| The Sacramento Soil Moisture Accounting (SAC-SMA) is an empirical and lumped conceptual model that represents the core hydrologic component of the current National Weather Service River Forecast System (NWSRFS). The NWS vision for continuing development and modifications of the NWSRFS include, among other considerations: (a) transitioning from lumped system to a system based on finer spatial and temporal scales, (b) incorporating physically-based models and/or physically-based model parameterization, and (c) developing more effective model calibration schemes that are consistent with distributed modeling paradigm. The NWS's Distributed Model Intercomparison Project (DMIP) is the main vehicle by which researchers from the NWS and the academia can test the capabilities of new modeling strategies.;The main premise of this dissertation is that development of hydrologic forecasting systems, which combine the advantages of lumped models, distributed-physically based parameters, and at the same time, capture the heterogeneities in basin characteristics and hydrometeorological forcing would be an important step towards a smooth transition from lumped to fully distributed models. As such, this dissertation attempts to contribute to the above-described transition by addressing unresolved issues related to the two primary components of operational forecasting systems that are based on distributed models. These components are namely, (a) model structure, and (b) calibration strategies.;To accomplish this objective, the dissertation study first introduces a semi-distributed version of SAC-SMA with different methodologies to route the fast and slow response components of the water balance component. Then, effective parameterization strategies that take the advantage of the strengths of both distributed and lumped approaches are investigated. In the second part, it investigates the value of modifying the NWS distributed hydrologic model (i.e., HL-RDHM) structure in terms of sub-surface water interactions between model elements (i.e., small sub-basins and/or grid cells). |
