Optimization of Winter Irrigation under Freeze–Thaw Conditions: A Case Study of the Yellow River Delta, China

Optimal winter irrigation may be an alternative method for controlling soil salinization under seasonal freezing and thawing conditions in the Yellow River Delta. However, few studies have focused on optimal based dynamics of water, heat, salt during freezing–thawing period this region. Taking seedling stage wheat Delta as research object using observation data hydrothermal from Shandong agricultural high-tech demonstration base 17 October 2019 to 15 June 2021, a numerical simulation coupling process freeze–thaw experimental area was carried out through Simultaneous Heat Water Model (SHAW). The results model were evaluated according mean error (ME), root square (RMSE), Nash efficiency coefficient (NSE). showed that SHAW can well simulate moisture (SM), temperature, growth region: SM at depth 0–80 cm with ME < 0.038 cm3 cm−3, RMSE 0.064 NSE > 0.669; temperature 1.311 °C, 1.493 0.738; salinity 0.005 g kg−1, 0.014 0.607. Moreover, used distribution water different methods wet, normal, dry years. It suggested appropriate amount 80 mm wet years normal 100 years, which could beneficial stage. These provide reference optimization other similar areas.