Statistical Analysis of Conveyance Efficiency in Semi-Elliptical Prefabricated Canalets and Earth Canals

Background and Objectives
In order to use water efficiently in agriculture, it is necessary to know the amount of water leakage from canals. In this study, evaluation of earthen canals and canals of irrigation and drainage networks of Khuzestan province was performed by calculating water distribution efficiency.The traditional method of conveyancing agricultural water from the extraction point to the farm is using earthen canals, which, although low initial cost, due to the need for short-term dredging and weed clearing, has a high maintenance cost and most importantly water losses, which sometimes reaching up to 70% (Ghobadian and Khalaj 2012). The average water transfer efficiency in 40 canals in Moghan Agro-Industrial Zone, in the canals related to Agro-Industrial lands, channel A and return channel A, were equal to 87.7, 90.9 and 86.8%, respectively. The average waiting time of farmers was 30 minutes per kilometer and land losses were set at 35 square meters per hectare (Akhavan and Abbasi 2013). Therefore, the lack of sufficient studies led to the statistical analysis of distribution efficiency in canals and earthen canals in Khuzestan province to be evaluated in a research project.
Methodology
The present study was conducted based on the results of field visits and data collection from different locations of modern distribution networks including tertiary and fourth degree channels as well as the traditional water distribution irrigation network in the cities of Khuzestan province in 2017. In this method, two consecutive sections of semi-elliptical prefabricated canalets and earthen canal were selected. According to the current cross-sectional conditions, the flow velocity was measured. The flow velocity measurement was performed using propeller current meter device in each section and finally the flow rate of two input and output sections was calculated. In this study, 29 canals including 17 tertiary and fourth degree channels and 12 tertiary and fourth degree earthen channels were evaluated. 16 canals were covered by irrigation and drainage networks of Khuzestan and one canal in Baghmalek city was under the management of farmer. Six earthen canals under the management of farmers and six other tertiary and fourth degree earthen channels were covered by
Statistical Analysis of Conveyance irrigation and drainage networks in Khuzestan province. One-way analysis of variance was performed with SPSS16 software. To compare the numbers of distribution efficiency indices (percent), it is necessary to eliminate the scale difference. Therefore, the standard Z-Score standardization method was used to resolve the scale difference. 
Findings
The lowest and highest distribution efficiencies were calculated at 46.88 and 99.69% in Baghmalek and Shushtar counties. The average distribution efficiency in all studied channels was 79.75%. The results of variance analysis of distribution efficiency means showed that there was a significant difference between the distribution efficiency means in semi-elliptical prefabricated canalets, personal canals, non-personal semi-elliptical prefabricated canalets and erathen canals at the level of 5%. The average distribution efficiencies in canals and earthen canals were 86.47 and 70.23%, respectively. The lowest average distribution efficiency in the dedicated channel (under farmer management) was 46.88% and the highest distribution efficiency in the non-dedicated channel was 99.67%. The Z-Score proportions calculated for the distribution efficiency based on the type of construction material showed that 72.1% of the semi-elliptical prefabricated canalets were in acceptable condition, while this rate was only 9.1% in the earth channels. All grade 4 channels had acceptable distribution efficiencies. 59.1% of non-specific channels (under the cover of irrigation and drainage networks of Khuzestan) had acceptable distribution efficiency while 85.7% of specific channels did not have acceptable distribution efficiency.
Conclusion
In this study, the values ​​of distribution efficiency calculated in different canals showed that the type of ownership of canal is effective in increasing the distribution efficiency. In a way the average distribution efficiency in the canals covered by irrigation and drainage networks as non-personal channels were significantly different from the channels managed by the farmer (private channels) at the level of 5%. Scientific management performed by irrigation and drainage networks in Khuzestan province caused about 60% of non- private water distribution channels to have acceptable irrigation efficiency, while the lack of sientific management on personal canals (under farmer management) including non-volume delivery of water due to mismanagement masurrement structures has caused about 85% of channels under farmer management do not have acceptable distribution efficiency.By delivering a volume of water through personal channels to the operator, it increases the distribution efficiency in the channels under farmer management.