Abstract:
Abstract: The suitable ratio of canal to well in the combined well-canal irrigation area can contribute to safety of groundwater environment and sustainable regional agriculture production. In order to investigate the influence of canal-to-well ratio on regional soil salinity accumulation, dynamics of groundwater depth, and groundwater hydrochemical characteristics in combined well-canal irrigation area, this study was carried out in a typical area in the People's Victory Canal area in China. The agriculture water consumption and precipitation in the People's Victory Canal area from 1954 to 2014 were collected, and the canal-to-well ratio, dynamics of groundwater depth and hydrochemical characteristics of groundwater from 2008 to 2014 in the research area were analyzed. The relationships between precipitation, groundwater depth, groundwater hydrochemical characteristics and the canal-to-well ratio were explored. The results indicated that there was a significant positive correlation between canal-to-well ratio and annual precipitation in research area (P<0.05). The variation coefficient of groundwater depth in the upstream of branch canals was higher than that of downstream of branch canals. Accumulated variation in soil electrical conductivity at 0-100 cm depth of 2nd branch canal was less than that of 1st branch canal and 3rd branch canal by 4.77% and 5.55%, respectively. Compared with the year of 2013, the area of groundwater depth greater than 11 m in 1st branch canal, 2nd branch canal and 3rd branch canal during the wintering period of winter wheat in 2014 was increased by 31.78%, 25.07% and 40.81%, respectively. When the water consumption amount and method were same, the high canal-to-well ratio can result in a small increase of area with groundwater depth beyond 11 m, indicating that the high canal-to-well ratio can alleviate the deterioration of groundwater depth. Alkaline trend of groundwater during dry and normal seasons in the research area was obvious owing to unrestrained groundwater exploitation. Affected by climate change, the reduction of precipitation in the combined well-canal irrigation area was obvious. Meanwhile, average irrigation amount by canal in the past 5 years was 2.90×108 cm3, accounting for 75.52% of mean annual irrigation amount. On the other hand, ground water overdraft in the research area would be remained in order to ensure agricultural sustainable production, which would be bound to aggravate alkaline trend of groundwater and expand the range of deep groundwater zone. It could be concluded that the suitable ratio of canal to wells decreased the groundwater exploitation and alleviated the alkaline trend of groundwater environment, moreover, maintained the reasonable groundwater depth.