Abstract

In surface irrigation, uniformity of longitudinal slope and depth of tillage are very important factors in advance duration time. Inappropriate tillage and land preparation can cause uneven surfaces and non-uniform slopes in fields which is especially important in furrow irrigation due to their influence on advance times. The purpose of this study is to evaluate the effect of non-uniform longitudinal slope due to inappropriate tillage on advance and recession phases in furrow irrigation system, which plays an important role in irrigation uniformity and application efficiency. For this purpose 12 furrows, each 42 m long were made with different longitudinal slopes and a width of 0.6 meter. The number of irrigation was 5 with irrigation interval of 4 days and input discharge of 0.8 lps. Results showed that advance times are very different in furrows especially in the first irrigation and varied from 19min up to 50min. The values for recession time were 9 to 29 min. The results of these five irrigation events indicate that non-uniform slope has significant effect on advance and recession time. Therefore with attention to the water crisis and the need to increase efficiency and uniformity of water distribution in surface irrigation, using modern machinery and paying more attention to accurate preparation of land are necessary in order to obtain uniform furrows in fields.

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