Water Flow Forecasts for its Rational Use in Industry

Basilashvili Ts. Z..

Georgian Hydrometeorological Institute, Tbilisi, Georgia
e-mails: nb@gw.acnet.ge; jarjitabatadze@yahoo.com

Abstract

Reservoirs are the most efficient means of managing water resources for the aim of their regulation and rational use. Hydroelectric stations (HES) (30 in Western and 7 in Eastern Georgia), irrigation and drainage canals and aqueducts for water supply have been constructed. Their exploitation is greatly dependent upon the quality and timeliness of hydrological prognosis. Having efficient methods for forecasting water flow to the water reservoirs is of paramount importance as only they can ensure no stoppage in operation of the HES and other systems.
There have been investigated the Djvari reservoir, as the most powerful of all the HESes in Transcaucasia is situated there, and the Zhinvali HES that is used for irrigation purposes, produces electricity and supplies Tbilisi with water. Initially the norms of the main flows for various periods of year and their portions within a year were established.
For the purpose of prognosticating the water flow into the water reservoirs in the conditions of the limited hydro-meteorological information there has been used a statistical, multifactoral model, where main flow formation factors are included and their temporary dynamics is calculated in the flow formation. Qualitative and quantitative composition of the predictors is identified through the method of multi-stage sifting. Expediency of including each following predictor is controlled with various mathematical criteria.
In estimation of the prognostic equations there has been included direct and reversed development of multifactor dependencies that simultaneously enables to investigate the possibility of prognostication with minimal initial data, increase the beforehand period and ignore the factors of the period under prognosis.
There has been set up computer software for realization of all the calculations and establishing optimal prognostic equations. The investigations have led to working out long and short term prognosis of water flow for different periods of year. For the main flows there have been prognosticated the average and maximum expenditures of high waters, vegetation, quarterly, monthly, decade and daily expenditures of rain high waters. General territorial prognosis of high waters have been drawn up for yet not investigated, lateral inflows as they rather frequently create danger for water reservoirs and the environment.
Based on various initial information different advance and accuracy there have been established several prognostic equations. Calculations with various versions enable to identify possible intervals of the expected flow and cross-control the obtained results, furthermore it enables to forecast not only once, as usual, but several times with different advance in order to specify prognosis step by step through adding fresh information.
These prognoses facilitate to planning and using hydro resources comparatively successfully and efficiently that, in its turn, results into increase of generating more electricity, increase the area of irrigated lands and water supply. Timely prediction of high water floods not only prevents disaster but also leads to significant economic benefit.