【摘要】 选择西藏地区有代表性的 14个站 1961年～ 1998年 5月～ 8月降水量资料 ,采用文献中的旱涝指标 ,对西藏地区初夏旱和盛夏旱基本特征进行了分析 ,结果表明 :初夏旱出现的机率明显多于涝 ,平均 2年～ 3年一遇。盛夏沿江一线、那曲中西部涝的出现机率多于旱 ,平均 5年～ 7年一遇轻旱 ,6年一遇重旱 ;东北部和东南部相反 ,旱多于涝 ,平均 2年一遇旱。从近 40年夏旱发生频率来看 ,80年代为干旱的多发期 ,90年代为初夏旱的低发期 ,60年代为盛夏旱的低发期。在明确夏旱变化规律的基础上 ,提出了有针对性的防御措施。更多还原

【Abstract】 The monthly rainfall data of May to August of 14 stations in Tibet from 1961 to 1998 are used. By using the index of drought/flood from reference document, the climatic character of early summer and midsummer drought are discussed. The results show that the frequency of early summer drought is higher than that of flood in Tibet and the drought occurs every 2~3 years on the average. The frequency of midsummer flood is higher than drought along the Yalung River and in mid western Naqu, the slight drought occure every 5~7 years and heavy drought every 6 years. Otherwise, the chance of midsummer drought is more than flood in southeastern and northeastern Tibet, the drought occurs every 2 years. In the last 40 years, there were more drought during 1980s, but few early summer drought during 1990s and midsummer drought in 1960s. The concept in the rule of drought are made clear, the defensive strategies against the summer drought and different defensive measures are put forward with the aim at high output, fine quality and high efficiency in the production and the sustainable development of agriculture.更多还原