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Geomorphology & Environmental Impact Assessment​

by Mario Panizza

· Geomorphology,Environmental Impact,Assessment
Professor Mario Panizza PhD


When a project is undertaken there are several effects on the environment in which it is inserted. These effects can be of various types: quantitative and qualitative, direct or indirect, short or long-term, permanent or temporary, single or cumulative, positive or negative, etc., and include also those that can occur during the construction and decommissioning phases (see Wathern ed., 1988).

Seldom have these environmental problems been a condition or a part of planning. Indeed, the aim of the impact procedures is to ascertain beforehand, by means of analytical approaches, whether the changes brought about in the environment permit the re-estabilshing of an acceptable balance in the use of environmental resources both for the defence of public health and people's living conditions. The feasibility of a project can be assessed on the basis of the results of these studies, in relation to the impact foreseen on the environment and the identification of risk levels. If the result is negative, studies will have to show the modifications which will have to be made to the enterprise so that it can be compatible with the environment, or possible alternatives that could reduce its negative effects. The importance of a precautionary evaluation of a project's consequences, has led to the definition of systematic and integrated procedures based on various technical, administrative, scientific, social, etc., parameters.

Environmental Impact Assessment (EIA) is a procedure for assessing the environmental implication of a decision to implement policies, plans, programmes and projects. Thus, the scope of an EIA system could encompass all these undertakings at all levels of government. Lee & Wood (1978) have suggested a tiered comprehensive system applied to a sequence of action categories and administrative levels (Fig. 97). However, the vast majority of environmental impact statements in different countries have been related to projects.

The first country that officially introduced the procedure of impact evaluation was the United States of America: in 1969 a law (NEPA = ''National Environmental Policy Act") established the principles of environmental policy in that country. It introduced a series of norms for the preventive evaluation of impacts: the ''Environmental Impact Statement" (Council of Environmental Quality, 1973). Afterwards, other countries, in particular France, the United Kingdom, Canada and Australia, adopted similar procedures.

Fig. 97. Categories of action and levels of government within a comprehensive EIA system (after Lee & Wood, 1978, modified).

On 27 June 1985 also the European Community acknowledged this need and adopted a Directive making environmental assessments mandatory for certain categories of projects. This Directive is applied to projects that owing to their nature, size and location can determine a considerable impact on the environment. Two kinds of project categories should be taken into account in this evaluation: those that in any case produce serious effects on the environment and therefore necessarily imply an Environmental Impact Assessment (EIA); those that may have serious environmental consequences according to circumstances: for the latter category the compulsoriness of the EIA will have to be established for each individual case.

As regards the impact studies, it is necessary to identify those environmental components which are not only particularly significant to the environment itself but also sensitive to the work that is going to be carried out in a certain territory; these are named environmental indicators. They are employed both in the description and interpretation of the environment, in the planning of the location of a certain project and within the radius of influence of the project itself, as well as in the impact identification and evaluation phase, concerning the influence produced on the indicators.

For identifying and assessing impacts, surveying and monitoring systems are used which refer to environmental indicators and transfer the data into adequate control lists or cause effect matrices (see Leopold et al., 1971).

Here it is not the case to go deeply into the complex general themes of EIA, regarding which the reader is referred to the above mentioned authors and their relative references, but in the following chapters the problems concerning Geomorphology more specifically will be dealt with. Also the conceptual and methodological bases used for some research of an European Union contract' (see Marchetti et al., 1995; and more in particular: Bollettinari, 1995; Panizza, 1995; Rivas et al., 1995; see also the final publication: Panizza et al., 1996) will be illustrated.


First of all, research must be carried out to identify the three main groups of geomorphological components, which may be treated differently (see Panizza, 1995): processes, landforms and raw materials (Fig. 98).

Fig 98. Conceptual basis of the relationships between two of the geomorphological components (landforms and processes) and a project.

Figures 99 and 100 show in synthesis the conceptual bases of the simplified relationships between the above mentioned geomorphological components and the project.

In particular, the processes which when hazardous are geomorphological hazards, may interfere with a project, which is always characterised by specific vulnerability and cost (Fig. 99). The activity of these geomorphological processes may produce damage for the project, that is to say a risk for the project. This is the case of a landslide (geomorphological hazard) which may damage a motorway (project). In this situation the natural component of the environment shows an active role and the project a passive role.

Furthermore, particular landforms which if valuable are geomorphological assets, characterised by specific fragility and value, may be affected by a project (Fig. 99). The effects on geomorphological assets deriving from the implementation of a project make up a direct impact, which causes environmental damage for the same assets. This happens, for example, when the construction of a road ruins a glacial cirque. In this case the natural component of the environment has a passive role with respect to the project which plays an active role itself.

Nevertheless, it should always be remembered that there are some processes that can be considered as beneficial (e.g., a particular kind of erosion which may be considered as an educational example). However, these processes produce a landform and then can be included in it.

The same considerations can be made for particular raw materials which if valuable constitute geomorphological assets: the interferences with a project may produce a risk or a direct impact (Fig. 100).

Fig 99. Conceptual basis of the relationships between two of the geomorphological components (raw materials and processes) and a project.

Fig. 100. Types of thematic maps for Geomorphology and EIA studies.

Also in this case there are some materials that can be considered as hazards (e.g., salty soils meta-stable sands). However, these materials are the result of particular processes and therefore can be included in the latter.


Research should be carried out following the scheme below (Panizza, 1995).

  1. Types of Projects.
  2. Investigation phases.
  3. Mapping.
  4. Indicators.
  5. Evaluation of Hazards and Assets.
  6. Evaluation of Impacts l.s.
  7. GIS Methods.

ad. 1. Types of Projects

The norms of the European Union for EIA's studies cover essentially the following types of projects of the 1st category, here subdivided into groups with analogous characteristics for geomorphological research:

  1. refineries; chemical plants, plants for coal aeration, asbestos mining processes, etc.; thermic and nuclear power plants;
  2. radioactive and toxic waste plants;
  3. transport infrastructures (motorways, railways) and airports;
  4. commercial harbours and navigation lines.

Owing to the connections with Geomorphology, also the following projects from the second category can be taken into account:

  1. tourism infrastructures;
  2. land use change;
  3. mining activities.

ad. 2. Investigation phases

The investigation phases can be defined as follows, with progressive increases of

Detail and scale.

There are moreover three steps normally followed for the development of a project:

  1. design;
  2. operation:— construction; — functioning; and
  3. decommissioning.

EIA investigations should be carried out in Phases I and II so that the results can be included in the detailed planning and design of the project (Phase III). This planning phase should include proposals of monitoring during construction and recommendations for mitigation measurements to be included.

As construction proceeds, more information will become available, particularly about the materials and the subsurface conditions.

Also a failure of the design may occur.

In carrying out diagnosis and remedial measures it may be necessary to modify the predicted EIA. The procedures to be followed will, however, be the same.

During the functioning operation it is recommended that the degree of success of the predictions and impacts is evaluated as a guide to maintenance routines and future design practice. In the decommissioning operation it will be necessary to design a new EIA, in order to predict the effects of the abandonment or dismantling of the plant (e.g., pollution, uncontrolled mine drainage, etc.).

ad. 3. Mapping

The types of thematic maps used for these EIA studies are summarised in Fig. 101. They are both base maps and derived maps, to be used at different scales according to the investigation phases: for example a small or medium scale map for phase I, a detailed one for phases II or III.

Fig. 101. Conceptual and methodological scheme of the role of Geomorphology (landforms and processes) for the EIA and a project.

As for thematic base mapping, it is possible to make reference to various geo- morphological, geotechnical and hydrogeological maps, well-known in literature. As for thematic derived mapping it is possible to make reference to some examples of stability and hazard maps made by some groups of researchers; however, examples of thematic maps concerning geomorphological assets are rarer. The derived thematic maps can be integrated with data from literature, archives, databases, etc. During investigation phase I more general maps like morphometric and morphographic maps can be used.


For example, with respect to the hazard maps (concerning geomorphological processes) references may be made to the contents of chapter 3.9. On the other hand, as regards mapping of geomorphological assets, reference should be made to the contents of chapter 2.3.

ad. 4. Indicators

In the specific literature various definitions of the term indicator have been given since this word may be applied to all the variety of environmental aspects, ranging from geological indicators to urban ones, to quote just two. Although varying considerably from one author to another, involved in Environmental Impact Assessment, all the definitions of this term show the need to emphasize in a significant and summarised way an environmental phenomenon. In the specific case, a geomorphological indicator should describe a situation, a geomorphological process and, according to the situations, also its evolutive trend and its susceptibility to an external intervention. Therefore appropriate indicators should be selected for each assessment investigation in order to acquire an exhaustive but concrete picture of the specific situation; at the same time, all those not strictly necessary should be omitted, in order to avoid accumulating an excessive burden of data which would make the work unmanageable from an economic point of view.


Impact is expressed by the changes affecting an environmental unit following the implementation of a project. These changes will be emphasised just by the indicators which depend both on the environment and on the project.


Example. Let us consider an arenaceous slope subject to natural erosion producing sandy debris. The detritus accumulates in a riverbed at the bottom of a slope and is subsequently carried as far as the sea and deposited along the coast. It is obvious then that any human intervention on the slope will alter the pre-existing equilibrium. In fact, if the slope is totally or partially covered with concrete (project), erosion will either stop or decrease and therefore the production of detritus will tend to zero. As a consequence, the river will no longer receive the input of material that determined its pristine balance and the energy previously dissipated in the load and transport of the sandy sediments will be mainly directed to fluvial erosion activities. Supposing the riverbed is made up of clayey rocks, the material removed will no longer contribute to the replenishment of the pre-existing beaches, contrary to what happened when the transported material was made up of sand. Consequently the beaches, thus deprived of adequate solid supply, will retreat. This example is shown just to quote some of the processes that take place when the slope conditions undergo changes. Also other processes could occur, such as interference with the groundwater or undercutting at the slope toe. In such a case the process indicators to be found are: one in the fluvial system and the other in the coastal one.


In order to evaluate indicators for hazards and assets, it is important to consider the scale and the density' of particular hazard processes and/or geomorphological assets. The lifetime of the project must be considered in order to evaluate the hazardous processes which can be at risk for the project or can be induced by the project. It is therefore necessary to prepare a list of indicators for hazards and assets. From this point of view, the frequency of the processes must be evaluated and compared with the lifetime of the project.


According to the main groups of geomorphological components, the investigation phases and the scale of investigation, the indicators will be subdivided into three groups:


A. Morphometric and morphographic.

B. Hazards.

C. Resources.

ad. 5. Evaluation of Hazards and Assets

The evaluation of hazards should be developed using different methods:

  1. Direct measures (e.g., on scarp retreat).
  2. Mechanical models and calculations (e.g., geotechnical measurements).
  3. Crossing of ''causes" (e.g., overlapping thematic maps).
  4. Statistical approach of ''effects'' (e.g., recurrence of landslides).

The first method consists of direct measures of some indicators. In the case of an active cliff the measure of the risk for a project on the top of the cliff itself, may be represented by the direct measure of the retreat of the slope or the variation in the slope angle, etc.


The second method is developed using geotechnical measures and engineering models. For example in the cliff case geotechnical parameters and engineering models may be used in order to evaluate the retrogradation of the cliff.


The third method takes advantage from the crossing of different thematic maps in which the indicators are considered. For example, in the case of the above mentioned chff the evaluation should be estimate by the overlapping of different maps such as lithological, morphometric, vegetational, etc.


The fourth method requires a good knowledge of many parameters in a large area. On the basis of statistical behaviour a forecasting of hazardous events can be evaluated. For example, in the cliff case, the retreat of the slope can be predicted on the basis of the general retreat along all the coast.


The evaluation of assets is described in 2.3.


The hazards and assets will be related to the following groups of morphogenetic units:

  1. Weathering.
  2. Slope:
    • soil erosion/sedimentation; and
    • mass movements.
  3. Periglacial (including special mass movements).
  4. Glacial.
  5. Fluvial.
  6. Coastal.
  7. Aeolian.
  8. Karst.
  9. Subsidence.
  10. Groundwater.

ad. 6. Evaluation of Impacts

Starting from Figs. 98 and 99 it is possible to indicate a conceptual and methodo- logical scheme of the role of Geomorphology for the EIA of a project, with the specification on how the active and passive elements combine in giving different types of impact is. (broadly speaking) (Cavallin et al., 1994).


Figure 102 takes into account the geomorphological components landforms and processes. Beside the consequences in terms of risk and direct impact shown in section 6.2, a project during its implementation, functioning and decommissioning, may produce induced hazards, i.e., hazards which did not exist in the area before the introduction of the project. These induced hazards may give rise to three kinds of induced direct and/or indirect effects: direct risk, indirect risk and indirect impact

(Fig. 102).


Direct risk can be delineated as the effect on the project of a hazard induced by

the project to itself; in this case a reflexive action takes place. For example, the construction of a road may cause the instability of the slope where this road is built, thus endangering the project.


Indirect risk consists in a hazard induced by a project which damages the surrounding settlements. This is the case of a landslide induced by a road cut, which endangers a village located in the vicinity of the project.

Fig. 102. Conceptual and methodological scheme of the role of Geomorphology (landforms and processes) for the EIA and a project.

Finally, indirect impact refers to the effects of hazards induced by a project on geomorphological assets existing in areas surrounding the same project. For example, the filling of a lake, which is considered a geomorphological asset, due to a landslide triggered by the construction of a road.

The same considerations can be made by taking into account the geomorpho- logical components processes and raw materials.

For the evaluation of the different types of impact l.s. mentioned above, for each type of project (ad.1) and for each investigation phase (ad .2), the main research instruments are the maps (ad. 3) and the indicators (ad. 4).

ad. 7. GIS techniques

Geomorphologists have long recognised the importance of morphometric studies. The availability of altitude data in digital format, and the possibility of preparing and analysing Digital Terrain Models (DTM) may be important tools for quantitatively analysing topographic elements (see Pike, 1993). Software packages specifically designed to produce high fidelity DTM are now available (e.g., Carla et al., 1987; Carrara, 1988) and to produce derivative maps such as slope, aspect and so on.

The principal aim is to design and apply a structured method for EIA studies in the field of geomorphology, including data collection, updating, modelling and analysis, using GIS techniques to automate and optimise the decision-making processes.

Part of the required parameters for an evaluation of the impact on assets consists of subjective analytical expertise, weight setting, application of nonspatial indices, etc., that cannot be applied directly in a GIS. Nevertheless, some of the criteria need a spatial definition a priori, such as all phenomena occurring in the study area or in the area of influence where GIS applications can be partially or completely included. In most cases, though, it becomes evident that a GIS represents a convenient tool for interpreting the data necessary for the assessment in terms of feasibility analysis, robustness of the impact measurements, sensitivity and comparability analysis with spatially referenced information. Much work is still required, however, to bring spatial data analysis, geomorphology and EIA into the realm of routine procedures using widely accepted and significant standards (Patrono, Fabbri & Veldkamp, 1996).

Quantification of impact*

*in collaboration with Mauro MARCHETTI

1. Raw Materials

The methodology proposed by Rivas et al. (1995) is presented below. It has been used in the already cited Human Capital and Mobility Contract.


The types of direct impact on geomorphological raw materials which can take place as a result of different activities are:


— consumption as a consequence of direct extraction;

— sterilisation as a result of activities which make the resource unusable;

— permanent sterilisation;

— temporal sterilisation; and

— degradation due to pollution which can alter the properties of the material.


In order to quantify the impact on existing raw materials in a given area, the following parameters have to be considered:

The direct impact on raw materials (Ir) can be expressed as a potential monetary loss by means of the following expression:

The total direct impact on raw materials (ITr) would be:

where n is the number of outcrops.

2. Landforms

Here an investigation methodology set up and applied in the already quoted Human Capital and Mobility Contract research is illustrated. It represents a synthesis of some methodological proposals and a combination into a minimum approach to assess Quality and Impact on geomorphological landforms after a project (Marchetti, Panizza and Patrono, 1996).

In order to evaluate the direct impact on landforms, it is necessary to assess the quality of each of them. Here only the scientific attribute, as defined in paragraph 2.2, will be considered, since it is peculiar to Geomorphology.

The scientific quality of each landform (Q) can be considered as depending on two main characteristics: intrinsic scientific value (V) and degree of presentation (C). These may be related as follows:

Q = V * C

Intrinsic scientific value can be defined from the geomorphological standpoint as:

where G, O, P and E are the characters of the landform (see § 2.2) and in particular:

G = model of geomorphological evolution;

O = object used for educational purposes;

P = paleogeomorphological example;

E = - ecological support.

In the last equation they are (usually) equal to 1, unless one of them is put in evidence (then >1) or, on the contrary, is disregarded (then <1).

Lg, Lo, Lp and Le are the levels of interest of the landform (considering here its rarity) (see § 2.2) and particularly the following weights:

The condition of preservation (C) of a landform is connected to its conditions at the survey moment and can be quantified as 0 < C ≤ 1 (1 = well-preserved).

For the assessment of the direct impact the procedure is as follows:

The degree of damage (D) to a landform can be calculated as a consequence of the implementation of a project. Due to the possible variations from case to case, is is better to consider its value in a continuous range: 0 ≤ D ≤ 1.

As a suggestion, for the example that follows: 1 = no damage, well-preserved; 0.75 = some deterioration with loss of some minor elements; 0.5 = degraded owing to some human activities which hide part of the features; 0.25 = several human activities which deteriorated the characteristics of the landform; 0 = characteristics of the landform destroyed.

The direct impact on a landform (I1) can be expressed in terms of reduction of scientific quality, as:

Il = Q - Q * D = Q * (l - D)

and if normalised:

The deterioration is compared to the quality of the most representative or ideal situation found in the area. The total direct impact on landscape (IT1) can be calculated as:

where n is the number of landforms considered as geomorphological assets in the studied area and QMax = Max {Q1,..., Qn}.

The indices of impacts here presented consider the impacts as a loss in terms of quality; in particular the closer to 1 are Il and ITl the greater is the damage to the landforms themselves.

Other relevant parameters to be taken into account are visibility and reversibility, which are, in the case of landscape, directly related to mitigation procedures.

3. Processes

A methodology proposed by Bollettinari (1995) and applied in the already quoted Human Capital and Mobility Contract is here illustrated.

This methodology is founded on the principles which were presented in paragraph 3.9 and is used for the assessment and mapping of the geomorphological hazards. According to this methodology, each unstable area is catalogued and accompanied by a detailed list of the processes in action and/or the causes favouring instability.

Significant parameters for the quantitative evaluation of hazard, or the environ- mental components which cause instability, should be established for all the territory affected by the project.

The factors favouring environmental degradation (F) are the lithological, hydrological and climatic conditions as well as the indicators related to possible processes taking place in the study area (I).

Whereas the former offer on the whole a picture of the actual or potential causes of instability, the latter show the effective processes in action at the moment of investigation.

Each parameter chosen is considered separately from the others and quantitatively assessed through the attribution of a weight for each unstable area thus identified during the first phase of the research.

The weight is attributed by the operator on the basis of the knowledge acquired during field investigations, with reference to previously fixed standard values.

The sum of the scores attributed to each parameter (F and I) gives for each area the assessment of hazard (Vp).

F1 + F2 + … +Fn + I1 + I2 + … + In =Vpx

(for area x).


On the other hand, the sum of the hazard's values obtained for each area gives

an appraisal of the global hazard for the territory examined (VpTOT) before the accomplishment of the project.

Vpx + Vpy + … + Vpz = VpTOT

The same procedure for the attribution of weights to each parameter chosen must be repeated with reference to the hypothetical situation which would be determined after the completion of the project.

The value thus obtained (V'pTOT) provides information on the hazard conditions

affecting the territory investigated following the accomplishment of the works (or gives information on territory instability after the project has been carried out. It should always be kept in mind that a V'pTOT value greater than VpTOT shows a worsening of stability and therefore emphasizes the presence of impacts).

The difference between the value (V'pTOT) obtained from the evaluation of the global hazard after the implementation of the project and the one calculated in the real situation (that is before the execution of the works) gives the quantitative measurement of the modifications induced in the geomorphological environment, that is the induced hazard (see § 6.3):

H = V'pTOT - VpTOT

A further stage of the research implies that the impact value should be again recalculated taking into account the hypothetical final situation existing after the accomplishment of possible mitigation measures capable of eliminating or mitigating the recognised impacts. Hazard (V'pTOT) will have to be recalculated in these hypothetical final conditions using the above described method. Finally, from the difference between the hazard after the accomplishment of mitigation measures and the hazard assessed after the implementation of the project, the value of residual induced hazard will be obtained:

Hr = V''pTOT - V'pTOT

The data thus obtained are summarised in a specific thematic map which can be easily consulted even in subsequent phases of the project.

Panizza, Mario., 1996., Environmental Geomorphology., p. 223., Elsevier Science B.V., Netherland

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