42 LANDSCAPING

42.1        GENERAL....................................................................................................................42-1

42.1.1     Use and Function...........................................................................................42-1

42.1.2     Plant Characteristics.......................................................................................42-1

42.2        SPECIFIC LANDSCAPING CRITERIA...............................................................................42-1

42.2.1     Ponds and Constructed Wetlands.....................................................................42-1

42.2.2     Infiltration and Filter System...........................................................................42-8

42.2.3     Vegetated Infiltration Basin (Bioretention)........................................................42-8

42.2.4    Vegetated Floodway/Open Channel..................................................................42-11

42.2.5     Natural Waterways/River Corridor....................................................................42-11

42.2.6    Vegetated Filter Areas and Swale.....................................................................42-12

42.3        OTHER CONSIDERATIONS IN STORMWATER LANDSCAPING..........................................42-12

42.3.1    Topsoil..........................................................................................................42-12

42.3.2     Wild Collection...............................................................................................42-15

42.3.3     Habitat Creation.............................................................................................42-15

42.4        GENERAL PLANTING/CONSTRUCTION METHOD.............................................................42-17

42.5        POST PLANTING MANAGEMENT...................................................................................42-17

APPENDIX 42.A     LANDSCAPING PLANTS FOR VARIOUS WATER-RIPARIAN ZONES.......................42-18

42.A.1     Recommended Plants Species for Zone 1 (Deep Water Pool)..............................42-20

42.A.2     Recommended Plants Species for Zone 2 (The Shallow Water Bench).................42-21

42.A.3     Recommended Plants Species for Zone 3 (Shoreline Fringe)...............................42-22

42.A.4     Recommended Plants Species for Zone 4 (Riparian Fringe)................................42-23

42.A.5     Recommended Plants Species for Zone 5 (Floodplain Terrace)...........................42-24

42.A.6     Recommended Plants Species for Zone 6 (Upland Slopes)..................................42-25

42.A.7     Recommended Grass Species for Vegetated Filter Strips and Swales...................42-26

42.A.8     Recommended Plants Species for River Margin.................................................42-27

42.A.9     Recommended Plants Species for Stream Lower Bank.......................................42-28

42.A.10   Recommended Plants Species for Stream Upper Bank.......................................42-29

42.A.11   Recommended Plants Species for Stream Terrace Face......................................42-30

42.A.12   Recommended Plants Species for Stream Upper Terrace....................................42-31

42.A. 13   Recommended Plants Species for Ecological Plants/Fruits Bearing Trees..............42-32

42.A. 14   Recommended Plants Species for Wild Life Attraction/Breeding Habitat Creation.. 42-33

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42.1 GENERAL

This chapter is prepared based on references from various materials sourced locally as well as from overseas namely Maryland Stormwater Design Guidelines (Schueler, 1998) and Christchurch City Council (1996). They are used in providing guidelines and criteria in landscaping the stormwater components including the ponds, retention, conveyance and stream system.

Various aspects of plants in term of their functions are evaluated and considered to assist and best serve the stormwater BMPs particularly in the context of the urban setting to promote a pleasant and healthier living environment

42.1.1   Use and Function

In selecting plants, consider their desired function in the landscape. Is the plant needed as ground cover, soil stabiliser, or a source of shade? Will the plant be placed to frame view, create focus, or provide an accent. Does the location require will provide seasonal interest to neighbouring properties? Does the adjacent use provide conflict or potential problems and require a barrier. Screen or buffer?. Nearly every plant and plant location should be provided to serve some function in addition to any appeal.

42.1.2   Plant Characteristics

Certain plant characteristics are so obvious, they may actually overlook the plant selection in term of

1.     Size

2.     Shape

For example, tree limbs, after several years, can grow into power lines. A wide growing shrub may block an important line of sight to oncoming vehicular traffic. A small tree, when full grown, could block the view from a second story window. Consider how these characteristics can work for you or against you, today and in the future.

Other plant characteristics must be considered to determine how the plant provides interest and whether the plant will fit with the landscape today and through the years to come. Some of these characteristics are

1.     Colour

2.    Texture

3.     Interest, i.e.-Flowers, Fruit, Leaves, Stems/Bark

4.     Growth rate

In urban or suburban settings, the landscape treatment of the stormwater facility shall be appealing and interesting. Careful attention to the design and planting of a facility can result in greater public acceptance and increased property value.

42.2 SPECIFIC LANDSCAPING CRITERIA

Stormwater management affects both the built and natural environment by either enhancing or adversely affects the community's quality of life. This includes reducing the flood risk, improving water quality and providing amenities and recreational opportunities. As such managing the urban water runoff should be a fundamental component of the urban planning process. Unfortunately the importance of focusing the stormwater runoff management has not been recognised in the past.

42.2.1 Ponds and Constructed Wetlands

Stormwater BMPs provision of constructed wetlands will be designed, built and operated to emulate the functions of natural wetlands for human needs serving important functions mainly purification, hydrologic buffering and other ecological functions. Constructed wetlands used for stormwater are comparatively simple than the conventional treatment plant and commonly created to emulate the marshland or wetlands whereby plants form the important elements that serve its ecological function. As such proper landscaping of the constructed wetlands will determine the effectiveness of stormwater best management practices (BMPs) in particular toward creating a healthier and sustainable urban development.

(a) Functions

Constructed wetlands intend to imitate the function of natural wetland which can effectively remove or convert large quantities of pollutants from point sources and non-point sources including organic matter, suspended solids, metals and excess nutrients.          Natural filtration,

sedimentation and other processes of the wetland plants through absorption and assimilation help remove nutrients for biomass production. Nevertheless, developing constructed wetlands as stormwater BMP'S with ecological aspect attempt to acheve the following objectives:

1.     Improving water quality;

2.     Economical or inexpensive to build;

3.     Largely self maintaining, requiring little or no operation or maintenance and time or expense;

4.     Manageable by operators with very limited training;

5.     Capable of providing aesthetic and passive recreation;

6.     Creating habitat for native fauna; and

7.     Community's educational benefits.

In fact stormwater wetlands that are carefully integrated into a site plan rely on gravity flow, require little upkeep, have no moving parts, are dependable, predictable, self regulating, and aesthetically pleasing.

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(b)      Components

The principal layout for a constructed stormwater wetland consist of a permanent pond with at least one quarter of the pond's surface area should be planned as open water ranging from 1.0 - 3.0 metre. The remainder of the pond should be shallow at a depth of 0.2 - 0.3 metre. Reference should also be made to Section 35.8 in Chapter 35. Approximately 30 percent of the shallow water should be planted with wetland species (macrophyte) in clusters around the basin perimeter to improve the water quality. A forebay, taking the form of a depression 1 metre deep, should be located at the point where stormwater flows into pond to capture large pieces of sediments. Mosquitoes usually are not a problem when all portions of the basins are connected to open water so that larvae can be controlled by natural predators.

(c)      Plant Selection

Basically constructed wetlands should vegetation with the following attributes:

consists of

1.     Adaptation to the local climate and soils (native species).

2.    Tolerance to pollutants in the water or wastewater.

3.     High biomass production.

4.     Perennial species.

5.     Rapid growth but to avoid usage of noxious species namely Eichornia crassipes (keladi bunting), Limnocharis flava (yellow bar head), Salvinia molesta (lukut lukut), Mimosa pigra (kemang gajah), etc.

6.     Non-weedy, aesthetic habit.

7.     Values for wildlife habitat.

8.     Broadest possible feasible mixture of plant species to maximise plant diversity and enhance stability of the constructed wetland.

Aquatic vegetation and riparian trees have important role on the ecology of the ponds. Certain plants improve the water quality by absorbing pollutants, using nutrients, and providing suitable habitat for micro-organism that help cleanse the water. As plants have different tolerance to inundation, the wetland basin is categorised into six zones, which dictate the particular plants that can survive within each zone. Planting within the stormwater or constructed wetlands requires determining the hydrologic zones or water depth in the new system facilities. Hydrologic zones refer to the degree to which an area is inundated by water. Planting zones are categorised based on the 6 different zones, which are listed in the Table 42.1 below and shown in Figure 42.1.

Table 42.1 Hydrologic Zones

BWL = below water level

AWL = above water level

0.3-1.2 m AWL 0-0.3 m AWL' 0-0.3 m Depth 0.3-1.8 m Depth

Upland Slopes ui£ 2!. ■*■ 5' (Zone 6) " ^{3 WI}S

Figure 42.1 Longitudinal Section of Typical Wetland

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Zone 1: Deep-water Pool (0.3 -1.8 metre)

Should contain submerged aquatic plants such as Nymphaea sp. (Water lily) and Nelumbo nucifera (Telipok) that help to increase diversity of the pond (see Table 42.2 and Appendix 42.A.1). Certain spectacular varieties of water lilies have great aesthetic appeal that can be confined to designated locations by planting in wooden crates. The availability of plants that can survive in this zone is limited and it is also feared that plants could clog the stormwater facility outlet structure. If submerged plant material becomes more commercially and clogging concern are addressed, this area can be planted. The function of planting is to reduce re-sedimentation and improve oxidation while creating greater aquatic habitat. Criteria for selecting the plants are as follows:

1.     Able to withstand constant inundation of water up to 0.3 metre.

2.     May be submerged partially or entirely.

3.     Should be able to enhance pollutant uptake.

4.     May provide food and cover for waterfowl, desirable insects (dragonfly), and other aquatic life.

Zone 2: Shallow Water Bench

located at the edge of the pond or on low mounds of earth located below the surface of the water within the pond. When planted, Zone 2 can be an important habitat for many aquatic and non-aquatic animals creating a diverse food chain. This food chain includes predators, allowing a natural regulation of mosquito populations, thereby reducing the need for insecticide application.

Criteria for the suitable plants are as follows:

1.     Should be able to withstand constant inundation of water to depths between 0.1 metre to 0.3 metre.

2.     Will be partially submerged.

3.     Should be able to enhance pollutant uptake.

4.     May provide food and cover for waterfowl, desirable insects and other aquatic.

Plants will stabilise the bottom of the pond as well as the edge of the pond absorbing wave impacts and reducing erosion, when water level fluctuates. In addition to slowing water velocities and increasing sediment deposition rates, plants can also reduce re-suspension of sediments caused by wind (Figure 42.2). Plants can also soften the engineered contour of the pond and can conceal drawdowns during dry weather.

Area inundated to a depth of 0.1 to 0.3 metre is a primary area for the emergent plants like Monocharia hastata (keladi agas) to grow (see Table 42.3). This area may be

Table 42.2 Recommendd Plant Species for Zone 1 (Deep -water pool)

P = Pollution control E = Ecological

B = Bank/slope protection A = Aesthetic

I = Indigenous

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Inflow

High Toxicant Load

High Inflow Velocity

Toxicants can be Stored in Sediments (a) Toxicant Removal/Retention

Sediment Settles out as Flow Rate Decrease

(a) Sediment Removal/Retention

Low Toxicant Load

Sediment-free Water

Inflow

Nutrient-rich Water

Nutrients can be Stored in Sediments (c) Nutrient Removal/Retention

Outflow

Nutrient-free Water

Figure 42.2 Use of Wetland Plant for Removal/Retention of Toxicants, Sediments and Nutrients

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Table 42.3 Recommended Plant Species for Zone 2 (Shallow water bench)

P = Pollution control E = Ecological

B = Bank/slope protection A = Aesthetic

I = Indigenous

Zone 3: Shoreline Fringe

Encompass the shoreline that extends vertically about 0.3 metre in elevation from the normal pool. The area includes a safety bench of a pond, and may also be periodically inundated if storm events are subject to extended detention. This zone occurs in a wet pond or shallow marsh and can be the most difficult to establish since plants must be able to withstand inundation of water during storms, when wind might blow water into the area. In order to stabilise the soil in this zone, Zone 3 must have a vigorous cover.

1.     Plants should stabilise the shoreline to minimise erosion caused by wave and wind action or water fluctuation.

2.     Plant material must be able withstand to occasional inundation of water. Plants will be partially submerged at this time.

3.     Planting rows should generally traverse the narrow axis of the pond rather than the long axis.

4.     Plant material should, whenever possible, shade the shoreline to reduce the water temperature.

5.     Plants should enhance pollutant uptake.

6.     Plants may provide food and cover for waterfowl, songbirds, and wildlife. Large plants can also be selected and located to control overpopulation of waterfowl.

7.     Plants should be located to reduce human access where there are potential hazards, but should not block the maintenance access.

10.

Plants should have very low maintenance requirements, because they may be difficult or impossible to reach.

Plants should be resistant to disease and other problems, which require chemical applications (since chemical application is not advised in stormwater ponds).

Native plants are preferred because they are low maintenance and disease resistant.

Many of emergent plants in Zone 2 also thrive in Zone 3 (Table 42.4). If shading is needed along the shoreline, tree species are also recommended.

Zone 4: Riparian Fringe (Periodically Inundated)

Zone 4 extends from 0.3 metre to 1.2 metre in elevation above the normal pool. Plants in this zone are subject to periodic inundation after storms, and may experience saturated or partly saturated soil (Table 42.5).

Plants must be able to withstand periodic inundation of water after storms, as well as occasional drought.

Plants should stabilise the ground from erosion caused by run-off.

Plants should have the low flow channel to reduce pool warming whenever possible.

Plants should enhance pollutant uptake.

3.

4.

5.

Plant material should have very low maintenance, since they may be difficult or impossible to access.

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6. Plants may provide food and cover for waterfowl, 7. Plants should be located to reduce pedestrian access songbirds and wildlife. Plants may also be selected                to the deeper pools.

and located to control overpopulation of waterfowl.               _{8 Native p}|_{ants are pre}ferred because they are low

maintenance and disease resistant.

Table 42.4 Recommended Plant Species for Zone 3 (Shoreline Fringe)

P = Pollution control               B = Bank/slope protection

E = Ecological                         A = Aesthetic                                    I = Indigenous

Table 42.5 Recommended Plant Species for Zone 4 (Riparian Fringe)

P = Pollution control                           B = Bank/slope protection

E = Ecological                                     A = Aesthetic                                    I = Indigenous

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Zone 5: Floodplain Terrace (Infrequently Inundated)

Zone 5 is periodically inundated by floodwaters that quickly recede in a day or less. Operationally, Zone 5 extends from maximum two year up to the 10 or 100 year maximum water surface elevation. This zone may contain footpaths, cycle paths and maintenance access roads. Key landscaping objectives for Zone 5 are to stabilise the steep slope characteristics of this zone and establish low maintenance natural vegetation.

1.     Plant material should be able to withstand occasional but brief inundation during storms (Table 42.6).

2.     Plants should stabilise the basin slopes from erosion.

3.     Ground cover should be very low maintenance, since they may be difficult to access on steep slopes or if frequency of mowing is limited. A dense tree cover may help reduce maintenance and discourage resident geese.

4.     Plants may provide food and cover for waterfowl, songbirds and wildlife.

5.     Placement of plant material in Zone 5 is often critical, as it often creates a visual focal point and provides structure and shade for a greater variety of plants.

Zone 6: Upland Slopes (Seldom or Never Inundated)

1.     Plant selection should be made based on soil condition, light and function within the landscape because little or no water inundation will occur.

2.     Ground covers should require infrequent mowing to reduce the cost maintaining this landscape.

3.     Placement of plants in Zone 6 is important since they are often used to create visual focal point, frame a desirable view, screen detrimental views, serve as a buffer, or provide shade to allow a greater variety of plant materials. Particular attention should be paid to colour and texture of these plantings (Table 42.7).

Most wetland plants are very adaptable and quickly become established in new environment if conditions are available. If substantial plant loss occur, poor planting techniques, inappropriate water levels, or inadequate nutrient are more likely to be the cause than poor planting stock.

Emergent species (shallow to mid depth zones) should be planted in saturated but not flooded soils and allowed to grow stems with leaves that project above planned flooding levels the first year. After stem reach 5-10 cm water level can be raised 2 to 3 cm above the substrate and proportionately increased as plant height increases until desired elevation are reached.

The last zone extends above the maximum 100-year water surface elevation, and often includes the outer buffer of a pond or wetland. Care should be taken to locate plants so they will not overgrow these routes or create hiding places that might make the area unsafe.

Maintaining stable water levels and keeping the plant continuously submerged is critical for these species.

Table 42.6 Recommended Plant Species for Zone 5 (Floodplain Terrace)

P = Pollution control E = Ecological

B = Bank/slope protection A = Aesthetic

I = Indigenous

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Table 42.7 Recommended Plant Species for Zone 6 (Upland slopes)

P = Pollution control E = Ecological

B = Bank/slope protection

A = Aesthetic                      I = Indigenous

42.2.2 Infiltration and Filter System

Combined infiltration and filter systems either take advantage of existing permeable soils or create a permeable medium such as sand for ground water recharge and stormwater quality control. In some instances where permeability is great, these facilities are used for quality control as well. The most common systems include infiltration trenches infiltration basins, sand filters and organic filters. Suitable plant species for these systems are given in Table 42.8.

When properly planted vegetation will thrive and enhance the functioning of these systems. For example, pre-treatment, buffer will trap sediment, to which phosphorus and metals are often adsorbed. Vegetation planted in the facility will aid in nutrient uptake and water storage. Additionally, plant roots will provide arteries for stormwater to permeate soil for ground water recharge. Finally, successful plantings provide aesthetic value and wildlife habitat making these facilities more desirable to the public.

They, however, are subjected to the following design constraints:

1.     Planting a vegetated filter strip of at least 5.5 metre width will cause sediments to settle out before reaching the facility, thereby reducing the possibility of clogging.

2.     Determine areas that will be saturated with water and water table depth so that appropriate plants may be selected (hydrology will be similar to bio-retention facilities)._____________________________________

3.     Plants known to send down deep taproots should be avoided in system where filter fabric is used as part of facility design.

4.     Test soil condition to determine if soil amendments are necessary.

5.     Plants shall be located so that access is possible for structure maintenance.

6.     Stabilise heavy flow areas with erosion control mats or sod.

7.     Temporarily divert flows from seeded areas until vegetation is established.

42.2.3 Vegetated Infiltration Basin (Bioretentio|i

(a) Soil Bed Characteristic

Soil bed characteristics for the vegetated infiltration basin facility are perhaps as important as the facility, location, size, and treatment volume. The soil must be permeable enough to allow runoff to filter through the media, while having characteristics suitable to promote and sustain a robust vegetative cover crop. In addition, much of the nutrient pollutant uptake (nitrogen and phosphorus) is accomplished through absorption and microbial activity within the soil profile. Therefore, the soils must balance soil chemistry and physical properties to support biotic communities above and below ground.

Because of the biological action, these facilities are also called "bioretention" facilities.

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(b)     Planting Guidance

Plant material selection should be based on the goal of simulating a terrestrial forested community of native species. Bioretention simulates an upland-species ecosystem. The community should be dominated by trees, but have a distinct community of understorey trees, shrubs and herbaceous materials (Table 42.9). By creating a diverse, dense plant cover, a bioretention facility will be able to treat stormwater runoff and withstand urban stresses from insects, disease, drought, and wind exposure.

The proper selection and installation of plant materials is key to a successful system. There are essentially three zones within the bioretention facility (Figure 42.3). The lowest elevation supports plant species adapted to standing and fluctuating water levels. This section can also be considered as swale. The landscape treatment for swale shall also serve as dry-bed stream with some shrubberries and boulders that will hold off water and trap floating debris during storm runoff (refer to Figure 42.4). Ornamental planting is also to be provided within the swale serving as an open space for recreation.

The middle elevation supports plant that like drier soil conditions, but can still tolerate occasional inundation by water. The outer edge is the highest elevation and generally supports plants adapted to drier conditions. The layout of plant material should be flexible, but should follow the general principle described below. The objective is to have a system that resembles a random and natural plant layout, while maintaining optimal conditions for plant establishment and growth.

(c)      Planting Plan Design Consideration

1.     Native plant species should be specified over exotic or foreign species.

2.     Appropriate vegetation should be selected based on the zone of hydraulic tolerance.

3. 4.

5.

Species layout should generally be random and natural.

A canopy should be established with an understorey of shrubs and herbaceous materials.

6.     Woody vegetation should not be specified in the vicinity of inflow location.

7.     Trees should be planted primarily along the perimeter of the bioretention area.

8.     Urban stressors (e.g. wind, sun, exposure, insect and disease).

9.     Infestation and drought should be considered when laying out the planting plan.

10.   Noxious weeds should not be specified.

11.   Aesthetics and visual characteristics should be a prime consideration.

12.  Traffic and safety issues must be considered.

13.   Existing and proposed utilities must be identified and considered.

Table 42.8 Recommended Shrubs Species for Basin

Middle Zone

Highest Zone

Lowest Zone

Species Tolerant to Fluctuating Water Level

Figure 42.3 Planting Zones for Bioretention Facilities

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Table 42.9 Suggested Plant Species for Bioretention Areas

-

Figure 42.4 Typical Section and Images of Landscape Swale within Recreation Area

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42.2.4 Vegetated Floodway/Open Channel

Vegetated waterways and open channel serve as an alternative to hard engineering drainage systems. However, they are not suitable for areas subject to regular inundation for long periods.The aim is to prevent erosion and improve water quality by allowing sediments to settle out before it flows into a permanent stream. Flows are reduced by roughness of grasses and water quality is further improved. These grasses are sod farming and withstand frequent inundation, and are thus ideal for the grass channel environment (Table 42.10).

Grassed floodways shall be designed in accordance with Chapter 28, Engineered Waterways.

The planting criteria for vegetated floodway and open channel are as follows:

1.     Ground cover should be tolerant to frequent inundation and erosion. Where possible one or more of the grasses should be in the seed mixes.

2.     Grass should be able to survive flood, drought, windstorm, grazing animals and other forces of nature except freezing.

3.     Has deep penetration root system, which can grow up to 3 metres in length. Long roots are very useful in improving stability of earth slopes as they provide reinforcement by holding the soil particles together and more importantly, remove subsoil mixture, which is detrimental to slope stability (Table 42.11).

4.     Do not compete seriously with neighbouring crop plants for moisture or nutrientsin soil.

5.     Cheap and easy to establish and maintain.

6.     Able to survive on many soil type almost regardless of fertility, alkalinity or salinity.

Table 42.10 Recommended Ground Cover Species for Swale/Open Channels and Basins

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42.2.5 Natural Waterways/River Corridor

Natural waterways with vegetated corridor play significant role in the drainage pattern that need to be protected and retained. Riverside or riparian vegetation helps protect the riverbank, provide breeding ground for aquatic life, temporarily holding overflow as well as trap sediments and some pollutants (refer Table 42.12 and 42.13).

Table 42.11 Recommended Main Ground Cover for Channel Slope Erosion/Treatment

A well-vegetated river helps store water along the corridor during the rainy season for slow release to the stream in drier season. Riparian vegetation also can slow flood velocities and help deposit and store sediment on the floodplains as opposed to the river channel downstream. During high flows the vegetation lies against the banks and protects them from accelerated erosion. As such planting for the river corridor in particular those that passes through the urban areas, which have been deprived, from vegetation is aimed toward restoring the river environment. Identification of suitable plant species will relate to the hydrologic zones or sections of the river as shown in Figure 42.5, which will help, revive or reinstate the natural condition and function of the river.

(a) Planting Guide

1.     Determine the profile of the river to identify the different characteristics or vegetation zones.

2.     Prepare a planting plan with composition of the plant species for the zones.

3.     Space plants according to the zone they belong in, and their mature size. You will need approximately one plant per square metre. Rushes small sedges and ferns can be planted up to three per square metre.

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4.     Select indigenous and hardy species that is adaptable and tolerant to site and soil conditions of flood plains and swamps.

5.     Order plants well in advance of planting. Select a nursery specialising in native plants.

6.     Plant appropriate species right down to the water's edge or margin.

7.     Prepare the site well in advance of planting.

8.     Remove invasive weeds such as Imprata cylindrica, Euchornia sp, Mimusa pudica and //7Gfca(Semalu).

9.     Clear all vegetation for about 1 metre diameter around each planting position.

10.   Set out plants in their correct zones, remembering to space out the plants according to how large they will grow.

11.   Before planting prune off entangled roots. Set the plants into a bed of soft, worked soil at the bottom of the hole, and repack crumbed soil around the root mass tightly to prevent air gaps.

12.   On wet sites, plant in a shallower hole so that the top of the root mass and associated soil is at ground level or even slightly mounded above it in permanently saturated condition.

13.   Ensure plants within the waterway are well planted and compacted around the base.

14.   For poor soil apply slow-release fertiliser to each plant and spread short-term fertiliser to the ground after planting and before mulching.

15.   Do not use mulch on wet sites or anywhere near the water flow, as mulch is likely to be washed away and may caused stream blockages.

(b) Selecting Plant Species

Due to the different conditions for establishment and growth of plants with soggy and inundated soil, riverside plants can be categorised into different vegetated zones.

These zones are based on slope condition and distance from the water edge. The species commonly found along the rivers are recommended for planting in restoring the river and its corridor into its natural forms and function creating the riverine landscape and parkland (Figure 42.6).

42.2.6 Vegetated Filter Areas and Swale

The purpose of filter area (or buffer strip) and swale are to intercept and cleanse runoff of pollutants through the natural process of filtration, biological uptake, and deposition of sediments, which occurs when the speed of runoff is slowed through the baffling effect of grasses and leaf litter.

Sediments and pollutants are partly removed by filtering, absorption and sedimentation. A constructed filter area offers an opportunity to use landscaping to enhance water resources. They are effective treatment to improve the quality of runoff water, self-adjusting and require only moderate amounts of maintenance.

42.3 OTHER CONSIDERATIONS IN STORMWATER LANDSCAPING

42.3.1 Topsoil

Topsoil are important in preserving and protecting the ground surface from erosion and able to absorb more efficiently water run-off. Removal of topsoil will deplete the land fertility for planting and also caused erosion and siltation of the waterways.

Topsoil shall be of granular structure, less than 27 percent clay, and 4 to 5 percent organic matter by weight. It shall be free from subsoil, roots, stones over 2.5 cm (1 inch) in diameter, herbicides, contaminants and other extraneous materials. Topsoil shall not be used in muddy condition and shall be furnished and hauled by the contractor to the site.

Upper Terrace

Figure 42.5 Typical Section of the Waterway

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Figure 42.6 Riverine Parkland

Table 42.12 Recommended Tree Species for River Corridor

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Whenever possible topsoil shall be spread to a depth of 15 cm (6 inches minimum) over the entire area to be planted. This provides organic matter and important nutrients for the plant material. The use of topsoil allows vegetation to become established faster and roots to penetrate deeper. This ensures quicker and more complete stabilisation, making it less likely that the plants will wash out during a heavy storm.

If topsoil has been stockpiled in deep mounds for a long period of time, it is necessary to test the soil for pH as well as microbial activity. If the microbial activity has been destroyed, it is necessary to inoculate the soil after application.

Areas that recently have been involved in construction can become compacted so that plant roots cannot penetrate the soil. Also seeds will lie on the surface of compacted soils are often washed away or eaten by birds. For planting success, soils should be loosened to a 17 cm depth. Hard soils may require discing to a deeper depth. The soil should be loosened regardless of the ground cover. This will improve seed contact with the soil, increase germination rates, and allow the roots to penetrate the soil. For areas to be sodded, discing is necessary so that the roots can penetrate the soil. Providing good growing conditions can prevent poor vegetated cover. This saves money because vegetation will not need to be planted.

Table 42.13 Recommended Palm Species for River Corridor

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Remember that newly installed plant material require water in order to recover from the shock of being transplanted. Be sure that some source of water is provided, especially during dry periods. This will reduce plant loss and provide new plant materials with a chance to establish root growth.

42.3.2 Wild Collection

Collection of wild plants are important as they are more adapted to the local environmental condition (Table 42.14). Wild plants have acclimated to local soils, typical hydrologic region and weather. Wild plants will initiate new growth more quickly and develop more robust growth habits at earlier stage than plants secured from nurseries as seed or potted plants.

Table 42.14 Recommended Wild Plant Species

42.3.3 Habitat Creation

Riparian vegetation performs a long list of important functions in the creation and maintenance of fish and wildlife habitat. Those functions can be summarised as follows:

1.     Riparian vegetation moderates water temperature, making the river habitable for fish and other aquatic life.

2.    Tree roots, shrub species and other growth bind the stream bank soil and provide resistance to erosive forces of the water (refer Table 42.15 and 42.16). This produces deeper channels with banks that are undercut but held together with exposed root systems. These undercut banks complete with overhang vegetation, provide important escape cover for fish.

3.     Most of the river/stream's biological energy and the base of the food chain for stream life come from the

leaves, fruits, seeds, cones and other parts of the plants.

4. Woody debris that falls into the river forms pools for fish, creates habitat by causing backwater pools, and provides storage areas for sediment that otherwise might be released into spawning areas.

Planting for ponds, wetlands and large waterways such as river shall incorporate opportunities for creation of wildlife habitat. The following are efforts to be taken for wildlife attraction:

1.     Understand the fundamental of ecological systems, relationship of the vegetation (flora) and fauna and their contribution to the pond and river environment.

2.     A diversed indigenous species are to be provided to ensure ample food supply through flowers, seeds and fruits to attract animals such as birds, squirrels, monkeys, bats and insects. Birds will feeds on frogs, fish and other forms of riverine life.

3.     Retain the existing valuable trees and other vegetation including herbaceous and ground cover.

4.     Breeding areas for fish and aquatic life are to be encouraged by improving the water quality and providing pools and undercuts for the rivers.

5.     Nesting materials such as moss, lichens, feathers, dried grasses and leaves shall be available to create ideal nesting area.

6.     Retain dead branches and logs in designated areas to create wildlife sanctuaries. Dead wood invites larvae, which are favoured by birds such as Woodpecker and Kingfisher, Little green heron (Pucung keladi), for food and nesting.

7.     Cutting and pruning shall be avoided during the breeding season between March and June. Pruning may expose the nest and hiding places as well as cause dehydration to the small animals.

8.     Climbers and epithytes are to be encouraged as they provide hiding place for insects and attract the foraging birds.

9.     Other wildlife that will be attracted to the river are Malayan box turtle, small clawed otter (Memerang kecil), Damselfly, Green pigeons, Barbets, Bittern and common myna (see Figure 42.7).

A vailability and Cost

Planting materials may be purchased from nurseries, dug from the wild, or grown by developers of a project. Often overlooked in plant selection is the availability from suppliers and the cost of the plant material. There are many plants listed in the landscape books that are not readily available from the local nurseries or market.

Without knowledge or what is available, time spent researching and finding the one plant that meet all the needs will be wasted. It may require long distance

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shipping, therefore making it more costly than the budget may allow. Generally, plants collected from the wild or similar wetlands in the vicinity will be more suitable than plants obtained from other sources of the plant in the landscape.

Table 42.15 Recommended Trees and Palm Species for Wildlife Habitat

Table 42.16 Recommended Shrub Species for Wildlife Habitat

In some cases it may be cost effective to investigate the nursery or supplier for the availability of wetland seed mixtures. Specification of the seed mix shall include wetland seed types and the relative proportion of each species. Some suppliers provide seed mixtures suitable for specific wetland, upland or riparian habitat conditions. This option may best be employed in small stormwater facilities such as pocket wetlands and open swales, or to complement planting in larger facilities.

Figure 42.7 Wildlife Attracted to the Water Environment

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42.4 GENERAL PLANTING/CONSTRUCTION METHOD

General planting methods apply to all elements discussed earlier that relate to the drainage functions and facilities such as ponds, wetlands, and swale.

1.    Trees or shrubs known to have long taproots should not be within the vicinity of earth dam, weir or subsurface drainage facilities.

2.    Trees and shrubs should be at least 4.5 metre away from the tow of the slope of a dam.

3.    Tree and shrubs should be at least 5 metre away from perforated pipes.

4.    Trees and shrubs should be at least 7.5 metre away from a riser structure.

5.     Provide 4.5 metre clearance from a non-clogging, low flow orifice.

6.     Herbaceous embankment plantings should be limited to 30 cm in height. This is to allow visibility for the inspector who is looking for burrowing rodents that may compromise the integrity of the embankment.

7.     Provide slope stabilisation methods for slopes steeper than 2:1 such as planted erosion control mats. Also, use seed mixes with quick germination rates in the area.

8.     Augment temporary seeding measures with container crowns or root mats of more permanent plant material.

9.     Use erosion control mats and fabrics in channels that are subject to frequent washouts.

10.   Stabilise all emergency spillways with plant material that can withstand strong flows.

11.   Root material shall be fibrous and substantial but lacking a taproot.

12.   Sod area channels that are not stabilised by erosion control mats.

13.   Divert flows temporarily from seeded areas until stabilised.

14.   Check water tolerances of existing plant materials prior to inundation of area.

15.   Stabilise aquatic and safety benches with emergent wetland plants and wet seed mixes.

16.   Do not block maintenance access to structures with trees or shrubs.

17.   Avoid plantings that will require routine or intensive chemical application (i.e. turf area).

18.   Have soil tested to determine if there is a need for amendments.

19.   Decrease the areas where turf is use. Use low maintenance ground cover to absorb run-off.

20.   Plant stream and water buffers with trees, shrubs, ornamental grasses and herbaceous materials where possible, to stabilise banks and provide shade.

21.   Maintain and frame desirable views. Be careful not to block views at entrances, exits, or difficult road curves. Screen unattractive views into the site. Aesthetics and visual characteristics should be a prime consideration.

22.   Use plants to prohibit pedestrian access to pools or slopes that may be unsafe.

23.  The designer should carefully consider the long-term vegetation management strategy for the BMP, keeping in mind the 'maintenance legacy for the future owners. Keep maintenance areas and access free of vegetation to allow vehicle clearance. Provide a planting surface that can withstand the compaction of vehicles using maintenance access roads. Make sure the facility maintenance agreement includes requirements to ensure vegetation cover in perpetuity.

24.   If a BMP is likely to receive excessive amounts of deicing salt, salt tolerant plants should be used.

25.   Provide signage for:

-   Stormwater management areas to help educate the

public.

-  Wildflower area, when possible to designate limits of

mowing.

26.   Avoid the overuse of any plants materials.

27.   Preserve existing natural vegetation when possible.

It is necessary to test the soil in which you are about to plant in order to determine the following:

•      pH, whether acid, neutral or alkaline.

•      Major soil nutrients; Nitrogen, Phosphorus, Potassium.

•      Minerals; such as chelated iron, lime.

Certain soil conditions, such as marine clays can present serious constraints to the growth of plant materials and may require the guidance of qualified professionals. When poor soils cannot be amended, seed mixes and plant material must be selected to establish ground cover as quickly as possible. Have soil samples analysed by experienced and qualified individuals, such as Agriculture Officer or Horticulturist.

42.5 POST PLANTING MANAGEMENT

Post planting management covers proper horticultural practices and maintenance to encourage the establishment of newly planted trees.

1.     Remember that newly installed plant material requires water in order to recover from the shock of being transplanted. Be sure that some source of water is provided, especially during dry periods. This will reduce plant loss and provide the new plant material with chance to establish root growth.

2.     Weeding around plants is essential to avoid competition and stress. This should be carried out

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after 2 months of planting or on a monthly basis as required.

3.     At the water margin, careful weed control is needed on an on-going basis until the area is self-maintaining, or until the plantings have overtopped the grass.

4.     Clearing weeds and pruning of trees after 4 and 12 months of planting.

5.     Pruning and trimming of unwanted shoots intended to encourage growth and development of quality plants in term of height and weeding after 6 months of planting.

6.     Be familiar with the common problem of post planting stress, which can aid in recognising them early and minimising the potential damage.

7.     Certain pest and physiological occur more frequently on stressed plants.

8.     Stress can be minimised and eliminated by judicious watering.

9.     Excess watering especially from irrigation systems causes anaerobic (low oxygen) soils, killing the small absorbing roots. With unhealthy roots the symptom can be similar to drought stress, with dull or drooping leaves and branch tips, scorched leaves margins, and eventual dieback.

10.   Regular check on the plant's health for several years, normally up to 4 years after establishment.

11.   Insect and disease control may periodically be required.

12.   Monitor the growth of the riverine vegetation and enjoy the sight as they thrive and attract wildlife and become self maintaining.

APPENDIX 42.A LANDSCAPING PLANTS FOR VARIOUS WATER-RIPARIAN ZONES

Appendix 42.A.1 Appendix 42.A.2 Appendix 42.A.3 Appendix 42.A.4 Appendix 42.A.5 Appendix 42.A.6 Appendix 42.A.7 Appendix 42.A.8 Appendix 42.A.9 Appendix 42.A.10 Appendix 42.A.11 Appendix 42.A.12 Appendix 42.A.13 Appendix 42.A.14

Recommended Plants Species for Zone 1 (Deep Water Pool)

Recommended Plants Species for Zone 2 (The Shallow Water Bench)

Recommended Plants Species for Zone 3 (Shoreline Fringe)

Recommended Plants Species for Zone 4 (Riparian Fringe, Periodically Inundated)

Recommended Plants Species for Zone 5 (Floodplain Terrace, Infrequently Inundated)

Recommended Plants Species for Zone 6 (Upland Slopes, Seldom or Never Inundated)

Recommended Grass Species for Vegetated Filter Strips and Swales

Recommended Plants Species for River Margin

Recommended Plants Species for Stream Lower Bank

Recommended Plants Species for Stream Upper Bank

Recommended Plants Species for Stream Terrace Face

Recommended Plants Species for Stream Upper Terrace

Recommended Plants Species for Ecological Plants/Fruits Bearing Trees

Recommended Plants Species for Wild Life Attraction/Breeding Habitat Creation

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42.A.1 Recommended Plants Species for Zone 1 (Deep Water Pool)

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42.A.2 Recommended Plants Species for Zone 2 (The Shallow Water Bench)

Caladium hortulanum 'hybnd'

Limnocharis flava

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42.A.3 Recommended Plants Species for Zone 3 (Shoreline Fringe)

Melaleuca leucadendron

Spondias pinnata

Salix babylonica

Accacia mangium

li-im-iifpus ahilis"''

Artocarpus altilis

Alstonia spathulata

H

Nepenthes sp.

Nepenthes sp.

Alocasia accorrhiza

Gesneriaceae sp.

Hydrocutycle asiatica

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42.A.4 Recommended Plants Species for Zone 4 (Riparian Fringe)

Ficus sp.

Dillenia sp.

Cratoxylon arborescens             Licuala spinosa

Clerodendron paniculatum

Bambusa sp.              Bambusa sp.'broadleaves' Johannesteijsmannia altifrons         Cassia alata

Nepholepis sp.

Mil'!!!;""""' w***««rv 11

Pandanus sp. 'green dwarf' Pandanus utilis

NeDholeDis exalata

•j* - .' -a *v.

Turnera almifolia

Ixora javanica

Mirabilis ialaoa

Asvstasia aanaetica

- >.. * ■■■-:-■. s-^5

Nephrolepis sp.

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42.A.5 Recommended Plants Species for Zone 5 (Floodplain Terrace)

Heliconia psitacorrum 'yellow'

Tacca chantrieri

Pandanus pigneus

Pandanus dubius

3»a

Melastoma malabathricum

Costus speciosus

Lantana camara

Mussaenda erythrophylla

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42.A.6 Recommended Plants Species for Zone 6 (Upland Slopes)

Eucalyptus deglupta         Dryobalanops aromatic         Milletia atropurpurea            Cinnamomum iners

Bauhinia blakeana

Canaga odorata

Croton sp.

Heliconia indica

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42.A.7 Recommended Grass Species for Vegetated Filter Strips and Swales

v*V

'±Jkk£j£z&

&P4 "."-'.-/- ■

STENOTAPHRUM SECUNDATUM (ST. AUGUSTINE)

warn

i siii^i

Axonopus compressus (Carpet Grass)

CYNODON DACTYLON (BERMODA

tez> sr

—    -57=*" uja PHSU*

- —. ■£££! >N IDA Tu*l

-itlifpfe....

rv\>V.

<.^K"?:

H^rMi:

Stenotaphrum secundatum variegatum

Zoysia sp. (Emerald)

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42.A.8 Recommended Plants Species for River Margin

Pandanus sp.

Zingiberaceace sp.

Phragmites karka

Cleome spinosa

V

s

loomoea aauatica

Ludwiaia adscendens

Hanguana malavana

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42.A.9 Recommended Plants Species for Stream Lower Bank

Piper sarmentesum           Hymenocallis specisa

Nephrolepis sp.

Quisqalis indica

Arudina graminifolia

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42.A.10 Recommended Plants Species for Stream Upper Bank

"&&

Dillenia sp.

Bambusa sp. 'broad leaf Ptychosperma macarthurii             Musa velatino

B

Y

Rhodomyrtus tomentosa

Heliconia psittacorum 'hybird' Piper sarmentosum

J^L       ( liiniul :iM;MiClini J

Crinum asiaticum

Gesneiiaceae sp

Mussaenda erythophylla

Asyiasla saiB'IJ"

Asytasia gangetica

Costus speciosus

Mfnca rosea

(//"Zw/7 Stormwater Management Manual

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42.A.11 Recommended Plants Species for Stream Terrace Face

.. .

Ervatamia corymbosa

Nicolaia clatior           Pandanus sp. 'green dwarf Daemonocarpus angustifolia

Ardisia crispa

Hemigraphis colorata

Lantana camara

Araisia empiica

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42.A.12 Recommended Plants Species for Stream Upper Terrace

Nerium oleander

Heliconia sp.

Croton sp.

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42.A.13 Recommended Plants Species for Ecological Plants/Fruits Bearing Trees

Muntingia calabura

Ardisia crispa

Ardisia elliptica

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42.A.14 Recommended Plants Species for Wild Life Attraction/Breeding Habitat Creation

Leucaena leucoceohaluss

Gesneriaceae sp.

Lantana camara

Ixora javanica

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