Abstract
Canal lining is commonly used to reduce seepage loss and increase water use efficiency. However, few studies have quantitatively estimated the seepage control effects of different lining materials under different service times. Ponding tests were conducted on the same canal section with four different lining statuses to investigate the canal lining effect on seepage control and its impact factors in arid areas. The cracks and holes in different lining materials were surveyed, and the canal seepage rates under the four test treatments were calculated by monitoring the water level change in the canal. The results show that the cracks in the joints of the two precast concrete slabs and holes in the geomembrane, which are located 0.25 m above the canal bottom on two sides of the canal, are responsible for the increased seepage loss. The new concrete and geomembrane lining combination reduces seepage by 86% compared with no lining, while seepage can be reduced by 68% using the concrete and geomembrane lining combination after three service years, and the amount decreases to 11% by using geomembrane lining with a three year service time. Based on the experiment and literature, a statistical relationship between the seepage reduction and lining service time was established, which provided a possible and easy way to estimate seepage losses from lined canals and improve the estimation accuracy using an empirical formula. Without considering the service time lining effect, the seepage loss is underestimated by 58%, and the canal water use efficiency is overestimated.
Highlights
In the past several decades, it has been a great challenge to maintain the sustainable use of water resources, especially in arid and semi-arid regions, due to increasing irrigation demands and climate change [1,2,3]
The reduction factor β in the T1 treatment was 0.32, which means that the combination of concrete and geomembrane lining with a service time of three years can still reduce seepage loss by 68% compared with the unlined T3 treatment
This study investigated the relationship between the seepage control effect change in the canal lining and service time by ponding tests
Summary
In the past several decades, it has been a great challenge to maintain the sustainable use of water resources, especially in arid and semi-arid regions, due to increasing irrigation demands and climate change [1,2,3]. It is necessary to investigate the lining effect on controlling seepage loss to accurately estimate the agricultural water use efficiency and proper management of irrigation systems, effective irrigation plans, and irrigation project construction [21] Many materials, such as geomembrane, bitumen, masonry, and concrete, have been reported in the literature to reduce seepage loss in canal lining [22,23,24]. Even fewer studies have investigated the change in the permeability of lining material with time and its relationship with the change in cracks or holes in the lining materials, which is important for quantitatively estimating the seepage control effect of lining canals under different service times. This study investigated the seepage control effect change in the lining canal with service time and its relationship with the distribution of cracks and holes in lining materials. The seepage control reduction factor with the service time was estimated by a simple linear formula, which can be used to help calculate the water efficiency of the lined canal system after a specified service time
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