Geomorphology is important for understanding the basic structure of a wetland and its nature, which can affect water flow patterns and the ecology of the area. Vegetation assessment is necessary because it analyzes the state of the environment in terms of land use change or disturbance, for example, natural vegetation compared to alien species serves as an indicator of the extent of change of a particular site. Certain landscape features, such as infrastructure, can disrupt the water regime, ensuring that water can be altered or change its natural course of progression, for example commercial agriculture where runoff can carry wetland water to irrigate crops (Macfarlane et al ., 2008).
Aim and Objectives
Introduction
Two of the direct benefits of wetlands considered important for wetlands in a South African context are stream flow regulation and flood mitigation (Kotze et al., 2008). It is of particular importance in areas with predominantly paved surfaces, which are likely to be found in urban areas (Oberndorfer et al., 2007). The core of these surfaces reduces stormwater surface wrinkling which increases surface area without detachment (Ehrenfeld, 2000 and O berndorfer et al., 2007).
Defining wetlands and their functions
Linking hydrogeomorphic type to wetland ecosystem benefits
Channelized valley floor wetlands do not have a distinct channel and are similar to floodplains, although they are generally less effective than floodplain systems in improving water quality, but are associated with some degree of sediment capture and removal of nutrients and toxins by their hydrogeomorphic unit (Kotze et al state that valley floor wetlands are moderately effective at mitigating floods, but are dependent on the roughness of the wetland surface, which can affect the velocity of floodwater flow and ultimately the ability of the wetland to mitigate flooding.Removal of nitrates and toxins is generally well provided at bottom wetlands without channels as in floodplains (Kotze et al., 2008).hillslopes or slopes and are connected to a well-defined channel and improve water quality by removing nutrients and toxins while assimilating nitrates due to the diffuse subsurface flow that is characteristic for infiltrating slope wetlands (Kotze et. al., 2008).
Importance of wetland size in the provision of particular benefits
Implications associated with wetlands naturally being lost in the landscape
Factors which impact wetland functionality and ecosystem service provision
The trajectory of the change assessment shows a slight deterioration in the state of the urinary system. The inconsistency may be due to the abundance of non-native vegetation being overestimated, increasing the magnitude of the impact assessment. Summary of overall wetland health based on impact assessment and change assessment.
Size of impact score: (range of impact score/100) x intensity of impact score (from top rows) 0.0. Yes See Table 3.1 Table 3.13: Extent of the impact of the loss of organic sediment for direct indicators (A) and indirect indicators (B). Size of impact score: (range of impact score/100) x intensity of impact score (from top rows) 0.1.
Hydrological, geomorphological and vegetation components of the WET-Health tool
Tools assessing wetland functionality
Hydrology is considered a driver of wetland creation and conservation because it results from the input of water through direct precipitation, runoff from nearby areas, stream flow and groundwater discharge, soils, and the groundwater table. which allows control of oil color and texture, water quality, vegetation abundance, and microbial characteristics occurring in the wetland (Ellery et al., 2010; Williams, 1991). The ability of wetlands to clean the water that flows through them depends on hydraulic characteristics such as high shoot density, which allows a higher hydraulic gradient, and the shelter gap left behind by disturbance, which allows vegetation to be colonized by competitors (Rogers 1997 ). The Wetland Index of Habitat Integrity (Wetland-IHI) is the most similar tool to WET-Health in terms of method, as the tool requires assessments of hydrology, geomorphology, and vegetation to determine the current ecological status of a category.
Tools assessing wetland goods and services
Geographic Information Systems (GIS) and remote sensing techniques have been used and are considered to be successful for the purpose of wetland monitoring. Lowry (2006) points out that GIS databases can be useful for monitoring wetlands, however, they create a large amount of data which, although easily accessible, is likely to be out of date once a database GIS data is constantly updated. A problem related to the GIS database is that the monitoring quality is good and the land implementation is good; United States Environmental Protection Agency (1999) states that land demarcation and field verification are necessary.
Conclusion
Site description
Fieldwork Level 1 and 2 WET-Health and WET-EcoServices assessments were carried out on all three wetlands. All three wetlands, consisting of eight hydrogeomorphic (HGM) units, were assessed using level 1 and 2 WET-Health and WET-EcoServices. The R obert Armstrong wetland consists of one unit – channelized valley floor (Figure 3.3), the Le Mercy wetland consists of two units – hillside connected to channel and non-channelized valley floor (Figure 3.4) and the Lake Victoria Barn Swallow roost five units – channelized and non-channelized valley floor, slope seep associated with channel, and two isolated slope seep (Figure 3.5).
Study site
WET-Management series tools
The Level 1 assessment assigns extensiveness and intensity values to the same attributes that a Level 2 assessment would assess, but does not require as much fieldwork as the Level 2 assessment. For the Level 1 assessment it is important to to notice whether a feature is present. or not and the likelihood of the magnitude of the impact on the wetland; however, a Level 2 assessment requires more detail. Rather than assessing all non-native vegetation as one attribute, the Level 2 assessment requires that each non-native plant listed as a particular species may use more water than others (Macfarlane et al., 2008).
Qualitative measures…
Questionnaire and feedback session
Criticized by the developers of the tool itself because they may be too dependent on predictors of scenarios making it difficult to rely on and translate to a municipality that requires factual scientific evidence of the condition of their wetlands in order to manage them appropriately. The Level 2 can produce accurate results due to the level of depth of fieldwork. For example, a Level 1 will show sugarcane and the extent it covers, while a Level 2 assessment will distinguish the presence of sugarcane, the extent it covers between plant types such as shrubs or trees or a combination of the two and determine the distribution of alien woody plants in riparian areas, non-riparian areas or a combination of both, as well as whether the sugarcane uses more or less water than wattle, pine or eucalyptus.
Quantitative measures
Geomorphological health
Geomorphic health is important to consider the effects of erosion and deposition (Macfarlane et al., 2008).
Vegetation health
This impact score of 0.43 (category A) for the geomorphology analysis indicates that the health condition is good and the nature of this component is unmodified and natural, but there is some change to the geomorphology present in the form of the erosion trench that may extend into a deep gully found in HGM Unit 1. However, in HGM unit 2 a dense thicket of alien invasive species can be seen in Plate 4.5 which mostly contributes to the high impact ecological score of 9.04 (F category) which indicates the vegetation has been totally or almost totally changed and if any native species remaining they are of low magnitude. The geomorphology of the wetland is in the best health condition, scoring the lowest of a 1 three m odules a t 0.43.
WET-EcoServices tool
The overall health assessment of the Qokololo wetland includes all three modules namely; hydrology, geomorphology and ecology. The scores that have been calculated for each module are reproduced in Table 3.12 and illustrate the current health status of the wetland. Trust scores are allocated to each of the aspects described in the Level 2 assessment (Appendix 3).
Limitations experienced by the researcher when undertaking this study
This facilitated the work with eThekwini Municipality and also supported the training workshop on swamp assessment tools for M sunduzi Municipality. Pilot studies were conducted, such as organizing a workshop at M sunduzi Municipality, so that the researcher could gain experience and confidence with the tools.
Introduction
Texture of mineral soil Clay Clay Clay Clay Clay Clay Clay Clay Clay Clay Clay Clay Clay Clay Clay. Seasonal No change No change No change No change No change No change No change No change.
WET-Health assessments
WET-Health assessments: Level 1
- Robert Armstrong wetland
- Le Mercy wetland
- Lake Victoria Barn Swallow roosting site wetland
WET-Health Level 2
- Robert Armstrong wetland
- Le Mercy wetland
- Lake Victoria Barn Swallow roosting site wetland
The change in surface roughness of the wetland from its natural state to its current state has increased. The impact of the changes is detrimental to its hydrological integrity, placing it in an EPES category. The vegetation module falls into an E PES category due to the many dense areas of non-native vegetation found in the unit (Table 4.9).
A possible reason for this poor WET-Health score is the presence of non-native species and annual pastures, with only one hectare of the unit being undisturbed. There are two disturbing classes: dense non-native vegetation according to Table 4.10 in the extent of 20% and unchanged area (80%). The impact of the changes is detrimental to hydrological integrity, which is why it is classified in the C category of the PES (Table 4.16).
The Level 1 assessment indicates that the hydrology will be in an E PES category and this may be due to an overestimation of its impact. A poor WET-Health score can only be associated with a small area of the unit that is not affected by vegetation change. Disturbance caused by a drain located at the bottom of the HGM unit contributes to the increased abundance of alien vegetation.
About 50% of the hydrological integrity is lost placing it in a D PES category.
Results and Discussion: WET-EcoServices Assessments
Introduction
WET-EcoServices assessments
- WET-EcoServices assessments: Level 1
- Robert Armstrong Wetland
- Le Mercy wetland
- Lake Victoria Barn Swallow roosting site wetland
- Robert Armstrong wetland
- Le Mercy wetland
- Lake Victoria Barn Swallow roosting site wetland
Inlet found in HGM unit 3 caused by the railway line impeding surface flow
These water flow patterns show signs of major changes due to surrounding features whose impact on the wetland has already been discussed. In terms of wetland geomorphology, the degree to which sediment deposition can be related to the occurrence, distribution, size, activity, and extent of gully and ditch erosion, or even the reduction of ground vegetation in a watershed or wetland, creates sediment during rainfall events. The location of depositional features occurring in a wetland plays a role in determining potential impacts because as suggested by M acfarlane et al (2008); if they occur in a wetland, as shown in Plate 4.4, this can hinder wetland development.
A trench occurring in HGM unit 2
The impacts of these deposition features are assessed in relation to the extent to which they replace and remove pre-existing wetland features, which is indicated by plates 3.2 and 3.3, which are calculated in table 3.8.
An anthropogenic induced gully along the fenced roadside in HGM unit 3
The vegetation in the wetland based on the calculations in table 3.10 remains consistent with the field evaluation as the species has been identified mainly as dryland instead of obligate species. Among the number of species identified, there are alien invasive plants that are prominent throughout HGM units 1, 2 and 3.
Dense alien vegetation occurring in HGM unit 2
