The article deals with the problems of landslide influence on the landscape components, landscape transformation under the influence of landsliding processes, singling out the structural parts and elements of landscape and landsliding systems, classification of landscape and landsliding systems. The criteria of feasibility of landscape and landsliding regions are brought; ecological optimization of landsliding landscapes during compliance with ecological monitoring is given.
Keywords: landslide, landsliding process, landsliding landscape, landscape and landsliding system, landscape and landsliding region, ecological optimization.
The urgent problem of ecological landsliding study is a problem of the landsliding landscape. Relief and hydrology particularities of landsliding regions allow to consider the landsliding landscape to be a special ecocomplex, since landsliding free fields, gradually gaining soil-vegetable cover, turn from a geomorphological body into a natural complex. Naturally, landslides differently influence upon the different components of this landscape. Firstly, landslides form a definite morphosculpture. Relief-forming role of landslides reveals itself in the strongest degree in the cumulative zone, where as a result of slope lower parts’ cutting the block landslide motions occur and smaller landslide damages are activated mainly in the river-bed part of the valley [1]. River-bank crushing exists in some areas. In the river-beds of large and small Daghestan rivers the erosion of alluvial and proluvial accumulations and indigenous beds of mountain flows takes place. The breakout of lakes, generated by landslides, and breakout of takeaway lateral cones, blocking the valley have been noted. As a result of a cutting by water flow the block landslides and ancient landslide sediments, mud-streams in tongue parts of modern landslides, small landslides damages along river-beds are activated. In some areas river-bank crushings occur. Sometimes along the river bed the repeated motion of old landsliding masses went down earlier is registered. Landslides greatly influence upon vegetation: they either destroy it on their way or damage it significantly. Specific vegetative associations are formed on landsliding bodies.
Landslides not only influence upon certain elements of the landscape, but also form specific natural-territorial complexes. In our opinion [3], the necessity of the development of the theory of mountain slopes’ stability is ripe. So, beside the study of separate landslide bodies, it is necessary to study the structure of natural complexes and their environment.
The functioning is closely connected with the structure, which occurs under the influence of geosystems of a higher order. Lately we [3] have singled out the three development stages of a landsliding slope: 1) pre-landsliding; 2) landsliding; 3) post-landsliding. They show the direction and the way of changing the slope stability. Each development stage is characterized by processes, with the help of which its functioning is realized.
According to liability to landslide generation it is possible to divide the Daghestan landscapes into interfluvial and valley-river ones. The transformation of their landscapes under the influence of landsliding processes takes place differentially and realized by means of changing the morphological structure, functioning and dynamics [2, 3]. So, the role of landsliding processes between rivers consists in local change of the landscape morphological structure, connected with underground water draining, formation of hydromorphic landscapes.
The transformational process is particularly intensive, up to the damage of morphologic structure of indigenous landscapes and their change into secondary ones. It takes place under the influence of landslide processes, running on steep slopes of river valleys. Most distinctly it is observed in valleys of the Samur, the Kurakh, the Akhtychay, the Usukhchay, the Gyulgerichay rivers. The slope landscape functioning of the river valleys gains the new tones, sharply increases the dynamics of landscape-forming processes.
Landscape-forming role of landslide processes on accumulative terraces is relatively insignificant. Landslide spreading here has an episodic nature. In D.A. Lilienberg’s [5] and I.N. Safronov’s [6] opinion, the landscape morphological structure is basically subjected to change in terrace benches, divided by ravine and gully systems, in the areas of river underminings or reservoir abrasion.
The landsliding landscape formation within flood plains requires the specific conditions: the availability of clays, laying under alluvial thick masses of the flood plains; undermining; excessive moisturizing of flood plains with their deposited soils and meadow and motley vegetation. The landscape re-arrangement, dynamism reinforcement exist on flood plain ledges, where landslides are active [7], but not powerful though, excessively moisturized. They are characterized by simplicity of the landscape structure.
It is important to show the place and the role of landsliding processes in the formation of ravine and gully systems of Southern Daghestan and, in particular, their landscape structure, functioning and dynamics. Undoubtedly, the role of landsliding processes in the formation of slope landscapes of ravine and gully systems is particularly great. As our direct observations have shown, in Shur-dere tract (between the Gyulgerichay and Korchagsu rivers), there are the facts of the structural damage of the erosion relief and landscape as a whole under the influence of lansdsliding processes. In many areas inter-gully spaces has been ruined, instead of them relief forms with mountain remains have been formed, where the landscape forms the typical element of the morphological structure of ravine and gully ecosystems.
Landsliding processes feel the influence of both zonal and regional particularities of Daghestan nature. Zonality of landsliding processes is expressed in their modes, belonging to the certain seasons, arising the number of landsliding types, typical for determined climatic conditions. In the areas, where some deflections from usual typical zonal conditions take place, the more favourable regional conditions for development of landsliding processes have been created.
The regional differentiation of landsliding landscapes are complex, varied and depends on many reasons. Firstly, it depends on the history of the territorial development during the Neocene-Quaternary period, including the modern stage [4]. It allowed following the establishment of lithogenous base for formation of regional landscape-landsliding systems.
In the regions with uniform geological structure the landslides are formed, distinguished by similar morphology and formation mechanism. These landslides can be referred to one and same type or limited number of regional landsliding types. In our opinion [2], it is more correctly to study the regional particularities of landsliding systems within the certain physico-geographical regions of our republic, since they have more or less typical physico-geographical conditions. It is possible to consider the borders of Daghestan physico-geographical regions to be the borders of landscape-landsliding regions. The term landscape-landsliding region should be interpreted as a historically formed, united territory in genetic sense. It has specific features of the nature and human economic activities, stipulated the intensity and the directivity of the development of landsliding processes, revealed in the modern relief and landscape morphological structure [3].
This approach must have an applied nature and serve as a base for planning the anti-landsliding actions with provision for regional environmental particularities.
There are very many landsliding classifications, made by geologists, hydrogeologists, geomorphologists, but there is no any classification of landscape-landsliding systems. On the base of similarity of the reasons for landsliding formation in Daghestan we [3] distinguish the following genetic types of landsliding tracts: a) seismogenous; b) hydrogeologenous; c) hydrogenous; d) climatogenous; e) biogenous; f) polygenous (mixed).
Each genetic type of a landsliding complex consists of a kind of landsliding tracts, singled out on the base of soil-vegetative cover. It is the mostly dynamic and necessary during the landscape-ecological approach for landsliding study. Herewith it is also important to take into account the successional nature of the vegetable cover of landslides.
In Daghestan two classes of landsliding landscapes are singled out distinctly: natural and anthropogenous ones. The latter, in its turn, can be divided into two categories: natural-anthropogenous and properly anthropogenous. Both categories of landscape-landsliding ecosystems are of anthropogenous genesis, but they differ by duration of the influence of anthropogenous factors on them. The landscape of the anthropogenous origin, in the development of which the human interference does not stop, refers to the category of properly anthropogenous landscapes. The landscape created under the influence of human activities and subsequently desolated, develops according the natural laws and can be referred to the natural-anthropogenous category. However, if the landslide is influenced by technical anti-landsliding actions and it turns into a natural and technical system, it should be referred to anthropogenous category.
The variety of natural-anthropogenous landsliding tracts and regularities of their spreading are conditioned by certain kinds of human economic activities, conducted under natural conditions, favourable for landsliding processes.
We offer a classification scheme of Daghestan natural landsliding tracts, which can be also used for distinguishing the varied genetic types of natural-anthropogenous landscape-landsliding systems. Its only difference is the fact, that instead of factors, serving as a main reason for generation of natural landslides, their analogues are used from human activities, for example, earthquakes - vibration, slope washing out – cutting, etc. As a result the following genetic types of natural-anthropogenous landscape-landsliding systems are distinguished:
a) natural-anthropogenous landscape-landsliding systems, caused by slope cutting during the road-building, during the linear erosion, caused by discharge of wasted waters, during the abrasive reservoir activities;
b) natural-anthropogenous landscape-landsliding systems, caused by explosions in quarries, vibratory influence of them, seismic effects in the reservoir zone;
c) natural-anthropogenous landscape-landsliding systems, caused by activation of underground waters at the expense of their renewing by wasted waters from enterprises and houses;
d) natural-anthropogenous landscape-landsliding systems, caused by excessive ground moisturizing during human economic activities;
e) natural-anthropogenous landscape-landsliding systems, caused by the human influence on biochemical processes, running under grounds at the expense of microorganisms’ activization, influencing the mineral composition and rock dispersity;
d) polygenous (mixed).
In spite of the different origins, the processes of the development of natural and natural-anthropogenous landslides are much alike, particularly during the mature stage of their development.
The ecological optimization of landscape-landsliding systems has its own specifics, connected with the aggressiveness of conditioning process and low quality of acultural landscapes, and requires complex, differentiated approach.
As we suppose [3], the ecological optimization of landscape-landsliding systems of the republic must be realized following three directions: regional, typological and paradynamic (paragenetic) under the essential ecological monitoring [8].
The regional way of ecological optimization of landscape-landsliding systems is based on the account of the broad range of landscape-landsliding complexes, connected with certain environmental types, and specifics of the economic exploration of one or another part of the republican territory.
It is reasonable to plan anti-landsliding actions, firstly taking into account the intensity and direction of landsliding processes in different landscape-landsliding regions. This fact will allow to avoid the mistakes and excessive expenses for realization of anti-landsliding measures.
Besides, each landscape-landsliding region has its own criteria of approach for the schedule of anti-landsliding actions. They are absolutely different, for example, in Limestone and Shale Daghestan, or moistened Northwestern foothill and more arid Central foothill regions of the republic. It is promoted by the contrast of the lithogenous base, the moistening rate, intensity of the revealing the landsliding processes, etc.
The regional approach for ecological optimization of landscapes, damaged by landsliding processes, is closely connected with the regional nature management, territorial organization of agricultural production, aimed at revising the land structure with provision for the degree of landsliding danger. Herewith an important thing is an undertaking the cadastre of lands, damaged by landsliding processes, which in official statistical materials refer to the secondary category.
During the typological approach for ecological optimization of landscape-landsliding systems of the republic, we should carefully approach to diagnostics, revealing the main reasons of the landsliding generation, mechanism of their motion. Elimination of the main reason can make all the rest secondary factors fade by itself.
The base of typologic approach for ecological optimization is a classification, according to which the genetic types of natural and natural-anthropogenous landsliding tracts are distinguished with particularities of their morphological structure, functioning and dynamics, but then, depending on this fact, the scheme of anti-landsliding actions is scheduled, amongst which the anti-erosion slope ploughing and phytomelioration are main.
Paradynamic approach is oriented for ecological optimization of landscape-landsliding systems, representing the river basins and ravine and gully systems, landscapes of which have been subjected to the transformation under the influence of landsliding processes during intercoupling with other exogenous processes. During the ecological optimization of ravine and gully systems it is important to take into account not only their variety, degree of the slope stability, but also the stability of their relief structures, landscape as a whole. In this case the object of ecological optimization of landsliding ravine and gully systems is a morphological structure, which under the influence of agro-, wood-, hydromeliorative measures, which take place on reservoirs as a whole, can gain the stable nature. Alongside with it, within one and same ravine and gully system can be the landslides of different genesis, that requires using the different types of anti-landsliding systems.
Consequently, taking into account the regional particularities and classification of landsliding systems, the complexity of their morphological structure, it is necessary to choose the most efficient way of ecological optimization, that does not break a homeostasis, i.e. the mechanism, providing the relative dynamic constancy of the system. The approaches to ecological optimization of natural-anthropogenous landscape-landsliding systems remain the same, as for natural ones, but with provision for their anthropogenous genesis.
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