The evident, economy and constructions influencing phenomena of natural environment , such as relief, hydrography and climate, characteristically occur in settlements. The effect of these phenomena may be direct or indirect, which have to be taken into consideration at settlement designing. The effect of diversiform and divergent dimensional surface forms most of the time is indirect, that is they prevail merely through the climatic, or rather hydrologic processes that they have influenced earlier. (LOVÁSZ 1982)
One group of direct impacts - that may be linked to relief - is of urban aesthetic, psychological and health character. The slopes and roof surfaces of ridge of hills and ridge of mountains and foot of the mountain stairs or rather the establishment that have been built there has a great role in settlementscape (settlement picture) formation. Slightly sloping plateaus which rise above their environment constitute part of the positive
―formtreasure‖ (landforms). They usually lie far from noisy city centres, since they are relatively lately incorporated in the course of settlement expansion. These positive morphological forms possess own sanitary function. In our bigger towns on windless autumnal and winter days, unpleasant smog and fog of slightly some ten metres thickness above the surface are frequent. (at Pécs, for instance) Smog and fog relevantly rarely occur in mountain ridges and crasts that rise over sole of valleys. The more the relative height difference is, the most favourable the situation is. From this aspect, these forms may be preferred in the positioning of such establishments and institutions, in the cases of which smog and fog exemption and the autumnal-winter sunshine-abundance are extremely important.
Steeper slopes which belts ridges of hills, nevertheless may have negative impacts as well, namely in the case of specific geological construction they move or in milder cases they are slide-dangerous (eg. Miskolc- Avas, Dunaszakcső, High shore.) This natural process in more cases is a delimiting and a cost- increasing coefficient
from technical aspect. In the latest years it has become fashionable in our cities to build in mountain side with city views and hereby taking the additional costs and risks.
Valleys of dissimilar width and cross-section represent negative relief forms. Complex natural-environmental facilities that is forming in them, in many respect are more favourable than the opportunities of steeper hillsides or slopesides, however in many cases they rather localize town settling opportunities. Wide, bowl-shaped valleys represent the typical areas of the smog or fog formation that has been repeatedly mentioned earlier.
These adverse effects only lessen if there is a mountain hereabouts and the wind starting from that mountain sweeps out the ‗tired‘ air masses. Furthermore these are the water-catchment of surrounding higher areas, thus the sole of the valley is often waterlogged, morass, moreover in some cases they carry themselves the risk of floods or flash-floods. (Miskolc, Eger, Pécs, or in the flat landscape: Szeged ) (Figure 3.3.)
Unfortunately the recognition of the problem has not pursued by suitable defensive intervention up to the present day, thus in the lack of proper protective works (establishments) they build on flood risk territories. ( e.g. Miskolc, Ipolytarnóc.)
Figure 3.3. Lightning Flood of Tardona stream in Kazincbarcika in spring, 2010 (own image)
Lightning Flood (own video)
There is a high-risk of watering up of buildings in the lowest points of the settlements, which can only be solved at excessive costs. In some settlements, after the filling of wetland, stakes were beaten in the ground to built there (for example: Eger-Líceum). Areas with high soil water (inland waters) have a different, unhealthy microclimate, its residential function is limited, these areas are only suitable for industrial facilities. In case of wide valleys, it can often be observed that larger valley marginal band, which is the most suitable area for construction, is without the negative side effects of the valley bottoms and the steep slopes.
In lowland areas, the above described positive and negative macro land form naturally does not validate its effects. In contrast, the influence of micro-topography characterized by only a few meter differences above sea level and hydrological conditions are amplified. People living along the rivers throughout history knew exactly that wetlands are only for grazing, higher lying areas are for arable farming and non-flood areas are for
permanent establishment. In nature, all topographical forms are separated from each other with slopes. Their review is essential in terms of inclination, orientation, length and shape analysis in terms of urban development.
This should be considered along with valley networks and geological conditions during installations or during the design of road reconstructions. Closing road networks to the run of contour lines can greatly reduce the burden of cars, buses, etc., and thus reduce noise, vibration and air pollution of the settlement (TÓTH 1981).
Beside the obvious negative effects on the natural environment it should be noted that the vulnerability of society - the installation of less favored areas , and with the development of infrastructure - is gradually increasing towards earthquakes as well. This is especially true in large cities such as Budapest, Eger and Kecskemét (Figure 3.4.). With earthquake-resistant design and proper preparation the risk can be reduced. The seismicity of Hungary is moderate, earthquakes causing less damaging generate approximately every 20 years, earthquakes causing significant damage (magnitude 5-6) generate approximately every 50 years. The last major (M = 4.9) earthquake was generated 25 years ago in 1985 in Berhida.
Figure 3.4. The country's third largest earthquake was in Kecskemét in 1911 (www.kecskemet.hu)
People only recently started to take note of the naturally occurring harmful quantities of radon isotopes, exceeding the limit dose with more than ten thousand fold. Radon gas is an intangible, invisible, but very high-risk carrier geographic phenomena. The primary source of high radon concentration, formulating in buildings, is the soil. Radon is flowing from the upper 0,8-3 m – if the soil is homogeneous – into the pore space, depending on the permeability of soil. In extreme cases, for example along the fault lines it rises from the deep (eg.: Eger).
If the rock contains high levels of Ra-226, radon is also expected to be high. Therefore in several countries, before construction works begin, the soil is classified, depending on the results they prescribe the required protective methods (eg.: radon barrier). But the most basic protection that can be used in every building, without investment in almost all geographical conditions, at any time is natural ventilation. (MOSER–PÁLMAI 1992, FÖRSTNER 1993).
Figure 3.5. Possibilities of radon entering a building (own work)
radon updraft
bedrock; soil overload; Sources; well; soil gas; cracks, fractures in the bedrock; updraft; channel;
shower; trap; windows; crack; components; foundation; plinth; catchment; mine;
Under mining can be a threat in urban areas. In underground abandoned mining flights the faliure of filling, or the technical limitations of the filling can also convert the surface, causing uneven subsidence. The problem is complicated by the absence of accurate maps of mines from the XIX. century, so we have no information about the underground world rearranged by flooding and firedamp explosions and it can not be ruled out that some private owners are not venture out beyond their approved mining site for more profit (for example in Tatabánya or Egercsehi.). For example, the VI. site church in Tatabánya sank 1.7 m due to under mining. As the aftermath of mining typical examples for subsidence is: the Borsod mining district, especially Bükklába. The underground mining activities created a major even up to 4m deep subsidence, putting all surface investment, infrastructure development at risk (Figure 3.6.).