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environmental flow Assessment of Great Ruaha River in Southwestern Part of Tanzania

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Journal of environmental Science and Engineering(A) 2012年第3期1卷 303-310页

作者： Shadrack Mwakalila Petro Masolwa . Department of Geography University of Dar es Salaam Dar es Salaam Tanzania Department of environmental Conservation WWF-Tanzania Country Office Dares Salaam Tanzania

environmental flow Assessments （EFAs） are becoming the global standard for determining the amount of water required to sustain aquatic ecosystems and sustain socio-economic development. EFAs comprise structured, science-based approaches to determine how much water must be left in the river to protect the aquatic ecosystems and achieve the desired ecological state, The building block methodology （BBM） that was used in this study is designed to identify a series of important flows （the building blocks） which will together provide the essential aspects of the natural hydrological regime that ensure the persistence of as much of the biodiversity as possible. The results show that a total inflow into eastern wetland of 5.52-6.81 m^3/s is required in order to sustain an outflow of 1-2 m^3/s past Ng＇iriama and hence meet the ＂minimum＂ recommended flow rates further downstream at BBM1 and BBM2 during the drought low flow conditions. The rationale being that a satisfactory flow during drought low flow conditions will guarantee sufficient flows during low flow periods in normal and wet years. The low flows of 2.5 m^3/s and 19 m^3/s are recommended for the driest and wettest months, respectively.

关键词： environmental flow Great Ruaha River building block methodology.

Multi-Reservoir Optimization for Maximization of Releases for Hydropower Generation Considering environmental flow

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Journal of Water Resource and Protection 2021年第12期13卷 931-944页

作者： Pushpak D. Dabhade Dattatray G. Regulwar Department of Civil Engineering Government College of Engineering Aurangabad India

Water is the soul of the world. It is the most important element for the survival of humans, animals, birds, plants and all other living things on earth. Water is essential for the beginning of life as well as regular availability of water ensuring the survival, growth and overall nourishment. Thus, proper planning and use of reservoir water are essential for all. To tackle this issue different optimization techniques underline their need and importance in the reservoir operations. In the present study, multi-reservoir optimization model is developed using Python programing language considering the objective of maximization of total annual release for hydropower generation. Model is applied to 3 reservoirs from Godavari River basin from Maharashtra state India. Water essential for conservation of environment has also been made available in river as environmental flow as per the recommendations of Central Water Commission (CWC) India. Developed optimization model provides optimal monthly operation policies.

关键词： Optimization Multi-Reservoir Reservoir Operation environmental flow Linear Programming

Sustainable Multi-Objective Multi-Reservoir Optimization Considering environmental flow

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Journal of Water Resource and Protection 2021年第12期13卷 945-956页

作者： Pushpak D. Dabhade Dattatray G. Regulwar Department of Civil Engineering Government College of Engineering Aurangabad India

Increasing demand for water from all sectors presents a challenge for policy makers to improve water allocation policies for storage reservoirs. In addition, there are many other organisms and species present in river waters that also require water for their survival. Due to the lack of awareness many times the minimum required quantity and quality of water for river ecosystem is not made available at downstream of storage reservoirs. So, a sustainable approach is required in reservoir operations to maintain the river ecosystem with environmental flow while meeting the other demands. Multi-objective, multi-reservoir operation model developed with Python programming using Fuzzy Linear Programing method incorporating environmental flow requirement of river is presented in this paper. Objective of maximization of irrigation release is considered for first run. In second run maximization of releases for hydropower generation is considered as objective. Further both objectives are fuzzified by incorporating linear membership function and solved to maximize fuzzified objective function simultaneously by maximizing satisfaction level indicator (λ). The optimal reservoir operation policy is presented considering constraints including Irrigation release, Turbine release, Reservoir storage, environmental flow release and hydrologic continuity. Model applied for multi-reservoir system consists of four reservoirs, i.e., Jayakwadi Stage-I Reservoir (R1), Jayakwadi Stage-II Reservoir (R2), Yeldari Reservoir (R3), Siddheshwar Reservoir (R4) in Godavari River sub-basin from Marathwada region of Maharashtra State, India.

关键词： Optimization Multi-Objective Analysis Multi-Reservoir Reservoir Operation environmental flow Linear Programming Fuzzy Logic

Numerical Study of the Evolution of a Sea-Breeze Front Under Two environmental flows

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Journal of Meteorological Research 2015年第3期29卷 446-466页

作者：梁钊明王东海 State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences

The evolution of a sea-breeze front （SBF） in parallel and offshore environmental flows was investigated by using high-resolution simulations of two SBF cases from the Bohai Bay region, China. The results show that the combination of a distinct vertical wind shear caused by the sea-breeze circulation with a neutral or slightly stable atmospheric stratification associated with the thermal inner boundary layer promoted the occurrence and maintenance of a Kelvin-Helmholtz billow （KHB）. In a parallel environmental flow, the SBF evolved into a few connected segments because of the inhomogeneity of the sea-breeze direction and intensity as it penetrated inland. A significant upward vertical motion occurred at the two ends of the SBF segment owing to the sea-breeze convergence and was accelerated by the KHB. The KHB made a notable contribution to the intensity at the ends of the segment, whereas the intensity at the middle segment was primarily attributed to the convergence between the sea breeze and the parallel flow. In the offshore environmental flow, the clockwise rotation of the offshore flow varying with time increased the downstream convergence of the interface between the sea breeze and the offshore flow and pushed the downstream convergence zone to an orientation consistent with the offshore flow. The air parcels ascending from the downstream part of the SBF were continuously lifted by the downstream convergence zone during their advection, leading to a significant downstream development of the SBF. The significant upward vertical motion caused by the sea-breeze convergence behind the upstream end of the SBF was shifted to the upstream end of the SBF by the KHB, which enhanced the intensity of the upstream end of the SBF.

关键词： sea-breeze front environmental flow numerical study Kelvin-Helmholtz billow

Suitable Weir Heights to Improve the Provision of environmental flows in Urban Rivers

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Engineering 2021年第2期7卷 187-194页

作者： Yuanyuan Sun Xin’an Yin Xianqiang Mao Enze Zhang Yanwei Zhao State Key Laboratory of Water Environment Simulation School of EnvironmentBeijing Normal UniversityBeijing 100875China

Many studies have been conducted on environmental flow(e-flow)assessment and supply,but e-flow shortages remain common in many urban *** addition to known reasons such as ever-increasing competition among water users and inadequate execution of designed e-flow supply plans,we propose that designing weir heights without explicitly considering e-flows is another major cause of this *** this paper,we suggest that the measures for satisfying e-flows be extended from the water supply stage to the river channel design *** establish a new weir height determination framework that would more effectively satisfy the required *** new framework differs from previous frameworks,in which flood control and water retention are the major concerns and the flow during floods is set as the *** the new framework,e-flow provision and flow velocity maintenance are added concerns and the actual flows for e-flow supply are set as the *** a case study of the new framework’s effectiveness,we applied it to the Shiwuli River,a typical channelized urban river in Hefei,*** old framework specified too-high weir height to meet the e-flow requirements,whereas the new framework offered more reasonable heights that improved e-flow provision.

关键词： environmental flow Urban rivers River restoration

A New Method of Assessing environmental flows in Channelized Urban Rivers

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Engineering 2018年第5期4卷 590-596页

作者： Xin-An Yin Zhifeng Yang Enze Zhang Zhihao Xu Yanpeng Cai Wei Yang State Key Laboratory of Water Environment Simulation School of Environment Beijing Normal University Beijing 100875 China

Assessing environmental flows （e-flows） for urban rivers is important for water resources planning and river protection, Many e-flow assessment methods have been established based on species＇ habitat pro- vision requirements and pollutant dilution requirements, To avoid flood risk, however, many urban rivers have been transformed into straight, trapezoidal-profiled concrete channels, leading to the disappearance of valuable species, With the construction of water pollution-control projects, pollutant inputs into rivers have been effectively controlled in some urban rivers, For these rivers, the e-flows determined by tradi- tional methods will be very small, and will consequently lead to a low priority being given to river pro- tection in future water resources allocation and management, To more effectively assess the e-flows of channelized urban rivers, we propose three e-flow degrees, according to longitudinal hydrological con- nectivity （high, medium, and low）, in addition to the pollutant dilution water requirement determined by the mass-balance equation, In the high connectivity scenario, the intent is for the e-flows to maintain flow velocity, which can ensure the self-purification of rivers and reduce algal blooms; in the medium connectivity scenario, the intent is for the e-flows to permanently maintain the longitudinal hydrological connectivity of rivers that are isolated into several ponds by means of weirs, in order to ensure the exchange of material, energy, and information in rivers; and in the low connectivity scenario, the intent is for the e-flows to intermittently connect isolated ponds every few days （which is designed to further reduce e-flows）, The proposed methods have been used in Shiwuli River, China, to demonstrate their effectiveness, The new methods can offer more precise and realistic e-flow results and can effectively direct the construction and management of e-flow supply projects,

关键词： environmental flow Urban river Channelized rivers River restoration

Restoring environmental flows and improving riparian ecosystem of Tarim River

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Journal of Arid Land 2010年第1期2卷 43-50页

作者： Zhang, JieBin Wu, GuiHua Wang, QiMeng Li, XiaoYan Chinese Acad Sci Xinjiang Inst Ecol & Geog Urumqi 830011 Peoples R China

Rapid population growth and artificial oasis enlargement did pose great threat to the natural riparian ecosystems of Tarim River and caused seriously ecological deterioration and greater desertification of the Tarim River Basin in the second half of 20 century. Restoration of the endangered riparian ecosystem requires that environmental flow should be restored through restricted and uncontrolled flow diversion irrigation in tributary areas. Implementation of such restriction needs further the basin-wide reallocation of water resources through a set of engineering and non-engineering measures taken to ensure the water requirement in the tributary and maintain effective flows in Tarim River. As one of evolving HELP (Hydrology for Environment, Life and Policy) basins, the article first presents an overview of hydrology, socio-economic development and ecosystem evolution of the Tarim River Basin. Then, those measures for restoring and maintaining environmental flow are reviewed and analyzed along with its applicability and validity. The issues emerging in implementing those measures are also explored, and then the conclusions were summarized. Lessons learned could provide a good example for other basins under similar conditions.

关键词： environmental flow IWRM riparian ecosystem Tarim River HELP

Methodology to determine regional water demand for instream flow and its application in the Yellow River Basin

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Journal of environmental Sciences 2006年第5期18卷 1031-1039页

作者： ZHANG Yuan YANG Zhi-feng Wang Xi-qin School of environmental Sciences State Key Laboratory of Water Environment Simulation Beijing Normal University Beijing 100875 China Chinese Research Academy of environmental Sciences Beijing 100012 China School of Natural Resources and Environment Renmin Universitiy of China Beijing 100872 China

In order to realistically reflect the difference between regional water demand for instream flow and river ecological water demand as well as to resolve the problem that water demand may be counted repeatedly, a concept of regional water demand for minimum instream flow have been developed. The concept was used in the process of determining river functions and calculating ecological water demand for a river. The Yellow River watershed was used to validate the calculation methodology for regional water demand. CaIculation results indicate that there are significant differences in water demands among the different regions. The regional water demand at the downstream of the Yellow River is the largest about 14.893 × 10^9 m^3/a. The regional water demand of upstream, Lanzhou-Hekou section is the smallest about -5.012 × 10^9 m^3/a. The total ecological water demand of the Yellow River Basin is 23.06 × 10^9 m^3/a, about the 39% of surface water resources of the water resources should not exceed 61% in the Yellow River Basin. Yellow River Basin. That means the maximum available surface The regional river ecological water demands at the Lower Section of the Yellow River and Longyangxia-Lanzhou Section exceed the surface water resources produced in its region and need to be supplemented from other regions through the water rational planning of watershed water resources. These results provides technical basis for rational plan of water resources of the Yellow River Basin.

关键词： regional water demand instream flow environmental flow methodology the Yellow River Basin

Assessment of impact of water diversion projects on ecological water uses in arid region

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Water Science and Engineering 2013年第2期6卷 119-130页

作者： Song-hao SHANG Hui-jie WANG State Key Laboratory of Hydroscience and Engineering Tsinghua University Yellow River Engineering Consulting Co. Ltd.

In arid regions, large-scale water diversion from rivers leads to significant changes in river flow regimes, which may have large impacts on ecological water uses of river-dependent ecosystems, such as river, lake, wetland, and riparian ecosystems. To assess the integrated impact of water diversion on ecological water uses, we proposed a hierarchy evaluation model composed of four layers representing the evaluation goal, sub-areas of the influenced region, evaluation criteria, and water diversion schemes, respectively. The evaluation criteria for different types of ecological water uses were proposed, and the analytical hierarchy process was used for the integrated assessment. For a river ecosystem, the percentage of mean annual flow was used to define the grade of environmental flow. For a lake ecosystem, water recharge to the lake to compensate the lake water losses was used to assess the ecological water use of a lake. The flooding level of the wetland and the groundwater level in the riparian plain were used to assess the wetland and riparian ecological water uses, respectively. The proposed model was applied to a basin in northern Xinjiang in northwest China, where both water diversion and inter-basin water transfer projects were planned to be carried out. Based on assessment results for the whole study area and two sub-areas, an appropriate scheme was recommended from four planning schemes. With the recommended scheme, ecological water uses of the influenced ecosystems can be maintained at an acceptable level. Meanwhile, economical water requirements can be met to a great extent.

关键词： arid region water diversion project environmental impact assessment ecological water use environmental flow riparian forest analytic hierarchy process