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RDM Resource Directed Measures Methodologies for RDM determination in SA Dana Grobler Blue Science Consulting cc FETWater RDM network RDM methodologies legally defensible based on sound scientific and ecological principles match administrative requirements provide estimates of the water quantity and quality required allow for rapid determinations to meet demands for NWA implementation EWR methods Building Block Methodology for the assessment of environmental flow requirements for rivers Flow stressor response DRIFT Ecostatus assessments South African Water Quality Guidelines for Aquatic Ecosystems Habitat assessment procedure and biotic integrity indices Revision is ongoing Basic assumptions There is spare water in rivers The disturbance regime is a major determinant of biodiversity distribution is at least as important as volume Physical processes determine habitat and thus the biodiversity of rivers Biodiversity drives integrity of ecosystems Reserve aims to manage physical processes Rivers are resilient Water quality and quantity The Reserve include both water quantity and quality Changes in water quantity affect water quality Balancing the interaction is a complicating factor in Reserve determinations Accounting for pollutants is also a complicating factor Generic EWR determination steps Ecological reserve determination Initiate the RDM study Determine ecoregional types, delineate resource units and select study sites Determine the reference conditions Determine the present ecological status Determine the ecological importance and sensitivity Specify EWRSs Generate the ecological Reserve Reference conditions describes the conditions before modification provides a stable baseline to which the present state can be compared provides a basis for decisions regarding the management of the resource Present Ecological Status provides information on water resource health integrity degree of difference from the reference conditions in terms of the hydrology hydraulics water quality biota geomorphology Confidence levels (rivers) Method Hydrological Duration Indication of requirements possible confidence Desktop WR90 1 day Very low Rapid Site specific 2 days Low monthly data Intermediate Daily data 12-24 weeks Low-Medium Comprehensive Daily data 12-24 months Medium - High Level of confidence required determines: ‐cost of study ‐duration of study ‐size of team Generic process (cont.) Ecological reserve determination Initiate the RDM study Determine ecoregional types, delineate resource units and select study sites Determine the reference conditions Determine the present ecological status Determine the ecological importance and sensitivity Specify EWRSs Generate the ecological Reserve Summary High impact – high confidence High importance – high confidence High utilisation – high confidence Low data – low confidence No ‘right’ answer : motivate Select study sites Study sites are: representative of the resource unit (or sections thereof) located at ecologically critical points suitable for sampling by different specialists able to provide data linking flow to habitat Functions of different flows Low flows Define the basic seasonality of rivers. Freshets Usually of most NB in the dry season, particularly to alleviate WQ problems. Large floods Large, scouring floods dictate the form of the channel. Small floods Re-set a wide spectrum of conditions in the river, triggering and synchronising activities as varied as upstream migration of fish and germination of riparian seedlings. Flow Variability of flow is essential for a healthy variability ecosystem. Different conditions are created through each day and season, which control the biota being dominated by pest species. Case study: Palmiet River downstream of Arieskraal Dam Modified flow regime (seasonal river) Natural For ecological maintenance Discharge (m3 x 106) 1. Annual flood, to reset channel and ecosystem 2. Subsurface flow in dry season to maintain pools and riparian vegetation 3. First flood of wet season for life-cycle cues 4. Maintenance of aquatic habitat to allow aquatic species to complete lifecycles 1 3 4 2 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Months Specify ecological water requirements Percentage of natural flow Pristine Severely degraded Overall condition of the aquatic system Fields of study • hydrologists • hydraulic modelers • fluvial geomorphologists • aquatic chemists • riparian and aquatic botanists • fish and invertebrate biologists • microbiologists/ herpetologists and wildlife ecologists. • sociologists/health practioners/economists Considerations in determining the Reserve: Ecological Water Requirements definition of hydraulic habitat requirements for individual key biota depths current speed width substrata use individual information to build up the picture for an entire aquatic ecosystem Activity Divide into your groups and construct a set of suitability curves for. swimming conditions in rivers for young SA boys – aged 9‐11 assess: depth, velocity and substrate 15‐20 mins Discussion 5 mins Report back 5 mins Overall discussion Use the overheads being handed out now. Identifying fish habitat 1 0.8 Depth suitability 0.6 0.4 0.2 0 0 0.3 0.5 1.8 2.2 2.6 depth (m) 1 0.8 Velocity suitability 0.6 0.4 0.2 0 0 0.1 0.4 0.5 0.9 1.1 velocity (m/s) 1 0.8 Substrate suitability 0.6 0.4 0.2 0 0 2 7 8 9 10 substrate index Estuaries, rivers, groundwater and wetland The main determinant varies between components Methodologies for various components are at different stages of development Specify ecological water requirements A range of EWRs may be specified Expressed in terms of ecological category May be at or above PES Ecological implications are specified Informs the classification of the water resource EWR SCENARIOS Category B 0 Category C -0.5 Category D Ecological condition -1 Category E -1.5 -2 -2.5 0 10 20 30 40 50 60 70 80 90 100 110 157 (nMAR) VOLUME USED FOR RIVER (incl. 1:2/5/10/20 floods) EWRs are NOT the Ecological Reserve. They comprise: • EWRs for each ecosystem of interest • a range of possible scenarios giving volume and distribution of water to meet different classes • quality and quantity requirements Before the Ecological Reserve can be determined: ‐ other users must be considered; ‐ management class must be set. WHAT IS WRCS ALL ABOUT? • Required by the National Water Act (NWA) (No. 36 of 1998) • A set of guidelines and procedures for determining different classes of water resources • The desired characteristics of the resources are represented by management classes (MCs) • The MC outlines resource attributes required by DWAF and society WHAT IS THE WRCS? (cont…) _____________________________________________________________________ • WRCS will be used (later) in a (consultative) process (the classification process) to help facilitate a balance between protection and use – i.e. to recommend a MC • The economic, social and ecological implications of a MC will need to be established and communicated to all interested and affected parties (I&APs) WHAT IS THE WRCS? (cont...) _____________________________________________________________________ • The outcome of the classification process will be the Minister or delegated authority setting the MC and resource quality objectives (RQOs) for a resource • MC sets the boundaries for the volume, distribution and quality of the Reserve and the RQOs, and thus the potential allocable portion of a water resource for off-stream use Water resource classification Class I Natural • Human activity has caused no or minimal changes to the historical natural structure and functioning of biological communities (animals and plants), hydrological characteristics or the bed, banks and channel of the resource (ecological category A); Class II Moderately used/impacted • Resources that are slightly to moderately altered from their natural condition due to the impacts of human activity and water use; • retain a high degree of ecological function and integrity (ecological category B to high C); Class III Heavily used/impacted • Resources that are significantly changed from the Natural class reference conditions due to the impacts of human activity and water use but are nevertheless ecologically sustainable; where there are pressing social and economic reasons to permit uses that will cause limited, short-term and reversible degradation of the resource, cases will be considered on their merits within the framework of long-term sustainability; Class IV Unacceptably degraded resources • Unacceptably degraded resources as a result of over-exploitation; and • MC set at one class up with the aim to rehabilitate this resource to at least one higher class. Classification Still under development DWAF internal process Public participation Preliminary Reserves are recommended until the classification is finalised Preliminary refers to the legal status, not the confidence of the determination A Natural B-C Moderately used/impacted C-D Heavily used/impacted E-F Unacceptably degraded WHY IS THERE A NEED TO CONSIDER ECONOMIC, SOCIAL AND ECOLOGICAL IMPLICATIONS OF A MC? DWAF’s motto ‘ensuring some, for all, forever, together’. Economic goal of efficiency Social goal of equity Ecological goal of sustainability Generate the Reserve Basic Human Needs Classification of resource (each resource unit) Ecological Reserve (EWR for chosen class) for each resource unit Combine Reserves for resource units Set RQOs set for the water resource in its entirety, not just the ecological Reserve Give effect to RDM Operationalisation of the Reserve Development of strategies to achieve the class, Reserve and RQOs Undertaken by CMAs Adaptive management approach Monitoring of compliance and resource quality monitoring compliance and response long‐term feedback loops to management Conclusion The concept of RDM is simple, but the application is technically exacting, calling for high levels of expertise a dynamic, holistic and often innovative approach (learning by doing) opportunities to review and update methodologies
"Methodologies for RDM determination in SA"