| Global warming is becoming an indisputable truth. To response the global climate change, it is inevitable that the global hydrologic cycle changes at the same time. This change causes the temporal and spatial redistribution of water resource, as well as the change of its mass and quantity. These have some direct or indirect influences to precipitation, runoff, evapotranspiration and etc. These influences could further impact the ecological environment and social and economic development. Global hydrologic cycle, on one hand it is influenced by climate change, on the other hand vice versa.Take the southeast Tibet Yarlung Zangbo River Basin as the research area, which is influenced the most by climate change and caused severe glacier shrink, meanwhile melt water covers its 30-80% runoff, to discuss its glacier & groundwater mass change under the background of climate change and predict its trend in the future, could facilitate us to understand the influences to water resource, ecology and environment by climate change in the southeast Tibet. It could guide us on basin water resource management and policy making, drought and flood disasters, agricultural irrigation, reducing environmental problems. It could also help us to research the response of basin-scale hydro-eco process to the climate change.This research is based on basin water mass balance equation, we use an indirect approach, calculate basin precipitation, evapotranspiration, terrestrial water mass change and runoff these components, and further figure out the glacier & groundwater mass change of Yarlung Zangbo River Basin from 2005 to 2010. And combined with the basin climate from 2011 to 2030 predicted by A2 and B1 scenarios of IPCC SRES(Special Report on Emission Scenarios), we predict the future status of basin glacier & groundwater mass change. We get following main conclusions:1. Using 37 meteorological stations’ monthly mean temperatures and precipitations near Yarlung Zangbo River Basin, through IDW spatial interpolation, we acquire basin spatial precipitation and temperature data, the result shows that the temperature stays a high level during the last 50 years; Using Takahashi formula, with the raster data of the precipitations and temperatures, we calculate the basin monthly evapotranspiration in the ArcMAP software, the result indicates that the annul evapotranspiration of Yarlung Zangbo River Basin is about 250mm without drastic fluctuation.2. With the GRACE (Gravity Recovery and Climate Experiment) data from 2005 to 2010, terrestrial water storage changes of Qinghai-Tibetan Plateau and Yarlung Zangbo River Basin were inversed and systematic analyzed. The result is also compared with hydrologic models CPC, CLM, VIC and precipitation data. The preliminary results indicated a persistent decreasing trend in the yearly terrestrial water storage level with significant fluctuations in seasonal changes for these two study region in recent years, where in Qinghai -Tibetan Plateau the yearly decreasing rate is about 14mm/a (equivalent to about 3.64x109t/a water loss in terrestrial storage), and for Yarlung Zangbo River Basin approximately about 16mm/a (about 3.8×108t/a water loss in terrestrial storage). Comparisons of GRACE based inversions with those simulated by internationally well-known hydrological models suggested the significant discrepancies existed either for yearly or for seasonally terrestrial water storage changes. In general, CPC model simulated quite similar variation treads compared to GRACE reversed but with a smaller fluctuation magnitude. However, both CLM and VIC models released by GLDAS give quite different outputs compared with each other and to the GRACE reversed. The discrepancy is mainly attributed to the shortcomings in ground water variation simulations for the most of hydrological models. Moreover, the complex meteorological, hydrological and the underneath conditions in Qinghai-Tibetan Plateau usually cause in-negligible errors for hydrological simulations. The GRACE result shows a terrestrial water mass decrease from 2009 to 2010, which indirectly reflects the southeast China drought that time. The GRACE result is consistent to the precipitation data, and precipitation peaks 1 or 2 months before GRACE.3. Using our distributed hydrological model ESSI, combined with basin DEM, LULC, soil type and several climate data, we simulate the monthly runoff of Yangcun station from 1998 to 2005. The result indicates its monthly runoff simulation is acceptable. We simulate the monthly runoff of Yarlung Zangbo River Basin from 2005 to 2010.4. With the former data and basin water mass balance equation, we calculate the glacier & groundwater mass change of Yarlung Zangbo River Basin from 2005 to 2010. The result shows a clear decrease of glacier & groundwater mass, its rate is 17mm/a, which is a little faster than terrestrial water mass change, this maybe because the storage of surface water when glacier and groundwater loss. We model the relation between basin glacier & groundwater mass and the climate in a statistic way, and according to the data released by UKMO based on HADCM3 model, we recover the climate status of A2 and B1 scenarios in Yarlung Zangbo River Basin from 2011 to 2030. Then, we combine them with our statistic model, we find that under both scenarios, the glacier & groundwater mass decreases, which we believe mainly caused by the increases of both temperature and precipitation there. |
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