1.1 Management Of Reservoirs And Their Environmental Goals
2.1 Estimating Ecosystem Flow Requirements
2.2 The Role Of Water Evaluation In Addressing Global Environmental Flow Requirements (Efrs)
3 MAJOR EFFECTS AND CONSEQUENCES OF BUILDING LARGE DAMS AND RESERVOIRS
3.1 Laws And Regulations For Reserviors
3.2 How Reservoirs Are Controlled Or Regulated
4 DESILTING RESERVOIRS
4.1 Identifying Incompatibilities Between Human And Ecosystem Needs
6.1 Internet Sources
Reservoirs have since been the earliest civilisation, being part of man kind strategy for survival. These water storage facilities have been created since time immemorial mainly by constructing dams accross rivers and are intended both for capturing water that would otherwise proceed down river towards the oceans or lakes as well as for storing the water for as long as possible, till when needed and used. Sediments which is naturaly released from the catchment areas into the reservoir via contributing stream is impeded by the water bodies in the reservoir which are retained by the dams and to a large extent the sediments is permanently trapped there in. This paper talks about managing the flow of reservoirs and regulated river or dam and how to improve its sustainability by balancing the needs of the society, the economy, the environment and the ecosystems. Likewise its environmental goals, its role on a global scale with the laws and regulations guiding it are also discussed in this paper .
Keywords: dams, ecology, flow , reservoir, water
Water is the most essential of our natural resources, and it is the responsibility of every consumer to ensure that we manage and use it effectively and sustainably. The latest climate change predictions show that pressure on water resources is likely to increase in the future. In light of this, we have to ensure that we continue to maintain and improve sustainable thoughts by balancing the needs of society, the economy and the environment. The natural flow patterns of rivers and creeks can be disrupted by human activity, for example:
People and businesses using river water, dams built to provide drinking water, land being built on, changing the way water runs off surfaces and into rivers and Pumping groundwater found beneath the earth's surface, often between saturated soil and rock crevices – this reduces the amount of water that would otherwise flow into rivers and wetlands. Reservoir is an outdoor storage area whereby water is amassed and preserved in quantity in order that it should be drawn off for use. Generally, reservoirs are designed by constructing dams across rivers. However, off-channel reservoirs may be provided by redirecting canals and pipelines that carry water from a river to natural or artificial depressions At that point when stream flow is seized in a reservoir, there is reduction in velocity flow and silt is deposited. Therefore, streams that convey much suspended sediment are poor locations for reservoirs. Sedimentation deposits will quickly reduce and diminish storage capacity and greatly shorten the useful life of a reservoir that is small. For larger reservoirs however, siltation constitutes a serious problem because is generally very costly and difficult to remove sediments deposited in reservoirs making the life expectancy of most reservoirs not more than a 100 years. This paper talks about managing the flow of reservoirs and regulated river or dam and how to improve its sustainability, its effect ,its role on a global scale with the laws and regulations guiding it.
Water reservoirs range in different sizes and is multifaceted in nature whereby its complexity ranges from little single-criterion issues to complex multiple-purpose problems. For example a single-purpose reservoir is constructed to achieve only one purpose, such as navigation, flood control, water supply, recreation, irrigation and power generation. Work is still going on in the construction of multiple-purpose reservoirs with the intent of serving at least two major functions. Reservoirs or regulated rivers are two types of close aquatic ecosystems with a typical source or starting point which have a unidirectional association or relationship. One cannot exist without the other and both rise up out of necessity to exploit and take advantage of water resources. Everything that happens inside the reservoir affects the regulated river downstream. In the developed world, social insight especially urban perception take more cognizance of the negative environmental impacts of reservoirs and ignores underestimate and does not value or take cognizance of its positive effects. Because of this, regulated or controlled rivers are frequently subjected to very low flow rates, and mostly appear to be a degraded fluvial ecosystems.
Considering this action , there are some individuals who cast blames on the reservoirs for the tremendous damage sustained by the rivers, and they are actually asking for the demolition and annihilation of dams for different selfish reasons (Poff& Hart,2002; Brufao, 2002), while others value, esteem and regard the involvement and commitment of this kind of artificial ecosystem to modern day welfare due to the control of the available water and energy in time and space because of the existence of reservoirs and regulated rivers (Bergaet al.,2002). Environmental flows are portrayed as the quality and timing of water flows needed to maintain freshwater and estuarine ecosystems and the human well-being that rely on these ecosystems. The past two decades have experienced increased global concern about the need for sustainable water and land management. Water resource availability and use is altered by human growth, economic development, global climate change etc, which leads to increased risk of flow regimes that has been altered, dangers to water quality and water demands which exceeds renewable supply. Water security is mostly achieved with little thought of environmental effects.
Notwithstanding, when they are recognised, the desire for water between humans and the environmental is growing and expanding at an alarming rate. However, the environmental flows concept has kept on developing and growing despite all the difficulties and challenges its facing. Transferability of experience on the field is very limited and in adequate and this is due to the dominance of specific case-study analyses and little or no research on how to govern environmental flows. To implement the environmental flows concept, dialogue needs to be done amongst scientists, researchers, policy-makers, water managers and the indigenes concerning sustainable water utilization. Scientific and Social projection seasoned by earth science have considerably added to the progress of reservoirs and controlled or regulated rivers which encourages and urges solutions rather than theories in the face of sensible and practical water management issues. Reservoirs are superb systems for experimenting and confirming virtually any ecological ideal model (Ward& Stanford, 1984; Straskrabaet al., 1993). It is unquestionably genuine and true that there are badly designed or unnecessarily built reservoirs, and there are doubtlessly taken advantage of, criticizing the situation is inherent, however it may also be viewed as an inherited situation which can and should be improved using environmental management principles.
1.1 Management Of Reservoirs And Their Environmental Goals
Of all the environmental changes and adjustments created by dam development and reservoir operations, the alterations of natural water flow regimes has had the most prevalent and damaging results on the river ecosystems (Poff et al. 1997, Postel and Richter 2003). Related problems of reservoirs is erosion of the stream channel beneath a reservoir when water is released or discharged. Since the sediment or dreg load is deposited within the reservoir, the discharged water has improved transporting capability and channel erosion effects. . The role of water-storage reservoirs, however, is to seize and stop the flow of water in periods of higher flows so as to avoid flooding and allow gradual but steady release of water during periods of lower flows. Reservoirs and regulated rivers started way back in human history primarily to provide and make available water for drinking and for irrigation purposes. The use of reservoirs spread from southern Asia and northern Africa to Europe and the other continents of the world. At that point when stream flow is seized in a reservoir, there is reduction in velocity flow and silt is deposited. Therefore, streams that convey much suspended sediment are poor locations for reservoirs.
Sedimentation deposits will quickly reduce and diminish storage capacity and greatly shorten the useful life of a reservoir that is small. For larger reservoirs however, siltation constitutes a serious problem because is generally very costly and difficult to remove sediments deposited in reservoirs making the life expectancy of most reservoirs not more than a 100 years. The ecological administration of reservoirs must be considered from a global perspective on the conditions that the target area are complete, common and balanced. These objectives are very simple to list but hard to reach. Owing to this, most times when the technical aspects are has been taken care of, some other conditions which include social, economic, and even legal conditions requires more complex, difficult and advanced solutions.
This can be characterized as the excess supply of nutrients in a lake or other body of water, this is due to run-offs from the land and this causes explosive growth of plants and algae in a body of water. A state of hypoxia is reached when organism consume all the oxygen in the body of water resulting to their death.
Eutrophication, the presence of which is more probable are stronger in reservoirs than regulated rivers conditions not minding or taking into considerations their water quality. The two main objectives and goals of eutrophication primarily are to control the level of nutrients that reaches the reservoirs and maximize their processing capacity in the reservoir-regulated river system. The main challenge of environmental sustainable water management is to form, implement and execute a water management program that stores and redirects water for human utilization in a manner that does not influence the ecosystems to degenerate, break down or modify. This journey for parity basically recommends that there is a limit to the quantity of water that can be drawn from a river, and there are also limits in the extent to which the shape of a streams natural flow designs can be changed.
These points of confinement are described by the ecosystem’s needs for water. Human control that surpass these limits of confinement will in time compromise the ecological reliability of the affected ecosystems, which brings about the loss of local species and gainful ecosystem products and services for society which are lucrative .With human employment of water and our understanding of ecosystems frequently evolving, the solutions and answers for meeting both ecosystem and human desires will advance overtime likewise. Furthermore, environmentally sustainable water management is an iterative process associated with both human water demands and ecosystem requirements, refined, and modified to meet human and ecosystem needs concurrently once and for all. Water-related sicknesses are mostly linked with the invention of irrigation which is a product of water flow from a typical reservoir such as a dam. Illnesses that are mostly associated directly with irrigation include malaria, and river blindness whose vectors multiply in the irrigation waters. Other irrigation-related health issues include deterioration of water quality and increased population pressure in the area. The reuse of wastewater for irrigation has the ability, depending on the magnitude of treatment and spreading of communicable diseases.