Valley Of Mexico Research Articles

Fluoride Exposure through Different Drinking Water Sources in a Contaminated Basin in Guanajuato, Mexico: A Deterministic Human Health Risk Assessment.

Water fluoride levels above the World Health Organization’s guideline (1.5 mg/L), common in overexploited aquifers, represent a health hazard. Our objective was to assess the health risks posed by exposure to fluoride in different drinking water sources in a contaminated basin in Mexico. Fluoride was measured in mutual drinking water sources and in the urine of 39 children and women. Risks were estimated through hazard quotient (HQ) by drinking water source. Dental fluorosis was assessed in the children. Mean fluoride water concentrations (mg/L) were: well, 4.2; waterhole, 2.7; bottled, 2.1; rainwater, 0.4. The mean urinary fluoride concentrations (specific gravity adjusted) were 2.1 mg/L and 3.2 mg/L in children and women, respectively. Our multiple linear regression model showed children’s urinary fluoride concentrations increased 0.96 mg/L for every 1 mg/L increase in water fluoride (p < 0.001). Dental fluorosis was diagnosed in 82% of the children, and their HQ according to drinking water source was: well, 1.5; waterhole, 1.1; bottled, 0.8; harvested rainwater, 0.3. The pervasive dental fluorosis indicates a toxic past fluoride exposure; urinary fluoride levels and HQs indicate high exposure and current health risks for most children. Drinking harvested rainwater will likely prevent most of the local fluoride exposure.

Natural fractures and their relationships to structure, stress, and permeability in the Raton Basin

Fractures in Cretaceous and early Tertiary strata record several deformation events that were imposed on the formations that fill the Raton Basin in Colorado and New Mexico. A regional, generally WNW-ESE striking extension-fracture set is present across much of the basin, but fracturing also includes both dip-slip and strike-slip conjugate shear-fracture sets as well as irregular deformation-band shear fractures. In some areas of the basin, the extension fractures are dynamically-compatible with associated conjugate shear fractures, both recording a maximum compressive stress that was horizontal, trending predominantly WNW-ESE. Fracture strikes vary from NW-SE to ENE-WSW but are approximately normal to the front of the Laramide thrust-fault system that forms the western edge of the basin, implying that fracturing was the result of a horizontal compressive stress anisotropy created by indentation of the thrust system into the basin margin. Fracture anomalies occur over local structures including a N-S basement wrench-fault system that connects two large anticlines within the basin, the Tercio and Vermejo Park anticlines, where N-S strike-slip offset along the basement wrench faults caused folding and fracturing in the overlying strata. The Laramide stress system in the basin changed from thrust-related WNW-ESE horizontal compression to the present-day N-S maximum horizontal compressive stress in mid-Tertiary time as the thrust system became inactive and was replaced by regional E-W extension. No new fracture sets were formed by the re-oriented stress system, although stress-release fractures normal to the regional set formed in outcrops as overlying strata were eroded. Fracture datasets were derived from three sources during this study: outcrops, image logs, and cores. Each source provides a somewhat different perspective on the fractures that enhance permeability in Raton Basin reservoirs. Taken together, the three datasets provide the basis for a relatively complete conceptual model of the Raton fracture system. Fracture-controlled permeability anisotropy will be greatest in the WNW-ESE direction, parallel to the strike of the dominant set of Laramide-age natural fractures, but hydraulic stimulation fractures will propagate N-S, across the strike of those fractures under the influence of the present-day stress system. The apertures of the WNW-ESE fractures will be susceptible to closure under that stress system since the maximum horizontal compressive stress is approximately normal to fracture strike.

Biogeographic analysis of the American genus Echeandia (Asparagoideae, Asparagaceae)

Echeandia (Asparagaceae) is an American genus of herbaceous geophytes. Its distribution is heterogeneous but concentrates along the Mexican Transition Zone (MTZ). We analyzed the species richness distribution and endemism of the group. We compiled a data base of 2,078 records obtained by revision of herbarium specimens, scientific publications, and electronic databases. Species richness was quantified under 4 different criteria. Also, we estimated the weighted endemism and the corrected weighted endemism index to detect centers of endemism. We identified 85 species and registered 74 in Mexico. The MTZ had 61 species and the Sierra Madre del Sur province was the most diverse with 39. The richest cell was located in the Transmexican Volcanic Belt and contained 12 species. In addition, 63 species (85.1%) present in Mexico were endemic. Weighted endemism showed 5 cells in the Sierra Madre del Sur and Balsas Basin in Mexico. In contrast, almost all the high valued cells of corrected weighted endemismindex were located in South America. The results were congruent with the patterns of the geophytes and endemic angiosperms of Mexico. The MTZ has a complex tectonic, volcanic and climatic history. These factors have promoted the diversification of several angiosperm lineages, including Echeandia.

Airborne Lidar Survey, Density-Based Clustering, and Ancient Maya Settlement in the Upper Usumacinta River Region of Mexico and Guatemala

We present results from the archaeological analysis of 331 km2 of high-resolution airborne lidar data collected in the Upper Usumacinta River basin of Mexico and Guatemala. Multiple visualizations of the DEM and multi-spectral data from four lidar transects crossing the Classic period (AD 350–900) Maya kingdoms centered on the sites of Piedras Negras, La Mar, and Lacanja Tzeltal permitted the identification of ancient settlement and associated features of agricultural infrastructure. HDBSCAN (hierarchical density-based clustering of applications with noise) cluster analysis was applied to the distribution of ancient structures to define urban, peri-urban, sub-urban, and rural settlement zones. Interpretations of these remotely sensed data are informed by decades of ground-based archaeological survey and excavations, as well as a rich historical record drawn from inscribed stone monuments. Our results demonstrate that these neighboring kingdoms in three adjacent valleys exhibit divergent patterns of structure clustering and low-density urbanism, distributions of agricultural infrastructure, and economic practices during the Classic period. Beyond meeting basic subsistence needs, agricultural production in multiple areas permitted surpluses likely for the purposes of tribute, taxation, and marketing. More broadly, this research highlights the strengths of HDBSCAN to the archaeological study of settlement distributions when compared to more commonly applied methods of density-based cluster analysis.

Seasonal Changes in Climate Variables in Rainfed Crop Areas in the Lerma-Chapala-Santiago Basin, Mexico

This paper shows the effects of changes in the spatial-temporal behavior and phase shift of climate variables on rainfed agriculture in the Lerma-Chapala-Santiago Basin in central Mexico. Specifically, changes in rainfall (R), maximum temperature (Tmax), and minimum temperature (Tmin) were analyzed over two 25-year periods (1960 to 1985 and 1986 to 2010). Climate surfaces were generated by interpolation using the thin-plate smoothing spline algorithm in the software ANUSPLIN. Climate data were Fourier-transformed and fitted to a sinusoidal curve model, and changes in amplitude (increase) and phase were analyzed. The temporal behavior (1960–2010) indicated that rainfall was the most stable variable at the monthly level and presented no significant changes. However, Tmax increased by 2°C in the final period, and Tmin increased by 0.7°C at the end of the final period. The basin was discretized into ten rainfed crop areas (RCAs) according to the extent of changes in the amplitude and phase of the climate variables. The central and southern portions (55% of the area) presented more significant changes in amplitude, mainly in Tmin and Tmax. The remaining RCAs were smaller (14.6%) but presented greater variation: the amplitude of the Tmin decreased in addition to showing a phase shift, whereas Tmax increased in addition to showing a phase shift. These results translate into a delay in the characteristic temperatures of the spring and summer seasons, which can impact the rainfed crop cycle. Additionally, rainfall showed an annual decrease of approximately 50 mm in all RCAs, which can affect the phenological development of crops during critical stages (emergence through flowering). These changes represent a significant threat to the regional economy and food security of Mexico.

Empires of Xolotl: Two Opening Compositions of the Codex Xolotl

AbstractOnly one of two opening compositions in the Codex Xolotl has been recognized. The conventional version shows the entry of Xolotl, Nopaltzin, and six lesser rulers into the Basin of Mexico from near Tula, Hidalgo, followed by settlement at Xoloc and later a place that will become Tenayuca. The manuscript’s two larger fragments, assembled correctly for the first time, show Xolotl and Nopaltzin observing and moving across a more settled eastern basin into regions to the south ranging from Puebla to Morelos, notably including Cuernavaca. At the same time, they and their six followers are shown settled among caves in the western basin around the future Tenayuca. The two Chichimecs attract fellow Chichimecs from the Cuernavaca region to the Tepetlaoztoc region and trouble ensues. These two realizations of a Chichimec vision of empire are well recorded by the remarkable Aztec graphic communication system. Its portrayal of changes to different ways of life over the centuries reveals an interplay of an oral gathering and hunting culture with a settled society, recording the Chichimec experience and their own way of life with their combined oral and graphic system. Elements of the Chichimecs’ visions of empire endure throughout the Codex Xolotl as its messaging power shines across the contact period and into early colonial times.

Mammal species richness and new records in protected natural areas of the northern part of the metropolitan area of the Valley of México

Sierra de Guadalupe is the only mountain range in the northern part of the Valley of Mexico metropolitan area. The accelerated urban expansion over the past decades has turned Sierra de Guadalupe into an isolated natural area immersed within the urban matrix. This study aimed to gather a documented inventory of the mammals of Sierra de Guadalupe as such information is useful to improve the management, restoration, and conservation of this important natural area of the basin of Mexico. Mammal collection records were extensively surveyed in the literature, collection databases, web pages, and scientific collections; field surveys were also conducted. A taxonomic list of the mammal species and their conservation status in the four Protected Natural Areas of Sierra de Guadalupe was compiled. A species-accumulation curve was constructed using the Chao 1 model and a map showing the distribution of collection records was produced. This work reveals that the mammals of Sierra de Guadalupe include 29 species, 23 genera, 15 families, and six orders. Six species are endemic to Mexico; two of them, Choeronycteris mexicana and Cratogeomys fumosus, are listed as threatened and one, Leptonycteris yerbabuenae, as under special protection. Collection records were gathered from 62 different localities. The largest number of species records and collections were made between 2009 and 2020. The species-accumulation curve projects a total of 36 mammal species. This is the first documented inventory ever compiled of the wild mammals of Sierra de Guadalupe. The species richness observed in this area is remarkable, considering its extension and environmental stressors; in addition, it harbors species endemic to Mexico, some of which are threatened. This is the first time that the species Sorex saussurei, Choeronycteris mexicana, Leptonycteris yerbabuenae, Cratogeomys merriami, Neotomodon alstoni, and Peromyscus melanophryshave been recorded in this area. The species-accumulation curve indicates that our inventory provides a good representation of the local species assemblage. This information can support the formulation of action plans for the conservation and restoration of the biological diversity of these important Protected Natural Areas and the last significant natural area remaining in the northern part of the Valley of Mexico Metropolitan Area.

Physico-chemical Factors an Phytoplankton as Indicators of the Water Quality in Two Periurbans Lakes of a Natural Protected Area in Mexico City

The protected natural area (ANP), Ejidos de Xochimilco and San Gregorio Atlapulco (SGA), is a priority area of ecological conservation in Mexico City (CDMX), that still have remnants of the ancient lake system of the Valley of Mexico watershed that have been modified for decades due to the impact of human activities and that threaten their continuity, despite been declared as a RAMSAR site and historical and cultural heritage of CDMX. Given the above, the present study aimed to compare the spatial-temporal variability of physical-chemical factors and phytoplankton as indicators of anthropogenic impact to diagnose the current state of this locality and propose possible alternatives for sustainable management in the study area. The research design considered comparing the area of channels and lagoons of the SGA wetland in two contrasting climatic seasons: dry and rainy. Eleven sampling stations were delimited: three in the channels area and eight in the lagoons, during the months of March and July. Nine physical-chemical variables were measured: temperature, pH, total solids, conductivity, dissolved oxygen, as well as the concentrations of ammonium, nitrites, nitrates, and soluble phosphorus in surface and bottom samples from each sampling station. The statistical design took into account a factorial design of fixed effects (epochs - locations and strata), with Tukey's "post hoc" test to delimit subsets and various multivariate analysis techniques. Phytoplankton samples were taken in both localities, which were identified down to the genus level, evaluating the relative frequency of the various taxa, as well as their association through the saprobity and diversity indexes. The water quality variables indicated that both the area of channels and the lagoons of the wetland are sites with hypereutrophic characteristics, but the wetland due to its semi-isolation is an area that presents on average levels of nitrates 2.4 times lower than in the channel zone, nitrite concentrations are almost imperceptible, and ammonia is within tolerable limits for the existing biota. It also presents space-time homogeneity in its physical-chemical dynamics, in contrast to the area of channels. The composition of species indicating saprobity also differed between both sites, denoting a lesser impact on the wetland area, so it is suggested to use this site for reintroduction activities of species removed from the channel area and preserve the remaining biota in the lake system.

Mapping salinization and trace element abundance (including As and other metalloids) in the groundwater of north-central Mexico using a double-clustering approach

This study aimed to determine the reliability of the double-clustering method to understand the spatial association and distribution of major and minor constituents in the groundwater of an arid endorheic basin in central Mexico (Comarca Lagunera Region). The results of the double-clustering approach were compared with well-known spatial statistics such as spatial autocorrelations (Moran index) and the local indicator of spatial association (LISA). Fifty-five groundwater samples were collected from diverse wells within the basin, and the major ions, metalloids, and trace elements were determined. Overall, the double-clustering analysis was an effective tool for identifying lithogenic/anthropogenic processes occurring in the basin and for establishing zones with high or low abundance of major ions and trace elements, even where processes affecting the groundwater quality were spatially dispersed. Although 89% of the samples showed As higher than the threshold value of 10 μg/L proposed by the World Health Organization for drinking water, both the double-clustering and LISA analyses identified As hotspots in the alluvial aquifer, where the extraction of deeper and warmer groundwater might promote the concomitant release of the metalloids As, Sb, and Ge and the trace elements V and W. Similarly, both statistical analyses identified mountainous sectors where the weathering of silicates and carbonates plays a key role in the abundance of HCO3−, Ga, and Ba. However, the LISA analysis failed to identify hotspots of carbonate-derived elements such as Ca, Mg, Sr, and U and silicate-derived elements such as Ca, Mg, K, Sr, Rb, Cs, Pb, Ni, and Y. Otherwise, the double-clustering analysis clearly defined high- and low-concentration zones for all these elements in the study region. Unlike the LISA analysis, the double-clustering approach was also successful in determining alluvial areas with high concentrations of Si and Ti and areas where the concentrations of Na, Cl−, SO42−, NO3−, B, Li, Cu, Re, and Se in groundwater were elevated, increasing the groundwater salinity. Overall, this study demonstrated that the double-clustering is an easy-to-apply approach, capable of visualizing disperse zones where specific anthropogenic processes may threaten the groundwater quality.

Matrix reservoir quality of the Upper Cretaceous Austin Chalk Group and evaluation of reservoir-quality analysis methods; northern onshore Gulf of Mexico, U.S.A.

Production from the argillaceous Austin Chalk reservoirs from the Gulf of Mexico Basin is predominately from natural fractures, with some production from tight matrix. To understand Austin Chalk matrix reservoir quality, a database containing 1492 porosity and permeability analyses from 21 wells ranging from South Texas to central Louisiana was constructed. The depositional environment of the chalk is interpreted to have been a deeper-water (below storm wave base) setting on a drowned shelf where bottom waters and sediments varied between oxic and anoxic. Five lithofacies were reviewed where the in-place lithofacies are shown to have a strong effect on reservoir quality. Burrowed marly chalk (lithofacies 1) has the best reservoir quality, with a mean porosity of 6.2% and a geometric mean permeability of 351 nd. Burrowed chalky marl to marly chalk (lithofacies 2) has the second-best reservoir quality, with mean porosity being 5.5% and geometric mean permeability being 214 nd. Slightly burrowed laminated marly chalk (lithofacies 3) has a mean porosity of 4.5% and a geometric mean permeability of 101 nd. Well-laminated chalky marl to marly chalk (lithofacies 4) has the poorest reservoir quality, with a mean porosity of 3.5% and geometric mean permeability of 25 nd. Three measurement methods were used to calculate porosity and permeability: (1) routine core plug (RCP) analysis, (2) Gas Research Institute crushed rock (GRI) analysis, and (3) modified gas expansion (MGE) analysis. Comparison among these methods showed that the RCP method provided anomalously high permeabilities and relatively low porosities. The GRI method yielded moderately high permeabilities but expected porosity measurements. The MGE method appears to produce the best results, giving permeabilities measured down to low-single-digit nanodarcy values and the expected range of porosity. The MGE method also displayed the best correlation between porosity and permeability. The concepts from this study can be applied to other chalks worldwide.

Dinámica del empleo en sectores intensivos en uso del conocimiento en la Megalópolis del Valle de México, 2014-2018

Qualified human capital is key to the progress of cities. The objective of this work is to answer the following questions: how much, where, in which sectors, when, and why did employment change in knowledge-intensive sectors (KIS) in the Megalopolitan Region of the Valley of Mexico, its main cities, and in its municipalities? This Megalopolis is the main engine of national development. It is necessary to understand the dynamics of the Megalopolitan KIS employment, to take advantage of its positive effects, and prevent negative ones. The analysis period is 2014-2018: it covers the last section of the Free Trade Agreement between Mexico, the United States, and Canada, before the modifications negotiated in 2019, and almost a whole period of the federal government. The method is Spatial-Shift Share Analysis (SSS). It was possible to identify ascending territories, and others in dramatic decline. We translate the SSS concepts into causes of employment change, measure the changes at three spatial scales (megalopolitan, metropolitan and micro-spaces), and linked the changes to specific companies and products, in particular territories and sectors.

Producción capitalista del espacio en la Zona metropolitana del Valle de México, una aproximación conceptual

This paper presents a conceptual approach to the study of the urbanization process in the Metropolitan Area of Valley of Mexico (ZMVM), from the perspective of the social production of space and its capitalist appropriation. The aim is to contribute to the understanding of the problems derived from the expansion and metropolitan urbanization of Mexico City, among which the precarious living conditions of the population integrated to the metropolitan area stand out, as the expression of the contradictions inherent in the social production of space in capitalism. For the research, a mixed methodology was used to combined classical theoretical sources with the empirical reference gathered in documentary sources and field observations; offers a historical perspective and an interdisciplinary effort. The main contribution of the article is to underline the contradictory nature of the metropolitan expansion process and the continued subordination of rural space to urban dynamics. It concludes by highlighting the possibility and need to strengthen forms of social production of space focused on the reproduction of life rather than the reproduction of capital.

Applying convolutional neural networks to identify lithofacies of large-n cores from the Permian Basin and Gulf of Mexico: The importance of the quantity and quality of training data

Convolutional neural networks (CNNs), one of the most widely employed deep learning techniques, have achieved great success in image recognition. However, few attempts have been made in sedimentary studies, partially because it is challenging to generate a large-scale training database for sedimentary data. We compile ~32,000 images with interpreted facies from ~3200 ft (~1000 m) of cores from the Permian Basin and Gulf of Mexico. This database is used to train and evaluate a CNN model predicting the facies from core images. The best learned model achieves 83% accuracy when evaluated by the independent testing data. More importantly, we analyze the impacts of sample sizes on the prediction accuracy to understand how many samples is needed for a model to return satisfied performance. Accuracy does increase as sample number increases but even the learned model trained by 1% of available data (n = 300) can return 70% accuracy. This result suggests the deep learning model is able to provide fast sedimentary analysis and accelerate the core description processes with small amounts of training dataset. We also show that the model trained from the Permian Basin data set fails to predict the facies of the Gulf of Mexico cores because the two data sets are in different depositional environments. Therefore, a high-quality training database covering different depositional environments is critical in applying artificial intelligence in facies detection. This study suggests the model trained by small amounts of high quality data can aid human interpretation. It can efficiently provide basic information such as bed thickness, lithology, and net-to-gross ratio to free up geologists to conduct more complex tasks such as interpreting depositional environments.

Hydro-geochemistry-based appraisal of summer-season groundwater from three different semi-arid basins of northeast Mexico for drinking and irrigation

Hydro-geochemistry-based appraisal of summer-season groundwater from three different semi-arid basins of northeast Mexico for drinking and irrigation

Water consumption practices in university campuses. The experience of the National Autonomous University of Mexico

Abstract The Water Network of the National Autonomous University of Mexico (Red del Agua UNAM) and the Program for the Management, Use, and Reuse of Water in UNAM (PUMAGUA) carried out a survey with the aim of knowing the water consumption practices of the university community in its campuses located in the Metropolitan Area of the Valley of Mexico. A sample of 2,095 students, academics, administrative and support staff participated in this survey. The results show that 74% of the sample consume bottled water and that their average spending is between 0.50 and 1 dollar per day (11 to 20 Mexican pesos). The rates of bottled water consumption contrasts with the perception about water quality, since only 13% consider water quality distributed in the water fountains located within university campuses as ‘poor’ or ‘very poor’. The rates of bottled water consumption among university community are similar to the ones reported by studies in Mexico City and in Mexico as a whole, even though UNAM has a Water Observatory that allows people to know in real time water quantity and quality in university campuses.

Environmental Conditions Associated with Occurrences of the Threatened Yaqui Catfish in the Yaqui River Basin, Mexico

AbstractThe Yaqui Catfish Ictalurus pricei is an understudied species, with limited information available on its ecology, distribution, and local habitat use. Native to the southwestern United States and northwestern Mexico, Yaqui Catfish populations are declining, which has prompted listing of the species as threatened in the United States and as a species of concern in Mexico. Water overallocation, habitat degradation, invasive species introductions, and hybridization with nonnative Channel Catfish I. punctatus have caused the populations in Mexico to decline. The United States population collapsed after years of low recruitment. To better focus conservation efforts as well as define habitat associated with Yaqui Catfish occurrences, we assessed the distribution in the Yaqui River basin of Mexico by using historical data at a landscape scale. Yaqui Catfish were historically found across the watershed among a diversity of environments but were most frequently associated with small, intermittent streams. Basin land cover was dominated by forest, shrubland, and grassland, and Yaqui Catfish generally occurred in stream segments at similar proportions. However, a small number of Yaqui Catfish occurrences were associated with urban and cropland land cover types in proportions greater than the availability of those categories on the landscape. With the species facing declines in the region, this work will help to inform future conservation efforts aimed at securing the Yaqui Catfish, protecting suitable habitat, and better defining its current status in Mexico.

Description of the cumulative incidence of COVID-19 in the 10 cities of Mexico with most accumulated cases after 120 days of the first confirmed case

Background: The COVID-19 is potentially severe acute respiratory infectious disease, increasing day by day. The cumulative incidence of coronavirus disease (COVID-19) cases is showing similar trends in the globally confirming that, while at a different stage depending on the country, the COVID-19 pandemic has progressed rapidly in all countries. In this study, we evaluate the cumulative incidence of COVID-19 in 10 cities located in all regions of Mexico. Material and methods: Confirmed COVID-19 cases were obtained from the Government of Mexico’s open data portal. A listing of the metropolitan zones with most cases was built. Results: At the time of the data cut-off point, COVID-19 confirmed cases in the Valle de Mexico metropolitan area are more than 233 000, with a cumulative incidence of 183 cases/100 000 habitants. Even though Valle de Mexico has the highest reported number of cases, it is Villahermosa city which has the highest cumulative incidence with 647 cases/100 000 habitants. Conclusions: The estimation of cases through the Sentinel model has shown that, the real extension of the epidemic could be at least 8 times higher that official data; a situation that would place Mexico as one of the most affected countries in Latin America.

Urban-Induced Changes on Local Circulation in Complex Terrain: Central Mexico Basin

Land use land cover (LULC) significantly impacts local circulation in the Mexico Basin, particularly wind field circulations such as gap winds, convergence lines, and thermally induced upslope/downslope wind. A case study with a high-pressure system over the Mexico Basin isolates the influence of large-scale synoptic forcing. Numerical simulations reveal a wind system composed of meridional circulation and a zonal component. Thermal pressure gradients between the Mexico basin and its colder surroundings create near-surface convergence lines as part of the meridional circulation. Experiments show that the intensity and organization of meridional circulations and downslope winds increase when LULC changes from natural and cultivated land to urban. Zonal circulation exhibits a typical circulation pattern with the upslope flow and descending motion in the middle of the basin. Large values of moist static energy are near the surface where air parcels pick up energy from the surface either as fluxes of enthalpy or latent heat. Surface heat fluxes and stored energy in the ground are drivers of local circulation, which is more evident in zonal circulation patterns.

Bus fleet selection analysis for a BRT concession in the Mexico valley metropolitan zone

The present paper addresses the problem of determining the bus fleet composition (size and mix) for a Bus Rapid Transit (BRT) transportation service, where revenue, demand, and passenger-km index are considered for a sensitivity analysis. The proposed method relies on financial engineering methods to produce several cost and income inputs over time by applying Net Present Value (NPV) concepts. The sensitivity analysis is developed by solving different instances with a mixed-integer linear programming (MILP) model structured as an investment selection problem. The model is capable of determining the optimal size and mix selection under relevant operational requirements as restrictions. The method is applied for a case study in Mexico Valley Metropolitan Zone (MVMZ), illustrating the valuable insights obtained with the sensitivity analysis (response surface exploration) and providing the set of potential solutions and their estimated financial and operational outcomes, information that is relevant for potential operators to endorse a discussion and negotiation with the government authorities (concessioners).

Stability of the Fault Systems That Host-Induced Earthquakes in the Delaware Basin of West Texas and Southeast New Mexico

Abstract The Delaware basin of west Texas and southeast New Mexico has experienced elevated earthquake rates linked spatiotemporally to unconventional petroleum operations. Limited knowledge of subsurface faults, the in situ geomechanical state, and the exact way in which petroleum operations have affected pore pressure (Pp) and stress state at depth makes causative assessment difficult, and the actions required for mitigation uncertain. To advance both goals, we integrate comprehensive regional fault interpretations, deterministic fault-slip potential (DFSP), and multiple earthquake catalogs to assess specifically how faults of two systems—deeper basement-rooted (BR) and shallow normal (SN)—can be made to slip as Pp is elevated. In their natural state, the overall population faults in both the systems have relatively stable DFSP, which explains the low earthquake rate prior to human inducement. BR faults with naturally unstable DFSP and associated earthquake sequences are few but include the Culberson–Mentone earthquake zone, which is near areas of wastewater injection into strata above basement. As a system, the SN faults in the southcentral Delaware basin are uniformly susceptible to slip with small increases in Pp. Many earthquakes sequences have occurred along these shallow faults in association with elevated Pp from shallow wastewater injection and hydraulic fracturing. Our new maps and methods can be used to better plan and regulate petroleum operations to avoid fault rupture.