Impacts of agricultural water saving practice on regional groundwater and water consumption in an arid region with shallow groundwater

Abstract

Irrigation is important to agricultural production and can induce changes in the regional hydrological cycle. In particular, in areas with shallow groundwater, fluctuation of groundwater levels will be present with irrigation events and groundwater evaporation. To deal with the shortage of water resources, agricultural water saving (AWS) has been conducted in arid and semiarid area. The Jiefangzha irrigation district was selected as the study area to investigate groundwater dynamics in response to AWS. With the abundant various data, the trend of groundwater level change from 1980 to 2013 was evaluated based on geographic information systems. Groundwater net consumption (ETng) and regional evapotranspiration (ET) during crop growth period were estimated by water fluctuation method and the water balance method. The results indicate that the groundwater depth was relatively stable before 2002, remaining at around 1.7 m. Due to reduction of the water diversion from the Yellow River and the implementation of water saving measures (WSMs), the canal seepage and irrigation infiltration declined, leading to groundwater levels declining by 0.4 m in recent 10 years. Groundwater net consumption of crop growth period was estimated since 1990 and increased from 50 mm/year in 1990 to 110 mm/year in 2013 with the reduction of water diversion. At the same time, regional evapotranspiration has shown a slightly decreasing trend. Thus, the contribution of groundwater to regional evapotranspiration has an obvious increasing trend, accounting for 20 % in 2013, which is doubled compared with that in 1980. Groundwater is very important to sustain crop production and healthy ecology, and it is quite essential to consider groundwater response to regional WSMs and water management.