CHSE Odisha Elective Geography key terms

The overall wearing away of the land surface through weathering, mass movement, erosion and transport, lowering relief over long periods. It combines processes that break rock in place with those that remove the debris.

The breakdown of rock in situ by physical, chemical or biological processes without the material being carried away. Freeze-thaw, hydrolysis and root wedging are common examples. It prepares rock for erosion and transport.

The peeling of outer rock layers in curved shells, usually caused by repeated heating and cooling or by pressure release as overlying rock is removed. Common in coarse-grained rocks such as granite in hot desert climates.

The loose layer of broken rock, mineral grains and soil that rests on solid bedrock. Its thickness depends on weathering rate, rock type and slope. It is the source material for soil and for many slope failures.

The downslope transfer of soil and rock under gravity, without a transporting medium such as water or wind. Creep, slump, slide and flow are the main types, classified by speed and water content.

The lowest elevation to which a river can erode its bed, normally sea level but locally a lake or resistant rock bar. As base level falls, the river gains energy and cuts down; as it rises, deposition begins.

A nearly flat, gently rolling erosion surface produced after long-continued denudation of a region, often with isolated resistant hills called monadnocks. It represents the late stage of the Davisian cycle of erosion.

Renewed downward erosion along a river after a fall in base level, caused by uplift or a drop in sea level. Signs include incised meanders, river terraces and knickpoints along the long profile.

A former floodplain left standing as a step above the present river after renewed incision. Terraces record earlier levels of the valley floor and are useful for recognising uplift or climatic change in a basin.

The flat land beside a river built up by sediment deposited when the river overflows its banks. It is usually fertile and densely settled, but it is also the zone most exposed to river flooding.

A raised ridge of coarse sediment deposited along a river bank when floodwater slows and drops its load. Natural levees are built by repeated floods; artificial ones are embankments raised to protect land behind.

A low, often triangular plain of sediment built where a river enters standing water and loses velocity. Shape depends on sediment supply, wave and tide strength, and subsidence, giving arcuate, bird-foot or estuarine forms.

The incoming solar radiation received at the Earth's surface, measured per unit area over time. Its intensity varies with latitude, season, time of day and cloud cover, and it drives atmospheric and ocean circulation.

The proportion of incoming solar radiation reflected by a surface, expressed as a fraction or percentage. Fresh snow reflects most of it, dark ocean and forest little. Differences in albedo affect local and global heat budgets.

The rate at which atmospheric pressure changes over horizontal distance. The steeper the gradient, the stronger the resulting wind, though the Coriolis effect and friction modify its direction and speed.

An apparent deflecting force caused by the Earth's rotation, turning moving air or water to the right in the Northern Hemisphere and to the left in the Southern. It is zero at the equator and strongest at the poles.

A theoretical wind that blows parallel to straight isobars when the pressure gradient force is exactly balanced by the Coriolis force. It approximates upper-air flow above the friction layer and underlies surface wind patterns.

A seasonal reversal of prevailing winds caused by unequal heating of land and sea, bringing a wet summer and dry winter to affected regions. The Indian monsoon is the classic example and dominates Odisha's rainfall year.

A narrow, fast band of westerly wind high in the troposphere, where strong temperature contrasts occur. The subtropical jet's position and the Tibetan anticyclone influence the onset and breaks of the Indian summer monsoon.

A line on a map joining places of equal rainfall over a stated period. Isohyet maps reveal rainfall gradients, rain-shadow areas and the tracks of monsoon depressions entering coastal Odisha.

The total mass of dissolved salts in seawater, usually expressed in parts per thousand. It depends on evaporation, precipitation, river inflow and mixing, and together with temperature controls seawater density.

The slow, global overturning of the ocean driven by differences in temperature and salinity, which control density. Cold, salty water sinks in high latitudes and returns as deep flow, regulating climate over centuries.

A large-scale, persistent movement of surface or deep seawater driven by winds, density differences and the Coriolis effect. Currents redistribute heat between latitudes and influence coastal climate and fisheries.

The average number of people per unit area, usually per square kilometre. It reveals crowding and pressure on land, but masks uneven distribution within a district or state.

The pattern in which people are spread across an area, shaped by relief, soil, water, climate, transport and economic opportunity. It is described as clustered, linear or dispersed rather than as a single average figure.

The number of females per 1,000 males in a population. It reflects social attitudes, health care and migration, and in India it is a key indicator of gender inequality in census reports.

The ratio of people outside working age, usually under 15 and over 64, to those of working age. A high ratio means a large dependent load on the working population and shapes demand for schools and health care.

A model describing the shift from high birth and death rates to low ones as a society develops. It passes through growth and slowing stages, and explains how a population pyramid changes shape over time.

A paired bar graph showing the number or share of males and females in each age group. Its shape reveals whether a population is young and growing, stable, or ageing and declining.

The rising share of a population living in towns and cities, driven by rural-to-urban migration and natural growth. It changes land use, creates slums and stresses water supply, drainage and waste management.

A natural resource that is replenished by natural processes within a human lifetime, such as solar energy, wind, flowing water, forests and fertile soil. Sustainable use must not exceed the rate of replenishment.

A resource formed over geological time and consumed faster than it is replaced, such as coal, petroleum, natural gas and most metallic ores. Once exhausted at a site, it cannot be restored there.

The exhaustion or serious reduction of a resource through overuse, wasteful extraction or loss of quality. It forces exploitation of poorer deposits, raises costs and can trigger migration or conflict.

Growing a planned sequence of different crops on the same field over successive seasons. It interrupts pest cycles, balances nutrient use and helps maintain soil structure and fertility.

A system where a farmer works a small holding very hard, using much labour and little machinery, mainly to feed the household. It is typical of monsoon Asia, including much of Odisha's rice land.

A system in which forest is cleared and burnt, the plot cropped for a few years, then abandoned as yields fall and fertility declines. It is practised in tribal uplands and is often called podu or jhum locally.

The choice of site for a factory, guided by access to raw materials, power, labour, transport, market and capital. Weight-losing industries such as iron and steel favour raw-material sites, while weight-gaining ones favour markets.

A manufacturing activity that is not strongly tied to raw materials or power and can locate flexibly, such as electronics assembly or software services. Transport costs are small relative to product value.

The tendency of an industry to remain at an established site even after the original advantages, such as local ore or cheap power, have disappeared. Skilled labour, sunk capital and supporting firms keep it in place.

A line on a topographic map joining points of equal height above a stated datum. The spacing of contours shows slope steepness, and their pattern reveals valleys, ridges, cliffs and plateaus.

The constant height difference between one contour and the next on a given map. A small interval gives detailed relief but many crowded lines; a large interval suits mountainous sheets.

A printed figure giving the exact elevation of a specific point, such as a hilltop or road junction, on a topographic map. It supplements contours where small features need precise heights.

The ratio of a cross-section's vertical scale to its horizontal scale. Because vertical scale is usually larger, slopes look steeper than they are, so the exaggeration must be stated when reading a profile.

A permanently marked point of known elevation, often fixed on a wall or pillar, used as a reference for levelling and surveying. It anchors local measurements to a national height datum.

The surveying operation of finding the height difference between points using a level instrument and graduated staff. Repeated readings are reduced to give elevations relative to a bench mark.

A graphical field method in which the map is drawn directly on a board mounted on a tripod, with sightings taken by alidade. It suits small areas and avoids later plotting of angles.

A hand-held magnetic instrument for measuring bearings of survey lines, read through a prism while sighting. It is light and quick but affected by local magnetic attraction and by magnetic declination.

The angle between magnetic north, shown by a compass needle, and true north. It varies with place and slowly with time, so it must be applied when converting field bearings to a map grid.

A line on a weather map joining places of equal atmospheric pressure, reduced to mean sea level. Close spacing means strong winds; the pattern of highs, lows and troughs guides weather forecasting.

The detachment and removal of topsoil by water, wind or tillage faster than it can form. It reduces fertility, silts reservoirs and, on steep deforested slopes, leads to gullying and landslides.

A soil and water conservation measure in which low earth ridges are built along contours to slow runoff and trap sediment on sloping fields. It reduces sheet erosion and improves moisture retention.

The planned use and protection of all land and water within a drainage basin, combining afforestation, check dams, contour works and cropping rules. It aims to regulate runoff, limit erosion and sustain local water supply.

The rapid downslope movement of rock, debris or earth when slope material loses strength. Heavy rain, deforestation, road cutting and earthquakes are common triggers in Odisha's Eastern Ghats.

The degree to which people, property or systems are likely to be harmed by a hazard, given their exposure, sensitivity and capacity to cope. It explains why the same cyclone harms different communities unequally.

A natural or human-made event or condition with the potential to cause harm, such as a cyclone, flood, drought or fire. It becomes a disaster only when it strikes a vulnerable, exposed population.

Policies and actions taken before a hazard strikes to reduce exposure and vulnerability and to strengthen coping capacity. Examples include early warning, cyclone shelters, land-use planning and community training.

Organised learning carried out in the real environment, where data on landforms, land use, settlement or traffic is collected, recorded and later analysed. It links classroom concepts to observed local conditions.

A set of written questions used to collect standardised information from respondents during a survey. Careful wording, ordering and pre-testing reduce bias and make responses comparable across households or shops.

Selecting a representative part of a population or area for study so that findings can be generalised. Random, systematic and stratified methods reduce bias, but the size and method must be reported.

A line or narrow belt across an area along which observations are recorded at intervals, often used to show changes in land use, vegetation or slope. It gives a systematic cross-section of field conditions.