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Sustainable Urban Environmental Planning - Community Plans Contents by Anne Beer, Professor Emeritus University fo
Sheffield
The Environmental Inventory and assessing the implications of the findings for sustainable local communities
The physical environment: abiotic data collection
Information must be gathered about the local geology, geomorphology and climate, as well as the topography and soil. This data is needed as it sets some of the limits on human action: if we are to treat our local environments in a sustainable manner, the potential for development of an area of land is determined as much by local physical environmental characteristics as people's needs for places to live, work and play. Nowadays this is reinforced by the internationally recognised need to maintain biodiversity (UN, 1993) and the natural potential for that too is limited by the physical environment. In developed countries, much of the data is likely to be available in a published format, so this stage of the environmental planning process can often be done relatively quickly. Where data is not available, 'best guesses' based on local people's knowledge of their environment, on air photographic records and on interpretations by local experts may have to suffice. When full data is not available you should use your own knowledge as well as that of local experts to decide what it is really important locally. For instance, you might find that landslips are the main problem that has been identified, or that flooding is a major concern; in such circumstances you need to concentrate your efforts on gathering information about these 'special' issues. Checklists for your guidance are detailed below; you should adapt these to your situation and rarely expect to gather the full range of data listed here.
DATA CHECKLISTS
a. Local geological and topographic information
A preliminary check should be made on the local surface geology, aquifers, water table and fluctuations, mining and waste tips, landfill sites and mineral reserves with the intention of identifying the important issues for your particular project. A quick consideration of the implications of the local topography also needs to be undertaken. For instance:
• the link between the angle of slope and aspect, the impact of elevation on land use • the presence of any unstable land and any bearing capacity problems which may limit the use of any parts of the site. It is important not just to gather data for the sake of it - gather only what you really need. Check the geology from published maps where possible, otherwise ask local experts. In particular, examine the surface geology for any clues as to the past, present and future use of the study area. To assess the implications for local land use of the geology, discuss your findings with local expert geologists.
Assessment of the implications of the local geology in relation to the sustainable use of land The following may seem a long list but only a small part is likely to concern your particular site. The skill is in working out what is important locally and until you have that skill you will need to check everything.
Bearing capacity If geological expertise is unavailable, use Figures 4.1 and 4.2 (see Chapter 4) for preliminary guidance on any bearing capacity problems within the project site which might limit the possible expansion of development. Identify any areas of friable rock/loosely consolidated materials or peat, as these will mean higher construction costs if the areas are developed. Geological faults Pay attention to faultlines, since any major structures built in their vicinity suffer structural failure, even when only minor earthquakes occur, unless properly engineered. Outcrops of rock Record location and type of rock outcrops on the site. Record areas of hard rock or boulder strewn land on or near the surface as these may limit certain forms of development. Assess any quarrying or recreational potential of outcrops. Aquifers and the watertable Establish whether ground water surfaces in ponds, lakes or springs within the study area, since in such circumstances additional protection of water quality will be important. Establish whether a high water table exists: this is normally associated with wetland and such areas can be of importance when developing a local biodiversity strategy. Establish whether any water for human or industrial use is drawn from a near surface ground water storage area and assess the need for special measures to protect the recharge surface. Establish whether the project site lies over a water-recharge area for a deep aquifer (consult the local water board or local geologists). If so, this severely limits what can be allowed to occur on the surface of the land in terms of use of pesticides and other chemicals, and also in terms of the need to maintain porosity of the surface. Waste tips, old mine workings and quarries Note the location on site of any waste tips from dumping material from household waste, mining or other operations and assess whether they are potentially toxic. If so, arrange a chemical analysis with a view to re-working or removing, or otherwise making the site safe for human use. Record any waste tips, old mine workings, or quarries within and around the study area. Establish whether over or underground water from these tips enters water courses in the study area and assess whether the water is likely to be polluted. Record location of old mine shafts, capped or uncapped and evaluate safety issues. Mineral reserves Check the geological survey and if any quarrying of minerals occurs discuss with local experts the future economic value of materials found in the study area, e.g. gravel, sand, coal and other raw materials. Assess the potential for their use locally in construction or manufacturing to minimise the environmental damage associated with the long haul of natural resources.
Assessment of the implications of geomorphological processes River erosion Note the rate of erosion and deposition along rivers and any signs of unstable river banks and assess the possibility of changing land use or land management regimes to reduce any adverse effects. Record any erosion of cliffs, if the site is near the sea and get expert help to assess the implications of climatic change and associated sea level changes for the rate of erosion or for flooding. Landslips Record all known landslips and discuss the cause and likelihood of recurrence with local experts. Assess the implications of land use changes, including any possible deforestation. In particular record the location of any unconsolidated material at present held in place by vegetation and consider whether existing or proposed development near such areas could accelerate erosion and cause conditions hazardous to human welfare.
b. Topography
It is important that anyone working on an environmental planning project visits the study area often; you need to develop a real 'feel' for the lie of the land. This understanding of the hummocks and hollows, the general shape of the area, how some parts of it slope towards the midday sun and others are almost always in shade, is vital to the success of detailed environmental planning at local or community level. It is a major part of the understanding of the local area which is needed by those making environmental planning decisions; it is essential to developing any 'sense of place'. Detailed information about topography can help to identify the best positions for buildings and a whole range of outdoor activities and also help to identify which areas of existing and new development are exposed to the elements to the detriment of energy conservation measures.
Recording the lie of the land As well as familiarising yourself with the local landscape by walking through it, you will find that drawing a contour map will help you get a feel of the shape of the land, as will drawing several cross sections through your site and the land which surrounds it. The more complicated the study area, the more cross sections are needed to understand how existing development sits in the local landscape. Cross sections should be drawn across the contours and also along them. Draw the cross sections to scale, with no vertical exaggeration. On a base map for the project area you should:
highlight any flat areas; note if these coincide with waterlogged areas indicating poor drainage show the extent of any steeply sloping areas show the position and extent of any high points: ridges or hilltops. It is important that you record even very minor ridges, as these can help you to make the final decisions on the best location and extent, for instance, of new woodland planting or new development. show the location of cliffs or quarry faces add water courses to your plan and indicate the position of any weirs, dams or waterfalls. Take care to record the way the land lies along the edges of all water bodies, as this will influence where access can be arranged.
Visual enclosure As you walk round the study area, identify the extent of any areas in which you are aware of feeling totally or partially enclosed. Indicate the areas on a base plan of the site. Write notes on your plan to describe the different types of enclosure and the views experienced in different parts of the site. This information will be useful when developing an effective strategy for recreational use of the study area.
Slope analysis The information you have gathered about the lie of the land can be used to produce a diagram to highlight the site's main features with regard to slope. It is useful for the environmental planning process to produce a diagram which shows the location of the vertical and near vertical banks, the very steepest land, steep land, moderately sloping land, gently sloping land and flat land. If this is the first time that you have done a slope analysis and you are as yet unclear about the implications of slope in relation to the proposed use of the project area, you could use the following categories to prepare a slope analysis diagram:
less than 1:100 1:40-1:100 1:20-1:40 1:10-1:20 1:7-1:10 1:5-1:7 more than 1:5
Indicate on the plan the direction of slope on the diagram - this is called aspect of the slope and it is important in relation to environmental sustainability, as, together with the angle of the slope, it links directly with calculating energy consumption within buildings. It also has a strong influence on which areas of a site are good for outdoor uses.
c. Climate and hydrology
It is useful to gather data on temperature and humidity variations, sun hours, wind patterns, event occurrences: droughts, snow days and frost days. The aim of this is to help you to identify characteristic local variations and extremes and any particular problems caused to local urban development by the local climate.
Climate statistics In order to have some idea of the variations that could be expected in the local climate and the problems that these might cause in relation to increasing the sustainability of local land uses, you should consider the following issues with the help of climatic data from the nearest weather station to your site and establish whether there are any potential local problems in relation to:
the average temperatures for each month of the year the average number of hours of sunshine in each month the cloud cover expected at different times of the year the average rainfall for each month the average number of days when frost occurs the average number of days when fog occurs the average number of days when snow lies and the expected depth the average number of days when drought conditions are to be expected the lowest and highest temperatures experienced the humidity level throughout the year the diurnal range (the daily fluctuation in temperature).
Drawing a wind-rose (a diagram showing the directions the wind blows and the frequency of wind from each point of the compass) will help the decision making process later, as it will indicate the need to design for shelter from certain winds.
Assessing the climate data to identify the warmer and colder areas The basic climatic data about an area will help you to develop a sustainable approach to energy consumption, to develop a sustainable layout of any new built forms, to identify where shelter belt schemes might be appropriate and help you plan the use of outdoor spaces throughout the year. You will find it useful to locate:
the slopes that face the sun the slopes that face away from the sun the areas exposed to the most common cold winds potential frost hollows and where fog is likely to accumulate areas where there might be a problem with drifting snow.
Look at wind patterns, shade and shelter, as well as direction of slope and aspect, to establish an understanding of the microclimate within the study area. You will find that the diagrams and plans that you produce at this stage can be a very useful guide at the decision making stages in relation to encouraging effective and sustainable land use and land management change.
Interpreting local hydrological information New ways of managing our use of water are central to developing approaches to more sustainable living. To add useful information to your database on water related issues, you need to use the data gathered on local rainfall patterns as part of your consideration of local climate, and to link this with the maps of surface water and slopes which you will have made when considering topography. This will enable identification of the extent of the water sheds for each stream and an assessment of the normal and likely peak flows. In general terms, the larger the watershed the more water will enter the valley and streams in times of peak rainfall. It is also useful, if you can, to consider the information you gathered when looking at the local geology about aquifer recharge areas, water extraction patterns, surface flows, catchments areas, floodland and flash flooding frequencies, as well as how the local surface and foul water is dealt with by the sewerage system. In many developed countries there has been an increasing tendency in recent decades to build ever larger sewage disposal plants. While this might have seemed the most efficient way in engineering and economic terms to ensure a better quality of effluent from the cities, in fact it has caused many unforeseen environmental sustainability problems. The main problem that emerged was that it was uneconomic to build the new plants of sufficient size to cope with the throughput at extremes of flash flooding. So at such times these new 'state of the art' plants create an overflow of untreated or partly treated effluent into the local water courses. This leads to severe damage to the biota in the affected streams. Fortunately such occurrences are rare, but there is concern that the problem will worsen with increased extremes of rainfall due to global warming. In Germany there has been much experimentation with a return to local (preferably at source) treatment of effluent; this approach is proving very sustainable, since it reduces all the risks to the environment from the inadequate operation of the large 'state of the art' major city water cleansing systems. Failure to take account of flooding in the development of land in recent times is inexcusable and yet it has occurred in many countries. Developers blame the local authorities for letting them build in vulnerable areas and local authorities blame the developers for not taking proper care to study the sites that they want to develop. The cost to society of coping with damage from flooding is very considerable in many countries and an unnecessary cost if proper environmental planning had been done in the first instance. Flood risk can be assessed in a straightforward way and in the UK it is now the Environment Agency's task to carry this out and make the information available to the public. In addition to awareness of the potential for flooding within your study area, it is also important to consider the implications of flood protection; these always need to be considered carefully, since all that happens when one area is protected is that the problem is pushed elsewhere - the water does not just disappear. It also useful to be aware that the flood risk in some areas of land has been accentuated through increased density of development. This is because the percentage of the land surface that is sealed (built over or paved) tends to increase with density. Sealed surfaces allow water to move across them quickly, filling the drainage system and flash flooding the ditches, streams and rivers, so disturbing the biota and the self cleansing mechanisms of the water. Opening up the surface again wherever possible and allowing the water time to soak into the soil, is a much more sustainable and economic approach. It reduces the need to spend so much money on artificial drainage systems, in turn saving on the use of so much cement and concrete (itself a sustainable action to protect scarce resources). An added reason for encouraging expansion in the extent of unsealed surfaces is that it is better for water cleansing if water is filtered through the soil before it reaches the surface water channels and, therefore, also better for biodiversity. Much work has been carried out to develop environmentally friendly approaches to water management (Lyle, 1994). Whether it is appropriate to use more unsealed surfaces, expand the local ditch system, or introduce more soakaways, reedbeds, etc. will depend on local circumstances. An important aim for a Community Environmental Plan is to make a local community aware of the possible options.
Surface water systems, water quality and pollution
Prepare a base map of the site showing:
the total surface drainage system and any areas of still water the water catchment area that feeds each local stream/river/pond. Where a study area is liable to flood, it is essential for you to establish how regularly such floods normally occur in the local river system and the area of land commonly affected. Show on a plan:
• the maximum extent of the yearly flood • the maximum it averages over a five year period, a ten year and a hundred year period, as estimated by the local experts. If the flooded area has been known to be larger, then map the maximum known extent of flooding. If no information is available, yet it appears from your study of the river system that there might be a problem, talk to local people to establish which, if any, houses have been inundated in the recent and distant past. In areas with flood problems note what has been done to control flooding and what, if any, flood protection measures it is intended to implement in the future. Record any official information available on water quality and assess what this means in terms of how the water can be used (contact the local water board and Environment Agency, or other responsible authority). Find out, for instance, whether it is safe to drink, or for swimming and water sports. For small water bodies which are not controlled by any public or private water agency, find out how polluted the water is:
does the water smell, if so how foul is it? (Work out why it smells - it is often a symptom of water not coping with the present level of pollution. Remember that temperature and water availability conditions can vary at different times of the year and these natural fluctuations will affect the likelihood of smells becoming a problem). does algae (the green slime that settles on the top of the water when there is not enough oxygen in the water) or weed grow on the surface? (If so, is there any indication that the local land users are being too liberal in their use of chemicals?) A public education project may need to be initiated. note by taking a sample how clean the water looks, look for foreign material held in the water - soil, bits of vegetation, dirt - too much material, such as earth washed off bare ground, held in suspension means the water cannot self cleanse and, therefore, cannot cope with pollution does it, at least at first glance, seem an attractive area of water associated with plenty of wildlife and plants? record whether the water is slow and sluggish or fast and bubbling over rocks and pebbles. You can calculate the flow crudely by measuring the time it takes for a float to travel a given distance of 10 metres. Water speed needs to be timed at several points across a stream to find the area of fastest flow (water bubbling over a rough surface is being oxygenated and this increases its capacity to self cleanse; adding artificial small weirs is a simple way to enhance water quality). Assess the water bodies' capacity to be self cleansing under the present circumstance and in relation to what is known about any proposed land use and land management change. If the evidence seems to imply a doubt about a water body's ability to cope with pollution and remain self cleansing, experts should be consulted and appropriate water management techniques developed. When you make notes, remember to indicate that you are making a subjective judgement. If it appears there is a problem and no information is available, a proper water quality analysis will have to be carried out by experts, particularly if the water is to be used for human consumption, or leisure.
Canals, ponds, lakes and wetlands It is also important for environmental planning purposes to know where all the ponded water is within the project area. Detailed information needs to be gathered on the water quality of all such still water. An assessment needs to be made of the wildlife value, recreational value and permanence of the feature - they are often areas of considerable importance for biodiversity. Record how each pond, lake, wetland etc. is fed by water and how it is drained. Be alert to changes in drainage patterns which might mean that overflow from road drains is let into such water bodies, as this can have disastrous consequences for nature and the ability of the water to self cleanse. The condition of the edges and the degree of shading play a part in their ecological and recreational usefulness.
d. Soils
Gather information on soil acidity, soil texture, soil fertility, soil water content and toxic soils.
Note: soils are included here under the Abiotic section for ease of description, but of course there is considerable overlap with Biotic factors because of the capacity of the soil to support such a wide range of biota.
The identification of soil types If any published soil information is available it is useful to record it; however, it is unlikely that such information will be in much detail. If you have no access to a soil scientist for an interpretation of the information, you will probably find it most useful to talk to the local farmers and those who work any local allotments or gardens about the quality of the local soils.
How to gather basic information about the soils You will need to consult the experts about the capabilities of the different soils on the site; this is only important if any part of it is to be cultivated for crops or to grow food. If growing food or other crops including trees is an important consideration, carry out the soil fertility and soil erosion surveys below and make a brief assessment of what the findings mean in relation to the future land management development of the site. It is always important to know where the contaminated soil is, even in urban areas, so that health protection measures can be taken.
Soil fertility If accurate information is required because the site will be used for growing crops, soil scientists need to be consulted. If only general guidance on relative fertility is necessary, a useful but very rough estimate of the relative soil fertility within a site can be made by non-experts looking at the information available from the soil pits. There are two easily identifiable indicators of high fertility and if these are present it is likely that the soil on your site will be a good growing medium:
fertile soils are characterised by high numbers of earthworms; these create a good crumb structure in the topsoil so that when it is handled it breaks down into a mass of small crumbs or granules fertile soils tend to have merging boundaries between the different layers in the profile. In contrast, infertile soils have few earthworms, an amorphous structure and tend to be strongly layered.
Soil erosion The information that you have collected on local soil textures will help indicate the potential extent of the wind erosion problem on your site. Soils with fine light particles will blow most easily. Surface wash erosion will be a problem where there is any bare soil; such soil is always likely to be eroded by heavy rain and by the associated surface wash, particularly if the land slopes.
Tipped and toxic material (see also the earlier section on geology) Check if there is any evidence of tipped material on or near your site, or whether old industrial uses might have left a legacy of contaminated soil. Where no records of the content of waste tips are available, either because the tips have not been used for some time or because you are working in a place which has not kept records, it is only close observation of a site which will highlight the problem. Talk to the locals and the older people in particular about their memories of any tipping. Be suspicious - more soil has been contaminated than we realise and should not be used on gardens or allotments. Indicate any areas that you are concerned about clearly on all maps and have a check of the chemical composition carried out when possible. |
Sustainable
Communities - local action
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