A multi-period optimization model for conjunctive surface water–ground water use via aquifer storage and recovery in Corpus Christi,Texas

The present study develops and evaluates a decision support system for the conjunctive management of the current surface and proposed aquifer storage and recovery (ASR) facility of the city of Corpus Christi, TX using a simulation–optimization approach. The objective of the model is to maximize water storage in the surface and subsurface storage units while meeting (1) the freshwater inflow requirements to the Corpus Christi estuary and (2) the water demands of the city and its service area. The model is parameterized using streamflow data from the U. S. Geological Survey gauging stations on the Nueces River and its tributaries as well as long-term climatic data and regional hydrogeologic information. Results indicate that a single-well field ASR facility is capable of storing approximately 925 ha-m (7,500 ac-ft) of water over a 5-year period in the Evangeline Aquifer with a total potential storage of about 2,715 ha-m (22,000 ac-ft) of water over the jurisdictional area of the Corpus Christi Aquifer Storage and Recovery Conservation District. Surplus surface water sources are seen to contribute approximately 49–96 % of the water stored in the ASR during the simulation period. The remaining storage came from either Choke Canyon Reservoir or Lake Corpus Christi, which also resulted in a slight reduction in evapotranspiration in both reservoirs. The analysis indicates that the proposed ASR system is not limited on the supply side but multiple well fields may be required to increase the storage capacity within the aquifer.     

Numerical analysis on seepage failures of dike due to water level-up and rainfall using a water–soil-coupled smoothed particle hydrodynamics model

For seepage failures of dike due to water level-up and rainfall, surface infiltration and strength change induced by suction reduction are important factors; thus, numerical analysis should consider the coupling of water and soil, as well as the effect of saturation to obtain more precise failure mechanism. Based on the advanced smoothed particle hydrodynamics (SPH) method, this work proposed a two-phase-coupled SPH model in coordination with a novel constitutive model for unsaturated soils. Then, a triaxial compression test is simulated to check the applicability of the SPH method on the soil phase. After that, the failure test of a dike due to water level-up is discretized and simulated, from which the seepage process, the distribution of maximum shear strain, the slip surface, and pore water pressure are obtained. The two-phase-coupled SPH model is also applied to a slope failure test of heavy rainfall, and the results are compared to the model test. Finally, a dike failure test due to rainfall is analyzed using the proposed SPH model to reproduce the surface infiltration and suction reduction. The proposed SPH model provides several insights of seepage failures and can be a helpful tool for the analysis of dike failures induced by water level-up and rainfall.     

Hydrochemical model and probable pollution in the water of Euphrates River (Qaem–Falluja)

The study of hydrochemical models and probable pollution in Euphrates River from Qaem–Al-Falluja was performed through regime observation in ten water points. The hydrochemical properties of Euphrates River waters are determined by using the analysis results of 21 physico-chemical variables during the water year (2008). The interpretation of the hydrochemical phenomena is achieved in accordance with the statistical results of Polynomial Regression Statistic, calculating the coefficient of variation among the physico-chemical components of the water terminating by 14 models. The results of monitoring during the water year 2008 indicate a pollution case by SO₄ and Cd in Ramadi and downstream stations; TDS, Mg, Na, Cl, Mn, and CO₂ in Ramadi station; TDS, Ca, Na, Cl, and Fe in Baghdadi station; and Ca and H _T in Qaem station and Mg in Obaydi station. The research suggests the best locations for hydrochemical monitoring as continuous hydrologic stations used for the long-term monitoring. These stations are in Qaem city as inlet location and Al-Baghdadi and Ramadi cities terminating in Falluja city as outlet location. Furthermore, daily record system is recommended for the other stations in each city to complete the regime observation of Euphrates water type. From the configuration approach of hydrochemical models with the pollution phenomena, there are potential point sources of pollution such as municipal effluent pipes and reused water from mining process for building materials in the first sector of river, which extends between Qaem and Haditha dam. Also groundwater seepages and springs discharge of mineralized water mixed with sewage water from cities act as potential point sources of pollution on the river water in the second sector extended between Haditha and Ramadi scheme. The third sector of the river is affected by all reasons in the first and second sectors as well as the effectiveness of agricultural activities throughout drainage canals and irrigation projects extended between Ramadi and Falluja cities.     

Hazard-based evaluation model of water inrush disaster sources in karst tunnels and its engineering application

Water inrush is one of the typical geological hazards that may occur during tunnel construction in a karst area. In this paper, a potential model is established based on attribute mathematics, to assess the risk of water inrush. First, the CaCO₃ content of regional strong karst, thickness of the regional strong karst layer, groundwater recharge area, discharge of groundwater, average temperature characteristic, groundwater level, groundwater cycle characteristic, surface karst morphology, fault structure, fold structure, and monoclinal structure are chosen as evaluation indexes of water inrush based on the principles of scientificity, rationality, operability, and representativeness. Second, the objective weight calculation formula is used to calculate the weights of the evaluation indices, and attribute measurement functions of each evaluation index are constructed to reckon the attribute measurement of a single index and synthetic attribute measurement. Lately, the identification and classification of water and mud inrush hazard in tunnels have been performed using a confidence criterion. In this paper, hazard level is graded as one of four types. The hazard-based assessment methodology is applied to the construction site of the Jigongling Tunnel along the entire Fanba Expressway route, and the findings are compared against the site’s actual situation. The results of the engineering practice show that the evaluation result is consistent with the actual construction situation; thus, the method can provide scientific guidance for tunnel construction units.     

Construction of soil–water characteristic curve of granular materials with toroidal model and artificially generated packings

Acta Geotechnica - The soil–water characteristic curve (SWCC) of granular materials is crucial for many emerging engineering applications, such as permeable pavement and methane hydrate...     

Sobol’ sensitivity analysis of parameters in the common land model for simulation of water and energy fluxes

The water and energy transfer of land surface is complex due to its large spatial and temporal variability. The modeling and simulation is an important means to study land water and energy transfer, but most selection and analysis of model parameters are empirical and qualitative. This paper has proposed a method of quantitatively identifying the most influential parameters of Common Land Model through Sobol?? sensitivity analysis. Considering sensible heat flux as the model output, the first order and total sensitivity indices of 25 model input parameters are estimated using an improved Sobol?? method. The simulated results are resampled using a bootstrapping method and the corresponding sensitivity indices are calculated. Confidence intervals for the bootstrapping sensitivity indices are estimated by using a percentile method. The results show that the parameters phi0 and porsl are the most important parameters, followed by ref(2,1), tran(2,1) and bsw. Five out of 25 parameters need to have an accurate evaluation, while the other parameters are fixed to a certain value. The sensitivity indices of parameters phi0 and porsl are decreasing after precipitation, while the sensitivity indices of parameters tran(2, 1) and ref(2, 1) are increasing after precipitation.     

Bromine and water quality – Selected aspects and future perspectives

Bromine is a microelement present in waters, both in inorganic and in a wide range of organic compounds, though at lower concentrations. Typically, concentrations of organobromine compounds in waters are several orders of magnitude lower than of bromides. Two issues are addressed in the paper: the influence of bromides on the quality of treated waters and organobromines as contaminants of natural waters. Bromide presence in treated water gives rise to formation of potentially mutagenic disinfection by-products (DBPs). Registered amounts of DBPs in potable waters, exceeding the admissible levels, and the published data on DBPs in waters used for leisure and recreation activities, clearly indicate the health risk. Major sources are identified and registered concentrations of EDB, DBCB, methyl bromide, bromacil and PBDEs in the aquatic environment are summarized. The effects of bromide on DBPs formation and numerous examples of organobromine contamination of the aquatic environment indicate that the presence of bromides and organobromine compounds in the aquatic environment will have to be given more consideration, for several reasons. Firstly, larger amounts of bromide are present in saline and contaminated waters and the proportion of such waters being handled is increasing. Similarly, the processes of water purification, treatment and disinfection are now playing a major role. Secondly, emissions from manufacturing of bromine-containing materials growing, due to, inter alia, intensive development of the electronic industry and the plastic manufacturing sector. Thirdly, bromine compounds are also used as medicine ingredients. There is now a growing awareness of the presence of pharmaceuticals in the aquatic environment. Fourth, low bromide concentrations in hypergene zones may be modified in the future, partly because of the climate changes, which may give rise to difficulties with water treatment systems.Water quality standards having relevance to water used for consumption are based only on the best-known (most widespread) DBPs. However new more restrictive legal regulations relating to the use of bromine compounds have been put in place prohibiting the use of certain bromine-based substances or restricting their amount in finished products. In the light of current legislation, the monitoring of water contamination with potentially toxic, mutagenic and endocrine-disrupting organobromine compounds is still unsatisfactory because newly discovered compounds are not included and certain factors governing the exposure to those substances are still left out.The effects of bromine (bromide and organobromine compounds) on water quality have been investigated by researchers from several fields of expertise. The water management authorities ought to make use of the available research data and identify the problems which need to be addressed directly and those which may emerge in the future.     

An improved BP neural network based on evaluating and forecasting model of water quality in Second Songhua River of China

Taking the Second Songhua River which lies in the northeast of China as a study area, this paper firstly designs the improved BP neural network water evaluating and forecasting model of which 13 water evaluating items are selected as nodes in input layer; 6 classes of evaluating results are selected as nodes of output layer; then, with the ＂0, 1＂ identified pattern and continually practiced comparisons, ＂13-9-5-6＂ double hidden layers with optimized training structure are confirmed; on the basis of this work, the water quality of the Second Songhua River was evaluated and forecasted at the end. The results showed that in the six classes of predefined water quality in 157 stations, none of them belongs to class Ⅰ, and classes Ⅱ, Ⅲ, Ⅳ and Ⅴ are as follows： 8.91%, 58.59%, 18.47%, 1.91% and 12.1%, respectively; the precision of these evaluating and forecasting results is 82.8%.     

Geochemical characterization of surface water and spring water in SE Kashmir Valley,western Himalaya: Implications to water–rock interaction

Water samples from precipitation, glacier melt, snow melt, glacial lake, streams and karst springs were collected across SE of Kashmir Valley, to understand the hydrogeochemical processes governing the evolution of the water in a natural and non-industrial area of western Himalayas. The time series data on solute chemistry suggest that the hydrochemical processes controlling the chemistry of spring waters is more complex than the surface water. This is attributed to more time available for infiltrating water to interact with the diverse host lithology. Total dissolved solids (TDS), in general, increases with decrease in altitude. However, high TDS of some streams at higher altitudes and low TDS of some springs at lower altitudes indicated contribution of high TDS waters from glacial lakes and low TDS waters from streams, respectively. The results show that some karst springs are recharged by surface water; Achabalnag by the Bringi stream and Andernag and Martandnag by the Liddar stream. Calcite dissolution, dedolomitization and silicate weathering were found to be the main processes controlling the chemistry of the spring waters and calcite dissolution as the dominant process in controlling the chemistry of the surface waters. The spring waters were undersaturated with respect to calcite and dolomite in most of the seasons except in November, which is attributed to the replenishment of the CO₂ by recharging waters during most of the seasons.     

Thermodynamics of ice polymorphs and ‘ice-like’ water in hydrates and hydroxides

Thermodynamic properties of water, in various families of hydroxides, oxihydroxides and hydrates (chlorides, chlorates, sulfates and sulfites …), have been calculated by using a large number of data available in the literature. A phase diagram of water has been used to find the first complete set of thermodynamic properties at 298 K, 1 bar of 8 ice polymorphs, from Ih (hexagonal ice, the common polymorph) to IX (very low temperature and high pressure polymorph). These results are used to illustrate the concept of ‘ice-like water’ available for a very large number of hydrated phases (noted X.H₂O) in which water is attached to the corresponding anhydrous substrate (noted X) within a large spectrum of different enthalpies (Δ_fH°) or Gibbs free energies (Δ_fG°), but within a relatively small range of others properties. Heat capacity (Cp°), entropy (S°), and volume (V°) of hydration water (X.H₂O−X=H₂O) appeared to be very close to those characterizing ice polymorphs such as ice II or ice VIII. This concept allows the authors to propose a classification of minerals in terms of affinity for water and to predict the relative stability of hydrated and dehydrated phases under climatic variations.     

OH defects in quartz in the system quartz–albite–water and granite–water between 5 and 25?kbar

The incorporation of OH defects in quartz from the systems quartz–water, quartz–albite–water and granite–water at pressures between 5 and 25?kbar and temperatures between 800 and 1,000?°C was investigated by IR spectroscopy. The two most important OH absorption features can be assigned to hydrogarnet defects (absorption band at 3,585?cm^?1) and coupled substitutions involving Al³⁺ (Al–H defects, absorption bands at 3,310, 3,378 and 3,430?cm^?1). Al incorporation in quartz is controlled by mineral/melt partitioning (D _Al ^Qz/Melt ?=?0.01) and exhibits a negative pressure dependence. This trend is not clearly reflected by the concentration of Al–H defects, which shows positive deviations from the theoretical 1:1 correlation of Al/H for some samples. In contrast to the Al–H defects, formation of hydrogarnet defects appears to be positively correlated to pressure and water activity, and may be used a petrological indicator. The overall water concentration exhibits only minor changes with pressure and temperature, but a clear correlation of water activity (controlled by various amounts of dissolved salts) and hydrogarnet substitution could be established.     

Experimental study of octanol–water partition coefficients for2,4,6-trichlorophenol and pentachlorophenol: Derivation of an empirical model of chlorophenol partitioning behaviour

The octanol–water partition coefficients (log K_ow) of 2,4,6-trichlorophenol and pentachlorophenol were determined as functions of pH, ionic strength and aqueous metal content. For both chlorophenols, the log K_ow exhibits pH dependence in the range pK_a−1<pH<pK_a+3. At lower and higher pH values, the behaviour of the chlorophenols is independent of pH. The present data, in conjunction with that of pre-existing data, indicate that a linear relationship exists between log K_ow and log ionic strength of the aqueous solution for pentachlorophenol, and the data also suggest that aqueous metal–chlorophenolate complexation can significantly alter the partitioning behaviour. The data reported here was used to obtain an empirical model of the partitioning behaviour based on speciation of the aqueous chlorophenol. The model requires knowledge of the low pH partitioning behaviour, as well as the acidity constant for the particular chlorophenol of interest. Although K_ow values have been measured as a function of pH and/or ionic strength for only pentachlorophenol, the input parameters for our empirical model are readily accessible in the literature for many chlorophenols. The model greatly expands our ability to quantify the hydrophobicity of chlorophenols, enabling accurate estimations of the pH and ionic strength dependencies of the partitioning behaviour over a wide range of pH and ionic strength values of environmental interest.     

Which water formed Australian sediment-hosted precious and potch opal?

The means and timing of the formation of Australian sediment-hosted precious opal remain a subject of continuing debate. In this study, the question of which water formed the opal is addressed by examination of rare earth element data for opals and host rocks. The available data, mainly for Lightning Ridge, NSW, suggest a positive Eu anomaly, relative to the neighbouring Sm and Dy, occurs in opals whereas no such anomaly was found for the weathered Cretaceous sediments hosting the opal. Such anomalies may be inherited from the source rock with a similar positive Eu anomaly or generated in situ by severe reduction. There is no indication of major reduction processes during the opal formation that could have led to such a Eu anomaly so this is likely inherited from a source rock. As the opal host rocks did not show this anomaly, the source rocks must be external to the opal fields. Calcite cements within rocks hosting the aquifers of the Eromanga and Surat basins of the Great Artesian Basin have been reported to have a positive Eu anomaly, which strongly suggests that opal was formed by upwelling Great Artesian Basin artesian waters. This work has also highlighted variations in trace-element concentrations in opals, which indicate significant variation in the source water composition during opal formation or different water sources were involved. Either of these is indicative of the source for the opal with its trace elements derived from external sources. These conclusions have significant implications to considerations of how opal formed, and hence, for the exploration for other deposits and to the chemistry and timing that led to the formation of opal.     

All about water and land? Resource-related conflicts in East and West Africa revisited

Recent years have seen an upsurge in the numbers of studies investigating the potential link between climate variability and conflict—and particularly so quantitative studies of this relationship—without reaching any consensus on causal pathways or main findings. This study sets out to explore what the main causes of conflict between resource-user groups in arid and semi-arid areas in Sub-Saharan Africa are, with a particular focus on renewable-resource scarcity. We conduct a comparative analysis of eleven high-quality case studies of the escalation into violence of disputes between pastoralists and farmers or pastoralists in the Western Sahel and East Africa. This enables us to identify the mechanisms underpinning the actors’ motivations. Our analysis shows that the nature of these conflicts is complex. They cannot be reduced to a stimulus (resource scarcity)–response (violence) relationship. We find that drought is a contributing factor in four of the conflicts, and that a poor rainy season plays a role in a fifth one. However, resource scarcity is never the most important cause and it does not explain well the differences in conflict intensity. The most important contributor to explaining different levels of intensity is when local autochthonous and exclusionary claims are coupled with national-level political processes.     

A note on India’s water budget and evapotranspiration

Some recent analyses of India’s water budget are based on information attributed to the Ministry of Water Resources. An examination of the budget components indicates that they imply an evapotranspiration estimate that is significantly lower than what one may expect based on information from other sources. If such is the case, India’s water resources situation may be more dire than is otherwise perceived. For, higher evapotranspiration implies correspondingly reduced availability of water for human use. It should be worthwhile to investigate and reconcile the apparent discrepancy between water budget and evapotranspiration, considering the importance of water in the national context.     

Long-term trend analysis of water table using ‘MAKESENS’ model and sustainability of groundwater resources in drought prone Barind area,NW Bangladesh

In Bangladesh, agriculture plays a major role in the national economy. In the drought prone Barind area in NW Bangladesh, cropping intensity has increased almost double since late eighties of last century (from 1985) because of the introduction of groundwater irrigation. Long-term behavior of groundwater table (GWT) in the drought prone Barind area has been studied using MAKESENS model in the wake of massive installation of tube-wells. The study reveals that the maximum and minimum depths to GWT during 1991-2010 show on average declining trend of 4.51 m and 4.73 m. The long-term prediction for the period of 2020-50 assuming the current rate of groundwater withdrawal is that the declining trend will be 1.16 to 1.59 and 1.07 to 1.82 times more for maximum and minimum groundwater depths respectively in comparison to the present. The rigorous exploitation of groundwater for irrigation, decreasing rainfall and surface geological attributes lead towards declining trend of GWT. This will hamper the country’s food security and ultimately threaten its socio-economic sustainability. So the appropriate strategies for the management of groundwater resource on a sustainable basis should be the priority for maintaining agricultural productivity.     

Influence of the initial water content and dry density on the soil–water retention curve and the shrinkage behavior of a compacted clay

The paper presents the results of an experimental study on the effects of the initial water content and dry density on the soil–water retention curve and the shrinkage behavior of a compacted Lias-clay. The initial conditions after compaction (initial water content and initial dry density) have been chosen on the basis of three Proctor tests of different compaction efforts. According to the eight chosen initial conditions clay samples have been compacted statically. The relation between total suction and water content was determined for the drying path starting from the initial conditions without previous saturation of the specimens. A chilled-mirror dew-point hygrometer was used for the suction measurements. For the investigation of the shrinkage behavior cylindrical specimens were dried to desired water contents step-by-step without previous saturation. The volume of the specimens was measured by means of a caliper. Based on the test results the influence of different initial conditions on the soil suction and the shrinkage behavior is analyzed. The soil–water retention curves obtained in terms of the gravimetric water content are independent of the initial dry density. At water contents above approximately 11–12.5% a strong influence of the compaction water content is observed. At smaller water contents, the soil–water retention curve is independent of the compaction water content. The results of the shrinkage tests show that the influence of the compaction dry density on the shrinkage behavior is negligible. Similar to the drying behavior of saturated samples a primary and a residual drying process could be distinguished. The primary drying process is strongly influenced by the initial water content. In contrast, the rate of the volume change of the residual drying process is unaffected by the initial water content.     

A preliminary evaluation model for reservoir hydrocarbon generating potential established based on dissolved hydrocarbons in oilfield water

OILFIELDWATER,WHICHEXISTSCONCOMITANTLYWITH OILORGASINSUBSURFACERESERVOIRS,ISAKINDOFIMPOR TANTCOMPONENTOFRESERVOIRFLUIDANDALSOISADRIVING FORCEANDCARRIERFORHYDROCARBONMIGRATION,ACCUMULA TIONANDHYDROCARBONRESERVOIRFORMATION.OILFIELDWA TER,HYDROCARBONANDRESER…     

A new mathematical model for soil-column experiment and parameter identification

In this paper, one-dimensional soil-column experiment and its mathematical models were discussed. Due to nonlinear behaviors of solute transport in soil and groundwater, the ordinary retardation factor could be a nonlinear function of solute concentration, and the zero production term could be modified to a nonlinear term related with solute concentration, and then a new mathematical model with nonlinear terms was put forward. Furthermore, an inverse problem of identifying nonlinear source parameters was put forward according to the additional data of breakthrough curves （BTCs）. Numerical simulations for the inverse problem here were carried out by applying gradient regularization （GR） method. Finally, the method was successfully used to explore an actual soil-column experiment in Zhangdian, Zibo, Shandong Province.