Landscape: Site Planning, Contour and Slope, Suitability Analysis, Planting Design, Conservation and Historical Gardens

This chapter answers the second half of AR Part A, Section A.2, “Environmental Planning and Landscape”: “Sustainable site planning; Contour and slope analysis; Landscape planning and design; Landscape suitability analysis; Plant characteristics and planting designs; Landscape conservation - principles and techniques; Social forestry; Historical gardens”. It teaches how a site is read and planned around its drainage, soil, trees and microclimate; how contours give slope, spot levels and cut and fill; the difference between landscape planning and landscape design; McHarg’s overlay method and its weighted GIS form; how plants are described, selected and spaced; the principles and techniques of landscape conservation, with social forestry; and the defining traits of the Persian and Mughal charbagh, Italian, French, English and Japanese gardens and some Indian examples. The numericals are slope from contours, interpolation, balanced earthwork levels, runoff by the rational method, weighted suitability scores and planting counts.

1. Sustainable site planning

Sustainable site planning fits the development to the land instead of reshaping the land to the development. It follows a sequence: inventory (topography, geology and soils, hydrology and drainage, vegetation, climate and microclimate, wildlife, access, views, built and cultural features), analysis (what each factor allows or forbids), synthesis (the parts of the site that suit each use) and design. The governing rule is that the most sensitive land, such as steep slopes, floodplains, wetlands, mature tree stands and good agricultural soil, is protected, and the least sensitive land carries the buildings. Green-building rating systems such as GRIHA and LEED credit these site measures.

  • Keep the natural drainage: retain streams, swales and depressions with vegetated buffers; do not pipe or fill them.
  • Conserve topsoil and trees: strip, stockpile and reuse topsoil; fence mature trees and protect their root zones during construction.
  • Cluster and compact: group buildings on the gentler, drier parts, shortening roads and services and leaving contiguous open space.
  • Work with the contours: align roads and buildings along the contours, minimise cut and fill, and avoid slopes that need heavy retaining structures.
  • Limit imperviousness and manage stormwater on site: permeable paving, bioswales, rain gardens, retention ponds and recharge pits slow, filter and infiltrate runoff (low-impact development).
  • Respond to the microclimate: orient for sun and wind, shade paving and walls with trees, and reduce hard dark surfaces to limit the heat island.

Development turns permeable ground into roofs and paving, which raises the volume and peak rate of runoff and shortens the time of concentration. The rational method estimates the peak discharge: Q = C i A / 360, with Q in m³/s, i the design rainfall intensity in mm/h and A the catchment area in hectares. The runoff coefficient C is the fraction of rainfall that runs off: typically 0.7 to 0.95 for roofs and asphalt and 0.05 to 0.35 for lawns and planted ground (indicative ranges; a problem states its values). For a mixed catchment C is the area-weighted mean, C = Σ(Cₖ Aₖ) / ΣAₖ. Worked example: a 2 ha site has roofs of 0.4 ha (C = 0.90), paving of 0.6 ha (C = 0.80) and lawn of 1.0 ha (C = 0.20). C = (0.36 + 0.48 + 0.20)/2.0 = 0.52, and for i = 60 mm/h, Q = 0.52 × 60 × 2 / 360 = 0.173 m³/s.

⚠️ Units fix the divisor
With A in hectares and i in mm/h the divisor is 360 and Q comes out in m³/s; with A in km² the divisor becomes 3.6. Also, low-impact development does not mean no development: it means cutting runoff at its source and treating it on site rather than piping it away fast, so the peak that reaches the stream is lower than before.

2. Contour and slope analysis

A contour is a line joining points of equal elevation. The contour interval (CI) is the constant vertical distance between successive contours; the horizontal equivalent (HE) is the horizontal distance between two successive contours, measured on the map and scaled up. Together they give the slope: gradient = CI / HE (rise over run), slope % = (CI / HE) × 100, and the angle is θ = tan⁻¹(CI / HE). A slope of 1 in n (1:n) rises 1 for every n horizontal, which is 100/n %. Close contours mean steep ground, wide contours gentle ground, and evenly spaced straight contours a uniform slope. Contours of different levels never cross, except on an overhanging cliff or cave, and water runs downhill at right angles to the contours.

Reading contour shapes
Contour patternLandformPlanning significance
Closed concentric loops, values rising inwardHill or summitProminent, exposed site with views and good drainage
Closed concentric loops, values falling inward, often with tick marksDepression or pitWater collects: risk of flooding and waterlogging
Bends pointing towards lower groundRidge or spurWatershed line; firm, well-drained ground for roads and buildings
Bends pointing towards higher groundValley or stream courseDrainage line with flood hazard and cold-air pooling; keep as a green corridor
Contours bunched into almost one lineCliff or near-vertical faceUnstable and unbuildable; keep clear above and below
Two high pairs and two low pairs of contours facing each otherSaddle or pass (col)Natural crossing point for roads and paths

Worked examples. (1) Two adjacent 2 m contours are 12.5 mm apart on a 1:500 map. HE = 12.5 mm × 500 = 6,250 mm = 6.25 m, so the slope is 2 / 6.25 = 0.32 = 32% (an angle of about 17.7°, or 1 in 3.1). (2) Interpolation. A point P lies between the 100 m and 102 m contours, 18 mm from the lower and 12 mm from the upper, measured along the line of steepest descent. Elevation = 100 + 2 × 18/30 = 101.2 m. (3) Laying out a road. To climb at a gradient of 5% with a contour interval of 1 m, the horizontal run between successive contours must be CI / gradient = 1 / 0.05 = 20 m, so the road line crosses the contours at 20 m spacing.

What slopes mean for planning. Below about 1 to 2% water stands and drains badly, so flat sites need engineered falls. Roughly 2 to 6% suits most buildings, paving and playing fields; 6 to 15% needs terracing, split levels and careful road alignment; beyond about 15 to 20% development is costly, erosion-prone and increasingly unsuitable. These bands are indicative: every study fixes its own, and a problem states them. Accessibility sets hard limits for walking surfaces: a ramp is normally limited to 1:12 (8.33%) with landings, so a rise of 0.6 m needs a ramp at least 0.6 × 12 = 7.2 m long. Mown lawns are generally kept to about 1:3 or flatter, and steeper banks are planted with groundcover or shrubs instead.

⚠️ Vertical interval, horizontal distance
Contour interval is vertical and horizontal equivalent is horizontal; slope is CI divided by HE, so closer lines mean steeper ground. A 1:10 slope is 10%, not 1%, and 100% is 45°, not 90°. Convert the map distance with the scale before dividing. A closed contour does not by itself tell a hill from a depression: read the values or the tick marks.

3. Grading and cut and fill by simple methods

Grading reshapes the ground to fit buildings, roads, drainage and landscape. Proposed contours are drawn as solid lines over the dashed existing ones; where a proposed contour coincides with an existing one there is no earthwork. Cut is excavation below the existing level and fill is placement above it. Good grading balances cut and fill on site, so that soil is not hauled in or out, keeps a minimum fall for drainage on every surface with water directed away from buildings, and sets topsoil aside for reuse.

Simple volume methods. (1) Average end area: between two cross-sections of areas A₁ and A₂ a distance L apart, V = (A₁ + A₂)/2 × L. (2) Spot-level (grid) method: divide the site into squares of side a and, at each corner, find the depth d = ground level − formation level (positive is cut, negative is fill). For one square, V = a² × (d₁ + d₂ + d₃ + d₄)/4. For several squares, V = (a²/4) × (Σd₁ + 2Σd₂ + 3Σd₃ + 4Σd₄), where Σd₁ is the sum over corners belonging to one square, Σd₂ over corners shared by two squares, and so on. (3) Balanced formation level: for equal squares, cut equals fill when the formation level is the weighted mean of the corner levels, H = (Σh₁ + 2Σh₂ + 3Σh₃ + 4Σh₄) / (4n), where n is the number of squares.

Worked examples. (a) A 10 m × 10 m square has corner ground levels 101.2, 100.8, 101.6 and 100.4 m against a formation level of 100.0 m. The mean depth is (1.2 + 0.8 + 1.6 + 0.4)/4 = 1.0 m, so the cut is 100 m² × 1.0 m = 100 m³. (b) Two equal squares side by side have six corners. The four outer corners are at 50.2, 50.6, 50.4 and 50.8 m and the two shared corners at 50.5 and 50.7 m. Σh₁ = 202.0 and Σh₂ = 101.2, so H = (202.0 + 2 × 101.2)/8 = 404.4/8 = 50.55 m. At this level the cut and the fill are equal.

⚠️ Mixed corners and loose soil
The one-line grid formula nets cut against fill, so use it only when every corner of the square has the same sign. If a square has both cut and fill corners, split it along the zero line and compute each part. Also remember that excavated soil swells and fill compacts, so a real earthwork balance applies soil-specific bulking and compaction factors, which a problem will give.

4. Landscape planning and design

Landscape planning works at regional or city scale. It decides what land should be used for what, guided by the land’s capability, ecology, scenery and culture and by policy; its outputs are zoning, green-belt and open-space systems, conservation areas and corridors. Landscape design works at site scale: it gives form, materials, planting and detail to a use that has already been chosen. Planning asks where and why; design asks how the place looks, works and is built.

Landscape elements
GroupExamplesRole
Soft landscapeTrees, shrubs, climbers, groundcover, grassShade, structure, habitat, colour, cooling, infiltration
Hard landscapePaving, steps, ramps, walls, pergolas, kerbsCirculation, enclosure, change of level, durability
LandformGrading, mounds, terraces, swalesDrainage, views, noise screening, definition of space
WaterPonds, fountains, channels, rain gardensCooling, sound, reflection, stormwater storage, biodiversity
Furniture and lightingSeats, signs, bins, lights, sheltersUse, comfort, safety, identity

Design principles are the usual principles of art applied to outdoor space: unity and harmony; balance (symmetrical or asymmetrical); proportion and human scale; rhythm and repetition; contrast; emphasis through a focal point; simplicity; and sequence, the order in which spaces and views are revealed to a moving person. Space is built from three planes: the ground plane (paving, lawn, water), the vertical plane (walls, hedges, trunks, buildings), which encloses and directs, and the overhead plane (canopy, pergola, sky), which shelters. A formal layout uses axes, symmetry and geometry; an informal or naturalistic one uses curves, asymmetry and irregular masses. Either can be right, since the choice follows the setting and purpose.

In large landscapes the language of landscape ecology is used: a landscape is a mosaic of patches (woodlots, ponds, parks), corridors (rivers, hedgerows, greenways) and the matrix, the dominant background such as farmland or built-up area. Large compact patches, joined by wide corridors and softened by buffers and a permeable matrix, keep more species than small isolated ones, so edges and connectivity are the planner’s levers. Landscape character assessment and viewshed (visibility) analysis record what a place looks like and from where it can be seen, so that new development can be fitted into the landscape.

🎯 Planning decides, design delivers
A park drawn beautifully on a floodplain is a design success and a planning failure. The capability and suitability analysis of the next section is what stops the plan placing the wrong use on the wrong land in the first place.

5. Landscape suitability analysis (the overlay method)

Landscape suitability analysis asks which land is best suited to a given use, such as housing, agriculture, recreation or conservation, by combining the factors that matter. Ian McHarg set out the method in “Design with Nature” (1969): map each factor on its own transparent sheet, shade it darker where it is a greater constraint on the intended use (steep slope, flood-prone ground, poor soil, high-value woodland, scenic or historic value), lay all the sheets together, and read the composite. The lightest areas are the most suitable for development; the darkest are the most valuable or most hazardous and are left open or conserved.

  • State the objective and the use being sited (housing, farming, recreation, conservation).
  • Inventory each factor as a separate map: slope, soils, geology, drainage and flood hazard, vegetation, land use, heritage and visual quality.
  • Classify each factor into suitability or constraint classes, with the reasons stated.
  • Overlay the maps, by transparent sheets or by GIS layers.
  • Read the composite, test alternatives and weights, and check the result on the ground.

In GIS the same idea is done as map algebra on raster layers. The simplest form is Boolean (constraint) overlay: a cell is suitable only if it passes every test (AND), for example “slope under 15% and outside the flood line and not woodland”. Weighted overlay scores the classes of each factor on a common scale (for example 1 to 5) and combines them: S = Σ wᵢ rᵢ, where wᵢ is the weight of factor i (the weights sum to 1, or 100%) and rᵢ is the cell’s rating on that factor. Weights are judgements, often derived by a method such as the Analytic Hierarchy Process (pairwise comparison), and a sensitivity analysis shows how far the answer depends on them. Worked example: a cell rates 4 on slope (weight 0.5), 2 on soil (weight 0.3) and 5 on flood safety (weight 0.2), so S = 0.5 × 4 + 0.3 × 2 + 0.2 × 5 = 2.0 + 0.6 + 1.0 = 3.6. With equal weights the score would be (4 + 2 + 5)/3 = 3.67, so the ranking of sites can change when the weights change.

Limits to remember. Equal-weight overlay assumes every factor matters equally. Additive scoring lets a high score on one factor hide a fatal flaw on another (a flood-prone cell with excellent slope and soils still scores well), which is why absolute constraints are applied first, as a Boolean mask. Layers are only as good as their scale and resolution. And the method ranks suitability; it does not itself decide the plan.

⚠️ Dark means constrained, not best
In a development-suitability study the darkest areas on the composite are the most constrained, so they are avoided for building, and they are often exactly the ones worth conserving. Do not read dark as “best” unless the study’s purpose is conservation and the shading was set to show value.

6. Plant characteristics and planting design

Plants are described and chosen by habit and form: trees (a single trunk and a crown), shrubs (several stems from the base), climbers and creepers, herbs and groundcovers, grasses, bamboos, palms and aquatics. By life span they are annuals, biennials or perennials; by foliage, evergreen, deciduous or semi-deciduous. Crown shapes include columnar (a narrow upright crown, as in Polyalthia longifolia, the “false ashoka”), conical, round or oval, spreading or umbrella-shaped (rain tree, banyan) and weeping. Other characters that matter are height and spread at maturity, growth rate, texture (fine, medium, coarse), the colour of leaf, flower and bark, flowering season, root system, and tolerance of drought, shade, salt or waterlogging.

  • Right plant, right place: match the species to climate, soil, light and water, and prefer native or well-adapted species, which need less water and support local birds and insects.
  • Function first: shade (a broad spreading crown), screening (dense evergreen), windbreak (tall, dense, deep-rooted, planted across the wind), noise and dust buffer (a wide, dense belt of mixed layers), erosion control (fibrous, binding roots), accent (fragrance and colour).
  • Mature size and roots: choose by the size at maturity, and avoid large surface-rooting or brittle species close to buildings, drains, services and pavements.
  • Maintenance and safety: consider litter, thorns, toxic or allergenic parts, fruit drop, and the water and pruning needed.
  • Microclimate: shade walls, paving and parking, especially on the west and south-west where the afternoon sun is hot; evapotranspiration cools the surroundings.
  • Avoid invasive species such as Lantana camara or Prosopis juliflora, which crowd out native vegetation.

Planting design arranges plants in space and time. Layer the planting (canopy trees, understorey, shrubs, groundcover) for shade and habitat; group plants in odd-numbered or irregular masses for a naturalistic effect, or in rows and repeats for formal order; repeat species for unity and vary texture and colour for interest; plan for seasonal change, with flowering, fruiting and leaf fall spread through the year; and design for the mature size, not the nursery size. Spacing follows the crown spread: avenue trees are set at roughly their mature crown diameter so that the canopies just meet, and shrubs and groundcover at a spacing that lets them close up within a season or two.

Planting counts. On a square grid with spacing s the number of plants is A / s². In a triangular (staggered) pattern each plant occupies s² × sin 60° ≈ 0.866 s², so the same area holds 1/0.866 ≈ 1.155 times as many plants, about 15.5% more. Along a line of length L with spacing s the number of trees is L/s + 1 if both ends are planted (the fence-post rule), and L/s if only one end is. Examples: groundcover on 45 m² at 0.3 m square spacing needs 45 / 0.09 = 500 plants; an avenue 600 m long, with trees every 12 m on both sides and at both ends, needs 2 × (600/12 + 1) = 102 trees.

⚠️ Fence-post rule and mature size
N intervals need N + 1 plants when both ends are planted, and an avenue planted on both sides doubles the count. Remember also that a tree of the right size on planting day may be wrong for the place twenty years later, which is why the design is drawn for the mature crown and root spread.

7. Landscape conservation and social forestry

Landscape conservation protects the values of a landscape (ecological, cultural, scenic) while allowing it to change in managed ways. Its core principles: identify and document what is valuable before acting; protect the structure of the landscape (its patches, corridors and water systems) rather than isolated spots; keep habitats connected and buffered; use the least intervention that works and prefer reversible measures; respect the authenticity of historic landscapes, their original materials and plant palette; manage change instead of freezing it; and involve the people who live in and use the landscape. Under the World Heritage Convention cultural landscapes fall in three categories: designed, organically evolved (relict or continuing) and associative. The ICOMOS–IFLA Florence Charter (1981) treats a historic garden as a living monument, one whose plants must be renewed over time.

Conservation techniques by problem
ProblemTechnique
Soil erosion on slopesContour bunds and terraces, contour planting, vegetative barriers such as vetiver, mulching, geotextile matting, brush layering and live stakes (bioengineering)
Gullies and stream banksCheck dams and gully plugs, riparian buffer planting, gabions and bioengineered bank protection
Habitat loss and fragmentationRestoration with native species, wildlife corridors, buffers, and protected areas such as national parks, sanctuaries and Ramsar wetlands
Degraded land (mines, landfills, brownfields)Regrading, capping, topsoil spreading, planting of pioneer species, phytoremediation
Historic gardens and designed landscapesSurvey and documentation, a conservation management plan, repair of water systems, replacement of aged trees with the original species, minimal and reversible intervention
Water and groundwaterRainwater harvesting, recharge pits, protection of wetlands and lakes, permeable surfaces

Social forestry means raising trees on non-forest, community and degraded land with the participation of local people, to meet their needs for fuelwood, fodder, small timber and other produce, to reduce pressure on natural forests and to improve the environment. The term came into use in India after the National Commission on Agriculture (1976). Its main forms are farm forestry (trees on farmland and field bunds), community forestry (plantations on village commons, panchayat and wasteland), extension forestry (strips along roads, canals, railways and embankments, and on wastelands), agroforestry (trees grown together with crops or livestock) and urban forestry (parks, avenues, institutional grounds and compact urban woodlands). Its benefits include fuelwood and fodder, shade, windbreaks, soil and water conservation, carbon storage, local employment and biodiversity.

The National Forest Policy (1988) sets the goal of bringing one-third of the country’s area under forest or tree cover, and two-thirds of hill and mountain areas. Joint Forest Management, begun by a 1990 circular, gives village communities a role, and a share of the benefits, in protecting degraded forest. Choice of species is the common weakness: fast-growing exotic monocultures (eucalyptus is the standard criticism) can deplete water, suppress undergrowth and give little fodder, so mixed native multipurpose species are preferred. In cities the Miyawaki method plants a dense, multi-layer patch of native species, commonly two to four saplings per square metre, to produce a compact forest quickly.

⚠️ A plantation is not a forest
Social forestry supplies local needs from non-forest land so that the natural forest can regenerate; it is not the same as protecting natural forest. Planting a single fast-growing exotic over wide areas yields timber or pulp but not the ecological functions of a mixed native stand.

8. Historical gardens

Charbagh (“four gardens”) is the Persian paradise garden: a walled square or rectangle quartered by water channels (echoing the four rivers of paradise) and shaded walks that cross at a central pool or pavilion. Babur brought it to India in the 16th century and laid out riverside gardens at Agra. Mughal gardens then adapted it: on the plains the tomb or pavilion stands at the centre or is moved to the river end, and on hill slopes the garden becomes terraced. Water is made to move: raised channels, cascades down sloping carved chutes (chadar) with niches for lamps and flowers, and fountains driven by gravity or by raised tanks.

Garden traditions at a glance
TraditionLayout and characterWater and plantingExamples
Persian and Mughal charbaghWalled rectangle, strictly geometric, quartered by axial channels or paths that meet at a central pool or pavilion; a symbol of paradiseWater in straight channels, tanks and fountains; cypress, fruit trees and flower beds; pavilionsPasargadae and Fin Garden (Persia); Humayun’s Tomb and the Taj Mahal garden; Shalimar Bagh, Lahore
Italian RenaissanceHillside villas; terraces stepping down a strong central axis that links house, garden and view; architecture and garden composed as oneCascades, fountains and water tricks; clipped evergreen hedges, parterres, statues and grottoesVilla d’Este, Tivoli; Villa Lante, Bagnaia; Boboli Gardens, Florence
French formalVast level sites; a grand axis from the château with radiating avenues; symmetry and geometry that dominate the landscape; long vistasGrand canal and basins, parterres de broderie, clipped groves (bosquets) and tree-lined alléesVaux-le-Vicomte and Versailles, by André Le Nôtre
English landscapeEighteenth-century reaction against formality; naturalistic and picturesque, with sweeping lawns, clumps of trees, winding paths and a ha-ha to hide the boundarySerpentine lakes and streams; temples, bridges and follies as eye-catchersStowe and Stourhead; Lancelot “Capability” Brown (Blenheim among others), William Kent, Humphry Repton
JapaneseShaped by Shinto, Buddhism and Zen; a symbolic miniature of nature; asymmetry, restraint and borrowed scenery (shakkei)Ponds, streams, raked gravel standing for water in dry gardens, rocks, moss, pines, maples, lanterns and stepping stonesKatsura Imperial Villa (stroll garden); Ryoan-ji, Kyoto (dry garden); tea gardens (roji)
  • Humayun’s Tomb, Delhi (1560s to 1570s): the first monumental garden tomb of the Mughals in India, a charbagh with the mausoleum at the centre of four quarters, each further divided by paths and channels.
  • Taj Mahal, Agra (17th century): the tomb stands at the river end of a large charbagh rather than at its centre, so the Yamuna forms the backdrop and the central raised water channel leads the eye to it; the Mahtab Bagh lies across the river.
  • Shalimar Bagh and Nishat Bagh, Srinagar (17th century): terraced gardens climbing the slope from Dal Lake, with a central water axis, cascades and chinar trees. Shalimar Bagh, Lahore (1640s) has three descending terraces.
  • The Mughal Garden at Rashtrapati Bhavan, Delhi (now Amrit Udyan): laid out in the early twentieth century with Edwin Lutyens’s Viceroy’s House, combining Mughal charbagh geometry and water channels with English lawns and flower beds.
  • Lalbagh, Bengaluru (begun in the 18th century under Hyder Ali): a botanical garden, formal in part and landscape in part, with a Glass House added in the 19th century.
  • Ashoka’s edicts record roadside planting of banyan trees and mango groves and the digging of wells, an early example of avenue planting for shade.

Japanese gardens come in four common types: the stroll garden (kaiyū-shiki), walked around a pond with changing views; the dry garden (karesansui), in which raked gravel stands for water and rocks for islands or mountains; the tea garden (roji), whose stepping stones lead to the tea house; and the courtyard garden (tsubo-niwa). The 11th-century Sakuteiki is the oldest surviving Japanese garden treatise. The English landscape garden removed straight lines: William Kent and then Lancelot “Capability” Brown shaped lawns, lakes and clumps of trees into a natural-looking scene, and the ha-ha, a sunken ditch with a retaining wall, kept livestock off the lawn without a fence to interrupt the view. Repton recorded his proposals in his “Red Books”.

🧠 One trait each
Tell the traditions apart by one trait each. Persian and Mughal: a walled four-part layout organised by water channels. Italian: terraces on a slope joined by a central axis, with cascades and fountains. French: a flat site with a grand axis, radiating avenues and parterres, nature ruled by geometry. English: no straight lines, a ha-ha, a serpentine lake and clumps of trees. Japanese: a symbolic, asymmetrical miniature of nature built from rocks, gravel, water and moss.

Key takeaways

  • Site planning protects the most sensitive land (drainage lines, floodplains, steep slopes, mature trees, topsoil) and builds on the least sensitive. Peak runoff by the rational method is Q = CiA/360, with the area-weighted runoff coefficient.
  • Slope % = (CI/HE) × 100, with HE taken from the map at its scale. Contours bend towards lower ground on a ridge and towards higher ground in a valley, and interpolation between contours is linear.
  • Grid cut and fill uses V = a²Σd/4 for one square, and the balanced formation level is the weighted corner mean; the net formula is valid only when every corner has the same sign.
  • Landscape planning decides where and why; design decides how. In McHarg’s overlay dark means constrained, and in weighted overlay S = Σ wr the ranking of sites can change with the weights.
  • Choose plants for function, mature size, roots, native adaptation and low maintenance, and avoid invasive species. Spacing follows crown spread, and counts use A/s² for a grid and L/s + 1 along a line planted at both ends.
  • Conservation protects structure, connectivity and authenticity with minimal, reversible intervention, and social forestry grows trees on non-forest land with people’s participation. Charbagh is a walled four-part water garden; Italian is terraced; French is flat and axial; English is naturalistic with a ha-ha; Japanese is symbolic and asymmetrical.

Practice questions (20)

Attempt each one before opening the answer. Every explanation names the tempting wrong option as well as the right one, because that is where marks are lost.

  1. On a contour map, contours that are drawn very close together indicate

    1. a flat plateau, because many levels are crowded into a small area
    2. steep ground, because the same vertical interval is covered in a short horizontal distance
    3. a gentle slope, because the closeness of the lines shows that the change in level is small
    4. a depression, because contours always crowd together around a pit
    Show answer

    Answer: B — steep ground, because the same vertical interval is covered in a short horizontal distance

    The contour interval is constant, so a short horizontal equivalent means a large gradient: close contours show steep ground. A plateau or gentle slope has widely spaced contours, and a depression is recognised by falling values, not by spacing.

  2. A contour map shows a series of V-shaped bends, all pointing towards higher ground. The landform is most likely

    1. a ridge or spur, since the contours on a ridge bend towards higher ground across its crest
    2. a hill summit, since V-shaped bends occur where the contours close around a peak or knoll
    3. a cliff, since contours bunch into V shapes where they cross the vertical face of a scarp
    4. a valley or stream course, since contours bend upstream across a drainage line
    Show answer

    Answer: D — a valley or stream course, since contours bend upstream across a drainage line

    In a valley the contours cross the drainage line and bend upstream, so the Vs point uphill, towards higher ground. On a ridge or spur the bends point towards lower ground, which is the tempting reversal. A summit shows closed loops, and a cliff shows contours merging into almost one line.

  3. A ramp has to rise 0.9 m at a gradient of 1 in 12. The minimum horizontal length of the ramp is

    1. 7.5 m
    2. 9.0 m
    3. 10.8 m
    4. 12.0 m
    Show answer

    Answer: C — 10.8 m

    A gradient of 1 in 12 needs 12 m of horizontal run for every metre of rise, so the length is 0.9 × 12 = 10.8 m. Dividing 0.9 by 0.12, which treats the gradient as 12%, gives 7.5 m and is the usual error; 1 in 12 is only 8.33%.

  4. A 12 ha site slopes gently to a seasonal stream, has a belt of mature trees along a ridge and fine agricultural soil in its flat north-west corner. Which approach best fits sustainable site planning?

    1. Cluster the buildings on the gently sloping, well-drained middle ground clear of the stream and flood line, keep the tree belt and a stream buffer, and conserve the topsoil
    2. Grade the whole site to a single flat platform for easy construction, and pipe the seasonal stream below it so that the land above can be used in full and drained quickly
    3. Locate the buildings on the flat north-west corner because level land is cheapest to build on, and clear the tree belt to make room for the roads and for parking
    4. Spread low-density plots evenly over the whole site so that no part is left to a single user, and drain each plot straight into the stream through its own outlet
    Show answer

    Answer: A — Cluster the buildings on the gently sloping, well-drained middle ground clear of the stream and flood line, keep the tree belt and a stream buffer, and conserve the topsoil

    Sustainable site planning protects the most sensitive land (the stream and its buffer, the tree belt and the good farm soil) and builds on the least sensitive, gently sloping, well-drained ground, with the topsoil conserved. Building on the best soil and clearing the trees wastes both, while flattening the site and piping the stream add earthwork and raise flood risk downstream.

  5. Which of the following statements about contours are correct? Select all that apply.

    1. Contours of different levels never cross, except at an overhanging cliff or cave.
    2. Water running over the ground follows the steepest line, at right angles to the contours.
    3. Equally spaced straight contours indicate a uniform slope.
    4. A closed contour always indicates a hill.
    Show answer

    Answer: A — Contours of different levels never cross, except at an overhanging cliff or cave.; B — Water running over the ground follows the steepest line, at right angles to the contours.; C — Equally spaced straight contours indicate a uniform slope.

    The statements on non-crossing, on steepest-descent flow and on uniform slope are standard properties of contours. A closed contour can equally mark a depression, and only the values, or tick marks showing the downhill side, tell the two apart.

  6. Which of the following measures reduce stormwater runoff from a developed site? Select all that apply.

    1. bioswales and rain gardens that slow the water and let it infiltrate
    2. keeping the existing vegetation and topsoil so that infiltration is not lost
    3. replacing the natural stream channel with a buried pipe so that water leaves the site faster
    4. grading the whole site to a uniform fall towards the nearest road drain
    Show answer

    Answer: A — bioswales and rain gardens that slow the water and let it infiltrate; B — keeping the existing vegetation and topsoil so that infiltration is not lost

    Bioswales, rain gardens and retained vegetation and topsoil slow and soak up rain at its source, which is low-impact development. Piping the stream and draining everything quickly to a road drain does the opposite: it raises the peak and volume of runoff.

  7. Two adjacent contours 5 m apart in elevation are 16 mm apart on a 1:2500 map. The ground slope, in percent to one decimal place, is ____.

    Numerical answer — type the value.

    Show answer

    Answer: 12.5

    HE = 16 mm × 2500 = 40,000 mm = 40 m. Slope = CI / HE = 5 / 40 = 0.125 = 12.5%. Forgetting to apply the map scale would give nonsense, since 5 m cannot be divided by 16 mm.

  8. A point P lies between the 64 m and 66 m contours. Measured along the line of steepest descent it is 9 mm from the 64 m contour and 21 mm from the 66 m contour. Assuming a uniform slope, the elevation of P in metres, to one decimal place, is ____.

    Numerical answer — type the value.

    Show answer

    Answer: 64.6

    The two contours are 9 + 21 = 30 mm apart and differ by 2 m. P is 9/30 of the way up, so elevation = 64 + 2 × 9/30 = 64 + 0.6 = 64.6 m. Using 21/30 instead measures from the wrong contour and gives 65.4 m.

  9. Two equal square grid cells lie side by side, giving six corner points. The four outer corners have ground levels 100.0, 100.4, 100.2 and 100.6 m, and the two shared corners have 100.3 and 100.5 m. The formation level that balances cut and fill, in metres to two decimal places, is ____.

    Numerical answer — type the value.

    Show answer

    Answer: 100.35

    Σh₁ (corners in one square) = 100.0 + 100.4 + 100.2 + 100.6 = 401.2; Σh₂ (corners shared by two squares) = 100.3 + 100.5 = 200.8. H = (Σh₁ + 2Σh₂)/(4n) = (401.2 + 2 × 200.8)/8 = 802.8/8 = 100.35 m. A plain average of the six levels (100.33) ignores that the shared corners count twice.

  10. A 4 ha catchment has 1.0 ha of roofs (C = 0.90), 1.0 ha of paving (C = 0.80) and 2.0 ha of garden (C = 0.15). For a design rainfall intensity of 72 mm/h, the peak discharge by the rational method, Q = CiA/360 (A in ha, i in mm/h), in m³/s to one decimal place, is ____.

    Numerical answer — type the value.

    Show answer

    Answer: 0.4

    Composite C = (1.0 × 0.90 + 1.0 × 0.80 + 2.0 × 0.15)/4 = (0.90 + 0.80 + 0.30)/4 = 2.0/4 = 0.50. Q = 0.50 × 72 × 4 / 360 = 144/360 = 0.4 m³/s. Using the unweighted mean of the three coefficients (0.617) would be wrong, because the garden is half the area.

  11. In McHarg’s transparent-overlay method for a development-suitability study, a very dark area on the composite sheet indicates

    1. land with the greatest suitability for building, since many of the factors favour it and few constrain it
    2. land where the factors have not yet been mapped and so need further survey before any decision
    3. land that is already built up and should be redeveloped before any new land is used for the purpose
    4. land that is strongly constrained or highly valued for the intended use, to be kept open
    Show answer

    Answer: D — land that is strongly constrained or highly valued for the intended use, to be kept open

    Each sheet is shaded darker where its factor resists the intended use, so overlapping darkness means many constraints or high value, and such land is kept open or conserved. Reading dark as best is the tempting error; the lightest zones are the suitable ones.

  12. Two candidate sites are rated from 1 to 5 (5 is best) on slope, soil and flood safety. Site P scores 5, 3 and 2; site Q scores 3, 4 and 4. First with weights of 0.5, 0.3 and 0.2 respectively, and then with equal weights, the higher-ranked site is

    1. P with both sets of weights
    2. Q with both sets of weights
    3. P with the given weights, and Q with equal weights
    4. Q with the given weights, and P with equal weights
    Show answer

    Answer: C — P with the given weights, and Q with equal weights

    With weights 0.5, 0.3 and 0.2: P = 2.5 + 0.9 + 0.4 = 3.8 and Q = 1.5 + 1.2 + 0.8 = 3.5, so P ranks first. With equal weights: P = (5 + 3 + 2)/3 = 3.33 and Q = (3 + 4 + 4)/3 = 3.67, so Q ranks first. The ranking flips because P is strong on the heavily weighted slope factor, which is why a sensitivity analysis on the weights is done.

  13. For an avenue tree beside a footpath with a buried drain and a compound wall, which trait should the designer avoid?

    1. a broad, spreading crown that gives dense shade over the footpath and the carriageway
    2. aggressive surface roots together with brittle branches that break in storms
    3. a deep root system with limited lateral spread close to the compound wall and drain
    4. a native species that is adapted to the local rainfall, soil and temperature range
    Show answer

    Answer: B — aggressive surface roots together with brittle branches that break in storms

    Surface roots lift paving and invade drains and walls, and brittle limbs fall on people and vehicles, so such species are avoided close to services. A broad shady crown is the main purpose of an avenue tree, a deep root system is welcome near structures, and a native species adapted to the site is preferred.

  14. Social forestry, as introduced in India, mainly aims to

    1. raise trees on non-forest, community and degraded land with local participation, for fuelwood, fodder and small timber, easing pressure on natural forest
    2. convert existing natural forests into commercial plantations of a single fast-growing exotic species to supply the timber and pulp industry
    3. confine all tree planting to notified reserved forests managed by the forest department, without any involvement of local people or panchayats
    4. replace village common land with fenced timber estates owned by private companies, so that all the timber can be sold for export
    Show answer

    Answer: A — raise trees on non-forest, community and degraded land with local participation, for fuelwood, fodder and small timber, easing pressure on natural forest

    Social forestry is about people: planting on land outside the forest, with the community, for its own needs, so that the natural forest is relieved. Converting natural forest to monoculture, restricting planting to reserved forests, or fencing commons for private estates is the opposite of its aims.

  15. A hill-slope watershed shows rill and gully erosion on cultivated land, silting of a village tank downstream and little vegetation cover. Which response best fits the principles of landscape conservation?

    1. Contour bunds or terraces and vegetative barriers such as vetiver on the slope, check dams in the gullies, and tree and grass cover raised with the villagers
    2. Concrete lining of the gullies and yearly desilting of the village tank, leaving the cultivated slope as it is and its soil unprotected
    3. Ploughing up and down the slope after clearing the remaining shrubs, so that rain drains off the fields quickly and the land dries sooner for sowing
    4. Fencing the whole watershed to keep the community out, and relying on natural regeneration alone for the next several decades
    Show answer

    Answer: A — Contour bunds or terraces and vegetative barriers such as vetiver on the slope, check dams in the gullies, and tree and grass cover raised with the villagers

    Treat the cause where the water starts: slow runoff on the slope with bunds, terraces and vegetative barriers, stabilise the gullies with check dams, and restore cover together with the people who depend on the land. Lining gullies and desilting the tank treat only the symptoms, ploughing up and down the slope speeds erosion, and excluding the community removes the stewardship that keeps the measures maintained.

  16. Which of the following are recognised forms of social forestry? Select all that apply.

    1. commercial timber plantations inside a notified wildlife sanctuary
    2. extension forestry along roads, canals and railway lines
    3. farm forestry on field bunds and farm boundaries
    4. community forestry on village common and wasteland
    Show answer

    Answer: B — extension forestry along roads, canals and railway lines; C — farm forestry on field bunds and farm boundaries; D — community forestry on village common and wasteland

    Extension, farm and community forestry are the standard forms: trees on roadsides and canal banks, on farm bunds, and on village commons and wasteland. Commercial timber plantations inside a wildlife sanctuary are neither social forestry nor permitted by the sanctuary’s purpose.

  17. A road 450 m long is to be planted with avenue trees at 15 m centres on both sides, with a tree at each end of each side. The total number of trees required is ____.

    Numerical answer — type the value.

    Show answer

    Answer: 62

    Intervals per side = 450/15 = 30, and with a tree at both ends the trees per side = 30 + 1 = 31. Both sides: 2 × 31 = 62. Answering 60 forgets the extra end tree (the fence-post rule).

  18. The defining organising device of a Persian–Mughal charbagh is

    1. terraces stepping down a hillside along one central axis, joined by cascades and fountains
    2. avenues radiating from a château across level land towards long vistas and a distant horizon
    3. a walled rectangle quartered by water channels and paths meeting at a central pool or pavilion
    4. a serpentine lake and clumps of trees, with a hidden ditch separating garden from pasture
    Show answer

    Answer: C — a walled rectangle quartered by water channels and paths meeting at a central pool or pavilion

    Charbagh means four gardens: a walled plan divided into four by channels and walks that meet at the centre, recalling the four rivers of paradise. Stepped terraces with cascades describe the Italian villa garden, radiating avenues the French formal garden, and the serpentine lake with a hidden boundary ditch the English landscape garden.

  19. A garden on a large level estate has a grand axis running out from the house, a long canal, elaborately clipped parterres and avenues radiating from a central point. It belongs to the tradition of

    1. the Italian Renaissance villa garden, laid out on terraces cut into a hillside
    2. the French formal garden, as designed by André Le Nôtre at Versailles
    3. the English landscape garden, as shaped by Capability Brown at estates such as Blenheim
    4. the Japanese dry garden, as built at Zen temples in Kyoto using raked gravel
    Show answer

    Answer: B — the French formal garden, as designed by André Le Nôtre at Versailles

    A flat site, a dominant axis, a grand canal, parterres and radiating avenues are the signature of Le Nôtre’s French formal style, as at Vaux-le-Vicomte and Versailles. Italian gardens exploit slopes with terraces, English landscape gardens avoid straight lines, and Japanese dry gardens are small and symbolic.

  20. Which of the following pairings of garden tradition and defining feature are correct? Select all that apply.

    1. Persian–Mughal charbagh: a walled four-part layout organised by water channels
    2. Italian Renaissance: terraces on a slope joined by a central axis, with cascades and fountains
    3. English landscape garden: strictly symmetrical parterres around a straight grand canal
    4. Japanese garden: an asymmetrical symbolic miniature of nature, using rocks, gravel, water and borrowed scenery
    Show answer

    Answer: A — Persian–Mughal charbagh: a walled four-part layout organised by water channels; B — Italian Renaissance: terraces on a slope joined by a central axis, with cascades and fountains; D — Japanese garden: an asymmetrical symbolic miniature of nature, using rocks, gravel, water and borrowed scenery

    The charbagh, the Italian terraced villa garden and the Japanese symbolic garden are matched correctly. Strictly symmetrical parterres around a straight canal belong to the French formal garden; the English landscape garden was a reaction against exactly that geometry.