Studies on the Effective Rainfall of Upland Irrigation Design Water Requirement

旱地灌溉需水量的多少是重新考虑旱地灌溉实践观点的必要条件，特别是在日本这样的湿润地区。本研究探讨了旱地灌溉需水量与试验农田和旱地灌溉有效降雨量的关系。研究结果总结如下：1。在适当的灌溉水量条件下，厚木中心试验农场的灌溉效果得到了认可。但在滴灌试验场，由于降水的增加，出现了过灌现象。需水量与作物种类、季节和有效降雨量有关。有效降雨量对旱地灌溉需水量的影响较小。因为很难预测降水和控制通过取水设施取水。本研究的解决方法是采用统计方法计算有效降雨量，利用降水资料计算旱地灌区实际有效降雨量的关系。而在规划时被认为无效的那一小部分降雨，对土壤水分的增加是有用的，是有效降雨的一部分。滴灌系统在节水和增加有效降雨量方面发挥了重要作用。如果采用本研究的方法，可以预期灌溉需水量的减少计划。这样就可以在水源少的农村进行耕作。

The amount of upland irrigation water requirement was necessary to reconsideration viewpoint of practice upland irrigation, in humid region like Japan.This study examines about relationships between upland irrigation water requirement and the effective rainfall, of the experimental farm and upland irrigation field.The results are summarized as follows :1. The irrigation effect was admitted at proper irrigation water quantity at the Atsugi Central Experimental farm. But it happened that over irrigation, by increase of precipitation at the drip irrigation test farm.2. The quantity of water use was dependent on kind of crops, season and effective rainfall. But amount of effective rainfall was little influenced for amount of upland irrigation water requirement.Because it was difficult to presume of precipitation and to control of water taken through intake facilities.3. The settlement method of this study was calculation of effective rainfall by take statistics, and the relationships of practice effective rainfall at the upland irrigation area from precipitation data. And the small portion of rainfall, which was considered ineffective at the planning time, is useful for increase of soil moisture and admitted for effective rainfall. And the drip irrigation system had been useful in saving water and increase of effective rainfall.4. If this study's methods are recommended in used, the reduction plan of irrigation water demand may be expected. Then it is possible to cultivation at the little water source rural.