Placement of Concrete in Hydropower Structures According To Climatic Conditions in Albania

Concrete - 100 years ago a new building material and today regarded as indispensable - camejust in time to be used from the very beginning of the hydropower era in the World, aroundthe turn of the century. It soon became the preferred material for construction of dams andpower-houses, although the performance with regard to durability proved to be poor in many cases, giving rise for concern. Most prone to damage were dams at mountain sites, exposed toharsh climatic conditions. The problem was obviously one of lack of know-how in the field of concrete technology. An important factor in mix design is the ratio between water and binder.As long as only binder is cement, the term w/c ratio cannot be misunder-stood. With theincreasing use of pozzolana as binder in addition to the cement, the term w/b ration is now widely used. The term w/c ration as used in literature shall be interpreted to include pozzolana

Investigation of hydraulic regime at middle part of the Loire River in context of floods and low flow events

Significant variability characterizes natural streams in space and time that describe hydraulic regime of the entire stream. In this paper, the importance of investigation and assessment of hydraulic system in the context of management of surface water resources is discussed. The objective of this study is to investigate hydraulic regime in the middle part of Loire River located in France. Loire River basin is the largest river basin in France and origin of many potential flood events. Investigation of a hydraulic regime of the Loire River is conducted using traditional hydraulic simulation model HEC-RAS. Hydraulic modeling of the river is carried out by considering two different datasets (i.e. flood and low flow events). A certain number of hydraulic structures, which have the significant effect on the hydraulic regime of the river, is considered as well. Through Froude number computation, it is noticed that middle part of the Loire River demonstrates subcritical regime. Accurate calibration and validation of the model are performed by changing Manning coefficient along the riverbed. Computation carried out for both data sets; show that there are no big differences between observed and simulated water levels, results obtained are satisfactory. Therefore, to get more accurate information about the hydraulic regime at the middle part at of Loire River, the further simulation needs to be done by considering an additional dataset of floods and low flow events

Risk assessment from floodings in the rivers of Albania

Flooding is a natural phenomenon in Albania. The floods are flashy and flood - waters occupy the flood plain; in the biggest rivers, close to the river mouth area, these waters inundate the flood plain for several weeks.Attempts have been made to alleviate flood situation in Albania by building protective dykes and creating upstream storage. Although many of these measures have been beneficial, they also served toencourage further encroachment upon river floodplains, thereby raising the potential for flood damage.Actually, more than half of the Albanian population lives very close to the rivermouth areas, where the riskof flooding is higher. The structural solution is only a partial one; the only long - term solution consists ofkeeping flood-vulnerable development and uses out of the flood plain. In order to evaluate the flood potential,a statistical study in national scale was carried out. The peak discharges for different return periods are computed using statistical method and a map of the flood potential for the country is designed. Those constructions had a relevant protective role during the flooding of the winter 1970-71. Non structural measures consist of measures undertaken for flood warning or flood forecasting or different studies likeflood-mapping, estimation of inundation risk and inundation zones and possible damages etc

Geotechnical Analysis of Hill’s Slopes Areas in Heritage Town of Berati, Albania

In this paper are treated briefly the geotechnical analysis of hills slopes areas in the heritage town of Berati, Albania. From engineering geological mapping on scale 1:10 000 and geotechnical investigations carried out in urban area of Berati town was found that two zones are threated from landslides phenomenon. The first one is located in center part, whereas the second in northeast part of Berati urban area. Mass movements occurred in the studied area are present in rocks topple, rocks fall and earth slide types. Rock falls and topple occur on steep slopes of fractured lime-stone rock, whereas the earth slides are found on medium-steep slopes that are built from soils and weathered flysch rocks. From mass movements occurrences many buildings and urban roads are demolished, thus endangering human life. In these conditions a detailed engineering geological study was undertaken to determine landslide distributions and recognize the stable and unstable areas. Also, based on these studies suggestions and recommendations are given for urban development and remedial measures

Assessment of Sediment Transport in the Devolli River

Devolli river is one of the biggest rivers of Albania which is characterized by large stream flow but also during the full stream flow it bring a lot of sediments and this paper consists precisely to calculation rough of sediments transport of this river.It is important to recognizethat present conditions in the Devoll valley are not necessarily the original natural conditions.Deforestation has been reported to be a major problem in Albania (e.g. and based on personalcommunication with stakeholders in the Prespa and Skadar regions, cf. The erosion woundsmay be caused by years of cutting down trees for firewood. If so, then hydropowerdevelopment may assist in reducing the present high erosion rates in this country by reducingthe pressure on trees for firewood, although long time is probably needed before stable hillslopes can be established. However, there may also be other reasons for loss of vegetation thathydropower will probably not assist in reducing: Shuka et al. (2008) referred to degradation oforiginal vegetation cover in the Albanian parts of the catchment area of Lake Prespa, and suggested that the main causes were traditional farming of livestock, uncontrolled grazing andfires. Clearly, the variations are very high. Variations are higher after May 1st than before this date; this may be due to the steady high water discharges in the beginning of the year, whichwill give less variation in loads (cf lower panel). It should be noted that a single high concentration will have a major impact on the calculated total load transport, especially if the water discharge is also high at the same time

Investigation of Average Shear Stress in Natural Stream

Average shear stress is an important parameter for prediction of sediment transport,bank protection and other river engineering problems in natural streams. For this purposevelocity measurements were taken on Kızılırmak River sub branch, named Sarimsakli streamand Barsama station in center of Turkey. Acoustic Doppler Velocimeter (ADV) was used forthis purpose at six different periods and flow conditions. Nikuradse's equivalent sandroughnesses (ks) for each vertical along the wetted perimeter were determined using measuredvelocity distributions. Shear velocity (u*) and shear stress (meas) were determined thenaverage values were calculated for each flow condition. The commonly used one-dimensionalmean boundary shear stress equation at cross-section was re-arranged according to entropyparameter M and it reflects the real flow condition in natural stream

Assessment of riverbank filtration performance for climatic change and a growing population

Riverbank filtration (RBF) consists of green drinking water production in many regions and is used as a pre-treatment phase. This study investigates the performance of the RBF in the Nile delta, Egypt, for climate change and population growth scenarios of 2030, 2040, and 2050. This study presents a new method for predicting the sharing of riverbanks considering three cases: i) the river stage controlling the water levels in the river, ii) increasing RBF pumping, and iii) changing the groundwater levels. This last scenario is achieved by changing the general head in the MODFLOW model. The results showed that RBF sharing (RBFS) is a proportion of the river leakage inflow, in which the decrease of the river stage due to the influence of climate change reduced the river leakage inflow and RBFS. In addition, increasing RBF pumping, decreasing RBF pumping, and lowering the groundwater levels due to the increase in the future drinking water pumping for the population growth increased the river leakage inflow and RBFS. Finally, combining the three cases decreased RBFS in the coming years of 2030, 2040, and 2050, respectively, due to more groundwater sharing than the river inflow. The results show that the water budget is a good tool to investigate RBFS compared with MT3D results. This technique can reduce the cost of water quality collection and analysis; moreover, it will help with the estimation of RBF and save time compared with solute transport modeling

Investigation of seepage effect on river dike’s stability under steady state and transient conditions

World experiences reveal that catastrophic floods are posing a serious threat that comes not only from them as extreme events but also as the result of adaptation measures uncertainty, (i.e. dikes). In particularly old dikes constructed earliest at the north part of Albania, during the last floods demonstrated the high uncertainty and weak spots. In this paper, the significance of the seepage investigation and stability analysis are discussed. As a case study, parts of new dikes constructed last years along the Buna River located in north part of Albania are investigated. Filling materials for these dikes are represented mostly from silt and clay. Finite element method is used to perform seepage analysis while general limit equilibrium method is used to perform slope stability analysis. Both, seepage and slope stability analyses are done for three different scenarios: steady state, rapid filling, and rapid drawdown. Finally, it is concluded that silt-clay material used in these dike structure is posing serious uncertainty during seepage phenomenon by threatening the stability of entire dike structure especially during the transient condition (rapid filling and drawdown)

Comparison and Validation of Hydrological E-Flow Methods through Hydrodynamic Modelling

Flow regime determines physical habitat conditions and local biotic configuration. The development of environmental flow guidelines to support the river integrity is becoming a major concern in water resources management. In this study, we analysed two sites located in southern part of Portugal, respectively at Odelouca and Ocreza Rivers, characterised by the Mediterranean climate. Both rivers are almost in pristine condition, not regulated by dams or other diversion construction. This study presents an analysis of the effect on fish habitat suitability by the implementation of different hydrological e-flow methods. To conduct this study we employed certain hydrological e-flow methods recommended by the European Small Hydropower Association (ESHA). River hydrology assessment was based on approximately 30 years of mean daily flow data, provided by the Portuguese Water Information System (SNIRH). The biological data, bathymetry, physical and hydraulic features, and the Habitat Suitability Index for fish species were collected from extensive field works. We followed the Instream Flow Incremental Methodology (IFIM) to assess the flow-habitat relationship taking into account the habitat suitability of different instream flow releases. Initially, we analysed fish habitat suitability based on natural conditions, and we used it as reference condition for other scenarios considering the chosen hydrological e-flow methods. We accomplished the habitat modelling through hydrodynamic analysis by using River-2D model. The same methodology was applied to each scenario by considering as input the e-flows obtained from each of the hydrological method employed in this study. This contribution shows the significance of ecohydrological studies in establishing a foundation for water resources management actions