清代陇东地区干旱灾害初步研究

Drought disasters in the Longdong region in the Qing Dynasty

通过对历史文献资料的搜集、整理、分析,对清代陇东地区干旱灾害的等级序列、时间和空间特征及其成因进行了研究。结果表明:陇东地区自1644年清世祖顺治元年至1912年中华民国元年的268年中,共发生干旱灾害111次,平均每2.4年发生1次;清代陇东地区中度旱灾发生最多,其次为大旱灾和轻度旱灾,而特大旱灾发生最少;从清代早期到中期再到晚期,干旱灾害呈现由少变多又变少的趋势,具有显著波动变化特征;干旱灾害年际间连发性强,2年连发次数最多,7年以上连发造成的危害比较严重。该区旱灾具有明显的季节性特征,以夏旱最多,冬旱和春旱最少,春夏连旱的次数也较多;旱灾具有明显的空间差异性,西南部旱情较重,东北部旱情相对较轻;诱发陇东地区干旱灾害的自然因素主要是由于其独特的地理、地貌环境及气候水文条件,而人类活动即对自然环境不合理的开发和利用也起到了一定作用。清代轻度旱灾和中度旱灾主要是由降水量年内分配不均造成的,大旱灾与特大旱灾主要是由气候干冷导致降水量明显减少引起的。

Through the historical documentaion of the collection、arrangement and analysis,time-space characteristics、disaster grade and the cause of drought disasters in the Longdong region in the Qing Dynasty were researched.The results showed that from 1644（kiyoyo progenitor junji primary era） to 1912（the republic of china primary era）,there were 111 times drought disasters during 268 years in the Longdong region.It occurred once every 2.4 years.The moderate drought happened the most frequently,the strongest drought and the mild drought took the second place.Serious drought were the least frequent to happen.From early period of Qing Dynasty to middle period and then to late period,drought disasters showed trend of few-more-few and showed significant fluctuations.Yearly droughts occurred obvionsly.Though the highest number of repeating was two-years,seven-years or more caused serious harm.There was obvious seasonal characteristics of drought in this area：summer drought was the most,dry winter and spring drought was the least,moreover,the number of spring and summer drought was also more.Drought had obvious spatial differences：the drought was heavy in south-west,north-east of the drought was relatively minor.Drought-induced disasters were mainly due to the natural factors of climate change,the special geographic location and unequal distribution of precipitation.However,irrational human activities,namely,the development and utilization of the natural environment also played a role.The mild and moderate drought disasters were caused by uneven distribution of rainfall during the years.The great and severest drought disasters generally was caused by significantly decrease of rainfall with dry and cold climate.