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Theoretical and Applied Climatology - Precipitation as the main process that brings evaporated water from the oceans to the land’s surface is a critical role player in Lake Urmia basin... 相似文献
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AbstractMathematical models developed for quantification of sediment transport in hydrological watersheds require data collected through field or laboratory experiments, but these are still very rare in the literature. This study aims to collect such data at the laboratory scale. To this end, a rainfall simulator equipped with nozzles to spray rainfall was constructed, together with an erosion flume that can be given longitudinal and lateral slopes. Eighty experiments were performed, considering microtopographical features by pre-forming a rill on the soil surface before the start of each experiment. Medium and fine sands were used as soil, and four rainfall intensities (45, 65, 85 and 105 mm h-1) were applied in the experiments. Rainfall characteristics such as uniformity, granulometry, drop velocity and kinetic energy were evaluated; flow and sediment discharge data were collected and analysed. The analysis shows that the sediment transport rate is directly proportional to rainfall intensity and slope. In contrast, the volumetric sediment concentration stays constant and does not change with rainfall intensity unless the slope changes. These conclusions are restricted to the conditions of experiments performed under rainfall intensities between and 105 mm h-1 for medium and fine sands in a 136-cm-wide, 650-cm-long and 17-cm-deep erosion flume with longitudinal and lateral slopes varying between 5 and 20%.Editor Z.W. Kundzewicz; Associate editor G. MahéCitation Aksoy, H., Unal, N.E., Cokgor, S., Gedikli, A., Yoon, J., Koca, K., Inci, S.B., Eris, E., and Pak, G., 2013. Laboratory experiments of sediment transport from bare soil with a rill. Hydrological Sciences Journal, 58 (7), 1505–1518. 相似文献
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Segmentation algorithm for long time series analysis 总被引:2,自引:2,他引:0
Abdullah Gedikli Hafzullah Aksoy N. Erdem Unal 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(3):291-302
Time series analysis is an important issue in the earth science-related engineering applications such as hydrology, meteorology
and environmetrics. Inconsistency and nonhomogeneity that might arise in a time series yield segments with different statistical
characteristics. In this study, an algorithm based on the first order statistical moment (average) of a time series is developed
and applied on five time series with length ranging from 84 items to nearly 1,300. Comparison to the existing segmentation
algorithms proves the applicability and usefulness of the proposed algorithm in long hydrometeorological and geophysical time
series analysis. 相似文献
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Being a large hyper‐saline water body, Lake Urmia in north‐western Iran deals with a gradual decline in its water level. Most of the studies on Lake Urmia have neglected the groundwater issue. In this study, as a direct approach, the interaction between the groundwater level and the lake water level is investigated both in time and space by analysing the groundwater data compiled from observation wells surrounding the lake. Baseflow separation is considered as an indirect approach to understand the groundwater contribution to the river network flowing into the lake. It is determined that about 70% of run‐off in the rivers draining into the lake is born in the form of baseflow. An interaction between the lake and the groundwater storage is clearly seen from the analysis to conclude that groundwater has a potential to recharge the lake. Thus, the shrinkage of water level in Lake Urmia could be expected to accelerate with the drastic use of groundwater, which will be a disaster with no return. 相似文献
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The United Kingdom Institute of Hydrology (UKIH) smoothed minima baseflow separation method originally developed for the daily flow data of perennial streams and adopted for intermittent streams is presented. The adopted method (AdUKIH) is the generalized version of the UKIH and hence applicable not only to intermittent streams but also to perennial streams. The AdUKIH method is applied on three daily streamflow gauging stations from the European part of Turkey, the Thrace region. The AdUKIH enables one to change the parameter 0·9 in the UKIH method and also introduces different block sizes, which is limited to five days in the original UKIH method. The AdUKIH method is considered a useful tool in helping practitioners and researchers to separate continuous baseflow from the daily flow in perennial and intermittent streams. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Modified dynamic programming approach for offline segmentation of long hydrometeorological time series 总被引:3,自引:1,他引:2
Abdullah Gedikli Hafzullah Aksoy N. Erdem Unal Athanasios Kehagias 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(5):547-557
For the offline segmentation of long hydrometeological time series, a new algorithm which combines the dynamic programming with the recently introduced remaining cost concept of branch-and-bound approach is developed. The algorithm is called modified dynamic programming (mDP) and segments the time series based on the first-order statistical moment. Experiments are performed to test the algorithm
on both real world and artificial time series comprising of hundreds or even thousands of terms. The experiments show that
the mDP algorithm produces accurate segmentations in much shorter time than previously proposed segmentation algorithms. 相似文献
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Hafzullah Aksoy Ahmad Dahamsheh 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(7):917-931
Forecasting precipitation in arid and semi-arid regions, in Jordan in the Middle East for example, has particular importance
since precipitation is the unique source of water in such regions. In this study, 1-month ahead precipitation forecasts are
made using artificial neural network (ANN) models. Feed forward back propagation (FFBP), radial basis function (RBF) and generalized
regression type ANNs are used and compared with a simple multiple linear regression (MLR) model. The models are tested on
monthly total precipitation recorded at three meteorological stations (Baqura, Amman and Safawi) from different climatological
regions in Jordan. For the three stations, it is found that the best calibrated model is FFBP with respect to all performance
criteria used in the study, including determination coefficient, mean square error, mean absolute error, the slope and the
intercept in the best-fit linear line of the scatter diagram. In the validation stage, FFBP is again the best model in Baqura
and Amman. However, in Safawi, the driest station, not only FFBP but also RBF and MLR perform equally well depending on the
performance criterion under consideration. 相似文献