水稻的干旱指标与干旱预报

从作物的干旱机理和水稻节水栽培模式变化的角度，提出并论证了以土壤墒情作为水稻干旱 指标的合理性和可行性，并建立了稻田的水分平衡方程与土壤水分消退模型，确定了研究区域以土壤 墒情作为水稻干旱指标的指标取值和对应的干旱等级划分;同时，提出了以断水天数为指标的水稻干 旱预报新方法。应用表明，该方法适合于安徽江淮丘陵区的自然环境条件和作物生长习性。

DEM-based extraction and analysis of digital river network of Tarim River Basin

Aiming at the extraction and correction of the digital river network in arid and semi-arid areas and taking Tarim River Basin as the study area，the river network of the river basin is extracted with Arc Hydro Tools model on the basis of the AETER GDEM data product with horizontal resolution of 30m，while the sub-basins are divided by taking hydrological station as the outlet section of sub-basin，and then the differences between the extractions of river networks with various types of geomorphological features and the actual statuses are analyzed for the DEM corrections of those areas with larger errors between the extracted river network and the actual statuses based on AGREE algorithm． The result shows that ( 1) the DEM-based extraction of river network has higher accuracy for the mountainous land with larger terrain undulation． For the areas such as hilly and plain region，etc．，errors are even to occur due to the causations of the error from sampling，human activities，etc．，thus the DEM corrections of different degrees must made for different types of geomorphic unit，so as to make the extracted river network consistent with the actual status; ( 2) The extracted result is most consistent with the actual status when the water catchment area threshold is set as 10% of the maximum water catchment accumulation of the sub-basin during extracting the river network; ( 3) From the aspect of the efficiency of the extraction，the extraction efficiency is higher if extracting river network in a river basin by means of DEM and Arc Hydro Tools in combination with DEM correction technique，which is suitable for the basic work of establishing a hydrological model．