Hydrus-1D model for simulating water flow through paddy soils under alternate wetting and drying irrigation practice

Modelling Projected Changes in Soil Water Budget in Coastal Kenya under Different Long-Term Climate Change Scenarios

“…The HYDRUS-1D model was used to simulate infiltration in homogeneous soils, with arbitrary initial water content distributions, subjected to unsteady rainfall, and under the free bottom draining condition to measure deep percolation rate. HYDRUS-1D has been used successfully in numerous studies, providing a good validation of its functionality to model deep percolation [6,[70][71][72][73]. Ma et al (2010) [58] further found that the results obtained from the HYDRUS-1D model for cumulative deep percolation were closer to observed results that other models.…”

Estimation of evapotranspiration for paddy under alternate wetting and drying irrigation practice*

“…Shekhar et al . (2019) observed no significant grain yield under mild soil water stress (450 mb) and about 12% yield reduction under severe soil water stress (700 mb) with 23–28% irrigation water saving. Furthermore, irrigation water saving was increased to 38–41% when AWD was practised for a drought‐resistant rice variety, which resulted in the same yield as conventional irrigation practice (Xu et al ., 2015).…”

“…Of this, about 20–50% of water is utilized for crop production and the rest is lost from rice fields through runoff and percolation (Bouman and Tuong, 2001; Tan et al ., 2014). The above‐mentioned losses can potentially be reduced by adopting some of the best water management practices such as a system of rice intensification (Sinha and Talati, 2007), bund plugging (Patil and Das, 2013) and alternate wetting and drying (Shekhar et al ., 2017).…”

“…The alternate wetting and drying (AWD) irrigation technique involves allowing ponding water to be depleted below a certain depth of soil, which is monitored through a field water pipe (a perforated pipe) or tensiometer. Many researchers have reported that the rice field can be left without irrigation for 4–18 days if the AWD irrigation technique is practised (Bouman et al ., 2007; Lampayan et al ., 2015a; Shekhar et al ., 2019).…”

“…Therefore, the soil water stress coefficient ( K S ) must be considered when calculating ET C under AWD irrigation practice. In conventional irrigation practice, K S will be equal to 1 and starts to decrease under AWD irrigation practice (Shekhar et al ., 2019). The Food and Agriculture Organization (FAO) have also documented that ET C depends on soil and crop type, plant growth, salinity, water and nutrition application or stress, etc.…”