Anthropogenic and Environmental Geomorphology

• Anthropogenic geomorphology is the study of humans as a geomorphic agent: how economic and developmental activity creates new landforms and modifies the rate and mechanism of natural geomorphic processes.
  • Its concepts and vocabulary are collected in our anthropogenic geomorphology terminology page.
• It is a branch of applied geomorphology, which uses geomorphic knowledge for resource evaluation, hazard management and planning.
• Its twin field, environmental geomorphology, looks at the same relationship from the other side: how landforms and processes affect people (hazards, resources) and how that knowledge guides land use.

Anthropogenic Geomorphology: Concept and Development

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Meaning and Concept

• Geomorphic processes now fall into two broad groups:
  • Natural (physical environmental) processes: endogenetic forces from the earth’s interior create relief; exogenetic processes driven by solar energy (weathering, fluvial, glacial, aeolian and marine work) wear it down. See exogenic forces.
  • Anthropogenic processes: natural processes modified, accelerated or retarded by human action, plus entirely new human processes such as excavation and dumping.
• Why humans matter as an agent
  • Natural systems stay in dynamic equilibrium through negative feedback; human interference often pushes them past thresholds, so change becomes rapid and self-reinforcing.
  • Humans alter the landscape many times faster than most natural processes, and through it disturb the energy, hydrological, chemical-element and sediment cycles.
  • Natural processes follow equifinality (different routes, similar end-forms); human processes add forms with no natural counterpart, such as open pits, spoil heaps and reservoirs.
• Two ways of classifying human effects
  • Deliberate (planned) effects: embankments, channel straightening, sea walls, terraces, afforestation of dunes.
  • Inadvertent effects: accelerated erosion after forest clearance, subsidence over mines, reservoir-triggered earthquakes, beach loss downdrift of a harbour.

Direct and Indirect Anthropogenic Processes

• Andrew Goudie (1981), in The Human Impact on the Natural Environment, grouped human geomorphic processes into direct and indirect ones.
  • Direct processes are usually intentional and produce recognisable new forms.
  • Indirect processes do not create a new process; they accelerate an existing natural one, and are harder to detect and predict.

Historical Perspective

• Early phase: humans altered processes from the beginning of settled farming, but the scale jumped after the Industrial Revolution and again after the Second World War.
• George Perkins Marsh (1864), Man and Nature, is the pioneer work.
  • It documented the extent of human-made change in the physical condition of the globe, warned against imprudent large-scale interference, and argued for restoration of disturbed harmonies.
• A long lull (to about 1920)
  • Physical geography was dominated by evolutionary thinking after Charles Darwin (1859): the Davisian cycle of erosion, plant succession and zonal soils all treated landscape as developing naturally, leaving little room for human agency.
• Robert Lionel Sherlock (1922), Man as a Geological Agent, revived the theme.
  • He separated natural (geological) denudation from human denudation and argued that in densely settled England human excavation outstripped all atmospheric denudation combined.
• Soil erosion and synthesis
  • Graham Vernon Jacks and Robert Orr Whyte (1939), The Rape of the Earth, gave the first world survey of human-accelerated soil erosion.
  • The 1955 Princeton symposium, published as Man’s Role in Changing the Face of the Earth (edited by William L. Thomas, 1956), turned individual concern into a collective interdisciplinary field.
• Measurement era (after 1950)
  • Interest shifted to measuring contemporary process rates; around Rome, for example, present erosion rates were shown to be several times the pre-human rate.
  • Richard J. Chorley and Barbara A. Kennedy (1971) placed humans as the regulator in the control system of their systems framework (morphological, cascading, process-response and control systems).
• Four trends of the 1960s–70s
  1. Comparative measurement of human-accelerated erosion rates.
  2. Study of natural and environmental hazards.
  3. International programmes: UNESCO’s International Hydrological Decade (1965–74) and the Man and the Biosphere Programme (1971).
  4. Environmental concern, voiced by works such as Rachel Carson’s Silent Spring (1962).
• Institutional growth: Donald R. Coates edited Environmental Geomorphology (1971) and Urban Geomorphology (1976); Andrew Goudie (1981) gave the standard synthesis; international conferences on geomorphology and environmental management followed from 1985.
• Current view
  • Roger LeB. Hooke (2000) called humans “arguably the premier geomorphic agent”, with earth-moving rising exponentially.
  • A British Geological Survey study led by Anthony H. Cooper (2018) estimated that humans move about 316 billion tonnes of sediment a year, roughly 24 times the load carried by the world’s rivers.

The Anthropocene Debate

• Paul J. Crutzen and Eugene F. Stoermer (2000) proposed the Anthropocene as a new epoch in which humans dominate earth-surface systems.
• The Anthropocene Working Group proposed a start in the early 1950s (the “Great Acceleration”), with a golden spike in the varved sediments of Crawford Lake, Ontario, marked by plutonium from bomb tests.
• In March 2024 the Subcommission on Quaternary Stratigraphy rejected the proposal (12 against, 4 for), and the International Union of Geological Sciences (IUGS) confirmed the decision.
  • The Holocene remains the current epoch; the IUGS noted that “Anthropocene” will stay in wide informal use for human impacts.
  • Critics argued that human impact is diachronous (spread over thousands of years, from early farming onwards) and cannot be pinned to one synchronous boundary.
• For geomorphology the debate matters because anthropogenic landforms and artificial ground are now mappable stratigraphic units in their own right.

Human Impact on Geomorphic Processes

Hydrological Processes

• Natural drainage-basin cycle
  • Input: precipitation, partly intercepted by vegetation and reaching the ground as throughfall and stemflow.
  • Storages: surface storage → infiltration to soil-moisture storage → percolation to groundwater storage; soil water returns to channels as throughflow and interflow, groundwater as base flow.
  • Outputs: evapotranspiration from every storage, and channel runoff.
• Human modification of each component is summarised below; the related terms appear in our applied geomorphology and geohydrology terminology page.

• Forest versus cleared land
  • In forest, the canopy breaks raindrop energy; more water infiltrates, flood peaks fall and recharge rises.
  • On bare ground, raindrops compact the surface, infiltration drops and overland flow rises, giving floods in the wet season and poor recharge.
• Urbanisation changes basin hydrology in two ways:
  • Impervious surfaces (roofs, roads, pavements) cut infiltration: flood peaks rise during storms while dry-season base flow falls, widening the gap between high and low flows.
  • Storm drains and sewers deliver runoff quickly, shortening lag time between rainfall and peak discharge and producing urban flash floods.
  • Indian examples: Chennai (2015), and repeated urban floods in Bengaluru, Hyderabad and Mumbai, where built-up land has replaced lakes, tanks and natural drains.
• Land drainage of fields and forests lowers water tables and increases mean runoff and flood frequency.
• Water quality also changes: sediment, effluents, salinisation in canal-irrigated semi-arid land (for example parts of Punjab, Haryana and the Indira Gandhi Canal command) and eutrophication from fertiliser nutrients, which are several times higher in farmed than in forested catchments.

Weathering and Mass Movement

• Humans accelerate weathering directly and indirectly (details of the natural processes are in our note on weathering and mass movement).
  • Mining, blasting and quarrying (for example limestone for cement) break rock in days as much as weathering does in thousands of years.
  • Acid rain from sulphur and nitrogen oxides speeds chemical weathering of limestone, marble and monuments.
• Deforestation and slope stability
  • Tree roots mechanically reinforce regolith and add cohesion; clearance removes this and makes slopes prone to slides, slumps and debris flows.
• Human-induced mudflows and earthflows have two main causes:
  • Dumped mine waste in large unstable piles that flow laterally.
  • Removal of support by undercutting the base of slopes for roads, canals, dams and buildings.
• Roads in weak rock
  • Where roads are cut in shales beneath resistant sandstones, as along the Kaimur and Rewa plateau scarps, roadside walls collapse into earthflows almost every monsoon; the same happens throughout the Himalaya.
• Hill-town encroachment
  • On upper hillslopes the factor of safety is close to unity, so extra load, cutting, and leaking water pipes, sewers and soak pits can trigger failure.
  • Nainital: the landslide of 18 September 1880, after about three days of very heavy rain, killed 151 people; its debris filled part of the lake and formed the flat ground now called The Flats. Construction has since spread up the same shale and dolomite slopes.
  • Shimla (2023 monsoon) and Joshimath (2023) show the same risk in recent years.
• Remedy: survey slope angle, lithology, safety factor, groundwater and regolith before roads and buildings are laid out.

Coastal Processes

• Waves and tidal currents build and destroy coastal landforms naturally; humans modify them mainly at harbours, resorts and reclaimed land.
• Direct interventions include:
  • Resisting waves with sea walls, groynes and breakwaters.
  • Beach nourishment (importing sand) and dune planting.
  • Dredging channels and reclaiming marshes and mudflats; dredged hollows and dumped mounds offshore change wave direction and energy, and a deepened sea floor lets larger waves reach the shore.
• These seldom work as planned, because blocking longshore drift at one place starves the coast further along.

• Breakwaters and drift: Indian cases
  • Chennai: the harbour breakwaters stopped the northward drift; sand piled up to the south, forming the wide Marina beach, while the coast to the north (Royapuram to Ennore) eroded. North of the Ennore port breakwater, erosion has reached about 40 m a year.
  • Puducherry: after the port breakwaters of 1989, the city beach to the north disappeared within a decade; an artificial submerged reef with nourishment has since partly restored it.
• Sediment-supply changes
  • Quarry waste tipped on coasts can build new beach ridges (east coast of Jutland, Denmark).
  • Beach sand mining removes the natural buffer: the Sochi coast (Black Sea) had to be refilled after quarrying, and along Chavara–Alappad (Kollam, Kerala) mineral-sand mining is linked to severe shoreline loss.
  • Upstream deforestation raises sediment supply and makes deltas and bay-head beaches grow (Mediterranean river mouths).
  • Dams trap sediment and reverse delta growth: after the Aswan High Dam (1970), the Nile’s Rosetta promontory retreated by over 100 m a year until sea walls were built in 1991.
  • Coastal dunes are destabilised by clearing, burning and grazing, and stabilised by planting (Landes, south-west France; Culbin, Scotland).
  • Reclamation of tidal flats (the Netherlands, Mumbai’s seven islands) gains land but brings weak foundations and loss of estuarine habitat.
• Present Indian picture: the National Centre for Coastal Research found that between 1990 and 2018 about 33.6% of India’s mainland coast was eroding, 26.9% accreting and 39.6% stable. The CRZ Notification 2019 sets no-development zones and hazard lines.

River Processes

• Rivers are both boon and bane: the Ganga sustains the northern plains, while the Huang He (“China’s sorrow”) and the Damodar (once “sorrow of Bengal”) are known for floods and shifting courses.
• Human modification of channels (see channel morphology) is direct (intentional) or indirect (inadvertent).

Direct Modifications

• Point modifications act at one site.
  • Dams and reservoirs reduce flood peaks and trap sediment; the sediment-free “hungry water” released below scours the bed and banks downstream.
  • Abstraction and lift irrigation in the lean season reduce flow, so the river cannot carry its load and its bed silts up, raising later flood levels.
  • Bridges constrict and redirect flow. A road bridge on the Gomti near Kaithi (Varanasi district) straightened a bend, and in 1980 the Gomti–Ganga confluence shifted about 2 km upstream.
• Reach modifications act along a long stretch.
  • Channelisation (straightening, widening, deepening) speeds flood water downstream. Between 1929 and 1942, a series of cut-offs shortened the lower Mississippi by about 245 km (152 miles) between Memphis and Old River.
  • Straightened alluvial rivers tend to re-develop meanders, because meandering is their natural adjustment.
  • Bank protection (revetments, spurs, dikes) stops local bank erosion but cuts sediment supply and causes scour further downstream.
  • Embankments and levees confine floods but also confine sediment, so the bed aggrades between them.
• Indian cases
  • Kosi: embanked since the 1950s, the river raised its bed between the embankments; on 18 August 2008 it breached the embankment at Kusaha (Nepal) and moved into an old channel near the centre of its fan, affecting about 3 million people in Bihar.
  • Farakka Barrage (1975): siltation upstream and severe bank erosion in Malda and Murshidabad, with the river shifting towards the left bank.
  • Riverbed sand mining in the Ganga, Yamuna, Narmada and Kerala rivers lowers beds, undermines bridges and lowers riverside water tables.

Indirect Modifications

• Catchment changes (deforestation, farming, mining, road building, urban construction) raise both discharge and sediment load, driving river metamorphosis: changes in channel geometry, planform (for example from single-thread to braided) and sediment transport.
• Urban construction yields a pulse of sediment that lasts only while building continues; mining and highways in hills are longer-lasting sources.
• Human action can also cut loads: the Yellow River’s sediment load has fallen by about 90% in sixty years through dams and soil conservation on the Loess Plateau.

Periglacial Processes

• Periglacial areas have frozen ground but no permanent ice cover.
  • Permafrost is the permanently frozen layer; above it the active layer (a few centimetres to about 3 m) freezes in winter and thaws in summer.
  • The ground actually underlain by permafrost is estimated at roughly 15% of the Northern Hemisphere’s exposed land (the wider permafrost region is nearer a quarter); the largest areas are in Siberia, Alaska and northern Canada, with pockets in the high Himalaya and Ladakh.
• Two processes matter most for people:
  • Thermokarst: collapse and subsidence of ground when ground ice melts after the thermal equilibrium is disturbed; most active in unconsolidated, ice-rich material.
  • Frost heave: bulging of the surface through ice segregation.
• Human disturbances that upset permafrost:
  • Vegetation removal, since the plant cover insulates the ground; clearing near Fairbanks (Alaska) in the 1920s produced a hummocky surface of mounds and pits.
  • Excavation for roads, airstrips, pipelines and cables.
  • Vehicle tracks on thawed ground, which become ruts and then gullies.
  • Heated buildings and forest fires, which deepen the active layer.
• Effects: deformed roads, railways and buildings. Early stretches of the Trans-Siberian Railway subsided after clearing; the Trans-Alaska Pipeline (1977) was carried largely above ground on vertical supports so that hot oil would not thaw the ground.
• Climate warming now adds to local disturbance. The Norilsk fuel spill (May 2020) was linked partly to foundations failing as permafrost thawed, and permafrost thaw on moraines contributed to the South Lhonak collapse in Sikkim (2023).

Subsurface Processes

• Subsurface change is slow, cumulative and hard to detect until damage is done; it follows when human stress exceeds the strength of the ground.
• Humans act by adding load or removing load and support.

• Koyna: the reservoir was impounded in 1962; on 11 December 1967 a magnitude 6.3 earthquake near the dam killed about 180–200 people. It remains the classic case of reservoir-induced seismicity, and seismicity still rises with reservoir level.
• Mine dewatering in limestone or dolomite causes sinkholes: dewatering of deep gold mines in the Far West Rand (South Africa) in the 1960s opened sinkholes up to about 125 m across.
• Old flooded workings are a hazard: at Chasnala (Dhanbad, now Jharkhand) on 27 December 1975, water from an abandoned adjoining working burst into an active mine and killed 375 miners.
• Jharia coalfield: underground fires reported since 1916 cause subsidence and cracks over a wide area, forcing resettlement under the Jharia Master Plan.
• Other effects of underground mining: diversion of groundwater, drying springs, rock bursts (as in the deep Kolar gold mines), gas release. Blasting for roads and dam sites, and above all nuclear tests, deform the surface and can trigger tremors; heavy buildings on recently filled ground also settle.

Pedological Processes

• Soil takes centuries to form but can be degraded in years. Humans act on its labile properties (those that respond quickly to outside change).
• Direct effect: complete loss of horizons through accelerated erosion on cleared slopes.
• Indirect effects:
  • Ploughing homogenises the profile: in chalk soils, ploughing spreads humus through the profile, cutting surface organic carbon from about 8–14% to 2–3%, while bringing up chalk raises carbonate content sharply.
  • Organic matter responds faster to human change than mineral content, as long-term studies on reclaimed and enclosed land show.
  • Heavy machinery and overgrazing compact wet soils and damage structure.
  • Persistent pesticides and herbicides and heavy metals (lead, mercury, cadmium, chromium) accumulate; acidic soils mobilise metals into plants and water, alkaline soils retain them.
  • Fertilisers: soluble nitrates leach into streams and cause eutrophication; phosphates are fixed in acidic and alkaline soils.
• Approach: study natural profiles first, then the response of profiles to farm inputs, and finally plan conservation. In India, soil organic carbon has fallen widely under intensive cropping.

Human-Induced Soil Erosion

• Humans now accelerate the natural (geological) rate of erosion through three groups of change:
  1. Land-use change: clearing forest and grassland for farms, cities, mines, roads and dams.
  2. Farm-practice change: heavy machinery, wheel traffic and shifts between crops, orchards and ranching.
  3. Crop and land management: fertiliser use, tillage method, fallowing.
• How each natural control is altered
  • Climate factor: without canopy, raindrops strike bare soil at full energy; rain-splash erosion rises, fine particles seal pores and crust the surface, and runoff increases.
  • Topography: terraces, bunds, quarries, road cuts, canals and drains change slope length and gradient. Erosion from building sites is intense but lasts only during construction.
  • Soil properties: clearing, ploughing and machinery change organic matter and structure. On kachhar lands (flood-renewed valley sides of Indian alluvial rivers) furrows ploughed across the slope towards the river become channels for the next monsoon’s runoff.
  • Grazing: sheep, goats and cattle strip cover and trample soils.

Regional Pattern of Erosion

• It is hard to separate natural from human erosion, but estimates suggest humans account for over half of present erosion, dominant in monsoon, semi-arid, Mediterranean and converted grassland regions.
• Land-cover experiments show the scale of the effect:

• Strip mining is extreme: in a Kentucky mining district sediment yield exceeded 10,000 t/km²/yr against about 10 t/km²/yr from undisturbed watersheds.
• Grassland biomes (steppes, prairies, pampas, veld, Australian downs) became erosion zones after conversion to cropland.
• India
  • An estimated 5.3 billion tonnes of soil is eroded each year; about 29% reaches the sea, about 10% settles in reservoirs, and the rest is redeposited within basins.
  • ISRO’s Desertification and Land Degradation Atlas (2021) mapped about 97.85 million ha (about 30%) of the country as degraded in 2018–19; water erosion is the largest single process (about 11% of the geographical area).
  • Ravines cover about 3.67 million ha, mainly in Madhya Pradesh, Uttar Pradesh, Rajasthan and Gujarat; the Chambal ravines (gullies up to about 80 m deep) are among the largest badlands in the world, with smaller tracts along the Yamuna, Betwa, Ken, Tons, Mahi and Sabarmati.
  • Hotspots include the Siwaliks and middle Himalaya, the Brahmaputra valley, the north-eastern hills under shortened jhum cycles, the Western Ghats and the bare Aravallis.
  • Forest cover is 21.76% of the geographical area (forest and tree cover together 25.17%) in the India State of Forest Report 2023, well short of the national goal of one-third.

Sedimentation

• Sedimentation is the chain of erosion → transport → deposition in channels, lakes, reservoirs and seas.
  • Geological erosion is the slow natural rate; accelerated erosion is the extra erosion caused by land-use change.
  • Sediment yield is the sediment removed from a unit area in unit time (t/ha/yr or t/km²/yr); a river’s sediment load is its suspended load (clay, silt, fine sand) plus bed load (sand to cobbles).
• Global scale: rivers deliver about 15–20 billion tonnes of solid sediment and about 4 billion tonnes of dissolved material to the oceans each year.
• Tropical, subtropical and Mediterranean rivers carry far higher loads than temperate and polar rivers because of heavy seasonal rain plus deforestation.

• Ganga system in Uttar Pradesh: of the sediment passed on to Bihar, about 39% comes from the Himalaya, 36% from the Vindhyan uplands (through the Chambal, Betwa and Ken, largely from ravine lands) and 25% from the alluvial plains.
  • Silt-load per unit area is highest near the mountain front (at Rishikesh) and falls downstream, showing that Himalayan catchments erode fastest.
  • The Ganga’s bed at Allahabad (Prayagraj) has aggraded measurably in recent decades, causing braiding, course shifts and larger floods; lean-season canal diversions worsen this.
• Mining sediment: coal strip-mining in the Damodar valley (Jharia, Raniganj) supplies coarse waste that aggrades channels and silts the Damodar Valley Corporation reservoirs, as in the Appalachian coalfields.
• Two effects on farmland: coarse sand from bare hills buries fertile fields, while fine floodplain silt enriches them.
• Reservoir sedimentation fills storage, damages turbines and causes scour below dams. A UN University study (2023) estimated that India’s roughly 3,700 large dams will lose about 26% of their original storage by 2050.

Scarification

• Scarification is the direct scarring of the land surface by human excavation and dumping: mining, quarrying, road and rail cuts, construction and waste tipping.
  • It is treated as human-induced mass movement, because it shifts earth materials in bulk, far faster than natural slope processes.
  • It is the clearest case of a direct (excavational and constructional) anthropogenic process, producing forms with no natural analogue.
• Types

• Scale: the Bingham Canyon copper mine (mined since 1906) is about 4 km wide and 1.2 km deep; in April 2013 its wall failed in the Manefay landslide (about 65–70 million m³), possibly the largest historic non-volcanic landslide in North America, predicted in time by slope-monitoring radar.
• Impacts
  • Landform: new pits, benches, dumps and truncated hills; the Supreme Court in 2018 was told that 31 hills of the Aravalli in Rajasthan had disappeared through illegal mining.
  • Slope instability: steep pit walls and loose dumps generate slides, flows and tailings-dam failures.
  • Erosion and sedimentation: bare spoil yields far more sediment than undisturbed ground, aggrading streams and silting reservoirs.
  • Hydrology: lowered water tables, drying springs, acid mine drainage and polluted streams, as from rat-hole coal mining in Meghalaya (banned by the National Green Tribunal in 2014).
  • Subsidence and fire over underground working (Jharia).
  • Soil, ecology and people: loss of topsoil and forest, dust, displacement; the Supreme Court halted iron-ore mining in Goa in October 2012 after large-scale illegal extraction.
• Management: restrict mining in fragile zones, backfill and reclaim worked land (topsoil storage, benching, revegetation), stabilise dumps, treat mine water, and enforce sand-mining rules (the 2016 and 2020 national guidelines).

Environmental Geomorphology and Hazards

Environmental Geomorphology

• Donald R. Coates (1971) defined environmental geomorphology as the practical use of geomorphology to solve problems where humans wish to use and transform landforms.
  • His edited volume came from the first Binghamton Geomorphology Symposium (1970).
• It is two-way:
  • Landforms and processes → people: hazards and constraints (floods, landslides, subsidence, coastal erosion) and resources (aquifers, soils, building materials, placers).
  • People → landforms and processes: the anthropogenic changes described above.
• Scope

• Examples of natural landforms and processes affecting people
  • Floodplains and fans attract settlement yet flood: the market of Dharali (Uttarkashi) stood on the debris fan of the Kheer Gad and was buried on 5 August 2025.
  • Unstable slopes under towns (Joshimath, Nainital), active coasts (Chennai, Kerala) and karst (sinkhole collapse) all constrain use.

Himalayan Geomorphological Hazards

• Why the Himalaya is hazard-prone
  • Tectonics: young, still-rising mountains along the Main Central Thrust, Main Boundary Thrust and Himalayan Frontal Thrust; much of the range lies in seismic zones IV and V.
  • Relief and rocks: steep slopes, deep gorges and sheared, fractured, weathered rocks, many settlements on old landslide and moraine debris.
  • Climate: intense monsoon rain and cloudbursts; rapid glacier retreat leaves moraine-dammed lakes, and permafrost thaw weakens high slopes (see glacial landforms).
  • Process cascades: landslide → river blockage → outburst flood → debris flow, so one trigger spreads far downstream.
• Human amplification: road widening and blasting, hydropower tunnels and dams in narrow valleys, unregulated towns on steep slopes, and deforestation.
  • ISRO’s Landslide Atlas of India (2023) mapped about 80,000 landslides (1998–2022); about 12.6% of India’s land (0.42 million km²) is landslide-prone, and Rudraprayag and Tehri Garhwal are the most exposed districts.

• Joshimath: the Mishra Committee (1976) had already warned against heavy construction, blasting and poor drainage on the town’s landslide debris; the warnings were not followed.
• Western Ghats parallel: Wayanad (30 July 2024): after two days of extreme rain, a rockslide turned into a fast debris flow that devastated Mundakkai, Chooralmala and Punchirimattom, among the deadliest landslides in Kerala’s history. Loss of forest, plantations and quarrying on steep slopes are cited as aggravating factors.
• Evaluation: geomorphic change (uplift, slope steepening, glacier retreat, permafrost thaw) sets up the hazard, but human exposure and interference turn it into disaster; climate warming now raises the frequency of extreme rain and glacial-lake growth.

Degradation of Hills and Hillslopes and Down-Valley Impact

• Causes of hill degradation
  • Deforestation for timber, fuel, farmland and plantations.
  • Road building with blasting and unmanaged debris dumping down slopes.
  • Mining and quarrying: limestone in the Doon valley (curbed by the Supreme Court in the 1980s), stone in the Aravallis, coal in Meghalaya.
  • Hydropower tunnels, dams and muck disposal.
  • Tourism and urban growth beyond carrying capacity (Shimla, Mussoorie, Nainital, Darjeeling).
  • Shortened jhum cycles in the north-east and overgrazing.
  • Abandoned terraces after out-migration, and climate change (glacier retreat, heavier rain, thawing permafrost).
• Down-valley impacts

Management and Mitigation

• Hazard mapping and warning
  • Landslide susceptibility and zonation maps; InSAR monitoring of slopes and towns.
  • Glacial-lake inventories, GLOF early warning and lake-lowering (siphoning at South Lhonak before 2023).
  • Flash-flood and cloudburst forecasting.
• Slope and catchment treatment
  • Retaining walls, drainage, rock bolting, catch fences.
  • Bio-engineering with grasses and shrubs.
  • Watershed management with check dams, contour bunds and afforestation.
  • Ravine reclamation by gully plugging, peripheral bunds and planting.
• Regulation and planning
  • Carrying-capacity studies for hill towns and building bylaws for slopes.
  • Floodplain zoning, CRZ 2019, EIA for dams and roads, and sand-mining guidelines.
• Rivers and coasts
  • Room for rivers rather than ever-higher embankments; sediment management and flushing at dams.
  • Soft coastal defences such as beach nourishment, submerged reefs and mangrove and dune planting in place of hard walls.
• Mines and quarries
  • Backfilling, topsoil reuse and progressive reclamation; control of fires and subsidence.
• Principle: understand the geomorphic threshold of each landscape before altering it, the core aim of applied and environmental geomorphology.