|其他摘要||The main Tarim River is located in an extreme arid region. It is very important to quantify the interaction between hydrological process and ecological process for this ecological fraige region. We first studied the dynamic of the eco-hydrological processes in past 60 years. And then the main hydrology process and ecological processes of main Tarim River was revealed. Based on this, the eco-hydrological model framework was bulid up, and the interaction between ecological and hydrological process in riprian ecosystem and artificial ecosystem of Tarim River was simulated.
(1) We analyzed the dynamic of the hydropogy and ecology components along the main tarim river since 2000, such as: runoff, groundwater, community structure, and vegetation dynamic et al,. And we found that the interactions among river, shallow groundwater, soil water and vegetation are the key hydrology processses along the main Tarim River, and the vegetation dynamic driven by hydrology components (such as groundwater depth) is one of the major ecology processes.
(2) An ecohydrological modeling framework, which incorporated the most widely used groundwater model(MODFLOW), soil water model(HYDRUS 1D), a flood inundation model, a vegetation dynamic model and a vegetation crop growth model, was build up to describe eco-hydrology processes along the main tarim river. Three case applications were carried out.
(3) The reponses of groundwater and vegetation dynamic to the ecological water convergence in lower reach of Tarim River, could be well decribed by ecohydrological model framework. After 6 year water convergence, the total amount of groundwater recharge from river was 1.97×109 m3, taking 87.4% of the total amount of water convergence, the water consumed by evapotranspiration(bare soil evaporation and vegetation transpiration) was 1.04×109 m3, taking 46.1% of the amount of total water convergence, the groundwater storage was increased by 1.05×109 m3. And the evapotranspiration is an important component in the ecohydrology processes in lower reach of Tarim River. The evapotranspiration is impacted by the groundwater depth and the vegetation, and it is increased significantly, when groundwater table rising and vegetation recovering. The vegetation recovery has significant impact on hydrology processes, it could increase the evapotranspiration by 3770880 m3, and decrease the groundwater table.
(4) At the mid reach of Tarim river, we found that model could well describe the dynamic of groundwater table, soil water content, inundation area, inundation depth and vegetation growth status in both spatial and temperoal, when water is realeased from gate. At the same time, model also could well descrbed the water stress difference between populus and tamarix due to the different biomass distribute stratigies. And we found that the best irrigation time is in July, which give smallest water stress suffered in this region. We also develop a function that describe the dependence of water stress on water release amount, and predicted the future vegetation pattens under water realease scenario based on some assumptions.
(5) We studied the impact of groundwater depth on root zone water balance and cotton growth in cotton field with our model. We found that cotton growth and root zone water balance are very sensitive to the depth of the groundwater table and that cotton growth, in turn, affects subsurface water fluxes, such as capillary rise. Additional model simulations showed that groundwater is a major source of water for cotton growth. Compared to a control run that had no groundwater, 23% of crop transpiration is supplied by a capillary rise from groundwater, producing an increase in cotton yield by 20%. And the mulch could increase root water uptake could by 2.6%, reduced soil evaporation by 86.5%, reduce root zone soil water loss and increase drainage by 25.6%.
So we could conclude that the ecohydrological model we build up could be used to help for water resource management and protecting ecology system in main Tarim River.|