CHAPTER 2 – LITERATURE REVIEW
Part of the reality of being a South African citizen, is that large portions of the country are dry and providing as well as obtaining sufficient water resources will always be a challenge in the country. If water misuse (uncontrolled leaks and excessive application, both indoors and in the amenity landscape) continues at the current rate in South Africa, it is predicted that many parts of the country will face excessive water shortages within the next few years. The Western Cape has experienced water shortages during 2015-2018 (Masante, McCormick and Vogt, 2018). Many different interventions are being proposed and implemented to address this potential water crisis such as legislation (Water Services Act, 1997), guidelines (NWRS2, 2013) and voluntary associations encouraging water reduction (Green Building Council of SA, 2014). Despite the variety of interventions which impact a wide range of different communities and has the ability to influence everyone in some way, water is still in short supply, with water restrictions in place across different parts of the country on an ongoing basis.
Currently, the amount of water applied to amenity landscapes is consistently more than baseline plant water requirements. This may be as a result of non-uniformity in application of irrigation systems (Kjelgren, Rupp and Kilgren, 2000) or indiscriminate water application. To address the excessive and wasteful use of water in amenity landscapes it is important that mechanisms to reduce water use should be studied.
An understanding of the value of water depends on several components, namely “the volume of water supplied, where the water is supplied, when it is supplied, whether the supply is reliable, and whether the quality of the water meets the requirements of the intended use” (US EPA, 2013). All these aspects are relevant when considering requirements of a watered amenity landscape.
Water availability and use within the urban environment, as has been traditionally managed in the past, can no longer continue. Increasing demand from residents, industry, business and other water users is placing strain on water resources in terms of availability, storage, transportation, supply and management. Added to this is climate change and associated variables that impact on water availability.
Climate change will impose challenges on our fresh water sources. Most of South Africa is likely to become drier and hotter over time. The storage infrastructure on our river systems is almost maximised and storing additional water is becoming a major challenge (National Page 14 of 409 Business Initiative, 2011). This is exacerbated by the fact that South Africans use more water than our catchments are able to replenish. Lack of sufficient water could impact business processes and function (more particularly wet industries), and this could have a significant impact on South Africa’s industrial and economic competitiveness (National Business Initiative, 2011). As a result, South Africa has resorted to balancing supply and demand by transferring water across catchments on a scale not common elsewhere in the world. According to the National Water Act (Act No. 36 of 1998), government is the custodian of all water sources in the country. Water catchment areas serve multiple users. It is therefore critical that the South African government effectively negotiates, regulates and distributes water among equally deserving users (National Business Initiative, 2011). Added to this, demand for water in the large and rapidly growing areas of Johannesburg-Pretoria (Gauteng), Cape Town (Western Province) and Durban (Kwazulu-Natal), is compounding the requirement for additional water supply (Binns, et al., 2001). All these aspects will impact on available water for amenity landscapes.
Amenity plant water use, plant species linked to specific hydrozones, as well as environmental climatic and management factors linked to amenity landscapes in South Africa, have not been extensively discussed or researched. Moreover, there is little scientific data available for such studies within the South African context. As a result, many references available are either policy or recommendations that are mostly scientifically unconfirmed (e.g. data quoted by the Rand Water, Water Wise brand).
Strategies to reduce water use
Many strategies to reduce water use involve dissemination of information and tools to end users through various media/forms (Rand Water, 2017). Water demand management that focusses on aspects such as leak detection, retrofitting, pressure reduction techniques etc. has also been implemented. All Water Service authorities are required to educate end users on water conservation (Water Services Act, 1997) and as a result many authorities and municipalities in South Africa have started to address this matter at various levels. The government’s ‘Blue drop status’ that commenced in 2009, is awarded to Water Service Authorities and also to municipalities (Department Water and Sanitation, 2015). It addresses a wide range of water related activities and considers amongst others the extent that they have engaged with and educated end users on water conservation (Department Water and Sanitation, 2015). The Department of Water and Sanitation has also proposed that a “No drop” reporting and awarding system focusing more specifically on water conservation and water demand management, be implemented, however this has yet to fully materialize and be reported upon (Tancott, 2013). The National Water Resource Strategy 2 (NWRS2) notes the need to implement numerous practical, educational and awareness initiatives that will contribute towards water conservation and water demand management (NWRS2, 2013). Devi (2009) indicates three broad methods that are used to promote outdoor demand management programs. These methods being, communication and education, economic incentives as well as best practice, and benchmarking. This research study addresses the latter methods.
Since 1997 Rand Water has made huge contributions in South Africa and especially in the Gauteng Province with its Water Wise campaign researching, educating, and demonstrating of practical methods of how water conservation can be applied. Predominantly this was focused on the horticultural, landscaping and gardening industry but has since spread its attention to include other areas. This position was reinforced in 2017, with their campaign receiving the International Water Association award for PIA 2016 Marketing and Communications Award as well as the PIA Grand Award 2016 (Rand Water, 2017). Added to this, several organisations (e.g. Green Building Council of SA, 2014) and non-governmental organisations (e.g. World Wildlife Fund, 2018) are in their own capacity attempting to influence a radical water use ethic and culture across South Africa as part of their operations. Despite these attempts by many role players, there is still a need for greater input to conserve water in order to reduce wastage and demand.
Water conservation measures in times of drought
In 2009, Hoy made several recommendations with regard to proactive and reactive water restrictions for amenity landscapes. It included estimated water savings for each level of restriction (Hoy, 2009). These were never implemented. However the reality is that droughts are still periodically experienced. When droughts impact the water storage below pre-set levels for each storage facility, many political and/or water regulatory structures announce various forms of restrictions, often seemingly at the last minute. They are seldom phased in over a long period of time, as stated by Hoy (2009) and echoed by Carrow (2006). This same scenario was again repeated in numerous regions of South Africa in the drought of 2016 – 2018. Water restrictions in most instances involve dictating times and frequencies of using any form of outdoor watering device/method and are usually imposed for a specific period of time based on water availability (Devi, 2009). None of the current methods (restrictions) specifically indicate how much water can be saved through these initiatives either in buildings or in the amenity landscape. For the Green Industry, this is contrary to what was proposed by Hoy (2009) where specific restrictions were proposed together with the anticipated water savings, based on international benchmarking and South African Green Industry input.
Generally, water restrictions in themselves do not change long-term water use habits, as the restrictions are mainly implemented only during times of crisis. This is primarily because the restrictions themselves do not address the underlying issues, but merely the use factor of water itself (Devi, 2009; Hoy, 2009). This points to a potential gap in the manner in which amenity landscape water is used and managed.
Impact of water use on amenity landscapes
Amenity landscapes and the Green Industry in general are dependent on water. Plants require water to grow in a landscape even if they are xerophytic type plants. The saying used so often “Water is life” applies equally to amenity landscapes as it does to human survival. Amenity landscapes very often require supplementary water application over and above normal rainfall (Stabler and Martin, 2004). Within the South African context where the average annual rainfall is only approximately 450 mm, compared to the global average of 860 mm (Winter, 2010). This becomes a pertinent issue, as the average South African amenity landscape would almost always require supplementary water application. To draw the linkage of the water situation to amenity landscapes, it is necessary to understand the extent of drought(s) and how the lack of water impacts amenity landscapes and ultimately the value of these landscapes to society.
There is a need within society to continually quantify goods, services or benefits. When considering the world of flora, amenity landscapes (mixture of turfgrass/lawns, annuals, perennials, shrubs and woody plant species) are measured against an unquantifiable yield, whereas agriculture is measured with a specific yield in mind. As a result, the concept of optimum growth and yield of agricultural crops is irrelevant for amenity landscapes (Allen, et al., 1998; Kjelgren, Rupp and Kilgren, 2000). Hence the conundrum of water use/requirements for amenity landscapes.
Droughts impact water availability
South Africa is periodically afflicted by severe and prolonged droughts, which are often terminated by severe floods (Earle, Goldin and Kgomotso, 2005). Examples of previous severe droughts occurred from 1925 to 1933, from 1944 to 1946, from 1950 to 1952, from 1962 to 1971 (The Department of Water Affairs, 1986), 1982 to 1995 (Backeberg and Viljoen, 2003), 2016 (Agri SA, 2016) and more recently 2017 (Masante, McCormick and Vogt, 2018).
Droughts imapct on available water as is indicated in recommendations from the OXFAM report on the current severe drought indicating that more focus be placed on water conservation and water demand management, that tighter restrictions be placed on water users, and that charges be imposed on higher use households (e.g. leisure uses, car washing, garden watering,etc.) (Hornby, et al., 2016). These pressures will place more and more constraints on water use for amenity landscapes, as users try to redistribute their available water for consumption between applications.
Sustainability of water systems
The continual and almost cyclical droughts point society to an ever increased need to use water more sustainably. Achieving the objectives of water efficiency, equity and sustainability are possibly the biggest problems for society (Armitage, et al., 2014). The transforming of cities to include sustainable urban water management concepts requires not only a paradigm shift for planners but also with end users alike. This amongst other factors involves creating landscapes that have an inherent ecological function linked to the inter-relationships within the environment (Armitage, et al., 2014). In Australia, in recent years actions aimed at sustainable water use, have been implemented to encourage water management plans across the country (Australian Government National Water Commission, 2011), namely:
- short-term restrictions focussed mainly on outdoor garden watering,
- medium-term water efficiency programs, influencing both indoor and outdoor structures and behavioural demand,
- long-term regulations, compelling new and existing households to meet significant demand-reduction targets.
Pares-Franzi, Sauri-Pujol and Domene (2006) state that the environmental performance of urban spaces could be improved significantly if practices of using high water demand species where changed to rather focus on utilising plants that require less water. This type of intervention should be applied to the South African context to assist with improving sustainable water use in urban areas, by business, industry, and particularly in amenity landscapes.
Traditional and technical water conservation practices improved over time
Many traditional and technical practices/interventions (e.g. mulching, water harvesting, water recycling and head to head spacing of sprinklers) are implemented within amenity landscapes to reduce supplementary water requirements. Some examples of these interventions being (Bartlett, 2006);
- In recent years the use of polymers and wetting agents has enabled water to remain longer within the root zone.
- The improved understanding of the chemistry of water and soils has allowed for the altering of pH levels with natural elements, which has improved water and nutrient uptake.
- Moreover, the ability to create a network of multiple amenity landscape sites using specific computer generated data, allows for accurate irrigation schedules by means of accurate programming.
- Irrigation technology (sprinkler check valves, droplet size control and flow sensors) has improved by allowing for greater control over water application rates, times and volumes.
- On-site weather stations linked to irrigation systems provide for real-time information on wind, humidity, heat and solar radiation, which can be used to influence water application periods and frequency to specific parts of the landscape based on need.
Improved cultural practices assists in providing a mechanism which allows for improved water use in amenity landscapes.
The value of amenity landscapes and plants
The benefits of well-maintained amenity landscapes are not widely understood, resulting in these landscapes being high on the priority list when imposing water conservation measures (International Turf Producers Federation (ITPF), n.d.). Without an agreed or perceived market value of an amenity landscape, the value of the water application on the amenity landscape cannot be measured. Unfortunately, most of the benefits (direct as well as indirect, physical and psychological) of the Green Industry are difficult to quantify financially, which results in them being seen as non-essential. Unseen benefits of the Green Industry/amenity landscapes include amongst others (Dwyer, Schroeder and Gobster, 1991; Moffat, and Schiller,1994; Holtzhausen, 2005; Fjeld, 2000; Aldous and Binkley, 2001; Ashwell and Hoffman, 2001; Frumkin, 2001; Akbari, 2002; Fang and Ling, 2003; Omasa, et al., 2003; Grobbelaar, 2005; Gies, 2006; Dixon and Wolf, 2007; Kollmuss, Polycarp and Zink, 2008):
- Improved aesthetics,
- Psychological well-being,
- Reduced sickness and improved health,
- Physical fitness, body health and stress relief,
- Carbon sinking/sequestration,
- Air conditioning and temperature control,
- Noise reduction barrier,
- Flood attenuation,
- Increased shading and associated cooling,
- Urban greening,
- Reducing and slowing down soil erosion,
- Reduction in loss of soil water content,
- Reduction of heat island effect, and
- Wastewater treatment.
Direct and indirect benefits of amenity landscapes are increased or decreased depending on the condition, management of and standard of these landscapes. This in turn is influenced by aspects such as, design, plant selection and placement, maintenance and water application.
Amenity landscape water use
Water use in an amenity landscape involves a wide range of environmental and site related matters (such as microclimate, solar radiation, wind, slope, soil factors shade, etc.). Each amenity landscape is unique, in its plant selection, design and location resulting in specific water requirements and should be treated as such.
Plants require sufficient water of adequate quality and at the right time and frequency within the root growth zone for them to grow (FAO, 2017; Whiting and Wilson, 2018). In an ideal situation, amenity landscapes should only be irrigated when rain is insufficient to support expected plant growth. Depending on site location, this irrigation can be permanent in more arid type areas or temporary in areas with high rainfall in the rainy season (Kjelgren, Rupp and Kilgren, 2000). However, in many situations watering systems are set to water at specific times and as a result water irrespectively of whether water is required by the landscape or not. There are specific periods and reasons why some landscapes legitimately require additional watering, examples being:
- Plants planted from bags need short term irrigation after planting until they have established new roots in the surrounding soil. Similarly, plant pots and planters require periodic irrigation/watering regardless of the climate (Kjelgren, Rupp and Kilgren, 2000).
- Plants planted in incorrect climate or hydrozones with insufficient rainfall/irrigation to sustain their growth (Randolph, 2005).
- The in-situ growth and establishment of annuals and grasses from seed, in an amenity landscape.
- Newly planted landscapes should be well watered for between 12 and 24 months to allow for settling in of plants (SAGIC, 2018).
Traditionally outdoor water use was calculated by taking the average winter consumption and subtracting that from the total water consumption for summer (Kjelgren, Rupp and Kilgren, 2000). This excluded actual rainfall. This approach assumed that no outdoor watering occurred in winter. It has more recently been considered to be incorrect, as outdoor watering does in fact occur in many amenity landscapes in winter ( American Water Works Association Research Foundation (AWWARF), 1999; Australian Government National Water Commission (ANWC), 2011. Devi (2009) indicates that the use of water for amenity landscapes, swimming pools and car washing, varies depending on the location of the landscape and the climate of the location (Devi, 2009). This is evident in Table 2.1 where water use in America and Australia for a large variety of locations, varies between 7% of total domestic water use to 75%, whilst for South Africa figures are quoted at between 30% and 73%. More detailed examples are available in Annexure 1.
CHAPTER 1 – INTRODUCTION
1.1. Rainfall, evaporation, weather and climate change
1.2. Water is limited and critical for future growth
1.3. Amenity landscapes linkage to water use
1.4. Justification for the research
1.5. Rationale for this research
1.6. Research design
1.7. Thesis structure
CHAPTER 2 – LITERATURE REVIEW
2.2. Impact of water use on amenity landscapes
2.3. Plant database, hydrozones and other plant water aspects associated to amenity landscape water use models
2.5. Site, management and environmental factors associated to amenity landscape water use models
2.6. Assessment of amenity landscape water use formulas/models
CHAPTER 3 – METHODOLOGY
3.1. Methodology used for the literature review, industry engagement, including climatic, plant and model data gathering as well as development and testing of the Amenity Landscape Water Use Model (ALWUMSA)
3.2. Climatic maps and figures that are associated with amenity landscape water use modelling
3.3. Plant data base and hydrozones associated to landscape water use models
3.4. Amenity Landscape Water Use Model (ALWUMSA)
3.5. Testing of ALWUMSA against sites, scenarios and other models
3.6. Specific methodology relating to Northern and Southern hemisphere referencing as well as referencing method used
CHAPTER 4 – CLIMATE MAPS AND FIGURES ASSOCIATED WITH AMENITY LANDSCAPE WATER USE MODELLING
4.3. Discussion and conclusion
CHAPTER 5 – PLANT DATABASE AND HYDROZONES ASSOCIATED TO LANDSCAPE WATER USE MODELS
5.2. Plant database generation and refinement
5.4. Allocation of factors to hydrozones (e.g. Crop, species and plant factors)
CHAPTER 6 – AMENITY LANDSCAPE WATER USE MODEL SOUTH AFRICA
6.2. Modelling plant water use for amenity landscapes
6.3. Amenity Landscape Water Use Model South Africa (ALWUMSA)
6.4. ALWUMSA formula
6.5. Baseline testing of ALWUMSA to the actual site
6.6. Testing of ALWUMSA to other selected models
6.7. Testing of ALWUMSA to a range of scenarios based on site information
6.8. Comparison of ALWUMSA to on-site water use before and after water restrictions imposed
CHAPTER 7 – CONCLUSION AND RECOMMENDATIONS
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