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Methodologies for RDM determination in SA

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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

				
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posted:2/10/2011
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