Wetland and Aquatic

The screening of a proposed development site should ideally be conducted prior to the draft site layout being finalised. This is to ensure that all potential sensitive areas within the proposed site are identified to inform the overall site layout, and thus reduce the risk of impact and any potential delays that may otherwise be evident during the Environmental Authorisation (EA) and Water Use License Application (WULA) processes. At present, the newly required Department of Environment, Forestry, and Fisheries (DEFF) environmental screening tool report, which must be generated for every proposed development, provides an initial desktop sensitivity rating of a proposed site, including the aquatic and wetland sensitivity of the systems that may be situated within the boundary. The desktop sensitivity will be displayed as low, medium, or very high based on the SANBI environmental data input relevant to the proposed site. Every site, regardless of it being identified as having low sensitivity at a desktop level, must undergo an initial site sensitivity verification by an Environmental Assessment Practitioner (EAP), or preferably a SACNASP registered specialist with expertise in the relevant field (i.e. wetland and aquatic ecology). The outcome of the initial site sensitivity verification must be recorded in the form of a report that must, in terms of wetland and aquatic resources; 1) Confirm or dispute the current on-site sensitivity of watercourses against the DEFF screening report results, 2) Contain a motivation and evidence (e.g. photographs) of either the verified or different watercourse sensitivity and 3) Be submitted with the relevant DEFF screening report in accordance with the EIA Regulations (DEA, 2017).

The abovementioned initial site sensitivity verification essentially constitutes the wetland and aquatic screening. The screening process will involve ENVASS conducting a desktop study of the site from a freshwater resources perspective and a desktop delineation of all watercourse within the boundary. Thereafter, a once-off site visit will be undertaken by a suitably qualified, professionally registered SACNASP natural scientist to ground the truth of the watercourse delineated at a desktop level. The Department of Water Affairs and Forestry (DWAF) “A practical field procedure for identification and delineation of wetland and riparian areas” will be implemented on-site to delineate all watercourse within the proposed site. The data obtained during this process, as well as a Wetland and Aquatic Biodiversity Compliance Statement, will be presented within a formal Screening Report that will be submitted to the client for comment and subsequent finalisation if all is deemed to be in order. The screening report can be used to inform the site layout and design of a proposed development and should be submitted to the relevant DEFF and/or DWS officials to guide the EIA and WULA processes.

In instances where a proposed development is considered to be of a high or medium risk of impacting a watercourse (wetlands and rivers), a full impact assessment may be required. Other situations where a full watercourse assessment may be required would be if a baseline study is requested for a proposed site. This will essentially form the initial results against which all future studies within the wetland and aquatic field can be compared to, to determine whether positive or negative changes have occurred to the relevant watercourses. When conducting watercourse impact assessments associated with the WULA and EA processes, a 500 Metre (m) and 100 m assessment radius around all wetlands and rivers, respectively, will be adopted during the study. This constitutes the regulatory area associated with each at-risk wetland or river and will thus be used as the study area within the assessment (DWS; GN509, 2016).

The process of conducting a full watercourse impact assessment will involve the implementation of the following steps and associated methodologies and/or guidelines:

The National Water Act (Act no. 36 of 1998) defines a wetland as “land which is transitional between terrestrial and aquatic systems, where the water table is usually at, or near to the surface, or the land is periodically covered with shallow water and which land under normal circumstances supports, or would support, vegetation adapted to life in saturated soil”. In line with this definition, and the Department of Water and Sanitation General Notice (GN) 509 of 2016, the outer boundary of a wetland or pan is, therefore, the outer temporary zone (i.e. the boundary between the temporary wetness zone and terrestrial zone). This is delineated in-field through the implementation of the Department of Water Affairs and Forestry (DWAF) “A practical field procedure for identification and delineation of wetland and riparian areas” (DWAF, 2005-08). According to the South African Society, a wetland delineation includes; confirmation of the presence (and size) of a wetland and an approximate determination of the outermost boundary of a wetland. Additionally, a wetland delineated should result in; 1) a wetland boundary indicated on a map and where necessary verified in the field by means of a survey, 2) a map that clearly indicates data collection points (i.e. soil auger sites), and the boundaries of the delineated wetland using available terrain and aerial imagery information and 3) a report that explains how the boundary was determined.

Subsequent to undertaking and finalising the wetland delineation, the relevant wetland systems need to be classified into Hydrogeomorphic (HGM) Units. HGM units are wetlands, or portions of wetlands, that have very similar hydrological and geomorphological characteristics based on; 1) geomorphic setting, 2) water source and 3) hydrodynamics. This is achieved by implementing the legislated methodology by Ollis et al. (2013), titled ‘Classification system for wetland and other aquatic ecosystems in South Africa’. All of the above would be presented in a Wetland Delineation report that will be submitted to the client for comment and subsequent finalisation if all is deemed to be in order.

Biomonitoring is defined as the act of observing and assessing the state and ongoing changes in ecosystems, components of biodiversity, and landscape, including the types of natural habitats, populations, and species (Bondaruk et al., 2015). The periodic implementation of biomonitoring using the South African Scoring System Version 5 (SASS5) methodology (Dickens & Graham, 2002), within low-to-medium flow rivers and NOT wetlands, impoundments, or other lentic habitats, is considered the best rapid aquatic macroinvertebrate assessment within South Africa at present. The SASS5 methodology should not be implemented in isolation and should be supplemented by at least the assessment of aquatic habitat integrity and availability within the relevant assessment reached via implementation of the Index of Habitat Integrity (IHI) (Kleynhans, 1996; Kleynhans et al., 2008) and Integrated Habitat Assessment System (IHAS) (McMillan, 1998) tools, respectively. Additional tools such as the Fish Response Assessment Index (FRAI) (Kleynhans et al., 2007), Riparian Vegetation Response Assessment Index (VEGRAI) (Kleynhans et al., 2007), and Macroinvertebrate Response Assessment Index (MIRAI) (Thirion, 2007) should also be considered when conducting an in-depth aquatic biomonitoring study.

All of the above-mentioned methodologies and tools are frequently implemented by the ENVASS in-house specialists during routine and once-off aquatic biomonitoring studies, either applicable to Water Use License (WUL) conditions, or the baseline Environmental Impact Assessment (EIA) process. The ENVASS aquatic specialists who conduct said studies have been accredited to do so by the national Department of Water and Sanitation (DWS) and are professionally registered with SACNASP, and thus are considered to be compliant in terms of current environmental legislation.

Subsequent to a proposed development being constructed, or an activity such as a mine being established it may be evident that there will be considerable negative impact on the receiving aquatic environment that should be remediated. This is usually determined during the initial Environmental Impact Assessment (EIA) phase of a project when specialist studies and impact assessments are conducted. The outcomes of which, and subsequent to the implementation of the Department of Environmental Affairs (2013) mitigation hierarchy, may present that rehabilitation of impacts will be required. The mitigation hierarchy aims to first avoid negative impacts, but if this is not possible the next tier is to minimise these impacts. Effective minimisation can eliminate some impacts and reduce others allowing for sustainability targets to be met. The next consideration is restoration, or rehabilitation which takes place where minimisation efforts have failed to reach the required remediation target. At this stage, the exact quantity of functional aquatic habitat (hectare equivalents) that may be lost as a result of a proposed development, or activity must be calculated. This will inform the level of rehabilitation that should be considered for the project.

Based on the perceived loss of direct area (Hectares) and the calculated hectare equivalent (ha equiv.) loss of functional aquatic habitat, appropriate mitigation and rehabilitation measures must be formulated in an effort to remediate the impacts within a specific hydrogeomorphic (HGM) Unit (i.e. wetland) and improve the state of the systems back to a near-natural, or pre-development condition. HGM unit-specific rehabilitation goals, objectives, and targets are formulated to guide the required rehabilitation of each at-risk system.

To calculate the theoretical effect of the proposed rehabilitation measures on the integrity of the at-risk HGM unit, the ENVASS specialist will determine the pre- and post-development Present Ecological State (PES) scores, otherwise referred to as the integrity, of the aquatic habitat using legislated and best-practice methodologies and tools. In terms of wetland rehabilitation, this would be the WET-Health tool (MacFarlane et al., 2009), which uses three modules, namely; hydrology, geomorphology, and vegetation, to calculate the PES score of a specific HGM unit. The pre-and post-development PES scores are then converted into a ha equiv. score, which is essentially a representation of the integrity of an HGM unit expressed as an area, to compare the pre and post-development scenarios.
If the difference between the pre-and post-development has equiv. scores are positive, it indicates that the theoretic rehabilitation measures proposed have the potential to remediate the perceived impacts of the proposed development, or activity on the receiving aquatic environment, and thus ensure a ‘no net loss of biodiversity’ in the post-development scenario. However, if the difference is recorded to be negative there will be a residual impact on the receiving aquatic environment, and further steps within the DEA mitigation hierarchy must be applied.

The ENVASS in-house specialists have conducted numerous conceptual rehabilitation and monitoring programs for various proposed development and activities and would be well-suited to assist with any rehabilitation needs your organisation may require.
FRAI (Fish Response Assessment Index)

The purpose of the Fish Response Assessment (FRAI) is to provide a habitat-based, cause-and-effect underpinning fish communities and habitats to interpret the deviation of the fish assemblage from a Fish Reference Frequency of Occurrence (FROC) database in accordance with the SQR fish data from DWS (2013) and is implemented by the National River Health Programme (Kleynhans et al., 2007). The FRAI methodology was implemented to evaluate the existing state of the fish communities. This community metric measure allows for the evaluation of a range of metrics (flows, cover feature availability, migration impacts, water quality impacts, and alien invasive fish’s impacts) that are known to affect fish community conditions (Kleynhans et al., 2007).

Effective fish sampling included an electro-fishing apparatus (SAMUS 1000®) for 45 minutes per site. Stunned fish is then collected, photographed, identified, and released. All fish sampled were identified using Skelton (2001). Fish data was collected using the protocol prescribed for velocity/depth-categorised habitats (Kleynhans et al., 2007). Undercut banks and riparian vegetation were identified, and their coverage was estimated and scored. The fish and environmental data collected during this study were used to determine the ecological integrity of the fish communities. The reference frequency of occurrence developed by Kleynhans et al. (2007) was used in conjunction with the fish species list per quaternary reach in the SQR data provided by DWS to determine the reference fish species list in order to calculate the FRAI.

The FRAI was used to address specific information requirements regarding the response of fish assemblages to changes in the environment (Kleynhans et al, 2007). These ecosystem variables usually include physical and chemical variables, which are referred to as “ecological driver components”.

An assessment of the responses of the species metrics to changing environmental conditions may be done either through direct measurement (surveys) or concluded from the change in environmental conditions (habitat) (Kleynhans et al., 2007). Evaluation of the derived response of species metrics to habitat changes is based on knowledge of the ecological requirements of species. Changes in environmental conditions are related to fish stress and form the basis of ecological response interpretation (Kleynhans et al., 2007). These metric groups include the available habitats or velocity and depth; a cover metric that considers the preferences of overhanging vegetation, aquatic vegetation, water column, substrata as well as undercut banks and root wads; flow modifications in terms of volume, timing, and the duration of flows; migration and introduced species. As a result, expected and actual patterns can be evaluated to achieve an Ecological Category (EC) rating as seen in the table below.
Category A: Unmodified, natural | Score 90-100

Category B: Largely natural with few modifications. A small change in natural habitats and biota may have taken place but the ecosystem functions are essentially unchanged. | Score 80-90

Category C: Moderately modified. A loss and change of natural habitat and biota have occurred but the basic ecosystem functions are still predominantly unchanged. | Score 60-79

Category D: Largely modified. A large loss of natural habitat, biota, and basic ecosystem functions has occurred. | Score 40-59

Category E: The loss of natural habitat, biota, and basic ecosystem functions is extensive. | Score 20-39

Category F: Modifications have reached a critical level and the lotic system has been modified completely with an almost complete loss of natural habitat and biota. In the worst instances, the basic ecosystem functions have been destroyed and the changes are irreversible. | Score 0

Riparian vegetation areas are divided into two sub-zones, marginal and non-marginal zones. This is important given that riparian vegetation distribution and species composition vary in different sub-zones, which has implications for flow-related impacts. The EC of the riparian zone is then assessed using the Riparian Vegetation Response Assessment Index (VEGRAI) level 3 (Kleynhans et al., 2007).

Since all VEGRAI assessments are relative to the natural unmodified conditions (reference state) it is necessary and important to define and describe the reference state for the study area. This is done (in part) before going into the field, using historic aerial imagery, present and historic species distributions, general vegetation descriptions of the study area, any anecdotal data available and knowledge of the area, and comparison of the study area characteristics to other comparable sections of the stream that might be in a better state. With this information, the reference (and present state) is quantified on site; the assessor reconstructs and quantifies the reference state from the present state by understanding how visible impacts have caused the vegetation to change and respond. Impacts on riparian vegetation at the site are then described and rated. It is important to distinguish between a visible/known impact (such as flow manipulation) and the response of riparian vegetation to other impacts such as erosion and sedimentation, alien invasive species, and pollution. If there is no response to riparian vegetation, the impact is noted but not rated since it has no visible/known effect. These impacts are then rated according to a scale from 0 (No Impact) to 5 (Critical Impact). Once the riparian zone and sub-zones have been delineated, the reference and present states have been described and quantified (basal cover is used), and species description for the study area has been compiled, the VEGRAI metrics are rated and qualified (Kleynhans et al., 2007).

The riparian ecological integrity was assessed using the spreadsheet tool that is composed of a series of metrics and metric groups, each of which is rated in the field with the guidance of data collection sheets. The metrics in VEGRAI describe the following attributes associated with both the woody and non-woody components of the lower and upper zones of the riparian zone:

Results from the lower and upper zones of the riparian vegetation are then combined and weighted with a value that reflects the perceived importance of that particular criterion in determining habitat integrity, allowing this to be numerically expressed in relation to the perceived benchmark. The score is then placed into one of six classes, namely A to F (Kleynhans et al., 2007).