World has known physics based hydrologic modelling for decades and coming closer to a century. Mathematical models used for water resources applications vary from water agency to water agency and even from a sub division to a sub division of a particular agency. The data requirements, the degree of hydrological complexities, methods of selecting objective functions, methods of calibration and verification varies from one to another. Non availability of guidelines on how to model a watershed, and non-availability of a guidelines on which models to be used, non- availability of data checking and filtering guidance, Non availability of guidance on the models that should be used for planning, that should be used for operations, and that should be used for forecasting creates a significant negative impact on the sustainability of water resources. The ignorance about hydrological modelling that exists among many water users and water decision makers creates confusion and chaos because of the ignorance on the value of outputs produced by water assessments. As a result, only small strides can be taken towards achieving sustainability of water resources.
UMCSAWM has thus far carried out extensive research and case study applications on mathematical modelling of rainfall runoff process providing an excellent platform for a critical evaluation of the prevailing practices of water agencies, advanced water models used by consultancy agencies and detailed models either developed or practiced by the academia. In this backdrop what is presently required is the intervention of regulators or the state for action with greater vision.
Therefore, a policy decision must be taken to identify, evaluate and rank the numerous water model applications within a given country and develop generic guidelines which are evidence based.