High Waterfall Research Articles

Numerical modeling of the impact of a large scale waterfall on a solid plate

Recent hydroelectric power plant safety developments have necessitated detailed studies on dam spillway operations, especially during emergency water discharge scenarios such as overtopping. This paper presents a numerical investigation of a 10-meter high waterfall impinging on a solid plate using two-phase flow models. Our approach integrates a coupled Eulerian–Lagrangian Spray Atomization (ELSA) model with an Interface Capturing Method (ICM) to simulate the complex multiphase flow and atomization processes. Our model proficiently mapped the velocity and turbulence within the pre-impact region. To refine the accuracy of the impact pressures, we isolated this zone and implemented the Injection–Reinjection strategy, a novel numerical procedure for this type of configuration. The study reveals significant insights into the dynamic interactions of water packets with the dam structure, highlighting critical impact pressures that can influence dam stability and integrity. Our results, compared against experimental data, demonstrate the effectiveness of the modeling strategies in predicting the fluid behaviors and the subsequent pressures exerted on structural components.

Potensi Pengembangan Mikro Hidro Sungai Pasak Suling Kabupaten Gunung Mas Kalimantan Tengah

Community in Desa Karason Raya District Tewah have no access to the State Electricity Network (PLN), when electricity is needed for development in this village. Karason Raya Village has potential of water resources that can be used as a generator of Micro Hydro Power Plant (MHPP) but these resources are not optimally explored. This study aims to determine the socio-economic conditions, geological conditions, hydrology. The amount of power that can be provided by the Micro Hydro Power Plant (MHPP) and the strategies when the Micro Hydro Power Plant (MHPP) wll be developed by SWOT Analysis. Research is done in Desa Karason Raya District Tewah. Methodology used was secondry data analysis, interviews, and field observations to obtain the necessary data. Results showed that the type of Malihan Pinoh rock (PzRp) composed of fillit , kis, quartize and genealogy. The slope of ground conditions along Sungai Pasak suling tributary quite steep on both the river are rocky hills that are not symmetrical. Calhmet wide area 7.50 Km², 1.30 m³/sec measureable water discharge, 13 metres high water fall and potential generated power of 168.339,60 watts

Beyond waterfalls and dams: Riverscape genetics of two endemic mountain loaches in the Western Ghats biodiversity hotspot

AbstractRiverscape genetics of fish, though extensively studied in temperate regions, have received limited interest in tropical rivers, especially in montane systems which not only harbour several endemic and threatened species, but are also subjected to extensive habitat modifications. We determine the population genetic structure of two endemic balitorid loaches (Bhavania australis and Travancoria elongata) in response to natural (25 m high waterfall) and artificial (23 m high and 290 m long hydropower dam) barriers in a small mountain riverscape in the Western Ghats Hotspot. Population genetics analysis using mitochondrial cytochrome b gene sequence showed low nucleotide diversity, haplotype diversity and genetic differentiation among populations, for both species, suggesting that barriers did not influence genetic structuring. Though migration analysis also revealed that barriers did not affect movement of the two species through the riverscape, patterns in mutation‐scaled immigration rates and population sizes differed between the two species supporting our observation that they rarely co‐exist in the same habitat, likely as an effect of competitive exclusion. Mismatch distribution and Bayesian skyline plot suggested recent expansion in the populations of B. australis and corresponding population decline in T. elongata in the last 100 years, which probably explains the widespread and abundant distribution of B. australis as opposed to the narrow endemism and rarity of T. elongata. Our results provide novel insights into the ecology of balitorid loaches and their response to riverine barriers in a tropical mountain landscape.

Design of a prime mover turbine propeller open flume micro-hydro electric power plant 1 kW

West Java has many rivers that have high falls and varied water discharges where utilization is not optimal. The study aims to utilize water energy to be able to produce a Micro Hydroelectric energy generator. The design of this PLTMH starts from measuring the potential of water, designing turbines and generators, then observing the work system of PLTMH and estimating the electric power that will be generated by the PLTMH. From chosen location, it is known that the water flow is 0.0059 cubic per second and has a waterfall height of 4 meter. This data is used to select the type of turbine, selection of reservoirs, rapid piping, and generator design. The results obtained by the design of Micro Hydro Power Plant (PLTMH) using open flume propeller turbines and 3-phase generators are changed to 1 phase. Open flume propeller turbines have a simple construction and can be operated at a waterfall height of 3-6 meters and low water discharge so that the use of open flume turbines for micro-hydro power plants will be used in river flows that have high waterfall and water discharge the low one is very appropriate. With a turbine rotation speed of 2,063 rpm, this PLTMH is capable of producing 1,346 watt turbine power with a 45 liter per second water flow so that the power obtained is 1,076 watt.

PENGARUH TEKANAN AIR DAN SUDUT NOZZLE TERHADAP KARAKTERISTIK OUTPUT PADA PROTOTYPE PLTMH DENGAN TURBIN PELTON

Pelton turbine is an impulse turbine that is different from other turbines where the peltonturbine utilizes a large high water fall (head), even with a small water discharge. The problemwith Pelton turbine is that the head is still difficult to control because this type of turbine uses ahigh head to rotate the turbine runner and there is no formula / equation to determine the angleof the nozzle which produces maximum output. Based on the problems described, it isnecessary to make a micro hidro power plant prototype using a pelton turbine with a laboratoryscale so that it can do the testing of the influence of water and the nozzle angle to obtainmaximum output results on a micro hidro power plant using a pelton turbine. The prototypetesting in this study used various water pressures, namely 5 psi, 9 psi, 13 psi, 17 psi, 21 psi,and 25 psi with nozzle angles, namely 60º, 75º, and 90º. Based on the results of the study, anincrease in the value of water pressure provided with an optimal nozzle angle will cause themicro hidro power plant performance to increase. The maximum output obtained is when thewater pressure is 25 psi with a nozzle angle of 90º which produces a turbine rotation of 917 rpmbefore the generator is coupled and 326 rpm after the generator is coupled, the generatorrotation is 1321 rpm, the generator voltage is 12.9 Volts, generator power is 30.96 Watt, torque is 0.98 Nm, and the highest efficiency occurs when the water pressure is 21 psi with a nozzleangle of 90º which is 3.91%.

Karakteristik Unjuk Kerja 2 Pompa Sentrifugal Dengan Susunan Seri Sebagai Turbin Pat

The pump is a device used to move fluid from one place to another through a media pipe or channel. The energy in the fluid is produced from the impeller which converts the kinetic energy (velocity) of the liquid into potential (dynamic) energy. Besides being used to move fluid (fluid) at this time the pump can also be used as a turbine by changing the working principle of the pump by giving a drop of water at an altitude to rotate the impeller on the pump so that the pump can operate upside down or called a pump as turbine), in this study the impeller on the pump as a turbine is driven by a water flow or water pressure that is large enough, the water flow is sourced from two centrifugal pumps with a series arrangement that functions as a driving force or fluid distributor which is assumed to be a high water fall or head. The use of centrifugal pumps with a series arrangement is so as to produce a large head to get a high water fall or a maximum head for turning a pump as a turbine. This study uses an experimental method that is using two centrifugal pumps as a fluid distributor and one pump that is used as a turbine and uses a variation of 5 watt and 10 watt light bulb. From the calculation of the suction pump and pump as a turbine without using a light bulb pump speed namely 920.5 rpm and the specific speed of the turbine produced is 76.61 rpm. by using a 5 watt light bulb load the pump rotation speed is 553 rpm and the specific turbine speed produced is 44.24 rpm, using a 10 watt light bulb load the pump rotation speed is 335 rpm and the specific turbine speed produced is 26.8 rpm. The greater the value of the pump head, the resulting water discharge will be smaller and vice versa, the size and size of the pump head obtained is also influenced by the presence of load on theturbine.

RANCANG BANGUN PEMBANGKIT LISTRIK TURBIN AIR MIKRO HIDRO TIPE CROSS-FLOW KAPASITAS 2.500 WATT Di Kp. MULYASARI -BOGOR JAWA BARAT

To meet the electricity needs at night and the production of agricultural products in Kp. Mulyasari was designed and built a Micro Hydro Power Plant (PLTMH) Turbine which can produce power up to 2,500 Watt. This machine is designed to be easy to install, easy to operate, inexpensive to maintain. The selected turbine type is a Cross-Flow air turbine for a low head. Turbines operate at impulse pressure, where the potential energy of water is converted into kinetic energy through the nozzles to push the turbine's front blades. In the design of this turbine, it is designed, so that it has a long life span, low investment value, minimal maintenance costs, easy installation costs, and is driven by water, thereby conserving natural resources. The turbine is designed based on data from field survey results in Kp. Mulyasari, with results; Head (H) = 1.85 m; Water discharge (Q) = 0.2 m3 / s; Turbine rotation (planned) (n) = 214 rpm; Turbine efficiency (plan) (ηt) = 68%; Density of water (ρ) = 997.8 kg / m3. From the calculation results, obtained the Cross-Flow turbine design specifications as follows: High waterfall (H) = 1.85 m; Water discharge (Q) = 0.2 m3 / s; Turbine efficiency (plan) (ηt) = 68%; Power (N) = 2,497 kW; Rotation (n) = 214 rpm; Specific speed (ns) = 770,4138831 rpm; Road blade diameter (DL) = 0.40 m; Naaf diameter (Dn) = 0.035 m; Steering blade width (B) = 0.032 m; Number of road blades = 26 pieces.

Macroinvertebrate benthic community as rapid quality assessment in Winongo, Code, and Gajahwong Streams inside Yogyakarta City, Special Region of Yogyakarta Province

Streams in Yogyakarta City are classified as an urban river, they receive huge amount of organic matter daily from anthropogenic waste. Growing urbanization affected water ecosystem causing water quality and benthic community changes. Macroinvertebrate benthic immediately respond to physic-chemical changes of the stream. Aims of this study are studying urbanization alter macroinvertebrate benthic community, and water quality in Winongo, Gajahwong, and Code streams of Yogyakarta City. Samples were collected at December 2015 and January 2017 in Winongo, Gajahwong, and Code streams inside the administration area of Yogyakarta City using sediment Dredge. Collections perform by dividing each stream into three parts with five replications. Macroinvertebrate benthic were filtered using stratified filter mesh 60, 40, and 20 results showed that macroinvertebrate benthic diversity decreasing from 2015 to 2017 in these three urban streams. There were not much species founded in Yogyakarta City Streams, indicates riparian ecosystem lack of natural habitat. All riparian zone are damage by anthropogenic activities. Their density is also decreasing probably because riparian floodplain embankment caused water velocity faster, leave little sediment for benthic organism. Chironomids larvae dominate in all stations in each river, and the most abundant in Code. They were abundant because streams in Yogyakarta City accept high input of organic matter. They classified as tolerate groups where their abundance indicates water pollution. High waterfall during 2016 most probably caused water quality better in 2017 than 2015. Dissolved oxygen was higher, and water ph is closer to neutral. Thus it cannot be used as an indicator.

EKSISTENSI PLTMH CINTA MEKAR DALAM PEMBERDAYAAN MASYARAKAT MELALUI KOPERASI MEKAR SARI DI DESA CINTA MEKAR KECAMATAN SERANG PANJANG KABUPATEN SUBANG PROVINSI JAWA BARAT

PLTMH located in CintaMekar Village, SerangPanjang Sub-District, Subang Province, West Java Province, utilizes Ciasem River water, processed so that it has high water fall 17,61 m, water discharge design 1,100 l / s, hydraulic potential of 160 KW, turbine efficiency of 0.73, efficiency of generator 0.89, out put generator 120 KW, loses 4 KW and total electrical energy generated 116 KW. The purpose of development, to help people who were not reached PLN electricity, to empower the community.Empowerment begun from the time of development, where citizens are involved, which then able to become operators. The result of energy from PLTMH is sold to PLN, then the result is reduced for operational costing, maintenance cost, import cost / electricity payment used, depreciation cost of equipment taken from 10% of transactions, divided by two (50% for PT HidropirantiIntiBaktiSadaya, as shareholder) and 50% for Mekar Sari Cooperative, used for community empowerment. Since its operation, people who do not have electricity grid, are connected to electricity. In addition, the proceeds from the sale of electricity to PLN are used to help with the cost of education / scholarship, health, loans for business and cooperative operations. Empowerment implemented or managed Mekar Sari Cooperative. Along with the development of the era, empowerment assistance now being implemented includes: Health Sector in cooperation with Village Midwife, Savings and Loans and Scholarships for Primary School - 10 People and Junior High School - 5 People. Keywords: Potential Water Resources, New and Renewable Energy Power, PLTMH Cinta Mekar, Mekar Sari Cooperative, Community Empowerment

OPTIMIZATION OF THE FEASIBILITY OF MICRO HYDRO POWER PLANT (PLTMH) RAMPUSA SUB DISTRICT OF LEMBANG REGENCY PINRANG

Economic growth and basic electrical energy pentarifan (TDL) that is determined by the Government and PLN is the thing that most affect the usage/consumption of electrical energy, as in the theory of microeconomics, the demand for a commodity including energy electricity is influenced by various factors, including the following: the requested prices of goods, the prices of other goods, income, tastes and prosperity. The provision of electricity is not only meant as a tool for tackling poverty, but also dimaksdukan for equitable development and advance the villages as a force for the national economy. Therefore to meet the need for electric lighting for remote areas need to be created a tool that can reach remote places that are cheap and environmentally friendly, that micro hydro power plant. This research aims to know the feasibility of Micro Hydro power plant Rampusa sub district of Lembang Regency pinrang. This research is the research of ex-post-facto that is descriptive. The sample in this research is to look at the technical aspects of PLTMH. As for side input consists of water discharge (Q) effective falls high (H), the State of the generator, turbine, form the type of pipeline and the turbine House (power house). As for the Power output is generated (P), Village PLTMH rampusadan load Protection installed. The result of the research of the optimization of the feasibility of Micro Hydro power plant Rampusa sub district of Lembang Regency Pinrang, with discharge water 0.17 m3/sec, 23 m high waterfall with a power generator with a capacity of kW 26.04 20 kVA, kVA 32.55 should use by using different types of crossflow turbine the turbine type France should use, type of PVC pipe 12 "which is above the soil surface that is supposed to be planted in the ground, a burdens attached 23980 VA and cable distribution is used. So a descriptive analysis of the results showed that PLTMH rampusa Village sub district of Lembang Regency Pinrang not feasible from a technical point.

ORACLES ON FAULTS: A PROBABLE LOCATION OF A “LOST” ORACLE OF APOLLO NEAR OROVIAI (NORTHERN EUBOEA ISLAND, GREECE) VIEWED IN ITS GEOLOGICAL AND GEOMORPHOLOGICAL CONTEXT

At a newly discovered archaeological site at Aghios Taxiarches in Northern Euboea, two votive inscribed stelae were found in 2001 together with hellenistic pottery next to ancient wall ruins on a steep and high rocky slope. Based on the inscriptions and the geographical location of the site we propose the hypothesis that this is quite probably the spot where the oracle of “Apollo Selinountios” (mentioned by Strabo) would stand in antiquity. The wall ruins of the site are found on a very steep bedrock escarpment of an active fault zone, next to a hanging valley, a high waterfall and a cave. The geomorphological and geological environment of the site is linked directly to the regional geodynamical context of Central Greece, a region of tectonic turmoil throughout the Pleistocene and Holocene, characterised by distinct landscapes produced by the activity of active fault zones, intense seismicity, and in part, volcanism and hydrothermal activity. The geomorphological and geological similarities of the Ag. Taxiarches site with those of the oracle at Delphi, seem to provide further support to the hypothesis that the former site can well be that of an ancient oracle, given the recently established connections between the geological environment at Delphi and Apollo’s oracle there. Definitive verification of our hypothesis can only be obtained by further, detailed archaeological study, whereas geological/geomorphological, geochemical, and geochronological studies would be necessary to clarify the connection that the cave lying next to the wall remains may had with the site’s function.

The development of a pulsating supraglacial stream

ABSTRACTSupraglacial streams are a significant part of the glacial hydrological system and important for understanding the connection between glacial hydrology and glacier dynamics. Here we determine the factors that influence the development of step-pool formation and pulsating flow in a supraglacial stream on Bylot Island, Nunavut. Results show that during the second week of a 2-week study, multiple successive rainfall events occurred, stream temperature increased and ablation decreased; which also caused stream discharge to decrease. In addition, the stream, which flowed over a 13 m high waterfall off the front of Fountain Glacier, rapidly formed 21 step-pools and began to pulsate. The pulsating phenomenon involved the complete stoppage of flow over the waterfall and the subsequent restart between 8 and 20 s later. Pulsating flow resulted from rapid changes in the streambed morphology. In particular, the formation of the step-pool sequence was caused by helical flow around meander bends and hydrologically induced slippage along transverse shear planes, evidenced by observations of high-pressure artesian flow from transverse fractures. Contrary to previous literature, this study shows that high discharge is not necessarily the cause of step-pool formation and pulsating flow within supraglacial streams.

Effect of waterfalls on fluvial fish distribution and landlocked Rhinogobius brunneus populations on Yakushima Island, Japan

The distribution of fluvial fish was surveyed at 55 sites on Yakushima Island, Japan, which has precipitous mountains and waterfalls (below- or no-waterfall sites: 31; above-waterfall sites: 24). Eleven diadromous and one river resident (introduced Oncorhynchus masou masou) species were found, but absolutely no fish were detected at the 18 above-waterfall sites. Statistical analyses revealed that the presence of waterfalls (> 5 m in height) below the sites had a significant negative effect on fish distribution, suggesting that waterfalls prevent migration of diadromous fishes. We found Rhinogobius brunneus populations above high waterfalls such as Nunobiki Falls (50 m) and Ohko Falls (88 m). Otolith Sr:Ca ratios and mitochondrial DNA (cyt-b region) were examined to determine the migratory history and genetic properties of these populations; the Sr:Ca ratios indicated that the populations had a landlocked life cycle, whereas the genetic endemism/isolation of landlocked populations was unexpectedly absent. There is no clear explanation for this phenomenon, but fairly infrequent individuals of nonlandlocked type might have migrated beyond the waterfalls with their sucker-like organ and mated with landlocked populations, disrupting the genetic isolation of landlocked populations.

ANALISA PENGARUH VARIASI SUSUNAN TERHADAP KEMAMPUAN UNJUK KERJA POMPA HYDRAM DITINJAU DARI ASPEK TINGGI TERJUNAN AIR

Cultivation activities, both in the development of food crops, horticulture, livestock and plantations. Availability of water is a strategic factor. Specific areas adjacent to the water source or location are under the eyes water, water needs are less of a problem. However, the ground reality is not always flat; there is the hilly or bumpy. Land surface area is higher than the water source and the bumpy areas will have trouble getting a continuous supply of water. Therefore need to find an alternative to reduce the burden. One alternative is that hydram pump hydraulic work without using gasoline. Hydram pump was applied to a small debit them to raise water and drinking water needs of households. However, the use for irrigation in dry land agriculture that requires a large output flow is unknown. The method used in this research is to create models in the laboratory to simulate the independent variables of pressure (high falling) water flow while bound variables measured include debit and results of hydraulic pressure. The results of experiments that analyzed the correlation between independent variables and the variables are bound to get hydram pump efficiency. Pumps that were realized and tested in the laboratory have the following specifications: input = 1.5 inch diameter; output diameter = 0.5 inches; step on the valve piston waste = 5 mm; air tube diameter = 3 inches; air tube length = 24 cm ; material with galvanized pipe, construction of hydram pump consisting of the first arrangement of input - waste valves - compressor (ILK) and the second arrangement of input - compressor - waste valve (IKL). Pump of hydram with arrangement ILK has the ability to better performance when compared with the composition of IKL. Where pump of hydram with the composition of ILK has the best efficiency at 2.5 meters high waterfall with a debit enter 2.458 liters / sec discharge output capable of being lifted by a pump at 0087 liters / sec while the high lift or vertical height of the pump which is equal to 30 meters and efficiency pump of hydram which is equal to 13.6%.

Population structure analysis of Pimelodus maculatus (Pisces, Siluriformes) from the Tietê and Paranapanema Rivers (Brazil)

Pimelodus maculatus populations from the Tietê and Paranapanema rivers were sampled and had their genetic structure analyzed by using RAPD markers, with the aim of contributing to future conservation studies. The proportion of polymorphic loci was greater than 50% in the populations of both rivers. Genetic diversity data showed that, in spite of its nine hydroelectric plants, the Tietê river population was genetically homogeneous, whereas the Paranapanema river population was structured. This might be due to the presence of high waterfalls distributed all along its course. These data may serve as indicators for future conservation studies on the Tietê and Paranapanema rivers.

Genetic differentiation among populations of the amphidromous shrimp Atya innocous (HERBST) and obstacles to their upstreaming migration

In order to determine whether the amphidromous shrimp Atya innocous can breed successfully in freshwater above major obstacles to its upstream migration, we investigated the reproductive interactions among three local populations above high waterfalls or stream sections without runoff in Guadeloupe, Lesser Antilles. Reproductive interactions were investigated through the rates of genetic divergence (based on 8 allozyme loci) between populations. We also investigated four populations from streams without major obstacles. We recorded a high level of dispersal (N m >13) between six local populations (from streams with or without major obstacles) resulting in the mixing of alleles (pairwise F st values never significantly different from 0). Major obstacles did not separate upstream populations from those of neighbouring drainage basins and our results did not support the hypothesis that A. innocous can breed successfully in freshwater. As stressed elsewhere, shrimps (and particularly juveniles) are probably able to climb high waterfalls. Moreover, they probably use subsurface passages to colonise upstream sections of certain rivers. On the contrary the seventh population (from a more distant stream without major obstacles) displayed a high degree of genetic differentiation (pairwise F st >0.8, P<0.001). The detailed mechanism of its reproductive isolation remains to be solved. According to the published literature on decapods, the genetic distance recorded (mean D = 0.278) between the two groups of A. innocous in Guadeloupe falls within the range of sub-species.

Simulating time-varying cave flow and water levels using the Storm Water Management Model

The Storm Water Management Model (SWMM) is an Environmental Protection Agency code used to estimate runoff through storm water drainage systems that include channels, pipes, and manholes with storage. SWMM was applied to simulate flow and water level changes with time for a part of Stephens Gap Cave in Jackson County, Alabama. The goal of the simulation was to estimate losses from a surface stream to the cave. The cave has three entrances that can remove water from the surface stream. These entrances connect through several passages to an 8-m (27-ft) high waterfall in a dome room. After a storm, the walls of this dome room had leaves on the wall as high as 4.6 m (15 ft) above the floor. The model showed that the height of the leaves did not represent a water level that could have occurred following any recent storm. Campbell, Livingston and Garza in 1997 developed the CLG model to estimate losses from karst surface streams. This model treats losses as pipe flow from a reservoir and gives the loss flow rate as ∼ h 0.5 where h is the depth of flow in the surface stream. Losses to Stephens Gap Cave calculated with SWMM varied as h 1.8. This depth dependence is more characteristic of flow over a weir than of pipe flow. The SWMM-calculated losses to Stephens Gap Cave showed no hysteresis, that is, the rising and falling limbs of the stage-discharge plot followed the same curve. Loss curves with significant hysteresis are difficult to simulate with simple models such as CLG or a weir flow model. However, an SWMM model of a simple hypothetical cave demonstrated that storage in Stephens Gap Cave is far below that required to cause hysteresis. Losses from many karst surface streams can probably be adequately estimated with a calibrated weir flow model. The utility of SWMM for analyzing cave flows was established. SWMM produced stable solutions with very low continuity errors for this cave.

Coleopteran diversity and abundance in different habitats near Kihansi waterfall, in the Udzungwa Mountains, Tanzania

Coleoptera diversity at the family level was investigated along the Kihansi gorge near a 700 m high waterfall system which will be taken to hydropower use, and the current river flow will be diverted due to dam construction. The coleopteran communities of three micro-habitats: spray zone, forest site and riverine site were compared by sweepnetting and pitfall trap methods. The highest Coleopteran family level diversity was found in the spray zone where the Shannon–Weaver index of diversity was 0.71 (forest site 0.31; riverine site 0.50). Coleopterans were most abundant in the forest site where 44% of all sampled individuals were found (spray zone 31%; riverine site 23%). Most of less frequently recorded families were found in the spray zone. Coleoptera families were found to be unequally partitioned in all three micro-habitats. The highest percentage similarity index (85%) was found between forest and riverine sites (spray/forest 76%; spray/riverine 79%). Distributions of abundances of coleopteran families were significantly different between all studied habitats. The study revealed that the spray generated by the waterfall provide a special micro-habitat for Coleoptera. It is suggested that conservation efforts and monitoring in the study area using selected taxonomic indicator Coleopteran groups should be carried out in order to help to adjust mitigation measures.

Le karst haut alpin du Kanin (Alpes juliennes, Slovénie-Italie). Etat des connaissances et données récentes sur le fonctionnement actuel et l'évolution plio-quaternaire des structures karstiques

The high-alpine Kanin karst (Julian Alps, Slovenia-Italy). State of knowledge and new data on present functioning and plioquaternary evolution of the karstic structures. Kanin is a high-alpine karst located in the Italo-slovenian Julian Alps. Its surface was elaborated by the quaternary glaciers and includes some inherited discreet tertiary morphological features. Recent dye tracing has shown that the structural setting permits water infiltrated in Italian catchments to contribute to Slovene springs. Hydrodynamic and physico-chemical water analyses show extremely quick transfers of water during snow melt or heavy storms ; these create spectacular overflows, such as the Boka spring which emerges as a 100 m high waterfall. The phreatic zone, linked to the impermeable dam of the Soca valley, does not significantly slow these transfers. Nevertheless, it contributes to the occurrence of low water levels during recession periods, giving highly mineralised water after long resident periods. The presence of very deep and developed karst systems is explained by the combination of advantageous factors : thick and jointed limestone, important height gradient, and considerable precipitation. Paleomagnetic dating in one of the largest systems (Crnelsko brezno) attributes some glacial sediments to the Lower Pleistocene period. Their configuration seems to show that this karst system is pre-quaternary.

Evidence of a Marine Larval Stage in Endemic Hawaiian Stream Gobies from Isolated High-Elevation Locations

Tropical streams on high oceanic islands are characterized by populations of amphidromous gobioid fishes. Adult fish live and breed in freshwater and many spawn at high (>300 m) elevations. Newly hatched fry are swept down to the sea where they develop for a period of time before recruiting to a stream. In analogous habitats in other geographic areas, amphidromous populations have further evolved into landlocked forms (i.e., populations that spend their entire life cycle in freshwater). We analyzed depositional patterns of trace elements in the otoliths of adult Lentipes concolor, an amphidromous goby endemic to Hawaii, to determine whether landlocked forms occurred. Otoliths were obtained from fish collected from the Hawaiian stream habitats most likely to harbor landlocked populations—upper elevations of interrupted streams and sections of streams above high waterfalls. A transition from a marine phase to freshwater existence was demonstrated as a decrease from high to low strontium : calcium ratios in the otolith with increasing distance from the otolithˈs core. In every case, otoliths from these gobies showed evidence of a marine planktonic larval stage, suggesting that even in habitats physically isolated from the sea, these freshwater fish require a marine larval phase.