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Showing 2 results for Inverse Modeling


Volume 6, Issue 3 (8-2018)
Abstract

Aims: In arid and semi-arid regions, to reduce the impact of infrequent flood, groundwater recharge and decrease flood damages, runoff should be stored through Flood Water Spreading (FWS) systems. The aim of the present study was to estimate of artificial groundwater recharge by flood water spreading system in an arid region using inverse modeling and the Soil-Conservation Service-Curve-Number (SCS-CN) method in Mosian plain.
Materials and Methods: The present study is the original research which was done in a computational manner, groundwater recharge by FWS system under arid conditions of west of Iran was estimated using mathematical and empirical methods. The annual component values of the water balance equation were estimated using the mathematical model (MODFLOW). Groundwater recharge by FWS system was estimated using the inverse modeling approach for the study area. Daily rainfall data (1994-2014) was used to estimate the daily runoff from the upland using SCS-CN method. The estimated runoff was used to estimate the groundwater recharge from FWS system. The R-squared statistic test and PMWIM? Software were used.
Findings: Estimated annual average groundwater recharge by the MODFLOW model and SCS method were 6.55 and 8.47MCM respectively (1994-2014). Comparison between mathematical and empirical models showed minor differences. A minimum of 13mm daily rainfall was required to generate 1mm of recharge from the floodwater spreading system.
Conclusion: Combination of the mathematical and empirical models can increase the accuracy of the groundwater recharge predictions. Groundwater recharge in FWS system area increase with increasing of rainfall, but after the certain value of precipitation, it is nearly constant due to ponds capacity and infiltration speed limitation.

C. Chavez, C. Fuentes, F. Brambila, A. Castañeda,
Volume 16, Issue 6 (11-2014)
Abstract

Subsurface drainage systems are used to control the depth of the water table and to reduce or prevent soil salinity. Water flow in these systems is described by the Boussinesq Equation, and the Advection-Dispersion Equation coupled with the Boussinesq Equation is used to study the solute transport. The objective of this study was to propose a finite difference solution of the Advection-Dispersion Equation using a lineal radiation condition in the drains. The equations’ parameters were estimated from a methodology based on the granulometric curve and inverse problems. The algorithm needs the water flow values, which were calculated with the Boussinesq Equation, where a fractal radiation condition and variable drainable porosity were applied. To evaluate the solution descriptive capacity, a laboratory drainage experiment was used. In the experiment, the pH, temperature, and electric conductivity of drainage water were measured to find the salt’s concentration. The salts concentration evolution was reproduced using the finite difference solution of the Advection-Dispersion Equation, and the dispersivity parameter was found by inverse modelling. The numerical solution was used to simulate the leaching of saline soil. The result showed that this solution could be used as a new tool for the design of agricultural drainage systems, enabling the optimal development of crops according to their water needs and the degree of tolerance to salinity.

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