共查询到20条相似文献，搜索用时 15 毫秒
1.
HANS-JURGEN LIEBSCHER 《水文科学杂志》2013,58(2):283-296
Abstract Evaporation in the Upper Harz experimental basins is computed and compared to the values calculated according to formulae. Potential evaporation is determined for mean daily and monthly values by different methods. For the computation of the terms generally lacking in water balance studies, such as actual evaporation and changes in snow and soil storage, a model was established on the basis of daily values. As a result water balances can also be drawn up for shorter periods such as single years or months. 相似文献
2.
The Special Sensor Microwave/Imager (SSM/I) radiometer is a useful tool for monitoring snow wetness on a large scale because water content has a significant effect on the microwave emissions at the snowpack surface. To date, SSM/I snow wetness algorithms, based on statistical regression analysis, have been developed only for specific regions. Inadequate ground-based snow wetness measurements and the non-linearity between SSM/I brightness temperatures (TBs) and snow wetness over varied vegetation covered terrain has impeded the development of a general model. In this study, we used a previously developed linear relationship between snowpack surface wetness (% by volume) and concurrent air temperature (°C) to estimate the snow wetness at ground weather stations. The snow condition (snow free, dry, wet or refrozen snow) of each SSM/I pixel (a 37 × 29 km area at 37.0 GHz) was determined from ground-measured weather data and the TB signature. SSM/I TBs of wet snow were then linked with the snow wetness estimates as an input/output relationship. A single-hidden-layer back-propagation (backprop) artificial neural network (ANN) was designed to learn the relationships. After training, the snow wetness values estimated by the ANN were compared with those derived by regression models. Results show that the ANN performed better than the existing regression models in estimating snow wetness from SSM/I data over terrain with different amounts of vegetation cover. 相似文献
3.
Adrian A. Harpold Noah P. Molotch Keith N. Musselman Roger C. Bales Peter B. Kirchner Marcy Litvak Paul D. Brooks 《水文研究》2015,29(12):2782-2798
Western US forest ecosystems and downstream water supplies are reliant on seasonal snowmelt. Complex feedbacks govern forest–snow interactions in which forests influence the distribution of snow and the timing of snowmelt but are also sensitive to snow water availability. Notwithstanding, few studies have investigated the influence of forest structure on snow distribution, snowmelt and soil moisture response. Using a multi‐year record from co‐located observations of snow depth and soil moisture, we evaluated the influence of forest‐canopy position on snow accumulation and snow depth depletion, and associated controls on the timing of soil moisture response at Boulder Creek, Colorado, Jemez River Basin, New Mexico, and the Wolverton Basin, California. Forest‐canopy controls on snow accumulation led to 12–42 cm greater peak snow depths in open versus under‐canopy positions. Differences in accumulation and melt across sites resulted in earlier snow disappearance in open positions at Jemez and earlier snow disappearance in under‐canopy positions at Boulder and Wolverton sites. Irrespective of net snow accumulation, we found that peak annual soil moisture was nearly synchronous with the date of snow disappearance at all sites with an average deviation of 12, 3 and 22 days at Jemez, Boulder and Wolverton sites, respectively. Interestingly, sites in the Sierra Nevada showed peak soil moisture prior to snow disappearance at both our intensive study site and the nearby snow telemetry stations. Our results imply that the duration of soil water stress may increase as regional warming or forest disturbance lead to earlier snow disappearance and soil moisture recession in subalpine forests. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
4.
Shuko Hamada Takeshi Ohta Tetsuya Hiyama Takashi Kuwada Atsuhiro Takahashi Trofim C. Maximov 《水文研究》2004,18(1):23-39
Seasonal changes in the water and energy exchanges over a pine forest in eastern Siberia were investigated and compared with published data from a nearby larch forest. Continuous observations (April to August 2000) were made of the eddy‐correlation sensible heat flux and latent heat flux above the canopy. The energy balance was almost closed, although the sum of the turbulent fluxes sometimes exceeded the available energy flux (Rn ? G) when the latent heat flux was large; this was related to the wind direction. We examined the seasonal variation in energy balance components at this site. The seasonal variation and magnitude of the sensible heat flux (H) was similar to that of the latent heat flux (λE), with maximum values occurring in mid‐June. Consequently, the Bowen ratio was around 1·0 on many days during the study period. On some clear days just after rainfall, λE was very large and the sum of H and λE exceeded Rn ? G. The evapotranspiration rate above the dry canopy from May to August was 2·2 mm day?1. The contributions of understory evapotranspiration (Eu) and overstory transpiration (Eo) to the evapotranspiration of the entire ecosystem (Et) were both from 25 to 50% throughout the period analysed. These results suggest that Eu plays a very important role in the water cycle at this site. From snowmelt through the tree growth season (23 April to 19 August 2000), the total incoming water, comprised of the sum of precipitation and the water equivalent of the snow at the beginning of the melt season, was 228 mm. Total evapotranspiration from the forest, including interception loss and evaporation from the soil when the canopy was wet, was 208–254 mm. The difference between the incoming and outgoing amounts in the water balance was from +20 to ?26 mm. The water and energy exchanges of the pine and larch forest differed in that λE and H increased slowly in the pine forest, whereas λE increased rapidly in the larch forest and H decreased sharply after the melting season. Consequently, the shape of the Bowen ratio curves at the two sites differed over the period analysed, as a result of the differences in the species in each forest and in soil thawing. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
5.
6.
A. Sugimoto D. Naito N. Yanagisawa K. Ichiyanagi N. Kurita J. Kubota T. Kotake T. Ohata T. C. Maximov A. N. Fedorov 《水文研究》2003,17(6):1073-1092
Soil moisture and its isotopic composition were observed at Spasskaya Pad experimental forest near Yakutsk, Russia, during summer in 1998, 1999, and 2000. The amount of soil water (plus ice) was estimated from volumetric soil water content obtained with time domain reflectometry. Soil moisture and its δ18O showed large interannual variation depending on the amount of summer rainfall. The soil water δ18O decreased with soil moisture during a dry summer (1998), indicating that ice meltwater from a deeper soil layer was transported upward. On the other hand, during a wet summer (1999), the δ18O of soil water increased due to percolation of summer rain with high δ18O values. Infiltration after spring snowmelt can be traced down to 15 cm by the increase in the amount of soil water and decrease in the δ18O because of the low δ18O of deposited snow. About half of the snow water equivalent (about 50 mm) recharged the surface soil. The pulse of the snow meltwater was, however, less important than the amount of summer rainfall for intra‐annual variation of soil moisture. Excess water at the time just before soil freezing, which is controlled by the amount of summer rainfall, was stored as ice during winter. This water storage stabilizes the rate of evapotranspiration. Soil water stored in the upper part of the active layer (surface to about 120 cm) can be a water source for transpiration in the following summer. On the other hand, once water was stored in the lower part of the active layer (deeper than about 120 cm), it would not be used by plants in the following summer, because the lower part of the active layer thaws in late summer after the plant growing season is over. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
7.
Vassilis Z. Antonopoulos Soultana K. Gianniou Athanasios V. Antonopoulos 《水文科学杂志》2013,58(14):2590-2599
ABSTRACTEvaporation is one of the most important components in the energy and water budgets of lakes and is a primary process of water loss from their surfaces. An artificial neural network (ANN) technique is used in this study to estimate daily evaporation from Lake Vegoritis in northern Greece and is compared with the classical empirical methods of Penman, Priestley-Taylor and the mass transfer method. Estimation of the evaporation over the lake is based on the energy budget method in combination with a mathematical model of water temperature distribution in the lake. Daily datasets of air temperature, relative humidity, wind velocity, sunshine hours and evaporation are used for training and testing of ANN models. Several input combinations and different ANN architectures are tested to detect the most suitable model for predicting lake evaporation. The best structure obtained for the ANN evaporation model is 4-4-1, with root mean square error (RMSE) from 0.69 to 1.35 mm d?1 and correlation coefficient from 0.79 to 0.92.
EDITOR M.C. AcremanASSOCIATE EDITOR not assigned 相似文献
8.
When evaporation from the surfaces of a region is limited by the availability of moisture the resultant changes in the temperature and humidity of the overpassing air are reflected in the potential evaporation. Such interactions have provided the basis for the progressive development of a model in which the regional evaporation, a product of climatic, soil moisture and vegetative processes, is estimated from its effects on potential evaporation or on representative climatological observations. Further improvements are presented and the results are tested with previously published hydrologic and climatologic data from twenty river catchments in Canada and Ireland. These catchments have a range in annual runoff of approximately zero to one meter and a range of snow cover duration from almost zero to six months. Comparison of model predictions with precipitation less runoff estimates for five year periods provides reasonable evidence for the validity of the model with a maximum deviation of 44 mm yr−1, or 9%, and a standard error of estimate of 26 mm yr−1. Seasonal comparisons permit insights into the variability of catchment storage and the effects of climate and topograpy on regional evaporation. 相似文献
9.
Abstract Long term research has been conducted into the hydrological effects of different land usage of a wetland mire in southern Germany. Drainage for agriculture lowered the water table and reduced evaporation from about 110% of open water losses to just under the Penman short grass potential rate. The runoff regime was altered and peak flows increased. Afforestation of agricultural land increased evaporation losses to much higher levels than open water evaporation, and annual runoff was nearly halved. Forest growth reduced soil water and baseflows. Peak flows became smaller; the rate of reduction was particularly rapid in the early years of tree growth. 相似文献
10.
Observation and estimation of evaporation from the ground surface of the cryosphere in eastern Asia 总被引：1，自引：0，他引：1
The characteristics of evaporation from the ground surface of Asian cryosphere sites are presented, as estimated by the lysimeter method, a profile method, and a heat budget method. The observation sites were located on the eastern Tibetan Plateau, in the Qilian and Tianshan Mountains of China, and in eastern Siberia. The lysimeter method has been demonstrated to be a reliable observation technique for estimating daily evaporation from the land surface, given suitable experiment design and operation. Daily mean evaporation varied within the range of 0·3 to 3·5 mm on the permafrost surface, and regional differences in evaporation were strongly related to surface soil moisture. Locally, topography, by way of its influence on surface soil moisture, was found to control evaporation systematically. Seasonality of ground evaporation in permafrost regions is dominated by thaw–freeze cycles at the surface; evaporation from the melting permafrost surface is up to four to seven times greater than that from frozen ground. In forested terrain, the interception of precipitation can reduce daily evaporation by 60 to 70%. Sublimation from the snow surface was observed at some sites in the range of 0·2 to 1·0 mm daily; atmospheric conditions, such as wind speed and saturation deficit, were dominant factors in determining snow sublimation. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
11.
《水文科学杂志》2013,58(1):199-209
Abstract The rainfall record from the Durham University Observatory (UK) in the 1870s is examined: this decade was a very wet one nationally, but the Durham totals seem too high. Comparison with data from nearby gauges in northeast England and with a more distant gauge at Edinburgh confirms that this is so. The cause is most likely related to a faulty raingauge in use from January 1872; the problem was apparently rectified by August 1879. Analysis confirms inhomogeneities in the original time series; corrections are applied based on nearby raingauges and a smaller 8-inch gauge in use at the Observatory. In the corrected record, 1872 remains the wettest year at Durham and 1877 ranks fifth. However, the 1870s no longer ranks as the wettest decade, the 1930s and 1960s both being slightly wetter. 相似文献
12.
J. P. BRUCE 《水文科学杂志》2013,58(2):141-150
Abstract The hydrological regime of a mountainous catchment, in this instance the Mesochora catchment in Central Greece, was simulated for altered climates resulting when using the Goddard Institute for Space Studies (GISS) model for carbon dioxide doubling. The catchment snow water equivalent was predicted on the basis of the snow accumulation and ablation model of the US National Weather Service River Forecast System (NWSRFS), while the catchment runoff, as well as actual evapotranspiration and soil moisture storages, were simulated through application of the soil moisture accounting model of NWSRFS. Two scenarios of monthly climate change were drawn from the GISS model, one associated with temperature and precipitation changes, while the other referred to temperature changes alone. A third hypothetical scenario with temperature and precipitation changes similar to those corresponding to the mean monthly GISS scenarios was used to test the sensitivity of the monthly climate change of the hypothetical case on catchment hydrology. All three scenarios projected decreases in average snow accumulations and in spring and summer runoff and soil moisture, as well as increases in winter runoff and soil moisture storage and spring evapotranspiration. 相似文献
13.
Enrique A. Torres 《水文科学杂志》2013,58(3):303-315
Abstract This study evaluates the evaporation component of the FAO-56 model under high evaporation demand. To perform this, two data sets were used as field evaluation, and a second model was used for comparison (a model based on the square root of time, SRT). The results show that although FAO-56, the field data and the SRT model present similar cumulative evaporation over the study period (approximately one month), when the data are analysed daily, FAO-56 overestimated evaporation at the beginning of the process and underestimated it at the end. A correction for FAO-56 is proposed to amend the mismatch between FAO-56 and the field-measured data under high evaporation conditions. Consequently, the parameters used by the FAO-56 evaporation component are discussed. Citation Torres, E. A. & Calera, A. (2010) Bare soil evaporation under high evaporation demand: a proposed modification to the FAO-56 model. Hydrol. Sci. J. 55(3), 303–315. 相似文献
14.
Alexander C. Brandt Qiqin Zhang Maximo Larry Lopez Caceres Hideki Murayama 《水文研究》2020,34(15):3235-3251
Warm winters and high precipitation in north-eastern Japan generate snow covers of more than three meters depth and densities of up to 0.55 g cm−3. Under these conditions, rain/snow ratio and snowmelt have increased significantly in the last decade under increasing warm winters. This study aims at understanding the effect of rain-on-snow and snowmelt on soil moisture under thick snow covers in mid-winter, taking into account that snowmelt in spring is an important source of water for forests and agriculture. The study combines three components of the Hydrosphere (precipitation, snow cover and soil moisture) in order to trace water mobility in winter, since soil temperatures remained positive in winter at nearly 0.3°C. The results showed that soil moisture increased after snowmelt and especially after rain-on-snow events in mid-winter 2018/2019. Rain-on-snow events were firstly buffered by fresh snow, increasing the snow water equivalent (SWE), followed by water soil infiltration once the water storage capacity of the snowpack was reached. The largest increase of soil moisture was 2.35 vol%. Early snowmelt increased soil moisture with rates between 0.02 and 0.035 vol% hr−1 while, rain-on-snow events infiltrated snow and soil faster than snowmelt and resulted in rates of up to 1.06 vol% hr−1. These results showed the strong connection of rain, snow and soil in winter and introduce possible hydrological scenarios in the forest ecosystems of the heavy snowfall regions of north-eastern Japan. Effects of rain-on-snow events and snowmelt on soil moisture were estimated for the period 2012–2018. Rain/snow ratio showed that only 30% of the total precipitation in the winter season 2011/2012 was rain events while it was 50% for the winter 2018/2019. Increasing climate warming and weakening of the Siberian winter monsoons will probably increase rain/snow ratio and the number of rain-on-snow events in the near future. 相似文献
15.
小时尺度水面蒸发可影响水面大气边界层热力和动力结构,分析湖泊小时尺度水面蒸发主要影响因素,选取准确模拟其特征的蒸发模型,将有助于改善流域天气预报和空气质量预报.基于太湖避风港站2012—2013年通量、辐射和气象观测数据,分析太湖小时尺度水面蒸发主要影响因子和3个模型(传统质量传输模型、Granger and Hedstrom经验模型、DYRESM模型)的模拟效果.结果表明:影响太湖小时尺度水面蒸发的主要因子为水气界面水汽压差和风速的乘积,而非净辐射.传统质量传输模型、Granger and Hedstrom经验模型、DYRESM模型模拟值与全年实测值的一致性系数分别为0.92、0.87和0.89,均方根误差分别为28.35、41.58和38.26 W/m~2.传统质量传输模型对太湖小时尺度水面蒸发的日变化和季节动态模拟效果最佳,其夜间模拟相对误差小于3%,除秋季外,其他季节的模拟绝对误差均小于4 W/m~2.Granger and Hedstrom经验模型系统性地高估太湖潜热通量,在大气较为稳定的午后(高估22~32 W/m~2)和冬季(高估72%)高估最为明显,模拟效果最差.DYRESM模型也系统地高估太湖潜热通量,模拟效果居中.考虑水汽交换系数随风速的变化特征将有助于改善传统质量传输模型和DYRESM模型对太湖小时尺度水面蒸发的模拟精度. 相似文献
16.
J. P. KRIEL 《水文科学杂志》2013,58(4):10-26
Summary Evaporation comparisons for Symon's evaporation tanks (6 feet square and 24 inches deep, sunk into the ground) and American A-type tanks as determined at 34 stations throughout South Africa are discussed. Recently a series of observations to investigate relationships between evaporation from Symon's tanks and that from large water surfaces in South Africa were carried out. The latter varied from 40 acres to 3,200 acres in size, with depths from a few inches to 131 feet. The techniques used in measurement are briefly described and results of the determinations presented. 相似文献
17.
Matthew K. MacDonald Bruce J. Davison Muluneh A. Mekonnen Alain Pietroniro 《水文科学杂志》2013,58(16):2860-2871
ABSTRACTThe low density of meteorological stations in parts of Canada necessitates using numerical weather prediction (NWP)/assimilation output for hydrological modelling. In this study, comparisons are made of simulated land surface variables when using field observations versus NWP output as forcing for two well-instrumented sites: the mountainous and forested Marmot Creek Basin (MCRB) in the Canadian Rocky Mountains, and a prairie cropland/grassland site (Kenaston). The Canadian Land Surface Scheme 3.6 (CLASS) was used for modelling. The Global Environmental Multiscale (GEM) model with Canadian Precipitation Analysis (CaPA) was also used as forcing. There was good agreement between observed meteorology and GEM/CaPA, though some deficiencies in GEM/CaPA were identified: the effects of sub-grid topography on incoming radiation and wind speed were not accounted for at MCRB, and CaPA did not capture some convective rainfall events at Kenaston. CLASS simulations using both sets of forcing showed difficulties in simulating snow depth, soil moisture and evapotranspiration; certain difficulties were linked to GEM/CaPA deficiencies and/or CLASS. Both sets of forcing tended to overestimate the duration of snow cover at MCRB, but during different years. With GEM/CaPA as forcing, CLASS overestimated the duration of frozen soils. The GEM/CaPA precipitation difficulties at Kenaston degraded soil moisture simulations.
EDITOR A. Castellarin; ASSOCIATE EDITOR E. Volpi 相似文献
18.
Abstract The dominant source of streamflow in many mountainous watersheds is snowmelt recharge through shallow groundwater systems. The hydrological response of these watersheds is controlled by basin structure and spatially distributed snowmelt. The purpose of this series of two papers is to simulate spatially varying snowmelt and groundwater response in a small mountainous watershed. This paper examines the spatially and temporally variable snowmelt to be used as input to the groundwater flow modelling described in the second paper. Snowmelt simulation by the Simultaneous Heat and Water (SHAW) model (a detailed process model of the interrelated heat, water and solute movement through vegetative cover, snow, residue and soil) was validated by applying the model to two years of data at three sites ranging from shallow transient snow cover on a west-facing slope to a deep snow drift on a north-facing slope. The simulated energy balances for several melt periods are presented. Snow depth, density, and the magnitude and timing of snow cover outflow were simulated well for all sites. 相似文献
19.
Ian Hers Parisa Jourabchi Matthew A. Lahvis Paul Dahlen E. Hong Luo Paul Johnson George E. DeVaull K. Ulrich Mayer 《Ground Water Monitoring & Remediation》2014,34(4):60-78
A detailed seasonal study of soil vapor intrusion at a cold climate site with average yearly temperature of 1.9 °C was conducted at a house with a crawlspace that overlay a shallow dissolved‐phase petroleum hydrocarbon (gasoline) plume in North Battleford, Saskatchewan, Canada. This research was conducted primarily to assess if winter conditions, including snow/frost cover, and cold soil temperatures, influence aerobic biodegradation of petroleum vapors in soil and the potential for vapor intrusion. Continuous time‐series data for oxygen, pressure differentials, soil temperature, soil moisture, and weather conditions were collected from a high‐resolution monitoring network. Seasonal monitoring of groundwater, soil vapor, crawlspace air, and indoor air was also undertaken. Petroleum hydrocarbon vapor attenuation and biodegradation rates were not significantly reduced during low temperature winter months and there was no evidence for a significant capping effect of snow or frost cover that would limit oxygen ingress from the atmosphere. In the residual light nonaqueous phase liquid (LNAPL) source area adjacent to the house, evidence for biodegradation included rapid attenuation of hydrocarbon vapor concentrations over a vertical interval of approximately 0.9 m, and a corresponding decrease in oxygen to less than 1.5% v/v. In comparison, hydrocarbon vapor concentrations above the dissolved plume and below the house were much lower and decreased sharply within a few tens of centimeters above the groundwater source. Corresponding oxygen concentrations in soil gas were at least 10% v/v. A reactive transport model (MIN3P‐DUSTY) was initially calibrated to data from vertical profiles at the site to obtain biodegradation rates, and then used to simulate the observed soil vapor distribution. The calibrated model indicated that soil vapor transport was dominated by diffusion and aerobic biodegradation, and that crawlspace pressures and soil gas advection had little influence on soil vapor concentrations. 相似文献
20.
Abstract The areal and temporal characteristics of the snowpack in a small subarctic drainage basin at Schefferville, Quebec, were analysed prior to and during the snowmelt in 1972 and 1973. The data showed that vegetation cover is of prime importance in determining the areal distribution of snowpack properties. The areal distribution of snow water equivalent could be characterized by a normal distribution in each of four vegetation cover types. It was found that the mean and standard deviation of snow water equivalent are closely related to vegetation cover. Also, mean snow water equivalent varies from year to year but standard deviation shows no significant variation. This suggests that mean accumulation is the result of annual snowfall amounts, while the variability is due to the effects of vegetation cover and accumulation processes. The data also showed that during the snowmelt, the variability of snowcover properties shows no significant change. Using the normal distributions of the peak accumulation snow water equivalents, and observed and calculated melt rates, the areal extent of snowcover was determined. 相似文献