Taking the mountain watershed at the upper stream of the Heihe River in the Hexi Corridor area in northwest China as an example, some problems with relation to hydrological and ecological researches are discussed from the aspects of mountain hydrological cycle, hydrology and ecosystems, runoff generation and prediction. The spatial and temporal distribution of precipitation and its composition of solid and liquid form are mainly influenced by elevation and topography in the mountains, while evapotranspiration is mainly influenced by various land cover and heterogeneity of underlying surfaces under different elevation and topographic conditions.
The basic characteristics of hydrological cycle and water balance of an inland river basin rest with the fact that the runoff does not run out off from the basin, and the normal annual precipitation and evapotranspiration are equal, forming the local hydrological cycle system: water vapor transportation→precipitation→runoff→evapotranspiration→water vapor transporation. The investigation of this local hydrological cycle redounds to the understanding of the interrelationship of hydrological and ecological processes between the areas at the upper, middle and lower streams of an inland river.
As yet the researches are very inadequate on mountain hydrological and ecological processes and their interactions. In the mountain glaciers, snow and permafrost zone, the researches should be put on the hydrological conditions to maintain the alpine meadow growing. In the mountain vegetation zone, the ecosystems of mountain forest and grass land should be studied on for their functions in the mountain hydrological cycle and for their role in maintaining and protecting the mountain ecosystems and environment. In this way, we can understand as a whole the interactions between hydrological processes and ecosystems and their environmental significance.
The hydrological processes of an inland river basin are very complex, multidisciplinary and comprehensive. The measurements and researches should be strengthened on the various hydrological processes to understand the mechanism of the mountain runoff generation. In this aspect, ground measurements and remote sensing monitoring are mutual compensatory. Based on this, the physical distributed hydrological models should be developed to reflect the complex mountain hydrological processes. In order to bring the measured data into play fully in the simulation, the mountain hydrological data assimilation system should be developed to form the hydrological modeling system. Furthermore, the researches on and developing of the coupled regional atmospheric and hydrologic models should be carried out in the mountain watershed scale. In this way, the incessant improvements of the response simulation and modeling prediction of mountain runoff change will be achieved under the climate change and human activities.