SATELLITE DATA AND HYDROLOGICAL MODEL TO ASSES WATER QUANTITY AND QUALITY IN THE YANGTZE RIVER BASIN

摘要

The main objective of the project is to assess waterrnquantity and quality for the Yangtze River basinrnthrough remote sensing data and a distributedrnhydrological model. The paper provides an overviewrnof the project activities that are supported by severalrnpeer review articles to which we refer for details.rnWater quantity analyses are assed with the fullyrndistributed hydrological model FEST-EWB. The modelrnalgorithm solves the system of energy and massrnbalances in terms of a representative equilibriumrntemperature (RET) that is the land surface temperaturernthat closes the energy balance equation and so governsrnthe fluxes of energy and mass over the basin domain.rnThis equilibrium surface temperature, which is arncritical model state variable, is comparable to LST asrnretrieved from operational remote sensing datarn(MODIS) which is used for the calibration of soil andrnvegetation parameters. The effects on river dischargernof the Three Gorges dam, the largest hydropowerrnproject in the world is evaluated. Observed flowrnduration curves, for the four available river crossrnsections, will be evaluated and compared to FESTEWBrnsimulated flow duration curves as well asrnobserved as simulated hydrographs.rnThe dynamic of the three large lakes (Poyang,rnDongting and Taihu), which change considerably theirrnarea during the seasons, will also be analyzed usingrnMERIS and ASAR data to infer surface area changesrnand LEGOS altimetry data (Topex/Poseidon, Jason,rnENVISAT) for water level. Data from 2003 to 2006rnare evaluated.rnFEST-EWB is run in for the whole Yangtze Riverrnbasin at spatial resolution of 0.05° and temporalrnresolution of 3 hours. Results are provided in terms ofrnhourly evapotranspiration, soil moisture and landrnsurface temperature maps for the period between 2003rnto 2006 and flood hydrographs at different river crossrnsections.rnWater quality analyses are performed along thernYangtze river estimating turbidity and suspended solidrnsediments from MERIS (250 m) and MODIS (300 m)rndata using different algorithms. Two main objective arernidentified: i) to evaluate parameters seasonal andrnyearly variations and hence, their correlations to riverrndischarges and precipitation events; ii) to quantify therneffect of Three Gorges dam and how its flowrnregulation affects the sediment transport downstream.rnThe years 2002, 2004 and 2006 were selected asrnparticular periods: the first one is before the ThreernGorges Reservoir impoundment, the second one isrncharacterized by severe floods, while the last one is arndry year.