Modelling the monthly hydrological balance using Soil and Water Assessment Tool(SWAT)model:A case study of the Wadi Mina upstream watershed

Modelling the hydrological balance in semi-arid zones is essential for effective water resource management,encompassing both surface water and groundwater.This study aims to model the monthly hydrological water cycle in the Wadi Mina upstream watershed(northwest Algeria)by applying the Soil and Water Assessment Tool(SWAT)hydrological model.SWAT modelling integrates spatial data such as the Digital Elevation Model(DEM),land use,soil types and various meteorological parameters including precipitation,maximum and minimum temperatures,relative humidity,solar radiation and wind speed.The SWAT model was calibrated and validated using data from January 2012 to December 2014,with a calibra-tion period from January 2012 to August 2013 and a validation period from September 2013 to December 2014.Sensitivity and parameter calibration were conducted using the SWAT-SA program,and model performance evaluation relied on comparing the observed discharge at the outlet of the basin with model-simulated discharge,assessed through statistical coefficients including Nash-Sutcliffe Efficiency(NSE),coefficient of determination(R2)and Percent Bias(PBAIS).Calibration results indicated favourable objec-tive function values(NSE=0.79,R2=0.93,PBAIS=-8.53%),although a slight decrease was observed during validation(NSE=0.69,R2=0.86,and PBAIS=-11.41%).The application of the SWAT model to the Wadi Mina upstream watershed highlighted its utility in simulating the spatial distribution of different components of the hydrological balance in this basin.The SWAT model revealed that approximately 71%of the precipitation in the basin evaporates,while only 29%contributes to surface runoff or infiltration into the soil.

Hydrodynamic Simulation of the Pagasitikos Gulf, Greece

Semi-enclosed sea basins have difficulty in recharging their waters due to limited communication with larger water bodies, with understandable consequences for their environmental status. This paper aims at the computational simulation of the hydrodynamic characteristics of the waters of the Pagasitikos Gulf (Greece), which has limited communication and water exchange with the Aegean Sea and is subject to intense environmental pressures The Estuary, Lake & Coastal Ocean 3d hydrodynamic Model (ELCOM 2.2) combined with its later version Aquatic Ecosystem Model-3d (AEM3D) were used for the simulation. The simulation included the topography of the area, the bay’s bottom geometry, atmospheric loadings, tides, the influence of the Coriolis force and boundary conditions. The hydrodynamic behaviour of the bay, water circulation, velocities at the surface and in depth, water recharge and residence time throughout the bay, density variation and other factors were examined to determine the impact of all these on the aquatic ecosystem.

The Hydrodynamic Behaviour of Euboean Gulf Coastal Areas and the Mixing of the Physico-Chemical Characteristics of Urban Sewage Discharged into Them under the Influence of Climate Change

The hydrodynamic circulation within the marine environment is a complex phenomenon, characterized by the interplay of strong tidal forces, atmospheric influences, and bathymetric features. The physical and hydrodynamic attributes of this flow play a pivotal role in promoting vertical mixing of seawater masses, thereby facilitating the integration of their physical and chemical parameters, including nutrients and oxygen. Additionally, they are instrumental in governing the dispersion and diffusion of pollutants originating from urban sewage, contributing to the overall water renewal process and environmental quality. This study investigates the potential impact of anticipated increases in average air temperatures on water column stratification in coastal regions susceptible to these dynamic influences. These areas receive treated urban sewage, and the study aims to assess how these temperature changes might influence the dispersion and mixing of pollutant loads present in these coastal waters.

The Impact of Climate Change on the Stratification of Coastal Areas of the Euboean Gulf and the Diffusion of Urban Wastewater in Them

Hydrodynamic circulation in a marine environment, characterized by the influence of strong tides, atmospheric loading and bathymetry, is a complex phenomenon. The physical and hydrodynamic characteristics of this flow are absolutely crucial for the vertical mixing of the sea masses and consequently for the mixing of their physico-chemical parameters, such as nutrients and oxygen, as well as for the diffusion and dispersion of passive pollutants, the recharge of the waters and the general environmental situation. This paper examines the effect of a future increase in mean air temperature on the water column stratification of coastal areas of interest, which are subject to the above loadings and receive treated urban wastewater, and how this increase could affect their diffusion and mixing of conservative pollutants contained therein.

地下水水源保护区范围计算的KLF法及其在徐州张集地区的应用

详细介绍了地下水水源保护区范围的计算方法:Krijgsman-Lobo-Ferreira(KLF)法,分别推导出了正水流梯度方向、负水流梯度方向和垂直于地下水流方向保护区范围的计算公式,并就方法的适用性及参数取值等问题进行了探讨。在徐州张集地区应用的结果表明,KLF法提供了一种计算地下水保护区范围的便捷、科学、有效的方法,计算结果对于确定地下水源保护区范围及有效保护地下水源具有实际意义。

Effect of Under Connected Plates on the Hydrodynamic Efficiency of the Floating Breakwater

In this paper, the hydrodynamic efficiency of a floating breakwater system is experimentally studied by use of physical models. Regular waves with wide ranges of wave heights and periods are tested. The efficiency of the breakwater is presented as a function of the wave transmission, reflection, and energy dissipation coefficients. Different parameters affecting the breakwater efficiency are investigated, e.g. the number of the under connected vertical plates, the length of the mooring wire, and the wave length. It is found that, the transmission coefficient kt decreases with the increase of the relative breakwater width B/L, the number of plates n and the relative wire length l/h, while the reflection coefficient kr takes the opposite trend. Therefore, it is possible to achieve kt values smaller than 0.25 and kr values larger than 0.80 when B/L is larger than 0.25 for the case of l/h-1.5 and n=4. In addition, empirical equations used for estimating the transmission and reflection coefficients are developed by using the dimensionless analysis, regression analysis and measured data and verified by different theoretical and experimental results.

Experimental Study of Pore Pressure and Deformation of Suction Bucket Foundations Under Horizontal Dynamic Loading

Centrifuge experiments are carried out to investigate the responses of suction bucket foundations under horizontal dynamic loading. The effects of loading amplitude, the size of the bucket and the structural weight on the dynamic responses are investigated. It is shown that, when the loading amplitude is over a critical value, the sand at the upper part around the bucket softens or even liquefies. The liquefaction index （excess pore pressure divided by initial effective stress. In this paper, the developmental degree of excess pore pressure is described by liquefaction index） decreases from the upper part to the lower part of the sand foundation in the vertical direction and decreases from near to far away from the bucket＇s side wall in the horizontal direction, large settlements of the bucket and the sand around the bucket are induced by the horizontal dynamic loading. The dynamic responses of the bucket of a smaller height （when the diameter is the same） are heavier. A cyclic crack some distance near the bucket occurs in the sand.

Prototype observation and influencing factors of environmental vibrationinduced by flood discharge

Due to a wide range of field vibration problems caused by flood discharge at the Xiangjiaba Hydropower Station, vibration characteristics and influencing factors were investigated based on prototype observation. The results indicate that field vibrations caused by flood discharge have distinctive characteristics of constancy, low frequency, small amplitude, and randomness with impact, which significantly differ from the common high-frequency vibration characteristics. Field vibrations have a main frequency of about 0.5-3.0 Hz and the characteristics of long propagation distance and large-scale impact. The vibration of a stilling basin slab runs mainly in the vertical direction. The vibration response of the guide wall perpendicular to the flow is significantly stronger than it is in other directions and decreases linearly downstream along the guide wall. The vibration response of the underground turbine floor is mainly caused by the load of unit operation. Urban environmental vibration has particular distribution characteristics and change patterns, and is greatly affected by discharge, scheduling modes, and geological conditions. Along with the increase of the height of residential buildings, vibration responses show a significant amplification effect. The horizontal and vertical vibrations of the 7th floor are, respectively, about 6 times and 1.5 times stronger than the corresponding vibrations of the 1st floor. The vibration of a large-scale chemical plant presents the combined action of flood discharge and working machines. Meanwhile, it is very difficult to reduce the low-frequency environmental vibrations. Optimization of the discharge scheduling mode is one of the effective measures of reducing the flow impact loads at present. Choosing reasonable dam sites is crucial.

Optimal dosing time of acid algaecide for restraining algal growth

Restraining algal growth by algaecide has been studied by many researchers, but the dosing time has not yet been studied. In this study, we examined the appropriate dosing time of algaecide through a series of experiments. In the experiments, the pH value of water is significantly affected by Microcystis aeruginosa, and the variation of the pH value is in favor of the growth of the alga. Therefore, using acid algaecide in the period with maximum pH values, i.e., the stable phase, would change the acidity-alkalinity of the water significantly, and would negatively affect algal growth. Acid algaecide does not eliminate the alga effectively if the acid algaecide is dosed in the logarithmic growth phase. Using acid algaecide in the decline phase after algal bloom not only is unfavorable for eliminating the alga, but also prolongs the decline phase, and even brings about next larger algal bloom.

Control of Seepage through Earth Dams Based on Pervious Foundation Using Toe Drainage Systems

Many dangerous effects arise from seepage through earth dams based on pervious layer. Therefore, the dam embankment must be provided with seepage control measures to avoid such effects. In the present work, different control methods were used such as flat slopes, toe drainage systems, and a catch drain in the tail water. The hydraulic performance of each control measure was evaluated using the analytical solutions, previously developed, to estimate the seepage quantity (q), the height of seepage surface (h3), and the coordinates of the free surface (hx). Study was conducted on a physical model for a dam embankment having a top width (b) = 10.0 meter, height (Hd) = 30.0 meter, and slope factor (m) = 1.5. The obtained results were analyzed and presented in dimensionless charts. Results showed that, the used control measures possess a great effect on the characteristics of seepage through earth dams based on pervious foundations. A comparative study was conducted between the studied toe drainage systems to enable the designers the better choice for design purposes.

Theory of Combined Seepage Applied to Dewatering Systems

In the present study, an analytical solution is presented to solve the problem of combined seepage, under a sheet piling cofferdam, applied to dewatering systems. Existence of the sheet pile creates a confined seepage followed by an unconfined seepage in the same field, which presents a combined seepage problem. Two equations were developed to analyze the combined seepage underneath a sheet piling wall. Using such equations, both the maximum height of the free surface just behind the sheet piling cofferdam (Ho) and the quantity of seepage discharge to be pumped out from the construction site (q) can be determined. The main parameters affecting the combined seepage characteristics underneath a sheet piling wall are: The depth of permeable foundation layer (T), the horizontal distance behind the sheet pile (X), the depth of excavation in the construction site (D), the embedded depth of sheet pile (S), the retained water head (H1), the accumulated seepage water depth (H2), and the side slope factor of excavation line (M). Study showed that, the above parameters have a great effect on the combined seepage, but with different extents.

Dam Breach Analysis Using HEC-RAS and HEC-GeoRAS: The Case of Kesem Kebena Dam

Ethiopia has been booming with active construction of dams within the past few decades for different infrastructural needs, but has never experienced demolition or failure of dams in its history;hence little attention is being given to possible breach scenarios of dams and the resulting floodings. This paper makes analysis of the possible breach of kesem dam and the resulting flood inundation. In this study, the dam has been checked for both overtopping and piping failure modes using one dimensional river analysis model called HEC-RAS. Empirical equations were used to predict dam breach parameters of the two failure modes for use in this model. PMF inflow with a peak 9237.77 m3/s is used as an input to the reservoir to check if overtopping failure was possible. The spill way has proven to have adequate capacity for the flood due to the PMF. Therefore, breaching of the embankment was not possible. Piping failure was also simulated in HEC-RAS and the resulting breach due to piping failure, was analyzed and flood hydrograph was obtained at different cross sections along the river. These are flood hydrographs at 20 km, 40 km and 60 km at the downstream. The resulting flood plain was also mapped using HEC-GeoRas to show the extent of flooding.

Automatic Fast and Robust Technique to Refine Extracted SIFT Key Points for Remote Sensing Images

The scale-invariant feature transform(SIFT)ability to automatic control points(CPs)extraction is very well known on remote sensing images,however,its result inaccurate and sometimes has incorrect matching from generating a small number of false CPs pairs,their matching has high false alarm.This paper presents a method containing a modification to improve the performance of the SIFT CPs matching by applying sum of absolute difference(SAD)in different manner for the new optical satellite generation called near-equatorial orbit satellite(NEqO)and multi-sensor images.The proposed method leads to improving CPs matching with a significantly higher rate of correct matches.The data in this study were obtained from the RazakSAT satellite covering the Kuala Lumpur-Pekan area.The proposed method consists of three parts:(1)applying the SIFT to extract CPs automatically,(2)refining CPs matching by SAD algorithm with empirical threshold,and(3)evaluating the refined CPs scenario by comparing the result of the original SIFT with that of the proposed method.The result indicates an accurate and precise performance of the model,which showed the effectiveness and robustness of the proposed approach.

Introduction to rainwater management in Australia and suggestions for China's water problems

Australia is one of the world leaders in water management. The country meets the challenge of water shortage with established integrated water management in which rainwater is taken as a too precious resource to be just drained off. In Australia, rainwater is extensively harvested and polished to provide cheaper supply for potable and non-potable domestic uses, irrigation, landscaping, refilling aquifers and other uses. Implementing dual management over the quantity and quality of storm water and practicing water sensitive urban design (WSUD) in urban areas effectively control non-point-source pollution of waterways by pollutants carried with runoffs, reduce the discharge of rainwater and thus protect properties and lives from damage by floods. These achievements are attributed to constant reinforcement by govenments from federal to local levels in policy, financial, legal and educational aspects, and also to the lasting efforts of professional communities and water industry in developing requisite techniques, demonstrating the benefits and fostering public credence of rainwater reuse. The successful rainwater management practices in Australia suggest rainwater harvesting can be a complimentary means for the South-to-North Water Transfer Scheme to solve the water shortage in China's northern regions, and thus release to a degree the pressure on the Yangtze water resources. Best management practices of rainwater can be an effective controlling strategy for flooding and non-point-source water pollution of waterways. Such in-site source control initiatives have particular significance to protecting slow waterways of weak self-purification ability, like the Three Gorges Reservior.

Simulate New Near Equatorial Satellite System by a Novel Multi-Fields and Purposes Remote Sensing Goniometer

Researchers in the remote sensing field use different types of images from satellite systems and simulator devices, such as goniometers. However, no device can simulate the new generation of optical satellite system called near-equatorial satellite system to perform different kinds of remote sensing applications in equatorial regions. This study proposed a newly invented laboratory and fieldwork goniometer designed to simulate and capture intensity variation and measure the bidirectional spectral reflectance of earth surface. The proposed goniometer is a multi-purpose and multi-field device. It is able to simulate different satellite systems and measure the intensity variation and spectral reflectance of earth’s surface features with freely azimuth and zenith angles of sensors and illumination source in fieldwork and/or laboratory. However, the system of invention is focusing on specific satellite orbital to work with the parameters and properties of NEqO satellite system in order to obtain NEqO system imagery for performing different applications such as geometric correction, relative radiometric normalization and change detection for future work. The significant of this invention is that most of the invented goniometers of remote sensing are able to work just in field or just in laboratory and use, carry just optical sensor or hyperspectral sensor. Specifically, our invention can do all these functions that are not available in existing goniometers. The proposed device offers several advantages, namely, high measurement speed, flexibility, low cost, efficiency, and possible measurement depending on the free zenith/azimuth angles of sensors and illumination sources. The proposed goniometer includes ten parts, and two different sensors (optical and hyperspectral).

A Comprehensive Lagrangian Transport Study in A Long-Narrow Bay,Xiangshan Bay,China

Study on the transport and mixing in coastal waters is of great concern to the ocean resources exploitation and ecological system protection.Lagrangian methods are direct and effective of researching mass transport.Two Lagrangian tools were adopted and combined to describe water transport in a long-narrow bay,Xiangshan Bay,China.Based on the fields of tidal velocity simulated from the 3-D hydrodynamic model,Lagrangian Coherent Structures(LCSs)and synoptic Lagrangian maps(SLMs)were calculated in the study area.Through comparison of the results,the features and relation of the two tools were discussed.The results show that the LCSs act as the separatrix of the water regions with different transport characteristics and can identify the water areas with different transport time scales.The comprehensive application of the Lagrangian tools is helpful to obtain more insight into the water transport process.

Flash Flood Risk Assessment Using Morphological Parameters in Sinai Peninsula

Flash floods are considered to be one of the worst weather-related natural disasters. They are sudden and highly unpredictable following brief spells of heavy rain. Egypt is subjected to flash floods, especially the eastern desert and Sinai Peninsula where floods from the mountains of Red Sea and Sinai are causing heavy damage to man-made features. This manuscript presents the methodology adopted to generate a weighted risk map for main watersheds located in Sinai according to main morphological parameters. Using digital elevation model (DEM) implemented into a Geographic Information System (GIS) the Sinai watersheds were delineated and morphological parameters calculated. The parameters where then used in a multi criteria analysis process to calculate a morphological risk factor. The resulted risk maps of this study can help initiating appropriate measures to mitigate the probable hazards in the area with prioritization.

Comparison of Stochastic Models in Forecasting Monthly Streamflow in Rivers: A Case Study of River Nile and Its Tributaries

The dynamic and accurate forecasting of monthly streamflow processes of a river are important in the management of extreme events such as floods and drought, optimal design of water storage structures and drainage network. Many Rivers are selected in this study: White Nile, Blue Nile, Atbara River and main Nile. This paper aims to recommend the best linear stochastic model in forecasting monthly streamflow in rivers. Two commonly hydrologic models: the deseasonalized autoregressive moving average (DARMA) models and seasonal autoregressive integrated moving average (SARIMA) models are selected for modeling monthly streamflow in all Rivers in the study area. Two different types of monthly streamflow data (deseasonalized data and differenced data) were used to develop time series model using previous flow conditions as predictors. The one month ahead forecasting performances of all models for predicted period were compared. The comparison of model forecasting performance was conducted based upon graphical and numerical criteria. The result indicates that deasonalized autoregressive moving average (DARMA) models perform better than seasonal autoregressive integrated moving average (SARIMA) models for monthly streamflow in Rivers.