Data/hora: 22/06/2024 11:06:02

Biblioteca(s): | Embrapa Meio Norte / UEP-Parnaíba.
Data corrente: | 01/09/1993
Data da última atualização: | 01/09/1993
Autoria: | LUTHIN, J. N.; TAYLOR, G. S.; PRIETO, C.
Título: | Exit gradients into subsurface drains.
Ano de publicação: | 1968
Fonte/Imprenta: | Hilgardia, v.39, n.15, 1968.
Idioma: | Inglês
Conteúdo: | Exit gradients were investigated for flow into circular drain pipes ofvarious outer diameters. Kirkham's equation for the distribution of hydraulic head and the stream function around buried drain pipes in soilunder ponped conditions was programmed for the digital computer and solutions were obtained for a number  of situations of interest. The program simultaneously gives the hydraulic head function, the stream fucntion, and  the flow rate into the drain. From these flow nets the exitgradients were calculated as a function of drain depths, drain outer diameter, and depths to the impermeable barrier. In all cases the drainspacing was taken constant as 50 feet. A comparison was made with on case of a gravel envelope 6 inces high and 24 inches wide. The results of the analysis indicate that exit gradients in excess of critical gradients for fine sand are encounterered in almost every case. The exit gradient increases as the drain diameter decreases. Depths to the impermeable barrier is a factor in that the exit gradient derecreases as the impermeable barrier approaches the bottom of the drain pipe. The use of a gravel envelope substantially decreases the exit gradient. The effectof perforation spacing was  not investigated. The drains are considered to be completely permeable.
Palavras-Chave: | Drenos subterraneos; Gradiente hidraulico; Subterranean drain.
Thesagro: | Água; Drenagem; Solo.
Thesaurus Nal: | drainage; soil; water.
Categoria do assunto: | --
Registro original: | Embrapa Meio Norte / UEP-Parnaíba (CPAMN-UEPP)
Exemplares: | CPAMN-UEPP - (2699-1) - ADD - SP - -- -  -  - 1993.04969 - DIS