A GEOGRAPHIC INFORMATION SYSTEM PROCEDURE TO QUANTIFY DRAINAGE‐BASIN CHARACTERISTICS¹

Abstract

The Basin Characteristics System (BCS) has been developed to quantify characteristics of a drainage basin. The first of four main BCS processing steps creates four geographic information system (GIS) digital maps representing the drainage divide, the drainage network, elevation contours, and the basin length. The drainage divide and basin length are manually digitized from 1:250,000‐scale topographic maps. The drainage network is extracted using GIS software from 1:100,000‐scale digital line graph data. The elevation contours are generated using GIS software from 1:250,000‐scale digital elevation model data. The second and third steps use software developed to assign attributes to specific features in three of the four digital maps and analyze the four maps to quantify 24 morphometric basin characteristics. The fourth step quantifies two climatic characteristics from digitized State maps of precipitation data. Compared to manual methods of measurement, the BCS provides a reduction in the time required to quantify the 26 basin characteristics. Comparison tests indicate the BCS measurements are not significantly different from manual topographic‐map measurements for 11 of 12 primary drainage‐basin characteristics. Tests indicate the BCS significantly underestimates basin slope. Comparison‐measurement differences for basin slope, main channel slope, and basin relief appear to be due to limitations in the digital elevation model data.

Uso do geoprocessamento na identificação de conflito de uso da terra em áreas de preservação permanente na bacia hidrográfica do rio Alegre, Espírito Santo.

“…A abordagem com base em produtos derivados a partindo desses algoritmos tem substituído, com vantagens, os métodos manuais tradicionalmente utilizados , permitido a obtenção de resultados menos subjetivos, em menor tempo e replicáveis (Tribe, 1992) e apresentado níveis de exatidão comparáveis aos obtidos por métodos manuais (Garbrecht e Martz, 1993;Eash, 1994). A funcionalidade e eficácia desses procedimentos, integrada às informações produzidas pelas imagens de satélite, sobretudo, as de alta resolução espacial, podem produzir diagnósticos e fornecer subsídios capazes de identificar e mensurar a ocorrência de conflito de uso da terra em áreas de preservação permanente, fortalecendo as ações ambientais de monitoramento e como suporte para os instrumentos jurídicos de controle e fiscalização desses ambientes.…”

Improving hydrological information acquisition from DEM processing in floodplains

“…These models involve the definition of the internal drainage structure described by flow direction from cell to cell, the river network segments and the related sub-watersheds. Over recent decades several automated or semi-automated methods have been developed to retrieve data from digital elevation models (DEMs) (O'Callaghan and Mark, 1984;Band, 1986;Jenson and Domingue, 1988;Tribe, 1992;Eash, 1994). However, despite the improvements provided by the proposed methods, a realistic drainage structure cannot always be achieved.…”

Utilising published data for DTM construction and drainage basin delineation in the Modder River catchment, Free State, South Africa

“…Deng et al (2008) describe the purpose of digital terrain analyses by, amongst other things, examining or defining the relationships between the terrain and biophysical processes. Research done on small-scale source data (1:250,000) in the USA indicates a time saving and foresees the possibility that the accuracy of the technique can be improved using a larger scale (Eash 1994). Nogami (1995) defines several morphological parameters in terms of the DTM, usually with reference to pour points (a stream outlet) and upstream attributes.…”