Soil moisture content and maize grain yield under conventional and conservation agriculture practices - results of short term field tests in liselo, Namibia

Christian Thierfelder (2023, [Artículo])

This article focuses on the results from trials developed to monitor the short-term effects of conventionally tilled systems versus CA on soil quality and crop productivity under conditions of the major cropping systems in central, north-central and north-eastern regions of Namibia. Conventional tillage (CT), Minimum tillage (MT), Minimum tillage, mulch (MT-M), Minimum tillage, rotation (MT-R) and Minimum tillage, mulch and rotation (MT-MR) were the primary treatments tested. Significant differences (p≤0.000) among the treatments were observed in the 0-60 cm soil profiles where MT-M plots had the highest soil moisture content (39.8 mm, Standard Error of Mean 0.2815) over the study period. A significant difference (p=0.0206) in grain yield was observed in the second season with CT plots yielding the highest grain yield (3852.3 kg ha-1, standard error of mean 240.35). Results suggest that CA has the potential to increase water conservation and contribute to reduction of the risk of crop failure. Climate change driven degradation under conventional tillage necessitate alternative sustainable tillage methods. Conservation tillage methods and conservation agricultural practices that minimize soil disturbance while maintaining soil cover need to be adopted more locally as viable alternatives to conventional tillage.

Grain Yield Soil Moisture Content CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CONSERVATION AGRICULTURE CONVENTIONAL TILLAGE GRAIN YIELDS SOIL WATER CONTENT MAIZE

Historical use of water resources. Civil works evolution in Zacatecas state

Carlos Bautista-Capetillo Georgia González-Pérez Hiram Badillo-Almaraz (2021, [Artículo, Artículo])

Availability and demand are essential aspects for the human being when planning is made to provide water to the different sectors that may have need of it; still, the demand of suitable volume of water increases day by day, while the supply decreases gradually. In this inverse relationship, anthropogenic and environmental dynamics are decisive to guarantee the needs of the population, specifically due to the climatic transformations evidenced in recent decades. Throughout history, the state of Zacatecas has suffered the ravages of extreme environmental events, mainly those related to drought. Likewise, but on a lesser extent, severe floods have occurred that have caused socioeconomic damage. In this work, the climatic variations of temperature and precipitation and their influence on the evolution of hydraulic systems for the supply of drinking water in the municipality of Nochistlán de Mejía, Zacatecas are analyzed during the period 1930-2015.

drinking water supply historical development of waterworks climate and its transformations Abasto de agua potable desarrollo histórico de obras hidráulicas clima y sus transformaciones CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA

Low thermal conductivity solar domestic water heater

MIGUEL ANGEL PORTA GANDARA JOSE LUIS FERNANDEZ ZAYAS JUAN FRANCISCO VILLA MEDINA NORBERTO CHARGOY DEL VALLE (2022, [Artículo])

"Solar domestic water heaters (SWH) with thermosyphon circulation are the most common commercial applications of solar energy in Mexico. They are also becoming popular in the rest of the world, given their simplicity, good economic returns, and sustainability. Traditionally the solar collector, the piping, and the storage tank are built of copper and steel. However, wáter quality in many parts of the Mexican Northwest has high mineral contents and, when heated, results in early metal pitting corrosion of SWH parts. Short-lived water heaters are bad promoters of the technology. In this work, a SWH thermoplastic Chlorinated Polyvinyl Chloride (CPVC) is built and tested under real operating conditions in La Paz, BCS, Mexico. The optimal design is detected with the aid of a suitable numerical model. Results reveal that a full SWH-CPVC can be technically and economically convenient for the weather conditions of the Northwestern states of Mexico."

Low thermal conductivity solar water heater CPVC solar water heater Solar water heater cooper pitting corrosion Thermosiphon circulation INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS TECNOLOGÍA ELECTRÓNICA DISPOSITIVOS TERMOELÉCTRICOS DISPOSITIVOS TERMOELÉCTRICOS

Agricultura, agua y cambio climático en zonas áridas de México

SALVADOR EMILIO LLUCH COTA JUAN ALBERTO VELAZQUEZ ZAPATA César Nieto Delgado (2022, [Artículo])

"En este artículo se expone cómo a pesar de que la ciencia y la tecnología han permitido aumentar históricamente la productividad agrícola, hoy día existen grandes retos derivados del cambio climático y la crisis global de abastecimiento de agua. Se comentan algunas medidas de adaptación y manejo del recurso agua, con algunas referencias a nuestra realidad nacional, y se argumenta cómo el enfoque de Nexo, que implica la toma de decisiones sobre el uso del recurso agua de forma transectorial, representa una alternativa de adaptación al cambio climático."

Cambio climático, agricultura, agua, Nexo, adaptación Climate change, agriculture, water, nexus, adaptation CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO CLIMATOLOGÍA CLIMATOLOGÍA REGIONAL CLIMATOLOGÍA REGIONAL

Waterhole detection using a vegetation index in desert bighorn sheep (Ovis canadensis cremnobates) habitat

Jonathan Gabriel Escobar Flores (2019, [Artículo])

In arid ecosystems, desert bighorn sheep are dependent on natural waterholes, particularly in summer when forage is scarce and environmental temperatures are high. To detect waterholes in Sierra Santa Isabel, which is the largest area of desert bighorn sheep habitat in the state of Baja California, Mexico, we used the normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) from Sentinel-2 satellite images. Waterhole detection was based on the premise that sites with greater water availability, where NDVI was higher, can be identified by their density of vegetation greenness. For the detected waterholes, we estimated the escape terrain (presence of cliffs or steep, rocky slopes) around each by the vector ruggedness measure to determine their potential use by desert bighorn sheep based on the animals’ presence as documented by camera traps. We detected 14 waterholes with the NDVI of which 11 were known by land owners and 3 were unrecorded. Desert bighorn were not detected in waterholes with high values of escape terrain, i.e., flat areas. Waterhole detection by NDVI is a simple method, and with the assistance and knowledge of the inhabitants of the Sierra, it was possible to confirm the presence each waterhole in the field. © 2019 Escobar-Flores et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Article, bighorn sheep, environmental aspects and related phenomena, environmental parameters, habitat, Mexico, nonhuman, normalized difference vegetation index, normalized difference water index, water availability, waterhole, animal, bighorn sheep, CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS CIENCIA FORESTAL CIENCIA FORESTAL

Utilización de aguajes por el borrego cimarrón (Ovis canadensis cremnobates) y análisis de calidad del agua en Sierra Santa Isabel, Baja California, México

Watering sites use by bighorn sheep (Ovis canadensis cremnobates) and water quality analysis in Sierra Santa Isabel, Baja California, Mexico

Jonathan Gabriel Escobar Flores SERGIO ALVAREZ CARDENAS Sara Cecilia Díaz Castro Aradit Castellanos Vera Jorge Torres Rodriguez MARIANA DELGADO FERNANDEZ (2016, [Artículo])

"Se analizó la utilización de aguajes por el borrego cimarrón en la Sierra Santa Isabel, Baja California, México durante la temporada de sequía de 2011 y 2013 y el periodo de lluvias e inicio de la temporada de sequía del 2015. Asimismo, se estudió la calidad del agua, con base en siete parámetros fisicoquímicos. Se obtuvieron 260 registros fotográficos de borregos cimarrones, donde hembras, añeros y corderos representaron el 73%. En el periodo de lluvias, en dos de los aguajes se obtuvieron valores de conductividad de 1.31 µS/cm2 y 1.92 µS/cm2, y de sólidos disueltos totales de l0.65 ppt y 0.95 ppt, indicando un bajo contenido de sales en el agua. Los valores de oxígeno disuelto mayores a 6.4 ppm, dureza del agua menor a 100 ppm y PH entre 6.5 y 8.5, sugieren que el agua tiene condiciones óptimas para ser bebida por los borregos cimarrones. Los aguajes con mayor utilización por los borregos fueron El Zamora (n = 120) y El Cordero (n = 67), donde se registraron las mejores condiciones de calidad de agua en este estudio. El mayor registro de hembras y añeros, asociado a condiciones óptimas de calidad del agua, confirman la importancia de los aguajes para la crianza y reclutamiento del borrego cimarrón."

"Water used by bighorn sheep during the 2011 and 2013 dry seasons and the rainy season and drought of 2015 in the Sierra Santa Isabel of the State of Baja California, Mexico was analyzed for seven physicochemical parameters. At four watering sites, 260 photographs of sheep were obtained. Females, yearlings, and lambs accounted for 73% of the photographs. In the rainy season at two watering sites, conductivity was 1.31 µS/cm2 and 1.92 µS/cm2 and total dissolved solids was 0.65 and 0.95 ppt, indicating low salt content and safe for bighorn sheep. The watering sites with greater use by bighorn sheep were El Zamora (n = 120) and El Cordero (n = 67), which also had the best water quality. The frequent use by females and yearlings of the two sites with optimal water quality support the belief that watering sites for lambing and recruitment of bighorn sheep is important."

Baja California, borrego cimarrón, calidad del agua, cámaras trampa. Baja California, bighorn sheep, water quality, camera traps. BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA ANIMAL (ZOOLOGÍA) MAMÍFEROS MAMÍFEROS

Evaluación de la intrusión salina utilizando el método electromagnético transitorio (TEM) y análisis de iones mayores e isótopos estables del agua en el acuífero La Misión, B.C., México

Saline intrusion assessment using transient electromagnetic method (TEM) and analysis of major ions and stable isotopes of water in La Mision aquifer, B.C., Mexico

Yesica Guadalupe Cabrera Sillas (2023, [Tesis de maestría])

El acuífero La Misión constituye una fuente importante de abastecimiento de agua en la zona semiárida de Ensenada, Baja California, México. La explotación intensiva del acuífero puede haber desarrollado el deterioro de la calidad del agua subterránea, y con ello el avance del agua de mar. El presente estudio se centra en la evaluación de la posible intrusión salina en el acuífero costero La Misión a partir de técnicas geofísicas e hidrogeoquímicas. De acuerdo con investigaciones anteriores, se plantea la hipótesis de que el acuífero está afectado por procesos de mezcla de agua de mar principalmente en la franja costera. El estudio geofísico comprende 11 sondeos Transitorios Electromagnéticos (TEM). Además, se recolectaron 18 muestras de agua subterránea en temporada de secas y lluvias, donde se analizaron isótopos estables (δ18O y δ2H) y los principales iones mayores (Na+, K+, Ca2+, Mg2+, Cl-, HCO3, CO32- y SO42-). La inversión de datos geofísicos en 1D revela dos acuíferos en la zona de estudio; 1) el acuífero de depósitos de arena aluvial saturado superficial con un rango de resistividad de 2.1-5.5 Ωm y un espesor <80 m (UH2); 2) el segundo pertenece a un acuífero semiconfinado compuesto por limolitas y areniscas con resistividades de 13.8 a 21.4 Ωm (UH4). Los resultados hidroquímicos muestran que los principales tipos de aguas subterráneas son Ca-Cl, mixtas y Na-Cl. Además, las diversas relaciones iónicas confirmaron el proceso de intercambio iónico inverso donde el Ca2+ y el Mg2+ en la matriz del acuífero se han reemplazado por Na+ en sitios favorables. El cálculo del índice de saturación de minerales indica que las muestras de agua subterránea están saturadas con respecto a los minerales de carbonato. Por lo tanto, estos resultados sugieren que el acuífero costero La Misión está sujeto a la influencia continua de la mezcla de agua de mar, disolución de minerales carbonatados ayudado por la interacción agua-roca, y los procesos de intercambio iónico. Considerando que éstos son los factores determinantes que están controlando la evolución del agua subterránea en esta zona.

The Misión aquifer is an important source of water supply in the semi-arid zone of Ensenada, Baja California, Mexico. Intensive exploitation of the aquifer may have developed groundwater quality deterioration, and the advance of seawater. The present study focuses on the evaluation of possible saline intrusion in the coastal aquifer of La Misión, using geophysical and hydrogeochemical techniques. Based on previous research, it is hypothesized that the aquifer is affected by seawater mixing processes mainly in the coastal strip. The geophysical survey comprises 11 Transient Electromagnetic soundings (TEM). In addition, a total of 18 groundwater samples were collected in dry and post rainy season, where stable isotopes (δ18O and δ2H) and the main major ions (Na+, K+, Ca2+, Mg2+, and Cl-, HCO3-, CO32- and SO42-) were analyzed. One-dimensional inversion geophysical data reveals two aquifers in the study area. 1) the shallow saturated alluvial sand deposit aquifer with a resistivity range of 2.1-5.5 Ωm and a thickness <80 m (UH2). 2) the second belongs to a semi-confined aquifer composed of siltstones and sandstones with resistivities of 13.8 to 21.4 Ωm (UH4). Hydrochemical results show that the main groundwater types are Ca-Cl, mixed and Na-Cl. In addition, the various ionic ratios confirmed the reverse ion exchange process where Ca2+ and Mg2+ in the aquifer matrix have been replaced by Na+ at favorable sites. Calculation of the mineral saturation index indicates that the groundwater samples are saturated with respect to carbonate minerals. Therefore, these results suggest that the coastal Mission aquifer is subject to the continuous influence of seawater mix, dissolution of carbonate minerals aided by water-rock interaction, and ion exchange processes. Considering these processes, the important determining factors that are controlling the evolution of groundwater in this zone.

Agua subterránea, resistividad, interacción agua-roca, índice de saturación, salinidad. Groundwater, resistivity, water-rock interaction, saturation index, salinity. CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOFÍSICA GEOMAGNETISMO Y PROSPECCIÓN MAGNÉTICA GEOMAGNETISMO Y PROSPECCIÓN MAGNÉTICA

Freshwater exchanges and surface salinity in the Colombian basin, Caribbean Sea

Emilio Beier (2017, [Artículo])

Despite the heavy regional rainfall and considerable discharge of many rivers into the Colombian Basin, there have been few detailed studies about the dilution of Caribbean Surface Water and the variability of salinity in the southwestern Caribbean. An analysis of the precipitation, evaporation and runoff in relation to the climate variability demonstrates that although the salt balance in the Colombian Basin overall is in equilibrium, the area south of 12N is an important dilution sub-basin. In the southwest of the basin, in the region of the Panama-Colombia Gyre, Caribbean Sea Water is diluted by precipitation and runoff year round, while in the northeast, off La Guajira, its salinity increases from December to May by upwelling. At the interannual scale, continental runoff is related to El Niño Southern Oscillation, and precipitation and evaporation south of 12°N are related to the Caribbean Low Level Jet. During El Niño years the maximum salinification occurs in the dry season (December-February) while in La Niña years the maximum dilution (or freshening), reaching La Guajira Coastal Zone, occurs in the wet season (September-November). © 2017 Beier et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

sea water, fresh water, Article, Caribbean, dilution, dry season, El Nino, environmental parameters, evaporation, freshwater exchange, geographic distribution, molecular weight, oscillation, precipitation, river basin, salinity, seasonal variation, s CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO OCEANOGRAFÍA OCEANOGRAFÍA

Dipole-wind interactions under gap wind jet conditions in the Gulf of Tehuantepec, Mexico: A surface drifter and satellite database analysis

MAURO WILFRIDO SANTIAGO GARCIA (2019, [Artículo])

Gap wind jets (Tehuano winds) trigger supersquirts of colder water and mesoscale asymmetric dipoles in the Gulf of Tehuantepec (GT). However, the effects of successive gap wind jets on dipoles and their effects inside eddies have not yet been studied. Based on the wind fields, geostrophic currents, and surface drifter dispersion, this research documented three dipoles triggered and modified by Tehuano winds. Once a dipole develops, successive gap wind jets strengthen the vortices, and the anticyclonic eddy migrates southwestward while the cyclonic eddy is maintained on the east side of the GT. During the wind relaxation stage, the cyclonic eddy may propagate westward, but due to the subsequent re-intensification of the Tehuano winds, the vortex could break down, as was suggested by surface drifter dispersion pattern and geostrophic field data. The effect of the Tehuano winds was evaluating via eddy-Ekman pumping. Under Tehuano wind conditions, Ekman downwelling (upwelling) inside the anticyclonic (cyclonic) eddies may reach ~ -2.0 (0.5) m d-1 and decrease as the wind weakens. In the absence of Tehuano winds, Ekman downwelling inside the anticyclonic eddy was ~ 0.1 (-0.1) m d-1. The asymmetry of downwelling and upwelling inside eddies during Tehuano wind events may be associated with Tehuano wind forcing. © 2019 Santiago-García et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

article, dipole, leisure, Mexico, cold, ecosystem, factual database, geographic mapping, hurricane, Mexico, satellite imagery, season, water flow, wind, sea water, Cold Temperature, Cyclonic Storms, Databases, Factual, Ecosystem, Geographic Mapping, CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO OCEANOGRAFÍA OCEANOGRAFÍA

Maintenance of Coastal Surface Blooms by Surface Temperature Stratification and Wind Drift

MARY CARMEN RUIZ DE LA TORRE (2013, [Artículo])

Algae blooms are an increasingly recurrent phenomenon of potentially socio-economic impact in coastal waters globally and in the coastal upwelling region off northern Baja California, Mexico. In coastal upwelling areas the diurnal wind pattern is directed towards the coast during the day. We regularly found positive Near Surface Temperature Stratification (NSTS), the resulting density stratification is expected to reduce the frictional coupling of the surface layer from deeper waters and allow for its more efficient wind transport. We propose that the net transport of the top layer of approximately 2.7 kilometers per day towards the coast helps maintain surface blooms of slow growing dinoflagellate such as Lingulodinium polyedrum. We measured: near surface stratification with a free-rising CTD profiler, trajectories of drifter buoys with attached thermographs, wind speed and direction, velocity profiles via an Acoustic Doppler Current Profiler, Chlorophyll and cell concentration from water samples and vertical migration using sediment traps. The ADCP and drifter data agree and show noticeable current shear within the first meters of the surface where temperature stratification and high cell densities of L. polyedrum were found during the day. Drifters with 1m depth drogue moved towards the shore, whereas drifters at 3 and 5 m depth showed trajectories parallel or away from shore. A small part of the surface population migrated down to the sea floor during night thus reducing horizontal dispersion. The persistent transport of the surface bloom population towards shore should help maintain the bloom in favorable environmental conditions with high nutrients, but also increasing the potential socioeconomic impact of the blooms. The coast wise transport is not limited to blooms but includes all dissolved and particulate constituents in surface waters. © 2013 Ruiz-de la Torre et al.

chlorophyll, algal bloom, article, cell count, cell density, coastal waters, controlled study, dinoflagellate, Lingulodinium polyedrum, meteorological phenomena, Mexico, near surface temperature stratification, nonhuman, nutrient concentration, popul CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO OCEANOGRAFÍA OCEANOGRAFÍA