A Level I River Ecoregion classification System for South Africa, Lesotho and Swaziland. Report No. N/0000/00/REQ0104. Export

@techreport{citeulike:4762154, abstract = {The rationale and fundamentals of the ecoregional typing of rivers entail the following: • Chapter 3 of the National Water Act (NWA) of South Africa (Act No. 36 of 1998) refers specifically to the protection of the ecological reserve to realise long-term sustainable development. • Chapter 14 of the NWA deals, amongst other aspects, with water resource monitoring and assessment. • To enable the realisation of the protection and monitoring of the ecological reserve, it follows that the resource must be ecologically delineated and Resource Quality Objectives specified for various ecological components within this delineation. South Africa is a geologically, geomorphologically, climatically and ecologically complex country, and this results in a diverse range of ecosystems, including rivers. River ecoregional classification or typing will allow the grouping of rivers according to similarities based on a top-down nested hierarchy. The purpose is to simplify and contextualise assessments and statements on ecological water requirements. One of the advantages of such a system is the extrapolation of information from data rich rivers to data poor rivers within the same hierarchical typing context. To realise the delineation of various river types within an ecological context it was decided to follow the ecoregional typing approach developed by Omernik (1987). This approach is presently applied by the USEPA as a framework for the formulation of reference conditions and to set resource quality specifications. • Ecoregions can be identified or typed on the basis of various levels of detail. The principle of river typing is that rivers grouped together at a particular level of the typing hierarchy will be more similar to one another than to rivers in other groups. • An ecosystems approach recognizes that ecosystem components do not function as independent systems but that they exist only in association with one another. • Ecosystems and their components display regional patterns that are reflected in spatially variable combinations of causal factors such as climate, mineral availability (soils and geology), vegetation and physiography. These factors interact, but the importance of each factor in determining the character of ecosystems varies from place to place. • Omernik's (1987) approach is based on patterns of terrestrial characteristics and on the premise that relatively homogenous areas exist and that these areas can be defined by simultaneously analysing a combination of causal and integrative factors. In this approach, ecoregions are regions of relative homogeneity in ecological characteristics or in relationships between organisms and their environments. • Ecoregional classification uses multiple characteristics at each level of a typing hierarchy. Ecological regions are, then, regions within which there is relative similarity in the mosaic of ecosystems and ecosystem components (biotic and abiotic, aquatic and terrestrial). • The delineation of ecological regions requires evaluating maps of all geographic phenomena believed to cause or reflect spatial differences in ecosystems. Where combinations of these phenomena coincide spatially, the ecosystems are likely to be similar. The process requires qualitative examination to account for the differences in generality, accuracy, and particular classifications of each map. The regions are essentially sketched (Omernik 1995; Omernik pers. comm. 1998), using expert judgement to delineate boundaries. • Ecoregional classification is a hierarchical procedure that involves the delineation of ecoregions with a progressive increase in detail at each higher level of the hierarchy, i.e. essentially the same characteristics are used at the various levels but with more detail as one moves to a higher level in the hierarchy. In addition, the characteristics that are more or less important can vary from one place to another. • It must be emphasized that although several terrestrial characteristics are used in ecoregional classification, the objective is to arrive at river ecoregions. Within this context, there may be terrestrial characteristics that are not of much use in typing river ecosystems. It follows, therefore, that the ecoregional typing process followed here relates primarily to river ecosystems and that any reference to ecoregions in the text are applicable to river ecosystems and are not meant to indicate the boundaries and characteristics of terrestrial ecoregions. Based on attributes such as physiography, climate, rainfall, geology and potential natural vegetation (Kruger 1983; Schulze 1996; Low \& Rebello 1996; van Riet et. al 1997), 31 Level I ecoregions were identified compared to the 18 Level I ecoregions previously delineated (Kleynhans \& Hill 1999). Following from the Level I delineation, the next phase of this project will delineate Level II ecoregions and will use the same typing attributes but in more detail. Level II ecoregions will provide a suitable link to stream channel characteristics. Stream classification is a separate hierarchy and includes geomorphological classification according to zones, segments and reaches (Wadeson \& Rowntree 1999). It is likely that the geomorphological segment level will provide information that can be linked to biological habitat segments (i.e. fish, invertebrate and riparian vegetation habitat segments) that can form a basis for the assessment and estimation of Ecological Reserve requirements.}, address = {Pretoria, South Africa}, author = {Kleynhans, C. J. and Thirion, C. and Moolman, J.}, citeulike-article-id = {4762154}, institution = {Resource Quality Services, Department of Water Affairs and Forestry}, keywords = {classification, climate, ecology, ecosystem-management, geographical-information-systems, geology, geomorphology, pdf}, posted-at = {2009-06-06 18:04:23}, priority = {0}, title = {{A Level I River Ecoregion classification System for South Africa, Lesotho and Swaziland. Report No. N/0000/00/REQ0104.}}, year = {2005} }

TY - RPRT ID - citeulike:4762154 L3 - citeulike-article-id:4762154 N2 - The rationale and fundamentals of the ecoregional typing of rivers entail the following: • Chapter 3 of the National Water Act (NWA) of South Africa (Act No. 36 of 1998) refers specifically to the protection of the ecological reserve to realise long-term sustainable development. • Chapter 14 of the NWA deals, amongst other aspects, with water resource monitoring and assessment. • To enable the realisation of the protection and monitoring of the ecological reserve, it follows that the resource must be ecologically delineated and Resource Quality Objectives specified for various ecological components within this delineation. South Africa is a geologically, geomorphologically, climatically and ecologically complex country, and this results in a diverse range of ecosystems, including rivers. River ecoregional classification or typing will allow the grouping of rivers according to similarities based on a top-down nested hierarchy. The purpose is to simplify and contextualise assessments and statements on ecological water requirements. One of the advantages of such a system is the extrapolation of information from data rich rivers to data poor rivers within the same hierarchical typing context. To realise the delineation of various river types within an ecological context it was decided to follow the ecoregional typing approach developed by Omernik (1987). This approach is presently applied by the USEPA as a framework for the formulation of reference conditions and to set resource quality specifications. • Ecoregions can be identified or typed on the basis of various levels of detail. The principle of river typing is that rivers grouped together at a particular level of the typing hierarchy will be more similar to one another than to rivers in other groups. • An ecosystems approach recognizes that ecosystem components do not function as independent systems but that they exist only in association with one another. • Ecosystems and their components display regional patterns that are reflected in spatially variable combinations of causal factors such as climate, mineral availability (soils and geology), vegetation and physiography. These factors interact, but the importance of each factor in determining the character of ecosystems varies from place to place. • Omernik's (1987) approach is based on patterns of terrestrial characteristics and on the premise that relatively homogenous areas exist and that these areas can be defined by simultaneously analysing a combination of causal and integrative factors. In this approach, ecoregions are regions of relative homogeneity in ecological characteristics or in relationships between organisms and their environments. • Ecoregional classification uses multiple characteristics at each level of a typing hierarchy. Ecological regions are, then, regions within which there is relative similarity in the mosaic of ecosystems and ecosystem components (biotic and abiotic, aquatic and terrestrial). • The delineation of ecological regions requires evaluating maps of all geographic phenomena believed to cause or reflect spatial differences in ecosystems. Where combinations of these phenomena coincide spatially, the ecosystems are likely to be similar. The process requires qualitative examination to account for the differences in generality, accuracy, and particular classifications of each map. The regions are essentially sketched (Omernik 1995; Omernik pers. comm. 1998), using expert judgement to delineate boundaries. • Ecoregional classification is a hierarchical procedure that involves the delineation of ecoregions with a progressive increase in detail at each higher level of the hierarchy, i.e. essentially the same characteristics are used at the various levels but with more detail as one moves to a higher level in the hierarchy. In addition, the characteristics that are more or less important can vary from one place to another. • It must be emphasized that although several terrestrial characteristics are used in ecoregional classification, the objective is to arrive at river ecoregions. Within this context, there may be terrestrial characteristics that are not of much use in typing river ecosystems. It follows, therefore, that the ecoregional typing process followed here relates primarily to river ecosystems and that any reference to ecoregions in the text are applicable to river ecosystems and are not meant to indicate the boundaries and characteristics of terrestrial ecoregions. Based on attributes such as physiography, climate, rainfall, geology and potential natural vegetation (Kruger 1983; Schulze 1996; Low & Rebello 1996; van Riet et. al 1997), 31 Level I ecoregions were identified compared to the 18 Level I ecoregions previously delineated (Kleynhans & Hill 1999). Following from the Level I delineation, the next phase of this project will delineate Level II ecoregions and will use the same typing attributes but in more detail. Level II ecoregions will provide a suitable link to stream channel characteristics. Stream classification is a separate hierarchy and includes geomorphological classification according to zones, segments and reaches (Wadeson & Rowntree 1999). It is likely that the geomorphological segment level will provide information that can be linked to biological habitat segments (i.e. fish, invertebrate and riparian vegetation habitat segments) that can form a basis for the assessment and estimation of Ecological Reserve requirements. AD - Pretoria, South Africa TI - {A Level I River Ecoregion classification System for South Africa, Lesotho and Swaziland. Report No. N/0000/00/REQ0104.} KW - classification KW - climate KW - ecology KW - ecosystem-management KW - geographical-information-systems KW - geology KW - geomorphology KW - pdf AU - Kleynhans, CJ AU - Thirion, C AU - Moolman, J PY - 2005/// ER -