Active water loss management has become one of the primary interests of the water utilities in the world. Due to efforts of the IWA Task Force in the last decade, traditional approach of water loss expression in percentage of system input values has been proven to be misleading in may cases, and new way of performance measuring and benchmarking is proposed. This paper presents the basic principles of this methodology and results of the first step in attempt to approach Serbian water utilities performance according to new standards. Pirot water supply system is used as a case study to estimate pressure reducing impact on technical performance indictor values before introducing active leakage control
Revision of existing methodologies for generating monthly-flow series at ungauged basins based on multivariate nonlinear correlation has led to a simple two-parameter model. While the existing methodology used hydrological, meteorological and geomorphologic input data, the proposed model requires hydrological and geomorphologic input data only. The proposed methodology requires formation of separate pools of donor catchments for model parameter estimates. The proposed two-parameter model and improvement in the sphere of homogeneous region identification were verified using 195 runoff data sets from hydrologic stations in Serbia in the 1961-2005 period, divided into three non-overlapping 15-year periods. Nash-Sutcliffe's model efficiency coefficient (NSE) was used to assess the: (1) quality of proposed model with identified model parameters; (2) quality of a nonlinear multivariate equation for standard normal variables estimation with identified model parameters; (3) quality of proposed model with model parameter estimates. Generated time-series statistics and nonlinear multivariate equation quality are also evaluated. Five model calibration and validation results are shown. Generated flow series variation coefficient is the best replicated statistics with relative absolute error less than 10%.
Borislava Blagojević & Boris Vakanjac: Ocena povprečnega prispevnega zaledja v kraškem vodonosniku z enačbo mesečne vodne bilance z omejenimi meteorološkimi podatki: Uporaba na primeru izvira Grza v vzhodni Srbiji Ob pomanjkanju podrobnih raziskav kraških prispevnih za ledij, se ob izračunih razpoložljivih zalog podtalnice in eleme ntov enačbe vodne bilance, pogosto odraža topografska ve likost prispevne površine, in ne dejanska, aktivna (podzemne) velikost vodonosnika. V primeru krasa se te ocene lahko zelo ra zlikujejo. Prispevek se ukvarja s problemom izračuna povprečne velikosti prispevnega zaledja v razmerah, ko so meteorološki podatki omejeni na padavine in temperature, in ko so podatki o pretokih razpoložljivi za daljše obdobje. Predlagana metodologija je bila uporabljena, popravljena in preizkušena na 15 izvirih v Srbiji. Rezultati dobljeni z mode lom se razlikujejo od hidrogeoloških raziskovalnih rezultatov za 20%. Eden od proučevanih izvirov je izvir Grza, ki izvira iz kraških formacij Kučaj in Beljanica (KarpatoBalkanski lok vzhodne Srbije). V tem prispevku smo na primeru izvira Grza prikazali aplikacijo modela in potrebne izboljšave za napredek iz grafoanalitičnega v analitičen model. Povprečna velikost prispevnega zaledja je povezana s parametrom modela, ki zmanjšuje potencial dejanske evapotranspiracije na mesečni osnovi. Z modelom lahko ocenimo tako velikost prispevnega zaledja, kot tudi dejansko evapotranspiracijo in dinamično prostornino skladiščenja podzemne vode.
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