| 1. |
- Berndtsson, Ronny, et al.
(författare)
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Educating the compassionate water engineer - a remedy to avoid future water management failures?
- 2005
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 50:1, s. 7-16
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Tidskriftsartikel (refereegranskat)abstract
- The number of local and regional-scale water management failures appears steadily to increase despite an apparently higher level of engineering solutions at hand. The objective of this paper is to examine the challenges the existing education system needs to meet in order to produce water engineers capable of responding to the complexity of contemporary and future water problems in relation to societal needs. The next generation of water engineers may stay in their professional functions until 2040 or 2050. It is likely that in this period more critical water management and environmental problems will be experienced than have been encountered so far. The question then arises whether the present water engineers have the proper background education to understand environmental, hydrological, ecological and socio-economic problems to resolve related water management problems. Future water engineers must, to a greater extent, include socio-economic consequences in planned and/or designed water management systems and convey greater transparency regarding risks and societal effects.
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| 2. |
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| 3. |
- Bouksila, Fethi, et al.
(författare)
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Soil water content and salinity determination using different dielectric methods in saline gypsiferous soil
- 2008
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 53:1, s. 253-265
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedMeasurements of dielectric permittivity and electrical conductivity were taken in a saline gypsiferous soil collected from southern Tunisia. Both time domain reflectometry (TDR) and the new WET sensor based on frequency domain reflectometry (FDR) were used. Seven different moistening solutions were used with electrical conductivities of 0.0053-14 dS m(-1). Different models for describing the observed relationships between dielectric permittivity (K-a) and water content (theta), and bulk electrical conductivity (ECa) and pore water electrical conductivity (ECp) were tested and evaluated. The commonly used K-a-theta models by Topp et al. (1980) and Ledieu et al. (1986) cannot be recommended for the WET sensor. With these models, the RMSE and the mean relative error of the predicted theta were about 0.04 m(3) m(-3) and 19% for TDR and 0.08 m(3) m(-3) and 54% for WET sensor measurements, respectively. Using the Hilhorst (2000) model for ECp predictions, the RMSE was 1.16 dS m(-1) and 4.15 dS m(-1) using TDR and the WET sensor, respectively. The WET sensor could give similar accuracy to TDR if calibrated values of the soil parameter were used instead of standard values.
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| 4. |
- Chen, Y. D., et al.
(författare)
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Regional analysis of low flow using L-moments for Dongjiang basin, South China
- 2006
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 51:6, s. 1051-1064
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Tidskriftsartikel (refereegranskat)abstract
- Dongjiang water has been the key source of water supplies for Hong Kong and its neighbouring cities in the Pearl River Delta in South China since the mid-1960s. Rapid economic development and population growth in this region have caused serious concerns over the adequacy of the quantity and quality of water withdrawn from the Dongjiang River in the future. Information on the magnitude and frequency of low flows in the basin is needed for planning of water resources at present and in the near future. The L-moment method is used to analyse the regional frequency of low flows, since recent studies have shown that it is superior to other methods that have been used previously, and is now being adopted by many organizations worldwide. In this study, basin-wide analysis of low flows is conducted for Dongjiang basin using five distributions: generalized logistic, generalized extreme value, lognormal, Pearson type III and generalized Pareto. Each of these has three parameters estimated by the L-moment method. The discordancy index and homogeneity testing show that 14 out of the 16 study sites belong to a homogenous region; these are used for further analysis. Based on the L-moment ratios diagram, the Hosking and Wallis goodness-of-fit statistical criterion and the L-kurtosis criterion, the three-parameter lognormal distribution is identified as the most appropriate distribution for the homogeneous study region. The regional low-flow estimates for each return period are obtained using the index flood procedure. Examination of the observed and simulated low flows by regional frequency analysis shows a good agreement in general, and the results may satisfy practical application. Furthermore, the regional low-flow relationship between mean annual 7-day low flows and basin area is developed using linear regression, providing a simple and effective method for estimation of low flows of desired return periods for ungauged catchments.
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| 5. |
- Di Baldassarre, Giuliano, et al.
(författare)
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Analysis of the effects of levee heightening on flood propagation : example of the River Po, Italy
- 2009
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 54:6, s. 1007-1017
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Tidskriftsartikel (refereegranskat)abstract
- The effects of human activities on flood propagation, during the period 1878-2005, in a 190-km reach of the middle-lower portion of the River Po (Northern Italy) are investigated. A series of topographical, hydrological and inundation data were collected for the 1878 River Po geometry and the June 1879 flood event, characterised by an inundated area of 432 km(2). The aim of the study is two-fold: (1) to show the applicability of flood inundation models in reconstructing historical inundation events, and (2) to assess the effects of human activities during the last century on flood propagation in the middle-lower portion of the River Po. Numerical simulations were performed by coupling a two-dimensional finite element code, TELEMAC-2D, with a one-dimensional finite difference code, HEC-RAS.
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| 6. |
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| 7. |
- Hamed Abd El Mageed, Yasser, et al.
(författare)
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Evaluation of the WET sensor compared to time domain reflectometry
- 2006
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 51:4, s. 671-681
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Tidskriftsartikel (refereegranskat)abstract
- This paper concentrates on the experimental calibration of a rapid, non-destructive sensor to investigate the salinization process by measuring the dielectric properties of the soil to estimate both the soil water content (theta) and pore water electrical conductivity (sigma(p)) for different soil types. The proposed sensor depends on the frequency domain reflectometry (FDR) technique and is called the WET sensor. It estimates the dielectric permittivity (K-a) and bulk electrical conductivity (sigma(a)) of soil. Then, it utilizes both of them to estimate theta and sigma(p). The new sensor is compared to time domain reflectometry (TDR) measurements. Time domain reflectometry is a well established technique for K-a and sigma(a) measurements in soils. The study involves experimental measurements in the laboratory using five different soil types and a range of theta values. In each soil type, three different electrical conductivity solutions (sigma(w)) were used. The results revealed that the calibration coefficients of water content and the soil parameter are significantly dependent on the soil type and slightly affected by electrical conductivity of the moistening solution.
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| 8. |
- Hamed, Yasser, et al.
(författare)
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Comparison of soil salinity and solute transport for different cultivated soil types in northeastern Egypt
- 2008
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 53:2, s. 466-478
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Tidskriftsartikel (refereegranskat)abstract
- The soil salinity distribution and solute transport properties of three different soil types were investigated and compared within a project area in northeastern Egypt. For this purpose, dye tracer experiments and salinity sampling were carried out. The resulting salinity maps showed that the soil salinity in the cultivated western site of the project area is 8-10 times higher than that in the cultivated eastern site. However, the cultivated soil displayed significantly lower salinity with higher uniformity as compared to the uncultivated soil. The preferential flow phenomenon was less apparent in the cultivated soil. This is mainly due to tillage which disrupts the structure of the soil so that deep cracks are no longer connected to the soil surface. This reduces the risk for groundwater contamination through preferential flow. The study showed that careful and continuous monitoring of the salinity status is needed now and in the future.
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| 9. |
- Jebari, Sihem, et al.
(författare)
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Regionalizing short-term rainfall affected by topography in semiarid Tunisia
- 2007
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 52:6, s. 1199-1215
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Tidskriftsartikel (refereegranskat)abstract
- The characteristics of fine time-scale rainfall are important in many hydrological applications, such as infiltration, erosion and flooding. The spatial properties of such rainfall are, however, seldom known, especially for arid and semi-arid areas. A better knowledge of fine time-scale rainfall and also comparison with daily rainfall may yield possibilities for disaggregation. For this purpose, rainfall data of different time scales, from 1-min to daily, from 25 stations during four years (1995–1998), were spatially analysed by means of spatial correlation, empirical orthogonal function (EOF) and hierarchical clustering. The results show that the spatial correlation is typically non-isotropic and varying, depending on topography and local meteorological settings. Similarly, spatial patterns of EOF are closely related to main atmospheric synoptic situations as influenced by orography and spatial dependence regarding areas with predominant convective and frontal rainfall. The clustering displayed different homogeneous sub-groups over the Tunisian Dorsal Mountains that can be used to better manage the limited water resources that often depend on fine time-scale rainfall variability.
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| 10. |
- Jinno, Kenji, et al.
(författare)
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Effects of land-use change on groundwater recharge model parameters
- 2009
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 54:2, s. 300-315
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Tidskriftsartikel (refereegranskat)abstract
- Land development usually induces large changes in flood peak and infiltration properties, thus affecting the entire hydrological environment of the area. In order to evaluate such negative effects caused by land-use change, it is necessary to estimate the changes in surface runoff and groundwater recharge rate. The effects of land-use changes on the parameter values of a groundwater recharge model were studied and are presented. The response of groundwater level was examined at several observation wells for two different unconfined aquifers consisting of weathered granite. The spatially calibrated parameters of the groundwater recharge model were classified in order to evaluate the effects of land-use change. It was shown that the parameter values most affected by land-use change were the surface runoff coefficient, F-infinity, followed by the shape parameter, (r)(1/2). The field capacity parameter, R-0, was also greatly affected. By defining the land-use change for these three parameters the hydrological change can be predicted.
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