Streamflow regulation from a reservoir: Application of the FTAIS method

Streamflow regulation from a reservoir: Application of the FTAIS method

Klein, J.

Roche, P.A. (mentor)

Civil Engineering and Geosciences

Watermanagement

Erasmus, Ecole national des Ponts et Chaussées, paris

1991-01-01

This report deals with a method to regulate the releases from a waterreservoir. The researched method makes daily outflow decisions. The method is called the FTAIS method (Fil Tendu en Avenir Incertain Simulé; in English : stretched thread method applied to uncertain future). Scenarios are generated to simulate the future inflows into the reservoir. The scenarios consist of daily inflow data. The scenarios are generated, using generated daily rainfall data. The rainfall minus the evapotranspiration (mean daily values are used) is the input into the rainfall-runoff model (GR 3), this model computes the simulated flows into the reservoir. The mass curves of the simulated inflows are used in the stretched thread part, this stretched thread part is derived from a graphic method (see figure) to compute the flow that is to be released from a reservoir. In former studies (X. YANG; 1989) the average scenario is calculated and used as input into the stretched thread method. In this report variants of the stretched thread method have been studied. To test these variants, the regulation at the reservoir Bar sur Seine is simulated. The principles of the studied variants are: 1. The A-calculation method; Several initial outflows (corresponding to A values) are tested. ' The consequences are calculated for each scenario, if the proposed outflow had been taken at the first day of that scenario. The consequences are expressed using a cost function, the sum of the costs corresponding to one outflow value is calculated. The outflow corresponding to the least sum is selected. 2. Reserve capacity method; The reservoir is divided into three parts. Only one part is used in ' regular situations. In periods when extreme floods or shortages occur, the reserve capacity parts for flood reduction or the part for flow augmentation are also used. A combination of both methods is also tested. These new variants result in a better regulation (a lower standard deviation of the regulated flows) than the original method, but the new methods are more complicated and time consuming than the original one. The influence of the upstream riverbasin area and the reservoir capacity is also investigated. Larger reservoirs and larger riverbasins result in lower standard deviations (expressed in mm/day- flow divided by the riverbasin area) of the regulated flows. The simulations with several reservoir capacities can be useful to determine the optimum regulation method and the capacity, when it is decided that a reservoir will be constructed. The desired characteristics of the outflows (standard deviation, probability of occurence of extreme regulated flows) might determine the needed capacity.

reservoir
reservoir management

http://resolver.tudelft.nl/uuid:9ae9165c-6c4f-407d-84e6-e10484af9299

Student theses

master thesis

(c) 1991 Klein, J.