Seawater intrusion dynamic at the Casetta farmland (Venice). Characterization using HYDRUS-1D

2020 ◽  
Author(s):  
Greta Finco ◽  
Ester Zancanaro ◽  
Pietro Teatini ◽  
Francesco Morari
Keyword(s):  
Electrical Conductivity ◽  
Solute Transport ◽  
Water Table ◽  
Water Uptake ◽  
Seawater Intrusion ◽  
Root Water Uptake ◽  
Variable Boundary ◽  
Soil Hydraulic ◽  
Hydrus 1D ◽  
Monitoring Stations

<p>Soil and groundwater salinization due to seawater intrusion is among the most important problems in coastal farmlands. Inverse estimation of unsaturated soil hydraulic and solute transport properties represents a fundamental step to understand saltwater intrusion dynamics. A three-year study was conducted in a maize field bounding the southern Venice Lagoon. Volumetric water content θ, soil matric potential ψ, and apparent electrical conductivity (ECa) were monitored hourly by five automatic monitoring stations at four depths (0.1, 0.3, 0.5 and 0.7 m). Groundwater electrical conductivity (EC) and depth to the water table were measured in five wells. In addition, soil water and groundwater samples were collected and analyzed to determine the chemical composition. Soil hydraulic parameters for the van Genuchten-Mualen equations were determined using the inverse method in Hydrus-1D. The water flow was modelled based on the daily averages of θ at the four depths and the θ values measured in the lab at selected ψ on undisturbed soil cores extracted from the five monitoring stations. Precipitation, crop transpiration, soil evaporation and depth to the water table were used as time-variable boundary conditions. Root water uptake was estimated by using Feddes model. Finally, the major ion chemistry module of HYDRUS-1D was used to model solute transport and root water uptake reduction due to osmotic stress. The use of HYDRUS-1D to understand saltwater dynamics would enable the developing of mitigation strategies to limit its detrimental effect on farmland productivity and groundwater quality.</p>

Sensitivity and uncertainty analysis of the HYDRUS-1D model for root water uptake in saline soils

2018 ◽  
Vol 69 (2) ◽  
pp. 163 ◽  
Author(s):  
Wenzhi Zeng ◽  
Guoqing Lei ◽  
Yuanyuan Zha ◽  
Yuanhao Fang ◽  
Jingwei Wu ◽  
...  
Keyword(s):  
Salt Stress ◽  
Water Uptake ◽  
Soil Salinity ◽  
Root Water Uptake ◽  
Stress Factors ◽  
Saline Soils ◽  
Growth Stages ◽  
1D Model ◽  
Maximum Root ◽  
Hydrus 1D

A variance-based global sensitivity analysis (extended Fourier amplitude sensitivity test, EFAST) was applied to the Feddes module of the HYDRUS-1D model, and the sensitivity indices including both main and total effects of actual root water uptake (RWUa) to seven Feddes parameters were quantified at different growth stages of sunflower (Helianthus annuus L.): seedling, bud, flowering and maturity. The effects of soil salinity, climate conditions, and crop root growth on parameter sensitivity were explored by analysing three precipitation frequencies and two maximum root depths across four field locations with different soil salinity levels in China’s sunflower-growing regions. Uncertainties for RWUa were evaluated at four stages with varying Feddes parameters for different field locations, precipitation frequencies and maximum root depths. We found that the water stress factor concerning ceasing root water uptake (h4), and two salt stress factors ht and Sp, indicating the salinity threshold and the slope of the curve determining the fractional decline in root water uptake per unit increase in salinity below the threshold, respectively, were three most important Feddes parameters for RWUa estimation in HYDRUS-1D. In addition, the effects of soil salinity and precipitation frequencies were stronger than maximum root depth on the order of the parameters’ impacts on RWUa. Our study suggested that h1, h2, h3h, and h3l might be determined by an economical method (e.g. literature review) in saline soils with limited observations, but it is better to calibrate wilting point (h4) and salt stress parameters (ht and Sp) based on local measurements.

scholarly journals Estimating the Root Water Uptake of Surface-Irrigated Apples Using Water Stable Isotopes and the Hydrus-1D Model

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1624 ◽  
Author(s):  
Lijian Zheng ◽  
Juanjuan Ma ◽  
Xihuan Sun ◽  
Xianghong Guo ◽  
Qiyun Cheng ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Water Use Efficiency ◽  
Water Use ◽  
Water Uptake ◽  
Root Water Uptake ◽  
Surface Irrigation ◽  
Apple Trees ◽  
1D Model ◽  
Use Efficiency ◽  
Hydrus 1D

The future production of irrigated fruit orchards in the Loess Plateau of China is threatened by a shortage of freshwater. To improve water use efficiency under conditions where irrigation is limited, it is necessary to quantify the root water uptake (RWU) of apple trees. The RWU of apple trees was estimated under surface irrigation using water stable isotope technology and the Hydrus-1D model. Using the Romero-Saltos and IsoSource models, the stable isotopes of water in stems, different soil depths, and different precipitation were analyzed in a 5-year-old dwarfing apple orchard during two seasons 2016 and 2017. Hydrus-1D model was able to simulate the RWU of apple using the maximum coefficient of determination (0.9), providing a root mean square error of 0.019 cm3 cm−3 and a relative error of 2.25%. The results showed that the main depth of RWU ranged from 0–60 cm during the growth season, with the main contribution occurring in the 0–40 cm depth. These findings indicated that reducing the traditional surface irrigation depth will be important for improving the irrigation water use efficiency.

Simulation of vegetation-soil water feedback in nemoral forests on hydromorphic soils with Hydrus-1D

2021 ◽  
Author(s):  
Andis Kalvans
Keyword(s):  
Soil Water ◽  
Water Uptake ◽  
Feedback Loop ◽  
Water Saturation ◽  
Root Water Uptake ◽  
Climate Forcing ◽  
Soil Aeration ◽  
Hydromorphic Soils ◽  
Poor Soil ◽  
Hydrus 1D

<p>It is hypothesized that northern nemoral forests on hydromorphic soils in lowland settings can enter a feedback loop were enhanced evapotranspiration led to better soil aeration enhancing root water uptake and further increase of evapotranspiration. Opposite feedback could be possible as well – poor soil aeration due to water saturation hinders the root water uptake, resulting in overall decreased evapotranspiration and preservation of waterlogged state of the soil. The feasibility of the feedback loop is explored by a Hydrus-1D simulation using artificial climate forcing. It is suggested that wet or dry years can shift the vegetation-soil water<strong> </strong>system from wet to dry state and back. The research is supported by project No. 1.1.1.2/VIAA/3/19/524.</p>

Hydrogeochemical evidence of seawater intrusion: a case study in Venice farmland

2020 ◽  
Author(s):  
Ester Zancanaro ◽  
Pietro Teatini ◽  
Elia Scudiero ◽  
Francesco Morari
Keyword(s):  
Electrical Conductivity ◽  
Groundwater Quality ◽  
Seawater Intrusion ◽  
Water Movement ◽  
Venice Lagoon ◽  
Mitigation Strategies ◽  
Land Productivity ◽  
Ionic Concentrations ◽  
Significant Difference ◽  
Monitoring Stations

<p>Saltwater contamination seriously affects groundwater quality and land productivity of coastal farmland along the Venice lagoon, Italy. Characterizing seawater intrusion dynamics represents a fundamental step to better understand its effect on soil and groundwater quality and in turn, conceive mitigation strategies. To this end, a three-year study was conducted in an experimental field bounding the southern Venice Lagoon. Volumetric water content, soil matric potential and apparent electrical conductivity (ECa) were monitored by five automatic monitoring stations at four depths (0.1, 0.3, 0.5 and 0.7 m). Groundwater electrical conductivity (EC) and depth to the water table were measured at the five stations. In addition, soil pore water at the four depths and borehole groundwater samples were collected periodically and analyzed for chemical composition. Physical and chemical analyses of the soil profiles were also carried out. Relationships between Cl<sup>-</sup>, Na<sup>+</sup>, Mg<sup>2+, </sup>Ca<sup>2+</sup>, K<sup>+</sup>, SO<sub>4</sub><sup>2-</sup>, Br<sup>- </sup>ionic concentrations, EC and soil characteristics (e.g. texture, EC1:2, exchangeable cations) were calculated by Pearson and Spearman correlation. Kruskal Wallis test was performed to test the five monitoring stations. Moreover, specific molar ratios (Cl/Br, Br/Cl, Na/Cl and K/Cl) were calculated in order to identify the main drivers affecting salinity in the field. EC and ionic concentrations showed high variability across the monitoring stations and between the different sampling dates (e.g. groundwater EC ranged between 0.33 and 17.46 dS/m). Higher EC and ionic concentration values were observed during upward soil water movement, while values were lower during percolation events (e.g. maximum Cl<sup>-</sup> concentrations were 9227.3 mg/l and 3436.1 mg/l, respectively). An high correlation resulted between Na<sup>+</sup> and Cl<sup>-</sup> ionic concentrations and EC data in four out of the five monitoring stations (r values between 0.82 and 0.92). In addition, Kruskal Wallis test showed a significant difference between EC and chemical data sampled at the five monitoring stations and different soil depths. These results allow to conclude that soil and water salinity originated from different processes such as seawater intrusion and deep brines upcoming. Understanding salinization sources would enable the definition of a mitigation strategy able to enhance land productivity and water quality.</p>

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