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延安地区位于西北黄土高原丘陵沟壑地带,百分之九十五以上是原、坡旱地。主产作物是小麦、谷糜、豆类、高粱等。本区气候属大陆性干旱高原类型,常年降水量在510～680毫米之间,一般可满足作物生长的需要。但降雨分布不均,冬春少,夏秋多。春季降水仅占年总降雨量的13～19%,因此春旱频繁。夏季降水约占全年雨量的49～56%,黄龙一带在340毫米以上,洛川、延安在300～320毫米之间,而北部吴旗、志丹一带仅为250毫米。总体来看,雨量是从南往北减少,东部黄河沿岸较西部同纬度的志丹等地稍多,因而东南部及黄河
Yan’an region is located in the hilly areas of Northwest Loess Plateau, more than 95% of the original slope slope. The main crops are wheat, glutinous rice, beans, sorghum and so on. The climate in this area belongs to the continental arid plateau type. The annual precipitation is between 510 and 680 mm, which generally meets the needs of crop growth. However, uneven rainfall distribution, less winter and spring, summer and more. Spring rainfall accounts for only 13-19% of annual total rainfall, so spring drought frequently. Summer precipitation accounts for 49- 56% of the annual rainfall, Huanglong area is above 340mm, Luochuan and Yan’an are between 300 and 320mm, while northern Wuqi and Zhidan areas are only 250mm. Overall, rainfall decreased from south to north, and the east coast of the Yellow River was slightly more than Zhidan at the same latitude in the west. Thus, the southeastern part of the Yellow River