Abstract Despite the numerous benefits of hydropowerproduction, this renewable energy source can have serious negative consequences on the environment. For example, dams act as barriers for the longitudinal migration of organ- isms and transport of particulate matter. Accelerated siltation processes in the receiving river reduce the vertical connec- tivity between river and groundwater. Hydropeaks, caused by short-term changes in hydropower operation, result in a negative impact on both habitat and organisms, especially during winter months when natural discharge is low and almost constant. In this study, we report the current deficits present in the River Rhone from two different scientific perspectives – fish ecology and hydrology. Potential reha- bilitation solutions in synergy with flood protection mea- sures are discussed. We focus on the effects of hydropeaking in relation to longitudinal and vertical dimensions and dis- cuss local river widening as a potential rehabilitation tool. The fish fauna in the Rhone is characterized by a highly unnatural structure (low diversity, impaired age distribution). A high correlation between fish biomass and monotonous morphology (poor cover availability) was established. Tracer hydrology provided further details about the reduced permeability of the riverbank, revealing a high degree of siltation with K values of about 4.7 × 10 −6 m s −1 .
For further details on the FEST-WB model and its applications, the reader can refer to [ 39 – 44 ]. The calibration of the snow module parameters was performed in a previous study described in [ 45 ]. No other parameters were calibrated as the first assigned values, which were based upon measured values, the reference literature, or an educated guess, provided satisfactory results in terms of the time series discharge simulation. The performance of the model was assessed by comparing the simulated and observed discharge at Candoglia hydrometric station in the period from 2001 to 2010. The year 2000 was treated as the period for the model initialization. The performance of the FEST-WB model was assessed through the goodness of fit indices, the root mean square error (RMSE) and the Nash and Sutcliffe efficiency (η), defined as follows:
The Agbokim community is 23km from Ikom Town and a boarder community between Nigeria and Cameroon. Agbokim Waterfalls is in Etung Local Government area of Cross–River State. Agbokim community and the neighboring communities are connected to the national grid. The small hydro scheme can be a “Grid-tie” or “Off-grid”. The main income of the people is from Agriculture. The crops are cassava, cocoa, and chewing sticks production is also a major source of income. The total population of the Agbokim community and other neighboring communities is about 4,000 (National Population Commission, 2007).
effects on the wild ﬁsh catch from the river system. While it is easy to see that the construction of hydropower dams change river ﬂow, such a connection with food supply is less obvious: changes in food supply alone do not necessarily change river ﬂow for the LMB or any other river basin. Just how is the management of the resource of the LMB river ﬂow linked to the supply of food and how does that supply of food affect river ﬂow? Further stages in this loop are needed to capture the inﬂuences at work. Orr et al. [ 10 ], among others, have shown that the development of hydropower projects changes overall food supplies in the lower Mekong Basin, including increasing demand for land-based agricultural production. Changes in land-based food production entail major changes in water infrastructure and water management, for example, changes from once a year ﬂood recession rice crop to two or even three annual crops using managed irrigation [ 22 ]. Increasing food supply reduces the water resource, driving more investment in water resource management associated with food production. This forms a basic causal loop, or inﬂuence diagram (Figure 4 ) from which the hydropower–food supply nexus in the lower Mekong Basin can be constructed. The effects of this loop on the system and the nature of its feedback, positive or negative, are further explored below. Information from the literature was drawn on to deduce and graph the relationship between variables.
The most important requirement for stream flow estimation methods using the mean annual flows for gauging rivers is that sites must show similar hydrological characteristics. To achieve this requirement this study adopted the L-moment homogeneity analysis approach for regionalization of a homogenous region as described and ex- plained in the book “Regional Frequency Analysis,” . However, there exist additional requirements specifi- cally attached to each flow estimation method and these were also considered in the study.
The treatment of water in general requires two treatment i.e. Primary treatment and Secondary treatment. In which there are multiple units and different processes to be carried out. All this becomes inefficient as well as uneconomical to be carried out in treatment plants due to large volume of the river flow. A new method is introduced by modification of concept of check dams, in which a river channel is divided into different compartments by constructing baffle walls which has opening on the alternate side as well as in top or bottom respectively. The 3-D zig-zag method is important for sedimentation and screening of floating material. This is done by compartments which has top opening on one side (for e.g. Top left opening) and bottom opening on other side (for eg. Bottom right opening) in alternative manner. The top opening helps for settling of sediments and the bottom opening blocks the floating matter. In addition to this method of treatment, Algae based treatment can be provided which helps in increasing of Dissolved oxygen and biological degradation. Microalgae are normally unicellular called as phytoplankton. We cannot see by naked eye due to microscopic in size. If we consider present scenario, microalgae has been in news since last ten years in terms of the capability of producing biofuels as well as treating or polishing municipal and dairy wastewater. Extreme focus to be given on microalgae based treatment.
“... a picturesque image of floating houseboats, fishermen laying their nets, river merchants, natives bathing and enjoying the clear water of the river, and busy ‘lavanderas’ along the banks …(Harper, A River With A Past) Pasig River was once a picture of a healthy river
Ecological studies on ROR hydropower have largely in- vestigated impacts on ﬁ sh, e.g. Kubecka et al. (1997) and Ovidio et al. (2008). However, the hydraulic impact of ROR schemes may have consequences at lower trophic levels, for example affecting benthic macroinvertebrates which have important roles in organic matter processing and are a vital food source for ﬁ sh, riparian insects, birds and mammals (Castella et al., 1995; Covich et al., 1999). Many invertebrate taxa are known to be sensitive to near- bed hydraulic conditions; velocity and turbulence parame- ters in ﬂ uence critical processes such as food acquisition, movement (drift) between habitat patches, substratum con- dition and predator evasion (Hart and Finelli, 1999; Jowett, 2003), whilst also causing entrainment or dislodgement (Hart and Finelli, 1999) and, sometimes, physical damage to taxa (Growns and Davis, 1994). Thus, many invertebrate taxa express streamwise (longitudinal) velocity preferences (Extence et al., 1999) and are known to be vulnerable to hy- draulic changes associated with water abstraction, particu- larly taxa requiring high velocity habitats (Degani et al., 1993), or which have restricted feeding (and thus habitat) re- quirements, e.g. ﬁ lter feeding, net spinning Trichoptera (Jowett, 2000). Invertebrate distributions can also be af- fected by shear stress (Gibbins et al., 2010) and turbulence (Blanckaert et al., 2013), although this is not always the case (Robson et al., 1999), indicating that the response may vary among rivers (Jowett, 2000).
To improve the average velocity, it was decided to modify the structure of the device by inserting a flange at the exit of the divergent. The reason for adding this attachment is to permit an accelerated flow upon exiting the divergent without being hampered by the slower flow encountered on the outside. In fact, a region of low pressure formed by a strong vortex behind the flange attracts a greater mass of fluid toward the throat inside the device. The simulations carried out with SolidWorks confirm the efficacy of the system combined with the ISO 5167-3 geometry. Ohya Y. et al. (2010)  use straight flanges with ℎ ⩾ ∗ . . In any event, in our case we designed an flange tempered by a fitting with a radius equal to its width/ height (symbol S). This proved to be more effective (+ 0.8%). In addition, since the flange is the part of the structure that is most stressed it results in improved advantages of resistance. Table-4 below shows the velocities reached with the help of this type of flange varying the h. As is shown, up to h=0.480 m there is an increase of 6.9% in the average velocity. Afterwards, there are no evident or significant advantages to increasing the height. Figures 12(a) and (b) show the depression effect that the flange, expressly designed for our nozzle, produces at the divergent outlet with respect to the initial geometry ISO 5167. What is more, the parameter S A goes
We have observed in last few years history, we show flood of Bangaon Block is regular events. In past day is not any flood in Bangaon Block, that’s not true. In 1971-72 be effected by big flood. But that’s was parted (separated) event. In the present 2000 years big flood from before few years (1995) and then the present time 2010 every year is flooded separated area in Bangaon Block. But why this change? Why once a time fem Bongaon Block, to day every years flood affected? What is this flood or water logging ? If we do not any deeply discus we not get right answers. In general we know suddenly heavy rainfall, over load water in river bed etc is main cause for river. But is what heavy rainfall in every years in Bongaon Block and that’s main reason for flood in this region? No, that’s not right. Because Rainfall date in Bongaon Block give not that’s answers.
water resources (IPCC, 2013). Hydrologic systems in arid/semi-arid regions are particularly sensitive to climate changes (Chen et al., 2006; Guo et al., 2015), as are highly glaciated regions (Claudia et al., 2012; Huss et al., 2008). Regarding retreating glaciers caused by the warming temperature, a stronger spring and early summer river runoff and a reduced late summer flow have been observed in the most highly glaciated watersheds (Barontini et al., 2009; Bavay et al., 2013; Jeelani et al., 2012; Liu et al., 2009). However, the effects differ substantially from region to region, Su et al. (2016) indicated the earlier and stronger spring runoff may help the irrigation water of Indus Basin in the spring growing seasons. Immerzeel et al. (2010) suggested the effects in the Brahmaputra basins seem likely to face the severer water availability and flood security owing to the high dependence on the irrigated agriculture and the large population but the effect may be positive in Yellow River since the low dependence on melting water and increased upstream precipitation. In addition to stream runoff, evaporation has received some study, and significant increasing trends in response to climate change have been reported (Calanca et al., 2006; Thompson et al., 2014). Moreover, the strong influences on groundwater system in the large-scale agricultural catchment also have been ascertained (Roosmalen et al., 2009). These studies separately focused on one or more water components of hydrological processes under climate change but little attention was paid to the redistribution of water resources in hydrological processes from a water balance perspective.
estimates of abundance (Laake & Borchers 2004). Here, we use the term ‘narrow strip’ to refer to the band up to 300 m from the river margin. Thus, we were able to fit a detection function and assign a detection history using the same observers (reducing perception bias, which strongly depends on ob - servers), instead of using the detection function fitted only to cross-channel transects from different sur- veys (as in Gomez-Salazar et al. 2012a). In addition, another advantage of our approach is the incorpora- tion of covariates in both processes (MR and DS). Besides providing unbiased estimates compared to pooled data (Marques & Buckland 2003), this enables an evaluation of which aspects are more important for the detection of dolphins. Although it was not pos- sible to navigate in the center of the river most of the time because of its large width, we conducted zigzag transects, and thus we are confident that the MRDS model was adequately used in the close-to-the- margin and cross-channel transects.
Integrated management is described as the planning of activities including manage- ment and use of natural resources existence of social, political, economic and institu- tional factors, taking into account for sustainable management and planned of natural resources in the basin . With integrated basin management, conservation and sus- tainable use of the basins, which is effective in all institutions, policies and activities of the authorities and individuals, are given the provision of effective and regular coordi- nation . Hydroelectric production meets 19% of the world’s energy requirements and constitutes one of the major driving forces behind the construction of the 45,000 large dams available in the world . Electricity generation is very small effect on the amount of water (limited losses by evaporation from dams), but the release time of wa- ter for electric production according to demand curve is to change the hydrograph of river flows.
Southern Africa, and the Zambezi River Basin (ZRB) in particular, are bound to face significant challenges related to their water resources in the coming decades. On the one hand growing population and booming economic activity will undoubtedly increase the pressure exerted on natural ecosystems, be it in terms of land use changes, direct water abstractions for irrigation, or increased evaporation from new hydropower schemes. On the other hand, studies indicate that climate change is likely to have a strong impact on the basin’s climate and runoff characteristics (Intergovernmental Panel on Climate Change (IPCC), 2001). Presented what can be classified as worrying figures, Arnell (1999) found that the ZRB can witness decreased precipitation (~15%), increased potential evaporative losses (~15-25%), and diminished runoff (~30-40%).
Moreover, considering environmental and ecological problems, the results indicate the rate of water resources development and utilization must be kept in a reasonable range. The widely accepted rate for reasonable water resources development is about 30% whereas the extreme rate is not higher than 40%. In China, the average rate of water resources development is about 20%; in the southern part it is lower than 20% and in the northern part, much higher than 20%. Among those river systems in North China, the Liaohe River, the Huanghe River and the Haihe-Luanhe river systems all have a devel- opment rate higher than 50% and the Haihe-Luanhe river system reaches a value of 80%. Because of water resources depletion, the phenomena of river channel drying-up, lake shrinkage and everglades disappearing in the Haihe River and the Huanghe River have become more and more serious. In addition, for there is not enough water for decontami- nation, with the increasing sewage discharge into the rivers, the three rivers mentioned above have become the most seriously polluted rivers in China. Drying-up of the channels and pollution of the rivers have made the aquatic species reduce greatly. And in some segments of the rivers, aquatic species are no longer in existence, hence the so-called “the dead rivers”. All these have done great harm to the socio-economic development and to the health of the local people. One of the main reasons for environmental and ecological degradation in North China, especially in the Haihe-Luanhe and the Huanghe river sys- tems, is the excessive utilization of water resources, which is out of proportion to the water required for environment and ecology. It must be noted that environmental and ecological water requirements of the river systems should be obligated in river system planning.
River basins of the Morava river belong to the most manifold, versatile and precious regions in Slovakia. Heterogeneous natural conditions, vivid interactions with neighbouring countries as well as the rather deeply profiled place attachment in the mental representations of inhabitants make this region highly valuable in terms of the research of recent processes of spatial and societal development. Influenced by the immediate vicinity of the river, the highly profiled regional identity of the river basins might be one of the most significant issues in the further spatial development in this border region. The landscape in the hinterland of the river Morava is perceived to be attractive enough to play key role in the process of territorial identification of the participating inhabitants. This was especially visible within the group of middle‑aged generation with higher education. In the situation when there are specific features, e.g. Lednice‑Valtice area (UNESCO cultural heritage, see Fig. 2) or the Devín Castle Rock and Tower (see Figs. 3, 4) as memorable landmarks, this increases the position of the river in the mental maps of people living in the area. For local people of the Moravia region the river Morava is particularly a pleasant and dominant landscape element and a place suitable for leisure time activities.
Nitrogen (NORG), Temperature (T) were tested and modelled in the Jajrood River in north of Tehran province. A one - dimensional mathematical model written by C#2008 programming language with finite difference method and model can be computed hydrodynamic and water quality Parameters in Jajrood River for different reaches. This novel model, which is designed based on a technically robust and highly accurate graphic software, does qualitative calculations at a very short time. It also gives all the information about the occurrences during the dumping of sewage and even determines the highest concentration of sewage allowed to be dumped at the river. The model was calibrated and verified by using qualitative data collected from several stations along the study area form June 2006 to June 2007. The model was tested during different months of the year with satisfactory results. The simulated results of the model are in good agreement with measured values. The model can be useful in guiding engineering and management decision concerned with the efficient utilization of Jajrood River water and the protection of their quality.
3.7 Influence of terrain on 3B42V6 performance The influence of terrain gives rise to the high spatio-temporal variability of rainfall. This is especially true in mountain- ous regions, such as the Jinsha River basin which has alpine and gorge terrains. Therefore, the influence of terrain on the 3B42V6 performance in this investigation area should be considered. Influence factors of the altitude, longitude, lat- itude, slope, and the aspect of each station were usually se- lected to evaluate the geographical factors on the impact of rainfall, and so these were taken into account in this study. Actually, it is an indirect method to validate the variation trends of statistical indices between the two datasets with these geographical factors, which is intended to reflect the performance of 3B42V6 affected by the degree of these fac- tors. It is worth mentioning that the study area has complex terrain and is located in the west of Sichuan Basin, which influenced the systematic climate zone changes. That is why the altitude, longitude and latitude were selected. In addition, although the slope and aspect are local, regime-dependent factors, they were also taken into account just for integrity of analysis. In order to determine the main influence fac- tors on the performance of 3B42V6, the 3B42V6 mean rain- fall (MR), the gauged mean rainfall (MR), the NSE, FBI, and POD on different temporal scales of the two datasets from 107 stations and grids were computed firstly. Then the TCCs between each index and altitude, longitude, latitude, slope and aspect of 107 stations were calculated, as shown in Fig. 13. Compared to the Ccc (0.19 by 95 % significance test level), the factors of slope and aspect were mostly not through the significance test (in red); however, the other in- fluence factors were almost all through the significance test (in blue). Therefore, the terrain elements of altitude, longi- tude and latitude were chosen as major influence factors; and the indices of NSE, FBI, and POD were used for validation.