Perforated Horizontal Recharge Pipe Modeling with Non-Linear Regress

Abstract

Population growth and urban development have led to a widespread urbanized land cover leading to a direct increase in surface runoff and a decrease in groundwater infiltration. Various efforts have been carried out in many cities and countries using recharge wells and other structures, to increase groundwater replenishment and decreased flood discharge. This effort succeeded in increasing the groundwater level but was less successful in reducing flood discharge. This study analyzed the use of perforated pipe for groundwater recharge and runoff reduction. The research aims to formulate the infiltration rate into the soil through a perforated horizontal recharge pipe from a full-scale physical model. The research was conducted using 6 pipes of 7.5 cm-30 cm in diameter, 6 types of pipe length between 200 cm-700 cm, 6 values of pipe wall porosity (0.012; 0.016; 0.020; 0.024; 0.028; and 0.032), on texture clay soils with 4 types of soil permeability (3.49x10-6 cm/sec; 7.08x10-6 cm/sec; 8.93x10-6 cm/sec; and 1.12x10-5 cm/sec). The recharge test was carried out under the pipe flow condition (water level above the groundwater level and the pipe is underneath). Observations were used to analyze the influence of 5 variables (water pressure height, pipe diameter, pipe length, wall porosity, and soil permeability) of the perforated recharge pipe by using criteria of correlation coefficient Rsquare, RMSE (Root Mean Square Error), Cp (capability) to achieve the fittest model. The result showed that all variables affect the rate of groundwater filling. Based on a comparison of prediction recharge and observation visually, statistic parameter, and difference index the best-fitted model for perforated horizontal recharge pipe is a non-linear multiple power regression with an R-square 0.8878. This formula has also been compared with the Torricelli formula (R-square 0.5034) and the Forchheimer formula (R-square 0.7647) with more suitable results. So that research on perforated horizontal recharge pipes can be used more broadly, it is necessary to research recharge pipes on other texture of soil and research recharge pipes with the position of pipes under the groundwater level.