. Systematic tile drainage is used extensively in agricultural lands to remove excess water and i... more . Systematic tile drainage is used extensively in agricultural lands to remove excess water and improve crop growth; however, tiles can also transfer nutrients from farmlands to downstream surface water bodies, leading to water quality problems. There is a need to simulate the hydrological behaviour of tile drains to understand the impacts of climate or land management change on agricultural runoff. The Cold Regions Hydrological Model (CRHM) is a physically based, modular modelling system that enables the creation of comprehensive models appropriate for cold regions by including a full suite of winter, spring, and summer season processes and coupling these together via mass and energy balances. A new tile drainage module was developed for CRHM to account for this process in tile-drained landscapes that are increasingly common in cultivated basins of the Great Lakes and northern Prairies regions of North America. A robust multi-variable, multi-criteria model performance evaluation strategy was deployed to examine the ability of the module with CRHM to capture tile discharge under both winter and summer conditions. Results showed that soil moisture is largely regulated by tile flow and lateral flow from adjacent fields. The explicit representation of capillary rise for moisture interactions between the rooting zone and groundwater greatly improved model simulations, demonstrating its significance in the hydrology of tile drains in loam soils. Water level patterns revealed a bimodal behaviour that depended on the positioning of the capillary fringe relative to the tile. A novel aspect of this module is the use of field capacity and its corresponding pressure head to provide an estimate of drainable water and thickness of the capillary fringe, rather than a detailed soil retention curve that may not always be available. Understanding the bimodal nature of soil water levels provides better insight into the significance of dynamic water exchange between soil layers below drains to improve tile drainage representation in models.
In this study, the critical (or maximum) discharge rates before saline water enters a well were d... more In this study, the critical (or maximum) discharge rates before saline water enters a well were determined for vertical and horizontal wells in a freshwater aquifer which is separated from a static saline aquifer by a sharp interface. Flow around the well was solved by integration of a point sink solution along the well axis, and both the critical discharge rate and critical interface rise were determined through a comparison of the heads and vertical gradients at the saline–fresh water interface. The rates were determined for vertical and horizontal wells with various lengths and depths for different aquifer salinities. Results were generalized by drawing dimensionless type curves. The results showed that the dimensionless total critical discharge rates are higher for the longer horizontal wells and longer vertical wells with a certain bottom depth, and they almost linearly decrease with well depth at rates of 0.7–0.9. For the dimensionless well length of 0.2, the dimensionless total discharge rate of a horizontal well is about 0.1 more than that of a vertical well with the same length and well-top depth. Also, the critical discharge rates per unit length of well are inversely proportional to well length and remarkably higher for shallower wells. Additionally, the critical pumping rate is proportional to the salinity difference of the aquifers. These results were confirmed by comparison to existing solutions for vertical wells with dimensionless lengths of 0.2, 0.5 and 0.6, and for critical interface rises in the range of 0.75–0.9.RésuméDans cette étude, les débits critiques (ou maximaux) avant que l’eau salée pénètre un puits ont été déterminés pour des puits horizontaux et verticaux dans un aquifère d’eau douce qui est séparé d’un aquifère salin statique par une interface nette. L’écoulement autour d’un puits a été résolu en intégrant une solution ponctuelle de puits le long de l’axe du puits, et à la fois le débit critique et l’augmentation de l’interface critique ont été déterminés par comparaison des charges hydrauliques et des gradients verticaux au niveau de l’interface eau douce eau salée. Les débits ont été déterminés pour les puits verticaux et horizontaux pour différentes longueurs et profondeur pour différentes salinités d’aquifère. Les résultats ont été généralisés en dessinant des courbes types adimensionnelles. Les résultats ont montré que les débits totaux critiques adimensionnels sont plus grands pour les puits horizontaux les plus longs et pour les puits verticaux les plus longs avec une certaine profondeur du fond, et ils décroissent pratiquement de manière linéaire avec la profondeur des puits pour des débits compris entre 0.7 et 0.9. Pour une longueur de puits adimensionnelle de 0.2, le débit total adimensionnel d’un puits horizontal est environ 0.1 plus élevé que pour un puits vertical de même longueur et profondeur. En outre, les débits critiques totaux par unité de longueur d’un puits sont inversement proportionnels à la longueur du puits et remarquablement bien plus élevés pour les puits peu profonds. De plus, le débit critique de pompage est proportionnel à la différence de salinité des aquifères. Ces résultats ont été confirmés par comparaison aux solutions existantes pour les puits verticaux ayant des longueurs adimensionnelles de 0.2, 0.5 et 0.6 et pour des augmentations de l’interface critique dont la gamme de valeur est comprise entre 0.75 et 0.9.ResumenEn este estudio, se determinaron los ritmos de descarga crítica (o máxima) antes que el agua salina ingrese en un pozo en relación a pozos verticales y horizontales en un acuífero de agua dulce que está separado de un acuífero salino estático por una interfaz nítida. El flujo alrededor del pozo fue resuelto por la integración de una solución de punto sumidero a lo largo del eje del pozo, y se determinaron tanto el ritmo de la descarga crítica y la elevación crítica de la interfaz a través de una comparación de las cargas hidráulicas y los gradientes verticales en la interfaz agua salada–dulce. Los ritmos se determinaron para pozos verticales y horizontales con varias longitudes y profundidades para salinidades diferentes de los acuíferos. Los resultados se generalizaron confeccionando curvas tipo adimensionales. Los resultados muestran que los ritmos críticos de descargas totales adimensionales son mayores para los pozos horizontales y los pozos verticales más largos con una cierta profundidad del fondo, y ellos disminuyen casi linealmente con la profundidad del pozo a un ritmo de 0.7–0.9. Para una longitud del pozo adimensional de 0.2, el ritmo de descarga total adimensional de un pozo horizontal es de aproximadamente 0.1 más que la de un pozo vertical con la misma longitud y profundidad del tope del pozo. Además, los ritmos críticos de descarga por unidad de longitud son inversamente proporcionales a la longitud del pozo y marcadamente mayores para los pozos someros. Además, el ritmo crítico de bombeo es proporcional a la…
Artificial recharge (AR) is a method to balance and recover groundwater resources. AR has been th... more Artificial recharge (AR) is a method to balance and recover groundwater resources. AR has been the main and parsimonious solution for water scarcity problems in the arid and semiarid Middle East for thousands of years. This technique is increasingly being encouraged and at present there has been a renewed interest to find improved methods for AR in many arid countries. AR may be defined as augmenting the natural infiltration of surface water into underground formations by various techniques such as by spreading of water in infiltration basins or by artificially changing recharge conditions (Todd and Mays, 2005). Unconfined aquifers can be artificially recharged by spreading of water on the ground surface. AR by water spreading is practiced in 36 multipurpose floodwater spreading stations in Iran since 1983. The systems serve as sedimentation basins and infiltration ponds for the AR of groundwater and also as experimental plots for investigation of several problems such as sediment stabilization and afforestation (Kowsar, 1992). Due to water shortage in Gareh-Bygone Plain, arid south-eastern Iran, a Floodwater Spreading System (FWS) to artificially recharge the groundwater was established between 1983 and 1987 on about 2000 ha. This system is an inexpensive method for flood mitigation and AR of aquifers that results in a large economic return for relatively small investment. Estimation of recharged water is a crucial subject in aquifer management. A variety of techniques are available to quantify recharge. However, choosing appropriate techniques is often difficult (Scanlon et al., 2002). In order to estimate the recharged water for a 14-year period, a 3D conceptual model was built to be representative of the study area and efficient estimation of hydraulic parameters. Groundwater flow was simulated and calibrated by MODFLOW-2000 based on monthly observed data during both steady and transient periods for the years between 1993 and 2007. The aquifer parameters including hydraulic conductivities, specific yield, and recharge rate were determined through calibration of model during steady state, unsteady state with no recharge, and unsteady state with recharge cases, respectively. The recharge amount varied from a few hundred thousand cubic meters per month during drought periods to about 4.5 million cubic meters per month during rainy periods. This study aimed at assessing the effects of different strategies to improve the efficiency of the FWS using the above groundwater model. The study focused on spatial distribution of the system, change in the hydraulic structures and hydraulic parameters of the aquifer, and application of different abstraction scenarios in order to increase the efficiency and management of the system. The results will be used to better manage existing and plan new FWS projects in order to achieve sustainable water resources using an economical and efficient AR system in arid areas. (Less)
Axisymmetric flow to a well is an important topic of groundwater hydraulics, the simulation of wh... more Axisymmetric flow to a well is an important topic of groundwater hydraulics, the simulation of which depends on accurate computation of head gradients. Groundwater numerical models with conventional rectilinear grid geometry such as MODFLOW (in contrast to analytical models) generally have not been used to simulate aquifer test results at a pumping well because they are not designed or expected
Water use efficiency (WUE) can be calculated using a range of methods differing in carbon uptake ... more Water use efficiency (WUE) can be calculated using a range of methods differing in carbon uptake and water use variable selection. Consequently, inconsistencies arise between WUE calculations due to complex physical and physiological interactions. The purpose of this study was to quantify and compare WUE estimates (harvest or flux-based) for alfalfa (C3 plant) and maize (C4 plant) and determine effects of input variables, plant physiology and farming practices on estimates. Four WUE calculations were investigated: two “harvest-based” methods, using above ground carbon content and either precipitation or evapotranspiration (ET), and two “flux-based” methods, using gross primary productivity (GPP) and either ET or transpiration. WUE estimates differed based on method used at both half-hourly and seasonal scales. Input variables used in calculations affected WUE estimates, and plant physiology led to different responses in carbon assimilation and water use variables. WUE estimates were...
Globally, maize (Zea mays, a C4-plant) and alfalfa (Medicago sativa, a C3-plant) are common and e... more Globally, maize (Zea mays, a C4-plant) and alfalfa (Medicago sativa, a C3-plant) are common and economically important crops. Predicting the response of their water use efficiency, WUE, to changing hydrologic and climatic conditions is vital in helping farmers adapt to a changing climate. In this study, we assessed the effective leaf area index (eLAI - the leaf area most involved in CO2 and H2O exchange) and stomatal conductance in canopy scale in maize and alfalfa fields. In the process we used a theoretically-based photosynthesis C3-C4 model (C3C4PM) and carbon and water vapour fluxes measured by Eddy Covariance towers at our study sites. We found that in our study sites the eLAI was in the range of 25-32% of the observed total LAI in these crops. WUEs were in range of 8-9 mmol/mol. C3C4PM can be used in predictions of stomatal conductance and eLAI responses in C3 and C4 agricultural crops to elevated CO2 concentration and changes in precipitation and temperature under future climate scenarios.
Desalination to increase irrigation water supply for agricultural production is becoming importan... more Desalination to increase irrigation water supply for agricultural production is becoming important in water-scarce regions. While desalination has positive effects on the potential irrigation water quantity and quality, the technique may also be a considered potential source of groundwater pollution. The present study investigated the effects of desalination wastewater discharge on groundwater quality in an arid area in southern Iran for the 2012-2017 period. The chemical composition of the groundwater samples was evaluated considering pH, EC, Na + , Ca 2+ , Mg 2+ , SO 4 2+ , Cl − , and HCO 3 −. The suitability of groundwater for drinking and irrigation purposes as well as spatial pattern of groundwater pollution was analyzed. The results showed that mean concentration of Na + , Ca 2+ , Mg 2+ , SO 4 2− , and Cl − in all investigated wells increased from 148, 94, 46, 247, and 257 mg/L in 2012 to 282, 146, 71, 319, and 582 mg/L in 2017, respectively. Using Gibb's diagram, it was s...
Agricultural P losses are a global economic and water quality concern. Much of the current unders... more Agricultural P losses are a global economic and water quality concern. Much of the current understanding of P dynamics in agricultural systems has been obtained from rainfall-driven runoff, and less is known about cold-season processes. An improved understanding of the magnitude, form, and transport flow paths of P losses from agricultural croplands year round, and the climatic drivers of these processes, is needed to prioritize and evaluate appropriate best management practices (BMPs) to protect soil-water quality in cold regions. This study examines multiyear, year-round, high-frequency edge-of-field P losses (soluble reactive P and total P [TP]) in overland flow and tile drainage from three croplands in southern Ontario, Canada. Annual and seasonal budgets for water, P, and estimates of field P budgets (including fertilizer inputs, crop uptake, and runoff) were calculated for each site. Annual edge-of-field TP loads ranged from 0.18 to 1.93 kg ha yr (mean = 0.59 kg ha yr) across the region, including years with fertilizer application. Tile drainage dominated runoff across sites, whereas the contribution of tiles and overland flow to P loss differed regionally, likely related to site-specific topography, soil type, and microclimate. The nongrowing season was the dominant period for runoff and P loss across sites, where TP loss during this period was often associated with overland flow during snowmelt. These results indicate that emphasis should be placed on BMPs that are effective during both the growing and nongrowing season in cold regions, but that the suitability of various BMPs may vary for different sites.
Large diameter fully cased wells that gain water from the bottom are often dug in sandy and colla... more Large diameter fully cased wells that gain water from the bottom are often dug in sandy and collapsible aquifers. They have cylindrical vertical walls lined with brick or concrete. The well bottom is partially filled with aquifer material through which the flow is vertically upward. When the vertical hydraulic gradient reaches a critical value, quicksand occurs and the well structure
In this study the effect of irrigation by dam water in Bigherd area (Fars Province, Iran) on grou... more In this study the effect of irrigation by dam water in Bigherd area (Fars Province, Iran) on groundwater quality 1 and 3 years after dam construction was investigated. To conduct this study the major ion concentrations, including HCO3−, Ca2+, Mg2+, Na+, K+, SO42− and Cl− and water levels in ten water wells and the dam reservoir were measured during two periods (June 2009 and June 2011), analyzed by factor analysis and plotted in water quality charts. The results of factor analysis show that most of the dissolved ions including Mg2+, Ca2+, SO42−, Cl− and HCO3−, particularly in 2009, were mainly originated from carbonate and evaporitic formations as well as from the playa lake (Factor 1). In 2011, elevated salinity levels were found to be mainly related to intense evaporation during irrigation that are proportional to Na+ and K+ concentrations (Factor 2) and depend on the type of crop and irrigation method. It was also found that the surface waters from deeper origins had less of an effect on groundwater recharge compared to upstream carbonate aquifers.
. Systematic tile drainage is used extensively in agricultural lands to remove excess water and i... more . Systematic tile drainage is used extensively in agricultural lands to remove excess water and improve crop growth; however, tiles can also transfer nutrients from farmlands to downstream surface water bodies, leading to water quality problems. There is a need to simulate the hydrological behaviour of tile drains to understand the impacts of climate or land management change on agricultural runoff. The Cold Regions Hydrological Model (CRHM) is a physically based, modular modelling system that enables the creation of comprehensive models appropriate for cold regions by including a full suite of winter, spring, and summer season processes and coupling these together via mass and energy balances. A new tile drainage module was developed for CRHM to account for this process in tile-drained landscapes that are increasingly common in cultivated basins of the Great Lakes and northern Prairies regions of North America. A robust multi-variable, multi-criteria model performance evaluation strategy was deployed to examine the ability of the module with CRHM to capture tile discharge under both winter and summer conditions. Results showed that soil moisture is largely regulated by tile flow and lateral flow from adjacent fields. The explicit representation of capillary rise for moisture interactions between the rooting zone and groundwater greatly improved model simulations, demonstrating its significance in the hydrology of tile drains in loam soils. Water level patterns revealed a bimodal behaviour that depended on the positioning of the capillary fringe relative to the tile. A novel aspect of this module is the use of field capacity and its corresponding pressure head to provide an estimate of drainable water and thickness of the capillary fringe, rather than a detailed soil retention curve that may not always be available. Understanding the bimodal nature of soil water levels provides better insight into the significance of dynamic water exchange between soil layers below drains to improve tile drainage representation in models.
In this study, the critical (or maximum) discharge rates before saline water enters a well were d... more In this study, the critical (or maximum) discharge rates before saline water enters a well were determined for vertical and horizontal wells in a freshwater aquifer which is separated from a static saline aquifer by a sharp interface. Flow around the well was solved by integration of a point sink solution along the well axis, and both the critical discharge rate and critical interface rise were determined through a comparison of the heads and vertical gradients at the saline–fresh water interface. The rates were determined for vertical and horizontal wells with various lengths and depths for different aquifer salinities. Results were generalized by drawing dimensionless type curves. The results showed that the dimensionless total critical discharge rates are higher for the longer horizontal wells and longer vertical wells with a certain bottom depth, and they almost linearly decrease with well depth at rates of 0.7–0.9. For the dimensionless well length of 0.2, the dimensionless total discharge rate of a horizontal well is about 0.1 more than that of a vertical well with the same length and well-top depth. Also, the critical discharge rates per unit length of well are inversely proportional to well length and remarkably higher for shallower wells. Additionally, the critical pumping rate is proportional to the salinity difference of the aquifers. These results were confirmed by comparison to existing solutions for vertical wells with dimensionless lengths of 0.2, 0.5 and 0.6, and for critical interface rises in the range of 0.75–0.9.RésuméDans cette étude, les débits critiques (ou maximaux) avant que l’eau salée pénètre un puits ont été déterminés pour des puits horizontaux et verticaux dans un aquifère d’eau douce qui est séparé d’un aquifère salin statique par une interface nette. L’écoulement autour d’un puits a été résolu en intégrant une solution ponctuelle de puits le long de l’axe du puits, et à la fois le débit critique et l’augmentation de l’interface critique ont été déterminés par comparaison des charges hydrauliques et des gradients verticaux au niveau de l’interface eau douce eau salée. Les débits ont été déterminés pour les puits verticaux et horizontaux pour différentes longueurs et profondeur pour différentes salinités d’aquifère. Les résultats ont été généralisés en dessinant des courbes types adimensionnelles. Les résultats ont montré que les débits totaux critiques adimensionnels sont plus grands pour les puits horizontaux les plus longs et pour les puits verticaux les plus longs avec une certaine profondeur du fond, et ils décroissent pratiquement de manière linéaire avec la profondeur des puits pour des débits compris entre 0.7 et 0.9. Pour une longueur de puits adimensionnelle de 0.2, le débit total adimensionnel d’un puits horizontal est environ 0.1 plus élevé que pour un puits vertical de même longueur et profondeur. En outre, les débits critiques totaux par unité de longueur d’un puits sont inversement proportionnels à la longueur du puits et remarquablement bien plus élevés pour les puits peu profonds. De plus, le débit critique de pompage est proportionnel à la différence de salinité des aquifères. Ces résultats ont été confirmés par comparaison aux solutions existantes pour les puits verticaux ayant des longueurs adimensionnelles de 0.2, 0.5 et 0.6 et pour des augmentations de l’interface critique dont la gamme de valeur est comprise entre 0.75 et 0.9.ResumenEn este estudio, se determinaron los ritmos de descarga crítica (o máxima) antes que el agua salina ingrese en un pozo en relación a pozos verticales y horizontales en un acuífero de agua dulce que está separado de un acuífero salino estático por una interfaz nítida. El flujo alrededor del pozo fue resuelto por la integración de una solución de punto sumidero a lo largo del eje del pozo, y se determinaron tanto el ritmo de la descarga crítica y la elevación crítica de la interfaz a través de una comparación de las cargas hidráulicas y los gradientes verticales en la interfaz agua salada–dulce. Los ritmos se determinaron para pozos verticales y horizontales con varias longitudes y profundidades para salinidades diferentes de los acuíferos. Los resultados se generalizaron confeccionando curvas tipo adimensionales. Los resultados muestran que los ritmos críticos de descargas totales adimensionales son mayores para los pozos horizontales y los pozos verticales más largos con una cierta profundidad del fondo, y ellos disminuyen casi linealmente con la profundidad del pozo a un ritmo de 0.7–0.9. Para una longitud del pozo adimensional de 0.2, el ritmo de descarga total adimensional de un pozo horizontal es de aproximadamente 0.1 más que la de un pozo vertical con la misma longitud y profundidad del tope del pozo. Además, los ritmos críticos de descarga por unidad de longitud son inversamente proporcionales a la longitud del pozo y marcadamente mayores para los pozos someros. Además, el ritmo crítico de bombeo es proporcional a la…
Artificial recharge (AR) is a method to balance and recover groundwater resources. AR has been th... more Artificial recharge (AR) is a method to balance and recover groundwater resources. AR has been the main and parsimonious solution for water scarcity problems in the arid and semiarid Middle East for thousands of years. This technique is increasingly being encouraged and at present there has been a renewed interest to find improved methods for AR in many arid countries. AR may be defined as augmenting the natural infiltration of surface water into underground formations by various techniques such as by spreading of water in infiltration basins or by artificially changing recharge conditions (Todd and Mays, 2005). Unconfined aquifers can be artificially recharged by spreading of water on the ground surface. AR by water spreading is practiced in 36 multipurpose floodwater spreading stations in Iran since 1983. The systems serve as sedimentation basins and infiltration ponds for the AR of groundwater and also as experimental plots for investigation of several problems such as sediment stabilization and afforestation (Kowsar, 1992). Due to water shortage in Gareh-Bygone Plain, arid south-eastern Iran, a Floodwater Spreading System (FWS) to artificially recharge the groundwater was established between 1983 and 1987 on about 2000 ha. This system is an inexpensive method for flood mitigation and AR of aquifers that results in a large economic return for relatively small investment. Estimation of recharged water is a crucial subject in aquifer management. A variety of techniques are available to quantify recharge. However, choosing appropriate techniques is often difficult (Scanlon et al., 2002). In order to estimate the recharged water for a 14-year period, a 3D conceptual model was built to be representative of the study area and efficient estimation of hydraulic parameters. Groundwater flow was simulated and calibrated by MODFLOW-2000 based on monthly observed data during both steady and transient periods for the years between 1993 and 2007. The aquifer parameters including hydraulic conductivities, specific yield, and recharge rate were determined through calibration of model during steady state, unsteady state with no recharge, and unsteady state with recharge cases, respectively. The recharge amount varied from a few hundred thousand cubic meters per month during drought periods to about 4.5 million cubic meters per month during rainy periods. This study aimed at assessing the effects of different strategies to improve the efficiency of the FWS using the above groundwater model. The study focused on spatial distribution of the system, change in the hydraulic structures and hydraulic parameters of the aquifer, and application of different abstraction scenarios in order to increase the efficiency and management of the system. The results will be used to better manage existing and plan new FWS projects in order to achieve sustainable water resources using an economical and efficient AR system in arid areas. (Less)
Axisymmetric flow to a well is an important topic of groundwater hydraulics, the simulation of wh... more Axisymmetric flow to a well is an important topic of groundwater hydraulics, the simulation of which depends on accurate computation of head gradients. Groundwater numerical models with conventional rectilinear grid geometry such as MODFLOW (in contrast to analytical models) generally have not been used to simulate aquifer test results at a pumping well because they are not designed or expected
Water use efficiency (WUE) can be calculated using a range of methods differing in carbon uptake ... more Water use efficiency (WUE) can be calculated using a range of methods differing in carbon uptake and water use variable selection. Consequently, inconsistencies arise between WUE calculations due to complex physical and physiological interactions. The purpose of this study was to quantify and compare WUE estimates (harvest or flux-based) for alfalfa (C3 plant) and maize (C4 plant) and determine effects of input variables, plant physiology and farming practices on estimates. Four WUE calculations were investigated: two “harvest-based” methods, using above ground carbon content and either precipitation or evapotranspiration (ET), and two “flux-based” methods, using gross primary productivity (GPP) and either ET or transpiration. WUE estimates differed based on method used at both half-hourly and seasonal scales. Input variables used in calculations affected WUE estimates, and plant physiology led to different responses in carbon assimilation and water use variables. WUE estimates were...
Globally, maize (Zea mays, a C4-plant) and alfalfa (Medicago sativa, a C3-plant) are common and e... more Globally, maize (Zea mays, a C4-plant) and alfalfa (Medicago sativa, a C3-plant) are common and economically important crops. Predicting the response of their water use efficiency, WUE, to changing hydrologic and climatic conditions is vital in helping farmers adapt to a changing climate. In this study, we assessed the effective leaf area index (eLAI - the leaf area most involved in CO2 and H2O exchange) and stomatal conductance in canopy scale in maize and alfalfa fields. In the process we used a theoretically-based photosynthesis C3-C4 model (C3C4PM) and carbon and water vapour fluxes measured by Eddy Covariance towers at our study sites. We found that in our study sites the eLAI was in the range of 25-32% of the observed total LAI in these crops. WUEs were in range of 8-9 mmol/mol. C3C4PM can be used in predictions of stomatal conductance and eLAI responses in C3 and C4 agricultural crops to elevated CO2 concentration and changes in precipitation and temperature under future climate scenarios.
Desalination to increase irrigation water supply for agricultural production is becoming importan... more Desalination to increase irrigation water supply for agricultural production is becoming important in water-scarce regions. While desalination has positive effects on the potential irrigation water quantity and quality, the technique may also be a considered potential source of groundwater pollution. The present study investigated the effects of desalination wastewater discharge on groundwater quality in an arid area in southern Iran for the 2012-2017 period. The chemical composition of the groundwater samples was evaluated considering pH, EC, Na + , Ca 2+ , Mg 2+ , SO 4 2+ , Cl − , and HCO 3 −. The suitability of groundwater for drinking and irrigation purposes as well as spatial pattern of groundwater pollution was analyzed. The results showed that mean concentration of Na + , Ca 2+ , Mg 2+ , SO 4 2− , and Cl − in all investigated wells increased from 148, 94, 46, 247, and 257 mg/L in 2012 to 282, 146, 71, 319, and 582 mg/L in 2017, respectively. Using Gibb's diagram, it was s...
Agricultural P losses are a global economic and water quality concern. Much of the current unders... more Agricultural P losses are a global economic and water quality concern. Much of the current understanding of P dynamics in agricultural systems has been obtained from rainfall-driven runoff, and less is known about cold-season processes. An improved understanding of the magnitude, form, and transport flow paths of P losses from agricultural croplands year round, and the climatic drivers of these processes, is needed to prioritize and evaluate appropriate best management practices (BMPs) to protect soil-water quality in cold regions. This study examines multiyear, year-round, high-frequency edge-of-field P losses (soluble reactive P and total P [TP]) in overland flow and tile drainage from three croplands in southern Ontario, Canada. Annual and seasonal budgets for water, P, and estimates of field P budgets (including fertilizer inputs, crop uptake, and runoff) were calculated for each site. Annual edge-of-field TP loads ranged from 0.18 to 1.93 kg ha yr (mean = 0.59 kg ha yr) across the region, including years with fertilizer application. Tile drainage dominated runoff across sites, whereas the contribution of tiles and overland flow to P loss differed regionally, likely related to site-specific topography, soil type, and microclimate. The nongrowing season was the dominant period for runoff and P loss across sites, where TP loss during this period was often associated with overland flow during snowmelt. These results indicate that emphasis should be placed on BMPs that are effective during both the growing and nongrowing season in cold regions, but that the suitability of various BMPs may vary for different sites.
Large diameter fully cased wells that gain water from the bottom are often dug in sandy and colla... more Large diameter fully cased wells that gain water from the bottom are often dug in sandy and collapsible aquifers. They have cylindrical vertical walls lined with brick or concrete. The well bottom is partially filled with aquifer material through which the flow is vertically upward. When the vertical hydraulic gradient reaches a critical value, quicksand occurs and the well structure
In this study the effect of irrigation by dam water in Bigherd area (Fars Province, Iran) on grou... more In this study the effect of irrigation by dam water in Bigherd area (Fars Province, Iran) on groundwater quality 1 and 3 years after dam construction was investigated. To conduct this study the major ion concentrations, including HCO3−, Ca2+, Mg2+, Na+, K+, SO42− and Cl− and water levels in ten water wells and the dam reservoir were measured during two periods (June 2009 and June 2011), analyzed by factor analysis and plotted in water quality charts. The results of factor analysis show that most of the dissolved ions including Mg2+, Ca2+, SO42−, Cl− and HCO3−, particularly in 2009, were mainly originated from carbonate and evaporitic formations as well as from the playa lake (Factor 1). In 2011, elevated salinity levels were found to be mainly related to intense evaporation during irrigation that are proportional to Na+ and K+ concentrations (Factor 2) and depend on the type of crop and irrigation method. It was also found that the surface waters from deeper origins had less of an effect on groundwater recharge compared to upstream carbonate aquifers.
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