黄土高原半干旱区集水农业的气候学初探──以甘肃黄土高原半干旱区为例

水分不足是限制黄土高原半干旱区旱地农田生产力的主要因素。通过对甘肃黄土高原半干旱区自然降水和土壤水分等农业气候因子的动态分析，发现５、６月间降水低谷与７—９月丰水季交替重复出现是本区正常的天气现象。这一降水低谷引起土壤水分低值槽现象，造成夏粮作物的“卡脖旱”，严重影响产量。在该区发展集水农业，雨季蓄集雨水，于次年５、６月间干旱季节进行补偿性灌溉，既可充分利用雨季雨水，又可消除土壤水分低值槽现象，达到增产目的。因此，从气候学角度讲，在黄土高原半干旱区实行集水农业是必要而可行的。

CLIMATIC STUDY ON WATER HARVESTING AGRICULTURE IN THE SEMIARID REGION OF LOESS PLATEAU──A Case Study on the Semiarid Region of Gansu Loess Plateau

Insufficient water is the main factor to limit the field productivity of dry land in the semiarid region of Loess Plateau. By means of analysis on the natural precipitation and soil water, We concluded: it is a normal climatic phenomenon that the precipitation valley in May-June alternates with the peak from June to Septimber.This precipitation valley leads to the low value of soil water, which usually results in the critical drought of summer crops, and reduces the yield. Harvesting rainfalls in the rainy season, and irrigating in the next May-June, can fully utilize the rainfalls as well as eliminate the valley of soil water, thus increases the yield. Therefore, in terms of climatic theory, to develop water harvesting agriculture is necessary and feasible in the semiarid region of the Loess Plateau.