考虑植被生理生态特征变化的生态水文过程模拟

Modeling Ecohydrological Processes under Influence of Dynamic Variations of Vegetation Physiology and Ecology

基于分布式水文-土壤-植被模型(DHSVM),考虑气候干湿条件下植被水分胁迫作用及水分利用适应性,提出了植物最小气孔阻力r smin随降雨量变化的蒸散发计算模式.根据枯期退水特征分析,提出了反映径流退水特征的两段式土壤渗透性衰减系数,实现了对DHSVM的改进.根据东江红壤丘陵区植被分布特征,选取星丰流域,采用现场观测、室内分析,结合遥感反演技术,确定研究区植被及土壤特征参数.利用2003—2008年实测气象、水文资料进行参数率定和模型验证.采用扰动分析方法分析土壤和植被参数变化对径流及蒸散发量影响的灵敏度.结果表明:改进的模型能较好地模拟植被生理特征随环境变化的生态水文过程,提高了流域水文过程模拟精度,为分析下垫面变化的生态水文效应提供科学依据.

Based on the Distributed Hydrology-Soil-Vegetation Model（DHSVM）,the evapotrmspiration model was improved by adjusting the minimum resistance of vegetation rsmin in relation to precipitation amount.This improvement enables the model to reflect the plant water stress and adaptive mechanism under dry and wet climate conditions.Two values of soil permeability decrease coefficients were adopted to reflect the basin flow recession characteristics according to the analysis of low flow recessions.Thus DHSVM was improved.A small basin of Xingfeng in Dongjiang hilly region with red-soil was selected as a study area.Model parameters related to vegetation and soil were determined on the basis of both remote sensing（RS） data and field and laboratory experiments.Hydrological and meteorological observation data during 2003 and 2008 was used for parameter calibration and model verification.Perturbation analysis method was used for analyzing sensitivity of parameters to runoff and evapotranspiration.The simulated results demonstrated that the improved model well captures ecohydrological processes under influences of vegetation physiologic and ecologic variations,and increases simulation accuracy for hydrological processes.This study offers a scientific basis for analyzing effects of land use and land cover changes on ecohydrology.