# Impact of Climate Change on the Major Eco-Hydrological Parameters in the Dongting Lake Basin
## 1 Introduction
As wetland whose main objective is to protect the habitat of rare migratory birds of global significance, it has been included in the list of important international wetlands. Therefore, ecological protection of the Dongting Lake Basin will have a significant impact on the Yangtze River basin and is an considerable part of maintaining ecological and economic stability in the middle and lower reaches of the Yangtze River Basin. Studies have shown that the ecological and environmental quality of the Dongting Lake Basin has fluctuated considerably over the last two decades. Such fluctuations may be closely linked to the climate change, complex land use types and anthropogenic disturbances in the Dongting Lake Basin. As such, studying the ecological and environmental factors in the Dongting Lake Basin holds significant importance [10]. In the present study, the overall trends of climate and extreme climate events in the Dongting Lake Basin over the past four decades were evaluated. The BESS model was applied to simulate the ET and GPP at 47 sites in the Dongting Lake basin, and the impacts of climate factors on ET and GPP within the Dongting Lake Basin were analyzed while eliminating the effects of various climate factors. The mechanisms of various climate factors and extreme climate events on GPP and ET were investigated utilizing monthly-scaledata. Such research deepens the understanding of the ecological response mechanisms to climate change and is vital for the future ecological protection of the Dongting Lake Basin. In this work, two carbon and water cycle indicators, GPP and ET, were selected as eco-hydrological process parameters. The average and extreme climatic conditions of the basin were comprehensively considered. Based on multi-source remote sensing data and the vegetation productivity model, we qualitatively and quantitatively assessed the impacts of temperature and precipitation events on vegetation productivity and ET in the Dongting Lake Basin. The BESS model is an ecological process model, which has a relatively complex structure, a large number of difficult-to-obtain input parameters, and a high sensitivity of simulation results to the input parameters. The BESS model applies remotely sensed data to couple atmospheric and canopy radiative transfer processes, two-leaf photosynthesis, energy balance, and evapotranspiration. The BESS model applies remote sensing data to couple atmospheric and canopy radiative transfer processes, two-leaf photosynthesis, energy balance, and evapotranspiration. The sensitivity of BESS to leaf area index and solar irradiance, the most important variables controlling GPP and ET, was intentionally increased in the model. The study area of this paper is the Dongting Lake Basin, which belongs to the region with extensive vegetation cover. The BESS model was chosen to simulate the eco-hydrological parameters in the Dongting Lake basin. Combined with the time lag analysis of temperature and precipitation events on eco-hydrological parameters, the time lag effect of different climatic factors on eco-hydrological parameters at monthly scales can be quantitatively assessed. It is recommended that the effects of climatic factors on them be taken into account in future model simulations. The specific objectives of the present study were: (1) to analyze the spatial and temporal patterns of long-term temperature, precipitation, extreme climate events, GPP, and ET in the Dongting Lake Basin; (2) to assess the contributions of temperature, precipitation, and radiation to the changes in ET and GPP; and (3) to analyze the effects of extreme climate events on GPP and ET in the Dongting Lake Basin. The results facilitate further understanding of the complex effects of meteorological drivers on the water-carbon cycle in the Dongting Lake Basin and are beneficial for eco-hydrological environmental assessment and water resource management.