The initiation of natural drainage networks

Abstract

The initiation of drainage networks in the natural landscape has been a fundamental focal point for geomorphology since the dawn of modern scientific investigation, when Hutton (1975) and Playfair (1802) proposed that rivers occupy the valleys which they have created. Drainage networks are fundamental because water is the prime active ingredient in erosion and transportation processes in most landscapes, including many in regions normally deficient in water. Drainage processes exert essential controls on hillslope development as well as on channel development, not simply in the classical Davisian sense that landslope profiles are controlled by the rate of removal of material from the base of the slope. Drainage processes also form an integral part of the ensemble of processes acting within the hillslope domain. Despite the fact that in most geomorphological textbooks 'drainage networks' are still synonymous with 'channel networks', networks of drainage routes occur in a wide spectrum of scales from river channels to soil pores and many of the smaller scale networks may have equal or greater control over the evolution of hillslope form. I Interaction between different scales of network and initiating processesFour core types of network can be identified within this spectrum of drainage routes, although many intermediate and combined forms exist. These may be grouped as: 1) hollows, seepage lines and percolines; 2) macropores, pseudopipes and pipes; 3) groundwater drainage networks; and 4) rills, gullies and channels (Jones, 1971).Whilst all categories possess the most basic property of a network, which is linear concentration of flow, all Group 1 forms and a few Group 2 forms lack a definite linear void or open channel. Most attention has been directed to Group 4 forms, i.e. to open channels, but forms in groups 1 and 2 are currently receiving increased recognition and attention. Gregory (1979) noted that the drainage network consists of an 'amalgam of several types of link' and that classification of the elements within the network is important for modelling processes, interpreting recent changes and predicting future developments. Newson and Harrison (1978) produced a map of these links as a basis for channel studies in the Institute of Hydrology's Plynlimon catchments.

How do disconnected macropores in sloping soils facilitate preferential flow?

“…Our findings related to subsurface erosion processes and associated soil piping are relevant because they relate to the evolution of preferential subsurface pathways, and possibly the development of streambank instability and surface erosion features such as gullies (Jones, 1987). Mechanisms of subsurface erosion have been described by Dunne (1990), and detailed field investigations of these erosion and sediment transport processes have been conducted in various settings (Hagerty, 1991b;Terajima et al, 1997;Sayer et al, 2006).…”

A non‐conventional watershed partitioning method for semi‐distributed hydrological modelling: the package ALADHYN

“…Also, the scale of topographic maps usually affects channel head locations depicted through blue lines. Furthermore, it is quite difficult to give an objective definition of channel heads, as the drainage network depends on different factors such as the discharge or the rain intensity (Day, 1978;Jones, 1987).…”

Rola erozji źródliskowej w inicjacji i rozwoju sieci drenażu = The role of seepage erosion in the initiation and development of drainage system

“…Zlewnie źródliskowe stanowią ważne obszary denudacji oraz dostawy wody i materiału do położonych niżej części systemu fl uwialnego, gdzie następuje przejście od rozproszonych przestrzennie procesów stokowych do działających skoncentrowanie procesów fl uwialnych (Kirkby i Chorley, 1967;Dunne, 1980;Jones, 1987). Dotychczas jednak niewielka część polskich badań sieci dolinno--rzecznej prowadzona jest w górnych odcinkach rzek, a w efekcie charakterystyka początku dolin rzecznych pod kątem procesów geomorfologicznych odpowiedzialnych za ich powstanie i ewolucję pozostaje niepełna.…”

“…Przejawy morfologicznego oddziaływania wypływów wód podziemnych obserwowane są na terenach lądowych o zróżnicowanej budowie geologicznej (por. Laity, 1980;Laity i Malin, 1985;Dunne, 1980Dunne, , 1990Schumm i Phillips, 1986;Jones, 1987;Howard i Kochel, 1988;Baker, 1990;Onda, 1994;Uchupi i Oldale, 1994;Schumm i inni, 1995;Nash, 1996;LaFleur, 1999;Spence i Sauchyn, 1999;Mastronuzzi i Sanso, 2002;Lamb i inni, 2006), a także w wybranych podmorskich kanionach na stoku kontynentalnym (Paull i inni, 1990;Orange i inni, 1994). Erozji źródliskowej przypisywano również powstanie form dolinnych poza Ziemią, na Marsie i Tytanie (Higgins, 1982;Tanaka i inni, 1998;Malin i Carr, 1999;Malin i Edgett, 2000;Gulick, 2001;Aharonson i inni, 2002;Stepinski i Coradetti, 2004;Marra i inni, 2015), co jest obecnie krytycznie weryfi kowane (Lamb i inni, 2006(Lamb i inni, , 2008.…”