Run-of-the-river Research Articles

Climate change impact on hydropower generation and adaptation through reservoir operation in a Himalayan river, Tamor

ABSTRACT Integrated assessment of climate change impact and water resource development scenario is crucial for planning and management. In the Himalayan river basin, it is of utmost importance considering the vulnerability to climate change and the pace of water resource development. This study focused on Tamor river basin (TRB), investigating the impacts of climate change on the energy generation from hydropower projects and analyzes the adaptation through reservoir operation. Analyzing the three run-of-river (RoR) hydropower projects and a storage project, this study projects future energy generation. Results showed that RoR is highly susceptible to the impacts, demonstrated by significant reduction during pre-monsoon up to -53% and increment at annual scale up to 28%. In Tamor storage project, the particle-swarm optimization approach generated operational strategies according to altered streamflow conditions. This resulted in adaptation to the projected decrease in March-June flow through flexible operation rules, yielding positive impact on energy generation (up to +7.3% on an annual scale). The new set of rules will adapt to the flow deficit and increase the dry season flow downstream, almost by double than the historical baseline. This research highlights the significance of reservoir project and its optimized operation in effectively managing water under changing climate.

Feasibility of small-scale multipurpose hydropower projects in Karbi-Anglong District of Assam, India: a geotechnical appraisal

ABSTRACT The potential of small hydropower projects (SHP) in Karbi-Anglong District of Assam has been investigated, and site-specific detailed studies have been done at three potentially feasible sites. Geo-mechanical characterization of rocks at the proposed sites shows higher values for strength parameters and falls in Good rock category in Rock Mass Rating class. Run of the River (RoR) scheme with a small reservoir is recommended in the area. A storage type layout plan for the site located on Kalyani river would have a 2.38 MW power-generation capacity, whereas the RoR type would be able to generate 953.1 kW. The RoR scheme for the Daigurung site will be able to generate 175.8 kW and that for Nambar 53.0 kW. Likewise, the storage type scheme will produce 505.4 kW and 137.7 kW for Daigurung and Nambar sites, respectively. These irrigation-based multipurpose projects will boost agriculture activities in the downstream areas and also meet the captive power requirement.

Statistical analysis of electricity supply deficits from renewable energy sources across an Alpine transect

While most of renewable integration studies rely on indicators that are integrated in time, little is known about the statistical properties of the electricity supply deficit periods. This study investigates the frequency and intensity of the electricity supply deficit using the Complete-Time-Analysis (CTA), an approach that allows assessing recurrence intervals of values over thresholds. Conversely to typical extreme analysis, CTA makes uses of the entire time series rather than only using values above the chosen thresholds. As such, it is suitable for short length time series and does not require the independence of the events above thresholds. Intensity-Duration-Frequency (IDF) curves are derived for the considered renewable sources and the role of the complementarity among sources and the use of electricity storage is investigated to reduce the occurrence of electricity supply deficit. The approach is illustrated for a region in North-Eastern Italy where solar photovoltaic (PV) and small run-of the river (RoR) hydropower are the main sources of electricity. Our results highlight that solar PV and small electricity storage capacities are effective to reduce significantly the occurrence of deficits, and RoR hydropower and large electricity storage is more effective to prevent long periods of deficit from happening.

Sacrificing the local to support the national: Politics, sustainability, and governance in Nepal’s hydropower paradox

Developing run-of-the-river (ROR) hydropower can pose a sustainability paradox. The paradox can occur when countries prioritize hydropower development to achieve national-level sustainable development targets while failing to include project-affected communities in planning processes. This research developed a comparative study examining the ways social and political relations were articulated between hydropower companies and project-affected communities across 12 ROR hydropower sites in the Gandaki River basin of Nepal. The study details how the introduction of hydropower can feasibly offer local communities coveted benefits such as increased water and electricity access and availability. Outcomes of ROR hydropower development, however, were not uniform across study sites and spatially uneven development was manifest. Consequently, many of Nepal’s ROR hydropower projects exacerbate social and political inequalities in Nepal’s mountain river basins, which in turn fuel hydropower driven conflicts. Drawing on theories of global change, energy justice, and political ecology, this research highlights opportunities currently being neglected in Nepal to bring local communities into processes linked to national sustainable development goals and targets and to address injustices embedded in the development of ROR hydropower resources.

Impact of Flow Variation on Hydropower Projects in Budhigandaki River Basin of Nepal

Daily flow data from 1964 to 2015 of Budhigandaki River at Arughat were analyzed to assess the impact of flow variation at different time scales to the run of the river (RoR) type of hydropower projects. The data show very high inter-annual variation in daily, monthly and seasonal flows. The long term annual average flow at Arughat was 160 m3/s and varies from 120 to 210 m3/s. The long-term averages of loss in flow for both dry and wet seasons based on daily flows for three design discharges (Q90, Q60 and Q40) were found to be respectively -0.72, -1.76 and -1.54 m3/s for dry season and 0.0, -0.27 and -2.26 m3/s for wet season. Although long-term average loss is small, uncertainty increases with the increase in design discharge. The long-term dry season power loss is about 3 % for the RoR projects of the basin however, its annual variation is large. There is a probability of losing the quantum of energy generation by nearly 40% in some years and gaining by about 30 % in some other years in dry season. The impact of flow variation on power production was negative in both dry and wet seasons for RoR projects of Budhigandaki basin. This study concludes that uncertainty arising from daily flow variation should be assessed while estimating energy generation in hydropower projects. Intra-annual flow variation is, thus, to be taken into consideration while calculating the power generated by the RoR plants; and it should be reflected in power purchase agreement.

Low Diffusive Methane Emissions From the Main Channel of a Large Amazonian Run-of-the-River Reservoir Attributed to High Methane Oxidation

The global development of hydropower dams has rapidly expanded over the last several decades and has spread to historically non-impounded systems such as the Amazon River’s main low land tributaries in Brazil. Despite the recognized significance of reservoirs to the global methane (CH4) emission, the processes controlling this emission remain poorly understood, especially in Tropical reservoirs. Here we evaluate CH4 dynamics in the main channel and downstream of the Santo Antônio hydroelectric reservoir, a large tropical run-of-the-river (ROR) reservoir in Amazonia. This study is intended to give a snapshot of the CH4 dynamics during the falling water season at the initial stage after the start of operations. Our results show substantial and higher CH4 production in reservoirs’ littoral sediment than in the naturally flooded areas downstream of the dam. Despite the large production in the reservoir or naturally flooded areas, high CH4 oxidation in the main channel keep the concentration and fluxes of CH4 in the main channel low. Similar CH4 concentrations in the reservoir and downstream close to the dam suggest negligible degassing at the dam, but stable isotopic evidence indicates the presence of a less oxidized pool of CH4 after the dam. ROR reservoirs are designed to disturb the natural river flow dynamics less than traditional reservoirs. If enough mixing and oxygenation remain throughout the reservoir’s water column, naturally high CH4 oxidation rates can also remain and limit the diffusive CH4 emissions from the main channel. Nevertheless, it is important to highlight that our results focused on emissions in the deep and oxygenated main channel. High emissions, mainly through ebullition, may occur in the vast and shallow areas represented by bays and tributaries. However, detailed assessments are still required to understand the impacts of this reservoir on the annual emissions of CH4.

A Hybrid Method for the Run-Of-The-River Hydroelectric Power Plant Energy Forecast: HYPE Hydrological Model and Neural Network

The increasing penetration of non-programmable renewable energy sources (RES) is enforcing the need for accurate power production forecasts. In the category of hydroelectric plants, Run of the River (RoR) plants belong to the class of non-programmable RES. Data-driven models are nowadays the most widely adopted methodologies in hydropower forecast. Among all, the Artificial Neural Network (ANN) proved to be highly successful in production forecast. Widely adopted and equally important for hydropower generation forecast is the HYdrological Predictions for the Environment (HYPE), a semi-distributed hydrological Rainfall–Runoff model. A novel hybrid method, providing HYPE sub-basins flow computation as input to an ANN, is here introduced and tested both with and without the adoption of a decomposition approach. In the former case, two ANNs are trained to forecast the trend and the residual of the production, respectively, to be then summed up to the previously extracted seasonality component and get the power forecast. These results have been compared to those obtained from the adoption of a ANN with rainfalls in input, again with and without decomposition approach. The methods have been assessed by forecasting the Run-of-the-River hydroelectric power plant energy for the year 2017. Besides, the forecasts of 15 power plants output have been fairly compared in order to identify the most accurate forecasting technique. The here proposed hybrid method (HYPE and ANN) has shown to be the most accurate in all the considered study cases.

Complementarity between Combined Heat and Power Systems, Solar PV and Hydropower at a District Level: Sensitivity to Climate Characteristics along an Alpine Transect

Combined heat and power systems (CHP) produce heat and electricity simultaneously. Their resulting high efficiency makes them more attractive from the energy managers’ perspective than other conventional thermal systems. Although heat is a by-product of the electricity generation process, system operators usually operate CHP systems to satisfy heat demand. Electricity generation from CHP is thus driven by the heat demand, which follows the variability of seasonal temperature, and thus is not always correlated with the fluctuation of electricity demand. Consequently, from the perspective of the electricity grid operator, CHP systems can be seen as a non-controllable energy source similar to other renewable energy sources such as solar, wind or hydro. In this study, we investigate how ‘non-controllable’ electricity generation from CHP systems combines with ‘non-controllable’ electricity generation from solar photovoltaic panels (PV) and run-of-the river (RoR) hydropower at a district level. Only these three energy sources are considered within a 100% renewable mix scenario. Energy mixes with different shares of CHP, solar and RoR are evaluated regarding their contribution to total energy supply and their capacity to reduce generation variability. This analysis is carried out over an ensemble of seventeen catchments in North Eastern Italy located along a climate transect ranging from high elevation and snow dominated head-water catchments to rain-fed and wet basins at lower elevations. Results show that at a district scale, integration of CHP systems with solar photovoltaic and RoR hydropower leads to higher demand satisfaction and lower variability of the electricity balance. Results also show that including CHP in the energy mix modifies the optimal relative share between solar and RoR power generation. Results are consistent across the climate transect. For some districts, using the electricity from CHP might also be a better solution than building energy storage for solar PV.

Hydropower Potential in the Alps under Climate Change Scenarios. The Chavonne Plant, Val D’Aosta

Present and prospective climate change will likely affect the hydrological cycle in sensitive areas, such as the Alps, thus impacting water-based activities. A most representative example is hydropower production, i.e., exploitation of water to produce energy. In the Italian Alps hydropower is strictly dependent upon water from snow and ice melt, and both are decreasing in response to global warming. Here, we study the effects of potential climate change scenarios at 2100 upon hydropower production from the Chavonne plant, in Valle d’Aosta region of Italy, a run-of-the-river (ROR) plant taking water from two high altitude glacierized catchments of Val di Cogne, and Valsavarenche. We use Poli-Hydro, a state-of-the-art hydrological model to mimic the hydrological budget of the area, including ice and snow melt share. Projections of the hydrological budget were built until 2100 by means of selected climate change scenarios, under proper downscaling. We used runs of three General Circulation Models (GCMs), EC-Earth, CCSM4, and ECHAM6.0 under three Representative Concentration Pathways RCP 2.6, RCP 4.5, and RCP 8.5 from AR5 of IPCC, and of their updated version under four Shared Socio-Economic Pathways SSP1 2.6, SSP2 4.5, SSP3 7.0, and SSP5 8.5 from AR6. We then assessed hydropower production changes against a recent control run CR period (2005–2015). Mean annual flow is estimated at 14.33 m3 s−1 during CR, with ice melt contribution ca. 2%, and snow melt contribution ca. 44%. Ice cover in 2005 was estimated as 19.2 km2, reaching in 2015, 9.93 km2. Mean hydropower production was estimated at 153.72 GWh during the CR. Temperature would largely increase throughout the century (+0.93 °C on average at the half century, +2.45 °C at the end of the century). The ice covered area would be largely depleted (ca. −86%, −94% respectively), with reduced contribution of ice melt (0.23%, <0.1%, respectively) and snow melt (ca. 37%, 33%, respectively). Precipitation would show uncertain patterns, and hence incoming discharge at the plant would erratically vary (−29% to +24% half century, −27% to +59% end of century). Hydropower production displays a large dependence upon monthly discharge patterns, with mostly positive variations (+2.90% on average at half century, +6.95% on average at end of century), with its change driven by exceedance of plant’s capacity.

The biotic condition of dams run-of-the-river in sequence: adaptation of a multimetric index based on the Neotropical fish fauna.

The synergistic effects of run-of-the-river (ROR) on fish fauna, though still poorly understood, are amplified when dams form reservoir cascades. In an attempt to assist in this understanding, we used an adaptation of the Reservoir Fish Assemblage Index (RFAI) to evaluate the biotic conditions of the Rio das Antas Energy Complex, in the Neotropical Patos Lagoon ecoregion. We evaluated the attributes of the fish fauna from the point of view of the complex, for each reservoir and between different sections. Fish samplings were performed quarterly at nine sites for 2years (2015-2017). We proposed 26 metrics, related to aspects of composition, reproduction, feeding, habitat, and tolerance, selected based on criteria of variability, responsiveness, and redundancy. The final RFAI score was distributed in four categories of biological status, based on the best-observed condition. Eight metrics composed the final index, among which, only the proportion of nektonic individuals + nektobenthic (PNNbI) correlated with all sections. The final RFAI was classified as poor in all sections of the reservoir cascade, showing no significant differences between the sampling sites. This scenario indicates that dams in sequence intensify and homogenize the amplitude of fragmentation impacts on fish fauna. The final RFAI proved to be representative of the transition sections, emphasizing the importance of these reaches in impounded environments. Although the disturbance scales presented here are applicable mainly to ROR systems with reduced discharge section, the index was developed so as to allow its replicability in any dammed water course.

Characterizing Density Flow Regimes of Three Rivers with Different Physicochemical Properties in a Run-Of-The-River Reservoir

Inflow mixing affects the spatiotemporal heterogeneity of water quality in reservoirs. Reservoir water quality management requires accurate prediction of density flow regimes to understand the spatiotemporal distribution of dissolved and particulate nutrients and organics. This study aims to characterize the mixing and circulation of three rivers with different physicochemical properties in a run-of-the-river (ROR) reservoir, using high-frequency monitoring and three-dimensional (3D) hydrodynamic modeling. The Aquatic Ecosystem Model (AEM3D) was constructed for the reservoir and calibrated with high-frequency data obtained from May–June 2016, accurately reproducing the observed spatiotemporal variations of flow velocity, water temperature, and electrical conductivity (EC) in the reservoir. High-frequency data and 3D model results showed that mixing of the rivers in the ROR reservoir is governed by density flow regimes formed by influent water temperature differences. At the confluence, colder and warmer river influents formed underflows and surface buoyant overflows, respectively. The spatial arrangement of flow direction, water residence time, and EC concentration were largely controlled by the buoyancy-driven flow. Stagnant areas with long residence times corresponded with areas of observed algal blooms and hypoxia. High-frequency sensor technology, combined with 3D hydrodynamic modeling, is effective for understanding the complex flow regimes and associated water quality characteristics in ROR-type reservoirs.

Temples, travesties, or something else? The developmental state, ecological modernization, and hydroelectric dam construction in India

Abstract Hydroelectric power is the world’s largest source of renewable energy. It can encourage economic development while reducing carbon emissions, but large hydroelectric projects have serious social and environmental consequences. Democratic Developmental and Ecological Modernization theorists counseled the adoption of new regulations and institutions to increase citizen participation and socioenvironmental protection. Environmental impact assessments (EIAs) and public audiences are considered best practice, but do these new protections and procedures alter government behavior when it makes critical development decisions? We argue scholars have paid too little attention to how bureaucratic hierarchies and weak cross-agency harmonization weaken environmental regimes. To highlight these issues, we provide an in-depth case study of hydroelectric dam construction in India, a country simultaneously confronting widespread underdevelopment and an energy matrix overwhelmingly reliant on carbon-based sources. Our multi-method analysis includes: innovative ArcGIS techniques to create an original database of large hydroelectric projects, field research, and a longitudinal analysis of three distinct periods of dam construction. We find the Indian government gradually shifted from large, multipurpose impoundment dams to smaller run-of-the-river (ROR) projects. ROR dams maintain a smaller footprint by requiring less flooding, but they are less efficient and versatile. Facing greater constitutional protections, concerns about resettlement costs, and past social mobilization, the Indian government is prioritizing smaller projects in remote locations to mitigate the social consequences of dam projects. Nevertheless, environmental concerns have been perfunctory. No fish ladders, exposed riverbeds, compromised waterflow regimes, and minimal riparian rehabilitation mean the environmental consequences of ROR dams remain extremely severe. These findings can be attributed to bureaucratic hierarchies, which limit the power of environmental agencies. Additionally, EIAs have been largely cursory and public audiences have not tangibly improved environmental outcomes because civil society generally prioritizes the social impacts of projects. In conclusion, our study finds India is better reconciling economic development with greater social protection and inclusion. The continued negative environmental externalities of contemporary hydroelectric projects highlight significant space for improving environmental protection.

Impact of climate variability on hydropower generation in an un-gauged catchment: Erathna run-of-the-river hydropower plant, Sri Lanka

Impact of climate change or climate variability on water resources is an exceedingly concerned issue. Hydropower development is one of the most affected industries due to the climatic variability. Therefore, this paper presents the promising results from a study of the impact of climate variability on hydropower generation of Erathna run-of-the-river (ROR) hydropower plant located in Rathnapura district, Sri Lanka. This study was based on surrounded rain gauges outside the catchment as Erathna catchment area is an un-gauged catchment. 30-year rainfall trend analysis from 1988 to 2017 was done using Mann–Kendall and Sen’s slope estimator tests to predict the available trends. Pearson’s correlation coefficient was used to investigate the relationship between rainfall and Erathna power generation. Results show negative trends for annual rainfalls in several rain gauges, while seasonal trend analyses support that observation. July is the most critical month for most of the rain gauges around the catchment. The results also show a good correlation between the rainfalls and power generation. Therefore, the results conclude the importance of rainfall trend analysis in un-gauged catchments and its forecasting capacity of water resources usage in hydropower development.

A toolbox for the optimal design of run-of-river hydropower plants

Hydroelectric power is a relatively cheap, reliable, sustainable, and renewable source of energy that can be generated without toxic waste and considerably lower emissions of greenhouse gases than fossil fuel energy plants. Conventional hydroelectric plants produce energy by the controlled release of dammed reservoir water to one or more turbines via a penstock. The kinetic energy of the falling water produces a rotational motion of the turbine shaft and this mechanical energy is converted into electricity via a power generator. Dam-based plants are among the largest and most flexible power producing facilities in the world, yet their construction and operation is costly and can damage and disrupt upstream and downstream ecosystems and have catastrophic effects on downriver settlements and infrastructure. Run-of-the-river (RoR) hydroelectric stations are an attractive and environmentally friendly alternative to dam-based facilities. These plants divert water from a flowing river to a turbine and do not require the formation of a reservoir. Despite their minimal impact on the surrounding environment and communities, the potential of RoR plants has not been fully explored and exploited. For example, in the United States it is estimated that RoR plants could annually produce 60,000 MW, or about 13% of the total electricity consumption in 2016. Here, we introduce a numerical model, called HYdroPowER or HYPER, which uses a daily time step to simulate the technical performance, energy production, maintenance and operational costs, and economic profit of a RoR plant in response to a suite of different design and construction variables and record of river flows. The model is coded in MATLAB and includes a built-in evolutionary algorithm that enables the user to maximize the RoR plant's power production or net economic profit by optimizing (among others) the penstock diameter, and the type (Kaplan, Francis, Pelton and Crossflow) design flow, and configuration (single/parallel) of the turbine system. Unlike other published models, this module of HYPER carefully considers each turbine's design flow, admissible suction head, specific and rotational speed in evaluating the technical performance, cost and economic profit of a RoR plant. Two case studies illustrate the power and practical applicability of HYPER. Some of their results confirm earlier literature findings, that (I) the optimum capacity and design flow of a RoR plant is controlled by the river's flow duration curve, (II) a highly variable turbine inflow compromises energy production, and (III) a side-by-side dual turbine system enhances considerably the range of workable flows, operational flexibility and energy production of a RoR plant. HYPER includes a GUI and is available upon request from the authors.

Assessment of irrigation shortfall using WATHNET in the Otago region of New Zealand

Knowledge of the likely rainfall and river flow for a coming season can improve management of an overall water resources system without unduly compromising either the environmental or productive behaviour of the system. The objective of this study has been to assess the probability of irrigation demand shortfalls, i.e. soil moisture deficits, for a typical “run of the river” irrigation scheme so as to identify the duration and severity of potential shortfalls. In this study a multi-objective linear programming tool WATHNET has been used to build and run a model of the irrigation scheme. The focus of this study has been on how to use predictions of 3-monthly rainfall and temperature to estimate potential daily water available for irrigation. The method uses Monte-Carlo simulations, to produce multiple replicates of equally likely sequences of river flows, rainfall and potential evaporation values. A sub-set of the equally likely sequences is then selected using prediction information of the likely seasonal climate outlook from NIWA’s Climate Update. The selected sequences, which are biased towards the seasonal climate prediction, are then used as inputs to multiple model runs. By using the output from all the “biased” model runs a probability distribution can be made of water availability for irrigation. The methodology has been demonstrated using the Shag River Irrigation Scheme located in the Otago region of New Zealand. The results compare the predicted soil moisture variation over two three-month periods with retrospective simulations based on the observed rainfalls, river flows and potential evaporation values. Results suggest that WATHNET can simulate 3-month soil moisture dynamics. In order to develop WATHNET as a tool to assess probabilities of irrigation shortfall it needs to be validated using measurements of soil moisture variations over an irrigation season at sites with different soil types.

Well-Being Approach of a Power System Containing Run-of the-River Power Plants

Well-Being Approach of a Power System Containing Run-of the-River Power Plants

Feasibility of Micro-Hydro Schemes in South Glamorgan, Wales

Run-of–the-River Hydro electricity generation, utilizes the natural flow of the river, extracting water from a high point, where it flows to a micro turbine generator, and the kinetic energy is captured. In general, the Run-of-the-River systems have an installed capacity of between <100kW to 5MW, with an efficiency of over 80%, and it remains one of the cheapest forms of renewable energy. Cardiff is the Capital City of Wales and is the tenth largest city in the UK with a population of around 357,000 people as of 2017. Wales currently generates 9% of electricity from renewables with the Welsh government strongly behind a low carbon economy. The city of Cardiff has set a goal to be a ‘One Planet City’ by 2050, which entails reducing the consumption of natural resources and reducing the carbon produced. The objective of Cardiff City is to reduce CO2 by 26% by 2020 by increasing the renewable energy generated around the city and considering the annual rainfall is abundant, with over between 200 - >500mm per year, there is much potential for small scale hydroelectric schemes. One current example of a renewable energy scheme in Cardiff is the Radyr Weir Hydro Scheme which uses water from the River Taff to generate electricity. The gross head of the system has been calculated as 3.5m with a mean flow of 21.37m3/s. The turbines chosen for such a project were two Archimedes screw turbines (3.5 meters in diameter and 10 meters in length) to generate a maximum of 394kW (2 x 200kW). The annual energy yield will be approximately 1.8 million kWh per year, with an annual CO2 saving of around 785 tonnes. Within the Cardiff area, ten more weirs have been identified and the flow velocities measured, and these are located on the River Taff, the Ely and the Rhymney River as well as within small streams such as Roath Brook or abandoned reservoirs such as Llanishen. Three ideal sites have been recognised primarily based on the height of the weir, the site location and the return on investment and these are Llandaff, Pontypridd and Roath weirs, where it is believed there would be minimal environmental impact and sufficient energy could be produced. Blackweir has been discounted even though it is one of the largest, due to the location being a site of scientific interest. Smaller weirs, such as Hawthorn and Upper Pontypridd, with <1.5m in weir height (head) obviously produce much less power, but because of the higher Feed-in-Tariff for pico hydro schemes, they prove to be a much more attractive investment opportunity in contrast to the higher costing bigger projects. However fluctuating Feed-in-Tariffs, which change every 3 months lead to investment uncertainty and it is believed hinders future project development.

Methane dynamics downstream of a temperate run‐of‐the‐river reservoir

AbstractDams impact a significant portion of the world's rivers, and rivers downstream of the reservoirs created by large dams often emit significant amounts of methane (CH4). River CH4 emissions downstream of run‐of‐the‐river (ROR) dams are less well known. We investigated spatial and seasonal CH4 dynamics along a stretch of the Aare River (Switzerland) downstream from a bubbling ROR reservoir. We found that the CH4 horizontally accumulated in this vertically non‐stratifying ROR reservoir was consistently transported to the downstream river, but half was lost near a confluence with a tributary. We estimated CH4 diffusion using gas exchange coefficient (k) models that incorporate specific river characteristics and found CH4 emissions were threefold higher upstream of the confluence than downstream. We discuss the use of CO2‐derived k models in estimating k for CH4, and investigated it directly using a drifting chamber experiment. While chamber emissions only partly agreed with the k models, the models were robust enough to use in a CH4 mass balance along the river that indicated an overall CH4 loss from the study area. The loss predominantly occurred at the confluence and &gt; 92% of it could not be accounted for by modelled or measured CH4 emissions. Ultimately, a ROR reservoir that does not form an anoxic, CH4‐rich hypolimnion enhanced downstream river CH4 emissions, but to a lesser extent than other systems (∼9% of total reservoir‐associated emissions). Regardless, small ROR dams and river features such as confluences should be considered when measuring, estimating or upscaling river CH4 emissions.

Recovery of flow conditions for optimum electricity generation through micro hydro turbines

Generation of electricity from existing canals through micro projects have become practical and alternate solution to large scale hydro projects. Run-of-the-River (ROR) is a hydroelectric generation scheme with limited or no water storage requirements, as the turbines use kinetic energy of flowing water streams, canals, or rivers for power generation. In this research, a micro hydropower generation system has been studied for its utilization in existing canal of Pakistan. The work comprises verification of operation of selected water turbine in water flow conditions of Pakistan through computational analysis. Ghazi Barotha Canal with concrete bed and flowing round the year flowing is taken as a test case for analysis. The process followed includes the modeling of turbine geometry and CFD (Computation Fluid Dynamics) analysis for validation of flow potential recovery in selected canal. CFD analysis of the turbine geometry with different configurations of debris protectors is carried out to evaluate the optimal recouping of flow properties for maximum electricity generation. Moreover, it also determines whether the flow properties are recovered within the selected distance downstream, which is ten times the turbine length.

Environmental sustainability of run of the river hydropower projects: A study from western Himalayan region of India

Run of the river (RoR) hydropower projects are generally considered more environmentally sustainable as compared to their reservoir based counterparts. Further, impacts of these projects are supposed to be in proportion to their installed capacity. Large numbers of this category of hydropower projects in different size ranges are coming up in Himalayan regions. Un-sustainable construction/operation practices adopted during development and/or running of these projects are posing an environmental threat to this fragile and youngest mountain range of the world. This research paper presents a public perception cum data collection study on the environmental impacts of small and large RoR hydropower projects located in western Himalayan region of India. A structured questionnaire was designed to collect the primary data pertaining to intangible impacts while secondary data was collected to analyse tangible environmental parameters. The study concludes that every environmental impact of SHPs is not 'small' as compared to LHPs. Ignoring the environmental impacts of SHPs may not be a good practice.