Groundwater Reserve, Ecological Reserve, National Water Act, water resource protection, water resource classification, RQOs

Transcription

1 Groundwater Reserve a critical review Umvoto Africa (Pty) Ltd, P.O. Box 61, Muizenberg 7950, South Africa Kornelius@umvoto.com, (work), (fax) Abstract The concept of the Groundwater Reserve is enshrined in the National Water Act that stipulates that a classification of all significant water resources must be undertaken and the Reserve requirements be determined and gazetted. The Reserve covers two different aspects, the Ecological Reserve to protect the water dependent ecosystems and the Basic Human Needs (BHN) Reserve to ensure that all people who depend on that water resource have sufficient water for their livelihood. The approach for determining and implementing the Reserve that was developed for surface water resources was adopted for groundwater resources as provided for in the GRDM Manual, inter alia. However, there is no separate Groundwater Reserve, but rather a groundwater component of or contribution to the ecological Reserve and BHN. Hence, the implementation of this methodology often results in undesirable outcomes and is one of the inhibiting factors for sustainable groundwater development, as some of the aspects and methods are not applicable to groundwater and not appropriate for implementation. The current separation of the Groundwater Reserve determination process from the ecological Reserve determination emphasizes this pitfall of the process and methodology. This paper provides a critical review of the current concept of the Groundwater Reserve and its implementation based on several case studies. It concludes with recommended changes to the standard methodology and a possible way forward for developing an appropriate methodology for addressing and protecting the groundwater contribution to both the ecological and BHN Reserve. Keywords Groundwater Reserve, Ecological Reserve, National Water Act, water resource protection, water resource classification, RQOs

2 1 Legal Requirements The National Water Act (NWA) outlines the legal requirements for the use and protection of the South African water resources, which includes a watercourse, surface water, estuary, or aquifer. There is no separation of different water resources throughout the NWA. The relevant chapters for this discussion are Chapter 3 Protection of water resources, and Chapter 4 Use of water. These are discussed below in relation to the concept of the Groundwater Reserve. 1.1 Classification Part 1 (of Chapter 3) provides for the first stage in the protection process, which is the development by the Minister of a system to classify the nation's water resources. The system provides guidelines and procedures for determining different classes of water resources. Section 12 Prescription of classification system (2) The system for classifying water resources may-- a) establish guidelines and procedures for determining different classes of water resources; b) in respect of each class of water resource-- i) establish procedures for determining the Reserve; ii) establish procedures which are designed to satisfy the water quality requirements of water users as far as is reasonably possible, without significantly altering the natural water quality characteristics of the resource; iii) set out water uses for instream or land-based activities which activities must be regulated or prohibited in order to protect the water resource; and c) provide for such other matters relating to the protection, use, development, conservation, management and control of water resources, as the Minister considers necessary. This procedure has been established and contains a 7-step process (DWA, 2010). There are three management classes; minimally used, moderately used and heavily used; which are defined by the allowed ecological condition (called category) of freshwater ecosystems or water resources within the defined area (see Table 1). Hence, the management class is determined for an area called Integrated Unit of Analysis (IUA), which usually comprises several quaternary catchments and a range of water resources. The recommended categories are then determined for water resources or parts thereof within the IUA boundary (called nodes or resource units), often based on a desired improvement of the present ecological status. Groundwater is not considered separately in the gazetted procedure and does not feature in the guidelines for water resource classification (DWA, 2010). However, some approaches in the guidelines that were developed for surface water and fresh water ecosystems, are not applicable for groundwater.

3 Table 1 Requirements for ecological condition for the Management Classes (Dollar et al. 2006) Management Class Class I: Minimally used Class II: Moderately used Class III: Heavily used Description The configuration of water resources within an IUA results in an overall water resource condition that is minimally altered from its pre-development condition. The configuration of water resources within an IUA results in an overall water resource condition that is moderately altered from its pre-development condition. The configuration of water resources within an IUA results in an overall water resource condition that is significantly altered from its pre-development condition. Configuration guidelines At least 60% of the freshwater ecosystems in a sub-basin are in an A or B category. At least 40% of the freshwater ecosystems in a sub-basin are in an A or B category. No requirement for A or B categories The aquifer classification system developed by Parsons (1995) and mapped by Conrad et al. (1999), based on relevance for water supply, does not match the emphasis on protection as stipulated in the guidelines, and hence cannot be applied without changing the classification system. The current Framework for Groundwater Classification and Protection (DWA, 2013) attempts to include groundwater into the water resource classification process, but falls short of achieving an integration, as the discrepancies between the different regulations for water resource protection; i.e. classification, Reserve, RQOs, water use authorisation; could not be resolved. 1.2 Resource Quality Objectives Under Part 2 of Chapter 3, the Minister is required to use the classification system established in Part 1 to determine the class and resource quality objectives of all or part of water resources considered to be significant. The purpose of the resource quality objectives is to establish clear goals relating to the quality of the relevant water resources. In determining resource quality objectives a balance must be sought between the need to protect and sustain water resources on the one hand, and the need to develop and use them on the other. The Guideline for the Determination of RQOs (DWA, 2011) describes a 7-step process, some of which are similar to the steps of the classification process. However, the guideline provides for different sub-steps to be followed for groundwater RQOs, which hinders the integration and promotes separation between groundwater and surface water. RQO are both descriptive statements and attendant numerical values for a range of indicators throughout the IUA (DWA 2011). The RQOs themselves are narrative and qualitative statements that describe the overall objectives for the resource unit (DWA 2011). They should be meaningful to stakeholders and responsible managers, and give direction for whatever action is necessary to achieve the vision for the resource. These RQOs are gazetted and are thus supported by law (DWA 2011).

4 The numerical limits give a quantitative measure of the RQOs that can be used for monitoring, such as an upper limit for slat concentrations or a lower population size limit for fish. Typically there is a paucity of scientific information on which to base such numerical limits, and so these numerical limits are not gazetted and thus may be more easily adjusted if found to be inaccurate. Section 13 Determination of class of water resources and resource quality objectives (1) As soon as reasonably practicable after the Minister has prescribed a system for classifying water resources the Minister must, subject to subsection (4), by notice in the Gazette, determine for all or part of every significant water resource-- a) a class in accordance with the prescribed classification system; and b) resource quality objectives based on the class determined in terms of paragraph (a). (3) The objectives determined in terms of subsection (1) may relate toa) the Reserve; b) the instream flow; c) the water level; d) the presence and concentration of particular substances in the water; e) the characteristics and quality of the water resource and the instream and riparian habitat; f) the characteristics and distribution of aquatic biota; g) the regulation or prohibition of instream or land-based activities which may affect the quantity of water in or quality of the water resource; and h) any other characteristic, of the water resource in question. 1.3 Reserve Determination Part 3 deals with the Reserve, which consists of two parts -- the basic human needs (BHN) Reserve and the ecological Reserve. The BHN Reserve provides for the essential needs of individuals served by the water resource in question and includes water for drinking, for food preparation and for personal hygiene. The ecological Reserve relates to the water required to protect the aquatic ecosystems of the water resource. The Reserve refers to both the quantity and quality of the water in the resource, and will vary depending on the class of the resource. Unless underground aquatic ecosystems within the aquifer are considered, there is no separate Groundwater Reserve, but rather a possible groundwater component of or contribution to the ecological Reserve and BHN Reserve. Hence, the groundwater component should be determined as part of the ecological Reserve determination and not as separate process, as currently happening.

5 1.4 Licensing The licensing of water use requires that a preliminary Reserve determination was undertaken (see Section 17 (1b)) and or the class and RQOs are determined (see Section 27 (1g)). This contradicts the statement under Chapter 3 that the class and resource quality objectives [are determined for] all or part of water resources considered to be significant. In recent licences, licence conditions cater for the uncertainty in establishing impacts of abstraction upfront. Hence, the need for classification and the determination of the Reserve prior to issuing a licence is questionable, at the least. Section 17 Preliminary Reserve (1) Until a system for classifying water resources has been prescribed or a class of a water resource has been determined, the Ministera) may, for all or part of a water resource; and b) must, before authorising the use of water under section 22(5), make a preliminary determination of the Reserve. Section 27 Considerations for issue of general authorisations and licences (1) In issuing a general authorisation or licence a responsible authority must take into account all relevant factors, including-- a) existing lawful water uses; b) the need to redress the results of past racial and gender discrimination; c) efficient and beneficial use of water in the public interest; d) the socio-economic impact-- i) of the water use or uses if authorised; or ii) of the failure to authorise the water use or uses; e) any catchment management strategy applicable to the relevant water resource; f) the likely effect of the water use to be authorised on the water resource and on other water users; g) the class and the resource quality objectives of the water resource; h) investments already made and to be made by the water user in respect of the water use in question; i) the strategic importance of the water use to be authorised; j) the quality of water in the water resource which may be required for the Reserve and for meeting international obligations; and k) the probable duration of any undertaking for which a water use is to be authorised.

6 2 Current Implementation Currently, groundwater Reserve studies are undertaken mostly in isolation and often without an ecological Reserve being determined prior or in parallel. The reasons for this are: The need for a Reserve determination for licence applications; The need to assess the allocable amount of groundwater at the same time; The limits of procurement processes within DWA; The split of responsibilities into different sub-directorates; The lack of scientific knowledge and understanding wrt surface water groundwater interaction; The lack of capacity for IWRM within the relevant authorities. Hence, most studies follow the concept of the Groundwater Reserve and its implementation as outlined in the Groundwater Resource Directed Measures (GRDM) Manual (Dennis et al., 2011). 2.1 Reserve determination The standard approach to Groundwater Reserve determinations aims to determine the allocable amount of groundwater within the study area and is based on the following equation: GW allocable = Re GW use GW Reserve (1) where Re = Recharge, GW use = current groundwater use, GW Reserve = groundwater contribution to the Reserve. Due to lack of other data at appropriate scale, the Groundwater Reserve is often equated to the natural baseflow or groundwater contribution to baseflow Depending upon the researcher and the school of thought, the values for baseflow per catchment varies widely without guidance which number would be appropriate to relate to groundwater contribution to baseflow. Furthermore, the natural baseflow is usually significantly higher than the low flow requirements to maintain the ecological Reserve requirements. The correct definition of the groundwater component of the Reserve is: Reserve(%) = EWRgw +BHNgw Re 100 (2) where Re = recharge, BHN gw = basic human needs derived from groundwater, and EWR gw = groundwater contribution to EWR However, there are several problems even with using the low flow requirements as guidance, as the Reserve is expressed as percentage of recharge, a highly variable and uncertain parameter, and both recharge and EWR gw are derived at catchment scale and are not aquifer specific.

7 2.2 Aquifer Stress The present status and recommended categories for groundwater are defined based on the aquifer stress concept, which is the ratio of groundwater abstraction vs. recharge, as outlined in the GRDM Manual (Dennis et al., 2011). The issues arising out of this concept are twofold: The aquifer stress does not take into account the ecological requirements nor the impact of other discharge processes. Hence, the results cannot be compared across different aquifer settings. An aquifer with significant contribution to the ecological Reserve could be over-exploited with an aquifer stress index of less than 40% (PS C), while a confined aquifer with off sea discharge could be sustainable with an aquifer stress of more than 90% (PS E). The calculation of aquifer stress uses mean annual recharge, without consideration of the natural annual fluctuations and the actual yield potential of the aquifer. This results in over-abstraction for some aquifers in the arid climate with period rainfall and recharge, and under development of confined aquifers with huge storage capacity and lag time of several years to decades. 2.3 Scale The ecological Reserve is either determined per quaternary catchment (rapid determination) or at specific points within the water body, viz. EWR sites (intermediate and comprehensive determination). The Groundwater Reserve is usually determined per quaternary catchment or even larger resource unit (see case studies in Section 3). However, both scales are not applicable to the groundwater contribution to the ecological Reserve, which is usually a discrete discharge along specific river reaches or via springs. Hence, there is no need for a Groundwater Reserve, if the next surface water body and possible discharge point is kilometers away from an abstraction point. The relevant scale differences between surface water bodies and groundwater that need to be considered during the Reserve determination process, and even more so for the classification and the development of RQOs are given below: Aquifer boundaries mostly do not coincide with surface water catchment boundaries, especially for fractured aquifers and confined aquifers; Groundwater discharge occurs at distinct areas, such as river reaches or springs, and is not homogenously distributed across the catchment or aquifer; Groundwater flow is significantly slower than surface water flow, which impacts on the seasonal pattern of groundwater discharge as well as water availability for users.

8 3 Case studies The issues around the current implications of the Groundwater Reserve concept are discussed on three case studies with different climatic and aquifer settings. 3.1 Artesian, confined aquifer A Reserve determination was required for the licence application by the Oudtshoorn municipality to abstract water from the artesian, confined Peninsula Aquifer south of Oudtshoorn. A slightly modified methodology was developed and implemented for this study due to the fact that the standard methodology only applies to unconfined aquifers that are in direct contact with the surface water body. Based on the results of that study, the following considerations for the Reserve determination of the groundwater contribution to the Reserve in artesian basins need to be taken into account (Riemann and Blake, 2011): Basic Human Needs component can be neglected for the artesian aquifer as this need is usually provided from shallower unconfined aquifers or rivers. Rejected recharge and overspill in the aquifer outcrop area (i.e., unconfined portion) contributes to river flow, which might be impacted by abstraction if the zone of influence reaches the unconfined portion of the aquifer. Discharge zones from the deep artesian basin are limited to hot springs (where flow paths can be mapped) along with possible diffuse discharge along fault-bounded boundaries of the artesian basin. The storage capacity for the confined aquifer is sufficient for managing the aquifer over a longer time period than 1 or 2 years, as usual for unconfined aquifers and dams, without impacting on the environment. It is suggested that the licensing and Groundwater Reserve determination process in artesian basins focuses on the development of site specific and enforceable RQOs, rather the determination of an annual value of permissible abstraction and volumes to be reserved in the aquifer. 3.2 Letaba, Umzimvubu to Keiskamma The DWA initiated Groundwater Reserve studies for selected Water Management Areas. Due to the scale of the areas under investigation, the level of Reserve determination was usually a desktop level. For the Letaba catchment, some information on surface water ecological requirements was available for selected sites, while for most of the catchments no information was available. Most of the rivers in the Letaba catchment are seasonal or ephemeral rivers and baseflow is usually set to zero. Hence, assumptions on low flow requirements had to be made.

9 The groundwater Reserve determination and GRDM assessment for the Mzimvubu to Keiskamma WMA was undertaken at an intermediate level, as the spatial scale does not allow for a comprehensive level. Most of the delineated resource units comprise several catchments of similar geological / hydrogeological and land use characteristics. Hence, the results of this Reserve determination provide a guideline for groundwater management on a regional scale, but do not allow for local and site specific differences. The Reserve determination with respect to the groundwater component of the ecological Reserve and Basic Human Needs Reserve was based on the maintenance low flow requirements per quaternary catchment and the total population living in the area. This resulted in a range of the Reserve requirements between 3% and 71% of recharge for the different resource units with an average of 21% of recharge for the study area, confirming the problem with using the standard aquifer stress as index for the present status. 3.3 Olifants Doorn A water resource classification study was recently completed in the Olifants-Doorn WMA (DWA, 2012) with a subsequent study to determine RQOs near completion (DWA, 2013). Groundwater input into the classification process was prepared on a quaternary catchment scale and not further considered in the classification scenarios. The outcome of the process was not suitable to be used in the determination of RQOs due to the difference in scale and inadequate data. The RQO study provided meaningful RQOs for groundwater in selected priority areas, where sufficient information about the aquifer status, current and future users, and the receiving environment was available. It was decided to only gazette the RQOS and not to gazette the recommended categories for groundwater, as The Recommended Category (RC) for most catchments requires a decrease in abstraction, as it constitutes an improvement from the Present Status; e.g. from a PS of B to a RC of A. This would require a curtailment of current allocation and abstraction with significant impacts on the agricultural sector and domestic supply. The water supply for a number of towns depends upon the abstraction of groundwater, which is not taken into account in the assignment of the RC The potential of future groundwater development within the WMA, as outlined in several previous reports (e.g. Olifants River Basin Study, WODRIS, Clanwilliam Dam Raising Study, All Towns Reconciliation Strategy Study), was not taken into account. The gazetting of the current RCs would foreclose these identified options for groundwater development and negate the strategic intent by the Department of promoting groundwater as future water supply option.

10 4 Implications for groundwater management The implementation of the standard methodology for classification and Reserve determination to groundwater resources often results in undesirable outcomes and is one of the inhibiting factors for sustainable groundwater development, as some of the aspects and current methods are not applicable to groundwater and not appropriate for implementation. The current separation of the Groundwater Reserve determination process from the ecological Reserve determination emphasizes this pitfall of the process and methodology. The slow implementation of the NWA and the discrepancies between the different regulations and guidelines with respect to groundwater and surface water provisions limit the potential groundwater development and unduly delay licences, urgently needed to eradicate water supply backlogs. 5 Proposed way forward The following steps can be undertaken immediately for all future Groundwater Reserve studies and licence applications: Integrate groundwater into ecological Reserve determination studies Utilise minimum low flow or maintenance low flow conditions as determined by ecological Reserve determination studies for calculating the groundwater component Waive the requirement for a preliminary Reserve determination for licences that have clearly no impact on surface water bodies Focus studies on the preliminary determination of resource quality objectives to guide catchment management and licence conditions The focus of groundwater RQOs in this context is twofold; i.e. to support the ecological requirements of the receiving surface water bodies, as determined by the surface water RQOs, and to ensure adequate water quantity and quality for the direct and indirect users of the groundwater resource.

11 6 References Conrad, J, A Matoti & S Jones (1999). Aquifer Classification Map of South Africa DWA (2007). The Development of the Water Resource Classification System (WRCS). Department of Water Affairs, South Africa, Chief Directorate : Resource Directed Measures. DWA (2010). Regulations for the Establishment of a Water Resource Classification System. Regulation 810, published in Government Gazette No , 17 September 2010 DWA (2011). Procedures to Develop and Implement Resource Quality Objectives. Prepared by Institute of Natural Resources on behalf of the Department of Water Affairs of South Africa. Directorate : RDM Compliance DWA (2011). Determination of the Groundwater Component of the Reserve: Mzimvubu to Keiskamma WMA Final Report: Western Portion. Prepared by Umvoto Africa (Pty) Ltd on behalf of the Department of Water Affairs, South Africa. Directorate : Reserve Requirements. DWA Report No. RDM/WMA12/02/CON/INT/0312 DWA (2012). The Classification of significant Water Resources in the Olifants-Doorn WMA Final Project Report. Prepared by BlueScience Consulting cc on behalf of the Department of Water Affairs, South Africa, Chief Directorate : Resource Directed Measures. DWA Report No. DWA (2013). Development of RQOs in the Olifants-Doorn WMA. Prepared by Umvoto Africa (Pty) Ltd in association with Southern Water Ecological Research and Consulting cc on behalf of the Department of Water Affairs, South Africa. Directorate : RDM Compliance. DWA Report No. DWA (2013), A Framework for the Amendment of Groundwater Classification Guidelines (2007). Department of Water Affairs, South Africa. Directorate : Water Resource Classification; June 2013 Mavurayi, A (2011). Unpacking the Groundwater Reserve. In: Proceedings Groundwater: Our Source of Security in an uncertain Future. Biennial Conference of the Ground Water Division (GWD) of the Geological Society of South Africa (GSSA), organised in association with the International Association of Hydrogeologists (IAH), September 2011, Pretoria Parsons, R (1995). A South African Aquifer System Management Classification. Report to the Water Research Commission of South Africa. WRC Report KV 77/95 Riemann, K. and D Blake (2009). Groundwater Reserve Determination for current and potential Wellfield Development of TMG Aquifers The undertaking of the Rapid Reserve Determination for the Oudtshoorn Municipality. WRC Report K8/871/1, Water Research Commission, Pretoria, December 2009 Riemann, K. (2011). Groundwater Reserve Determination for a confined, artesian Aquifer An Oxymoron? In: Proceedings Groundwater: Our Source of Security in an uncertain Future. Biennial Conference of the Ground Water Division (GWD) of the Geological Society of South Africa (GSSA), organised in association with the International Association of Hydrogeologists (IAH), September 2011, Pretoria