Torrential River Research Articles

Los diques de corrección hidrológica como instrumentos de cuantificación de la erosión

Check dams have as a main purpose to retain sediments and reduce the peak flows in torrential rivers and ravines. The sediments retained upstream of the dams constitute a very valuable information source to quantify soil erosion and transport at basin scale. The aim of this work is to use the accumulated sediments in 425 check dams constructed in the Quipar River (a tributary of the Segura River, SE Spain, with an area of 826 km2). From all the check dams constructed in two periods (1962 and 1996), in 378 it was possible to quantify the volume of retained sediments, amounting to a total of 687.416 tons. Besides, erosion rates were estimated in 195 check dams. Erosion rates show a high variability. Average erosion for the whole basin of the Quipar River is about 4 t ha-1 yr -1, a value similar to that obtained by bathimetric techniques, although much lower than that calculated with USLE. Lithology is the most determinant factor in explaining the erosion rate, in such a manner that check dams withy the highest erosion rates are located on marls, conversely to those on limestones.

Coladas de piedras (debris flows) y dinámica fluvial en ríos torrenciales del Pirineo Central : el caso del río Ijuez

Debris flows and fluvial dynamics in torrential rivers of Central Pyrenees. A great accumulation o heterometric deposits is studied in the headwater of the Ijuez river, Central Spanish Pyrenees, triggered by successive debris flows. The granulometric and sedimentological characteristics of the depositare analyzed and they are compared with the fluvial-type sedúnents, located downstream. Some aspects of the influence of these deposits on the general dynamics of the main river are discussed.

Ecologically Sustainable Water Management:Role Of The Academy To Face The Development?Pressures And Challenges – Experiences In Chile

The experience of the earthquake and tsunami of February 27, 2010 revealed a variety of shortcomings in ensuring the safety of the population, urban centers, coastal areas and land-use situations, which resulted in the loss of many lives and extensive damage to urban infrastructure and economic productivity, with signifi cant social impact. Because of its complex geography and the permanent risk of natural disasters (earthquakes, tsunamis, volcanic eruptions, and torrential river fl oods), as well vulnerability to climate change, Chile represents important academic challenges to defi ne research programs to provide preventive and mitigating actions to address this reality. It must be added that interventions with large-scale projects (hydropower, irrigation channels, civil works in areas with river fl ooding and along the coastline) as well as the intensive exploitation of natural resources (water, soil and vegetation) combine to form a complex environmental situations that is diffi cult to understand and manage. In response to this situation, the University of Concepcion through its Research Offi ce created the Reconstruction Program, composed of working groups in various fi elds to analyze the consequences of the seismic event and tsunami and develop proposals to address the reconstruction measures for the region, as well as to develop new approaches and tools to face this reality. From the academic point of view, this represents opportunities for international collaboration, both for scientifi c research and post-graduate studies.

DESCRIPCIÓN DE LA MORFOLOGÍA DENTAL Y DEL HÁBITO ALIMENTARIO DEL BESOTE JOTURUS PICHARDI (MUGILIFORMES: MUGILIDAE)

The dental morphology of J. pichardi and its relation to dietary habits is described for the first time. This mugilid inhabits the torrential rivers of short course in the Sierra Nevada de Santa Marta, that quickly lead into the Caribbean Sea. Joturus pichardi has heterodont dentition, with different forms that vary according to the tooth containing structure. The observed tooth structure is typical of omnivorous fishes, and consistent with the structure and composition of the diet analyzed. The latter was found dominated by mosses and aquatic macro invertebrates, mainly Chironomidae, a family of Diptera.

Discovery of fossil Nemacheilids (Cypriniformes, Teleostei, Pisces) from the Tibetan Plateau, China

Here described are the nemacheilid fossils from the Pliocene Lower Member of Qiangtang Formation in the Kunlun Pass Basin, northeastern Tibetan Plateau, at a locality 4769 m above the sea level (a. s. l.). The materials consist of numerous disarticulated and incomplete bones. The fish remains are assigned to the Nemacheilidae based on the fused compound centrum of the 2nd and 3rd vertebrae with developed bifurcate lateral processes of the 2nd vertebra. The fossils also include the maxilla, the dentary, the anguloarticular, the quadrate, the hyomandibular, the opercle, the basihyal, the urohyal, the anterior ceratohyal, the posterior ceratohyal, the interhyal and the supracleithrum. These bones are very similar to their counterparts in some species of a Recent nemacheilid genus, Triplophysa (Nemacheilidae, Cypriniformes), which is widely distributed on the Tibetan Plateau. The nemacheilid fossils are much more abundant than the remains of schizothoracines embedded in the same horizon at the same locality. This would imply that the number of individuals of Triplophysa was much higher than that of schizothoracines when they were alive in the area. In Recent ichthyofauna of the Tibetan Plateau, Triplophysa prevails over schizothoracines in the number of individuals in the high elevations and small water bodies. Based on the fossil dominance of Triplophysa over schizothoracines and their taphonomical conditions, it appears that the water system at the Kunlun Pass area during the Pliocene might not be extensive lakes or large rivers with broad valleys. There might have been a few mountainous, relatively torrential rivers with many small, shallow streams connecting the water systems from the north and south of the East Kunlun Mountain. The environment of the Kunlun Pass Basin area during the Pliocene must be very harsh, and the altitude of the area might already have been higher than we previously suggested. The uplift of the area must be less than 1000 m since the Pliocene.

Periphyton as a bioindicator of mercury pollution in a temperate torrential river ecosystem

Mercury presents a potential risk to the environment and humans, especially in its methylated form. It is among the highest priority environmental pollutants. River Idrijca (Slovenia) is highly contaminated with mercury due to past mercury mining. The aim of this work was to investigate whether the periphyton community in rivers such as Idrijca is a suitable indicator of Hg pollution and of changes in mercury methylation and could serve as an early warning system of increased input of MeHg in the food chain. Periphyton is the only site of primary production in temperate torrential rivers such as Idrijca and is therefore an important link in the food chain. It is also a potential site of Hg accumulation and its introduction to higher trophic levels. Our aim was to assess the response of the periphyton to seasonal and spatial variations in mercury levels and to evaluate its potential as an early warning system of changes in mercury reactivity and mobilization The results indicate that periphyton in a torrential river is too complex and unpredictable to be used as a sole indicator of mercury concentrations and changes in the river. Nevertheless, it can complement environmental measurements due to its importance in the riverine food web.

Mitigating the catastrophic impacts of torrential rivers in semi-arid environments: a case of the Gash River in eastern Sudan

The climatic, geomorphic, hydrologic and aquifer characteristics of the torrential Gash River across mountainous areas, in far eastern Sudan, were analyzed in order to mitigate its recurring catastrophic impacts. Hydrologic and climatic data and interpretation of Gash River satellite images were from relevant research works carried out in Gash Basin from 1985 to 2008. The results indicated that the total catchment area of Gash River is about 21,000 km 2 , and the basin area is 31,000 km 2 . The total length of Gash River is 450 km and the average slope is 200 cm/km. The width of the catchment varies from 30 m to 90 m and that of the basin is from 100 m to 800 m, and the course of the river is varied. During the period of 1980−2008, the mean annual rainfall was 250 mm and the mean annual discharge was 6.8 × 10 8 m 3 , and the flooding is approximately one time per 5 years. Torrential floods measured at Kassala town since 1907 showed that an absolute maximum discharge was 876 m 3 /s and a mean maximum discharge was 365 m 3 /s. These characteristics differ widely between catchment and basin areas. The author proposes that, by analyzing the climatic, geomorphic, hydrologic and aquifer characteristics of the Gash River and considering the role of community, a concise database could be provided to formulate the aquifer, geo- morphic, hydrologic and climatic (AQUIGEOHYCLIM) regional approach to mitigate Gash River recurring catas- trophic impacts.

A volcaniclastic deep-sea fan off La Réunion Island (Indian Ocean): Gradualism versus catastrophism

A new geophysical data set off La Reunion Island (western Indian Ocean) reveals a large volcaniclastic submarine fan developing in an open-ocean setting. The fan is connected to a torrential river that floods during tropical cyclones. Sediment storage at the coast is limited, suggesting that the sediments are carried directly to the basin. The fan morphology and turbidites in cores lead us to classify it as a sand-rich system mainly fed by hyperpycnal flows. In the ancient geological record, there are many examples of thick volcaniclastic successions, but studies of modern analogues have emphasized mechanisms such as debris avalanches or direct pyroclastic flow into the sea. Because the Cilaos deep-sea fan is isolated from any continental source, it provides information on architecture and noncatastrophic processes in a volcaniclastic deep-sea fan.

The impact of late Holocene climatic variability and land use change on the flood hydrology of the Guadalentín River, southeast Spain

The Guadalentín River, located in southeast Spain, is considered one of the most torrential rivers in Spain, as indicated by catastrophic events such as the 1879 flood that caused 777 fatalities in the Murcia region. In this paper, flood frequency and magnitude of the upper Guadalentín River were reconstructed using geomorphological evidence, combined with one-dimensional hydraulic modelling and supported by records from documentary sources at Lorca in the lower Guadalentín catchment. Palaeoflood studies were conducted along a 2.5-km reach located at the confluence of the Rambla Mayor (162 km 2) and Caramel River (210 km 2). These tributaries join at the entrance of a narrow bedrock canyon, carved in Cretaceous limestone, which is 15–30 m wide and 40 m deep. Six stratigraphic profiles were described, the thickest and most complete corresponding to flood benches deposited upstream of the canyon constriction. The stratigraphic and documentary records identify five main phases of increased flood frequency. Phase 1, based on sedimentary palaeoflood evidence alone, occurred at c. AD 950–1200 with at least ten floods with minimum discharge estimates of 15–580 m 3 s − 1 . Phases 2–5, identified through combined sedimentary and documentary evidence occurred at: (a) AD 1648–1672, with eight documentary floods and two palaeofloods exceeding 580–680 m 3 s − 1 (most probably the AD 1651 and 1653 events); (b) AD 1769–1802, comprising seven documentary floods, of which at least two events (> 250 m 3 s − 1 ) are preserved in the sedimentary record; (c) AD 1830–1840, with four documentary floods, and at least two events recorded in the stratigraphy (760–1035 m 3 s − 1 ); and finally (d) the AD 1877–1900 period that witnessed seven documentary floods, with three palaeofloods exceeding 880 m 3 s − 1 . The palaeoflood and historical flood information indicate an anomalous increase in the frequency of large magnitude floods between AD 1830 and 1900, which can be attributed to climatic variability accentuated by intensive deforestation and land use practices during the first decades of the nineteenth century.

Geomorphologic Methods for Estimating Flood Hazards in Mountain Catchments

This article presents the possibilities for implementation of the geomorphologic methods in estimation of the morphometric characteristics and relief dismemberment in flood hazard analysis for the Malki Iskar and Suha Reka river catchment above the town of Etropole. The results shown in the maps of the vertical and horizontal relief dismemberment in GIS exhibit a very high degree of conformity between the torrential river sections and the regions with high values of horizontal and/or vertical relief dismemberment.

Modelling a torrential event in a river confluence

Torrential floods characterized by extremely high discharges and sediment transport rates are common in Mediterranean areas. Few field data is available for such floods due to sudden increase in water discharges and short flood duration. This paper presents the field data collected during a major flood event in a 90° confluence of two torrential rivers of the Mediterranean area. A two-dimensional model was used to describe the flow characteristics at the confluence. The influence on water levels of the torrential character of both rivers and some morphological processes as the tributary mouth gravel bar has been assessed. Although channel roughness coefficients and sediment deposits influence final water surface elevations they have lesser effect than the discharge ratio between main and tributary rivers.

Heavy Metals in the Surface Sediments in Lanzhou Reach of Yellow River, China

The heavy metal pollution and their fractionations in the surface sediments of Yellow River in Lanzhou Reach was monitored for arsenic (As), lead (Pb), Zinc (Zn), chromium (Cr), copper (Cu) and manganese (Mn) with Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The mean sediment concentrations (in microg/g dry weight) ranged from 13.68-48.11 (As), 26.39-77.66 (Pb), 89.80-201.88 (Zn), 41.49-128.30 (Cr), 29.72-102.22 (Cu), and 773.23-1459.69 (Mn). Spatial distribution showed that each heavy metal concentration remained almost constant in this reach. Correlation coefficients indicated that metals were not strongly associated with sediment sand content or organic carbon content (f(oc)). Labile fractions (exchangeable + carbonate + Fe-Mn oxide) had no significant correlations with sand content or f(oc), either. Results from the present study are useful for understanding heavy metal distributions in a torrential river sediment environment.

Hydrological analyses in Skrapež river basin

Reasons for lack of hydrological studies in mountainous regions are: absence of hydrological measurements and the fact that measurements were not continuous. However, as mentioned areas are basic sources of fresh, unpolluted and useful water, it is necessary to carry out water regime researches and continuous measurements. Surface amount of water in Skrapež riverbed was analyzed, as well as its regime and water balance. Water management problems were pointed out as well. This paper discusses problems connected to decreasing of water amount in the last 20 years of analyzed period, variations of discharge, threats to economy in periods of both low and high water, and also points out the torrential character of the river. The possibilities of water usage from previously unstudied Skrapež sub basins are pointed out as well. Research and utilization of these sub basins provided that high water quality is preserved, would lead to high level of solving the problems of water supply, irrigation and torrential rivers.

On the determination of the stable bed slope of a channel using mathematical model

The paper deals with an analysis of selected equations used for the determination of a stable longwise slope calculation of torrential rivers. Irregularity of the gradient, accompanied by heavy bed-load experiencing abrupt changes of the flow as a result of heavy rainfalls of short duration and high intensity, these are typical features impacting the behaviour and characteristics of torrential rivers. The determination of the stable bottom slope, when the river bed is kept unpaved but still provides resistence against harmfull effects of rapids, becomes an essential objective of the study. Three methods are used to determine the stable slope: the first is based on tangent tension (shear stress theory), the second observes a (critical) non-scouring cross-sectional velocity (critical mean channel velocities), and the third applies the bottom layer velocity, (the critical bed velocities). The mathematical hydraulic model HEC-RAS v. 3.1.3 has been used for the verification of the methods in the Jindřichovický creek case study in the Krušné hory.

Bioaccumulation of mercury in benthic communities of a river ecosystem affected by mercury mining

The presence of mercury in the river Idrijca (Slovenia) is mainly due to 500 years of mercury mining in this region. In order to understand the cycling of mercury in the Idrijca ecosystem it is crucial to investigate the role of biota. This study is part of an ongoing investigation of mercury biogeochemistry in the river Idrijca, focusing on the accumulation and speciation of mercury in the lower levels of the food chain, namely filamentous algae, periphyton and macroinvertebrates. Mercury analysis and speciation in the biota and in water were performed during the spring, summer and autumn seasons at four locations on the river, representing different degrees of mercury contamination. Total (THg) and methyl mercury (MeHg) were measured. The results showed that the highest THg concentrations in biota correlate well with THg levels in sediments and water. The level of MeHg is spatially and seasonally variable, showing higher values at the most contaminated sites during the summer and autumn periods. The percentage of Hg as MeHg increases with the trophic level from water (0.1-0.8%), algae (0.5-1.3%), periphyton (1.6-8.8%) to macroinvertebrates (0.1-100%), which indicates active transformation, accumulation and magnification of mercury in the benthic organism of this heavily contaminated torrential river.

Geomorphological characteristics of the sand-dune field of the central Kyparissiakos Gulf

Sand dunes are sensitive coastal landforms closely related to the evolution (and/or stability) of the beach zone. The present work refers to the central part of the dune field that lies along the middle part of the shoreline of the Kyparissiakos Gulf. The scope of the present investigation is to reveal the geomorphological and sedimentological characteristics of the sand dune field in association with the natural processes contributing to their formation. On the basis of our findings, the dune field of the central Kyparissiakos Gulf consists of four dune ridges, with heights >4.0 m. Their extent indicates the availability of large quantities of sand and the existence of a rather stable wind field. They consist of well sorted medium to fine sand. The alluvial fan of the Zachareiko torrential river has covered the dune field in the area of its mouth and buried the oldest 4th dune ridge to its south. The development of the dune field is estimated to have taken place during the last 3-4 thousand years subsequently to the completion of the rapid sea level rise at the end of the last glacial period.

Holocene paleogeographies of the Palairos coastal plain (Akarnania, northwest Greece) and their geoarchaeological implications

AbstractSediments from the Palairos coastal plain (Akarnania, northwest Greece) were studied to establish paleogeographical scenarios of Holocene landscape evolution. Near coast vibracore profiles revealed regressive sedimentary sequences, the base of which is dominated by marine sand and/or lagoonal mud. The middle and upper parts of the sequences are made up of lacustrine mud and fine‐ to coarse‐grained alluvial deposits reflecting the increased activity of torrential river systems. In the southern plain, marine sediments of the maximum incursion of the Ionian Sea were found 1 km inland and date from the seventh millennium B.C. This proves that the Lake Voulkaria in the northern plain does not represent the remains of a former marine embayment. Subsequently, a large lagoon developed and existed until the fourth millennium B.C. The central plain was mainly exposed to subaerial conditions when man started to colonize the area in the seventh millennium B.C. In the fifth millennium B.C., the Palairos lagoon turned into a freshwater lake. When ancient Palairos was founded in the 6th century B.C., shallow lakes and swamps dominated the southern and central parts of the plain. At that time, a narrow canal‐like connection between the Bay of Palairos‐Pogonia and the Lake Voulkaria existed and was possibly used as a slipway for ships. During the last 4000 years, the Palairos plain experienced strong input of fluvial sediments which finally filled up the coastal lake as well as the swampy grounds. © 2006 Wiley Periodicals, Inc.

Restoration of an urban river in Barcelona, Spain

The paper describes the “environmental recovering” of the Besos River, a torrential river flowing through the urban area of Barcelona. An overview of river history and current problems and the aims and social constraints for the restoration are presented. After that, the design of a meandering low flow channel within the floodway is dealt with. Constructed wetlands to improve water quality were planned for the floodplain on both sides of this channel. Scale models, fixed-bed and mobile-bed, were then built to test the floodway conveyance and the risk of scour or deposition in it.

Filling and plugging of a marine basin by volcanic rocks: the Tunoqqu Member of the Lower Tertiary Vaigat Formation on Nuussuaq, central West Greenland

The volcanic Tunoqqu Member formed at the end of the second of three volcanic cycles in the Paleocene Vaigat Formation. The Tunoqqu Member consists of brown aphyric and feldspar-phyric basalts and forms a marker horizon within the grey picritic rocks of the Vaigat Formation. Most of the basalts are siliceous and were produced by contamination with crustal rocks of magmas ranging in composition from picrite to evolved basalt. Some of the basalts were erupted from local volcanic centres of which four have been identified, whereas other basalts form more regional flows. The four identified eruption centres are located along fault lines and zones of uplift and subsidence, indicating tectonic control. Tectonic control is also inferred to be important in terminating the volcanic cycle and causing the development of high-level magma chambers where the magmas stagnated, fractionated, and became contaminated. The basalts of the Tunoqqu Member form subaerial lava flows in western Nuussuaq. Central Nuussuaq constituted a marine embayment in which the volcanics were deposited as eastward prograding foreset-bedded hyaloclastite breccia fans which indicate water depths of up to 160 m. Eastern Nuussuaq was a gneiss highland with a more than 700 m high NW-SE-elongated gneiss promontory stretching into the sea. During Tunoqqu Member time the volcanic rocks reached the gneiss promontory and blocked the outlet from the south to the sea in the north. This resulted in increased water levels in the enclosed embayment and transformation of the outlet into a torrential river. This river eroded the concomitantly forming Tunoqqu Member volcanics and the gneiss promontory and deposited the material in up to more than 250 m thick foreset-bedded boulder conglomerates in the sea where the north coast of Nuussuaq is now situated.

Composition of torrential river sediments from ne of Spain

The composition of sediment samples from the rivers Lea, Oria and Bidasoa (NE of Spain) has been determined by analytical procedures (AAS and FIA) and size fraction analysis. Measured parameters include major (organic carbon, Cationic exchange capacity, carbonates, Na, K, Ca, Mg, Si, Al and Fe) and microconstituents (Cu, Zn, Mn, Pb, Ni, Cr and Cd). Results for total and fine (< 63 microns) samples are discussed by conventional and multivariate (factor and cluster analyses) statistical techniques.