Potentiality Of Gpm Satellite Rainfall Products In Near-real-time Flood Forecasting

Flood is an unavoidable natural disaster.With the changes in global climate,the increasing frequency of flood and drought and the grow of peak flow runoff in recent year,flood seriously endanger human society and property.Flood is not only a natural disaster,but also a natural resource which can be of great use.The issue of efficient usage of flood has won great attention all over the world.Real-time flood forecasting is an important basis for flood protection and water resource management.Accurate real-time flood forecasting is of significance to flood protection,reservoir operation and water resource management.However,due to the lack of rainfall data,building an accurate real-time flood forecasting is difficult in some remote areas and areas with complicated topography.The development of GPM IMERG satellite rainfall product provides us a new way to obtain rainfall data.People can easily obtain satellite precipitation data without the limit of topographical conditions by use of it,which is important to ungauged basin.Ground validation is conducted on satellite rainfall product by analyzing the difference between GPM IMERG satellite rainfall product and gauge rainfall data while hydrological validation is conducted as well by the data input of GPM IMERG satellite rainfall product as hydrological model.These two means aim to explore the potentiality of applying GPM IMERG satellite rainfall product on real-time flood forecasting.Han River Basin in China and Nam'Ou River Basin,which is the branch of Mekong River in Laos,are the research objects.After exploring the data in various basin scales and various rain-gauge densities,the main results are shown as followed:(1)According to ground validation,IMERG Final rainfall product is higher in amount than gauge data in different basins.However,IMERG Early rainfall product is not consistently higher or consistently lower than gauge date.The probable reason of this result might be that IMERG Early rainfall product uses climate precipitation data to correct while IMERG Final rainfall product uses real rain gauge data;According to hydrological validation,the results of peak values in the simulation by using IMERG rainfall products are worse than those by using rain gauge data.Besides,the simulate results by using IMERG Early rain fall product are greatly different in various basin scales.By applying the methodology of fusing satellite rainfall product and gauge data,the conditions of highly estimation can be improved and the peak flow of simulate results are more accurate.(2)The THREW hydrological model of Nam'Ou River Basin is constructed on basis of satellite rainfall product and can be applied to real-time flood forecasting system for the flood control operation in cascade hydropower stations.(3)An application model of GPM IMERG satellite rainfall product in real-time flood forecasting is put forward.The basin rainfall data is obtained through GPM satellite data and IMERG inversion algorithm.If the satellite signals can be received in specific regions and the inversion algorithm of the satellite rainfall data can be completed,the speed of the inversion algorithm process of rainfall data will be improved.Then,with the revision through the few gauge stations within regions,it would be of great use to the real-time flood forecasting in regions lack of rainfall data.