CHAPTER 1. MODIFICATION OF THE SYSTEMS
Human landscape (*)
(*) related to the LANDSCAPE chapter of FYR Checklist
Landscape is the combination of the visible features of a place, a territory, it is the “view” that we admire (question 1 of Landscape).
Springs, rivers, lakes, streams, marshes give shelter for many environmental processes. The energy of water constantly shapes the land, creates the most varied environments, and provides therefore habitats for a multitude of species. However, all the world estimates state that biodiversity of freshwater is decreasing very quickly; the reason for this phenomenon is that man regularly modifies and destroys freshwater and its habitats: drying of marsh lands, use of flood areas for agriculture, canalisations and river diversions. (questions 2-3-5-6-9).
Man has always changed the environment to make it suitable for his settlements and to produce the necessary natural resources for the community. Therefore, the analysis of a watershed looks at the history of its environment as well as the history of the people who have settled there. It shows the way, the reason why, and the place where cities have first developed and it explains the choice of many industries to settle at typical locations within a watersheds in order to exploit hydroelectricity or other resources present.
Regulation and other works on rivers (*)
(*) related to the subchapters 4 (urbanisation), 8 (protection), 9 (restoration) of the HUMAN USAGE chapter in the FYR Checklist
Man-made works, which are constructed on rivers (e.g. embankments) even today, are aimed at “controlling” rivers to enable the exploitation of the land around them for agriculture, housing and industry as well as for flood prevention.
Embanking, which is used to manage and exploit the waters of the rivers (question 4 a-b HUMAN USAGE), alters the natural morphology of the river and the outflow of the waters and increases the vulnerability of the whole system. The large artificial hollows and the transversal works alter the transport of solid materials and influence the methods of deposition; the basin is progressively covered with sediments, which are blocked by the barrage that disrupts their flow, while the water and the soil in the valley, without replenishment, are then impoverished of needed minerals and top. This can in turn lead to accelerated erosion. Barriers also obstruct the fish passage (question 4c) and the water regulation trough barrages such as dams or locks causes variations of water level, which consequently can destroy entire populations of nesting birds.
Dams, which are barrages that create huge hollows from high water flows to hydroelectric power plantsthrough conduits, cause the worst damage on rivers and their surrounding regions. Worldwide, huge manmade works are built and the diversion of entire watersheds modifies the landscape and the involved surrounding ecosystems irreversibly.
A new sensibility for river protection is fortunately appearing (question 4d), for example, in restoration works (subchapters 8/9 all questions) which aims at restoring the “natural” environment of the rivers as far as possible, and consequently their most important ecological functions:
- capacity of self-purification, with the subsequent reduction and prevention of pollution;
- capacity of floods control and reduction of hydrologic risk
- environmental rehabilitation, through the restoration of the ecological continuity of the course of the river.
However, it should be kept in mind that these are complex processes, and it will take years for the entire river ecosystem to regain its balance.