Research On Drought Monitoring Of Hebei Province Based On SPOT And NOAA Data

Drought is a natural phenomenon of relative water deficit. The severe droughtinfluences production and life of human society and ecological environment. Drought occursfrequently due to the geographic location of study area, water shortages, less precipitation,much evaporation, high temperature and some human reasons, such as rapid populationgrowth, increased industrial and agricultural water use and ecological environmentdeterioration. This paper used time-series SPOT VEGETATION NDVI data between1998and2007, NOAA data in1999and meteorological data, to analyze the change of vegetationcoverage and drought situation in Hebei province within10years. NDVI, AVI, VCIcalculated from SPOT data and TVDI calculated from NOAA data were used to monitor thedrought of the study area. Meteorological drought indices calculated from10-dayprecipitation, temperature and evaporation data in121stations, including precipitationanomaly percentage, precipitation standardized variables, dryness and relative moisture indexwere used to analyze the level of drought and the range of drought affected. The advantagesand disadvantages of these indices were analyzed. The results showed that using SPOT-VEGETATION NDVI data and NOAA TVDI can accurately monitor level of drought, andusing meteorological drought index to monitoring drought was also feasible. The mainresearch conclusions were as follows:(1) This paper used SPOT data and NOAA data to monitor drought of the research area.The arid area from SPOT data in the last ten-day of May1999was less than the arid areafrom NOAA data in May, which may be related to the research methods.(2) This paper used SPOT VEGATION data from1998to2007in Hebei Province to monitordrought. This paper used AVI, VCI and meteorological data, including precipitation anomalypercentage, precipitation standardized variables, dryness and relative moisture index, todetermine degrees of drought. It provided the theoretical basis for drought early warning anddrought relief in Hebei Province. Different drought indices result in different drought levels.From the analysis of AVI, it was clear that the drought area in Zhangjiakou district was largerand it belonged to light drought in the last ten-day of May,1999. The west of Handan,Xingtai and Shijiazhuang belonged to slight drought. The south of Tangshan belonged to medium drought. From the analysis of VCI, it was clear that most of the area in Zhangjiakoubelonged to medium drought. The east of Cangzhou, the central Tangshan and the south ofQinhuangdao belonged to slight drought.(3) After preprocessing and geometric correction of NOAA remote sensing data in1999, TVDI was calculated using split window algorithm to evaluate drought leveldistribution in Hebei Province in1999. From analysis of the result, the whole of Zhangjiakoubelonged to slight drought. Langfang, Cangzhou and Hengshui district also belonged to slightdrought. The east of Cangzhou belonged to medium drought. The central region of Hebeiprovince belonged to slight drought. The area of drought from NOAA data was larger thanthat from SPOT data.(4) NDVI-Ts feature space constructed from NDVI and land surface temperature basedon NOAA remote sensing data was suitable to monitor large area drought, and it was aneffective index to monitor drought. This method can reduce the interference of vegetation todrought monitoring and thus to improve the accuracy of drought monitoring. From theanalysis of the results, the northwest and southeast of the research area belonged to slightdrought and the drought area was large, which was related to precipitation. Precipitation in1999was the least within these ten years. Soil moisture data from local meteorologicalstations was used to verify TVDI, the results showed that soil moisture was negativelycorrelated to TVDI, which proved that NDVI-Ts method used for drought monitoring andevaluation was reasonable.