Adjustment of Remotely Sensed Precipitation using Discharge

<p>With the expected increase in flooding due to climate change, accurate estimation of precipitation and the resulting modelled hydrographs are an essential requirement for reliable flood forecasts. At present, most adjustment methods for remotely sensed precipitation require raingauge data to increase the accuracy of the precipitation estimates. One disadvantage is that raingauges only measure precipitation at a given point and usually there are a relatively small number of these points in a typical catchment (and some smaller catchments may not have any raingauges). River discharge from the catchment integrates the influence of catchment-wide precipitation and can often be more accurately measured than the areal rainfall, especially in areas with a sparse raingauge network. Here, we present a non-raingauge adjustment method for remotely sensed precipitation estimates that utilises discharge data only to adjust these estimates for input to hydrological models. This method allows a hydrological model to adjust its treatment of precipitation input, through an additional model parameter, by comparing the observed and modelled hydrographs. This proposed method is comparable to a traditional raingauge adjustment methods over a number of catchments and hydrological models, for both peak flows and for the entire hydrograph. Additionally, this method allows for the adjustment of catchment averaged raingauge precipitation measurements to correct for any possibly errors due to using point data i.e. spatial density or representative issues. This results in a substantial improvement in discharge estimation compared to the un-adjusted raingauge measurements.</p>