Integrated simulation of runoff and groundwater in forest wetland watersheds

AbstractA Distributed Forest Wetland Hydrologic Model (DFWHM) was constructed and used to examine water dynamics in the different climates of three different watersheds (a cold region, a sub-tropic region, and a large-scale watershed). A phenological index was used to represent the seasonal and species changes of the tree canopy while processes of snow packing, soil freezing, and snow and ice thawing were also included in the simulation. In the cold region, the simulated fall of the groundwater level in winter due to soil freezing and rise in spring due to snow and ice melting compare well with the observed data. Because the evapotranspiration and interaction of surface water and groundwater are included in the model, the modeled seasonal trend of the groundwater level in the sub-tropic region is in agreement with observations. The comparison between modeled and observed hydrographs indicates that the simulations in the large-scale watershed managed to capture the water dynamics in unsaturated and saturated zones

On the Variation of NDVI with the Principal Climatic Elements in the Tibetan Plateau

Abstract: Temperature and precipitation have been separately reported to be the main factors affecting the Normalized Difference Vegetation Index (NDVI) in the Tibetan Plateau. The effects of the main climatic factors on the yearly maximum NDVI (MNDVI) in the Tibetan Plateau were examined on different scales. The result underscored the observation that both precipitation and temperature affect MNDVI based on weather stations or physico-geographical regions. Precipitation is the main climatic factor that affects the vegetation cover in the entire Tibetan Plateau. Both annual mean precipitation and annual mean precipitation of the growing period are related with MNDVI, and the positive correlations are manifested in a linear manner. By comparison, the weakly correlated current between MNDVI and all the temperature indexes is observed in the study area