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31.
Evaluation of gene expression programming approaches for estimating daily evaporation through spatial and temporal data scanning 总被引：1，自引：0，他引：1 
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下载免费PDF全文 Evaporation of water from free water surfaces or from land surfaces is one of the main components of the hydrological cycle, and its occurrence is governed by various meteorological and physical factors. There is a multitude of models developed for estimating daily evaporation values by using weather data. This paper evaluates a Gene Expression Programming (GEP) model for estimating evaporation through spatial and temporal data scanning techniques. It is by using ‘leave‐one‐out’ procedures, a complete scan of the possible train and test set configurations is carried out according to temporal and spatial criteria. Comparison of the GEP model with empirical‐physical models shows that daily evaporation values computed by the GEP model are more accurate. Further, local calibration of the GEP model may not be needed, if enough climatic data are available at other stations. The performance of the GEP model fluctuates throughout the period of study and between stations. A suitable assessment of the model should consider a complete temporal and/or spatial scan of the data set used. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
32.
Jalal Ferahtia Kamel Baddari Nouredine Djarfour Abdel Kader Kassouri 《Pure and Applied Geophysics》2010,167(11):1389-1404
Seismic noise is a fundamental part of seismic data which cannot be avoided when conducting any seismic survey. It consists
of coherent and random noise. Noise removal or filtering is one of the major concerns in the field of seismic processing.
In this paper, we introduce an image filtering technique based on a detection-estimation algorithm for Gaussian and random
noise removal in seismic data, namely the trilateral filter, based on a statistic called rank-ordered absolute differences.
The non-linear and adaptive behaviour of this filter makes it very robust in the presence of random and coherent noise, in
addition to its computational simplicity and its ability to automatically identify noise in data. We have modified the strategy
of trilateral filtering by adapting the rank-ordered absolute differences formula in order to extract the signal component.
We have successfully used this filter for the removal of surface waves and random spiky noise from synthetic and field data.
Results are very encouraging and show the superiority of this filter compared with other filters, particularly when used recursively. 相似文献
33.
Nour-Eddine Laftouhi Marnik Vanclooster Mohammed Jalal Omar Witam Mohamed Aboufirassi Mohamed Bahir Étienne Persoons 《Comptes Rendus Geoscience》2003,335(3):307-317
The Essaouira Basin (Morocco) contains a multi-layered aquifer situated in fractured and karstic materials from the Middle and Upper Cretaceous (the Cenomanian, Turonian and Senonian). Water percolates through the limestone and dolomite formations of the Turonian stage either through the marls and calcareous marls of the Cenomanian or through the calcareous marly materials of the Senonian. The aquifer system may be interconnected since the marl layer separating the Turonian, Cenomanian and Senonian aquifers is thin or intensively fractured. In that case, the water is transported through a network of fractures and stratification joints. This paper describes the extent of the nitrate pollution in the area and its origin. Most of the wells and drillholes located in the Kourimat perimeter are contaminated by nitrates with some concentrations over . Nitrate contamination is also observed in the surface water of the Qsob River, which constitutes the natural outlet of the multi-layered complex aquifer system. In this area, agriculture is more developed than in the rest of the Essaouira Basin. Diffuse pollution of the karstic groundwater body by agricultural fertiliser residues may therefore partially explain the observed nitrate pollution. However, point pollution around the wells, springs and drillholes from human wastewater, livestock faeces and the mineralisation of organic debris close to the Muslim cemeteries cannot be excluded. 相似文献
34.
M. Jalal B. Blavoux M. Bahir Y. Bellion N.E. Laftouhi J.M. Puig A. Mennani M. Daniel 《Journal of African Earth Sciences》2001,32(4):1043
In the Meskala-Kourimat area, the Bouabout Syncline aquifer system, intersected by the Igrounzar Wadi, feeds most of the karstic sources of the region. This aquifer is contained within Cenomanian and Turonian limestones and dolomitic limestones. The base of the system corresponds to the lower Cenomanian grey clays, and the top to the Senonian white marls. Hydrodynamic studies of various springs shows that each water source is different from the other, indicating a heterogeneous underground reservoir belonging to a complex karst system. The springs waters show a large chemical variability in space and time. These waters are a mixture of chloride, sulphate, Na and Mg. High Mg contents of some springs result from dissolution of evaporite, confirmed by low Ca/Mg ratios. The total dissolved solids (TDS) in spring water increases from upstream to downstream, probably as a response to residency time, but also due to interaction with Cenomanian evaporites. However, the springs are good for drinking water, as well as for irrigation. The monthly survey of selected springs indicated a large chemical variability but with little or no correlation between discharge and TDS.Stable isotope data (18O) suggests that the altitude of the recharge area, for this aquifer system, is 1200 m. The 18O gradient versus altitude, established on springs whose recharge areas are well known is, −0.25% versus SMOW/100 m. When compared with the ‘Meteoric Water Line’ established on worldwide spring water whose recharge areas are well known, the Essaouira Basin shows rain recharge without any significant evaporation. 相似文献
35.
AbstractAccurate prediction of daily pan evaporation (PE) is important for monitoring, surveying, and management of water resources as well as reservoir management and evaluation of drinking water supply systems. This study develops and applies soft computing models to predict daily PE in a dry climate region of south-western Iran. Three soft computing models, namely the multilayer perceptron-neural networks model (MLP-NNM), Kohonen self-organizing feature maps-neural networks model (KSOFM-NNM), and gene expression programming (GEP), were considered. Daily PE was predicted at two stations using temperature-based, radiation-based, and sunshine duration-based input combinations. The results obtained by the temperature-based 3 (TEM3) model produced the best results for both stations. The Mann-Whitney U test was employed to compute the rank of different input combination for hypothesis testing. Comparison between the soft computing models and multiple linear regression model (MLRM) demonstrated the superiority of MLP-NNM, KSOFM-NNM, and GEP over MLRM. It was concluded that the soft computing models can be successfully employed for predicting daily PE in south western Iran.
Editor D. Koutsoyiannis 相似文献
36.
In arid and semiarid areas, the only surface and groundwater recharge source is the runoff generated through flash floods. Lack of hydrological data in such areas makes runoff estimation extremely complicated. Flash floods are considered catastrophic phenomena posing a major hazardous threat to cities, villages, and their infrastructures. The objective of this study is to assess the flash flood hazard and runoff in Wadi Halyah and its sub-basins. Integration of morphometric parameters, geo-informatics, and hydrological models has been done to overcome the challenge of scarcity of data.Advanced Spaceborne Thermal Emission and Reflection (ASTER) data was used to prepare a digital elevation model (DEM) with 30-m resolution, and geographical information system (GIS) was used in the evaluation of network, geometry, texture, and relief features of the morphometric parameters. Thirty-eight morphometric parameters were estimated and have been linked together for producing nine effective parameters for evaluation of the flash flood hazard in the study basin.Flash flood hazard in Wadi Halyah and its sub-basins was identified and grouped into three classes depending on nine effective parameters directly influencing the flood prone areas. Calculated runoff volume of Wadi Halyah ranges from 26.7 × 106 to 111.4 × 106 m3 with an inundation area of 15 and 27 km2 at return periods of 5 and 100 years, respectively. Mathematical relationships among rainfall depth, runoff volume, infiltration losses, and rainfall excess demonstrate a strong directly proportional relationships with correlation coefficient of about 0.99. 相似文献