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GEOMRPHOLOGIC EFFECTS OF ROAD NETWORK

Dctailcd rcscarch showed that road nctwork dcnsity has not changcd significantly for about 150 ycars. What has altcrcd grcatly is thc road distribution - only 50% of thc prcscnt roads arc oldcr than 150 ycars.

The communication system rearrangement was caused mainly by main routes_replacc-ment from tophills to vallcys and took place in the 19 century.

Today thc remains of old, abandoned roads arc prcscrvcd as a cuts. Thcsc cuts can bc divided into two elasses: main routes leading along tophills and roads that joincd thosc main routes with inhabited valleys.

The road cutting speed is strictly rclatcd to thc land usc intensity. According to one of thc oldest sources, dating the 16 century, main roads at that timc led in dccp cuts. This fact was confirmcd by the rcsult of prccisc rcscarch on the historical maps.

Concluding: until thc half of 19 century main routes wcrc conducted through concave forms. Today sccondary roads, which are older than 150 ycars and led only to plots, arc 1 m dccp at maximum (apart from soil formations). Only a few sccondary road gullics rcach thc depth of 4 m. This arc fragments of old roads which wcrc main routes uscd sińce 16 century.

Evolution of thc road cuts docs not stop with road rclinquishmcnt. Its coursc is defined by thc slopc from which a particular road collccts rainfall. Somc roads, that collcct water from surfacc runoff, transform their cross-scctions to v-shapcd and can bc cut to 2 meters dccp maximum. Roads that do not participatc in conducting rainfall accumulatc materiał from their walls and surroundings.

HYDROLOGIC EFFECTS OF ROAD NETWORK

One of thc first aspeets of hydrologie anthropopression was road location in thc natural cnvironmcnt. Road influence is mainly confirmcd by two facts: roads altcr natural flow lines on thc slopcs and they divide catchments into smali basie, independent arcas. What is morc catchmcnt fragmentation causcs initial streams cmcrsions and thcrcforc watershed contrac-tion.

In Zalasowka catchmcnt 75% of streams arc thc initial ones. In that terrain initial watershed arca for one stream shrinkcd from 0,8 km² (calculatcd for catchmcnt with no road nctwork) to 0,4 km² (calculatcd for catchmcnt covcrcd with factual road nctwork).

Bccausc thc number of initial flows is growing thc probability to conncct to another stream is higher. This is a rcason for crucial hydrologie cfTects such as:

incrcascd number of high order streams,

rcduccd medium distancc to a stream, thercforc quickcr rainfall transfer, highly cfficient catchmcnt drainage system.

Roads arc charactcrizcd by straightforward coursc and Iow surfacc roughncss. Both fac-tors accclcratc water outflow. 1/3 of Zalasowka catchmcnt is draincd through roads.

Road nctwork on Cięzkowickic Foothills is so dense, that it modifies Horton order ratios, which arc an csscntial componcnt of thc runoff modcls. The dcgrcc of this modification shows thc anthropogcnic intcrfcrcncc in natural outflow from catchmcnt.

The rcsults obtaincd from dctailcd rcscarchcs wcrc uscd to simulatc thc unit hydrograph from thc Zalasowka catchmcnt. Two modcls wcrc built on thc basis of thc gcomorphic instan-