The impacts of Upper Blue Nile Dams construction on agricultural water availability of Sudan

The objective of this research is assessing water resource availability in the Blue Nile River for different development scenarios using Mike Hydro modeling. The long term Blue Nile total irrigation water demand will be more than 46.67 × 109m3, which is nearly similar to the naturalized flow (around 48 × 109m3). In the phase II irrigation, water shortfalls increase to 0.38 × 109m3/year. There is up to 2.172 × 109m3/year irrigation water deficit at the full development level in Ethiopia. Due to flow regulation, there are no shortfalls in irrigation in Sudan in either the medium or the long-term. Dams located in Ethiopia give more advantage to the Sudanese schemes than that of Ethiopian regarding irrigation development.

Impact of large reservoirs on simulated discharges of Brazilian rivers

ABSTRACT Tens of thousands of dams were built around the world to reduce flood risks, produce energy, and maximize benefits of limited freshwater resources. In Brazil, the main and largest reservoirs are related to hydropower plants. Improving the understanding of reservoir dynamics is important not only to evaluate their impact in the flow regime of Brazilian rivers, but also to simulate the combined effect of constructing new dams and potential alterations under future climatic conditions. Here, we analyze how an ideal representation of reservoirs in terms of forced discharge would improve a previously calibrated hydrological model under the Brazilian domain. We forced the continental-scale version of the MGB model on observed reservoir outflows from 109 hydropower dams, which are part of the Brazilian National Interconnected System controlled by the National Electrical System Operator. Model simulated flows were replaced by the reservoir outflows in all dam locations and were compared to the original discharge in downstream gauges. The forced discharge simulation presented a mean improvement for Kling-Gupta Efficiency of 21%, when compared to the original model (naturalized flow). This analysis is a preliminary step towards an explicit representation of the reservoirs in the model, what will be conducted in a future study.

Quantification of Environmental Flow Requirement of the Khun Dan Prakan Chon Dam Using Hydrological-Hydraulic-Habitat Simulation Methods

With increased water demand, reservoir operation has become more complex with the need to quantify the exact amount of water needed for each demand sector. The environmental flow requirement, also known as instream flow is regarded as the first-prioritized objective of the multipurpose water resources projects in Thailand. The capability of reservoirs in Thailand to allocate water for environmental needs depends on available supply, strategies and operating policy. Therefore, this study aims to assess the environmental flow requirements of Khun Dan PrakanChon Dam using three methods; 1) the hydrological method (Tennant, Tessmann, 7Q10, FDC, and VMF), 2) hydraulic method (R2CROSS and wetted perimeter) and 3) habitat simu-lationmethod, using the PHABSIM model for physical habitat simulation of aquatic organisms in the Nakhon Nayok River. The hydrological approach was performed under the historically-naturalized flow data of the NY.1B station and established hydrologic flow regime during low flow and high flow months. The environmental flow rates obtained from two hydraulic methods were based upon field observations at the NY.1B station significantly. However, the biological conditions and interactions of aquatic organisms in the river were not principally characterized in hydrologic and hydraulic approaches. In addition, the estimated results performed by habitat simulation model gave an additional meaning of ecological flow needs mainly for aquatic habitat conservation in the river. By integrating the conditions of hydrologic and hydraulic flow regimes as well as the habitat conservation objectives, environmental flow rates of 8-10 cm were recommended to determine the downstream release of Khun Dan Prakan Chon Dam; these recommendations were very close to those derived using the Tessmann, 7Q10 and PHABSIM methods-Tennant and flow duration curve methods.