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The Gaza Strip is in a chronic state of water shortage and the coastal aquifer as the only freshwater source is increasingly depleted and polluted, especially by nitrate. Assessment of groundwater vulnerability to pollution is essential for adequate protection and management. In this study, the assessment of the aquifer vulnerability to contamination is derived by applying the DRASTIC procedure, firstly with original default weights and ratings and, secondly, improved by estimating rating values by multiple linear regression of observed log-transformed nitrate concentration in groundwater, with DRASTIC factors extended to land-use. The results are very different because high and low vulnerability areas shift considerably. Subsequently, a geostatistical analysis of the spatial distribution of the nitrate concentration is performed, firstly by ordinary kriging interpolation of the observed nitrate concentration and secondly by regression kriging using DRASTIC factors and land-use as indicators of the spatial variation in nitrate occurrence. These maps differ because the map obtained by regression kriging interpolation shows much more details of environmental factors such as dunes, ridges, soil types and built-up areas that affect the presence of nitrate in groundwater. The results of this study can be used by the Palestinian authorities concerned with sustainable groundwater management in the Gaza Strip.
Moustafa El Baba; Prabin Kayastha; Marijke Huysmans; Florimond De Smedt. Groundwater Vulnerability and Nitrate Contamination Assessment and Mapping Using DRASTIC and Geostatistical Analysis. Water 2020, 12, 2022 .
AMA StyleMoustafa El Baba, Prabin Kayastha, Marijke Huysmans, Florimond De Smedt. Groundwater Vulnerability and Nitrate Contamination Assessment and Mapping Using DRASTIC and Geostatistical Analysis. Water. 2020; 12 (7):2022.
Chicago/Turabian StyleMoustafa El Baba; Prabin Kayastha; Marijke Huysmans; Florimond De Smedt. 2020. "Groundwater Vulnerability and Nitrate Contamination Assessment and Mapping Using DRASTIC and Geostatistical Analysis." Water 12, no. 7: 2022.
Florimond De Smedt. Constant‐Rate Pumping Test in a Leaky Aquifer with Water Release from Storage in the Aquitard. Groundwater 2020, 58, 487 -491.
AMA StyleFlorimond De Smedt. Constant‐Rate Pumping Test in a Leaky Aquifer with Water Release from Storage in the Aquitard. Groundwater. 2020; 58 (4):487-491.
Chicago/Turabian StyleFlorimond De Smedt. 2020. "Constant‐Rate Pumping Test in a Leaky Aquifer with Water Release from Storage in the Aquitard." Groundwater 58, no. 4: 487-491.
The Nubian sandstone aquifer is the only water source for domestic use and irrigation in the Kharga oasis, Egypt. In this study, 46 pumping tests are analyzed to estimate the transmissivity of the aquifer and to derive a spatial distribution map by geostatistical analysis and kriging interpolation. The resulting transmissivity values are log-normally distributed and spatially correlated over a distance of about 20 km. Representative values for the transmissivity are a geometric average of about 400 m2/d and a 95% confidence interval of 100–1475 m2/d. There is no regional trend in the spatial distribution of the transmissivity, but there are local clusters with higher or lower transmissivity values. The error map indicates that the highest prediction accuracy is obtained along the central north-south traffic route along which most agricultural areas and major well sites are located. This study can contribute to a better understanding of the hydraulic properties of the Nubian sandstone aquifer in the Kharga oasis for an effective management strategy.
Mustafa El-Rawy; Florimond De Smedt. Estimation and Mapping of the Transmissivity of the Nubian Sandstone Aquifer in the Kharga Oasis, Egypt. Water 2020, 12, 604 .
AMA StyleMustafa El-Rawy, Florimond De Smedt. Estimation and Mapping of the Transmissivity of the Nubian Sandstone Aquifer in the Kharga Oasis, Egypt. Water. 2020; 12 (2):604.
Chicago/Turabian StyleMustafa El-Rawy; Florimond De Smedt. 2020. "Estimation and Mapping of the Transmissivity of the Nubian Sandstone Aquifer in the Kharga Oasis, Egypt." Water 12, no. 2: 604.
Rainfall-induced landslides form an important natural threat in Vietnam. The purpose of this study is to explore regional landslide susceptibility mapping in the mountainous district of A Luoi in Thua Thien Hue Province, where data on the occurrence and causes of landslides are very limited. Three methods are applied to examine landslide susceptibility: statistical index, logistic regression and certainty factor. Nine causative factors are considered: elevation, slope, geological strata, fault density, geomorphic landforms, weathering crust, land use, distance to rivers and annual precipitation. The reliability of the landslide susceptibility maps is evaluated by a receiver operating characteristic curve and the area under the curve is used to quantify and compare the prediction accuracy of the models. The certainty factor model performs best. This model is optimized by maximizing the difference between the true positive rate and the false positive rate. The optimal model correctly identifies 84% of the observed landslides. The results are verified with a validation test, whereby the model is calibrated with 75% randomly selected observed landslides, while the remaining 25% of the observed landslides are used for validation. The validation test correctly identifies 81% of the observed landslides in the training set and 73% of the observed landslides in the validation set.
Nguyen Thanh Long; Florimond De Smedt. Analysis and Mapping of Rainfall-Induced Landslide Susceptibility in A Luoi District, Thua Thien Hue Province, Vietnam. Water 2018, 11, 51 .
AMA StyleNguyen Thanh Long, Florimond De Smedt. Analysis and Mapping of Rainfall-Induced Landslide Susceptibility in A Luoi District, Thua Thien Hue Province, Vietnam. Water. 2018; 11 (1):51.
Chicago/Turabian StyleNguyen Thanh Long; Florimond De Smedt. 2018. "Analysis and Mapping of Rainfall-Induced Landslide Susceptibility in A Luoi District, Thua Thien Hue Province, Vietnam." Water 11, no. 1: 51.
A double constraint method is proposed to analyze pumping tests in a confined aquifer. An expression for estimation of aquifer transmissivity is derived by minimizing the sum of squared errors in the Darcy equation and a similar expression for estimation of aquifer storativity by minimizing the sum of squared errors in the water balance equation. The feasibility of the method is illustrated by two case studies and the results are compared with classical methods for pumping test analysis. The results indicate that the proposed methodology is accurate, robust, easy to implement and execute, and simpler and less time consuming than classical optimization methods.
Florimond De Smedt; Wouter Zijl; Mustafa El-Rawy. Double Constraint Method for Pumping Test Analysis. Journal of Hydrologic Engineering 2018, 23, 06018003 .
AMA StyleFlorimond De Smedt, Wouter Zijl, Mustafa El-Rawy. Double Constraint Method for Pumping Test Analysis. Journal of Hydrologic Engineering. 2018; 23 (7):06018003.
Chicago/Turabian StyleFlorimond De Smedt; Wouter Zijl; Mustafa El-Rawy. 2018. "Double Constraint Method for Pumping Test Analysis." Journal of Hydrologic Engineering 23, no. 7: 06018003.
This chapter deals with the basic elements of the double constraint methodology (DCM). Since the DCM is an imaging method, while most parameter estimation methods are calibration methods, the difference is introduced in Sect. 3.1 and worked out in much greater depths in Sect. 3.9. Section 3.2 introduces the DCM in its most simple, intuitive form. To avoid presentation of three times the same equation for the three conductivity components in anisotropic media, we introduce the “voxel notation” in Sect. 3.3. Sections 3.4 and 3.5 present the theoretical justifications for the “intuitive DCM” presented in Sect. 3.2, while Sect. 3.6 discusses convergence and termination of the iterations. Section 3.7 presents some different approaches to handling anisotropy. Since the DCM is based on two models—the flux model and the head model—the rules for posing the correct boundary conditions for the two models are dealt with in Sect. 3.8.
Wouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. The Pointwise Double Constraint Methodology. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications 2017, 35 -55.
AMA StyleWouter Zijl, Florimond De Smedt, Mustafa El-Rawy, Okke Batelaan. The Pointwise Double Constraint Methodology. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications. 2017; ():35-55.
Chicago/Turabian StyleWouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. 2017. "The Pointwise Double Constraint Methodology." Tunable Low-Power Low-Noise Amplifier for Healthcare Applications , no. : 35-55.
This chapter deals with an extension of the double constraint methodology to handle clusters of grid volumes, or zones. In each zone, the conductivities in the grid volume are correlated. The equations presented in this chapter exemplify this “zone interaction” for clusters with the same grid block conductivities. The results of a case study with a limited number of zones are summarized.
Wouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. The Zone-Integrated Double Constraint Method. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications 2017, 87 -98.
AMA StyleWouter Zijl, Florimond De Smedt, Mustafa El-Rawy, Okke Batelaan. The Zone-Integrated Double Constraint Method. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications. 2017; ():87-98.
Chicago/Turabian StyleWouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. 2017. "The Zone-Integrated Double Constraint Method." Tunable Low-Power Low-Noise Amplifier for Healthcare Applications , no. : 87-98.
This chapter deals with a realistic case study in which a time series of conductivity observations by the double constraint methodology (DCM) is combined with the Kalman filter to determine the observation uncertainty from the spread of the observation noise.
Wouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. Case Study Kleine Nete: Observation Error and Uncertainty. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications 2017, 75 -86.
AMA StyleWouter Zijl, Florimond De Smedt, Mustafa El-Rawy, Okke Batelaan. Case Study Kleine Nete: Observation Error and Uncertainty. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications. 2017; ():75-86.
Chicago/Turabian StyleWouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. 2017. "Case Study Kleine Nete: Observation Error and Uncertainty." Tunable Low-Power Low-Noise Amplifier for Healthcare Applications , no. : 75-86.
This chapter summarizes the double constraint methodology for the estimation of the heterogeneous conductivity fields for groundwater flow modeling. Also, the combination of the double constraint methodology with the Kalman filter to determine the uncertainty of the estimated conductivities is summarized.
Wouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. Summary and Conclusions. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications 2017, 99 -101.
AMA StyleWouter Zijl, Florimond De Smedt, Mustafa El-Rawy, Okke Batelaan. Summary and Conclusions. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications. 2017; ():99-101.
Chicago/Turabian StyleWouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. 2017. "Summary and Conclusions." Tunable Low-Power Low-Noise Amplifier for Healthcare Applications , no. : 99-101.
This chapter deals with the basic equation governing groundwater flow. In Sect. 2.1, the equations are presented in their full four-dimensional form (three spatial dimensions + time) with emphasis on the parameters. Section 2.2 introduces Calderón’s approach to determination of the spatially heterogeneous hydraulic conductivity field. To avoid negative hydraulic conductivities in the double constraint methodology (DCM), this approach is based on the square root of the hydraulic conductivity (sqrt-conductivity α). Section 2.3 introduces Stefanescu’s α-center method for parameter estimation, while Sect. 2.4 analyzes Calderón’s approach in more depth using inspiration from Stefanesco’s method. Although this chapter sets the scene for the real subject matter of this book—the double constraint methodology (DCM)—its reading may be skipped by readers who want to go directly to the DCM treated in Chap. 3.
Wouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. Foundations of Forward and Inverse Groundwater Flow Models. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications 2017, 15 -33.
AMA StyleWouter Zijl, Florimond De Smedt, Mustafa El-Rawy, Okke Batelaan. Foundations of Forward and Inverse Groundwater Flow Models. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications. 2017; ():15-33.
Chicago/Turabian StyleWouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. 2017. "Foundations of Forward and Inverse Groundwater Flow Models." Tunable Low-Power Low-Noise Amplifier for Healthcare Applications , no. : 15-33.
This chapter introduces the subject matter: parameter estimation for groundwater flow models by the double constraint methodology (DCM). After a brief introduction of forward and inverse modeling, the difference between imaging and calibration is mentioned. Some relevant literature is reviewed, and the contents of the chapters of this book are presented.
Wouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. Introduction: Setting the Scene. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications 2017, 1 -14.
AMA StyleWouter Zijl, Florimond De Smedt, Mustafa El-Rawy, Okke Batelaan. Introduction: Setting the Scene. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications. 2017; ():1-14.
Chicago/Turabian StyleWouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. 2017. "Introduction: Setting the Scene." Tunable Low-Power Low-Noise Amplifier for Healthcare Applications , no. : 1-14.
Agricultural expansion in the Kharga Oasis, in the western desert of Egypt, depends strongly on irrigation. Soil hydraulic conductivity is therefore a key property for reclaiming desert land and planning irrigation schemes. Soil samples collected at 10-m intervals in a 120 m by 120 m plot were analysed for hydraulic conductivity together with 12 other basic physical and chemical soil properties. The resulting data were analysed statistically using Pearson correlation, principal component analysis and linear regression. The hydraulic conductivity values varied over four orders of magnitude and, because of the saline–sodic nature of the soil, were about two orders of magnitude smaller than what is generally reported in the literature for similar soil textures. Results showed that the hydraulic conductivity was correlated significantly with soil variables that relate to soil structure, such as wilting point, field capacity and SAR, and less to variables that relate to soil texture, such as silt and clay fractions. Pedotransfer functions for hydraulic conductivity were derived by stepwise multiple linear regression and fitted by residual maximum likelihood. The first model was based directly on soil properties, whereas the second model was based on principal components. Both models showed that part of the variation in hydraulic conductivity encountered in the field could be explained, but with large uncertainty probably resulting from sampling and measurement errors, randomness and soil heterogeneity, or other soil properties that were not observed. The most significant predictors for the first model were wilting point, SAR and silt fraction. The second model used the first two principal components of the soil variables as predictors, the first one related to soil structure and the second to soil texture.
R. Gamie; F. De Smedt. Experimental and statistical study of saturated hydraulic conductivity and relations with other soil properties of a desert soil. European Journal of Soil Science 2017, 69, 256 -264.
AMA StyleR. Gamie, F. De Smedt. Experimental and statistical study of saturated hydraulic conductivity and relations with other soil properties of a desert soil. European Journal of Soil Science. 2017; 69 (2):256-264.
Chicago/Turabian StyleR. Gamie; F. De Smedt. 2017. "Experimental and statistical study of saturated hydraulic conductivity and relations with other soil properties of a desert soil." European Journal of Soil Science 69, no. 2: 256-264.
We start in Sect. 4.1 with the specific storage coefficient and the specific yield, which occur in terms with a time derivative. Next, we deal with flow caused by time-dependent driving mechanisms like recharge and varying pumping well rates. In such cases, we can determine a series of time-dependent parameter estimates, from which the mean value and the standard deviation (the spread of the observation noise) can be determined. According to Bayesian theory on conditional probabilities, the uncertainty in a parameter’s mean value will decrease below the spread with increasing length of the time series. Section 4.2 presents the relevant Kalman filter equations, while Sect. 4.3 presents a comprehensive in-depth explanation. This section also presents calibration by the ensemble Kalman filter (EnKF) with hints how the double constraint methodology (DCM) could be applied to mitigate some disadvantages of the EnKF.
Wouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. Time Dependency. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications 2017, 57 -74.
AMA StyleWouter Zijl, Florimond De Smedt, Mustafa El-Rawy, Okke Batelaan. Time Dependency. Tunable Low-Power Low-Noise Amplifier for Healthcare Applications. 2017; ():57-74.
Chicago/Turabian StyleWouter Zijl; Florimond De Smedt; Mustafa El-Rawy; Okke Batelaan. 2017. "Time Dependency." Tunable Low-Power Low-Noise Amplifier for Healthcare Applications , no. : 57-74.
A combined hydrological and hydraulic model is presented for flood prediction in Vietnam. This model is applied to the Huong river basin as a test case study. Observed flood flows and water surface levels of the 2002–2005 flood seasons are used for model calibration, and those of the 2006–2007 flood seasons are used for validation of the model. The physically based distributed hydrologic model WetSpa is used for predicting the generation and propagation of flood flows in the mountainous upper sub-basins, and proves to predict flood flows accurately. The Hydrologic Engineering Center River Analysis System (HEC-RAS) hydraulic model is applied to simulate flood flows and inundation levels in the downstream floodplain, and also proves to predict water levels accurately. The predicted water profiles are used for mapping of inundations in the floodplain. The model may be useful in developing flood forecasting and early warning systems to mitigate losses due to flooding in Vietnam.
Dang Thanh Mai; Florimond De Smedt. A Combined Hydrological and Hydraulic Model for Flood Prediction in Vietnam Applied to the Huong River Basin as a Test Case Study. Water 2017, 9, 879 .
AMA StyleDang Thanh Mai, Florimond De Smedt. A Combined Hydrological and Hydraulic Model for Flood Prediction in Vietnam Applied to the Huong River Basin as a Test Case Study. Water. 2017; 9 (11):879.
Chicago/Turabian StyleDang Thanh Mai; Florimond De Smedt. 2017. "A Combined Hydrological and Hydraulic Model for Flood Prediction in Vietnam Applied to the Huong River Basin as a Test Case Study." Water 9, no. 11: 879.
Florimond De Smedt; Wouter Zijl. Hydraulic Approach to Groundwater Flow. Two- and Three-Dimensional Flow of Groundwater 2017, 29 -42.
AMA StyleFlorimond De Smedt, Wouter Zijl. Hydraulic Approach to Groundwater Flow. Two- and Three-Dimensional Flow of Groundwater. 2017; ():29-42.
Chicago/Turabian StyleFlorimond De Smedt; Wouter Zijl. 2017. "Hydraulic Approach to Groundwater Flow." Two- and Three-Dimensional Flow of Groundwater , no. : 29-42.
Florimond De Smedt; Wouter Zijl. Fundamentals. Two- and Three-Dimensional Flow of Groundwater 2017, 1 -13.
AMA StyleFlorimond De Smedt, Wouter Zijl. Fundamentals. Two- and Three-Dimensional Flow of Groundwater. 2017; ():1-13.
Chicago/Turabian StyleFlorimond De Smedt; Wouter Zijl. 2017. "Fundamentals." Two- and Three-Dimensional Flow of Groundwater , no. : 1-13.
Florimond De Smedt; Wouter Zijl. Two- and Three-Dimensional Flow of Groundwater. Two- and Three-Dimensional Flow of Groundwater 2017, 1 .
AMA StyleFlorimond De Smedt, Wouter Zijl. Two- and Three-Dimensional Flow of Groundwater. Two- and Three-Dimensional Flow of Groundwater. 2017; ():1.
Chicago/Turabian StyleFlorimond De Smedt; Wouter Zijl. 2017. "Two- and Three-Dimensional Flow of Groundwater." Two- and Three-Dimensional Flow of Groundwater , no. : 1.
Florimond De Smedt; Wouter Zijl. Groundwater Flow Equations. Two- and Three-Dimensional Flow of Groundwater 2017, 15 -27.
AMA StyleFlorimond De Smedt, Wouter Zijl. Groundwater Flow Equations. Two- and Three-Dimensional Flow of Groundwater. 2017; ():15-27.
Chicago/Turabian StyleFlorimond De Smedt; Wouter Zijl. 2017. "Groundwater Flow Equations." Two- and Three-Dimensional Flow of Groundwater , no. : 15-27.
Florimond De Smedt; Wouter Zijl. Examples of Solutions. Two- and Three-Dimensional Flow of Groundwater 2017, 43 -55.
AMA StyleFlorimond De Smedt, Wouter Zijl. Examples of Solutions. Two- and Three-Dimensional Flow of Groundwater. 2017; ():43-55.
Chicago/Turabian StyleFlorimond De Smedt; Wouter Zijl. 2017. "Examples of Solutions." Two- and Three-Dimensional Flow of Groundwater , no. : 43-55.
Tesfamichael Gebreyohannes; Florimond De Smedt; Kristine Walraevens; Solomon Gebresilassie; Abdelwassie Hussien; Miruts Hagos; Kassa Amare; Jozef Deckers; Kindeya Gebrehiwot. Regional groundwater flow modeling of the Geba basin, northern Ethiopia. Hydrogeology Journal 2017, 25, 639 -655.
AMA StyleTesfamichael Gebreyohannes, Florimond De Smedt, Kristine Walraevens, Solomon Gebresilassie, Abdelwassie Hussien, Miruts Hagos, Kassa Amare, Jozef Deckers, Kindeya Gebrehiwot. Regional groundwater flow modeling of the Geba basin, northern Ethiopia. Hydrogeology Journal. 2017; 25 (3):639-655.
Chicago/Turabian StyleTesfamichael Gebreyohannes; Florimond De Smedt; Kristine Walraevens; Solomon Gebresilassie; Abdelwassie Hussien; Miruts Hagos; Kassa Amare; Jozef Deckers; Kindeya Gebrehiwot. 2017. "Regional groundwater flow modeling of the Geba basin, northern Ethiopia." Hydrogeology Journal 25, no. 3: 639-655.