Hydrological modelling with components: the OMS3 NewAge-JGrass system

NewAge-JGrass system for forecasting and modelling of water resources in general at the basin scale. As a modern hydrological modelling, it is composed of two parts: (i) the system for data and results visualization based on the Geographic Information System uDig and (ii) the component based modelling system. All the system is based on Java because of its portability. Java is a modern and mature language aware of the web and has features such as multithreading that are essential to build scalable modelling platform. There are a few open source frameworks available that allow adaptation for our task, such as the GeoTools project by the Open GIS Consortium, representing a solid foundation for spatial analysis. OMS was chosen for facilitating model connectivity because of it low invasiveness in code practice and capability in production of leaner and more descriptive modelling code . uDig as visualization/GIS platform, including GIS services, and its integration with the JGrass GIS, developed by http://udig.refractions.net/, offers a spatial toolbox which contains the features previously offered by JGrass. Compared to traditional hydrological models, which are built upon monolithic code, JGrass-NewAge allows for multiple modelling solutions for the same physical process, provided they share similar input and outputs constraints. Modeling components are connected by means of a concise scripting language NewAge-JGrass components can be grouped in several categories. The geomorphic and DEM analyses which solves the problem of basin delineation; the tools for making spatial extrapolation/interpolation of the meteorological data; the estimation of the radiation forcing; the estimation of evapotranspiration; the estimation of the runoff production; the channel routing and tools for automatic model parameter calibration such as DREAM, Particle Swarm and LUCA. NewAge requires interpolated meteorological variables (such as air temperature, precipitation, and relative humidity) as input data for each hillslope. They can be computed by a deterministic or geostatistic approaches. The energy model includes both, shortwave and longwave radiation calculation components for each hillslope. The first implements algorithms that take into account shade and complex topography and cloud cover. Evapotraspiration can be modelled using two different solutions: the Fao-Evapotraspiration model and the Priestley-Taylor model. A snow melting and snow water equivalent model is also part of the system. Duffy's model and Hymod model are the runoff production models implemented in NewAge. In both cases the model is applied for each hillslope. Finally, the discharge generated at each hillslope is routed to each associated stream link. Modeling solutions (connections of different components) are applied in three different river basin and verifications against measured data (discharge, radiation fluxes, snow water equivalent) are presented by using traditional goodness of fitting indices.