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University of Tsukuba (2011)

Study of Ecohydrological Responses to Global Warming and Grazing Pressure Changes in Mongolian Semi-arid Region

BYAMBAKHUU Ishgaldan

Titre : Study of Ecohydrological Responses to Global Warming and Grazing Pressure Changes in Mongolian Semi-arid Region

Auteur : BYAMBAKHUU Ishgaldan

Université de soutenance : University of Tsukuba

Grade : Doctor of Philosophy in Science 2011

Résumé partiel
In this study we present a simple coupled modeling framework for studying ecohydrological processes by investigating them at two distinctive surface conditions (nongrazing and grazing, in which nongrazing condition was obtained by a fence exclosure experiment). The coupled model consists of the century ecosystem model (version 4) and the TOPLATS hydrological model. The two models were directly coupled through a one-way data transfer method, which was used to simulate the carbon cycle, hydrological cycle and energy fluxes between vegetation, soils, and the atmosphere. On one side of the interface, century ecosystem model simulated the monthly ecological components and evapotranspiration. On the other side, TOPLATS hydrological model estimated hourly hydrological components together with energy fluxes. As a validation of this modeling framework, we performed a 4-year simulation with each model at point scale using field measurement datasets of the study areas. The data in this study were obtained in Kherlen river basin (39400 km2 ) in Mongolian steppe region during RAISE (Rangeland Atmosphere-Hydrosphere-Biosphere Interaction Study Experiment in Northeastern Asia) project campaign between 2003 and 2006. Also we run the century ecosystem model and TOPLATS hydrological model at spatial scale within a Kherlen river watershed with 1 x 1 km resolution. Consequently, this coupled environmental modeling system produced estimates of ecohydrological components at point and spatial scale. For future simulation of ecohydrological components, we applied the downscaled future projection of A2 scenario of IPCC by the regional climate model (Terrestrial Environment Research Center - Regional Atmospheric Modeling System (TERC - RAMS)). The future projection of ecohydrological components and their processes in this study area were performed based on four grazing pressure change scenarios (GP1-GP4), one climate change scenario (GW) and four grazing + climate change scenarios (GWP1-GWP4). The application and validation of century ecosystem model and TOPLATS hydrological model showed that they were equally applicable for both surface conditions at point and spatial scale to simulate ecohydrological components and their processes in Mongolian semi-arid region. Our coupled modeling approach simulated energy and hydrological components well which can be used for future projection estimation in this region.

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