8. Water conservation and water saving practices and management
8.5. Water conservation and savings in landscape and recreational uses
Landscape and recreational water uses include a variety of outdoor and indoor uses and can be managed by municipal, governmental or private institutions, but all have in common the fact they are for public use. Landscape irrigation represents more than 20 % of irrigation water use in the United States, from which about 10 % are for irrigation of gulf courses (Shank, 1996).
Water conservation and water saving issues are summarised in Table 8.7.
(a) Gardens and lawns: Water savings in garden and lawn irrigation can be achieved through several practices:
1. Adopting appropriate garden watering practices, particularly avoiding excess water application. The amount of irrigation water that should be applied varies with the climate. Because most garden plants are shallow rooted, the recommended depth of soil moistening during the watering period is only 15 cm. Irrigation should stop when ponding or runoff occurs, which points out that water applied is in excess of infiltration.
2. Using irrigation equipment that helps reduce irrigation water use, preferably micro-irrigation: localised drip irrigation for trees, shrubs and flowers in a row;
microsprayers for lawns and flowers in a wider space; bubblers or drippers for small basins. Drip lines may have drippers at different distances according to plant spacing, and may be laid or buried in a curvilinear orientation as the plants. Microsprayers may have a variety of spray heads to irrigate in circles, half circles and corners with different angles; they also have a variety of discharge, wetted diameters, wetted patterns and drop sizes, including mist, which can be adapted to every kind of garden plants.
3. Using simple information for scheduling irrigation: plant appearance, soil touch and feel, broadcast information on evapotranspiration, or instruments for indicating the
soil water depletion in the upper 15 cm soil layer. These instruments, although not very precise, are helpful to city customers, and are easily available in garden shops.
TABLE 8.7. Issues in water conservation and saving in recreational water uses
Water use Issues Applicability
Gardens and lawns Selection of ornamental plants less sensitive to water stress
Adopt water reuse
Adopt well designed and automated drip and micro-spray irrigation systems
Establish irrigation management strategies to cope with increased levels of water scarcity
Irrigate by night
Use soil mulch and weed control
Requires technological support and training of personnel to be effective
Pools and ponds Use water purification tools when not used to support life, such as fish
When having fish, use a technique similar to fish ponds, or flowing water for other uses, e.g. as irrigation tanks
Requires planning and technical support to personnel
Golf courses Adopt an irrigation design oriented for easy management under scarcity
Reuse treated wastewater for irrigation
Establish irrigation management strategies to cope with increased levels of water scarcity
Requires new approaches in design and management, and training of personnel
Parks and Lakes Enforce water quality policies
Adopt integrated resource management Needs involvement of public authorities
Sport areas Sprinkler irrigation of green areas with high uniformity
Adopt precise irrigation
Requires technical support
Swimming-pools Use purification tools and chemicals
Enforce health prevention measures Easy Indoor facilities Adopt controlled flush toilets
Adopt limited flow showers
Use time controlled hand-wash taps
Use controlled discharge kitchen taps
Care for leak detection and repair
For most of the issues, they follow common sense practices
General issues Publicise water saving measures
Advertise to make water users aware
Educate children and youth
Favours public behaviour
4. When strong restrictions on water supply are enforced for outdoor irrigation, the following strategies may be adopted, in the order of increasingly stringent restrictions:
to decrease the frequency of irrigation but apply the same amount of water at each irrigation; to decrease both the frequency and the irrigation volumes;
to abandon the irrigation of annual plants, so maintaining the irrigation of the perennials only;
to abandon the irrigation of lawns but watering trees and shrubs to keep them alive when they are difficult to replace.
5. Adopting automation when micro-irrigation or sprinkling is used. Automation makes it easier to adopt the water saving irrigation practices referred above, and allows for irrigating by night, when wind drift and evaporation losses are minimal, and water demand to the supply system is also lesser, so minimising impacts on the functioning
of the supply system. When automation is not available, the best time to irrigate is between 4 and 8 a.m. or, when this schedule may be inconvenient, an alternative is between 8 p.m. and midnight.
6. Using mulch for soil water conservation, particularly to control evaporation. Various types of mulch can be used in gardens: organic mulch made from wood residuals, stone mulch, namely of gravel type or riverbed stones, coarse sand, and straw mulch.
Other products for mulch may be available in gardening shops, or be prepared in public gardens with available materials.
7. Adopting weed control is also important because weeds compete with garden plants for water and nutrients.
8. Selecting garden plants native to the region or well adapted to the prevailing environmental conditions, including low water demand, is a potential condition for successfully coping with water scarcity. On the contrary, choosing ornamental shrubs and trees from temperate and humid climates creates additional water requirements and great management difficulties since these plants are very sensitive to water stress. An alternative to native plants, or in combination with them, are the ornamental xerophytes, such as cactus, which are extremely efficient in water use.
When ornamental shrubs and trees from temperate and humid climates are selected for gardens in water scarce areas, it is advisable to consider the use of water of inferior quality for irrigation, including treated wastewater. Microirrigation systems (drippers and bubblers but not microsprayers and microsprinklers) are the most adequate when reused wastewater is applied. Filtering should then be carefully designed.
9. Careful layout and pipe network design as well as appropriate selection of emitters and filters are required. A good design and good quality of materials avoid uneven pressure distribution, non-uniform discharges, and frequent system failures. It makes automation easy and favours the implementation of water saving strategies. Poor design and low quality equipment cause irrigation management to be difficult, and waste of water and plant stress to occur more easily.
(b) Pools and ponds: two situations can be considered:
1. When pools do not support life, i.e. no fish are present, the best water saving practice is to avoid the need for frequent replacement of the water. This can be achieved by applying a treatment technique for water clarification to combat water eutrophisation.
2. When pools and ponds support life, such clarification treatment is not viable because of chemicals affect the fish. If a prime objective is to have fish, then technologies similar to those for fish-ponds may be adapted. Life and clear water may be achieved if pools and ponds are used as irrigation tanks with permanent flowing water.
However, it may be required to reduce the stored volumes in proportion to the volumes used in irrigation to avoid eutrophisation, i.e. to keep the water moving. To treat the water against eutrophisation may be expensive and not justified when heavy restrictions are applied. Ponds with standing water have to be avoided for environmental and heath protection since they constitute an attractive base location for water borne diseases.
(c) Golf courses: large volumes of water are required to fully irrigate golf courses. In general good design and equipment are used since this is a high-income generation activity. Water savings can be attained when:
1. Sprinkler or, less often, micro-sprinkler irrigation systems are utilised. Irrigation is better performed at night, so evaporation and wind drift losses are minimised.
Different requirements in the various parts of the area may be satisfied when the system is designed accordingly. Therefore the system should be designed for different irrigation management in each of the grassed areas near the holes, in the area of approach, on the fairways and in the surrounding areas.
2. Grass may be selected, at least for certain areas in the green, among species that have less water requirements and are less sensitive to water stress.
3. Under-irrigation problems may be avoided when treated wastewater is used.
Favourable conditions for its use exist because these irrigation systems are automated, night irrigation is the rule, and the direct contact of humans with the irrigation water is minimal. However, monitoring is advisable to prevent any negative health impacts. Filters are then required for safe operation of the irrigation system depending on the characteristics of the water (for wastewater reuse, see sub-heading 7.2).
4. When limited water is available, the following deficit irrigation strategies may be adopted as supply restrictions increase:
abandon irrigation outside of the fairway areas,
reduce irrigation in the fairway area keeping the greens fully irrigated ,
under-irrigate all areas except the green near the holes,
under-irrigate to just keep the grass alive. To play under these conditions is more difficult but is more challenging!
(c) Parks and Lakes. Water uses concern the maintenance of ponds, the irrigation of gardens and lawns, and the irrigation of plant nurseries and greenhouses. Issues relative to the first two have been described above. For the latter, approaches outlined below for irrigated agriculture may be adopted. Lakes are usually at low levels or dry when high water scarcity occurs and, often, recreational lakes are exploited for adding to the limited available resource. The main issues concern water quality preservation since the concentration of pollutants increase when flows supplying those lakes decrease.
Therefore, the focus of attention should be on the enforcement of water quality policies in the upstream areas, aiming at limiting point-source pollution and at expanding the treatment of effluents to be returned to nature.
(d) Sport areas and swimming pools. They consist of indoor facilities, which are dealt under 8.5 (f), below, and outdoor support areas. In the latter, water consumption mainly concerns the irrigation of green areas, washing of stadium seats, floors and parking lots:
1. Irrigation of green areas: Sprinkler irrigation with portable pipe laterals or hand pull hose systems are practised. To keep fields in good conditions for sports practice, grass water stress is not allowed. To avoid health hazards, using treated wastewater is not viable. Then water saving practices concern:
adoption of an optimal irrigation schedule, which can easily be performed if information on evapotranspiration is made available, particularly through the mass media,
use of a well designed system having high uniformity of application, and adopting proper equipment and maintenance (e.g. Smith, 2001),
irrigating at the early hours of the day, when wind and evaporation are small, and pressure available from the supply system is higher and has reduced time variability.
2. Washing: Saving water in cleaning activities is mainly possible by replacing washing by cleaning dry, using cleaning machines in large areas, and avoiding hose washing, which is always wasteful of water.
3. Swimming-pools: water savings consist of:
using purification equipment and chemicals that avoid frequent refills of the pools,
adopting health preventive measures for users,
caring about leak detection and repair.
(e) Indoor facilities: water uses in indoor public facilities mainly concern the toilet area in public buildings and in support of outdoor activities, the shower area in sports facilities, food areas in support of recreational activities, and washing of floors and special rooms.
Corresponding issues for water saving are common to those analysed for domestic uses, which are analysed under sub-heading 8.4.1. Essentially, they consist in:
1. Toilets: recommendations given under 8.4.1.(a) apply, particularly toilets with double flushing and toilets with flushing controlled by sensors.
2. Showers: controlled discharges as suggested under 8.4.1. (b).
3. Basin taps in bath rooms: among recommendations under 8.4.1 (c), those for adopting valves with sensors that activate the water flow only when the hands are placed beneath the taps, and valves for limited flow time are most appropriate.
4. Basin taps in kitchens: among items referred under 8.4.1. (c), recommendations mainly concern flow reduction devices, easy manoeuvring taps, and care for keeping taps closed when not being required.
5. Dish washers and clothes washers: recommendations under 8.4.1. (d) and (e) generally apply.
6. Control of indoor leaks: This includes
caring for detection and repair of leaks in pipes, plumbing fixtures and toilets,
using leak-proof fittings and other materials with specifications which correspond to pressures to be used as well as to the temperature of the water,
adopting good construction techniques and materials, as well as testing at the installation phase.