Hydrological Sciences—Journal—des Sciences Hydrologiques, 44(4) August 1999 5 ] 7 Special issue: Barriers to Sustainable Management of Water Quantity and Quality

Biophysical demand and sustainable water resources management: an Australian perspective

DHIA AL BAKRI, JENNY WICKHAM & MOSHAREF CHOWDHURY Orange Agricultural College, The University of Sydney, PO Box 883, Orange, New South Wales 2800, Australia e-mail: albakri@oac.usyd.edu.au

Abstract To develop a sustainable management system of any water resource, it is essential that a balance between the demand of the natural biophysical system and the need of the socio-economic development is achieved. The main challenge that water managers grapple with is how to reconcile the long-term environmental objectives with the short-term political, social and economic needs. Since the biophysical resources underwrite all socio-economic activities, it is imperative that the long-term health of surface water and groundwater systems be the primary driver for sustainable management of water resources. If the environmental need to sustain the ecological values of water is overlooked, then serious water quality problems will arise and the natural aquatic ecosystem will deteriorate to a level such that both social and economic developments become unsustainable. Case studies on water quality and recent water reform initiatives in Australia are discussed in this paper to demonstrate the paramount importance of the biophysical system for sustainable water resources management.

Une perspective australienne sur les besoins biophysiques et la gestion durable des ressources en eau Résumé Pour gérer durablement n'importe quel système de ressources en eau, il est nécessaire d'atteindre un équilibre entre les besoins biophysiques du système et la demande socio-économique. Le principal défi que les gestionnaires de l'eau doivent affronter est de concilier les objectifs environnementaux à long terme avec les objectifs sociaux, économiques et politiques à court terme. Comme les activités socio-économiques s'appuient sur les ressources biophysiques, il est nécessaire que la bonne santé à long terme des eaux superficielles et souterraines soit le principal souci d'une gestion durable des ressources en eau. Si l'on néglige la dimension écologique, de sérieux problèmes de qualité se poseront et les écosystèmes aquatiques se détérioreront à un point tel que le développement socio-économique en sera affecté. Les études de cas concernant la qualité de l'eau et les récentes initiatives de réforme menées en Australie qui sont évoquées dans cet article visent à démontrer l'importance primordiale des systèmes biophysiques pour une gestion durable des ressources en eau.

INTRODUCTION

The quantity and quality of surface water and groundwater resources are functions of a dynamic and complex interaction of the biophysical system, and the social and economic systems. It is, therefore, essential that the needs, constraints and capacities of each of the above three systems be taken into consideration in order to ensure long-term sustainability of any given water resource. There is increasing recognition that these systems are inter-linked, and that both social and economic objectives are

Open for discussion until 1 February 2000

518 Dhia Al Bakri et al.

dependent on the long-term health and sustainability of the natural environment. Since the biophysical factors and resources (climate, geology, minerals, soil, water, fauna, flora) underwrite all developments, the socio-economic activities can only be viable when the natural resources they depend on are sustainable (Al Bakri & Mclnnes, 1999; NSW EPA, 1997). In other words, if the environmental demand of the biophysical system is not sustainable, then the socio-economic development would also be unsustainable. Although each of the above two systems presents diverse and complicated challenges to the development of sustainable water resource management, overlooking the needs of the biophysical environment is by far the most critical barrier to sustainability (Al Bakri, 1998; Allan & Lovett, 1997). According to Maser (1997), the key biophysical impediments to sustainability of water resource management are: violating the biophysical principles governing nature's dynamics; making the ecosystem more fragile when we alter it; ignoring reinvestment in living systems as we reinvest in business; and disregarding the inherent limitations of the ecosystems.

The purpose of this article is to demonstrate that sustainable water resource management is untenable unless the needs, constraints and resilience of the biophysical system of water are carefully considered and satisfied.

WATER RESOURCE MANAGEMENT IN AUSTRALIA

Historical overview

The critical characteristics of surface water and groundwater in Australia are their temporal and spatial variabilities. Most of the water resources are well away from the more productive agricultural land. Australia's waters also vary between too much (floods) and too little (droughts) and they are controlled by the most variable rainfall and streamflow in the world (Smith, 1998). Australia has the least rainfall as runoff, the least water in rivers, and the smallest area of permanent wetlands of all the populated continents (NSW EPA, 1997). The management of water resources in Australia has been, until recently, driven by socio-economic imperatives by focusing on regulating water for various agricultural, domestic, energy, transportation and recreational uses. Traditional water management has resulted in the alteration of natural flow regimes to the extent that many ecological processes have been severely disrupted and considerable water quality problems have emerged (Allan & Lovett, 1997). These emerging water quality issues are currently presenting planners and managers with additional challenges in terms of providing good quality water to meet the demands of the different water users and to satisfy, at the same time, the growing community aspiration for conservation and environment protection.

In recent years, there has been growing recognition that water management needs to achieve a balance between making allocations to the environment and consumptive use in order to enhance and restore the health of the water dependent ecosystem. Incorporating the principles of ecologically sustainable development (ESD) has become an increasingly important aspect of the water resource management process (NSW EPA, 1997). However, despite the recent changes in policy and attitude in

Biophysical demand and sustainable water resources management 519

relation to water management, efforts to achieve sustainability have, to date, met limited success (Smith, 1998; Allan & Lovett, 1997) for the following reasons: (a) The socio-economic agenda, rather than the environmental need, is still the main

driver for many policies and management strategies. (b) The inherent demand and constraints of the natural ecosystems have not been

adequately considered in the management process, either due to lack of appropriate understanding of their complexity or because they are politically or socially unpalatable.

(c) The native ecosystem is now so altered that some of the damage is very serious and, in some instances, probably irreversible. Therefore, significantly more time and resources are required if sustainability of the biophysical system is to be restored.

(d) The causes of the emerging water quality problems have probably been misdiagnosed, and subsequently the remedial actions adopted have either been ineffective or focused on treating the symptoms rather than the causes.

The Murray-Darling basin and NSW water reforms

The Murray-Darling basin (MDB) in New South Wales (NSW), Australia, is the largest river system in the country and is the most important agricultural region in Australia. Water use in the MDB was increased from approximately 50 Gl in 1910 to 750 Gl in 1993/1994. It is now being recognized that the growing demand on water must be controlled because the MDB has a limited supply. This demand has reached such a level that there is serious conflict between the various human uses and the main­tenance of sustainable ecosystems. There is also widespread evidence that the water quality is declining and that the existing arrangements do not protect the health of river and groundwater systems sufficiently (DLWC, 1998). The Murray-Darling Basin Ministerial Council (MDBMC), which is an intergovernmental body set up to manage the water resources of the basin, has recognized that there is an urgent need to reform the management of the water resources, to create a more efficient and effective system and, at the same time, to satisfy the ESD principles. In 1995 the MDBMC made a mile­stone decision in water management reform. The new water policy decision recognized that the natural environment is a legitimate user of water, and must have an appropriate share of water to protect the health of natural systems. The policy was based primarily on limiting all further water diversions from the rivers of the basin to be consistent with the level of development which existed in 1993/1994. As a result, a cap on water use was applied on water extraction in the MDB. The water sharing arrangements of the MDBMC and the cap defined the limits within which the State Governments must manage their respective water resources within the basin (DLWC, 1998).

In response to the MDBMC policy framework, the NSW Government released a major water reform package in 1995, followed by a second package in 1997. The main features of the Water Reforms are to: - achieve a better balance in water use between users and the environment; the

maintenance of the fundamental health of river and groundwater systems and processes is a prior right to water over extractive uses;

520 Dhia AI Bakri et al.

- develop long-term objectives for environmental flows and water quality through a public consultation process;

- link priority action to an assessment of stress for rivers and risk for groundwater; - develop a community-based management plan for each valley; and - ensure that any proposed changes to the current water sharing arrangements should

clarify, and, wherever possible, not act to diminish, current water users' rights. The Government's expectation was that the Water Reforms will establish an

appropriate balance between maintaining natural processes and supplying humans, industrial and agricultural enterprises with necessary water. It is believed that the above strategies will lead to outcomes which achieve the best long-term economic, social and environmental productivity from our water resources (DLWC, 1997, 1998).

The MDBMC policy framework and NSW Water Reforms represent a turning point for water management in Australia. This management system considers, for the first time, that the environment is a legitimate user of water and that a balance between the environment and consumptive users should be addressed (Allan & Lovett, 1997). The major shortcoming of these reforms, however, is the lack of a proper under­standing of the inherent characteristics and constraints of the biophysical system. Furthermore, the implications of the proposed water reforms on the environmental flow and water quality of each river or groundwater system were not well understood. It was apparent, during the community consultations carried out in 1998, that the Government did not have the scientific rationales to justify the environmental assumptions used in developing many of the policies and management strategies. As a result, the Government had to give in to lobby groups and make changes to the reforms to allow more flexibility for undertaking socio-economic development without considering the negative implications for the biophysical system. Early indications suggest that the proposed reforms will not lead to sustainable management of water resources for the following reasons:

- although the ESD principles have been considered in developing these reforms, the socio-economic imperatives are still the main driver;

- community support of the reforms will not be forthcoming because it will be extremely difficult to reconcile the competing demands of the different water users in the absence of well substantiated ecological, environmental and hydrological indicators and models; and

- the lack of good models to assess the impact of various water sharing scenarios on the aquatic ecosystems, flow, water quality and socio-economic development mean that managers will often make decisions that are not sustainable.

WATER QUALITY ISSUES

The scant regard for the environment and the over-commitment of water since European settlement have created considerable water degradation problems such as salinity, rising water table and algal blooms. Most of these water quality problems are related to land degradation resulting from poor land management practices over the past 200 years. It is believed that land and water degradation problems represent a serious threat to the agricultural industry. Indeed, large agricultural areas in inland

Biophysical demand and sustainable water resources management 521

Australia are being inappropriately used and many agricultural practices are simply unsustainable (Smith, 1998). It is not only the quantity of water that is the problem facing inland Australia, quality deterioration of surface water and groundwater is increasingly becoming a major concern to water users and managers. Two case studies from dryland agricultural catchments in inland Australia, which were carried out by the authors, are presented in this paper to provide a context to the above issues.

Case study 1: dryland salinity

In this study the authors investigated the effectiveness and sustainability of current management practices to control dryland salinity in Barneys Reef and Yahoo Peaks catchments which are situated in the Central West region of NSW, Australia. The impact of dryland salinity is felt not only on the farm; salinity generates downstream effects that impact on a wide cross section of the rural community (Price, 1993). The accumulated capital loss due to secondary salinity of soil and water in Australia is estimated to have been about Au$450 million in 1989 and the annual gross value of lost production was about Au$ 102 million (Peck, 1993). The occurrence and degree of severity of dryland salting depend on the interaction of a host of factors including geology, hydrogeology, geomorphology, soil, climate and past and present land use practices (Jenkins, 1981). Dryland salinity, however, is primarily a hydrogeological problem where a rising saline water table leads to soil salinization and seepage into the landscape causing surface water salinization (Thorburn, 1996). Therefore, a good grasp of the hydrological and hydrochemical process within a landscape is fundamental to the understanding of where and why dryland salting occurs. Without such an understanding, there is an increased risk that the adopted remedial actions will not achieve the desired effect (Thorbum, 1996; Salama et al, 1993).

Barneys Reef catchment Barneys Reef catchment, an 810 ha property which runs a self replacing merino stud for wool production, is drained to the Talbragar River which is one of the main tributaries of the Macquarie River system. The latter is one of the main rivers in the Murray-Darling basin. A low lying area of approximately 100 ha, in the centre of the catchment, shows significant effects of soil and water salinization. The central drainage line, which runs through the salt affected area, follows the fault zone in this vicinity. A natural spring, known to be in existence in this area for over three generations, has always produced salty water, thus salt in this area is a historical phenomenon. However, the salinity affected area has expanded further from the central drainage/fault zone in recent years. A salinity management programme established in 1990, includes property planning, planting salt-tolerant trees and deep-rooted pastures at both recharge and discharge sites, structural works (earthworks) to divert surface water, and fencing of the salt affected area to keep stock out (Nicholson &Seis, 1993).

Based on the hydrochemistry and monthly monitoring of the water table level carried out by the authors from a network of 20 piezometers, a relatively shallow groundwater system and a deep groundwater system can be identified. The shallow groundwater system, with depths to water table ranging between a positive head of

522 Dhia Al Bakri et al.

+2 m (above ground surface) to -4.40 m (below ground surface) tends to be brackish to saline with average electrical conductivity (EC) values ranging from 1,0 to 5.9 dS cm"1. The sodium concentrations in this groundwater system range between 296 and 945 mgf'. The water samples collected from the deeper aquifer were found to be saltier than the shallow groundwater system with average EC values of 7.7 and 7.2 dS cm"1 and sodium concentrations of 1013-1267 mg l"1. The permeable nature of the fault along which the salt affected area has developed is believed to be acting as a conduit for upward leakage of water from the deeper saltier aquifer into the relatively fresher shallower water system, i.e. mixing of waters in this catchment is significant. The saltier deeper groundwater system is believed to be part of a regional system that is mainly recharged through areas outside the catchment.

The results of the monitoring of the piezometers (August 1992-March 1996) did not show any significant trends in terms of lowering the water table level or reducing salt levels in the water table (Figs 1 and 2). The depth of the shallow water system has

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Biophysical demand and sustainable water resources management 523

fluctuated greatly over the five years and may be the result of seasonal variation in climatic conditions and land-use practices. Based on this finding, it can be argued that the existing salinity control measures are not contributing to a tangible lowering of the water table level and subsequently the salt concentration in the catchment. Taking into consideration the significant leak from the saltier and deeper aquifer into the relatively fresher and shallower groundwater system, it is believed that the salinity management system currently in place is neither effective nor sustainable. This is because the existing management options were developed on the assumption that the salinity was primarily controlled by a locally recharged local groundwater system and that the influence of the regionally recharged deeper aquifer was insignificant. Based on the findings of this investigation, the following measures should be considered for controlling salinity in this catchment: introducing deep-rooted trees and applying engineering measures in the main recharge sites of the regional aquifer to reduce the rate of recharge to the deeper water system, planting additional trees and deep-rooted plants in the discharge sites as well as in sites at risk of salinization within the catchment to increase the rate of évapotranspiration and lowering of the water table, and rehabilitating the salt-affected areas by growing salt-tolerant pastures for conservation and productivity purposes. The design, feasibility and cost-effectiveness of these measures should be the subject of a further research project.

Yahoo Peaks catchment Yahoo Peaks catchment covers an area of 3000 ha and is drained by the intermittent Iona Lodge Creek which is one of the tributaries of the Macquarie River. At Yahoo Peaks catchment, mixed farming operations are dominant, principally cattle grazing and cereal cropping for wheat and oats (Nicholson, 1991). The main salinity management strategies in place, developed in 1989, include planting trees and deep-rooted perennial pasture at the recharge and discharge sites and a programme of structural works including earthworks and fencing.

The results of the hydrochemistry investigation and the monitoring of the piezometer network (15 piezometers) carried out by the authors also indicated that two groundwater systems exist in this catchment. The shallow groundwater system ranges in depth between 1.6 and 5.0 m. This system is dominated by sodium chloride waters (sodium: 581-1092 mg l"1 and chloride: 1720-3320 mg l"1) and has a relatively high salinity with average EC values ranging between 5.5 and 14.3 dS cm"1. The deeper groundwater system is significantly fresher than the shallow system with average EC values varying between 1.3 and 2.5 dS cm"1. The water chemistry in this system is dominated by sodium bicarbonate. Evidence from present and previous investigations suggests that the shallow groundwater system is locally recharged primarily via the fractured granite and through the permeable soils of the basalt (Nicholson, 1991; Wickham, 1998). On the other hand, the deeper groundwater system is believed to be part of a regional system and thus it is mainly recharged through areas outside the catchment. It is believed that the highly permeable nature of the fault or fracture zone, along which the salt-affected area is developed, allows for easy movement of water. The mixing effect resulting from the upward leakage along the fault zone decreases salt concentration in the shallow water system. The monthly monitoring of the piezometers (June 1995-May 1996) shows a lowering trend of the water table and a reduction in the salt levels (Figs 3 and 4). Unfortunately, there are no historical monitoring data of the

524 Dhia Al Bakri et ai

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water table in this catchment prior to this investigation. Therefore, the database available is rather limited and does not provide a significant insight into the long-term trend of the water table level and salinity in the catchment. The lowering trend observed may be due to seasonal and short-term fluctuations in climate conditions. However, taking into account the nature of the hydrogeological system and the geology of the catchment coupled with the observed lowering trend of water table, one can cautiously argue that the management strategies adopted for Yahoo Peaks to control the salinity problem appear to be working. Needless to say, long-term monitoring data of the water table are required to test the validity of this hypothesis. Another measure that should be considered to lower the water table is to use the fresher groundwater from the deeper aquifer for irrigation. This approach will enhance the effectiveness and sustainability of the current management system by further lowering of the shallow water table. This management option needs to be investigated in a further research project.

Biophysical demand and sustainable water resources management 525

Implications for sustainable management This case study has confirmed the view that there is no single hydrogeological model that can explain causes and processes controlling salinity in all catchments. Although there is some similarity between the two investigated catchments, subtle differences in the hydrogeological and geological setting were responsible for creating different processes causing salinity in each catchment. To reduce the risk of applying inappropriate management strategies, catchment-specific hydrogeological and geological investigations should be undertaken to ensure that the adopted management options are both effective and sustainable.

Case study 2: eutrophication and algal blooms

The cost of algal blooms in Australia runs into millions of dollars annually (NSW EPA, 1997). The blue-green algal blooms (Cyanobacterid) have a wide range of social, economic and environmental impacts. Some species produce toxins which are harmful to humans and livestock (Verhoeven, 1993). This case study is based on a water quality investigation conducted by the authors in the water supply of Orange City, Central West region of NSW, Australia. The main water reservoir of the catchment (Suma Park) has experienced frequent algal outbreaks in recent years. In addition to aesthetic, environmental and cost implications, the algal blooms have led to the development of unpleasant odour and taste in the drinking water (Al Bakri et al., 1995). The aim of the study was to investigate the causes of the problem and to develop sustainable management strategies to control blue-green algal blooms in the reservoir and to protect the water quality in the catchment.

Although algal blooms are essentially part of the natural processes, they have been exacerbated in recent years as a result of mismanagement and degradation of the land and water resources. Blue-green algal outbreaks depend upon the interaction of a wide range of biophysical processes and socio-economic factors such as nutrient levels, particularly phosphorus (P) and nitrogen (N), flow, temperature, light, aquatic ecosystem balance, land use and catchment management. It is widely accepted, however, that nutrient level, particularly P, is the dominant limiting factor of algal growth in freshwater systems (Grace et al, 1997; Harris, 1994). Consequently, manipulation of the P concentration is considered the most critical management tool to control algal growth in inland waterways (Hecky & Kilham, 1988; Harris, 1994). The conventional view suggests that most of the P in Australian inland waterways comes from fertilized topsoil, agricultural runoff, and/or from point sources such as sewage and industrial effluents (Bek & Long, 1994; Verhoeven, 1993). Based on this understanding, current strategies to manage algal blooms in rural Australia have focused on reducing the P entering waterways from these sources (Verhoeven, 1993). There is now, however, mounting evidence to suggest that the concepts and assumptions underpinning this conventional understanding are not entirely valid for many turbid Australian rivers.

As shown in Table 1, the water supply is a high nutrient input system with P and N concentrations reaching, on most days, levels significantly higher than the Australian Guidelines (ANZECC, 1992) for concentrations at which excess algal growth problems in reservoirs and streams have been known to occur. The analysis of study results have indicated that superphosphate fertilizers and point sources (sewage and industry effluent)

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Table 1 Nutrient concentrations in Orange water supply catchment (jig l"1).

Nutrient

Total P: Reservoir Stream Reactive P: Reservoir Stream Total N: Reservoir Stream

Samples analysed

78 220

36 104

78 222

Mean

61 86

21 33

715 960

Median

50 60

20 30

600 900

Min.

20 20

<10 <10

300 200

Max.

260 590

80 85

1600 2400

Standard deviation

36 72

15 18

316 408

Australian guidelines

5-50 10-100

NA NA

10-500 10-750

were not the primary sources of P in the catchment (Chowdhury & Al Bakri, 1998; Al Bakri & Chowdhury, 1997). Evidence from this study and other recent studies carried out in other Australian inland waterways (Oliver et al, 1993; Caitcheon et al, 1995; Murray, 1996; Donnelly et al, 1996), indicate that the background P in the naturally P-rich soils derived from Tertiary basalt and other volcanics in the catchment was the primary source of P in the waterways. The P which is bound up with fine suspended sediment is transported to the waterways from gully and stream bank erosion (Chowdhury & Al Bakri, 1998; Al Bakri & Chowdhury, 1997; Wasson et al, 1996; Murray, 1996). Internal loading processes were considered responsible for releasing part of the particulate P from the bottom sediment to the water column as dissolved P which becomes available for algal use (Kilham & Kilham, 1990; Murray, 1996).

Based on this understanding, the conventional catchment-wide management strategies to reduce superphosphate fertilizer application, although useful for many other conservation purposes, may not be effective in terms of reducing eutrophication and controlling algal blooms. The management implication of this finding is that sustainable management of eutrophication and algal blooms should focus on the following options: - reducing input of sediment from stream bank and gully erosion to reduce or

eliminate external sources of P; - manipulating the water bodies of the dams to reduce internal loading of P from the

bottom sediment. - biomanipulating the aquatic ecosystem to restore the ecological balance in the

reservoir and to reduce nutrients available to the algae. This option, which needs to be considered in a further research project, may prove to be the most effective and sustainable strategy to control algal blooms in the long term.

CONCLUSIONS

As the biophysical (natural) processes are the causal factors which influence and control the inherent characteristics and constraints of any given water resource, a careful consideration of the biophysical need is fundamental to sustainability. The findings from the above case studies and other recent research further support the hypothesis that a good grasp of biophysical processes is essential to the development of

Biophysical demand and sustainable water resources management 527

environmentally sustainable and economically viable management strategies of water resources. Therefore, water resource management should have the primary aim of satisfying environmental needs and sustaining the ecological values of water-dependent ecosystems. Indeed, the management or treatment of the social, cultural, political and economic impediments has very little value in terms of sustainable water resource management if the tolerance and demand of the biophysical system are overlooked or ignored. The socio-economic aspects of the management process should, therefore, be considered in the light of the biophysical constraints. To maintain sustainability of water systems, the will to direct energy and resources towards living within the constraints defined by ecosystem sustainability and not by political or economic desires must be found (Maser, 1997). Such an approach will ensure that the subsequent socio­economic aspects of the management process will be cost-effective and viable. As the case studies demonstrated, sustainable water resource management cannot be attained if the biophysical processes are not well understood. Therefore, the biophysical need, rather than the socio-economic imperative, should be the primary driver of sustainability.

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