Wadi Research Articles

Hiroaki Shimokawa.

Hiroaki Shimokawa.

Exploitation of some raw minerals for Increasing productivity of ordinary portland cement.

This study aims to utilize a local natural mineral material from different places in western area of Saudi Arabia namely, (Osfan, Alkamel, Wadi starah, Khulais, Jeddah and Alghowla) as a partial replacement of ordinary portland cement (OPC) in order to increase the productivity of ordinary portland cement (OPC), minimizing the problems associated with its industry involving energy consumption and air pollution. In addition to the reference sample (C:100% wt. OPC), other six mixes were prepared from 75% wt. of OPC and 25 wt. %) of each raw mineral, they are denoted as (C1, C2, C3, C4, C5 and C6). Different cementing, sintering, chemical and mechanical properties of the prepared mixes were tested according to the international standard specifications. It was concluded that OPC blended with 25 wt.% of local natural minerals from Jeddah (C5), Wadi starah (C3) and Alkamel C2 show outstanding cementing and mechanical properties compared with the reference sample. They recorded relatively longer setting time ranges from (55-160, 52-145, 52-144) minutes compared with the reference sample (C) which recorded only (48-120) minutes, relatively higher percent of combined water at different ages of hydration (23.75-28.23, 20.84-24.59, 16.34-19.31%),respectively whereas the reference sample (C) recorded (15.59-18,00 %), higher heat of hydration (81-97, 77-94, 75-90 cal/g), respectively compared with reference sample which recorded (70- 85 cal/g ), higher bulk density (1.61-1.96, 1.66-1.84, 1.65-1.84 g/cm 3 ), respectively compared with the reference sample that recorded (1.61-1.84 g/cm3), lower apparent porosity (15.02-10.41, 16.25-12.75, 17.40-13.96%), respectively whereas the reference sample noted (24.11-14.39%) and relatively higher values of compressive strength (90-125, 80-120, 75-113 kg/cm 2 ), respectively compared with the reference sample which recorded (60-110 kg/cm 2 ). The remaining samples C1, C4 and C6 showed less cementing and mechanical properties compared with the reference sample (C). The improved properties of C5, C3 and C2 are due to their relatively higher content of portlandite mineral (Ca(OH 2 )) one of the main hydration of cement, as well as their relatively better microstructure.

A global analysis of terrestrial plant litter dynamics in non-perennial waterways

Perennial rivers and streams make a disproportionate contribution to global carbon (C) cycling. However, the contribution of intermittent rivers and ephemeral streams (IRES), which sometimes cease to flow and can dry completely, is largely ignored although they represent over half the global river network. Substantial amounts of terrestrial plant litter (TPL) accumulate in dry riverbeds and, upon rewetting, this material can undergo rapid microbial processing. We present the results of a global research collaboration that collected and analysed TPL from 212 dry riverbeds across major environmental gradients and climate zones. We assessed litter decomposability by quantifying the litter carbon-to-nitrogen ratio and oxygen (O2) consumption in standardized assays and estimated the potential short-term CO2 emissions during rewetting events. Aridity, cover of riparian vegetation, channel width and dry-phase duration explained most variability in the quantity and decomposability of plant litter in IRES. Our estimates indicate that a single pulse of CO2 emission upon litter rewetting contributes up to 10% of the daily CO2 emission from perennial rivers and stream, particularly in temperate climates. This indicates that the contributions of IRES should be included in global C-cycling assessments.

Characterization of the Capibaribe River Dry Bed with Ground Penetrating Radar (GPR)

ABSTRACT For an adequate hydrogeological study of alluvial layers in the semi-arid zone, it is important to know well its geometry and its hydraulics characteristics. Alluvial formations are generally constituted by erosion, transport and sedimentation processes, causing considerable heterogeneity in soil hydraulic parameters and water flow. The present research had as objective to perform a geophysical characterization using the Ground Penetrating Radar – GPR in the dry bed of the Capibaribe river. To the extent that depositional layers exhibit changes in water content, granularity, sediment type and layer orientation, the water table as well as sedimentary structures and lithological contacts tend to be identified, making the method effective for hydrogeology research. The study area comprises alluvial dry river bed of upper Capibaribe river in the municipality of Santa Cruz do Capibaribe. The results showed that GPR was efficient in the imaging of the subsurface contributing to the knowledge of the geometry and the stratigraphy of the aquifer of the dry bed of the river. In the dry bed of the river, with 400 MHz antenna the signal reached a depth of 2.65 m, and with the antenna of 200 MHz, the signal reached a depth of 6.00 m. The capillary fringe was identified at a depth of 3.0m with the use of 200MHz and 400MHz antennas.

Relação peso-comprimento de duas espécies de peixes em um rio intermitente no nordeste do Brasil

Given the context of high hydrological uncertainties and stress in dryland streams, the evaluation of length-weight relationships and condition factors of fish becomes of chief concern for the understanding of these systems. Length-weight relationships were estimated for two fish species, Astyanax fasciatus (Cuvier 1819) and Astyanax bimaculatus (Linnaeus 1758), from temporary pools in a dry river bed. Length-weight relationship information was compared between dry and rainy seasons. Sampling was performed using gillnets, manual trawls and cast nets at different reaches of the river. Estimates for the values of b of the length-weight relationship were 2.63 for A. fasciatus, and 2.78 for A. bimaculatus, indicating a negative allometric growth. The condition factor ranged between 0.0180 and 0.0187 for both species, without significant difference between seasons, and meaning a greater investment in growth rather than weight gain. Results indicated that fishes tended to be larger during the rainy season, likely representing the result of a higher frequency of immature and smaller individuals during the previous dry season as a consequence of reproductive activity of adults. Keywords: Astyanax fasciatus, Astyanax bimaculatus, temporary pools, condition factor.

Ecological Value of the Sorokaoziorki Wetland Complex in the Steppe of Central Eurasia (Khakassia, Russian Federation)

The wetlands of Central Asia, including many of high ecological value, are poorly studied and poorly represented in international conservation activities. The Sorokaoziorki (“Forty Lakelets”) complex of wetlands, located in the arid Koibalskaya steppe (Republic of Khakassia, Russian Federation), falls into this category. We documented the origin of the complex’s wetlands, patterns of land use and economic activities, and use of the area by multiple bird, mammal, and fish species. The “lakelets” of the Sorokaoziorki originated from a dried river bed that refilled relatively recently with water introduced from irrigation activities. The resultant wetlands and surrounding wet grasslands within the Sorokaoziorki complex represent a refuge for wildlife, while the surrounding steppe has been turned to pasture. Located at a crossroads of bird flyways, at least 140 bird species use the Sorokaoziorki complex to nest or as a stop-over point during migration. Additionally, we documented the occurrence of seven fish, one lamprey, and seven mammal (including three bat) species within the complex. The planting of sea-buckthorn (Hippophaё rhamnoides) and the restriction of grazing around the edges of the wetlands in the Sorokaoziorki wetland complex has contributed to the conservation of this ecologically important area.

Organic contaminant removal efficiency of sodium bentonite/clay (BC) mixtures in high permeability regions utilizing reclaimed wastewater: A meso-scale study

Wastewater reclamation now represents an effective measure for sustainable water resource management in arid regions, however wastewater components (organic micropollutants) may potentially impact local ecological and/or human health. Previous studies have shown that sodium bentonite/natural clay (BC) mixes may be used to effectively reduce riverbed infiltration in regions characterized by excessively high hydraulic conductivity. Accordingly, the current study sought to investigate the contaminant removal efficiency (Re) of several BC mass ratios in simulated dry riverbeds. Results indicate that the measured Re of NH4+-N, CODcr and BOD5 increased in concurrence with an increasing sodium bentonite ratio, up to a maximum Re of 97.4% (NH4+-N), 55.2% (CODcr), and 51.5% (BOD5). The primary contaminant removal site was shown to be the infiltration-reducing (BC) layer, accounting for approximately 40%, 60%, and 70% of NH4+-N, CODcr and BOD5 removal, respectively. Conversely, the removal efficiency of NO3-N was found to be low (<15%), while total phosphorous (TP) was found to actively leach from the infiltration-reduction layer, resulting in measured TP discharges 2.4–4.8 times those of initial infiltration values. The current study provides a technical baseline for the efficacy of sodium bentonite as an effective bi-functional material in areas utilizing reclaimed water i.e. concurrent reduction of infiltration rates (Function 1) and decontamination of reclaimed wastewater infiltration/recharge (Function 2). Findings indicate that sodium bentonite-clay mixes may represent a feasible alternative for managing recharge of non-potable aquifers with reclaimed wastewater.

Puma (Puma concolor), a top predator in Sierra del Tentzo Nature Reserve in Central Mexico

The puma ( Puma concolor ) is the felid with the broadest distribution in America and plays a key role in the environment. However, there is scarce information about the species, as well as on how habitat loss, prey depletion and hunting have affected puma population along its range. Thus, it is imperative to generate information on the presence and distribution of puma in highly fragmented habitats like Central Mexico. We conducted a camera trapping survey to determine deer densities during September 2012 along trails in remnants of oak forest near the town of San Nicolas Huajuapan in the municipality of Huehuetlan el Grande, Puebla (18° 46ʹ 57.18ʺ N, -98° 07ʹ 18.95ʺ W). A photograph of an adult puma of undetermined sex was obtained at 00:32 hours on September 16 near a dry river bed at 1,680 masl. During the same season, we also captured other species like white tailed deer ( Odocoileus virginianus ), ringtail ( Bassariscus astutus ), coyote ( Canis latrans ) and grey fox ( Urocyon cinereoargenteus ). This record is important as the closest protected area presumably inhabited by puma is the Izta-Popo Nature Reserve; other sightings have also been recorded in the Mixteca Poblana and the Tehuacan-Cuicatlan Biosphere Reserve. This record is noteworthy because the species distribution in the state is unknown. A distance analysis showed that this site is relevant for connecting different puma populations in Central Mexico.

The Use Of Power Point Presentations To Motivate First Year Secondary School Students To Learn English : The Case Of Oued Taga Secondary School Batna

Cette etude vise a montrer comment motiver les etudiants de premiere annee secondaire a apprendre l’anglais a travers l’utilisation de l’une des T.I.C. (technologies d’information et de la communication), Power Point Presentations, dans le processus de l’enseignement et l’apprentissage durant le cycle secondaire. Son objectif est d’encourager et renforcer la motivation des etudiants en attirant leur attention sur cette technique qui a prouve son efficacite dans l’apprentissage de l’anglais comme langue etrangere. Pour atteindre cet objectif le chercheur nous avons opere d'une facon quasi experimentale. La problematique de cette etude releve le fait que la majorite des etudiants ne sont pas motive pour apprendre la langue anglaise. L’hypothese de cette etude stipule que si on enseigne l’anglais avec ces nouvelles techniques d’apprentissage (tel Power Point Presentations), les etudiants seront motives pour etudier cette langue etrangere. Un pre-test et un post-test, utilisent un group de 35 etudiants choisis au hasard parmi une population de 210 etudiants de premiere annee secondaire, filiere science, du lycee de Oued Taga a Batna.les instruments de recherche sont deux questionnaires pour les professeures et les etudiants, plus une observation comme complement d’investigation en classe. Les resultats obtenus sont calcules avec usage de SPSS 24. Ces resultats indiquent que les etudiants et leurs professeurs preferent cette nouvelle methode par rapport a l’ancienne. En conclusion, les resultats d’demontrent l’efficacite de cette technique pour l’ensemble des participants (etudiants et professeurs).

Characteristics of radiocesium contamination of dry riverbeds due to the Fukushima Daiichi Nuclear Power Plant accident assessed by airborne radiation monitoring

The Great East Japan Earthquake that occurred on 11 March 2011 generated a series of massive tsunami waves that caused severe damage to the Fukushima Daiichi Nuclear Power Plant, following which large amounts of radioactive materials were discharged from the power plant into the environment. Given the recently developed technologies for unmanned helicopters and their potential application in airborne radiation monitoring, we developed a radiation monitoring system for aerial use. We then used unmanned helicopters to measure the radiation level in areas with soil contaminated by radiocesium emitted from the nuclear power plant to evaluate the ambient dose rate distribution around the site. We found that in dry riverbeds downstream of the highly contaminated watershed, especially in the upstream parts, that the ambient dose rate was higher than that in protected inland areas. In addition, we carried out soil sampling in dry riverbeds. The soil sample data agreed with the results obtained from the unmanned helicopter. A possible scenario is that river sediment and adjacent soil containing radioactive materials were carried downstream due to an event such as a rise in water level caused by, e.g., a typhoon, and that these remained in the riverbed after the water drained away. The vertical profile of radiocesium in the soil and the measurements of river sediment at river mouth areas corroborated this scenario.

Assessing the ecological health of rivers when they are dry

Rivers and streams that dry up are found on every continent, and can form a large proportion of river networks. When rivers are dry, traditional indicators of river health – such as aquatic macroinvertebrates, fish or water quality – cannot be measured. Aquatic health indicators are widely used to assess wetted habitats, but currently no universally applicable indicators have been developed or applied to assess dry riverbed health. Dry riverbeds are often the ‘typical’ state of many intermittent rivers and streams; however, the ecological health of these habitats is rarely, if ever, assessed in monitoring programs. Resource managers have called for indicators of intermittent river health during the dry phase. The use of terrestrial invertebrate biota (e.g. ants, beetles, and spiders) as indicators in this study provides a novel solution to assessing rivers when they are dry.We developed a conceptual model of human-induced stressors (i.e. disturbance by livestock and feral mammals) on dry riverbed biota, which guided the selection of potential health indicators. Livestock and feral mammals are one of the most significant stressors on riverine ecosystems in Queensland, and impact riverbeds by altering the substrate through compaction, rooting and pugging. We trialled the use of metrics of terrestrial invertebrate assemblages as indicators of dry riverbed health in four Australian dryland catchments: Bulloo, Paroo, Warrego and Nebine. We used quantile regression and found that terrestrial invertebrate communities responded negatively (and significantly, p<0.05) to a gradient of disturbance, defined by on-the-ground field measurements of livestock and feral mammal impacts. This response to stressors was predicted by the initial conceptual model.We conclude that terrestrial invertebrates in this study are suitable indicators of dry riverbed health, as they are impacted by disturbance from livestock and feral mammals. They can be used in the same way that indicators, such as aquatic macroinvertebrates, are traditionally used to assess river health. We also successfully combined indicators of wet and dry habitats to provide a holistic assessment of the health of intermittent river ecosystems incorporating all sections of the river network. We suggest that this approach should be adopted by other river health monitoring programs in rivers around the world.

Diverse invertebrate fauna using dry sediment as a refuge in semi-arid and temperate Australian rivers

Dormant aquatic invertebrates can remain viable in riverbed sediment during dry phases, forming a source for recolonisation during wet periods. Regional differences in capacity for invertebrates to survive drying in this way are poorly understood, but may indicate regional differences in vulnerability to altered flow regimes. We compared diversity of invertebrates in dry sediment from intermittent rivers in temperate and semi-arid Australia after 4–8 weeks of drying. We predicted adaptations of semi-arid biota to severe and unpredictable drying would make dry sediment a more significant recolonisation source, with higher relative diversity when compared with temperate rivers. Emerging aquatic invertebrate assemblages were compared to those sampled in nearby pools, as a common drying refuge. Relative taxa richness in rehydrated sediments was higher in the semi-arid region (83 ± 16% of pool taxa) than the temperate (47 ± 6% of pool taxa), despite lower overall richness (24 taxa in semi-arid, 32 taxa in temperate). Semi-arid rivers had greater potential for dry riverbeds to act as a source for recolonisation, given high relative diversity and abundance in dry sediment, combined with the frequent absence of alternative refuges. However, dry riverbeds in both regions provided a significant short-term refuge for aquatic invertebrates.

Aeolian process of the dried-up riverbeds of the Hexi Corridor, China: a wind tunnel experiment.

Wind tunnel studies, which remain limited, are an important tool to understand the aeolian processes of dried-up riverbeds. The particle size, chemical composition, and the mineral contents of sediments arising from the dried river beds are poorly understood. Dried-up riverbeds cover a wide area in the Hexi Corridor, China, and comprise a complex synthesis of different land surfaces, including aeolian deposits, pavement surfaces, and Takyr crust. The results of the present wind tunnel experiment suggest that aeolian transport from the dried-up riverbeds of the Hexi Corridor ranges from 0 to 177.04g/m2/min and that dry riverbeds could be one of the main sources of dust emissions in this region. As soon as the wind velocity reaches 16m/s and assuming that there are abundant source materials available, aeolian transport intensity increases rapidly. The dried-up riverbed sediment and the associated aeolian transported material were composed mainly of fine and medium sands. However, the transported samples were coarser than the bed samples, because of the sorting effect of the aeolian processes on the sediment. The aeolian processes also led to regional elemental migration and mineral composition variations.

Water Issues in Chile: How Does a Dry River Sound?

This article examines the policies that have transformed water into a market commodity in Chile. Graciela Muñoz, an artist born and raised in one of the country’s areas affected by the drought produced by these policies, travelled to Chilean Patagonia to record the sound of the Baker River, and transferred its sounds to 28 small loudspeakers installed on the dry riverbed of the Petorca River, near her hometown. Through this soundscape, Muñoz temporarily recovered a lost experience where a river that does not exist anymore appears again, in sound, superimposing the past over a uncertain present.

A revision of the Afrotropical genus Prytanomyia Özdikmen, 2006 (Asilidae, Laphriinae)

The monotypic Afrotropical genus Prytanomyia Özdikmen, 2006 is revised. Laphystia kochi Lindner, 1973 is found to belong to Prytanomyia and is identical to Prytanomyia albida (Oldroyd, 1974), type of the genus. As a consequence L. kochi is newly combined with Prytanomyia, and P. albida is placed in the synonymy of P. kochi. The species inhabits arid environments, is restricted to the Namib desert from southern Angola to southern Namibia, and is found on vegetated sand mounds and dunes and in dry riverbeds. The highly reduced pulvilli, characteristic of this species, are believed to be an adaptation to living and perching on sandy surfaces.

Performance of PolSAR backscatter and PolInSAR coherence for scattering characterization of forest vegetation using single pass X-band spaceborne synthetic aperture radar data

Airborne synthetic aperture radar (SAR) data have been successfully used for forest height inversion; however, there is limited applicability in spaceborne scenarios due to high temporal decorrelation. This study investigates the potential of a high-resolution fully polarimetric interferometric pair of TerraSAR-X/TanDEM-X SAR data with no temporal decorrelation to analyze the backscatter and coherence response and to implement polarimetric SAR interferometry-based height inversion algorithms. The data were acquired over Barkot forest region of Uttarakhand state in India. Yamaguchi decomposition was implemented onto the dataset to express total backscatter as a sum of different scattering components from a single SAR resolution cell. Coherency matrix was used to compute complex coherence for different polarization channels. Forest areas suffered from low coherence due to volume decorrelation, whereas a dry river bed had shown high coherence. The coherence amplitude inversion approach overestimated the forest height and also resulted in false heights for this dry river bed. These limitations were overcome by implementing three-stage inversion modeling, which assumes polarization-independent volume coherence. The results were validated using ground truth data available for 49 plots, and the latter was found to be more accurate with an overall accuracy of 90.15% and root-mean-square error of 2.42 m.

The experimental flow to the Colorado River delta: Effects on carbon mobilization in a dry watercourse

AbstractHere we report on the effects of an experimental flood on the carbon cycling dynamics in the dry watercourse of the Colorado River in Mexico. We observed post‐flood differences in the degree of decay, age, and concentration of dissolved organic carbon (DOC), as well as dissolved CH4 and CO2 concentrations throughout the study site. Our results indicate that this flooded waterway was a limited source of CH4 and CO2 to the atmosphere during the event and that DOC age increased with time of flooding. Based on our findings, we suggest that the interplay between storage and mobilization of carbon and greenhouse gases in arid and semiarid regions is potentially sensitive to changing climate conditions, particularly hydrologic variability. Changes in the radiocarbon age of DOC throughout the flooding event suggest that organic matter (OM) that had been stored for long periods (e.g., millennial) was mobilized by the flooding event along with CO2. The OM residing in the dry riverbed that was mobilized into floodwaters had a signature reflective of degraded vascular plant OM and microbial biomass. Whether this microbial OM was living or dead, our findings support previous work in soils and natural waters showing that microbial OM can remain stable and stored in ecosystems for long time periods. As human appropriation of water resources continues to increase, the episodic drying and rewetting of once natural riverbeds and deltas may fundamentally alter the processing and storage of carbon in such systems.

Comparison of infiltration rates in the dry riverbed of the Colorado River Delta during environmental flows

Water has been over-allocated all over the world; natural rivers have been over-exploited and regulated to manage storage and distribute the water to thirsty cities and agricultural lands. The Colorado River is no exception to this trend. It is one of the most regulated rivers in the world; the once mighty Delta that formed from the river has become a few hectares of native trees surrounded by agriculture lands and houses. At the border between Mexico and the U.S., the last of the Colorado’s water is diverted, so that the last 160 kilometers of natural stream channel no longer carry regular flows and the river doesn’t reach the sea. Because of this, the first binational environmental water allocation between Mexico and the United States was initiated (termed Minute 319) and two environmental flows were agreed upon.Those separate flow events provided an opportunity to investigate streambed infiltration under very different hydrographs, a “base flow” and a “pulse flow”. In this work, we evaluate the infiltration process using heat as a tracer and compare these point measurements to a saturated/unsaturated 2-D numerical model of a cross-section of the river. Heat tracer analysis showed that in both events, infiltration was high at the start and then decreased over time, from a maximum of 0.60md−1 during the pulse flow and 1.60md−1 during base flow. Monte Carlo analyses for the pair of temperature sensors at each event showed that uncertainty is greater at higher vertical fluxes; therefore greater during base flow (0.4md−1) and lower at pulse flow (0.2md−1). The total volume infiltrated during 6 and 8days of the pulse and base flows (March 25–30 and September 7–14, respectively) was 151,714m3 and 307,610m3, respectively. In contrast, the 2-D numerical model showed 241,780m3 and 125,295m3 across the cross-section in a 500m longitudinal distance of the river channel, during the pulse flow and base flow, respectively. In both models, the flux was highest during the initial days of each event. These results suggest that for future environmental flows focused on longitudinally reconnecting the river in conditions similar to those presented in this study, the minimization of channel transmission losses could be achieved through lower, consistent flows. However, this would not lead to reconnection of surface water and groundwater and therefore propagation of the wetting front laterally, which benefits restoration areas.

RADIOLARIAN AGE AND LITHOSTRATIGRAPHY OF LATE CRETACEOUS PELAGIC SEDIMENTS OVERLYING BASALTIC EXTRUSIVE ROCKS, NORTHERN OMAN MOUNTAINS

A detailed radiolarian biostratigraphy of pelagic sediments overlying basaltic extrusive lavas of the Oman Ophiolite is reported for the type locality of the Suhaylah Formation near the Wadi Jizzi River, northern Oman Mountains. The extrusive lavas in the studied section are classified as V1 lava produced by mid-ocean-ridge magmatism. The sedimentary succession in the type section (ca. 18 m thick) is subdivided into three units (in stratigraphic order): metalliferous sediments (Unit 1), red mudstone intercalated with radiolarian chert (Unit 2), and micritic limestone (Unit 3). The recovery of well-preserved radiolarians from all units led to the recognition of three distinctive assemblages: Assemblage A, obtained from metalliferous sediments and chert intercalations within red mudstone, could be correlated with the middle-late Cenomanian fauna; Assemblage B, recovered from red mudstone and chert, is assigned to the early Turonian, based on correlation with radiolarian occurrences across the Cenomanian-Turonian boundary; Assemblage C, recognized in micritic limestone, is broadly identified as Turonian-Coniacian. The age of the Suhaylah Formation has previously been interpreted as early Cenomanian to Coniacian-Santonian; however, the revised age could be from late Cenomanian to Turonian-Coniacian. The estimated possible maximum age of metalliferous sediments (96.5-93.9 Ma) is in good agreement with high-precision U-Pb zircon dates of ophiolite crust attributed to ridge magmatism. The depositional age of the pelagic sediments clearly indicates that the ridge magmatism had ended by ca. 95.5 Ma.

L'Italia e il primo conflitto globale, 1914-1918

L'Italia e il primo conflitto globale, 1914-1918