Ephemeral Research Articles

Decreasing Downstream Channel Capacity of a Low-Lying Ephemeral River of Bengal Basin, Eastern India

This paper discusses various aspects of channel morphology on an ephemeral Dwarkeswar River from the western part of the Bengal Basin. Geologically, it extends from the Proterozoic Granite Gneiss Complex to recent Holocene alluvium, creating three typical geomorphic regions, e.g. dissected plateau, plateau-fringe and alluvial plain. Sixty cross sections from the source to the mouth of the river were surveyed, and the bankfull channel parameters were measured. Consequently, sediment samples were collected and Manning’s roughness coefficient were determined to estimate velocity, discharge and stream power. The exponents of hydraulic geometry (width, depth and velocity) vary significantly with respect to physiographic divisions of the study area. Width, width–depth ratio and channel capacity enlarge up to the plateau-fringe area. Thereafter, reduction of channel capacity, width and W/D ratio has been observed in the alluvial plain area by 81.3%, 87.3% and 91.3%, respectively, which is associated with lowering of sea level, high topographic sinuosity index, extremely elongated basin, very low slope, wide flood plain area and cohesive bank materials. So, channel capacity reduces in the downstream direction and floods became an unavoidable part of this region.

How Do Gaining and Losing Streams React to the Combined Effects of Climate Change and Pumping in the Gharehsoo River Basin, Iran?

AbstractProjections of potential impacts of climate change and groundwater abstraction on gaining and losing streams, particularly in ephemeral river basins exhibiting sporadic and intricate flux exchanges, have remained largely unexplored. To fill this gap, we propose a promising modeling scheme based on the new fully integrated hydrological model SWAT‐MODFLOW‐NWT, calibrated and validated for 1978–2012, to quantify the intertwined surface‐groundwater interactions under a conjuncture of three climatic emission scenarios (RCP 2.6, 4.5 and 8.5) and two groundwater pumping variants: “pumping” (extending current groundwater utilization into the future) and “nonpumping” (assuming a complete cease of pumping in the future). By forcing the integrated model with future downscaled climate predictors of CanESM2 under the aforementioned RCPs for three time slices up to year 2100, projections of various water resources components for the Gharehsoo River Basin (GRB), in northwestern Iran were made. Results demonstrate that because of a general decrease of future precipitation, though with ups and downs across the total projection period, most of the surface and ‐subsurface budget quantities and fluxes are substantially affected. In particular, future groundwater discharge (baseflow) to the gaining streams will be more influenced by the “pumping” variant (increasing and decreasing for “nonpumping” and “pumping”, respectively) than the concentrated groundwater recharge from the losing streams (decreasing and increasing for “nonpumping” and “pumping”, respectively). Future water yield and groundwater storage will also diminish and, surprisingly, this cannot be alleviated by future “nonpumping”, indicating the groundwater overutilization is the compelling reason for the future water scarcity in the GRB, rather than climate change alone.

Abandoned Mine Tailings Affecting Riverbed Sediments in the Cartagena–La Union District, Mediterranean Coastal Area (Spain)

This study presents the results of the geoenvironmental characterization of La Matildes riverbed, affected by mine tailings in the Cartagena–La Unión district, Murcia (southeast Spain). Soils and riverbeds in this area are highly polluted. Two Electrical Resistivity Imaging (ERI) profiles were carried out to obtain information about the thickness of the deposits and their internal structure. For the mine tailings deposits of La Murla, a tributary of the El Miedo riverbed, the geophysical method imaged two different units: the upper one characterized by low resistivity values and 5–8 m thickness, correlated with the mine tailings deposits; and the lower more resistive unit corresponding to the Paleozoic metasediments bedrock. The ERI profile transverse to the Las Matildes dry riverbed revealed the existence of three different units. The uppermost one has the lowest resistivity values and corresponds to the tailings deposits discharged to the riverbeds. An intermediate unit, with intermediate resistivity values, corresponds to the riverbed sediments before the mining operations. The lower unit is more resistive and corresponds to the bedrock. Significant amounts of pyrite, sphalerite, and galena were found both in tailings and riverbed sediments. The geochemical composition of borehole samples from the riverbed materials shows significantly high contents of As, Cd, Cu, Fe, Pb, and Zn being released to the environment. Mining works have modified the natural landscape near La Unión town. Surface extraction in three open-pit mines have changed the summits of Sierra de Cartagena–La Unión. Rock and metallurgical wastes have altered the drainage pattern and buried the headwaters of ephemeral channels. The environmental hazards require remediation to minimize the environmental impact on the Mar Menor coastal lagoon, one of the most touristic areas in SE Spain.

Lateral and longitudinal distribution of riparian vegetation along an ephemeral river in Namibia using remote sensing techniques

Ephemeral rivers are key features of desert ecosystems, providing shallow groundwater and occasional surface flow, but compared to perennial systems, the structure of riparian forests in ephemeral rivers and their interactions with the hydrologic regime are poorly understood. This study examines the distribution of riparian woody species in the ephemeral Kuiseb River in central Namibia. Unmanned aerial vehicle (UAV) and satellite imagery were used to examine the structure of the riparian forest across lateral and longitudinal gradients. Woody plant abundance peaked in the terminal alluvial zone, the reach of the river where floods typically run dry. The five dominant species exhibited similar spatial patterns at latitudinal and longitudinal scales. Faidherbia albida and Salvadora persica were found more proximal to the active channel and concentrated in the terminal alluvial zone. Acacia (Vachellia) erioloba, Euclea pseudebenus, and Tamarix usneoides were more evenly dispersed laterally across the riparian zone and along the river's longitudinal profile. These spatial patterns correspond to plant physiological properties of hydrological dependence and gradients of water availability and soil composition. The tight coupling of plant distributions with water availability highlights the need for long-term monitoring of ephemeral riparian vegetation in light of potential future changes to the global hydrologic regime.

Vegetation dynamics of ephemeral and perennial streams in mountainous headwater catchments

Ephemeral and perennial streams of mountainous catchments in Sabaragamuwa Province of Sri Lanka and Hong Kong of China were studied for two years on vegetation dynamics. Each year, sampling was conducted during a period when ephemeral streams had low surface flows. Sampling was realized contiguously using belt transects. The standing crop biomass (hereafter biomass) of herbaceous vegetation in ephemeral channels was comparatively lower than perennials and so was the herb diversity. Herb diversity showed a peak from 1.5 to 4.5 m from the centerline/thalweg of ephemeral and perennial streams. Out of 24 herbs, only three were common for both. A peak herb biomass zone was observed in perennials in the same region where diversity peaked. In ephemerals, herb biomass increased laterally up to ∼1.5 m, and was constant thereafter. Seedling experiment results tallied with the field diversity observations of both stream types, and suggested that seed dispersion was the main reason for herb colonization. Furthermore, it showed sapling emergence to be significantly higher in perennials than ephemerals. Return period of annual maximum monthly rainfall was a strong indicator of age of trees in ephemeral streams, and elucidated the possibility of hindcasting past flow episodes. Electrical conductivity was significantly high in ephemeral streams among all the water quality parameters. The contents of the water nutrients were approximately the same in both stream types. While recommending further studies on eco-hydrology of ephemerals, we recognize ephemeral streams to be valuable references in climate change studies due to their responsiveness and representativeness in long term hydrological changes.

Mapping Paleohydrology of the Ephemeral Kuiseb River, Namibia, from Radar Remote Sensing

The Kuiseb River is one of the major ephemeral rivers of Western Namibia, setting the northern limit of the Namib Sand Sea and outflowing in the Atlantic Ocean at Walvis Bay. Such ephemeral rivers are of the highest importance for the country since they are related both to recent past climatic conditions and to potential water resources. Using high-resolution radar images from the Japanese ALOS-2 satellite, we mapped for the first time the numerous channels hidden under the surface aeolian sediments: while the non-permanent tributaries of the Kuiseb River appear north of its present-day bed, a wide paleochannel system running westward, assumed by previous studies, could be clearly observed in the interdune valleys in the south. Radar-detected channels were studied during fieldwork in May 2019, which produced both subsurface ground-penetrating radar profiles and high-resolution drone-generated digital elevation models. It allowed us to confirm the existence of the “Paleo–Kuiseb” drainage system, a remnant of the Holocene history of the Kuiseb River, moving northward under the progression of the Namib Sand Sea. Our observations also contribute to the explanation of the young age of the linear dunes at the northern edge of the Namib Sand Sea, which are currently active and are pushing the Kuiseb River course toward the north.

Performance of an Unmanned Aerial Vehicle (UAV) in Calculating the Flood Peak Discharge of Ephemeral Rivers Combined with the Incipient Motion of Moving Stones in Arid Ungauged Regions

Ephemeral rivers are vital to ecosystem balance and human activities as essential surface runoff, while convenient and effective ways of calculating the peak discharge of ephemeral rivers are scarce, especially in ungauged areas. In this study, a new method was proposed using an unmanned aerial vehicle (UAV) combined with the incipient motion of stones to calculate the peak discharge of ephemeral rivers in northwestern China, a typical arid ungauged region. Two field surveys were conducted in dry seasons of 2017 and 2018. Both the logarithmic and the exponential velocity distribution methods were examined when estimating critical initial velocities of moving stones. Results reveal that centimeter-level orthoimages derived from UAV data can demonstrate the movement of stones in the ephemeral river channel throughout one year. Validations with peak discharge through downstream culverts confirmed the effectiveness of the method. The exponential velocity distribution method performs better than the logarithmic method regardless of the amount of water through the two channels. The proposed method performs best in the combination of the exponential method and the river channel with evident flooding (>20 m3/s), with the relative accuracy within 10%. In contrast, in the river channel with a little flow (around 1 m3/s), the accuracies are weak because of the limited number of small moving stones found due to the current resolution of UAV data. The poor performance in the river channel with a little flow could further be improved by identifying smaller moving stones, especially using UAV data with better spatial resolution. The presented method is easy and flexible to apply with appropriate accuracy. It also has great potential for extensive applications in obtaining runoff information of ephemeral rivers in ungauged regions, especially with the quick advance of UAV technology.

Adaptive significance of the transparent body in the tadpoles of ornamented pygmy frog, Microhyla ornata (Anura, Amphibia)

In Southern India, during the Southwest monsoon phase, the newly formed ephemeral water bodies harbour several species of tadpoles as well as some of their predators. Tadpoles of Microhyla ornata dwell in surface or column zones of water. They face predation threat from aquatic insect predators and carnivorous tadpoles of other anurans though they are invisible due to their transparent body form. We tested whether transparent body form of M. ornata tadpoles is a useful attribute against predation by exposing tail fin stained (with the Nile blue) subjects to a naturally occurring predator (Hoplobatrachus tigerinus tadpoles that detect prey using both visual and chemical cues). The study shows that susceptibility of stained M. ornata tadpoles to predation increased significantly compared to the unstained transparent individuals. We conclude that the transparent body form is of great significance in escaping predation during the larval phase of life in M. ornata.

Droughts in the desert: Medieval Warm Period associated with coarse sediment layers in the Gulf of Aqaba‐Eilat, Red Sea

AbstractProlonged droughts can cause environmental stress, even in ecosystems that are already adapted to dry conditions. In these areas life greatly depends on rare, sporadic rainfall events that can produce flash floods. Today, urban expansion, population growth and development are occurring worldwide, including along hyperarid coastlines, an ecological zone on the extreme of habitability. In such places, the absence of the already limited precipitation can lead to long‐lasting damage, and recognizing drought conditions in the past is useful for planning. Recognizing droughts, however, is challenging because they are not known as depositional events, and therefore may be under‐recognized in the sedimentological record. Floods in these hyperarid deserts carry eroded sediments and deposit them in either terrestrial or marine terminal basins. In the hyperarid (ca 30 mm rain per year) desert surrounding the northern Gulf of Aqaba‐Eilat some flash floods reach the sea and deposit alluvial sediments (mostly silt and clay) on the shelf. Following a recent 17 year drought period (1995 to 2012) a coarser surface layer was recognized offshore the outlet of an ephemeral river, despite the lack of incoming flood material. This coarsened layer resulted from a prolonged period wherein mixing and winnowing of fine particles at the surface was not interrupted by recurrent flash floods. In the bottom of two sediment cores collected from the same shelf, a similarly coarsened layer was observed. The terminal level of this deep coarse layer was dated to ca 660 yr bp, corresponding with the end of the Medieval Warm Period (ca 1350 ad). These findings suggest that the medieval anomaly resulted in a prolonged drought period in this already arid region. These results present a new interpretation of grain‐size distribution records that provides a means to reconstruct drought histories in hyperarid regions globally.

Sediment consolidation in ephemeral river: the effect of applied loading on soil properties and dredging method selection

ABSTRACT Bengawan Solo River, a typical large ephemeral river in Indonesia, is facing stream problems induced by the erosion and deposition of sediment. Imbalance between these two phenomena on the riverbed can lead to excessive sedimentation, increased risk of flooding, and formation of sandbars. One proposed solution to address this problem is dredging. However, this process can have potential negative effects on the environment, such as removal or destruction of the biota in the dredged materials, increased turbidity, as well as coverage of the benthos in the vicinity. Also, different dredging methods are needed to suit sediments with different properties. Therefore, the knowledge of the deposited sediment properties is required so that appropriate methods can be selected. The sediment characteristics were obtained by performing laboratory tests on physical and consolidation properties and shear strength tests of a soil sample. The results indicate that the materials were broadly grouped into sandy sediment in downstream areas and clayey sediment in estuary areas. The distribution of sediment properties varies with depth because of subsequent erosion and deposition over time. Additionally, the distribution also shows that sand content decreases as the origin of sample approaches estuary areas. Erosion is predominant at locations with small hydraulic radius and high flow velocity, mostly at downstream areas, whereas deposition is predominant at locations with a large hydraulic radius and low flow velocity, specifically at estuary areas. The shear strength increases as the loads imposed by the self-weight of sediment layer increase. The analysis suggests that sediments cannot be eroded naturally as they have a shear strength that exceeds the small-capacity dredging method (); therefore, the removal of excess sediment in such areas requires dredging methods of larger capacities (such as grab dredger).

Modelling the water level of the alluvial aquifer of an ephemeral river in south-western Zimbabwe

ABSTRACT Water from the alluvium of ephemeral rivers in Zimbabwe is increasingly being used. These alluvial aquifers are recharged annually from infiltrating floodwater. Nonetheless, the size of this water resource is not without limit and an understanding of the hydrological processes of an alluvial aquifer is required for its sustainable management. This paper presents the development of a water balance model, which estimates the water level in an alluvial aquifer recharged by surface flow and rainfall, while allowing for abstraction, evaporation and other losses. The model is coupled with a watershed model, which generates inflows from upland catchment areas and tributaries. Climate, hydrological, land cover and geomorphological data were collected as inputs to both models as well as observed flow and water levels for model calibration and validation. The sand river model was found to be good at simulating the observed water level and was most sensitive to porosity and seepage.

Dimensionless morphological ratios versus stream power variations at bankfull stage in an ephemeral channel

Dimensionless morphological ratios (DMR) generally are used in systemic proposals for stream classification and river restoration projects. Often, such morphometric parameters, including field data from channel cross sections, develop into a template for a given geomorphic reference site. In this study, high-resolution Digital Terrain Models (HRDTMs), combined with orthophotographs from 2018 and ground-based surveys, were used to analyze the spatial variability of DMR in a semi-arid ephemeral stream subject to changes in stream power under bankfull conditions. In particular, a channel reach of 2.7 km in length along the Upper Mula stream in southeastern Spain was chosen to test the relationships between the two types of variables. Rosgen's DMR (width to depth ratio, entrenchment ratio, bank height ratio) and hydraulic data at bankfull stage (flow velocity, Froude number, shear stress, mean stream power and energy gradient, among others) were calculated by 1D hydrodynamic modeling and HRDTMs prior entry of field information. The resulting maps allowed comparison of stream power with DMR in relation to the channel stretch class and bed stability. The results showed similar spatial patterns for the width to depth ratio and the bank height ratio. The average values estimated in bend stretches were lower than along straight and slightly sinuous stretches and very similar to those of sub-reaches from the inflection point to the meander bend apex. However, the entrenchment ratio followed a different pattern, according to which the straight and slightly sinuous stretches were the most entrenched and the bend stretches presented a more moderate average entrenchment ratio. In addition, the energy balance and power gradient also experienced spatial variations in relation to the bed stability and DMR. Only in highly incised sub-reaches were such relationships not significant. The lack of a significant correlation between excess energy and bank height ratio or width to depth ratio over short lag distances was also verified, regardless of the affected bedforms. An ANOVA showed important differences between the straight and slightly sinuous stretches and bend stretches, which were strongly influenced by the incision and entrenchment ratios and the maximum bankfull depth.

Use of optical and radar remote sensing satellites for identifying and monitoring active/inactive landforms in the driest desert in Saudi Arabia

Observing Earth from the space is key for monitoring land-surface dynamics and probing near-surface geomorphic and geological features, including those obscured by sand sheets/dunes and human activity. The hyper-arid area of the Arabian Peninsula was selected for detecting and extracting obscure paleohydrological systems and modeling the spatio-temporal dynamics of sand dunes using synthetic aperture radar (SAR) and optical high-resolution remote sensing images. Interferometric synthetic aperture radar (InSAR) coherence change detection (CCD) using Sentinel-1 imagery was performed, revealing subtle changes in the surficial landforms of the study area. These images also discriminated between active and inactive geomorphic features. In addition, low-frequency L-band Advanced Land Observing Satellite/Phased Array type L-band Synthetic Aperture Radar (ALOS/PALSAR) and Shuttle Radar Topography Mission (SRTM) data revealed the details of paleochannels in the basins that drain into the Arabian Gulf. These ephemeral rivers are the source of sand that was later reshaped into dunes by aeolian processes. The results also revealed that the morphology and extension of dunes were clearly influenced by topography, slope, and wind velocity and direction, rather than human activities. Knowledge gained by exploring desert features is essential for planning settlements and development, and integrated approaches using a variety of remote sensing datasets are key for enhancing Earth observation across a range of spatial and temporal scales.

Sediment budget of high mountain stream channels in an arid zone (High Atlas mountains, Morocco)

In an arid zone the sediment budget is predominantly dependent on runoff, which is controlled mainly by the type of rainfall. Sediment budget calculation is one of the indirect methods of estimating channel morphodynamics. This method is advised here since it is not possible to directly measure this important hydrological indicator of environmental dynamics. This is because in small mountain catchments of an arid zone it is impossible to obtain flow rates due to factors such as the amount and size of transported rock debris, as well as the episodic and sudden nature of precipitation events. The research was conducted in 3 catchments (2.95 km2, 7.39 km2, 22.73 km2) situated within the boundaries of the basin of the upper Dades, on the southern slopes of the High Atlas in Morocco. The rivers of these catchments, tributaries to a trunk river Dades, are ephemeral and mostly bedrock depending on lithology of the geology. Three automatic weather stations were installed there. Precipitation events ≥ 10 mm (51 rains in 3 catchments) were used in the analysis. Simple rainfall typology (3 types) was devised for these events. During the research period seasonally repeated (6 times) measurements of topography were obtained from 21 cross-section profiles of streams of different order. These measurements formed a basis for calculating both the intensity of flow in ephemeral rivers (max 69,6 m/s) and the sediment budget. In 70% of analysed channel cross-sections erosion was dominant. The average change of the surface area of the cross-section profile is −82%. The maximum seasonal (between measurements) enlargement of the surface cross-section (erosion) is as high as 128%. The lower catchment, which is predominantly composed of conglomerates, distinctly shows the slightest changes of the cross-section profile surfaces, max 24%. The average volume of channel material displaced at the measurement point is 1.07 m3 (max 9.81 m3). There is evidence that not only high intensity rains, but also less intense but longer lasting rains, amounting to high precipitation totals (type C), may result in the highest channel sediment budgets. Differences between a catchment lithology composed of limestones and marlstones and that composed of conglomerates have only a minor impact on sediment budgets in the first and second order channels, whereas in the channels of the third and fourth order this impact is much higher. It was found that sediment budgets calculated for individual channels were higher for the catchments composed of limestones and marlstones, than for those composed of conglomerates, even though the catchments of different lithology may have had the same number of tributaries. This suggests that the sediment supply from slopes is comparatively larger in the catchments dominated by limestones and marlstones.

Channel mobility drives a diverse stratigraphic architecture in the dryland Mojave River (California, USA)

AbstractThe links between flood frequency and rates of channel migration are poorly defined in the ephemeral rivers typical of arid regions. Exploring these links in desert fluvial landscapes would augment our understanding of watershed biogeochemistry and river morphogenesis on early Earth (i.e. prior to the greening of landmasses). Accordingly, we analyse the Mojave River (California), one of the largest watercourses in the Great Basin of the western United States. We integrate discharge records with channel‐migration rates derived from dynamic time‐warping analysis and chronologically calibrated subsidence rates, thereby constraining the river's formative conditions. Our results reveal a slight downstream decrease in bankfull discharge on the Mojave River, rather than the downstream increase typically exhibited by perennial streams. Yet, the number of days per year during which the channel experiences bankfull or higher stages is roughly maintained along the river's length. Analysis of historical peak flood records suggests that the incidence of channel‐formative events responds to modulation in watershed runoff due to the precipitation in the river's headwaters over decades to centuries. Our integrated analysis finally suggests that, while maintaining hydraulic geometries that are fully comparable with many other rivers worldwide, ephemeral desert rivers akin to the Mojave are capable of generating a surprisingly wide range of depositional geometries in the stratigraphic record. © 2020 John Wiley & Sons, Ltd.

Numerical Approaches for Estimating Daily River Leakage from Arid Ephemeral Streams

Despite the significance of river leakage to riparian ecosystems in arid/semi-arid regions, a true understanding and the accurate quantification of the leakage processes of ephemeral rivers in these regions remain elusive. In this study, the patterns of river infiltration and the associated controlling factors in an approximately 150-km section of the Donghe River (lower Heihe River, China) were revealed using a combination of field investigations and modelling techniques. The results showed that from 21 April 2010 to 7 September 2012, river water leakage accounted for 33% of the total river runoff in the simulated segments. A sensitivity analysis showed that the simulated infiltration rates were most sensitive to the aquifer hydraulic conductivity and the maximum evapotranspiration (ET) rate. However, the river leakage rate, i.e., the ratio of the leakage volume to the total runoff volume, of a single runoff event relies heavily on the total runoff volume and river flow rate. In addition to the hydraulic parameters of riverbeds, the characteristics of ET parameters are equally important for quantifying the flux exchange between arid ephemeral streams and underlying aquifers. Coupled surface/groundwater models, which aim to estimate river leakage, should consider riparian zones because these areas play a dominant role in the formation of leakage from the river for recharging via ET. The results of this paper can be used as a reference for water resource planning and management in regulated river basins to help maintain riparian ecosystems in arid regions.

Characterization of recharge processes and groundwater flow paths using isotopes in the arid Santanghu basin, Northwest China

Isotopes and hydrochemistry were used to characterize the recharge and flow of groundwater in the arid Santanghu basin in Northwest China. The results of isotopic measurement and hydrochemical facies indicate that the predominant recharge mechanism is via rivers and streams. Modern recharge only occurs in the piedmont area of Moqinwula Mountains by ephemeral rivers, and the main recharge source is precipitation in the mountain areas at an elevation of about 2,200 m above sea level. Two recharge mechanisms were identified by stable isotope methods: the ephemeral stream recharge in the piedmont with the occurrence of evaporation during recharge, and subsurface inflow recharge from the mountain regions. Diffuse recharge derived from precipitation in the basin can be ignored because of the scarcity of precipitation and intense evaporation. Groundwater in the Paleogene and Neogene confined aquifers could represent recharge during cooler climatic conditions, rather than latitude or altitude effects, signified by tritium-free samples and significant depletion of heavy stable isotopes throughout the study area. Groundwater age data suggest that central faults are controlling the flow paths of the regional groundwater flow system. Groundwater moves from the piedmont plain to the basin lowland area through lateral flow, and changes flow direction to the spring zone of Hanshuiquan Oasis because of the barrier of the central faults. A conceptual model was defined, for better understanding of the groundwater recharge and flow systems. The major findings of this study have significant implications for groundwater protection and management in arid basins.

Phenomena of the ephemeral. Other ephemeral architecture in Colombia

espanolEste articulo tiene como objetivo analizar el fenomeno de la arquitectura efimera en Colombia, desde un angulo donde lo efimero se deriva de las condiciones de durabilidad de las obras como resultado de factores de calidad y/o del abandono de estas arquitecturas. Por lo tanto, la investigacion tuvo como punto de partida metodo-logico una revision historiografica contrastada, que incluyo visitas a arquitecturas en las que se ha visto comprome-tida su estabilidad y por ende su durabilidad, como factor que ha determinado su condicion efimera, toda vez que se trata de arquitecturas que han desaparecido de manera subita, o que una vez abandonadas, se encuentran en un lento proceso de desaparicion. El analisis de estas arquitecturas permitio detectar dos fenomenos principales de lo efimero en Colombia, tomando como punto de partida la velocidad y la intencionalidad en la desaparicion de estas arquitecturas, (Utopias efimeras: lugares ideales para el habitat, involuntariamente efimeros) y (Distopias efimeras: lugares imposibles para el habitat, deliberadamente efimeros) Estas dos categorias de aproximacion delimitan un panorama alternativo de la arquitectura efimera en Colombia, que redimensiona y amplia la vision tradicional de este tipo de arquitectura. EnglishThe main purpose of this paper is analyzing the phenomenon of ephemeral architecture in Colombia from an angle where the ephemeral is derived from the durability of the works, as a result of quality factors and/or the abandonment of these architectures. Therefore, the methodological starting point of the research was a contrasted historiographic review, including visits to architectures whose stability and, hence, durability, have been questioned as a factor that has determined their ephemeral condition, since these architectures have disappeared suddenly or, once abandoned, are in slowly disappearing. The analysis of these architectures allowed detecting two main ephemeral phe-nomena in Colombia, taking as a starting point the speed and the intentionality in the disappearance of these architec-tures, (Ephemeral utopias: ideal places for habitat, unintentionally ephemeral) and (Ephemeral dystopias: impossible places for habitat, deliberately ephemeral). These two categories of approximation define an alternative panorama of ephemeral architecture in Colombia, which resizes and expands the traditional view of this type of architecture. portuguesEste artigo tem como objetivo principal, analisar o fenomeno da arquitetura efemera na Colombia a partir De um ângulo onde o efemero deriva das condicoes de durabilidade das obras como resultado de fatores de qualidade e/ou do abandono destas arquiteturas. Por conseguinte, a pesquisa teve como ponto de partida metodolo-gico uma revisao historiografica comprovada, que incluiu visitas a arquiteturas em que a sua estabilidade e, portanto, a sua durabilidade foram comprometidas como factor que determinou a sua condicao efemera, ja que sao arquite-turas que desapareceram de repente, ou uma vez abandonadas, estao num lento processo de desaparecimento. A analise destas arquiteturas nos permitiu detectar dois fenomenos principais do efemero na Colombia, tomando como ponto de partida a velocidade e intencionalidade no desaparecimento destas arquiteturas, (Utopias efemeras: luga-res ideais para o habitat, nao intencionalmente efemeras) y (Distopias efemeras: lugares impossiveis para o habitat, deliberadamente efemeras). Estas duas categorias de abordagem delimitam um panorama alternativo de arquitectura efemera na Colombia, que redimensiona e expande a visao tradicional deste tipo de arquitectura.

Ephemeral cultural landscape. The vernacular Mayan heritage in its relationship with the territory

espanolPara los mayas la subjetivacion de las cosas es esencial en su filosofia de habitar el territorio, en donde todos son sujetos; por lo tanto, su arquitectura vernacula tambien asume esta percepcion al cobrar vida la casa. Para llegar a este precepto, se desarrollo un proyecto de investigacion que busco entender los procesos de transmision de los saberes para amarrar (construir) su arquitectura vernacula, en un estudio que involucro metodologias tanto del area de la arquitectura como de la antropologia. Durante el levantamiento de datos arquitectonicos se percato de este proceso de vida de las casas de los mayas, las cuales, al ser de materiales perecederos en su mayoria, llegan a un tiempo de vida, pero a la par se estan amarrando nuevas casas que cobraran vida cuando sean habitadas por las nuevas familias. Lo anterior hace de la arquitectura vernacula de los mayas efimera. Estos saberes constructivos tambien se han utilizado para crear otra arqui-tectura mucho mas efimera: los tablados (coso taurino) para las corridas de toros; al estar estos tablados vinculados con la fiesta patronal, su existencia es de solo una semana, conformando un paisaje cultural efimero propio de las poblaciones mayas de la Peninsula de Yucatan. Esta cualidad de lo efimero hace de la arquitectura vernacula maya una caracteristica esencial, pero tambien son parte vital de su existir al ser los escenarios de aprendizaje de los saberes constructivos. portuguesPara os maias a subjetivacao das coisas e essencial em sua filosofia de habitar o territorio onde todos estao sujeitos; portanto, sua arquitetura vernacular tambem assume essa percepcao, dando vida a casa. Para atingir esse preceito, foi desenvolvido um projeto de pesquisa que buscava entender os processos de transmissao de conhecimento para amarrar (construir) sua arquitetura vernacular, em um estudo que envolveu metodologias tanto da area de arquitetura quanto da antropologia. Durante a pesquisa de dados arquitetonicos, percebeu-se esse processo de vida das casas maias que, sendo principalmente materiais pereciveis, atingem um tempo de uso mas, ao mesmo tempo, novas casas que ganharao vida ao serem habitadas por novas familias. O exposto acima torna a arquitetura vernacular dos maias efemera. Esses conhecimentos construtivos tambem foram usados para criar outra arquitetura muito mais efemera: tablados para touradas, ligados aos santos padroeiros, sua existencia e de apenas uma semana, formando uma paisagem cultural efemera, tipica das populacoes maias da peninsula de Yucatan. Essa qualidade do efemero torna a arquitetura vernacular maia uma caracteristica essencial, mas elas tambem sao uma parte vital de sua existencia, pois sao os cenarios de aprendizagem do conhecimento construtivo. EnglishFor the Mayans, the subjectivation of things is essential in their philosophy of inhabiting the territory, where they are all subjects; therefore, their vernacular architecture also assumes this perception on bringing the house to life. To arrive at this precept, a research project was developed that sought to understand the processes of transferring knowledge to tie (build) their vernacular architecture, in a study that involved methodologies of both the area of architecture and anthro-pology. While surveying architectural data, this process of life of the Mayan houses was noticed, which, on mainly being made from short-lasting materials, have a given lifespan but, at the same time, new houses are being tied, that will come alive when they are inhabited by new families. This makes the vernacular architecture of the Mayans ephemeral. The knowledge to tie-up has also been used to create another much more ephemeral architecture: The “tablados” (bullrings) for bullfights. On these “tablados” being linked to the patron saint, they only exist for one week, forming an ephemeral cultural landscape typical of the Mayan populations of the Yucatan Peninsula. This ephemeral quality is an essential characteristic of the Mayan vernacular architecture, but they are also a vital part of their existence on being the scenarios to learn about construction.

Installed art in the construction of learning spaces. Notes on ephemeral projects in the University of Talca’s School of Architecture.

espanolEl presente escrito indaga sobre los procesos y metodos del arte instalado como una propuesta artistica que explora la espacialidad, la participacion, un caracter intermedial y se define como efimero. Todas las caracteristicas anteriores lo connotan como un espacio constructor de conocimiento y desde alli como aporte a la creacion de espacios de aprendizaje activos. Hay en esta practica, desde sus procesos y desarrollos estructurales, un aporte a la ensenanza, en tanto su caracter procesual, transformador y creativo. De tal forma, para acometer metodologicamente esta discusion, se pondran en relacion los conceptos y practicas que aborda el arte instalado y sus formas de produccion de conocimiento; las implicancias academicas y sociales que puedan aportar y la practica de algunas obras efimeras desarrolladas en la Universidad de Talca, donde, en conjunto, se propone que dichos procesos parecen favorecer la adquisicion de habilidades fundamentales como la reflexion, el accionar critico, la participacion, la cooperacion y la sensibilidad. EnglishThis paper, looks into the processes and methods of installed art as an artistic proposal that ex-plores its spatiality, participation, an inter-medial nature and which is defined as ephemeral. All these aforemen-tioned characteristics connote it is a space for building knowledge and, from there, a contribution towards the creation of active spaces for learning. There is, in this practice, from its structural processes and developments, a contribution to education, in terms of its procedural, transforming and creative nature.In this way, to undertake this discussion methodologically, the concepts and practices that address installed art and its forms of knowledge production; the academic and social implications that these can contribute and the practice of some ephemeral works carried out at the University of Talca will be connected, where together, it is suggested that these processes seem to favor the acquisition of fundamental aptitudes like: reflection, critical action, participation, cooperation and sensitivity. portuguesEste artigo investiga os processos e metodos da arte instalada como uma proposta artistica que explora espacialidade, participacao, natureza intermediaria e e definida como efemera. Todas as caracteristicas anteriores o conectam como um espaco de construcao de conhecimento e, a partir dai, como uma contribuicao para a criacao de espacos de aprendizado ativos. Existe nessa pratica, a partir de seus processos e desenvolvi-mentos estruturais, uma contribuicao ao ensino, como seu carater processual, transformador e criativo.Assim, para empreender metodologicamente essa discussao, serao relacionados os conceitos e praticas que se relacionam as artes e suas formas de producao de conhecimento; as implicacoes academicas e sociais que eles podem contribuir e a pratica de alguns trabalhos efemeros desenvolvidos na Universidade de Talca, onde, juntos, propoe-se que esses processos parecam favorecer a aquisicao de habilidades fundamentais como reflexao, acao critica, participacao, Cooperacao e sensibilidade.