地理科学 ›› 1987, Vol. 7 ›› Issue (4): 316-325.doi: 10.13249/j.cnki.sgs.1987.04.316

• 论文 • 上一篇    下一篇

西北黄土高原区农业干旱特性的初步分析

阚贵生, 孙荣强, 耿雷华   

  1. 水电部南京水文研究所
  • 出版日期:1987-07-20 发布日期:1987-07-20

A PRIMARY STUDY OF AGRICULTURAL DROUGHT IN THE LOESS PLATEAU AREA

Kan Guisheng, Sun Ronqian, Geng Leihua   

  1. Nanjing Hydrology Research Institute
  • Online:1987-07-20 Published:1987-07-20

摘要: 西北黄土高原泛指陕、甘秦岭以北,内蒙阴山以南,宁夏贺兰山、青海日月山以东,山西太行山以西的广大地区,土地资源丰富,为我国主要农业地区之一。然而本区气候干旱,降水稀少,水资源主要为黄河及其支流,蕴藏量较少,开发利用也比较困难。多年平均雨量由西部的200mm向东渐增至600mm,其中70-80%集中于7-9月,并多以暴雨和雷阵雨形式出现,补给土壤的有效降水很少。如陕北绥德、米脂一带梁峁区,在约450mm的降水中,仅有27%对土壤水份有较大的补给作用。降水在年际间的分配也不均匀,以榆林地区为例,多年平均雨量438mm,而有些年份少则100mm,多则900mm以上。

Abstract: The dry-day sequences (days) and number of wet-days in a year and growing seasons (April to September) are used to analyse the relations between precipitation and agricultural drought without irrigated condition, and the characteristics of annual drought variations and variations in a year in the Loess Plateau area, The significative result is obtained. In addition, the run theory is used to study drought, probability equation p= pK-1(1-p) is derived from the probability mass function of run-length f(k)= qpK-1, in which P is the probability of obtaining a sequence of k-day dry-days and p is the distribution parameters and also the conditional probability of a dry-day following a dry-day. It can be obtained from the observed data and the following equation where s1 is the total number of dry-day sequences of various lengths. Both of P and p show the stochastic characteristics of drought and distinct regional objective law of distribution in the Loess Plateau area.