A Perspective on Hydrology from the 20th Century to 21th Century

Based on the related sessions on the 22th A ssembly of International Union of Geodesy and Geophysics which was held in July 1999 in Birmingham,there are three basic characteristics of hydrological research from the 20th Century to 21th Century.Firstly, the effects of human activities on hydrological cycle both in water quantity and water quantity are stressed very much,which includes inpact of land-use change on nutrient loads from diffuse sources; inpacts of urban growth on surface and groundwater quality, riverine ecological response to changes in hydrological regine, sedinent transport and nutrient loading, and interactions between surface water and goundwater in quality and quantity.Secondly, the hydrological research in regional scale is focused.The hot topics at present are to establish a global hydrological data bases, to explore new methods which are suitable for regional study over continental regions.The study on the interaction between ahnosphere and land surface greatly promotes regional hydrological research also.Finally, linkage among tracer techniques, advanced hydrometric and remote sensing is very helpful for understanding hydrological processes in catchment.