Jasna Plavšić

Stochastic structure of annual discharges of large European rivers

Abstract Water resource has become a guarantee for sustainable development on both local and global scales. Exploiting water resources involves development of hydrological models for water management planning. In this paper we present a new stochastic model for generation of mean annul flows. The model is based on historical characteristics of time series of annual flows and consists of the trend component, long-term periodic component and stochastic component. The rest of specified components are model errors which are represented as a random time series. The random time series is generated by the single bootstrap model (SBM). Stochastic ensemble of error terms at the single hydrological station is formed using the SBM method. The ultimate stochastic model gives solutions of annual flows and presents a useful tool for integrated river basin planning and water management studies. The model is applied for ten large European rivers with long observed period. Validation of model results suggests that the stochastic flows simulated by the model can be used for hydrological simulations in river basins.

Annual and seasonal discharge prediction in the middle Danube River basin based on a modified TIPS (Tendency, Intermittency, Periodicity, Stochasticity) methodology

Abstract The short-term predictions of annual and seasonal discharge derived by a modified TIPS (Tendency, Intermittency, Periodicity and Stochasticity) methodology are presented in this paper. The TIPS method (Yevjevich, 1984) is modified in such a way that annual time scale is used instead of daily. The reason of extracting a seasonal component from discharge time series represents an attempt to identify the long-term stochastic behaviour. The methodology is applied for modelling annual discharges at six gauging stations in the middle Danube River basin using the observed data in the common period from 1931 to 2012. The model performance measures suggest that the modelled time series are matched reasonably well. The model is then used for the short-time predictions for three annual step ahead (2013–2015). The annual discharge predictions of larger river basins for moderate hydrological conditions show reasonable matching with records expressed as the relative error from −8% to +3%. Irrespective of this, wet and dry periods for the aforementioned river basins show significant departures from annual observations. Also, the smaller river basins display greater deviations up to 26% of the observed annual discharges, whereas the accuracy of annual predictions do not strictly depend on the prevailing hydrological conditions.

A normalized regression based regional model for generating flows at ungauged basins.

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-Sutcliffes 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%.

Consequences of Non Planned Urban Development During Turbulent Times in Serbia — Case Study of Suburb Kumodraz Watershed in Belgrade

Development is usually based on numerous analyses accounting for planning, economy and population assessments as well as urbanism, architectural and civil engineering infrastructure planning and project design. The modern city planning begun during Napoleon in Paris, while modern urban planning in Belgrade started in mid nineteenth century. At the end of twentieth century turbulent times occurred in the area of ex Yugoslavia so that numerous plans of development started being misused or never completely respected. Actually, during 1990s urban development in cities of Serbia became rather uncontrolled. In addition, during 1990s many people moved from rural places to, to their opinion, more promising places, most frequently to the Capital city. This paper presents a series of consequences of non planned urban development on sewer infrastructure operation. Those includes high construction rate including increase of number of inhabitants at suburban part, namely watershed of the brook Kumodraz at the southern part of the city of Belgrade. Those changes were noticed during preparation of preliminary design for the reconstruction and upgrading of the combined waste water system at this part of the city. The design preparation included measurements of wastewater and rainfall runoff at the downstream outlet. During measurement period, which started in 1997, significant differences occurred in the both base flow, i.e. dry weather flow, as well as in peak flows during moderate and severe rainfall events.