EN ISO 12958 - GEOTEXTILES AND GEOTEXTILE-RELATED PRODUCTS - DETERMINATION OF WATER FLOW CAPACITY IN THEIR PLANE

The flow of water within the plane of a geotextile is measured under varying normal compressive stresses P (20/100/200 kPa), typical hydraulic gradients i=dh/dl (i=0,1-1) and definite contact surfaces.

Taking w as width of geotextile sample, V as the volume (m3)of water collected in a time unit t (s), the in-plane water flow capacity per unit width at defined stress/gradient (qstress / gradient) at the temperature of 20 °C is given by :
q = V/(w x t )  ( m2/sec)

Note : having a gradient i=1 the water flow capacity corresponds to the transmissivity of geotextile.