scholarly journals Simulations of freshwater lens recharge and salt/freshwater interfaces using the HYDRUS and SWI2 packages for MODFLOW

2018 ◽  
Vol 66 (2) ◽  
pp. 246-256 ◽  
Author(s):  
Adam Szymkiewicz ◽  
Anna Gumuła-Kawęcka ◽  
Jirka Šimůnek ◽  
Bertrand Leterme ◽  
Sahila Beegum ◽  
...  
Keyword(s):  
Coastal Aquifers ◽  
Saltwater Intrusion ◽  
Potential Evapotranspiration ◽  
Capillary Rise ◽  
Richards Equation ◽  
Weather Data ◽  
Freshwater Lens ◽  
Variable Density Flow ◽  
Soil Hydraulic ◽  
Recharge Rates

AbstractThe paper presents an evaluation of the combined use of the HYDRUS and SWI2 packages for MODFLOW as a potential tool for modeling recharge in coastal aquifers subject to saltwater intrusion. The HYDRUS package for MODFLOW solves numerically the one-dimensional form of the Richards equation describing water flow in variablysaturated media. The code computes groundwater recharge to or capillary rise from the groundwater table while considering weather, vegetation, and soil hydraulic property data. The SWI2 package represents in a simplified way variable-density flow associated with saltwater intrusion in coastal aquifers. Combining these two packages within the MODFLOW framework provides a more accurate description of vadose zone processes in subsurface systems with shallow aquifers, which strongly depend upon infiltration. The two packages were applied to a two-dimensional problem of recharge of a freshwater lens in a sandy peninsula, which is a typical geomorphologic form along the Baltic and the North Sea coasts, among other places. Results highlighted the sensitivity of calculated recharge rates to the temporal resolution of weather data. Using daily values of precipitation and potential evapotranspiration produced average recharge rates more than 20% larger than those obtained with weekly or monthly averaged weather data, leading to different trends in the evolution of freshwater-saltwater interfaces. Root water uptake significantly influenced both the recharge rate and the position of the freshwater-saltwater interface. The results were less sensitive to changes in soil hydraulic parameters, which in our study were found to affect average yearly recharge rates by up to 13%.

scholarly journals Direct measurement of the soil water retention curve using X-ray absorption

2004 ◽  
Vol 8 (1) ◽  
pp. 2-7 ◽  
Author(s):  
A. Bayer ◽  
H.-J. Vogel ◽  
K. Roth
Keyword(s):  
Soil Water ◽  
Hydraulic Properties ◽  
Capillary Rise ◽  
Water Dynamics ◽  
Richards Equation ◽  
Water Retention Curve ◽  
Soil Hydraulic Properties ◽  
X Ray ◽  
Soil Hydraulic ◽  
X Ray Absorption

Abstract. X-ray absorption measurements have been explored as a fast experimental approach to determine soil hydraulic properties and to study rapid dynamic processes. As examples, the pressure-saturation relation θ(Ψ) for a uniform sand column has been considered as has capillary rise in an initially dry sintered glass column. The θ(Ψ)-relation is in reasonable agreement with that obtained by inverting a traditional multi-step outflow experiment. Monitoring the initial phase of capillary rise reveals behaviour that deviates qualitatively from the single-phase, local-equilibrium regime described by Richards’ equation. Keywords: X-ray absorption, soil hydraulic properties, soil water dynamics, Richards’ equation

Assessment of Saltwater Intrusion Vulnerability in the Coastal Aquifers in Ninh Thuan, Vietnam

2021 ◽  
pp. 703-712
Author(s):  
Quy Nhan Pham ◽  
Thi Thoang Ta ◽  
Thanh Le Tran ◽  
Thi Thu Pham ◽  
The Chuyen Nguyen
Keyword(s):  
Coastal Aquifers ◽  
Saltwater Intrusion

A note on saltwater intrusion in coastal aquifers

1990 ◽  
Vol 4 (2) ◽  
pp. 123-134 ◽  
Author(s):  
M. Sherif Mohsen ◽  
Vijay P. Singh ◽  
Abdelwahab M. Amer
Keyword(s):  
Coastal Aquifers ◽  
Saltwater Intrusion

Estimating water fluxes in Douglas-fir plantations

1985 ◽  
Vol 15 (4) ◽  
pp. 701-707 ◽  
Author(s):  
Susan J. Riha ◽  
Gaylon S. Campbell
Keyword(s):  
Soil Water ◽  
Root Zone ◽  
Potential Evapotranspiration ◽  
Field Measurements ◽  
Douglas Fir ◽  
Root Uptake ◽  
Richards Equation ◽  
Water Fluxes ◽  
Air Temperatures ◽  
Dimensional Finite Element

A model was developed to estimate water fluxes in Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) plantations using daily measurements of precipitation and maximum and minimum air temperatures. Soil water flow was modeled using a one-dimensional finite element solution to the Richards equation, with precipitation and root uptake of water included as source and sink terms. Soil hydraulic properties varied as a function of depth. Root uptake of water was based on an analog water uptake model modified to include root resistance and cylindrical flow of water. Potential evapotranspiration was calculated assuming leaf and air temperature did not differ and assuming stomatal conductance was dependent on the vapor density deficit of the air. Model validity was tested by comparing predictions with field measurements of soil water content made in the summer of 1978 at two locations in western Washington. In general, the model predicted the observed drying of the soil. Aspects of the simulated water budget for these Douglas-fir stands considered most significant were (i) the use of soil-stored water for transpiration in the summer, (ii) the net flux of water into the root zone from deeper in the soil during the summer, (iii) the dependence of water reaching the soil in the summer on the intensity of rainfall, (iv) the large percentage of the total transpiration that occurred in spring and fall, and (v) the large amount of water moving out of the soil profile in the winter.

scholarly journals The study of potential evapotranspiration in future periods due to climate change in west of Iran

2018 ◽  
Vol 10 (1) ◽  
pp. 161-177 ◽  
Author(s):  
Ahmad Rajabi ◽  
Zahra Babakhani
Keyword(s):  
Climate Change ◽  
Potential Evapotranspiration ◽  
Circulation Model ◽  
Weather Data ◽  
Maximum Temperature ◽  
Global Circulation Model ◽  
Content Type ◽  
Global Circulation ◽  
Change Effect ◽  
Climate Change Effect

Purpose This study aims to present the climate change effect on potential evapotranspiration (ETP) in future periods. Design/methodology/approach Daily minimum and maximum temperature, solar radiation and precipitation weather parameters have been downscaled by global circulation model (GCM) and Lars-WG outputs. Weather data have been estimated according to the Had-CM3 GCM and by A1B, A2 and B1 scenarios in three periods: 2011-2030, 2045-2046 and 2080-2099. To select the more suitable method for ETP estimation, the Hargreaves-Samani (H-S) method and the Priestly–Taylor (P-T) method have been compared with the Penman-Monteith (P-M) method. Regarding the fact that the H-S method has been in better accordance with the P-M method, ETP in future periods has been estimated by this method for different scenarios. Findings In all five stations, in all three scenarios and in all three periods, ETP will increase. The highest ETP increase will occur in the A1B scenario and then in the A1 scenario. The lowest increase will occur in the B1 scenario. In the 2020 decade, the highest ETP increase in three scenarios will occur in Khorramabad and then Hamedan. Kermanshah, Sanandaj and Ilam stations come at third to fifth place, respectively, with a close increase in amount. In the 2050 decade, ETP increase percentages in all scenarios are close to each other in all the five stations. In the 2080 decade, ETP increase percentages in all scenarios will be close to each other in four stations, namely, Kermanshah, Sanandaj, Khorramabad and Hamedan, and Ilam station will have a higher increase compared with the other four stations. Originality/value Meanwhile, the highest ETP increase will occur in hot months of the year, which are significant with regard to irrigation and water resources.

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