Surface irrigation has been predominantly used for field crops in agriculture area to boost agricultural yields and outputs, however, this may also raise groundwater tables, salinize soils and reduce water quality due to poor irrigation management. Therefore, it is essential for requiring a better understanding of the hydrologic mechanisms related to soil water fluxes (e.g., evaporation, transpiration, infiltration, deep percolation and groundwater capillary rise) by surface irrigation. This study investigated the impact of surface irrigation on soil water movement and recharge to groundwater in the Yellow River irrigation area of Yinchuan Plain, China. Combining comprehensive filed observation and stable isotopic techniques, we described the soil water mechanism under two land covers (bare ground or maize) in 2019 and 2020. The soil depths affected by precipitation infiltration and evaporation were mainly 0-50 cm, while the soil influenced by irrigation was the entire profile in the mode of piston flow. According to soil water potential variation from 70 to 100 cm, we conclude that the maize root took up the soil water up to the depth of 100 cm during the tasseling period. The infiltration and capillary rise in 2020 were similar with those in 2019. However, the total deep percolation was 156.6 mm in 2020 which was smaller than that in 2019 because of the maize root water uptake. The leakage of ditch was the major recharge resource of groundwater for the fast water table rise. This study is critical for agricultural water management to improve irrigation efficiency and water use efficiency in arid regions.

Studying soil water dynamics and water balance on coral islands is important to utilize and manage the limited freshwater resources of these islands. In this study, we investigated the soil water dynamics of Zhaoshu Island, Xisha Archipelago, using observed data and the Richards equation and analyzed the water balance of this island from October 2018 to September 2019. We found a dry soil layer at depths between 40 cm and 160 cm of the soil profile from November 2018 to April 2019 (dry season) which prevented the exchange of water between upper soil layers and groundwater. Therefore, the vegetation developed deep roots to take up water from the groundwater. Precipitation is the only source of the freshwater, while approximately 38% of the precipitation infiltrated into the groundwater, 22% of the precipitation was taken up by vegetation, and 39% of the precipitation evaporated from the land surface during the entire observed year. In the dry season, evapotranspiration (ETa) was only 44 mm/month, which was 94% greater than the amount of precipitation, and approximately 14 mm/month of water was taken up from the groundwater by plants. However, in wet season, infiltration dominated the processes of soil water movement. Approximately 56% of the precipitation infiltrated into the groundwater and 37% of the precipitation was consumed by ETa. This study can help us to better understand the process of water movement on coral islands and provide references for further management to protect coral island ecology.

Studying soil water dynamics and water balance on coral islands is important to utilize and manage the limited freshwater resources of these islands. In this study, we investigated the soil water dynamics of Zhaoshu Island, Xisha Archipelago, using observed data and the Richards equation and analyzed the water balance of this island from October 2018 to September 2019. The precipitation, the water change values in the entire flow domain (△Volume), the bottom boundary flux (vBot), transpiration (Er), and evaporation (Es) during the entire observed year were 913 mm, 10 mm, 349 mm, 203 mm, and 351 mm, respectively. Precipitation is the only source of the freshwater, while approximately 38% of the precipitation infiltrated into the groundwater, 22% of the precipitation was taken up by vegetation, and 39% of the precipitation evaporated from the land surface. From November 2018 to April 2019 (dry season), there was a dry soil layer at depths between 40 cm and 160 cm in the soil profile. Evapotranspiration (ETa) was only 44 mm/month, which was 94% greater than the amount of precipitation, and approximately 14 mm/month of water was taken up from the groundwater by plants. However, in wet season, infiltration dominated the processes of soil water movement. Approximately 56% of the precipitation infiltrated into the groundwater and 37% of the precipitation was consumed by ETa. This study can help us to better understand the process of water movement on coral islands and provide references for further management to protect coral island ecology.

Study of the soil water dynamic and water balance in coral islands is important to utilize and manage the limited freshwater resources of islands. In this study, we studied the soil water dynamic in Zhaoshu Island, Xisha archipelago using the observed data and the Richards equation, and analyzed the water balance of this island in the dry and wet seasons, respectively. The soil water movement showed that there was a dry soil layer at the depths between 40cm and 160cm of the soil profile in the dry season. The evaporation (Es) flux was low, but the transpiration (Er) could still absorb water from the capillary zone to maintain growth. In the wet season, the infiltration dominated the main process of soil water movement. The result of water balance showed the precipitation, the change values of water in the entire flow domain (△Volume), bottom boundary flux (vBot), Er, Es were 913mm, 10mm, 349mm, 203mm, 351mm, respectively from October 2018 to September 2019. Precipitation is the only source of the freshwater, about 38% of the precipitation infiltrated into the groundwater, 22% of the precipitation was uptaken by the vegetation, and 39% of the precipitation was evaporated from the land surface. In the dry season, the evapotranspiration (ETa) was just 44mm/month which was 94% larger than the precipitation, and about 14mm/month of water was uptaken from groundwater by the plants. But in the wet season, 56% of the precipitation infiltrated into the groundwater, 37% of the precipitation was consumed by ETa. This study can help us well understand the process of water movement in coral islands, and provide references for further management in protecting coral island ecologies.