Artículos de revistas sobre el tema "Low-energy rivers"
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1
Menting, Foeke y Erik W. Meijles. "Local Factors Determining Spatially Heterogeneous Channel Migration in a Low-Energy Stream". Water 11, n.º 10 (16 de octubre de 2019): 2149. http://dx.doi.org/10.3390/w11102149.
Resumen
Since the 1990s, nature and water management policies have attempted to re-create natural rivers systems by mimicking curvy meandering planforms, based on the assumption that meandering is the natural channel-forming process. However, in low-energy river systems, the extent to which meandering plays a natural role is often minimal. This study aims to quantify contemporary lateral migration in the low-energy irregular sinuous lowland river system of the Drentsche Aa, The Netherlands, and to determine the factors influencing lateral channel migration in a heterogeneous valley fill. Although the river is classified as laterally immobile based on an empirical stability diagram, field observations prove that erosion and deposition are currently occurring. By analyzing historical and present-day maps, it was shown that lateral migration was highly spatially variable for the period 1924–2005. Sinuosity and valley gradient are not correlated to lateral migration rates, suggesting they are not a measure of lateral migration in the case study area, which is in line with the literature. Based on geomorphological and soil map analyses, it was shown that lateral migration rates are significantly higher in valley fills of aeolian sands than in clastic alluvial deposits, which on their turn are significantly higher than in peaty environments. Therefore, local conditions appear to be dominant over other factors such as stream power and bed grain size. These findings are important for river rehabilitation of low-energy rivers, because it shows that local valley fill conditions can greatly influence active lateral migration in the river.
2
Lakeh, Reza Baghaei, Christopher Salerno, Ega P. Herlim, Joseph Kiriakos y Saied Delagah. "Repurposing Reverse Osmosis Concentrate as a Low-Cost Thermal Energy Storage Medium". Journal of Clean Energy Technologies 8, n.º 4 (octubre de 2020): 31–40. http://dx.doi.org/10.18178/jocet.2020.8.4.522.
Resumen
The reject of the reverse osmosis water treatment process (aka brine, concentrate, ROC) is a mixture of salts that are dissolved in high salinity water. The ROC is classified as an industrial waste by the U.S. Environmental Protection Agency and can face regulatory limitations on disposal. State-of-the-art of ROC disposal includes deep-well injection, surface discharge to rivers, discharge to the ocean, and evaporation ponds. In this study, the feasibility of using Reverse Osmosis Concentrate as a low-cost Thermal Energy Storage (TES) medium is explored by a techno-economic analysis. The normalized cost of TES (cost per unit volume of stored thermal energy) is estimated through a series of cost analyses and is compared to the cost targets of the U.S. Department of Energy for low-cost thermal energy storage. It was shown that the normalized cost of TES using ROC salt content is in the range of $6.11 to $8.73 depending on ROC processing methods.
3
Candel, Jasper H. J., Bart Makaske, Niels Kijm, Maarten G. Kleinhans, Joep E. A. Storms y Jakob Wallinga. "Self‐constraining of low‐energy rivers explains low channel mobility and tortuous planforms". Depositional Record 6, n.º 3 (19 de mayo de 2020): 648–69. http://dx.doi.org/10.1002/dep2.112.
4
Yuskar, Yuniarti y Tiggi Choanji. "Uniqueness Deposit of Sediment on Floodplain Resulting From Lateral Accretion on Tropical Area". Journal of Geoscience, Engineering, Environment, and Technology 2, n.º 1 (1 de marzo de 2017): 14. http://dx.doi.org/10.24273/jgeet.2017.2.1.12.
Resumen
Kampar rivers has a length of 413 km with average depth of 7.7 m and width of 143 m. Sixty percent of this rivers are meandering fluvial system which transport and deposit a mixture of suspended and bed-load (mixed load) along low energy. River channel that moving sideways by erosion is undergoing lateral migration and the top of the point bar becomes the edge of the floodplain and the fining-upward succession of the point bar will be capped by overbank deposits of Kampar River. Along the Kampar Rivers, there are more than 60% of floodplain sediments and almost all of the floodplain formed by bend migration on the suspended-load channels of Kampar watershed. This formation consist of succession of fine to medium sand and silt/mud, with root traces, that form as drapes on the prograding bank. These beds dip mostly channel wards and quickly wedge out as they grade up and onto the floodplain. The depositional model is presented showing how lateral accretion can make a significant contribution to the preservation of fine-grained within channel deposits in contemporary floodplains. The examples presented here demonstrate that analogues to ancient point-bar deposits containing alternating sandstone and shale sequences are common in the low-energy fluvial environments of Riau rivers especially Kampar rivers.
5
Restrepo, Juan Camilo, Aldemar Higgins, Jaime Escobar, Silvio Ospino y Natalia Hoyos. "Contribution of low-frequency climatic–oceanic oscillations to streamflow variability in small, coastal rivers of the Sierra Nevada de Santa Marta (Colombia)". Hydrology and Earth System Sciences 23, n.º 5 (16 de mayo de 2019): 2379–400. http://dx.doi.org/10.5194/hess-23-2379-2019.
Resumen
Abstract. This study evaluated the influence of low-frequency oscillations, that are linked to large-scale oceanographic–atmospheric processes, on streamflow variability in small tropical coastal mountain rivers of the Sierra Nevada de Santa Marta, Colombia. We used data from six rivers that had > 32 years of complete, continuous monthly streamflow records. This investigation employed spectral analyses to (1) explore temporal characteristics of streamflow variability, (2) estimate the net contribution to the energy spectrum of low-frequency oscillations to streamflow anomalies, and (3) analyze the linkages between streamflow anomalies and large-scale, low-frequency oceanographic–atmospheric processes. Wavelet analyses indicate that the 8–12-year component exhibited a quasi-stationary state, with a peak of maximum power between 1985 and 2005. These oscillations were nearly in phase in all rivers. Maximum power peaks occurred for the Palomino and Rancheria rivers in 1985 and 1995, respectively. The wavelet spectrum highlights a change in river variability patterns between 1995 and 2015, characterized by a shift towards the low-frequency oscillations' domain (8–12 years). The net contribution of these oscillations to the energy spectrum was as high as 51 %, a value much larger than previously thought for rivers in northwestern South America. The simultaneous occurrence of hydrologic oscillations, as well as the increase in the amplitude of the 8–12-year band, defined periods of extremely anomalous wet seasons during 1989–1990, 1998–2002 and 2010–2011, reflecting the role of low-frequency oscillations in modulating streamflow variability in these rivers. Cross-wavelet transform and wavelet coherence revealed high common powers and significant coherences in low-frequency bands (>96 months) between streamflow anomalies and Atlantic Meridional Oscillation (AMO), Pacific Decadal Oscillation (PDO) and the Tropical North Atlantic Index (TNA). These results show the role of large-scale, low-frequency oceanographic–climate processes in modulating the long-term hydrological variability of these rivers.
6
Naidu, L. D., S. Saravanan, M. Chidambaram, Mukesh Goel, Ashutosh Das y J. Sarat Chandra Babu. "Nanofiltration in Transforming Surface Water into Healthy Water: Comparison with Reverse Osmosis". Journal of Chemistry 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/326869.
Resumen
The natural surface water, especially available through rivers, is the main source of healthy water for the living beings throughout the world from ancient days as it consists of all essential minerals. With the advent of industrialization, gradually even the most prominent rivers have been polluted in all parts of the world. Although there are lots of technologies, nanofiltration (NF) has been chosen to transform river water into healthy water due to its unique advantages of retaining optimum TDS (with essential minerals required for human body), consuming of lower energy, and no usage of any chemicals. The prominent parameters of surface water and macro/microminerals of treated water have been analyzed. It is shown that NF is better in producing healthy water with high flux by consuming low energy.
7
Sheikh, Shakil Rehman, Syed Hassan Raza Shah, Umar Rauf, Fawad Rauf, Zareena Kausar, Umair Aziz, Muhammad Faizan Shah, Haseeb Yaqoob y Muhammad Bilal Khan Niazi. "A Low-Cost Sustainable Energy Solution for Pristine Mountain Areas of Developing Countries". Energies 14, n.º 11 (28 de mayo de 2021): 3160. http://dx.doi.org/10.3390/en14113160.
Resumen
The rise in energy requirements and its shortfall in developing countries have affected socioeconomic life. Communities in remote mountainous regions in Asia are among the most affected by energy deprivation. This study presents the feasibility of an alternate strategy of supplying clean energy to the areas consisting of pristine mountains and forest terrain. Southeast Asia has a much-diversified landscape and varied natural resources, including abundant water resources. The current study is motivated by this abundant supply of streams which provides an excellent environment for run-of-river micro vertical axis water turbines. However, to limit the scope of the study, the rivers and streams flowing in northern areas of Pakistan are taken as the reference. The study proposes a comprehensive answer for supplying low-cost sustainable energy solutions for such remote communities. The suggested solution consists of a preliminary hydrodynamic design using Qblade, further analysis using numerical simulations, and finally, experimental testing in a real-world environment. The results of this study show that the use of microturbines is a very feasible option considering that the power generation density of the microturbine comes out to be approximately 2100 kWh/year/m2, with minimal adverse effects on the environment.
8
Lohani, Sunil Prasad y Andrew Blakers. "100% renewable energy with pumped-hydro-energy storage in Nepal". Clean Energy 5, n.º 2 (13 de mayo de 2021): 243–53. http://dx.doi.org/10.1093/ce/zkab011.
Resumen
Abstract A radical transformation of the global energy system is underway. Solar photovoltaics and wind now comprise three-quarters of the global net new electricity-generation-capacity additions because they are cheap. The deep renewable electrification of energy services including transport, heating and industry will allow solar and wind to largely eliminate fossil fuels over the next few decades. This paper demonstrates that Nepal will be able to achieve energy self-sufficiency during the twenty-first century. Nepal has good solar and moderate hydroelectric potential but has negligible wind- and fossil-energy resources. The solar potential is about 100 times larger than that required to support a 100% solar-energy system in which all Nepalese citizens enjoy a similar per-person energy consumption to developed countries, without the use of fossil fuels and without the environmental degradation resulting from damming Nepal’s Himalayan rivers. Nepal has vast low-cost off-river pumped hydro-energy-storage potential, thus eliminating the need for on-river hydro storage and moderating the need for large-scale batteries. Solar, with support from hydro and battery storage, is likely to be the primary route for renewable electrification and rapid growth of the Nepalese energy system.
9
Candel, Jasper H. J., Maarten G. Kleinhans, Bart Makaske, Wim Z. Hoek, Cindy Quik y Jakob Wallinga. "Late Holocene channel pattern change from laterally stable to meandering – a palaeohydrological reconstruction". Earth Surface Dynamics 6, n.º 3 (31 de agosto de 2018): 723–41. http://dx.doi.org/10.5194/esurf-6-723-2018.
Resumen
Abstract. River channel patterns may alter due to changes in hydrological regime related to changes in climate and/or land cover. Such changes are well documented for transitions between meandering and braiding rivers, whereas channel pattern changes between laterally stable and meandering rivers are poorly documented and understood. We hypothesize that many low-energy meandering rivers had relatively low peak discharges and were laterally stable during most of the Holocene, when climate was relatively stable and human impact was limited. Our objectives in this work are to identify a Late Holocene channel pattern change for the low-energy Overijsselse Vecht river, to develop and apply a novel methodology to reconstruct discharge as a function of time following a stochastic approach, and to relate this channel pattern change to reconstructed hydrological changes. We established that the Overijsselse Vecht was laterally virtually stable throughout the Holocene until the Late Middle Ages, after which large meanders formed at lateral migration rates of about 2 m yr−1. The lateral stability before the Late Middle Ages was constrained using a combination of coring information, ground-penetrating radar (GPR), radiocarbon (14C) dating, and optically stimulated luminescence (OSL) dating. We quantified bankfull palaeodischarge as a function of time based on channel dimensions that were reconstructed from the scroll bar sequence and channel cut-offs using coring information and GPR data, combined with chronological constraints from historical maps and OSL dating. We found that the bankfull discharge was significantly greater during the meandering phase compared to the laterally stable phase. Empirical channel and bar pattern models showed that this increase can explain the channel pattern change. The bankfull discharge increase likely reflects climate changes related to the Little Ice Age and/or land use changes in the catchment, in particular as a result of peat reclamation and exploitation.
10
Penczak, T., A. A. Agostinho, N. S. Hahn, R. Fugi y L. C. Gomes. "Energy budgets of fish populations in two tributaries of the Paraná River, Paraná, Brazil". Journal of Tropical Ecology 15, n.º 2 (marzo de 1999): 159–77. http://dx.doi.org/10.1017/s0266467499000735.
Resumen
The energy budget of all fish populations was estimated in two small tributaries of the Paraná River (Paraná, Brazil). Total energy consumed by fish in the Caracu and the Agua do Rancho Rivers was 4.1 and 1.8 MJ m−2 y−1, and food items consumed were 2284 and 994.5 g wet weight m−2 y−1, respectively. The gross (K1) and net (K2) ecological efficiency coefficients were very low, but 43.2 and 59.6% of the total fish diet in these two streams, respectively, consisted of plant detritus. In both fish communities, omnivorous (opportunist) species dominated and specialists were rare. Although the Caracu River was more affected by human activity than was the Agua do Rancho, ecological efficiency coefficients calculated for the dominant fish populations were not significantly different.
11
Bril, A. A., P. F. Vasko y A. V. Moroz. "EXPRESS ASSESSMENT OF HYDROPOWER POTENTIAL OF THE SMALL RIVERS IN UKRAINE WITH ACCOUNT OF ENVIRONMENTAL RESTRICTIONS". Alternative Energy and Ecology (ISJAEE), n.º 25-30 (7 de diciembre de 2018): 86–95. http://dx.doi.org/10.15518/isjaee.2018.25-30.086-095.
Resumen
The article is devoted to the development of an express method for assessing the potential of hydropower resources of the small rivers in Ukraine, taking into account the requirements of the current regulatory framework in the environmental and energy sectors, which provides objective information for the development of small hydropower stations at the current stage of alternative energy development. The article determines the environmental restrictions of small hydropower based on the provisions of the current regulatory and legal framework of Ukraine, the criteria for the ecological value of the territory and the principles of preserving the diversity of wild fauna of rivers. Restrictions on the use of water for the production of small hydropower plants take into account the sanitary discharge, the continuous operation of fishers, low water, floods, operational measures to regulate the water flow through hydroconstructions, the regulation of hydroelectric power through the watercourse which allows practically no distortion of the natural hydrological regime and biological state of river below the station. Restrictions on the use of the territory for the construction of small hydropower stations take into account the presence of national natural parks, reserves, and natural monuments, places of deposits of minerals and mineral waters, historical and cultural heritage, special purpose land. Restrictions on the permissible bias of river sections have been introduced with regard to environmental restrictions. The article substantiates the significance of the technical potential of the hydropower resources of small rivers in Ukraine, taking into account environmental restrictions, at the level of 1270 million kWh/year (about 375 MW of installed capacity of small HPPs), and its distribution over the hydrological zones of the country. It is established that the volume of technically achievable potential of hydropower resources, even for the main deep-water small rivers of Ukraine, is within 3–15% of their natural potential. The results obtained are essential for the development of a modern concept of regional programs for the development of small hydropower and the Energy Strategy, implementation of the activities of the National Action Plan for Renewable Energy in Ukraine.
12
Barca, Sandra, Rufino Vieira-Lanero, David José Nachón, Javier Sánchez-Hernández, María del Carmen Cobo y Fernando Cobo. "Complexity of the Relationship between Environmental Factors, Interspecific Competition, and Intrinsic Traits of the Species in Explaining the Invasive Success of Gobio lozanoi Doadrio & Madeira, 2004". Water 13, n.º 21 (1 de noviembre de 2021): 3043. http://dx.doi.org/10.3390/w13213043.
Resumen
The increase of non-native species in rivers is of great concern. To assess the potential impact of a species it is necessary to consider the ecological state of the receiving ecosystem and the biology of the potentially invasive species. In this work we characterize two populations of Gobio lozanoi Doadrio & Madeira, 2004 (bio-metric and demographic parameter) and the invasibility (as a function of habitat quality, competing species, food supply, etc.) of the two rivers that they inhabit. In addition, biomarkers of energy reserve level are analyzed to investigate their role in the invasiveness of the species. The results show differences in energy reserve levels and invasiveness between the two fish populations, and differences in the potential invasibility of the two tributaries. In the river with lower resistance to invasion, the G. lozanoi population is well-structured, and specimens have higher lipid values. On the contrary, in the river with better ecological status (and therefore greater resistance to invasion) we found lower lipid values, higher protein values and low juvenile survival rate. The lipid level is revealed as a good indicator of invasiveness in populations of alien species, under favorable conditions for invasion.
13
Amat-Trigo, Fátima, Mar Torralva, Daniel González-Silvera, Francisco Javier Martínez-López y Francisco José Oliva-Paterna. "Plasticity in Reproductive Traits, Condition and Energy Allocation of the Non-Native Pyrenean Gudgeon Gobio lozanoi in a Highly Regulated Mediterranean River Basin". Water 13, n.º 3 (2 de febrero de 2021): 387. http://dx.doi.org/10.3390/w13030387.
Resumen
The invasion success of non-native fish, such as Pyrenean gudgeon Gobio lozanoi in several Iberian rivers, is often explained by the expression of its life history traits. This study provides the first insights into the reproductive traits, fish condition, and energy allocation (protein and lipid contents of tissues) of this species, along a longitudinal gradient in one of the most regulated river basins in the Iberian Peninsula, the Segura river. Larger sizes of first maturity, higher fecundity and larger oocytes were found in fluvial sectors with the most natural flow regimes, characterised by a low base flow with high flow peaks in spring and autumn. A delay in the reproductive period, lower fish condition and no differences in sex-ratio were observed in fluvial sectors with a high increase in base flow and notable inversion in the seasonal pattern of flow regime. Lipid contents in the liver and gonads were stable during the reproductive cycle and decreases in muscle were noted, whereas ovarian and liver proteins increased. In relation to energy allocation for G. lozanoi, an intermediate energy strategy was observed between income and capital breeding. Our results support the hypothesis that the high plasticity of G. lozanoi population traits plays a significant role in its success in a highly regulated Mediterranean river basin. Understanding the mechanisms by which flow regulation shapes fish populations in Mediterranean type-rivers could inform management actions.
14
Šarauskienė, Diana, Gintaras Adžgauskas, Jūratė Kriaučiūnienė y Darius Jakimavičius. "Analysis of Hydrologic Regime Changes Caused by Small Hydropower Plants in Lowland Rivers". Water 13, n.º 14 (17 de julio de 2021): 1961. http://dx.doi.org/10.3390/w13141961.
Resumen
Hydropower remains the most important and largest source of renewable energy. However, besides many additional benefits, such as dams for water supply, irrigation, flood control, recreation, navigation, etc., hydropower generation has a negative impact on the environment. This study aimed to investigate the hydrologic changes in Lithuanian lowland rivers caused by small hydropower plants (HPPs). Thirty-two indicators of hydrologic alteration (IHA) were studied in 11 rivers downstream of hydropower plants in the post-impact and pre-impact periods. The findings showed that HPPs and reservoirs considerably disturbed the primary flow of river ecosystems downstream. The largest changes in mean IHA values were found for low and high pulse characteristics (up to 57%) and the number of reversals (up to 44%). Only small or no deviations of the timing of annual extreme flows were found. The number of reversals, a low pulse count, and a fall rate were the flow characteristics that fell outside their historical ranges of variability most often. Six (out of 11) hydropower plants were identified that provoked hydrologic alterations of a moderate degree.
15
Hapsari, Novy, Sri Yatmani, Herbert Rajagoekgoek, Ratnawati Ratnawati y Ulfatul Faiza. "STUDI RANCANGAN PEMBANGKIT LISTRIK TENAGA MIKROHIDRO (PLTMH) PADA ALIRAN SUNGAI CISADANE DI KELURAHAN KERANGGAN". Empowerment in the Community 1, n.º 1 (31 de enero de 2020): 27. http://dx.doi.org/10.31543/ecj.v1i1.359.
Resumen
The need for electricity has increased every year. One of the most popular supply of electrical energy is electrical energy from energy sources flowing and plunging water, called as the Micro Hydro Power Plant (PLTMH). Cisadane River is one of the major rivers with length around 80 kilometers and crosses 44 districts in 5 regencies / cities, including desa Kranggan, South Tangerang. Therefore, community service is carried out in an effort to utilize and optimize the flow of the Cisadane river. The Study of PLTMH design for community service program was conducted. Data of river flow, altitude and location of the river flow will be collected so that it can be calculated and observed for the design of PLTMH that best suits the efficiency of the largest electrical energy, which is obtained using the TurbinPro software program. PLTMH planning chose to use a propeller/kaplan turbine because of its low head which is 4 meters. The power generated is 994 kW at a maximum head with an efficiency of 91.2% and a river flow of 52.26 m3/s and at a minimum head of 601 kW with an efficiency of 82.2% and a discharge of 47.56 m3/s. Keywords: electrical energy, community service program, PLTMH, power generation, Kaplan turbine
16
Prasad, Nadipuram R., Satish J. Ranade y Phuc Huu Nguyen. "Low-head hydropower energy resource harvesting: design and manufacturing of the (HyPER) harvester". Science and Technology Development Journal 18, n.º 3 (30 de agosto de 2015): 132–42. http://dx.doi.org/10.32508/stdj.v18i3.894.
Resumen
The design and manufacturing of a revolutionary hydropower harvester with characteristics that embrace the ecology and the environment is described. Guided by NEPA standards for environmental protection, the design concept incorporates a modular and self-supporting structure with a vertical-axis turbine-generator system that is: a) fabricated using Fiberglass and Carboncomposites and is light weight, and b) is easy to manufacture and assemble utilizing offthe- shelf electromechanical components and deploy to produce the desired power. A computational fluid dynamics (CFD) software, ANSYS®, is used to optimize the flow characteristics of the harvester. A fullyscalable, modular and easily deployable hydropower generating system prototype of a 10kW low-head hydropower harvester with 4- blade fixed-pitch impeller is presented. The technology is adaptable for low-head drops along irrigation canals with existing structures and as modular weirs across small rivers and streams worldwide.
17
Setyawan, E. Y., S. Djiwo, D. H. Praswanto, P. Suwandono y P. Siagian. "Design of Low Flow Undershot Type Water Turbine". JOURNAL OF SCIENCE AND APPLIED ENGINEERING 2, n.º 2 (28 de noviembre de 2019): 50. http://dx.doi.org/10.31328/jsae.v2i2.1184.
Resumen
Many water sources around us which have kinetic energy to run waterwheels are not optimally utilized. This energy can be converted into an energy source that can produce electricity. Therefore this study produced a design of a waterwheel that could be used in low-flow rivers to produce electricity by adding generators. Waterwheel modeling using Ansys is calculated based on flow assumptions. Modeling using this system provides advantages in the form of computational power efficiency, the stability of numerical calculations and the accuracy of the resulting solutions. Numerical analysis of the waterwheel is assumed that the waterwheel is half floating on the surface of the water. As stated in the limitation of the problem that the incoming water flowing at a speed of 5 m/s from the flow moves the wheel. The flow rate of water that hit the blade on the waterwheel causes the waterwheel to rotate which is pressured by the flow of water with a number of 12 blades. With a relatively simple design, the waterwheel produces a wheel rotation I of 91 Rpm and II of 78 Rpm, with a torque of 39.2 N by using some analysis of this design can be applied to river flow with low flow velocity. The relatively simple design makes it easy to be produced and maintenance. River flow used is in the Malang District with a flow velocity of 1 m/s gets a power of 1128 W on waterwheel I while on waterwheel II gets a power of 967 W.
18
de Araújo, Kleiton R., Henrique O. Sawakuchi, Dailson J. Bertassoli Jr., André O. Sawakuchi, Karina D. da Silva, Thiago B. Vieira, Nicholas D. Ward y Tatiana S. Pereira. "Carbon dioxide (CO<sub>2</sub>) concentrations and emission in the newly constructed Belo Monte hydropower complex in the Xingu River, Amazonia". Biogeosciences 16, n.º 18 (18 de septiembre de 2019): 3527–42. http://dx.doi.org/10.5194/bg-16-3527-2019.
Resumen
Abstract. The Belo Monte hydropower complex located in the Xingu River is the largest run-of-the-river (ROR) hydroelectric system in the world and has one of the highest energy production capacities among dams. Its construction received significant media attention due to its potential social and environmental impacts. It is composed of two ROR reservoirs: the Xingu Reservoir (XR) in the Xingu's main branch and the Intermediate Reservoir (IR), an artificial reservoir fed by waters diverted from the Xingu River with longer water residence time compared to XR. We aimed to evaluate spatiotemporal variations in CO2 partial pressure (pCO2) and CO2 fluxes (FCO2) during the first 2 years after the Xingu River impoundment under the hypothesis that each reservoir has contrasting FCO2 and pCO2 as vegetation clearing reduces flooded area emissions. Time of the year had a significant influence on pCO2 with the highest average values observed during the high-water season. Spatial heterogeneity throughout the entire study area was observed for pCO2 during both low- and high-water seasons. FCO2, on the other hand, only showed significant spatial heterogeneity during the high-water period. FCO2 (0.90±0.47 and 1.08±0.62 µmol m2 d−1 for XR and IR, respectively) and pCO2 (1647±698 and 1676±323 µatm for XR and IR, respectively) measured during the high-water season were on the same order of magnitude as previous observations in other Amazonian clearwater rivers unaffected by impoundment during the same season. In contrast, during the low-water season FCO2 (0.69±0.28 and 7.32±4.07 µmol m2 d−1 for XR and IR, respectively) and pCO2 (839±646 and 1797±354 µatm for XR and IR, respectively) in IR were an order of magnitude higher than literature FCO2 observations in clearwater rivers with naturally flowing waters. When CO2 emissions are compared between reservoirs, IR emissions were 90 % higher than values from the XR during low-water season, reinforcing the clear influence of reservoir characteristics on CO2 emissions. Based on our observations in the Belo Monte hydropower complex, CO2 emissions from ROR reservoirs to the atmosphere are in the range of natural Amazonian rivers. However, the associated reservoir (IR) may exceed natural river emission rates due to the preimpounding vegetation influence. Since many reservoirs are still planned to be constructed in the Amazon and throughout the world, it is critical to evaluate the implications of reservoir traits on FCO2 over their entire life cycle in order to improve estimates of CO2 emissions per kilowatt for hydropower projects planned for tropical rivers.
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Malika Ikramova, Khairullo Kabilov, Alisher Khodjiev, Ifoda Akhmedkhodjaeva y Dilshod Nazaraliev. "IMPROVEMENT OF WATER ALLOCATION EFFICIENCY IN THE AMU-SURKHAN RIVERS BASIN". World Science 1, n.º 8(48) (31 de agosto de 2019): 4–7. http://dx.doi.org/10.31435/rsglobal_ws/31082019/6623.
Resumen
In the article efficiency of water distribution in the territory of Amu-Surkon basin is analysed and based on the results, provided the recommendations. The study is conducted within the project QH-A-QH-2018-409 “Increase efficiency of water resources management in Surkhandarya region: improve interbasin re-distribution of the water resources of Surkhandarya and Sherabaddarya Rivers” funded by Uzbekistan government. The main problems of water management in the Surkhandarya region are: outdated irrigation systems requiring an urgent modernization; large dependence on pump irrigation; low energy efficiency of pumping stations due to use of the old high energy-consuming equipment; irrational distribution and large unproductive technical and operational water losses. Increase of sensitivity to climate change with forecasting of 50% water deficit by 2050 leads to drought and further desertification, including impact on food security. In the article some results are introduced related to improve water allocation by redistribution of water resources between the river basins in the region aimed to reduce of pumped water use for irrigation.
20
Tzoraki, Ourania. "Operating Small Hydropower Plants in Greece under Intermittent Flow Uncertainty: The Case of Tsiknias River (Lesvos)". Challenges 11, n.º 2 (3 de agosto de 2020): 17. http://dx.doi.org/10.3390/challe11020017.
Resumen
In arid and semi-arid parts of the world, river exploitation is intensive, involving water storage for irrigation or hydropower generation. In Greece, 100 small hydropower plants (SHPs) take advantage of less than 10% of the hydropower potential of low flow streams (<2 m3/s), a very small amount in relation to the 70% of the European Union. The energy policy of complete decarbonization of the country by 2023 on a national scale opens the road for new investments in SHP projects, especially in intermittent-flow streams of the Greek islands. Simulated flows by the Modello Idrologico SemiDistribuito in continuo (MISDc model) are used to construct the annual flow duration curve (FDC) to study and assess the hydropower potential of an intermittent stream (Tsiknias river, Lesvos, Greece). For Tsiknias River, but also for six other intermittent-flow rivers of Crete island, the capacity factor (CF), which represents the mean annual power of the hydropower plant, should remain >75% to exploit the river’s potential. The FDC and CF are essential in designing SHP projects in intermittent-flow streams with long no-flow periods. The development of public participatory approaches and a closer cooperation among policy makers and stakeholders should work to promote hydropower exploitation and accelerate licensing procedures.
21
BAKSHTANIN, A. M., A. P. KRYLOV y E. S. BEGLYAROVA. "THE INVESTMENT ATTRACTIVENESS OF TIDAL ENERGY AND THE FACTORS THAT DETERMINE ITS DEVELOPMENT IN THE WORLD". Prirodoobustrojstvo, n.º 2 (2021): 50–57. http://dx.doi.org/10.26897/1997-6011-2021-2-50-57.
Resumen
Due to the increasing demand of energy consumers for high-quality, energy-intensive sources of electricity generation with a high EROI index, the implementation of tidal power plant projects is becoming increasingly attractive. At the moment, there are more than 100 stations in the world where the technical realization of TPP projects is possible. Until recently, cheap and seemingly limitless fossil energy allowed most of society to ignore the importance of the contribution of alternative sources of energy generation such as PES, but now their demand is increasing. The implementation of TPP construction projects contributes to the sustainable development of coastal towns and makes a signifi cant contribution to the energy balance of the system. The energy potential of tidal energy is quite large and comparable to the energy potential of the rivers of the Globe. Compared to river energy, the energy of tides and wind waves is low-potential, and therefore in most cases more expensive. It is worth noting that the advantage of tidal energy is environmental cleanliness, reducing the likelihood of fl ooding of adjacent territories and the absence of changes in the coastal landscape.
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Kazem, Masoud, Hossein Afzalimehr, Mohammad Nazari-Sharabian y Moses Karakouzian. "Determination of Skin Friction Factor in Gravel Bed Rivers: Considering the Effect of Large-Scale Topographic Forms in Non-Uniform Flows". Hydrology 9, n.º 4 (31 de marzo de 2022): 58. http://dx.doi.org/10.3390/hydrology9040058.
Resumen
Determination of skin friction factor has been a controversial topic, particularly in gravel-bed rivers where total flow resistance is influenced by the existence of small-scale skin roughness and large-scale topographic forms. The accuracy of existing models predicting skin friction factors in conditions where small-scale skin roughness and large-scale topographic forms exist is very low. The objective of this study is to develop a modified model that improves the accuracy of the determination of skin friction factors in gravel-bed rivers. To this end, 100 velocity profile data obtained from eight gravel-bed rivers were utilized to develop an analytical method that considers the momentum thickness of the boundary layer and its deviation in large-scale topographic bedforms in a 1D force-balance model. The results show that the accuracy of the skin friction factors is enhanced when (1) the model is in the form of an exponential function of energy slope, and (2) the deviation of momentum thickness is considered in the model. The proposed model results in high accuracy of the predicted skin friction factors for energy slopes between 0.001 and 0.1, which exist in most gravel-bed rivers with different morphologies. Additionally, this study model was used to modify the classic Einstein–Strickler equation. The modified equation resulted in improved accuracy of the predicted skin friction factors in non-uniform flow conditions even when velocity profiles and energy slope were not available.
23
Qu, Xiang Rong. "The Present Situation of Water Pollution in Shenyang City and Control Measures". Advanced Materials Research 281 (julio de 2011): 301–4. http://dx.doi.org/10.4028/www.scientific.net/amr.281.301.
Resumen
Facing the present situation of water quality in Shenyang city, combining with the setting up national eco-city, the main measures of water pollution control should include the readjusting industry structure; developing high-technology industries with low energy, low water consumption, high efficiency and no-pollution; controlling pollution sources; constructing municipal wastewater treatment plants; reusing the treated water as well as comprehensive renovation of polluted rivers and so on.
24
Liu, Huaixiang, Zhaoyin Wang y Yongjun Lu. "Self-adjustment mechanism of bed structures under hydrology and sediment regimes". Hydrology Research 47, S1 (3 de agosto de 2016): 136–48. http://dx.doi.org/10.2166/nh.2016.008.
Resumen
Bed structures develop in many coarse gravel-bed rivers, and the distribution of bed structures is obviously impacted by the environment conditions, especially hydrology and sediment regimes. This study carried out field investigations in natural tributaries of the Yangtze River to study the sizes of bed structures, their distribution in the basin, as well as their connections with local hydrology and sediment regimes. A field experiment was also conducted to study the evolution and functions of bed structures. Results of both the investigations and experiment indicated that under the conditions of low bedload, the structure intensity is in a positive correlation with the unit-width stream power, which is consumed by bed structures when the river is in a dynamic equilibrium. If the structures are not able to dissipate the whole energy, the river status turns into disequilibrium and the riverbed would be eroded by excess energy, and the river system would move to a stable position on the structure-power equilibrium line. The fluvial morphology of coarse-grained riverbeds is controlled by this mechanism to some extent. Sometimes excess energy can be consumed by bedload transport even with insufficient structure intensity, thus a unified power consumption model including bedload is also discussed.
25
Wu, Xiu-hua. "Low-Intensity and Micropore Pipes Aeration Powered by Wind-Solar Energy in Treating Urban Black-Odour Rivers". IOP Conference Series: Earth and Environmental Science 189 (6 de noviembre de 2018): 052064. http://dx.doi.org/10.1088/1755-1315/189/5/052064.
26
Huang, Haocai, Gang Wu, Chaowu Sheng, Jiannan Wu, Danhua Li y Hangzhou Wang. "Improved Cyanobacteria Removal from Harmful Algae Blooms by Two-Cycle, Low-Frequency, Low-Density, and Short-Duration Ultrasonic Radiation". Water 12, n.º 9 (29 de agosto de 2020): 2431. http://dx.doi.org/10.3390/w12092431.
Resumen
Harmful algae blooms (HAB) in eutrophic lakes and rivers have become serious water quality problems that are difficult to eliminate using common methods. Previous research has demonstrated that powerful ultrasound can somewhat control cyanobacteria in HABs; however, effective and energy-efficient settings for ultrasonic parameters have not yet been rigorously determined. The results of this study showed that the effect of cyanobacteria removal was enhanced with ultrasonic frequencies, densities, and radiation durations of 20–90 kHz, 0.0005–0.1 W/mL and 0.5–10 min, respectively. Our analyses further demonstrated that the effective distance of ultrasound decreased with increasing frequency, and that damaged algae cells were able to repair themselves at low ultrasonic densities. To address the high energy consumption and small effective distance of conventional ultrasonic radiation treatments, we proposed a new cyanobacteria removal method based on two applications of low-frequency, low-density and short-duration ultrasonic radiation. We defined the energy effectiveness factors of ultrasonic radiation for algae removal as the algae removal rate divided by ultrasonic dosage. This method yielded an 87.6% cyanobacteria removal and the highest energy effectiveness factor, suggesting that two cycles of treatment provide a low-energy method for enhancing existing algae-removing technologies used in large bodies of water.
27
BEKKIEV, Mukhtar Yu y Rizuan O. KALOV. "Revisiting the hydropower assessment of the economically effective part of the river flow of Kabardino-Balkaria". Regional Economics: Theory and Practice 20, n.º 1 (17 de enero de 2022): 186–200. http://dx.doi.org/10.24891/re.20.1.186.
Resumen
Subject. This article deals with the issues related to the economic potential of hydropower engineering. Objectives. The article aims to define the boundaries of the economically justified growth in the production of own electric energy, taking into account the high variability of the natural discharge regime of the mountain zone. Methods. For the study, we used mathematical and analytical methods, and the method of natural analogues. Results. Based on the analysis of the impact of the transformation of mountain landscapes on channel processes, the article determines the economically efficient part of the river flow with the highest possible accuracy, designates the most favorable control sections of watercourses, and proposes energy-technological schemes for the implementation of their properties. Conclusions. The low economic efficiency of hydroelectric power plants’ operation in mountainous regions is due to an abnormally growing discrepancy between the phases of climate variability and the correlated water rate in the control points of rivers. Linking several hydroelectric power plants with the optimal interaction mode will increase the economic efficiency of energy output and reduce energy loss.
28
Paiva, R. C. D., W. Collischonn, M. P. Bonnet y L. G. G. de Gonçalves. "On the sources of hydrological prediction uncertainty in the Amazon". Hydrology and Earth System Sciences 16, n.º 9 (5 de septiembre de 2012): 3127–37. http://dx.doi.org/10.5194/hess-16-3127-2012.
Resumen
Abstract. Recent extreme events in the Amazon River basin and the vulnerability of local population motivate the development of hydrological forecast systems using process based models for this region. In this direction, the knowledge of the source of errors in hydrological forecast systems may guide the choice on improving model structure, model forcings or developing data assimilation systems for estimation of initial model states. We evaluate the relative importance of hydrologic initial conditions and model meteorological forcings errors (precipitation) as sources of stream flow forecast uncertainty in the Amazon River basin. We used a hindcast approach that compares Ensemble Streamflow Prediction (ESP) and a reverse Ensemble Streamflow Prediction (reverse-ESP). Simulations were performed using the physically-based and distributed hydrological model MGB-IPH, comprising surface energy and water balance, soil water, river and floodplain hydrodynamics processes. The model was forced using TRMM 3B42 precipitation estimates. Results show that uncertainty on initial conditions plays an important role for discharge predictability, even for large lead times (∼1 to 3 months) on main Amazonian Rivers. Initial conditions of surface waters state variables are the major source of hydrological forecast uncertainty, mainly in rivers with low slope and large floodplains. Initial conditions of groundwater state variables are important, mostly during low flow period and in the southeast part of the Amazon where lithology and the strong rainfall seasonality with a marked dry season may be the explaining factors. Analyses indicate that hydrological forecasts based on a hydrological model forced with historical meteorological data and optimal initial conditions may be feasible. Also, development of data assimilation methods is encouraged for this region.
29
Paiva, R. C. D., W. Collischonn, M. P. Bonnet y L. G. G. Gonçalves. "On the sources of hydrological prediction uncertainty in the Amazon". Hydrology and Earth System Sciences Discussions 9, n.º 3 (20 de marzo de 2012): 3739–60. http://dx.doi.org/10.5194/hessd-9-3739-2012.
Resumen
Abstract. Recent extreme events in the Amazon River basin and the vulnerability of local population motivate the development of hydrological forecast systems (HFSs) using process based models for this region. In this direction, the knowledge of the source of errors in HFSs may guide the choice on improving model structure, model forcings or developing data assimilation (DA) systems for estimation of initial model states. We evaluate the relative importance of hydrologic initial conditions (ICs) and model meteorological forcings (MFs) errors (precisely precipitation) as sources of stream flow forecast uncertainty in the Amazon River basin. We used a hindcast approach developed by Wood and Lettenmaier (2008) that contrasts Ensemble Streamflow Prediction (ESP) and a reverse Ensemble Streamflow Prediction (reverse-ESP). Simulations were performed using the physically-based and distributed hydrological model MGB-IPH, comprising surface energy and water balance, soil water, river and floodplain hydrodynamics processes. Model was forced using TRMM 3B42 precipitation estimates. Results show that uncertainty on initial conditions play an important role for discharge predictability even for large lead times (~1 to 3 months) on main Amazonian Rivers. ICs of surface waters state variables are the major source of hydrological forecast uncertainty, mainly in rivers with low slope and large floodplains. ICs of groundwater state variables are important mostly during low flow period and southeast part of the Amazon, where lithology and the strong rainfall seasonality with a marked dry season may be the explaining factors. Analyses indicate that hydrological forecasts based on a hydrological model forced with historical meteorological data and optimal initial conditions, may be feasible. Also, development of DA methods is encouraged for this region.
30
Lyatkher, V. M. "Orthogonal Turbine for Free Rivers and Channels". Alternative Energy and Ecology (ISJAEE), n.º 13-15 (26 de junio de 2019): 12–23. http://dx.doi.org/10.15518/isjaee.2019.13-15.12-23.
Resumen
The paper discusses the problem of using the energy of rivers without creating the dams and flooding vast areas and notes that there is a progress in the implementation and development of the ideas of patent in 1931 (the speed of the workers turbine blades is higher than flow rate). The paper gives the diagrams of the new turbines of this type, for example a balanced 6-tier single-blade turbine, turbine-spiral, a balanced twoblades turbine. Moreover, the paper deals with the features free-threaded orthogonal turbines in the streams of the limited width and depth. The most important characteristic of a turbine is the turbine's power factor that is equal to the ratio of the energy of the rotating turbine to the kinetic energy of the flow in the current tube passing through the turbine circuit. There is a possibility of a significant increase in the power of the turbine in comparison with the conditions of use unlimited streams. The increase in turbine power in a straitened flow is associated with an increase in the flow velocity in the turbine on the approach to the rear section of the blades’ track. It is set the requirements of the turbine parameters for maximum power at a given water flow and the permissible level rise in the river. These requirements relate to the certain rules for selecting the number of blades (and solidity) of the turbine, taking into account the permissible increasing in the water level (backup) in front of the turbine. The paper notes the turbines instability at low speed of rotation, describes a turbine design modification that eliminates this drawback. Modification of the high-speed orthogonal turbines is the use of accelerating blades with a cup-shaped cross-section, placed on the route within a diameter 2 times smaller than the diameter of the main (working) blades of the smoothly streamlined profile. It is concluded that all considered variants of turbines for streams with limited cross-section, the design of the blade system may be made rigid, which eliminates the single central shaft (axle), replacing it with a reference semi-shafts.
31
Jager, Henriette I., Rebecca A. Efroymson y Latha M. Baskaran. "Avoiding Conflicts between Future Freshwater Algae Production and Water Scarcity in the United States at the Energy-Water Nexus". Water 11, n.º 4 (20 de abril de 2019): 836. http://dx.doi.org/10.3390/w11040836.
Resumen
Sustainable production of algae will depend on understanding trade-offs at the energy-water nexus. Algal biofuels promise to improve the environmental sustainability profile of renewable energy along most dimensions. In this assessment of potential US freshwater production, we assumed sustainable production along the carbon dimension by simulating placement of open ponds away from high-carbon-stock lands (forest, grassland, and wetland) and near sources of waste CO 2 . Along the water dimension, we quantified trade-offs between water scarcity and production for an ‘upstream’ indicator (measuring minimum water supply) and a ‘downstream’ indicator (measuring impacts on rivers). For the upstream indicator, we developed a visualization tool to evaluate algae production for different thresholds for water surplus. We hypothesized that maintaining a minimum seasonal water surplus would also protect river habitat for aquatic biota. Our study confirmed that ensuring surplus water also reduced the duration of low-flow events, but only above a threshold. We also observed a trade-off between algal production and the duration of low-flow events in streams. These results can help to guide the choice of basin-specific sustainability targets to avoid conflicts with competing water users at this energy-water nexus. Where conflicts emerge, alternative water sources or enclosed photobioreactors may be needed for algae cultivation.
32
Singal, Sunil K., R. P. Saini y C. S. Raghuvanshi. "Effects of Soil Conditions on Cost of Low Head SHP Schemes". Hydro Nepal: Journal of Water, Energy and Environment 8 (16 de junio de 2011): 24–28. http://dx.doi.org/10.3126/hn.v8i0.4904.
Resumen
Energy is the engine of growth of any developing economy. Consumption of electrical energy is universally accepted indicator of progress in the agricultural, industrial and commercial sectors, as also of the well being of the people of the nation. India is blessed with many rivers, natural streams, canal networks and mountains offering tremendous small hydropower potential which is clean and technically proven source of energy. Under this study, an attempt has been made to discuss the cost sensitive parameters of small hydropower schemes. Based on the cost sensitive parameters, the methodology for estimation of cost of low head small hydropower scheme has been evolved and the effect of soil conditions on cost of SHP schemes discussed. DOI: http://dx.doi.org/10.3126/hn.v8i0.4904Hydro Nepal: Journal of Water, Energy and Environment Issue No. 8, 2011 JanuaryPage: 24-28Uploaded date: 16 June, 2011
33
Monti, Dominique y Pierre Legendre. "Shifts between biotic and physical driving forces of species organization under natural disturbance regimes". Canadian Journal of Fisheries and Aquatic Sciences 66, n.º 8 (agosto de 2009): 1282–93. http://dx.doi.org/10.1139/f09-075.
Resumen
The high ecological values (i.e., the benefits that space, water, minerals, biota, and all other factors that make up natural ecosystems provide to support native life forms) and diversities found in tropical islands emphasize the importance of incorporating disturbance into ecological models. This is of major concern in appreciating how species will survive and adapt to changes and the consequences expected in terms of biodiversity. We predicted that in lotic systems, modification to natural disturbance regimes (fluvial action) would have strong consequences on community organization, with strong disturbance regimes reducing species competitive exclusion through changes in space occupation. We tested this prediction by relating microdistribution data from a crustacean species ( Atya innocous , Decapoda, Atyidae) in small and large rivers in Guadeloupe to two, independently obtained sets of explanatory variables describing the physical environment, as well as the crustacean and fish competitors. Our results show that in rivers with high-energy flow, the driving forces for species coexistence were mostly environmental, whereas in rivers with low-energy flow, biotic interactions were prevalent. These differences linked to natural disturbance regimes revealed that disturbance was a stochastic factor, overlying the classical community-structuring factors and affecting global species relationships.
34
Magee, Darrin. "Hydropower and End-Use Electrical Efficiency in China: State Support and Potential Contribution to Low-Carbon Development". Copenhagen Journal of Asian Studies 33, n.º 1 (16 de junio de 2015): 64–89. http://dx.doi.org/10.22439/cjas.v33i1.4812.
Resumen
This article examines Chinese state support for two 'new energies'—large hydropower and end-use efficiency—that aims to help meet ambitious national targets for renewable energy and emissions reduction. Large hydropower, while not particularly new, figures prominently in China's renewable energy targets and is considered key to achieving renewable output and carbon reduction goals. National policies promote widespread development of Gigawatt-scale hydropower cascades on China's major rivers, even though the negative impacts are significant and the operating capacities of large dams are often low. On transboundary rivers, China's dam development raises concerns downstream.
Increasing the end-use efficiency of electricity represents a more subtle approach that holds great promise for managing demand and potentially curbing new supply. China's National Development and Reform Commission (NDRC) has overseen experimentation with utility-scale 'efficiency power plants' that free up inefficiently-used electricity, resulting in greater power availability on the grid. A study by NDRC's Energy Research Institute (ERI) estimated that a high penetration rate of LED lighting by 2020, once China completes its phase-out of incandescent bulbs, would alone save as much electricity annually as the Three Gorges Dam produces. This article demonstrates the potential for an efficiency-led approach to meeting China's electricity needs.
35
Costa Silva, Diogo F., Arlindo R. Galvão Filho, Rafael V. Carvalho, Filipe de Souza L. Ribeiro y Clarimar J. Coelho. "Water Flow Forecasting Based on River Tributaries Using Long Short-Term Memory Ensemble Model". Energies 14, n.º 22 (17 de noviembre de 2021): 7707. http://dx.doi.org/10.3390/en14227707.
Resumen
Water flow forecasts are an essential information for energy production, management and hydropower control. Advanced actions to optimize electricity production can be taken based on predicted information. This work proposes an ensemble strategy using recurrent neural networks to generate a forecast of water flow at Jirau Hydroelectric Power Plant (HPP), installed on the Madeira River in Brazil. The ensemble strategy consists of combining three long short-term memory (LSTM) networks that model the Madeira River and two of its tributaries: Mamoré and Abunã rivers. The historical data from streamflow of the Madeira river and its tributaries are used to validate the ensemble LSTM model, where each time series of river tributaries are modeled separated by LSTM models and the result used as input for another LSTM model in order to forecast the streamflow of the main river. The experimental results present low errors for training and test sets for individual LSTM networks and ensemble model. In addition, these results were compared with the operational forecasts performed by Jirau HPP. The proposed model showed better accuracy in four of the five scenarios tested, which indicates a promising approach to be explored in water flow forecasting based on river tributaries.
36
Coates, D. "Observations on the biology of tarpon, Megalops cyprinoides (Broussonet) (Pisces : Megalopidae), in the Sepik River, Northern Papua New Guinea". Marine and Freshwater Research 38, n.º 4 (1987): 529. http://dx.doi.org/10.1071/mf9870529.
Resumen
M. cyprinoides was recorded in higher-order rivers, ox-bow lakes and other areas of permanent water and also on the floodplain, although this is not a preferred habitat. Juveniles enter the river in April to July and the fish return to the sea before they begin to mature. The smallest individual recorded was 103 mm, the largest 440 mm (standard length). Fat deposit index was low for the whole population and surplus energy is probably directed to growth and not stored. Condition and fat deposit index were both slightly, but significantly, lower during the dry season. Stomach contents showed that this species is a meso-predator, feeding mainly on small prawns, aquatic and terrestrial insects and small fish. No major seasonal changes in diet were evident.
37
Norris, Darren, Fernanda Michalski y James P. Gibbs. "Beyond harm’s reach? Submersion of river turtle nesting areas and implications for restoration actions after Amazon hydropower development". PeerJ 6 (8 de enero de 2018): e4228. http://dx.doi.org/10.7717/peerj.4228.
Resumen
The global expansion of energy demands combined with abundant rainfall, large water volumes and high flow in tropical rivers have led to an unprecedented expansion of dam constructions in the Amazon. This expansion generates an urgent need for refined approaches to river management; specifically a move away from decision-making governed by overly generalized guidelines. For the first time we quantify direct impacts of hydropower reservoir establishment on an Amazon fresh water turtle. We conducted surveys along 150 km of rivers upstream of a new dam construction during the low water months that correspond to the nesting season of Podocnemis unifilis in the study area. Comparison of nest-areas before (2011, 2015) and after (2016) reservoir filling show that reservoir impacts extend 13% beyond legally defined limits. The submerged nesting areas accounted for a total of 3.8 ha of nesting habitat that was inundated as a direct result of the reservoir filling in 2016. Our findings highlight limitations in the development and implementation of existing Brazilian environmental impact assessment process. We also propose potential ways to mitigate the negative impacts of dams on freshwater turtles and the Amazonian freshwater ecosystems they inhabit.
38
Liffen, T., A. M. Gurnell, M. T. O’Hare, N. Pollen-Bankhead y A. Simon. "Biomechanical properties of the emergent aquatic macrophyte Sparganium erectum: Implications for fine sediment retention in low energy rivers". Ecological Engineering 37, n.º 11 (noviembre de 2011): 1925–31. http://dx.doi.org/10.1016/j.ecoleng.2011.06.015.
39
Lespez, L., V. Viel, A. J. Rollet y D. Delahaye. "The anthropogenic nature of present-day low energy rivers in western France and implications for current restoration projects". Geomorphology 251 (diciembre de 2015): 64–76. http://dx.doi.org/10.1016/j.geomorph.2015.05.015.
40
Ünsalan, Deniz. "Parametric analysis of gravity Vortex turbines as a low cost renewable energy alternative from low head hydraulic resources". Scientific Bulletin of Naval Academy XXIII, n.º 1 (15 de julio de 2020): 22–28. http://dx.doi.org/10.21279/1454-864x-20-i1-003.
Resumen
The long existent worldwide trend for large scale hydroelectric power plants, relying on dams are now under severe criticism for the large areas their reservoirs occupy, which are often fertile agricultural areas and sometimes flood cultural heritage sites. However, there are also environment-friendly alternatives for hydroelectric power production, which are capable to obtain energy from small scale streams with relatively low heads. Such smaller scale sources with low cost facilities can be used for electric production by alternative schemes that use small streams, irrigation canals and divertions from rivers, tidal pools, overtopping wave energy converters and urban wastewater. One of the recent types of such plants are the gravity vortex turbines that use the naturally occurring “sink vortex” draining such water. They are highly efficient and able to obtain energy from sources with flow rates as low as 1 m3/s and heads as low as 0.80 m. Such water sources are abundant in most of the rural areas and it is possible to obtain either an important part or the total need of the energy requirement of the nearby communities with such systems. Gravity vortex turbines have low costs due to their simple structure and are easy to maintain. They can also be implemented for overtopping wave energy and tidal energy systems, as well as recovery units of pumped energy storage schemes. The purpose of this paper is to propose relations for the design and parametric analysis to size the relevant parts of the plant- the pool and the turbine. Potential flow is assumed throughout the analysis. Attempts to obtain optimized relations between the relative sizes and rotational speeds for the pool, water source, turbine are made and inputs for preliminary design are obtained.
41
Kurbanov, S. O. y A. A. Sozaev. "NEW DESIGN AND PROCESS SOLUTIONS FOR WATER INTAKE STRUCTURES OF RECLAMATION SYSTEMS IN FOOTHILL AREAS". Water and Ecology 25, n.º 4 (2020): 24–31. http://dx.doi.org/10.23968/2305-3488.2020.25.4.24-31.
Resumen
Introduction. Efficient and reliable operation of water intake structures within reclamation systems in Southern Russia and the North Caucasus is a challenging issue. In this article, we address the operational reliability of reclamation water intakes in the foothill areas of small rivers. Many water intake structures built on small rivers are in poor operating condition and, therefore, need improvement and complete reconstruction. Methods. We performed analytical and field studies on the head structures of foothill reclamation systems. Based on the results, we identified the reasons for the low efficiency and reliability of old water intake structures. Since it is impossible to improve these water intake structures, new types and designs of high-performance water intakes are required. Therefore, we propose some original types of underground horizontal and underflow water intakes and determine corresponding technical parameters and performance criteria. Results. Due to low efficiency as well as high energy and material consumption of existing water intake structures, it is required to significantly reduce the cost of supplied irrigation water by introducing new types of high-performance water intake structures. Based on the studies of alluvial regimes of rivers and retention basins as well as hydraulic regimes of head water intake structures, we prepared design and process solutions that help control sediment effectively, increase the water intake coefficient, and regulate water supply to irrigation canals. The design features of new water intakes have a beneficial effect on river flows and the quality of irrigation water. Conclusion. The study results confirm the high performance and manufacturability of the proposed horizontal and underflow water intakes protected by patents for inventions. This year, our designs have been included in the state grant program for the development of standard hydraulic structures within reclamation systems.
42
Goshovskyi, S. y O. Zurian. "ENVIRONMENTALLY SAFE USAGE OF HYDROPOWER POTENTIAL BY HYDROTHERMAL POWER SUPPLY SYSTEMS". Visnyk of Taras Shevchenko National University of Kyiv. Geology, n.º 4 (87) (2019): 67–75. http://dx.doi.org/10.17721/1728-2713.87.10.
Resumen
The article contains the results of scientific research and design work related to environmentally safe usage of hydropower potential of the small rivers of the Dnieper basin. The innovative design solutions for extraction of low-grade heat energy of water and systems for its transformation into energy convenient for consumption were offered. It was established that use of renewable low-grade energy of soil is widely used in environmentally safe and economically sound power systems. At the same time hydropower potential is not widely used in hydrothermal heat pump systems. It was proved that existing hydrothermal systems are not always adjusted to actual operating conditions and object location. The evidence was provided that the scientific approach to development of appropriate configuration of hydrothermal collector, to methodology of their optimal mounting and to efficiency determination depending on operating conditions is quite topical issue. The scientific novelty of the new process approach is use of special design of water collector that has modular configuration and consists of several functionally related water sondes. The efficiency of hydrothermal system was scientifically proved. The paper describes the results of experimental research of efficiency of hydrothermal heat pump system where the low-grade heat energy of water is used as a renewable primary heating energy source for functioning of the heat pump. The authors have developed experimental hydrothermal and geothermal heat pump systems to conduct the research. Both collector and ground section of the system have mounted sensors of temperature, pressure and coolant flow velocity. The software for archiving and visualization of obtained data was developed. The research procedure was developed. As part of study, observation data were received and performance efficiency of geothermal and hydrothermal systems was calculated. The comparative analysis of energy systems depending on used renewable energy source was carried out. The conclusion was made that use of hydrothermal heat pump systems is environmentally safe. The data obtained as part of study have great scientific and applied significance for engineering of heat pump energy systems using hydropower potential of the small rivers.
43
Cavalaglio, Gianluca, Franco Cotana, Andrea Nicolini, Valentina Coccia, Alessandro Petrozzi, Alessandro Formica y Alessandro Bertini. "Characterization of Various Biomass Feedstock Suitable for Small-Scale Energy Plants as Preliminary Activity of Biocheaper Project". Sustainability 12, n.º 16 (18 de agosto de 2020): 6678. http://dx.doi.org/10.3390/su12166678.
Resumen
The PRIN (Research Project with Relevant National Interest) project “Biocheaper—biomasses circular holistic economy approach to energy equipments” started in September 2019 and involves several universities: Palermo as the university coordinator, Perugia, Cassino, Enna, Pavia and Bolzano. The main goal of the project is to increase the energy efficiency and reduce the pollutants emissions in small-scale biomass plant for energy (heat and power) production. The project focuses on residual lignocellulosic feedstocks from the agriculture and forestry sector, from energy crops in marginal lands and residues from rivers maintenance. Starting from the selection and characterization of potential feedstocks, the project aims at developing some prototypes for retrofit applications in existing biomass boilers, like a mini-cyclone for the reduction of particulate emissions and an exhaust air-water condensing system for the recovery of water and the reuse in agriculture. This work presents the first results of the project, in particular regarding the selection and the chemical–physical characterization of different biomass, available in different zones of Italy; in particular the authors investigated cardoon chips, carthamus chips, olive and wine pruning, residues from rivers maintenance. Each biomass sample was characterized in terms of moisture content, ashes content, volatile substances, fixed carbon, low and high heating value, content of carbon, nitrogen, hydrogen and main metals.
44
Yang, Xiao Feng, Yong Kang, Xiao Chuan Wang, Deng Li y Zhen Fang Liao. "Technical Principle and Working Properties of Sludge Dredging by Airlift Water Jet". Advanced Materials Research 683 (abril de 2013): 585–88. http://dx.doi.org/10.4028/www.scientific.net/amr.683.585.
Resumen
The sludge in rivers, dams and municipal facilities have caused increasing attentions. The airlift water jet can make density difference between sludge and the environment, and make the sludge float automatically. A kind of airlift water jet dredging system is designed and its work properties are analyzed. Mechanical structure analysis shows that the airlift water jet dredging device is low energy consumption and easy of maintenance with low cost. Numerical Simulation shows that the bubble volume ratio will affect the flow performance: the bigger bubble volume ratio will generate higher transport capacity.
45
Cai, Rongrong, Hongwu Zhang, Yu Zhang, Luohao Zhang y Hai Huang. "Flow Resistance Equation in Sand-bed Rivers and Its Practical Application in the Yellow River". Water 12, n.º 3 (6 de marzo de 2020): 727. http://dx.doi.org/10.3390/w12030727.
Resumen
To fully reflect the effect of the flow characteristics, sidewall conditions and sediment concentrations on the bed roughness of sand-bed rivers, this study established a new flow resistance equation by introducing a comprehensive influence coefficient presented via a combination of power-function forms of the relative flow velocity, von Karman constant of sediment-laden flows and the ratio of particle size to viscous sublayer thickness. The comprehensive influence coefficient accordingly acts as a synthesized factor representing the combined effects of the flow intensity, bed material movement, energy consumption condition, and relative friction condition in the near-wall region of sediment-laden flows. Based on the field data from sediment-laden flows under scenarios of both high and low sediment concentrations, the performance of the proposed equation was validated to achieve the best accuracy in the calculation of Manning’s roughness coefficient compared with that of several previously presented flow resistance equations. Furthermore, the proposed flow resistance equation was adopted to quantify the stable channel width of the Lower Yellow River (LYR), i.e., the optimum main channel width for sediment transportation in the typical wandering reach of the LYR. The calculated stable channel width is consistent with the current river training width of the LYR, indicating that the proposed equation has great potential as a theoretical tool that can be used to support the determination of the river training strategy for the LYR.
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Martins-Oliveira, A. T., L. E. S. Stefanello, T. M. Santos, V. R. Pinto, C. A. Souza y J. B. Sousa. "Morphological, physical and chemical attributes of the soil profile to the right margin of the Paraguay river, Baia da Campina, Cáceres (MT)". Scientific Electronic Archives 13, n.º 10 (30 de septiembre de 2020): 61. http://dx.doi.org/10.36560/131020201076.
Resumen
The fluvial dynamics corresponds to the natural changes of river channels that can influence the water energy, type and morphology of the gutter, geological structure and soil types. In this context, the type of soil present on the banks of the rivers stands out, which due to their morphological, physical and chemical characteristics, will offer greater or less resistance to marginal erosive processes. Whit this study, we aim to verify the contribution of soil morphological, physical and chemical attributes in the natural dynamics of the right bank of the Paraguay River. The studied area is located in the Pantanal Matogrossense, sub-region of Cáceres, and comprises the right bank of the Paraguay River, in the region of Baia da Campina, approximately 10 km away from the municipality of Cáceres, Mato Grosso, Brazil. We carry out morphological, granulometric and chemical description of the soil. The data were tabulated in a spreadsheet, being subsequently analyzed and discussed. The vegetation occurring in the study area is of the seasonal / cerrado and alluvial forests type, with the presence of low and semi-shrub vegetation. We classified the soil profile in the section studied as Fluvic Tb Endoeutrophic Neosol, presenting medium texture and, in general, high levels of sand and low levels of clay. The values referring to the effective cation exchange capacity (CTC) obtained in this study, were classified from low to very good, a characteristic that allows the existence of low and semi-shrubby vegetation, which contributes to the resistance to erosive processes, even that the soil has a low presenting resistance physical structure.
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Pamuji, D. S., F. Akbar, A. N. Rohman y D. Sugati. "Studi eksperimen kinerja turbin vortex berbasis gravitasi dengan sudu backward dan forward". Dinamika Teknik Mesin 11, n.º 1 (1 de abril de 2021): 74. http://dx.doi.org/10.29303/dtm.v11i1.429.
Resumen
Nowadays, the use of hydro energy in Indonesia is still focused on large-scale hydropower development which has negative effects on the environment such as changes in the natural flow of rivers, disruption of the population of aquatic biota that live in these watersheds and has the risk of potential disasters if the dam fails. In fact, the energy potential from the mini-micro hydro source is 19,835 MW, but its utilization is still very low around 100 MW. Therefore, the extraction of water flow energy in the form of rivers and irrigation channels with very low head altitude differences is considered important and urgent so that a gravity vortex turbine-based mini / micro hydro research is proposed. Specifically, this study aims to analyze the performance of the vortex turbine with backward and forward blades in a conical basin through laboratory experimental devices. Experiments were carried out on a fluid flow rate of 120 liters per minute (lpm) and 100 lpm by loading using a prony brake dynamometer in order to obtain torque performance data on variations in turbine blade rotational speed. In this experiment, the results showed that the performance of the backward blade turbine was superior with its optimal efficiency reaching 36.7% at a discharge of 120 lpm and a rotating speed of 80 rpm than the forward blade which at a discharge of 120 lpm and a rotating speed of 80 rpm was only able to achieve its highest efficiency at 33.19%.
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Dick, Jonathan J., Doerthe Tetzlaff y Chris Soulsby. "Role of riparian wetlands and hydrological connectivity in the dynamics of stream thermal regimes". Hydrology Research 49, n.º 3 (13 de noviembre de 2017): 634–47. http://dx.doi.org/10.2166/nh.2017.066.
Resumen
Abstract Stream temperature is a fundamental physical characteristic of rivers, influencing biological productivity and water quality. Given the implications of climate warming for stream thermal regimes, it is an important consideration in river management plans. Energy exchanges at the water–air interface, channel geomorphology, riparian vegetation and advective heat transport from the different sources of discharge can all influence stream temperature. A simple mixing equation was used to investigate heat transport and to estimate daily mean and maximum stream temperatures on the basis of mixing groundwater and near-surface flows from riparian wetlands as end-members in a peatland catchment. The resulting data were evaluated against energy balance components and saturation extent to investigate the importance of riparian wetlands in determining stream temperatures. Data fit was generally good in periods with extensive saturation and poorest in dry periods with less hydrological connectivity, when reduced saturation and low flows increased the relative influence of energy exchange at the stream–atmosphere interface. These findings have implications in terms of climate change and land management, where the planting of riparian buffer strips to moderate water temperatures may be less effective when saturation area is extensive and hydrological connectivity is high.
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Brooks, G. R. y D. E. Lawrence. "Geomorphic Effects of Flooding Along Reaches of Selected Rivers in the Saguenay Region, Québec, July 1996". Géographie physique et Quaternaire 54, n.º 3 (2 de octubre de 2002): 281–99. http://dx.doi.org/10.7202/005639ar.
Resumen
AbstractA severe rainstorm from July 18 to 21, 1996, caused widespread flooding along many rivers in southern Québec, particularly in the Lac-Saint-Jean-Chicoutimi area, along north-flowing tributaries of the Rivière Saguenay. Along study reaches located on the Rivière aux Sables, Rivière Chicoutimi, Rivière du Moulin and Rivière à Mars, the fluvial geomorphic effects of flooding varied considerably, reflecting differing channel morphologies (alluvial, non-alluvial and bedrock), flow energy, and the interaction of floodwaters and infrastructure. Catastrophic channel widening and floodplain reworking occurred along the Rivière à Mars study reach, transforming the river from a meandering to braided planform. Consistent with this, unit stream power of the flood flow exceeded the minimum erosive threshold (300 Wm-2) along most of the study reach. Morphological and empirical evidence indicates that the pre-flood Rivière à Mars channel exhibited a transitional planform, and thus was vulnerable to a planform transformation during an extreme flood. The most significant geomorphic effects along the Rivière aux Sables and Rivière Chicoutimi study reaches occurred at a number of run-of-the-river dams. Floodwaters overtopped four dams and eroded deeply into unconsolidated sediments adjacent to the dams, forming new channels that captured the flow of the river. Floodwaters also overtopped a fifth dam, scouring overburden and road beds, and damaging and destroying buildings within an urban subdivision. Elsewhere along these two rivers, as well as along the Rivière du Moulin study reach, there were localized erosional problems, particularly at bridges, but the geomorphic effects generally were limited or negligible, reflecting either low unit stream power or resistant substrates.
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Copping, Andrea E., Lenaïg G. Hemery, Dorian M. Overhus, Lysel Garavelli, Mikaela C. Freeman, Jonathan M. Whiting, Alicia M. Gorton, Hayley K. Farr, Deborah J. Rose y Levy G. Tugade. "Potential Environmental Effects of Marine Renewable Energy Development—The State of the Science". Journal of Marine Science and Engineering 8, n.º 11 (4 de noviembre de 2020): 879. http://dx.doi.org/10.3390/jmse8110879.
Resumen
Marine renewable energy (MRE) harnesses energy from the ocean and provides a low-carbon sustainable energy source for national grids and remote uses. The international MRE industry is in the early stages of development, focused largely on tidal and riverine turbines, and wave energy converters (WECs), to harness energy from tides, rivers, and waves, respectively. Although MRE supports climate change mitigation, there are concerns that MRE devices and systems could affect portions of the marine and river environments. The greatest concern for tidal and river turbines is the potential for animals to be injured or killed by collision with rotating blades. Other risks associated with MRE device operation include the potential for turbines and WECs to cause disruption from underwater noise emissions, generation of electromagnetic fields, changes in benthic and pelagic habitats, changes in oceanographic processes, and entanglement of large marine animals. The accumulated knowledge of interactions of MRE devices with animals and habitats to date is summarized here, along with a discussion of preferred management methods for encouraging MRE development in an environmentally responsible manner. As there are few devices in the water, understanding is gained largely from examining one to three MRE devices. This information indicates that there will be no significant effects on marine animals and habitats due to underwater noise from MRE devices or emissions of electromagnetic fields from cables, nor changes in benthic and pelagic habitats, or oceanographic systems. Ongoing research to understand potential collision risk of animals with turbine blades still shows significant uncertainty. There has been no significant field research undertaken on entanglement of large animals with mooring lines and cables associated with MRE devices.