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Numerical understanding of regional scale water table behavior in the Guadalupe Valley aquifer, Baja California, Mexico
J. R. Campos-Gaytan,T. Kretzschmar
Hydrology and Earth System Sciences Discussions , 2006,
Abstract: A regional groundwater flow model was developed, in order to evaluate the water table behavior in the region of the Guadalupe Valley, in Baja California, Mexico. The State of Baja California has been subject to an increment of the agricultural, urban and industrials activities, implicating a growing water-demand. However, the State is characterized by its semi-arid climate with low surface water availability; resulting in an extensive use of groundwater in local aquifer. Based on historic piezometric information of the last two decades, however, a negative evolution could be observed, resulting a negative storage volume. So far, there is not an integral hydrogeological evaluation that determine the real condition of the groundwater resource, and that permit to planning a management of the Guadalupe Valley Aquifer. A steady-state calibration model was carried out in order to obtain the best possible match to measured levels at the Guadalupe Valley Aquifer. The contours of calculated water table elevations for January 1983 were reproduced. Generally, the comparison of the observed and calculated water table configurations have a good qualitative and quantitatively adjustment. Nowadays, it is count with a hydrogeological model that can be used for simulates the groundwater flow in the region of the Guadalupe Valley.
Efecto de la calidad de agua del acuífero Valle de Guadalupe en la salinidad de suelos agrícolas Water quality effect on the Valle de Guadalupe aquifer in the agricultural soils salinity  [cached]
Jorge Arturo Salgado Tránsito,Oscar Palacios Vélez,Arturo Galvis Spínola,Francisco Gavi Reyes
Revista mexicana de ciencias agrícolas , 2012,
Abstract: Para determinar el efecto de la calidad del agua en el Acuífero del Valle de Guadalupe, Baja California, México, en la salinidad de los suelos agrícolas se midió el pH, conductividad eléctrica, sólidos disueltos totales y la concentración de los principales iones en las aguas de 66 pozos, de un total de 754 que se encontraban en operación en el acuífero durante 2009 .Y se analizó en el extracto de pasta de saturación de muestras de suelo el pH, conductividad eléctrica, carbonato, bicarbonato, cloruro, sulfato, boro, fósforo, nitrato, calcio, magnesio, sodio, potasio, amonio. El 74% de los suelos estudiados presenta una cantidad superior a 15 mg kg-1 de nitratos, y por tratarse de suelos arenosos se atribuyen problemas de contaminación a las aplicaciones de fertilizantes nitrogenados. La salinidad del agua está presente en todo acuífero del Valle de Guadalupe (clasificada como C3 y C4 en 85.9%), pero la salinidad del suelo (pHpromedio= 7.6) no se presenta en el total de la superficie del valle; por lo tanto el agua del acuífero no es la única causante de dicho problema, el manejo del agua para riego y la aplicación de fertilizantes deben ser estudiados para cuantificar su contribución a la salinidad del suelo. In order to determine the effect of water quality in the Valle de Guadalupe aquifer, Baja California, Mexico, in the agricultural soils salinity the pH, electrical conductivity, total dissolved solids and the concentration of major ions in water of 66 wells were measured, from 754 that were in operation in the aquifer during 2009. The pH, electrical conductivity, carbonate, bicarbonate, chloride, sulfate, boron, phosphorus, nitrate, calcium, magnesium, sodium, potassium, and ammonium were analyzed in the paste extract saturation of the soil samples. 74% of the soils studied presented an amount higher than 15 mg kg-1 of nitrate, and due to sandy soils, contamination problems are attributed to nitrogen fertilizer applications. Water salinity is presentthroughout Valle de Guadalupe aquifer (classified as C3 and C4 in 85.9%), but soil salinity (pHmean= 7.6) is not present in the total area of the valley, so the aquifer water is not the only cause of the problem, water management for irrigation and fertilizer application should be studied to quantify their contribution to the soild salinity.
Geophysical characterization of the Etla Valley aquifer, Oaxaca, Mexico  [PDF]
E. L. Flores-Márquez,R. E. Chávez,R. G. Martínez-Serrano,J. Herrera-Barrientos
Geofísica internacional , 2001,
Abstract: The water supply needs of the city of Oaxaca have increased considerably over the last twenty years. The aquifer that produces 80% of the total water in the region is located in the Valley of Etla, to the NW of the city. Intensive exploitation of the aquifer has reduced the water quality. Basin geometry was estimated from 2.5-D models along four profiles, three W-E and one N-W. The sedimentary thickness reaches up to 730 m. Gravity and geologic interpretations suggest that the Mesozoic mylonites of the Sierra de Juárez and the metamorphic rocks of the Sierra de Oaxaca underlie the sedimentary infill. The fault pattern controls the tectonic behavior of the region and groundwater circulation. The Valley of Etla is a steep graben bounded by the Etla and Oaxaca faults. The main aquifers are in the Tertiary and Quaternary horizons. Twenty-three Vertical Electrical Soundings (VES) across the central part of the valley yield a thickness of the first aquifer of 20 m to 50 m. Wells in the area were used to control the resistive horizons and the stratigraphy. Electric tomography studies in the southern portion of the valley showed the base of the first aquifer at 50 m depth. The water-bearing sedimentary layers increase in thickness to the north of the valley, following the basement. Electromagnetic measurements reveal a vadose zone of at least 20 m thickness towards the center of the Valley. Zones of low resistivity were found in the northern and southern sections of the Valley. A possible contamination is suggested towards the northern portion of the City of Oaxaca.
The Source of Arsenic and Nitrate in Borrego Valley Groundwater Aquifer  [PDF]
Mohammad Hassan Rezaie-Boroon, Jessica Chaney, Bradley Bowers
Journal of Water Resource and Protection (JWARP) , 2014, DOI: 10.4236/jwarp.2014.617145
Abstract: Groundwater in California is very precious, yet what we can withdraw is often contaminated with natural and anthropogenic pollution sources. We have examined the Borrego Valley (BV) groundwater (N = 6 wells) in southern California to understand the source of arsenic and nitrate in some of its groundwater production wells. The results show that the arsenic values range from <2 ppb to 12.2 ppb and the nitrate values from <1 ppm to 10.2 ppm for different wells respectively. The results showed that the arsenic concentration increased 270% for the well # ID1-10 since 2004 and showed an increase of 63% since 2013 respectively. For other wells the results showed an increase of 147% and 72% since 2001. The nitrate concentration has jumped 42% in concentration since last year in one of the wells. The objective of this study is to understand the nature and source of arsenic and nitrate in BV groundwater aquifer as to how this change in arsenic and nitrate concentration occurs through the time. The arsenic retention in the sediments is highly variable and controlled by local processes as a result of natural weathering process of metamorphic bedrock. The second results from the development of strongly reducing conditions at near-neutral pH values, leading to the desorption of arsenic from mineral oxides and to the reductive dissolution of Fe and Mn oxides, also leading to arsenic release. The high arsenic concentrations in some groundwater wells in Borrego Valley CA require the need for reconnaissance surveys in mineralized areas of fractured crystalline basement. Net groundwater extraction values are based on an irrigation efficiency of 78 percent with 14 to 22 percent irrigation return. We believe that the return flow from irrigational activity could be one of the major sources of nitrate transferring the agricultural contaminants such as nitrate to Borrego Valley aquifer.
Hydrogeology and groundwater pollution of Yaqui Valley, Sonora, Mexico  [cached]
Rodrigo González,Luis E. Marín,Gustavo Córdova
Geofísica internacional , 1997,
Abstract: We use the G.O.D. criteria to evaluate the vulnerability of the Yaqui Valley aquifer from drill hole data and water table maps. The pollutant loads are identified and quantified and the aquifer pollution risk was calculated from the aquifer vulnerability and the pollution load. The most vulnerable zones are in the West, and the most important contributions of pollutants are from industrial, agricultural, livestock and population centers. The highest aquifer pollution risk areas are Central, West and East.
Efecto de la calidad de agua del acuífero Valle de Guadalupe en la salinidad de suelos agrícolas
Salgado Tránsito, Jorge Arturo;Palacios Vélez, Oscar;Galvis Spínola, Arturo;Gavi Reyes, Francisco;Mejía Sáenz, Enrique;
Revista mexicana de ciencias agrícolas , 2012,
Abstract: in order to determine the effect of water quality in the valle de guadalupe aquifer, baja california, mexico, in the agricultural soils salinity the ph, electrical conductivity, total dissolved solids and the concentration of major ions in water of 66 wells were measured, from 754 that were in operation in the aquifer during 2009. the ph, electrical conductivity, carbonate, bicarbonate, chloride, sulfate, boron, phosphorus, nitrate, calcium, magnesium, sodium, potassium, and ammonium were analyzed in the paste extract saturation of the soil samples. 74% of the soils studied presented an amount higher than 15 mg kg-1 of nitrate, and due to sandy soils, contamination problems are attributed to nitrogen fertilizer applications. water salinity is presentthroughout valle de guadalupe aquifer (classified as c3 and c4 in 85.9%), but soil salinity (phmean= 7.6) is not present in the total area of the valley, so the aquifer water is not the only cause of the problem, water management for irrigation and fertilizer application should be studied to quantify their contribution to the soild salinity.
The hydrogeology of the Uitenhage Artesian Basin with reference to the Table Mountain Group Aquifer
LGA Maclear
Water SA , 2001,
Abstract: The Uitenhage Artesian Basin (UAB) lies in the Eastern Cape and is South Africa's most important artesian groundwater basin, supplying approximately 1 400 Ml/yr (44 l/s) of water from springs for domestic use to Uitenhage, as well as supporting large citrus irrigation schemes. Groundwater from this basin has been extensively utilised from the early part of the 20th century, including periods of over-exploitation resulting in the declaration of a groundwater control area to limit abstraction to sustainable rates. The aquifer comprises fractured Table Mountain Group (TMG) sandstones confined in the eastern part of the basin by overlying Cretaceous siltstones and mudstones, resulting in artesian conditions. The Coega Fault is a major structural feature dividing the basin into separate systems, viz. the southern Swartkops Aquifer and the northern Coega Ridge Aquifer, that are hydrogeologically independent of each other. The Elands River syncline divides the Swartkops Aquifer further into the Kruisrivier and Bethelsdorp Units. Borehole yields commonly range from 5 to 10 l/s and the groundwater quality is excellent with low salinities. Water hardening, however, is required due to the acidic and corrosive nature of the groundwater, typical of other Table Mountain Group aquifers in South Africa. Using 14C data, the age of the groundwater in the basin ranges from 1 500 to 28 000 years with a calculated flow rate of 0.8 m/a. From the chloride mass balance method, recharge rates are determined to be 25 to 55% of annual rainfall. Groundwater temperatures generally show that depths of groundwater strikes do not necessarily correspond with depth of origin, indicating a complex groundwater circulation pattern within the basin. Whilst the UAB has been well studied locally, a basin-scale hydrogeological characterisation is considered to be necessary, followed by recommendations and formulation of a management plan to ensure the continued sustainability of groundwater supply from this national asset. WaterSA Vol.27(4) 2001: 499-506
Numerical modeling of Etla Valley aquifer, Oax., Mexico: Evolution and remediation scenarios
Flores-Márquez, E. L.;Martínez-Serrano, R. G.;Chávez, R. E.;Crusillo, Y;Jiménez, G;Campos-Enriquez, O;
Geofísica internacional , 2008,
Abstract: short-term evolution (for 2001, 2005 and 2015) for the shallow aquifer of etla valley, oaxaca, southern mexico, was simulated based in a 3d hydrological model elaborated from the available geological, geophysical, geochemical, and hydrologic parameters. the numerical simulations were based on visual modflow code. these simulations indicate that, if the actual extraction regime is maintained, the drawdown of the potentiometric surface will get worse to the se of the study area (i. e. beneath oaxaca city). the prevailing aquifer flow direction favors the ground water pollution by fertilizers and leakage from the sewage network (dumped to the atoyac river). according to the numerical simulation, remediation of this situation is possible if the wells located in the neigborhood of oaxaca city are relocated at the recharge zones (i. e. at the feet from sierra de juárez). this remediation scenario will allow a recovery of the drawdown of the potentiometric surface.
Numerical modeling of Etla Valley aquifer, Oax., Mexico: Evolution and remediation scenarios  [PDF]
E. L. Flores-Márquez,R. G. Martínez-Serrano,R. E. Chávez,Y. Crusillo
Geofísica internacional , 2008,
Abstract: Short-term evolution (for 2001, 2005 and 2015) for the shallow aquifer of Etla Valley, Oaxaca, southern Mexico, was simulated based in a 3D hydrological model elaborated from the available geological, geophysical, geochemical, and hydrologic parameters. The numerical simulations were based on Visual MODFLOW code. These simulations indicate that, if the actual extraction regime is maintained, the drawdown of the potentiometric surface will get worse to the SE of the study area (i. e. beneath Oaxaca city). The prevailing aquifer flow direction favors the ground water pollution by fertilizers and leakage from the sewage network (dumped to the Atoyac river).According to the numerical simulation, remediation of this situation is possible if the wells located in the neigborhood of Oaxaca City are relocated at the recharge zones (i. e. at the feet from Sierra de Juárez). This remediation scenario will allow a recovery of the drawdown of the potentiometric surface.
Aquifer vulnerability mapping in the Turbio river valley, Mexico: A validation study  [PDF]
José Alfredo Ramos Leal,Ramiro Rodríguez Castillo
Geofísica internacional , 2003,
Abstract: Aquifer vulnerability assessments can be made using quantitative methods such as DRASTIC and AVI. Their typical output maps are generally not validated or verified with field data. This paper proposes validation alternatives for aquifer vulnerability mapping. The DRASTIC mapping of the Turbio river valley, in Guanajuato State, Mexico comprises an area of 1300 km2. Comparing it with another aquifer vulnerability map generated by the AVI method, it could be validated. DRASTIC parameter comparison was also applied. A rescaling of the original DRASTIC rating range is proposed and justified based on the analysis of its effective weight. The vulnerability tendencies obtained were correlated with observed hydrogeochemical information. The observed values for chloride and TDS agree with the vulnerable areas defined by DRASTIC and AVI. Those areas correspond to the riverbed of the León-Turbio fluvial system. Some potential pollution sources are located in the vulnerable zones. The results demonstrate the importance of validation alternatives. They also show how in the most vulnerable areas, solutes coming from pollution sources are affecting the groundwater quality.
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