WATERSHEDS AS THE BASIC ECOSYSTEM: THIS CONCEPTUAL FRAMEWORK PROVIDES A BASIS FOR A NATURAL CLASSIFICATION SYSTEM¹

Abstract

A scheme is outlined to classify watersheds as ecosystems, based on their natural attributes. Two physical factors of the environment, climate and geology, are selected as state factors. Climate is the master factor that supplies energy and water to all ecosystems; geologic structure supplies the materal from which the forces of climate carve landforms to establish ecosystems. At the next lower level, soil and vegetation interact in a succession of transactions to produce a mosaic of tesseras within each watershed. It is these interacting tesseras that moderate climate and store energy within the ecosystem that influences the embedded stream. At the bottom of the scale is the stream with its passive role and inability to interact with the higher factors of the ecosystem. Thus, we have a controlling force consisting of two elements (climate and geology), a reacting force (soil and vegetation) that responds by circular conditioning to controlling forces, and at the lowest level, the stream which responds to all factors of the living system within its watershed.(KEY TERMS: watersheds; ecosystem; classification; physioclimatic control; transactional factors.)

Caracterización geomorfológica de los ríos de Galicia mediante unidades litotopográficas

“…Con el segundo nivel de la organización jerárquica, la cuenca vertiente, se estructura el territorio hidrológicamente y/o como unidad de gestión (Chorley, 1969;Lotspecich, 1980). Su caracterización por tamaños es predictiva para la magnitud de las aportaciones e, incluso, se podría esbozar el tipo de trazado en planta de los ríos (González del Tánago y García de Jalón, 2007).…”

Structures régionales du bassin de la Loire

“…Partant du principe qu'il est plus pertinent de classifier des causes que des conséquences [4], la démarche s'appuie sur une hiérarchisation des facteurs qui contrôlent le fonctionnement des hydrosystèmes [5]. Ces facteurs dépendent en premier lieu des caractéristiques naturelles du bassin versant, et sont secondairement influencés par les activités humaines.…”

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“…No caso dos processos hidrológicos, onde interagem os ciclos biogeoquímicos, o fluxo de energia e os dinâmicos fatores bióticos, em muitos casos têm-se considerado a bacia hidrográfica como a unidade ecossistêmica para estudo e planejamento (Lotspeich, 1980), sendo utilizados diferentes indicadores tais como balanço hídrico, extensão e condição da zona ripária, taxas de infiltração e de erosão do solo, diversidade de invertebrados bentônicos e qualidade da água, para mensurar e avaliar a sustentabilidade das intervenções antropogênicas em métodos de análise multicriterial (Francisco et al, 2008).…”