3-layer aquifer model;and the third model is a 5-layer model consisting of 3 aquifers separated by 2 aquitards.All models could fit very well to the observations with optimized values of hydraulic conductivities.However,the single aquifer layer model can only compute water balance components with good accuracy.The 3-layer aquifer model can be used for water balance computation and groundwater head simulation with small errors.The 5-layer model is capable of simulating water budget,groundwater head distribution and travel times with high accuracy.Multimodel analysis found only the 3rd alternative model superior.
基金Supported by JSPS Core University Program, Japan CAS "Western Light" (2006YB04)
文摘The objective of this study was to analyze the water budget of a small basin in the northern of Loess Plateau. A small basin, Liudaogou in the northern Loess Plateau was chosen as the study area. The numerical calculation of surface runoff was applied to results of the field survey, and components of monthly water budget were estimated. The unit area of 1 km2 was selected as the index area for the estimation. A component of habitant water consumption was added to the water budget to consider the contribution of human activity. Results indicated that the water storage was negative in May, June and July while the annual amount was approximately 0.0. Evaportanspiration attained maximum in August and its annual total accounted for 74.2% of annual precipitation. Results of this study are significant for the sustainable water conservation and utilization in the northern of Loess Plateau where annual water resources are relatively deficient.
基金Second Scientific Expedition on the Qinghai-Tibet Plateau(2019QZKK020803)Strategic Priority Research Program of Chinese Academy of Sciences Pan-Third Pole Environment Study for a Green Silk Road(XDA2010030807)。
文摘The spatiotemporal variations of water vapor budget(Bt)and their relationships with local precipitation over the Tibetan Plateau(TP)are critical for understanding the characteristics of spatial distributions and evolutions of water resources over the TP.Based on a boundary of the TP,this paper explored the spatiotemporal characteristics of Bt over the TP using the European Centre for Medium-Range Weather Forecasts interim(ERA-Interim)reanalysis datasets.On the climatological mean,the TP is a water vapor sink throughout four seasons and the seasonal variation of Bt is closely associated with the water vapor budget at the southern boundary of the TP.The transient water vapor transport is quasimeridional in the mid-and high-latitude areas and plays a leading role in winter Bt but contributes little in other seasons.At the interannual timescale,the variation of Bt is mainly determined by anomalous water vapor transports at the western and southern boundaries.The Bay of Bengal,the North Arabian Sea,and mid-latitude West Asia are the main sources of excessive water vapor for a wetter TP.At the southern and western boundaries,the transient water vapor budget regulates one-third to four-fifths of Bt anomalies.Moreover,the variability of the TP Bt is closely associated with precipitation over the central-southern and southeastern parts of the TP in summer and winter,which is attributed to the combined effect of the stationary and transient water vapor budgets.Given the role of the transient water vapor transport,the linkage between the TP Bt and local precipitation is tighter.
文摘A paired basin study in the upper Santa Fe River watershed following forest thinning and prescribed burns successfully measured water budget components in a treated and an untreated (control) basin. The paired basin study was established to investigate questions that have arisen regarding changes in water yield from forest treatments. Precipitation, stream flow, soil moisture, and chloride concentrations in precipitation and stream flow were measured to quantify the water budget components. The results from eleven years of data collection and analysis have a high degree of confidence with respect to measuring the water budget components based on the mass balance of water and chloride. The differences in the geologic structure and topography between the two paired basins appeared to impact the water budgets more than the forest treatments, except during periods when winter precipitation and snowmelt represented a significant component of inflow. Although this paired basin study was not able to portray a simple relationship between forest thinning and water yield, the chloride concentration methodology used to estimate evapotranspiration (ET) was successful. These detailed observations of chloride deposition and transport characteristics may be relevant for other researchers working in forested basins with substantial ET. ET rates were estimated by examining the cycle of chloride entering and exiting each basin over six integration periods. ET was estimated to be about 90% to 94% of precipitation in the treated basin and 77% to 86% in the control basin. The higher ET in the treated basin both before and after forest treatments may be due to the much greater area of west-facing hillslopes in the treated basin, which receive warm afternoon sun, and the greater area of rock cover in the control basin. Variation in the chloride concentration of collected precipitation samples from different sites indicates that horizontal precipitation of chloride in the tree canopy is an important consideration when using the chloride mass balance approach to calculate water budget components.
文摘Background:Central Himalayan forested catchments provide fresh water supply and innumerable ecosystem services to millions of people.Hence,the understanding of linkages between forests and water is very crucial for availability and quality of water at catchment scale.Therefore,the present study aims to understand the hydrological response of two forested catchments(namely,Arnigad and Bansigad)in the Central Himalayan Region.Methods:Threeyears’data(March,2008 to February,2011)were collected from meteorological and hydrological stations in Arnigad and Bansigad catchments.The present paper describes the mean hydrological response of these forested catchments investigated through detailed field investigation.Results:The annual hyetograph analysis revealed that the rainfall at both the catchments was highly seasonal,and wetperiod(June–September)plays a key role in catchment functioning.Exceedance of rainfall threshold of^200 mm(~10%of annual rainfall)significantly increased streamflow generation in both catchments.In Arnigad,the stream was perennial with a mean baseflow of^83mm per month(~6%of annual baseflow)whereas,Bansigad had greater seasonality due to lack of streamflow during the prewetperiod(March–May).Separation of hydrographs in Arnigad and Bansigad catchments i.e.stormflow(6%and 31%,respectively)and baseflow(50%and 32%,respectively)helped to understand the probability of flooding during wetperiod and drought during dryperiod.The forest ecosystem in Arnigad displayed healthier hydrological functioning in terms of reduced stormflow(82%),and enhanced baseflow(52%),soil moisture(13%),steady infiltration rate(22%)and lag time(~15 min)relative to Bansigad.These enhanced values indicated soil capability to store water in the forested catchment(Arnigad)and helped to understand the volume of water(discharge)that was available during dryperiod.The lower denudation rate at Arnigad by 41%resulted in decreased suspended sediment(18%)and bed load(75%)compared to Bansigad.Further,the enhanced dissolved solids in the Arnigad stream resulted from the higher organic matter generated in the forest floor.Conclusion:This study shows that rainfall during the wetperiod was the main driver of hydrological functioning,whereas,forests provided substantial services by regulating water balance,soil moisture and sediment budget through different mechanisms of forest components at catchmentscale in the Central Himalayan Region.
基金supported by the National Natural Science Foundation of China(41974093,41774088,41331066 and 42174097)the Key Research Project of Frontier Bureau of Chinese Academy of Sciences(qyzdy-ssw-sys003).
文摘Water budget closure is a method used to study the balance of basin water storage and the dynamics of relevant hydrological components(e.g.,precipitation,evapotranspiration,and runoff).When water budget closure is connected with terrestrial water storage change(TWSC)estimated from Gravity Recovery and Climate Experiment(GRACE)data,variations in basin runoff can be understood comprehensively.In this study,total runoff variations in the Yangtze River Basin(YRB)and its sub-basins are examined in detail based on the water budget closure equation.We compare and combine mainstream precipitation and evapotranspiration models to determine the best estimate of precipitation minus evapotranspiration.In addition,we consider human water consumption,which has been neglected in earlier studies,and discuss its impact.To evaluate the effectiveness and accuracy of the combined hydrological models in estimating subsurface runoff,we collect discharge variations derived from in situ observations in the YRB and its sub-basins and compare these data with the models’final estimated runoff variations.The estimated runoff variations suggest that runoff over the YRB has been increasing,especially in the lower sub-basins and in the post-monsoon season,and is accompanied by apparent terrestrial water loss.
基金Supported by the National Key Research and Development Program of China (2016YFE0201900-02 and 2019YFC1510304)National Natural Science Foundation of China (41575037)。
文摘This study investigated the cloud microphysical processes and atmospheric water budget during the extreme precipitation event on 20 July 2021 in Zhengzhou of Henan Province,China,based on observations,reanalysis data,and the results from the high-resolution large-eddy simulation nested in the Weather Research and Forecasting(WRF)model with assimilation of satellite and radar observations.The results show that the abundant and persistent southeasterly supply of water vapor,induced by Typhoons In-Fa and Cempaka,under a particular synoptic pattern featured with abnormal northwestward displacement of the western Pacific subtropical high,was conducive to warm rain processes through a high vapor condensation rate of cloud water and an efficient collision–coalescence process of cloud water to rainwater.Such conditions were favorable for the formation and maintenance of the quasi-stationary warmsector heavy rainfall.Precipitation formation through the collision–coalescence process of cloud water to rainwater accounted for approximately 70%of the total,while the melting of snow and graupel accounted for only approximately 30%,indicating that warm cloud processes played a dominant role in this extreme rainfall event.However,enhancement of cold cloud processes promoted by latent heat release also exerted positive effect on rainfall during the period of most intense hourly rainfall.It was also found that rainwater advection from outside of Zhengzhou City played an important role in maintaining the extreme precipitation event.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)programme(2019QZKK0102 and 2019QZKK0208)China Three Gorges Corporation(0704181)+1 种基金Innovation and development special project of China Meteorological Administration(CXFZ 2022J039)Key Innovation Team of China Meteorological Administration Climate Change Detection,Impact and Response(CMA2022ZD03).
文摘Owing to the scarcity of observation data in the western Tibetan Plateau(TP),the knowledge of precipitation changes over the entire plateau based only on the limited data in eastern TP is not reliable.Therefore,the alternative high-resolution precipitation data of the China Meteorological Forcing Dataset(CMFD)are used for the comprehensive analysis of precipitation changes over the whole TP(including western and northern TP)to fill in the lack of understanding of precipitation in the western TP.Compared with observations,CMFD can broadly capture the spatial distributions and identify the temporal variabilities of precipitation over the TP.Results with CMFD data suggested that the annual precipitation over the whole TP did not show a uniform humidification trend in 1979-2018 and featured wetting and drying trends in the northern(NTP)and southern TP(STP),respectively.Additionally,the four seasonal regimes of precipitation over the northern TP(NTP,including most areas of western TP)all experienced a noticeable interdecadal shift around the late 1990s,followed by above-normal precipitation.Except for spring,the seasonal precipitation over the southern TP(STP)showed interannual variations.Spring precipitation over the STP has undergone moistening since the late 1990s,which was consistent with that over the NTP.Four different reanalysis datasets,namely JRA55,MERRA2,ERA5 and CRA40,were used to compare the water vapour budget of each boundary over the TP.The increase in spring precipitation over the NTP and STP was found to be related to the decrease in water vapour outflow from the north boundary.The interdecadal increase in summer precipitation over the NTP was mainly due to the reduction of outflow from the east boundary.Finally,the increase in autumn precipitation was related to the increase in inflow from the west boundary.
基金supported by Science and Technology Project of China Huaneng Research on Integrated Meteorology and Hydrology Forecasting System in Lancang River Basin(HNKJ21-HF241)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(2019QZKK0207-02)+1 种基金the Research Programme of the Kunming Engineering Corporation Limited(DJ-HXGG-2021-04)the Key Research and Development Programme of Yunnan(202203AA080010)as part of the Science and Technology Plan Project of Yunnan Provincial Department of Science and Technology.Support from Swedish STINT(CH 2019-8377 and CH 2020-8767)is also acknowledged.
文摘The Three-River Headwaters(TRH)region in the Tibetan Plateau is vulnerable to climate change;changes in summer(June–August)precipitation have a significant impact on water security and sustainability in both local and downstream areas.However,the changes in summer precipitation of different intensities over the TRH region,along with their influencing factors,remain unclear.In this study,we used observational and ERA5 reanalysis data and employed a precipitation categorization and water vapor budget analysis to quantify the categorized precipitation variations and investigate their possible linkages with the water vapor budget.Our results showed an increasing trend in summer precipitation at a rate of 0.9 per year(p<0.1)during 1979–2020,with a significant dry-to-wet transition in 2002.The category‘very heavy precipitation’(10 mm d−1)contributed 65.1%of the increased summer precipitation,which occurred frequently in the northern TRH region.The dry-to-wet transition was caused by the effects of varied atmospheric circulations in each subregion.Southwesterly water vapor transport through the southern boundary was responsible for the increased net water vapor flux in the western TRH region(158.2%),while southeasterly water vapor transport through the eastern boundary was responsible for the increased net water vapor flux in the central TRH(155.2%)and eastern TRH(229.2%)regions.Therefore,we inferred that the dry-to-wet transition of summer precipitation and the increased‘very heavy precipitation’over the TRH was caused by increased easterly and southerly water vapor transport.
基金This work was funded by the National Natural Science Foundation of China(41331174,41101415,41301366)Collaborative Innovation Center of Geospatial Technology,Collaborative Innovation Center for Major Ecological Security Issues of Jiangxi Province and Monitoring Implementation(JXS-EW-08)+2 种基金Special Fund by Surveying&Mapping and Geoinformation Research in the Public Interest(201512026),863 Program(2012AA12A304,2012AA12A306)Natural Science Foundation of Hubei Province of China(2015CFB331)Special funds of State Key Laboratory for equipment.Thanks to Jiangxi Provincial Institute of Water Science for providing partial data for this paper.
文摘The Soil and Water Assessment Tool(SWAT)model was used to assess the impacts of different land use scenarios on hydrological processes in the Fuhe watershed in Poyang Lake Basin,East China.A total of 12 model parameters were calibrated with observed monthly runoff data for 1982-1988 and validated for 1991-1998 for baseline conditions.The baseline test results of R2 and Nash-Sutcliffe model efficiency(NSE)values ranged between 0.88 and 0.94 across the calibration and validation periods,indicating that SWAT accurately replicated the Fuhe watershed streamflow.Several different land use scenarios were then simulated with the model,focusing on the impacts of land use change on the hydrology of the watershed.The results of hypothetical scenario simulations revealed that surface runoff declined while groundwater recharge and evapotranspiration(ET)increased,as forest land,agriculture land and/or grassland areas increased,as well as when paddy field and urban areas decreased.These results further showed that forest land has a higher capacity to conserve the water as compared to pasture land.The results of the real scenario simulations revealed that urbanization is the strongest contributor to changes in surface runoff,water yield,and ET.Urbanization can be considered as a potential major environmental stressor controlling hydrological components.
基金Research has been supported by the following funds:OTKA(NN 79835)and“Agrárklíma.2”(VKSZ_12-1-2013-0034)EFOP-3.6.2-16-2017-00018 EU-national joint founded research project.This paper was also supported by the János Bolyai Scholarship of the Hungarian Academy of SciencesThe research of Zoltán Gribovszki was supported by the European Union and the State of Hungary,co-financed by the European Social Fund in the framework of TÁMOP 4.2.4.A/2-11-1-2012-0001“National Excellence Program.”The work of KB and PCS was supported by the Postdoctoral Research Programme PD-029/2015 of the Hungarian Academy of Sciences.
文摘Introduction:Forest cover in Hungary has increased from 1.1 to 2.0 million hectares during the last century.The EU(European Union)promotes further afforestation;thus,15,000–18,000 ha are being forested each year,mainly in the Hungarian Great Plain.In terms of species used for afforestation,poplar plantations are preferred over native oak woodlands.The groundwater uptake of trees can be a significant water balance element of forested areas in shallow groundwater environments within the Hungarian Great Plain.Forests can cause water table depressions and subsurface salt accumulation in areas with negative water balance.This study examined the hydrological impact of forest cover in the Hungarian Great Plain.Within the framework of this research,climatic water balance,water table depth and salinity,subsoil layering,tree species and stand age were analysed as influencing factors.This paper compares the effect which an oak forest,a poplar plantation and a pasture have on groundwater uptake and salt accumulation.Results:The water table level was roughly 0.4–0.5 m lower beneath the oak forest and the poplar plantation than it was beneath the pasture.Forest groundwater use was 1.5–2 times higher than that of grassland.Groundwater uptake of oak forest was greater than that of poplar plantation during the monitoring period.Salt accumulation,which shows water use in the longer run,was slightly higher for poplar in deeper layers.Conclusions:The greater amount of groundwater used by trees does not lead to a higher salt uptake as only a slight accumulation of salt was measured beneath the forests.Overall,hybrid poplar was slightly less favourable than native oak when considering salinization effects.However,even greater groundwater uptake by trees over longer timescales could cause more significant salt accumulation under pronounced drought conditions due to climate change.
基金Supported by the National Natural Science Foundation of China(41875058 and 42275013)Weather Nowcasting Project for Teaching and Research Teams of China Meteorological Administration+1 种基金Research Project for Young Talents of China Meteorological Administration Training Centre(2022CMATCQN03)Innovation and Development Program of China Meteorological Administration。
文摘In this paper,synoptic-scale analyses of frontogenesis,moisture budget,and tropospheric diabatic heating are performed to reveal the development and maintenance mechanisms for the extreme heavy rainfall in Henan Province of central China from 19 to 21 July 2021,based on station observations and the ECMWF Reanalysis version 5(ERA5)data.The results demonstrate that owing to the blocking effect of local topography,low-level wind convergence in Henan appeared underneath high-level divergence,conducive to development and maintenance of a midtropospheric low-pressure system saddled by the Asian continental high and the western Pacific subtropical high(WPSH),during the extreme heavy rainfall.In the lower troposphere,frontogenesis occurred in the θ_(se) intensive region,as a result of the divergence and horizontal deformation(which play equally important roles),generating frontal secondary circulation with strong vertical motion favorable to heavy rainfall.Moisture budget analysis reveals that 1)with the continuous strengthening of the easterly wind from the north side of Typhoon In-Fa(2106),strong wind shear and orographic uplift led to abnormally strong convergence of water vapor flux in the boundary layer in Henan;2)there occurred extremely strong net inflow of moisture in the boundary layer from the east.Horizontally,both the apparent heat source and the moisture sink coincided with the area of heavy rainfall;vertically,however,Q_(1)exhibited a single peak with the heating center in the middle and upper troposphere,while large Q_(2)values evenly resided over 850–400 hPa;and Q_(1)(Q_(2))was dominated by vertical(horizontal)transport of potential temperature(moisture).These indicate that the latent heat release from condensation of initial heavy rainfall provided a positive feedback,leading to increasingly heavy precipitation.All these synoptic settings sustained the extreme rainfall process.
基金sponsored by the Natural Science Foundation of China(42175078)the Joint Open Project of KLME&CIC-FEMD,NUIST(KLME202207)+1 种基金Special Program for Innovation and Development of China Meteorological Administration(CXFZ2022J030)the Review and Summary Special Project of China Meteorological Administration(FPZJ2023-163).
文摘Due to their huge socio-economic impacts and complex formation causes,extreme and continuous drought events have become the focus and nodus of research in recent years.In the midsummer(July-August)of 2022,a severe drought event occurred in the whole Yangtze River Basin(YRB),China.During that period,the precipitation in the upper,middle and lower reaches of the YRB dropped over 40%less than the 1961-2021 climatic mean,which had never happened previously.Furthermore,the temperature was the highest during 1961-2022.The record-breaking magnitude of less rainfall and high temperature directly led to the continuous development of this extreme drought event.An atmospheric moisture budget analysis revealed that the YRB midsummer rainfall anomaly was dominated by the anomalous powerful vertical moisture advection,which was derived from the strongest descending motion over the whole YRB in the 2022 midsummer during 1981-2022.The western Pacific subtropical high(WPSH)during the midsummer remained stronger,more westward and lasted longer than the climatic mean.As a result,the whole YRB was controlled by a positive geopotential height centre.Further evidence revealed that the anomalous subtropical zonal flow played a crucial role in inducing the extreme descent over the YRB.Moreover,the anomalous upper-tropospheric easterly flow over the YRB in 2022 is the strongest during 1981-2022,modulating the generation of the unprecedented descent anomaly over the YRB.The likelihood that an integrated connection of severe drought in East Asia and flood in West Asia and northwestern South Asia would increase when the extremely strong easterly anomalies in the upper troposphere emerged and induced descending adiabatic flow on the eastern sides of the Tibetan Plateau.The results of this study can provide scientific insights into the predictability of extreme drought events and provide ways to improve predictions.
