**Hydrology prediction model (HYPROM)**

HYPROM model is developed to simulate overland watershed processes. It is designed to be easily applied to different watersheds and across a broad range of spatial scales, from local to regional and global. HYPROM can be useful tool for predicting short-term flood events, as well as for water balance assessments and climate studies (Nickovic et al., 2010).

Unlike most other hydrology models based on a kinematic approximation in which the Manning velocities are calculated diagnostically (Jones et al., 2008), the HYPROM system is based on governing mass- and momentum-conserving shallow water equations in which the momentum and continuity equations are treated prognostically (Nickovic, 2007). As a grid-point model, HYPROM was developed over the horizontal semi-staggered E grid (Arakawa and Lamb, 1977) that experiences the problem of gravity-wave decoupling. Although several techniques have been developed to reduce short gravity-wave noise (Janjic and Mesinger, 1989; Janjic, 1974; 1979), a new method for mass water redistribution was introduced in HYPROM to fully suppress the noise (Nickovic et al., 2010). The horizontal advection scheme is mass conserving and does not create new extremes or negative height values (Janjic*,* 1997). Furthermore, an explicit forward-backward time scheme is used for the gravity waves as the fastest wave component in the model, which provides an efficient time integration of the model. In order to avoid numerical instability, a friction slope term is parameterized using unconditionally stable and numerically convergent implicit scheme.

HYPROM consists of two sub-models: two-dimensional representation of overland flow and one-dimensional river routing component that collects the excess water in a drainage basin. It uses real topography, river routing and soil texture data from USGS datasets.

HYPROM model is driven with the advanced non-hydrostatic NCEP/NMME atmospheric model (Janjic et al., 2001; Janjic, 2003), which is widely used to produce operational weather forecasts. It simulates precipitation and calculate surface and base runoff from rainfall and snowmelt using the NMME land surface scheme. In this manner, NMME provides the vertical component of water flow through the soil.

**REFERENCES**

**Arakawa A., **and **V. R. Lamb** (1977), Computational design of the basic dynamical processes of the UCLA general circulation model, Meth. Comp. Phys., 17, 173–265.

**Janjic Z. I.** (1974), A stable centered difference scheme free of the two-grid-interval noise, Mon. Wea. Rev., 102, 319-323.

**Janjic Z. I.** (1979), Forward-backward scheme modified to prevent two-grid-interval noise and its application in sigma coordinate models, Contributions to Atmospheric Physics, 52, 69-84.

**Janjic Z. I.** (1997), Advection scheme for passive substances in the NCEP Eta model, Research Activities in Atmospheric and Oceanic Modelling, WMO, Geneva, CAS/JSC WGNE, 3.14.

**Janjic Z. I.** (2003), A Nonhydrostatic Model Based on a New Approach, Meteorology and Atmospheric Physics, 82, 271-285.

**Janjic Z. I., **and** F. Mesinger** (1989), Response to small-scale forcing on two staggered grids used in finite-difference models of the atmosphere, Quarterly Journal of the Royal Meteorological Society, 115, 1167-1176.

**Janjic Z. I., J. P. Gerrity, Jr.** and **S. Nickovic** (2001), An Alternative Approach to Nonhydrostatic Modeling, Mon. Wea. Rev., 129, 1164-1178.

**Jones J. P., E. A. Sudicky,** and **R. G. McLaren** (2008), Application of a fully-integrated surface-subsurface flow model at the watershed-scale: A case study, Water Resour. Res., 44, W03407, doi:10.1029/2006WR005603.

**Nickovic S.** (2007), Coupled atmosphere-hydrology system for routine prediction of overland water flow . Research Activities in Atmospheric and Oceanic Modelling, WMO, Geneva, CAS/JSC WGNE, Sect. 20, 17-18.

**Nickovic S., G. Pejanovic, V. Djurdjevic, J. Roskar** and **M. Vujadinovic **(2010), HYPROM Hydrology surface-runoff prognostic model, Water Resources Research, 46, W11506, doi:10.1029/2010WR009195.

**Nickovic S., V. Djurdjevic, M. Vujadinovic,** **Z.I. Janjic, M. Curcic** and **B. Rajkovic** (2011), Method for efficient control of shortest wave decoupling on semi-staggered grids in case of single point forcing, Journal of Computational Physics, 230 (5), 1865-1875, doi:10.1016/j.jcp.2010.11.037.