Traditional methods of deducing the T-hour unit hydrograph,such as the least-square method,are prone to create zigzagged oscillations of the resulting hydrographs,and the surface runoff depth is hardly equal to the net rainfall.

Watershed instantaneous unit hydrograph based on information entropy theory;

Combining with a brief review of the basic conception on concentration curves of flood waves in river and instantaneous unit hydrograph in watershed,the unit(or dimension) of some common-used concentration curves are analyzed,interpreted in detail and given clearly.

Parameter estimation for lag-instantaneous unit hydrograph with entropy method;