Estimation Of Evapotranspriation Using RS In Jinci Spring Area And Regional Water Balance Analysis

Jinci Spring Area is located in the arid-semi-arid climate zone, of whichwith uneven spatial and temporal distribution of precipitation, the surfacewater quality is poor. Karst groundwater is the main source of water supply.Because of vegetation have good coverage condition, surfaceevapotranspiration is not only one of the major channels of water resourceexcretion, but also an important factor to the regional water balance. Therefore,it is of great significance to rational development and utilization of local waterresources and ecological environment protection by studying on calculation ofsurface evapotranspiration and analyzing on spatial and temporal variationcharacteristics and influencing factors.The surface evapotranspiration variation from2008to2012is estimatedby using surface energy balance principle and applying quantitative inversionmodel-SEBS evapotranspiration model based on Remote Sensing (RS) inJinci Spring Area. Analysing the dynamic characteristics and the spatialdistribution of land surface evapotranspiration, investigating the relationshipbetween land surface evapotranspiration and meteorological factors(precipitation, temperature), topographical factors (elevation, aspect, slope), land cover types, vegetation cover types (NDVI).The whole article analyzedJinci Spring Area water balance on the survey of the elements of waterbalance.The five years’ timing variations of Jinci Spring Area surfaceevapotranspiration from2008to2012shows that:(1) Interannual variation ofsurface evapotranspiration ranged small.(2) The distribution of years surfaceevapotranspiration was "unimodal" type, maximum from July to August, andminimum on December, January and April;(3) The meteorological factors onthe surface evapotranspiration worked mainly through changes in precipitationand temperature. The study shows changes in surface temperature andevapotranspiration synchronized generally, and were significantly correlated.The complx analysis on surface evapotranspiration, DEM data, land covertype, and normalized difference vegetation index (NDVI) together with GISreveals the relationship between Jinci Spring Area surface evapotranspiration,topographical factors, land cover type and NDVI.(1) The studied areaevapotranspiration increases with elevation increase. Evapotranspirationrelatively is strong on westward slope, and slight on northward slope. And itpeaks at40°slope;(2) Surface evapotranspiration and land cover types areclosely related. The region evapotranspiration by forest covered is followed byshrubs and grass covered region, and the smallest are cities and farmland.(3)When NDVI is between0to0.32, surface evapotranspiration increases with NDVI increases, when between0.32to0.6, it decreases with NDVI increasing,when NDVI more than0.6, it increases again.The study analyzed various elements of Jinci Spring area karst watersystem by utilizing the principle of water balance, and checked rainfallinfiltration coefficients. The result shows that from2008to2012karst watersystem was a positive balance, and groundwater levels rose. This conclusion isconsistent with the monitoring results from jinci seismic karst water long viewhole.