Assessment of environmental impact of road construction based on results of remote sensing monitoring

. Remote sensing detected the impact of road construction on important environmental properties. The digital elevation model was applied to assess the impact of road construction on environmental regimes. The study focused on the total area of the 3-km zone of influence (monitoring zone of probable impact) around the national road H-31 Dnipro-Tsarychanka-Kobeliaky-Reshetylivka from Loboikivka village to the boundary of Dnipropetrovsk Oblast. The following derivatives of the digital elevation model are considered as geomorpho-logical variables: the topographic wetness index (TWI) and erosion factor (LS). To model the effect of road construction on the moisture regime and dynamics of erosion processes, the TWI and LS indices were calculated for a digital terrain model without a road and with a road with an elevation that corresponds to the planned level. Thus, the road is considered as an anthropogenic landform that changes the direction of water redistribution along the topography and thus affects the potential moisture conditions and erosion risks. The modeling results indicate that the transformation of the water regime will be observed within the entire 3-km monitoring area. Deviations from the normal value can be up to 7 units by module, which is about one third of the landscape-wide range of topographic moisture index values. Almost no impact of construction can be predicted for 80.7% of the territory. For 10.6% of the territory, the increase in moisture regime will be moderate, and for 3.2% of the area the increase will be very significant. In turn, for 4.3% of the area the decrease in humidification will be moderate, and for 1.2% the decrease will be very significant. The greatest impact on the redistribution of moisture conditions is predicted in the immediate vicinity of the road. Changes in the moisture regime can have significant negative consequences for both soil cover and biotic components of ecosystems. Changes in vegetation as a consequence of changes in both moisture and trophic conditions can be considered as possible scenarios for the development of landscape cover dynamics.


Introduction
The loss of biodiversity is an urgent problem of our time (Naeem et al., 1994;Dornelas et al., 2013), which draws close attention of both specialists and the general public (Zolyomi, 2022).One of the main factors affecting biodiversity is the transformation of ecosystems under the influence of anthropogenic activities (Ellis, 2015).However, there are practically no scientifically based protocols for audit, monitoring, and environmental assessment of biodiversity in the context of studying the impact of various types of economic activity on it.Environmental Impact Assessment (EIA) is a series of scientific and practical actions to collect information on the impact of planned operations on the environment and develop measures to avoid negative impacts on nature (Wale & Yalew, 2010).Environmental impact assessment is legislated in many countries, but there is a widespread challenge that in practice a lot of the process elements are carried out on a non-standard basis (Nita, 2019).Both scientists and practitioners point out the lack of efficiency of EIA measures, which is primarily due to the complexity of translating biodiversity assessments into meaningful management solutions (Wale & Yalew, 2010;Yorkina et al., 2019).Biodiversity evaluation and monitoring protocols should consist of a series of guidelines that apply valid techniques to record living organisms in a spatial and temporal perspective.The report emphasises that without 'scientific rigour', the data collected cannot be meaningful for decision-making and is a waste of time and money (Dias et al., 2017;Zhukov et al., 2019).Assessment using EIA is significant, but the findings may be refuted due to procedural constraints, particularly in terms of biodiversity screening and conservation planning.Ecological niche modelling was proven to be a valuable tool for planning biodiversity-protection activities in the context of hydropower projects (Adhikari et al., 2019).
Incorporating the concept of ecosystem services can improve the effectiveness of the EIA procedure (Ochoa & Urbina-Cardona, 2017), as it demonstrates the performance of ecosystems, which is a key prerequisite for the socioeconomic wellbeing of the population (Zhukov et al., 2018;Sousa et al., 2020).A special focus is placed on the loss and degradation of habitats as a result of project implementation as the primary reason for biodiversity decline.At the same time, the extent and degree of granularity of biodiversity screening is questioned as insufficient for informed decision-making.The major weaknesses are the mismatch between the scale of environmental impact and biodiversity estimates, and the inadequacy of evaluations of anthropogenic pressure and impact on widespread species (Bigard et al., 2017).
Assessment of impact of economic activities on biodiversity should take into account a set of issues (Kunakh et al., 2018), first of all, the main sources of biodiversity decline, namely: 1) habitat loss or fragmentation (Levin et al., 2009;Rytwinski & Fahrig, 2012); 2) overexploitation and irrational use of natural resources (Holmlund & Hammer, 1999); 3) pollution (Jones & Leather, 2012); 4) invasive alien species (Rendeková et al., 2018); 5) climate change (Estrella et al., 2007).Another important issue that is closely related to biodiversity is ecosystem services (Fehrenbach et al., 2015;Mariani et al., 2016;Trivedi et al., 2018).Biodiversity is a condition for the maintenance of ecosystem functions, so the context of biodiversity consideration should be determined by a comprehensive reflection of dynamics of ecosystem services (Zhukov et al., 2021).Thus, procedures and protocols for quantitative assessment and monitoring of biodiversity, along with the conservation of rare species and habitats of different conservation status, should be aimed at identifying markers that reflect the state of ecosystem services (Alasmary et al., 2020).Assessment of environmental impact is a standard procedure in civilized countries, which is a necessary stage of approval of planned activities related to use of natural resources.In Ukraine, this relevant procedure was launched in 2017 and has already shown its effectiveness.However, the practive of applying this law revealed certain difficulties that are also faced in other countries, particularly, the need to make clear management decisions based on the study of the properties of such vibrant environments as ecosystems.In addition, the situation becomes more categorical due to the lack of clear algorithms and protocols for quantitative assessment of the state and dynamics of ecological systems and their most important property -biodiversity.In order to focus on those aspects of such a multifaceted phenomenon as biodiversity, solving problems according to the EIA Law requires clear criteria.
Ecosystem services should be considered a criterion for justifying practical algorithms and protocols for biodiversity assessment within the framework of environmental-impact assessment (Bohan et al., 2013).Environmental-impact assessment procedure should consider indicators of biodiversity reflecting ecosystem services.Practical tools for assessing biodiversity should detect what components of the ecosystem and at what hierarchical levels are affected by economic activity as a result of implementating a considered project.An important aspect is identifying spatial and temporal scope of the biodiversity assessment, which is directly related to the issue of the actual origin of the probable negative impact on the environment (Inogwabini & Lingopa, 2013).A necessary criterion for assessing the impact on biodiversity is the results of so-called baseline studies.This is due to the fact that each decision is made based on comparison with a certain standard, and the standards of ecological systems are spatially dependent (Villnäs & Norkko, 2011).Therefore, it is possible to standardize the level of deviation from the standard of quantitative characteristics of biological diversity for decision-making, but it is also necessary to clearly indicate the criteria for choosing a standard for comparison, which by definition cannot be universal.
The objective of our study was to determine the impact of road construction on ecologically significant properties of the environment by means of remote sensing.

Materials and methods
Rationale of the research.Methods and means for monitoring soil quality within the sanitary protection zone and on the border of residential development were performed in accordance with the following regulatory documents: Law of Ukraine Landscape metrics.To assess the impact of road construction on environmental regimes, we applied a digital elevation model based on the product ALOS PALSAR RTC 12.5 m DEM (https://search.asf.alaska.edu)(Zhukov et al., 2022).The following derivatives of the digital elevation model were considered as geomorphological variables.
Topographic wetness index.The concept of topographic wetness index (TWI) was first proposed by Beven & Kirkby (1979).Topographic wetness index was calculated by the formula: TWI = ln(a/tanβ), where a is the drainage area (catchment area per unit length of the closing contour), β is the slope steepness (Moore et al., 1993).
Erosion factor (LS). Erosion potential of LS relief is one of the components of Universal Soil Loss Equation (USLE).The LS parameter is the product of L-and S-factors.The L-factor determines the value of slope length, and the S-factor determines the value of slope steepness.The Universal Soil Erosion Loss Equation (USLE), or the Wischmeier-Smith equation, was developed in the United States as a method for calculating average annual soil loss based on generalization of observations on standard 22.13 m long runoff plots with 9% slope conducted at more than 8,000 sites in 21 states.In the first edition of the USLE, a tangent was used to describe the effect of slope steepness, and a constant value of 0.5 was used for the slope length as a measure of degree.Later, the tangent of the slope angle was replaced by a sine function because it was found that this function could more accurately reflect the effect of slope on slopes steeper than 3° (Wischmeier & Smith, 1978).
To model the effect of road construction on the moisture regime and dynamics of erosion processes, the TWI and LS indices were calculated for a digital terrain model without and with road with an elevation that corresponds to the planned level.Therefore, the road was considered as an anthropogenic landform that changes the direction of water redistribution along the topography and thus affects the potential wetting conditions and erosion risks.The geospatial database was created in ArcGIS.Calculations were performed in SAGA GIS (Conrad et al., 2015).Thus, the use of the abovementioned remote-sensing tools allows timely monitoring of the condition of soils and terrestrial ecosystems in the immediate vicinity of the road as a source of environmental hazards within the entire road section with time resolution, which allows for the development of operational measures to prevent negative environmental processes.
Location of the study area.The total area of the 3-km zone of influence (monitoring zone of probable impact) around the national road H-31 Dnipro-Tsarychanka-Kobeliaky-Reshetylivka from the Loboikivka village to the boundary of Dnipropetrovsk Oblast is 373.2 km 2 (Fig. 1).By the end of 2020, the construction the first stage of the road was completed.The area of the right of way for this section is 180.2 km 2 .The area of the second stage of construction is 193.0 km 2 .
There are 18 settlements within the road right of way, which occupy 90.7 km 2 , or 24.3% of the right of way.The minimum distance from settlements to the road varies 0 to 2,968 m (a distance of more than 3,000 m automatically excludes the settlement from consideration).On average, the distance from settlements to the road ranges 360 to 2,981 m.Thus, the settlements are very close to the road and are in the zone of its intensive impact.Soils of the territory where monitoring was carried out are located in the following types of landscapes: solonetssolonchak terrace of the Dnipro River and the first floodplain terrace (arena) of the Dnipro River.Dnipro and the floodplain of the Oril River gradually reaches the placor.According to the digital elevation model, the relief height ranges 53 to 112 m (Fig. 2).From the beginning of the road on the boundary of Poltava and Dnipropetrovsk oblasts, the relief practically does not change for the first five kilometers.

Results
Most of the heights of the study area are in the range of 50-75 m, occupying 88% of the area (Fig. 2).The slope angles vary 0 to 12˚.The average slope is 2.12 ± 0.05˚.High slope angles clearly mark the areas of transition between the main types of landscape of the territory, as well as the beds of water bodies.Territories with slope angle less than 2˚ make up 58% of the area, and with slope angle from 2 to 5˚ -35% of the area.Territories with a slope angle of more than 5˚ account for 6.4%.The topographic moisture index is an integral indicator that combines information about the catchment area and the slope of the relief.These two indicators determine the potential value of the moisture level of a given point and, accordingly, indicate the nature of moisture redistribution as an important factor in soil formation.The topographic moisture index is measured in conditionally dimensionless units (formally, it is the logarithm of the area divided by the tangent of the slope).Within the monitoring area, this index varies 2.93 to 20.06 (Fig. 3).The lowest level of water supply was observed on the plateau on Kalytyva Mountain, and the highest levels of water supply were by the channels of reservoirs.
The histogram analysis of TWI values indicated a bimodal distribution.The fraction of the distribution with higher values corresponded to areas with higher level of moisture in the floodplain or in salt marshes located in the above-floodplain terraces.The fraction with lower values corresponded to areas with lower level of moisture that are located on the plateau or on the first upper floodplain terrace called the arena.In some cases, the road crosses the channel network, which will certainly have implications on soil-formation process due to the redistribution of moisture (accumulation or vice versa, limitation of water supply and intensification of erosion phenomena).To some extent, road construction changes the peculiarities of moisture movement within landscape complexes due to creation of artificial landforms.Modeling construction of the road as an artificial landform allowed us to assess the spatial distribution of the topographic moisture index after the construction.The difference between the observed topographic humidity index and the predicted one provides an opportunity to assess the impact of construction on the humidity regime of the territory.The topographic erosion index within the monitoring area varied 0 to 3.03.The highest erosion risks are relevant in the area of channel network development.The differences in the risks of erosion processes caused by relief features are not statistically significantly different in settlements and outside them (F = 1.17,P = 0.27).Insignificant erosion risks (LS < 0.5) are typical for 79.8% of the territory.This is quite natural, given the generally flat nature of the monitoring area.The moderate level of erosion risks (0.5 < LS < 2.0) is typical for 12.5% of the territory.Above-moderate level of erosion risks (2.0 < LS) is typical for only 1.43% of the area.The moisture availability and erosion risks are interrelated.The driest conditions are most likely to cause erosion, and vice versa: in the wettest conditions deflation is least probable.The lower bound of the corresponding dependence is well described by an exponential functi-on.Its pattern is similar for the territories of settlements and outside settlements.The peculiarity of settlements is that the maximum levels of humidification characteristic of the territory as a whole are observed within settlements.This is natural, as settlements gravitate to water 55 000 50 000 45 000 40 000 35 000 30 000 25 000 20 000 15 000 10 000 5 000 0 bodies of different nature.In turn, no high levels of erosion risks were generally found in the settlements.This is because the settlements avoid the highest or steepest terrain where erosion risks are greatest.Nevertheless, high erosion risks are found within the road construction area and the negative impact of aeolian precipitation on the roadbed, which may occur as a result of deflation, should be taken into account.The construction of a road as an artificial form of relief can affect the progress of erosion phenomena, which are caused by features of the relief.Comparison of LS erosion index values for a given area with those predicted for the situation when the road is fully constructed gives a forecast of changes in erosion processes due to road construction.The transformation of the intensity of erosion processes due to the creation of the road will apply to the entire 3-km zone around the road.It should be noted that the intensity of transformation /is not expected to be signifcant: no or moderate transformation will be observed on 99% of the territory.Thus, only 1% of the territory will be affected by changes in the intensity of erosion due to the road construction.The differences in the level of intensification of erosion processes between settlements and the environment are statistically insignificant (F = 0.23, P = 0.63).The monitoring area is characterized by a specific pattern of predominant directions of water migration.Southwest direction of water movement along the relief is predominant within the monitoring area (17.8%).Other important directions are the southern (18.8%) and western (14.8%).It should be noted that the roadway is at different angles to these predominant directions.Where the roadway crosses such a direction at an angle close to right angle, the impact of the road on water migration will be greatest.

Discussion
Public roads are a component of the unified transport system of Ukraine, providing services of passenger and freight transportations to the population.The environment is all the living and non-living objects that naturally exist on Earth (Huggett, 1999).Environmental impact is any consequence of the planned activity for the environment, including the consequences for the safety of human life and health, flora, fauna, biodiversity, soil, air, water, climate, landscape, natural areas and objects, historical monuments, and other material objects, or for the combination of these factors, as well as the consequences for culturalheritage sites or socioeconomic conditions resulting from changes in these factors (Cluzel et al., 2020;Yorkina et al., 2020;Koshelev et al., 2021).When designing roads, all sources of impact of the road on the environment, including technological processes of road construction and maintenance, are subject to assessment of environmental impact (Zymaroieva et al., 2019;Inti & Anjan Kumar, 2021).During the environmental-impact assessment, it is necessary to compare the quantitative indicators of environmental pollution such as exhaust gases, solid emissions, noise, other factors of vehicles' impact on the environment with maximum permissible concentrations of pollutants in the air, water bodies and soils and other sanitary and hygienic standards established for the given territory (Zhukov et al., 2017;Sun et al., 2021).The levels of the road's impact on the environment are assessed within the territories adjacent to a roadway, which are subject to direct or indirect environmental impact of the projected facility (Lee & Power, 2013;Jiang & Wu, 2019;Zhukov et al., 2021).They are divided as follows: the impact zone, the protective zone, and the reserve and technological zone (Zhang et al., 2020;Budakova et al., 2021).
Types of impact of the road on the environment (Condurat et al., 2017) are as follows: emissions from vehicles moving on the road (transport pollution) (Liu et al., 2022), exhaust gases (Kanda et al., 2006;Marjanen et al., 2022), traffic noise (Khomenko et al., 2022), dust in the form of solid emissions, and wear products of pavement and tires that pollute the air (Gustafsson et al., 2019), soil, and water bodies in the adjacent area.The changes in economic and natural systems as a result of road construction: temporary withdrawal of land, reformation of relief, changes in runoff, level, and conditions of groundwater movement (Kunakh et al., 2020), separation of biosystems and farmland, existing infrastructure.Technological impacts during construction and repair works are: pollution of air, soil and water bodies during the operation of road machines, industrial noise, dust spread, temporary land withdrawal (Zymaroieva et al., 2019).The main objects of the road impact on the natural environment are: climate and microclimate; air environment; geological environment; water environment; soils; flora and fauna, protected areas.The sources of impact on the geological environment and soil-forming rocks are technological processes of construction and the road as an engineering structure (Zymaroieva et al., 2021).During the construction of roads, the impact on soil-forming rocks can be direct or indirect.The direct impact of road construction on soil-forming rocks is manifested in the activation of exogenous and endogenous processes that can disturb the stability of the road under construction, artificial structures, and other natural and manmade objects in the zone of its influence (Domnich et al., 2021).The indirect impact of new construction and reconstruction of roads on soilforming rocks is manifested in the activation of dangerous natural processes, leading to transformation of the ecosystems.The main forms of impact of roads on soil-forming rocks are removal of soil and vegetation, local changes in relief; shapes of river channels, and channel processes, deepening of channels; destruction of vegetation; changes in terrain; drainage and watering of the area; and groundwater level, and also flooding (Zhukov et al., 2017); changes in hydrological regime, slope stability, channel shape, flow velocity; intensification of water or wind erosion; landslides, changes in the conditions of local water runoff and surface and groundwater runoff; denudation processes, landslides; fragmentation of biogeocenosis, changes in agrotechnical conditions; changes in the drainage system, landslides.Design solutions, the implementation of which may lead to a rise in the groundwater level and flooding, are developed in conjunction with protective measures that exclude swamping and drainage of the territory adjacent to the road.
Analysis of the impact on soils includes: analysis of the impact of the road on soils, taking into account the peculiarities of land use, availability of areas of valuable agricultural land, chemical, biological, and radioactive pollution, vibration, occurrence of dangerous engineering and geological processes and phenomena and other factors that adversely affect the condition of soils; assessment of the impact of road on the condition of soils, taking into account the genetic types of soils, characteristics of their humus composition, mechanical and waterphysical properties, landscape geochemistry, and animal population.Monitoring of the impact on vegetation cover of soils and animal population of soils includes: characterization of their state and assessment of the transformation based on the materials of field studies; analysis of the impact of the road on the vegetation cover and animal population due to pollutants entering the environment; assessment of changes in the composition of plant communities and animal population, species diversity, populations of dominant, valuable, and protected species.Impacts of construction, repair, and operation of the road on soil vegetation and animal population can be direct (mechanical damage, destruction, degradation of habitats) or indirect (as a result of pollution with waste, exhaust gases, polluted wastewater, sedimentation of substances in the form of suspended solids, changes in the conditions of animal migration, etc.).
The impact on soils during new construction and reconstruction of roads occurs during planning, preparation of the territory, excavation works, trenching, and creation of embankments.Soil pollution during construction works is possible in cases of fuel and oil spills from vehicles and construction machines, as well as possible contamination of the territory with waste and garbage.Measures to ensure the normative condition of land resources during new construction and reconstruction of roads should include: mandatory observance of the boundaries of the territory, the designated lane for road construction; removal and storage of vegetative soil in specially designated areas with its subsequent use in reclamation, vertical planning; placement of construction materials in a specially designated area with a hard surface; control over the operation of engineering equipment, mechanisms, and vehicles.
Local monitoring of soils consists of systematic observations of their condition, detection of changes, as well as assessment: processes associated with changes in soil fertility (development of water and wind erosion, loss of humus, deterioration of soil structure, waterlogging, and salinization), agricultural land being overgrown, land contamination with pesticides, heavy metals, radionuclides, and other toxic compounds; condition of river banks, edges of seas, lakes, bays, reservoirs, estuaries, hydraulic structures; processes associated with the formation of ravines, landslides, rural streams, earthquakes, karst, cryogenic, and other phenomena; condition of lands in settlements, territories occupied by oil-and gas-production facilities, treatment facilities, manure-storage facilities, warehouses of fuels and lubricants, fertilizers, parking lots, disposal of toxic industrial waste and radioactive materials, as well as other industrial facilities.Depending on the period and frequency of their conduct, land monitoring is divided into: basic (initial, repair of the state of object of observation at the beginning of land monitoring); periodic (conducted in a year or more); operational (repair of current changes).Land monitoring is carried out in the following order: special surveys and land surveys; identification of negative factors, the impact of which requires control; assessment, forecast, prevention of the impact of negative processes.
The modeling results indicate that the transformation of the water regime will be observed within the entire 3-km monitoring area.Deviations from the normal value can be up to 7 units by module, which is about one third of the landscape-wide range of topographic moisture index values.Almost no impact of construction can be predicted for 80.7% of the territory.Increase in moisture regime will be moderate for 10.6% and very significant for 3.2% of the area.In turn, 4.3% of the area will undergo moderate decrease in humidification, whereas for 1.2% the decrease will be very significant.The greatest impact on the redistribution of moisture conditions is predicted in the immediate vicinity of the road.Both increase and decrease of edaphic moisture is possible, but the trend of moisture decrease in the immediate vicinity of the road will prevail.The conditional distance, where the number of increasing alternatives is compensated by the number of decreasing alternatives, is 200 m.It should be noted that the territories of settlements will not be subject to this type of impact.Obviously, this is related to the fact that the relief features of settlements have already undergone anthropogenic transformation, and therefore are not sensitive to road construction.Changes in the moisture regime can have significant negative consequences for both soil cover and biotic components of ecosystems.Changes in vegetation following changes in both moisture and trophic conditions can be considered as possible scenarios for the development of landscape-cover dynamics.Trophic changes are related to the moisture regime, as excessive moisture combined with capillary rise and evaporation can lead to increased soil salinity.As vegetation alternatives, the most likely is the replacement of natural plant associations with ruderal ones.Reduction of moisture may entail a decrease in the productivity of ecosystems and their xerophytisation.In this regard, given the significant population of the territory, occurrences of fires cannot be excluded.Relief is also an important factor that affects the dynamics of soil-erosion processes.The thickness of humus layer of soil is a function of the processes of humus formation and its loss due to erosion.The balance of these processes provides the soil layer with a stable thickness.The predominance of one of the processes leads either to thinning or thickening of the layer.

Conclusion
Comparison of patterns of predominant directions of water migration on the relief surface before and after the road construction allowed us to determine the main aspects of its transformation.The zones of the main transformation of water-movement directions are concentrated in places where the road significantly changes its direction.These are areas that are closest to the road at a relatively short distance, as they relate to the direct impact of changes in the shape of the relief due to road construction.Thus, the impact of construction on the redistribution of moisture is widespread, as the intersection of water flow leads to its accumulation within one local catchment and restricts its flow to another.The areas of such local catchments can be widely distributed.The direction of water flow can be changed only due to changes in relief and only within the area where these changes occurred.Obviously, road construction along the direction of preferred moisture flows will not have a significant impact on the direction of water flows.A sharp change in the direction of the road in the vast majority of cases is due to engeneering solutions and does not agree with the directions of natural movement of water on the ground, and therefore will have a significant impact on the direction of water flows.These phenomena will certainly contribute to the intensification of water erosion and movement of soil masses.Such areas require special attention in terms of studying the stability of soil cover in the immediate vicinity of road.Activation of erosion phenomena due to road construction can have negative consequences both for the road itself and the environment.In turn, the negative impact on the road condition can cause unpredictable consequences for the environment.Erosion and deflation of the soil surface should be compensated by such environmental measures as soil restoration.Such measures include improvement of surface runoff, strengthening, and terracing of slopes, agrotechnical and forest reclamation works.If necessary, gullies should be completely or partially eliminated by filling them with gravel and sand.

Fig. 1 .Fig. 2 .
Fig. 1.Map of the territory in the construction zone of the road of national importance H-31 Dnipro-Tsarichanka-Kobeliaky-Reshetylivka from Loboikivka village to the border of Dnipropetrovska oblast and the border of the 3-km zone of influence (monitoring zone of probable impact): brown color of the road is the construction phase until the end of 2020, green color is the next stage of road construction (a) and digital elevation model of the territory (b)

Fig. 3 .
Fig. 3. Topographic wetness index (a) and predicted changes in the topographic wetness index (b)that may be caused by road construction (difference between predicted and observed values)