北京地处华北平原西北边缘，西北部被群山环抱，山岭连绵，形成天然屏障，东南部为平川，与华北大平原相接，这就形成了我市干旱少雨的地形条件。据新中国成立前５８０年史料记载（１３６８～１９４８年），共发生较大旱灾４０７次，基本上是三年２次。新中国成立以来，我市修 Beijing is located on the northwestern edge of the North China Plain. The northwestern part is surrounded by mountains and mountains. The mountains form a natural barrier. The southeastern part is a plain and connects with the Great Plains of North China. This forms arid and rainy terrain in our city. According to the 580-year historical records of the former China (1368-1948) before the founding of new China, a total of 407 major droughts have occurred, basically two times in three years. Since the founding of new China, our city repair