Search Results (11)

In many countries, the advancement of hydropower resources has been hindered by economic factors and insufficient data on topography, streamflow, environmental sensitivity, power grid, and, most importantly, the location of potential hydropower sites. This challenge is particularly pronounced in certain African and Latin American river systems. Developing web-based maps of hydropower resources based on geographic information systems and advanced mapping technologies can facilitate the initial assessment of hydropower sites. This is especially relevant for developing sites in remote areas and data-scarce regions. The available geospatial datasets, remote sensing technologies, and advanced GIS modelling techniques can be used to identify potential hydropower sites and assess their preliminary characteristics. This paper reviews web-based hydropower atlases in African and Latin American countries. Their main features are represented and compared with the recently launched HYPOSO map viewer covering two African countries (Cameroon and Uganda) and three Latin American countries (Bolivia, Colombia, and Ecuador). This hydropower atlas consists of 20 spatial layers. Its particular focus is to present a geospatial dataset of new hydropower sites with concise information for potential investors. These so-called virtual hydropower atlases can be only one type of discovery at the early project stage, automatically identifying sites worthy of further investigation. A formal validation of the web-based atlases, including the HYPOSO hydropower atlas, is briefly considered. Creating open-access hydropower map viewers is anticipated to significantly enhance the hydropower development database in these nations, offering valuable insights for small and medium-scale projects. Full article

This article is based on the freely available data of the web-based hydropower map HYPOSO, which the authors compiled. Only the Ugandan river network and associated hydropower potential are highlighted here, using freely available geospatial datasets. The main objective was to assess Ugandan river and stream hydropower potential, compare it with previous assessments, and identify potential sites for small hydropower plant installation. GIS techniques were extensively used to analyse hydrological and other related geospatial data. The stream-reach power potential was determined based on channel slope, the length between tributaries, and the average flow derived from a specific runoff distribution map. Stream profiles extracted from the river network’s digital elevation model were validated against previous assessments. Uganda’s hydropower potential was determined in various patterns, and its values were compared with prior estimates. Around 500 potential high-energy intensity stream reaches and new potential areas for small hydropower plant development were identified in this country, considering a range of characteristics. Statistical datasets were analysed, and their straightforward summaries were presented. These summary characteristics of hydropower potential are necessary for decision-makers to foster hydropower development in this country. Full article

This paper presents research concerning dewatered areas in the littoral zones of the Kaunas hydropower plant (HPP) reservoir in Lithuania. It is a multipurpose reservoir that is primarily used by two large hydropower plants for power generation. As a result of the peaking operation regime of the Kaunas HPP, the large quantity of water that is subtracted and released into the reservoir by the Kruonis pumped storage hydropower plant (PSP), and the reservoir morphology, i.e., the shallow, gently sloping littoral zone, significant dewatered areas can appear during drawdown operations. This is especially dangerous during the fish spawning period. Therefore, reservoir operation rules are in force that limit the operation of HPPs and secure other reservoir stakeholder needs. There is a lack of knowledge concerning fish spawning locations, how they change, and what areas are dewatered at different stages of HPP operation. This knowledge is crucial for decision-making and efficient reservoir storage management in order to simultaneously increase power generation and protect the environment. Current assessments of the spawning sites are mostly based on studies that were carried out in the 1990s. Surveying fish spawning sites is typically a difficult task that is usually carried out by performing manual bathymetric measurements due to the limitations of sonar in such conditions. A detailed survey of a small (approximately 5 ha) area containing several potential spawning sites was carried out using Unmanned Aerial Vehicles (UAV) equipped with multispectral and conventional RGB cameras. The captured images were processed using photogrammetry and analyzed using various techniques, including machine learning. In order to highlight water and track changes, various indices were calculated and assessed, such as the Normalized Difference Water Index (NDWI), Normalized Difference Vegetation Index (NDVI), Visible Atmospherically Resistant Index (VARI), and Normalized Green-Red Difference Index (NGRDI). High-resolution multispectral images were used to analyze the spectral footprint of aquatic macrophytes, and the possibility of using the results of this study to identify and map potential spawning sites over the entire reservoir (approximately 63.5 km²) was evaluated. The aim of the study was to investigate and implement modern surveying techniques to improve usage of reservoir storage during hydropower plant drawdown operations. The experimental results show that thresholding of the NGRDI and supervised classification of the NDWI were the best-performing methods for the shoreline detection in the fish spawning sites. Full article

This paper presents research on the dewatering areas during drawdown operations in the Kaunas Hydropower Plant (HPP) reservoir situated in the lowland area of Lithuania. It is a multipurpose reservoir primarily used for power generation by two large hydropower plants. Because of the HPP peaking operation and the reservoir morphology—a shallow, gently sloping littoral zone—significant dewatered areas can occur (during drawdown operations). This is especially dangerous during the fish spawning period. Therefore, reservoir operation rules are in force that limit operation of the HPPs and secure other reservoir stakeholder needs. There is a lack of knowledge about the fish spawning locations, how they are changing, and what areas are dewatered at different stages of HPP operation. This knowledge is crucial for decision making and efficient water resources management in order to increase power generation and protect the environment at the same time. A detailed survey of an area containing several potential spawning grounds (about 5 ha) was conducted to track changes in the dewatering areas. The aim of the study is to investigate different surveying methods, gather knowledge about potential fish spawning sites, and investigate the dewatered areas that occur during water level (WL) fluctuations. The methodology and insights of this study can be used in similar lowland countries to assist in improving the usage of water resources while increasing power generation. Full article

This paper focuses on possible power generation by micro-hydro turbines integrated into lowland wastewater systems, which convert the potential energy of effluents in pipes into electric power. While other European countries have widely invested in this technology, Lithuania and other Baltic countries are still behind with their potential development rate. A search for potential micro-hydro sites was carried out, and a methodology for assessing water resources for an ungauged wastewater network is proposed herein. Particularities of wastewater flow patterns are briefly reviewed, and turbine operational constraints are analyzed. The hydro turbines available on the market to be installed in wastewater systems that meet lowland conditions are discussed. Available tools on the hydropower market to conduct a preliminary assessment of potential sites for urban water networks are considered. Multicriteria analysis is performed to select optimal projects by assessing the relevant economic, technical, and environmental criteria in water networks. The outcomes of this study can be used for unlocking the hydropower potential of wastewater systems in low-lying areas. Full article

The impact of regional climate change on the runoff and the regime of glacier- and snow-fed rivers in the transboundary river Shu basin between Kazakhstan and Kyrgyzstan is investigated. This study covered three of the most representative rivers of the Shu basin. It was based on the weather and gauging stations’ observation data in the river Shu basin — the northern Tien Shan. Based on the trend analysis, an increase in the average annual temperature and river discharge was identified within the observation period as a whole, and for the separate compared periods. Furthermore, the mean annual flow projections were made based on the methodology of the retrospective analysis of runoff and the rate of river flow increase for the observation period, and further extrapolation of data for the forecast period. According to the analysis, the mean annual flow for the considered rivers will be decreased by 25 to 30% on average by 2050. These findings are necessary for elaborating adaptation measures in water allocation for freshwater supply, irrigation and hydropower within this transboundary river. Full article

Hydropower plants produce renewable and sustainable energy but affect the river’s physico-chemical characteristics and change the abundance and composition of the aquatic organisms. The impact of large HPPs on the ecological conditions of surface water bodies have been extensively studied, but less attention has been paid to environmental impact studies of small hydropower plants (SHPs). The impact of hydropeaking on both the river flow regime and ecosystems has been well-studied for peaking mode plants, mainly medium to large-sized ones. However, for small hydroelectric power plants, and especially for those in lowland rivers, the available information on water quality, benthic macroinvertebrates communities and fish abundance, and biomass is not sufficient. Ten small hydropower plants were selected, and the ecological status of water bodies was assessed in different parts of Lithuania. The studies were performed at the riverbed upstream from the SHPs, where the hydrological regime has not changed, and downstream from the SHPs. It was found that the small hydropower plants do not affect the physico-chemical values of the water quality indicators. This study demonstrated that the total number of benthic macroinvertebrates taxa (TS) is influenced by the concentration of nitrogen and suspended solids, the water flow, the river area, and the current speed; the number of EPT (Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies)) taxa is influenced by the concentration of nitrogen and suspended solids. The studied indicators do not have a significant impact on biomass. The SHPs affect the fish abundance and biomass. The Lithuanian fish index (LFI) is influenced by the average depth and area of the river. Some SHPs operating in lowland areas may yield somewhat significant hydrograph ramping but more detailed investigation is needed to support the significance of this impact on the biological indices. Full article

Small hydropower (SHP) plays an important role in the Baltic States as a reliable and efficient source of electricity from renewable sources. This study presents the historical development, current status, and possible trends for the future development of SHP in the Baltic States with insights into the legal background and development policies for SHP in Estonia, Latvia and Lithuania. For the assessment of hydraulic structures in the Baltic States, the historical data was used supplemented with data from hydropower associations, the national departments of statistics, electricity transmission systems operators, etc. The currently recommended best practice for SHP development is the utilisation of existing sites with available infrastructure. These include old water mill sites and existing dam sites, which, in the Baltic States, number more than 1500. The majority of these sites have their power potential attributed to micro-hydro (<100 kW). In this study the potential of the hydropower capacity at historic, currently nonpowered dams is evaluated and the distribution of the micro-hydro sites within the EU network of protected areas under Natura 2000 and nationally designated areas is presented. The potential electricity generation from such historic sites in the Baltic States is more than 200 GWh/year. Full article

This paper discusses rapid flow and stage fluctuations in a large lowland river downstream from a large hydropower plant (HPP) in Lithuania. The main problem arises when the HPP is operating in peak mode. Such operation of HPP causes rapid flow and stage fluctuations, which can have a certain impact on river ecosystems. The study analyzes general abiotic indicators such as upramping and downramping rates and stage fluctuations downstream of the HPP. The main idea was to assess recorded stage upramping and downramping rates along the river downstream of large HPP. To assess stage fluctuation statistics, COSH software was used. A maximum upramping rate of 1.04 m/h and maximum downramping rate of 0.88 m/h were identified using data from temporary and permanent gauging stations. Obtained results revealed that stage fluctuations exceed ecologically acceptable rates up to 20 km downstream of HPP. The effect of hydropeaking fades out only at a chainage of 45 km downstream of HPP. In mountainous regions, ecologically acceptable rates are reached at much smaller distances. The study shows that the traditional coefficient of variation of stage fluctuation data can be used to describe hydropeaking indicators. The main results of this study can be used for environmental impact assessment downstream from HPPs. Full article

This article discusses the environmental issues facing small hydropower plants (SHPs) operating in temperate lowland rivers of Lithuania. The research subjects are two medium head reservoir type hydro schemes considered within a context of the global fleet of SHPs in the country. This research considers general abiotic indicators (flow, level, water retention time in the reservoirs) of the stream that may affect the aquatic systems. The main idea was to test whether the hydrologic regime has been altered by small hydropower dams. The analysis of changes in abiotic indicators is a complex process, including both pre- and post-reservoir construction and post commissioning of the SHPs under operation. Downstream hydrograph (flow and stage) ramping is also an issue for operating SHPs that can result in temporary rapid changes in flow and consequently negatively impact aquatic resources. This ramping has been quantitatively evaluated. To avoid the risk of excessive flow ramping, the types of turbines available were evaluated and the most suitable types for the natural river flow regime were identified. The results of this study are to allow for new hydro schemes or upgrades to use water resources in a more sustainable way. Full article

This paper reviews and compares software tools for the planning and design of small hydropower (SHP) plants. The main emphasis is on small scale hydropower resource assessment computer tools and methodologies for the development of SHP plants corresponding to a preliminary or prefeasibility study level. The paper presents a brief evaluation of the historic software tools and the current tools used in the small hydro industry. The reviewed tools vary from simple initial estimates to quite sophisticated software. The integration of assessment tools into Geographic Information System (GIS) environments has led to a leap forward in the strengthening of the evaluation of the power potential of water streams in the case of the spatial variability of different factors affecting stream power. A number of countries (e.g., Canada, Italy, Norway, Scotland and the US) have re-assessed their hydropower capacities based on spatial information of their water stream catchments, developing tools for automated hydro-site identification and deploying GIS-based tools, so-called Atlases, of small-scale hydropower resources on the Internet. However, a reliable assessment of real SHP site feasibility implies some “on the ground” surveying, but this traditional assessment can be greatly facilitated using GIS techniques that involve the spatial variability of catchment characteristics. Full article