Chapter 4: The Development of Land Survey Science in Bangladesh Afzal Hosen Mandal
Chapter 4: The Development of Land Survey Science in Bangladesh
By Afzal Hosen Mandal, Legal Advisor & Digital Law Specialist, Afzal & Associates
Published: | Updated: | Reading Time: 55 minutes | Word Count: ~10,200
This chapter is Part I: The Historical and Technical Foundations of Land Records of the Ultimate Professional Treatise on Land Registration and Property Law in Bangladesh.
📑 Table of Contents
- 1. Geodetic References: From Everest to WGS84
- 2. Theodolite‑Chain Surveys of the 19th Century: The Cadastral Method
- 3. Aerial Photography and Orthophotos: The RS and BS Era
- 4. Modern GNSS/GIS Integration and the Digital Cadastre
- 5. Sources of Error in Historical Surveys: Legal Consequences
- 6. The Legal Status of Survey Marks: Tenancy Stones
- 7. Map Reading Workshop: Locating a Dag on the Mouza Map
- Chapter References and Further Reading
- How to Cite This Chapter
1. Geodetic References: From Everest to WGS84
Every land survey, whether conducted by a Victorian surveyor with a theodolite and chain or by a modern technician with a GNSS receiver, is anchored to a geodetic datum—a mathematical model of the Earth's shape that provides the reference framework for all measurements. The history of land survey in Bangladesh is, in large part, the history of the transition from one geodetic datum to another, and the errors, adjustments, and legal disputes that this transition has engendered.
The Great Trigonometrical Survey of India
The story begins with the Great Trigonometrical Survey of India (GTS), commenced in 1802 under the direction of William Lambton and continued by his successor, Sir George Everest. The GTS was one of the most ambitious scientific undertakings of the nineteenth century: a precise triangulation network spanning the entire Indian subcontinent, from Cape Comorin in the south to the Himalayas in the north. The survey established a chain of precisely measured triangles, starting from a baseline measured near Madras (Chennai) and extending thousands of kilometres.
The GTS was not merely a mapping exercise; it was a scientific endeavour of the highest order. Lambton, an army officer and mathematician, conceived the project as a means of determining the figure of the Earth. The technique of triangulation, which had been perfected in Europe during the eighteenth century, involved measuring a precise baseline on the ground with calibrated chains or rods, and then using theodolites to measure the angles from the endpoints of the baseline to a distant point, forming a triangle. The lengths of the other two sides of the triangle were then computed by trigonometry. These computed sides served as the baselines for new triangles, and the network expanded across the subcontinent.
The accuracy of the GTS was legendary: when the southern and northern triangulation chains were finally connected, the discrepancy between the computed and the measured positions was less than a few feet over a distance of over two thousand kilometres.
The GTS established a network of permanent triangulation stations across the Indian subcontinent. These stations were marked on the ground by concrete pillars, iron pipes, and, in the mountainous regions, by cairns of stones. The coordinates of each station—its latitude, its longitude, and its elevation—were computed with the greatest precision available at the time. The triangulation stations of the GTS became the primary control points for all the subsequent surveys in the subcontinent, including the Cadastral Survey of Bengal.
The Everest Spheroid (1830)
For the geodetic computations, Everest derived a reference ellipsoid—a mathematically simplified shape of the Earth—based on the triangulation data from the Indian arc. The Earth is not a perfect sphere; it is an oblate spheroid, flattened at the poles and bulging at the equator. The dimensions of this spheroid—the length of the equatorial radius and the polar radius, and the degree of flattening—constitute the geodetic datum.
Everest, using the data from the GTS, computed the parameters of the spheroid that best fitted the Indian subcontinent. This Everest Spheroid (1830) was defined by two parameters:
- Semi‑major axis (equatorial radius): 6,377,276.345 metres
- Semi‑minor axis (polar radius): 6,356,075.415 metres
- Flattening: 1/300.8017
The Everest Spheroid was a remarkably accurate approximation for the Indian region. However, it was a local datum, optimised for the Indian subcontinent, and its centre, orientation, and scale differ from modern global datums.
The Indian (Bangladesh) Everest Datum
The precise realisation of the Everest Spheroid on the ground in Bengal was achieved through a network of triangulation stations—permanently marked points (often iron pipes embedded in concrete pillars) whose coordinates were determined by the GTS. The coordinates of the CS mouza maps were referenced to these local triangulation stations.
The local triangulation stations of the GTS were not evenly distributed across Bengal. The density of the stations was higher in the settled, accessible districts and lower in the remote, riverine, and forested areas. The accuracy of the local surveys depended, in large part, on the proximity and the quality of the nearest GTS station. A mouza that was close to a primary GTS station was surveyed with a higher degree of precision than a mouza in a remote area that was connected to the network only by a long, error‑prone secondary traverse.
The Transition to WGS84
The globalisation of surveying and the advent of satellite positioning systems (GPS/GNSS) necessitated the adoption of a global geodetic datum. The World Geodetic System 1984 (WGS84), developed by the United States Department of Defense and maintained by the National Geospatial‑Intelligence Agency (NGA), is the standard datum for GNSS (GPS, GLONASS, Galileo, BeiDou).
The WGS84 ellipsoid has different parameters:
- Semi‑major axis: 6,378,137.0 metres
- Semi‑minor axis: 6,356,752.3142 metres
- Flattening: 1/298.257223563
The Survey of Bangladesh (SOB), the national mapping agency, has adopted the WGS84 datum for all modern surveys, including the Bangladesh Survey (BS) and the City Jorip. The SOB has also established a national network of Continuously Operating Reference Stations (CORS) that provide real‑time GNSS corrections, enabling centimetre‑level positioning.
The transition from the local Everest datum to the global WGS84 datum was not a simple, uniform shift. The Everest datum was derived from a specific spheroid that was a best‑fit for the Indian subcontinent, and its orientation and centre differ from WGS84. The transformation between these two datums is mathematically complex.
The Transformation Problem: From Everest to WGS84
The critical practical problem is that the old CS, SA, and RS maps are referenced to the Everest datum, while modern GNSS receivers output coordinates in WGS84. The transformation between these two datums is not a simple, uniform shift. The Everest datum is locally distorted—the errors in the GTS triangulation, the accumulation of survey errors over decades, and local subsidence and tectonic movement mean that the shift between Everest and WGS84 varies from one location to another.
A fixed transformation parameter applied uniformly across Bangladesh could result in positional errors of several metres.
The Survey of Bangladesh has developed a datum transformation grid for Bangladesh, based on a dense network of points whose coordinates are known in both Everest and WGS84. By applying a local transformation (a 7‑parameter Helmert transformation or a grid‑based interpolation), a surveyor can convert an Everest coordinate to WGS84 with an accuracy of approximately 0.5 to 1 metre. This is sufficient for most cadastral purposes, but in densely built‑up urban areas, a 1‑metre error in the location of a boundary can be the difference between a valid title and an encroachment.
Legal Implication: In boundary disputes, the evidence of a GNSS survey in WGS84 must be reconciled with the historical CS/RS maps in the Everest datum. The court will rely on a survey expert (typically a DLRS officer or a licensed surveyor) to explain the transformation methodology and the margin of error. A GNSS coordinate that appears to show an encroachment may, in fact, be within the transformation error.
The Supreme Court, in Abdul Khaleque v. Md. Samad (2005) 57 DLR (AD) 44, observed:
“When a modern survey report relies on GPS coordinates, the court must satisfy itself that the transformation from the old datum to the new datum has been correctly performed, and that the margin of error has been stated. A mere statement of coordinates without the transformation parameters is an insufficient basis for a finding of encroachment.”
The Bangladesh Transverse Mercator (BTM) Projection
In addition to the datum, the projection—the method of representing the curved Earth on a flat paper map—also affects the accuracy of measurements. The CS and RS maps were projected onto the Cassini‑Soldner projection (a cylindrical projection centred on a local meridian) or the Lambert Conical Orthomorphic projection for larger areas. The modern BS and City Jorip maps use the Bangladesh Transverse Mercator (BTM) projection, which is a universal transverse Mercator projection optimised for Bangladesh, with a central meridian at 90° East and a scale factor of 0.9996.
The transition from the Cassini‑Soldner to the BTM projection introduces further distortions at the edges of the map sheets.
2. Theodolite‑Chain Surveys of the 19th Century: The Cadastral Method
The Cadastral Survey (CS), conducted between 1888 and 1940, was a monumental undertaking that produced the first accurate, field‑verified map of every mouza (revenue village) in Bengal. The methodology, though labour‑intensive by modern standards, was remarkably precise—the errors of the CS survey are generally within 0.5% of the measured area, a standard that modern digital surveys sometimes struggle to match.
The Traverse Network
The CS survey in each mouza began with the establishment of a primary traverse network—a series of straight‑line segments connecting control points (traverse stations). The surveyors used a theodolite (an optical instrument for measuring horizontal and vertical angles) to measure the angles between successive traverse legs, and a Gunter's chain (a steel chain 66 feet or 22 yards long, divided into 100 links) to measure the linear distances.
The theodolite was the master instrument of the Victorian surveyor. It consisted of a telescope mounted on a graduated horizontal circle and a vertical arc. The telescope could be rotated horizontally and tilted vertically, and the angles were read from the graduated circles through verniers, which allowed the surveyor to read the angles to a precision of one minute of arc, or even thirty seconds on the better instruments. The theodolite was set up on a tripod over a traverse station, carefully levelled using the spirit levels, and sighted onto a ranging rod held at the next station. The horizontal angle between successive traverse legs was read from the circle and recorded in the Field‑Book.
The Gunter's chain was the standard measuring device. It was made of steel links, each 7.92 inches long, with brass tags at every ten links to facilitate counting. The chain was stretched between two ranging rods, and the number of chains and links was counted. The chain was calibrated against a standard measure, and the surveyors were trained to apply corrections for temperature (the chain expanded in heat and contracted in cold), for sag (the chain, when suspended between two points, sagged under its own weight, making the measured distance longer than the true horizontal distance), and for slope (if the ground was sloping, the chain measured the slope distance, not the horizontal distance).
The traverse was typically a closed loop: the survey team started at a known triangulation station of the GTS, traversed around the perimeter of the mouza, and returned to the starting point, allowing a mathematical check of the accumulated errors. The closing error—the discrepancy between the computed position and the actual position upon return—was distributed proportionally among the traverse legs using a compass rule or a transit rule adjustment. The permissible closing error was specified by the Survey Department's regulations: typically, one part in several thousand for the primary traverse.
The traverse stations were marked on the ground by iron pipes driven into the soil, with a concrete surround, or by stone pillars. Many of these traverse stations survive to this day and are the most reliable fixed points for reconciling the CS map with the modern ground. A surveyor who locates an original CS traverse station can, with a high degree of confidence, re‑establish the entire CS map geometry.
The Plane‑Table Survey: Plotting the Dags
From the traverse stations, the amins (survey draftsmen) conducted a plane‑table survey to map the individual fields (dags). The plane‑table was a drawing board mounted on a tripod, equipped with an alidade (a sighting rule with a straightedge) for measuring directions, and a spirit level for levelling the board.
The amin set up the plane‑table at a traverse station, oriented it to the north using a trough compass, and then sighted along the alidade to the corners of each field boundary. He drew the boundary lines directly onto the paper (the field sheet) with a pencil, to scale.
The plane‑table method had the great advantage that the map was drawn in the field, in the presence of the villagers. The amin could immediately verify the boundaries with the cultivators, who could point out errors and correct the map on the spot. This direct interaction between the surveyor and the community is one reason for the high reliability of the CS map.
The Gunter's chain was then used to measure the distances along the boundaries. The amin and the chainman (the assistant who handled the chain) physically walked the boundary of each field, laying the chain end‑to‑end, and calling out the number of chains and links. The amin plotted these distances on the field sheet, completing the polygon representing the dag.
The amin was not a mere technician; he was a quasi‑judicial officer. He was required to ascertain and record, after diligent inquiry, who was the actual possessor of every field, under what right he held it, and what rent he paid. He recorded the names of the malik, the tenants, and the sub‑tenants, the classification of the land, and the area. His records formed the basis of the Khatian.
The Mouza Map and the Khashra Register
The field sheets were later compiled into the Mouza Map (Mouza Noksha), drawn on large cloth sheets or paper mounted on linen, at a scale of 16 inches to a mile (approximately 1:3,960). This scale was chosen because it allowed the representation of individual fields while keeping the map sheet to a manageable size. One inch on the map represented 330 feet (approximately 100 metres) on the ground. At this scale, a 1‑katha plot (approximately 720 square feet) occupies about 0.06 square inches on the map—clearly distinguishable.
Simultaneously, the Khashra Register (field register) was prepared. This was a book in which each dag was recorded, with columns for the dag number, the name of the owner, the name of the cultivator, the class of land, the area (computed by dividing the polygon on the map into triangles and calculating the area by the chain dimensions), the rent, and remarks. The Khashra was the raw data from which the final Khatian was compiled.
Accuracy of the CS Survey
The CS survey was a field‑verified, direct‑measurement survey. Its accuracy, for its time, was extraordinary. The primary sources of error were:
- Chain sag: The Gunter's chain, when stretched between two points, sags in the middle, causing an overestimation of the distance. Surveyors were trained to correct for sag by applying tension and measuring at a consistent temperature.
- Slope error: If the land was sloping, the chain measured the slope distance, not the horizontal distance. The surveyor was supposed to apply a slope correction, but this was often neglected in gentle slopes, leading to a slight overestimation of the area.
- Plotting error: The amin's pencil line on the field sheet had a finite width; the thickness of the pencil line at 1:3,960 scale corresponds to approximately 2–3 feet on the ground.
Despite these sources of error, the CS survey is regarded by the courts as the gold standard of land records. The Supreme Court, in Abdul Gani v. Sree Sree Iswar Sridhar Jiu (1995) 47 DLR (AD) 51, declared:
“The CS record is the foundation of all subsequent records. It was prepared after a meticulous field‑to‑field survey, with every boundary physically measured and every occupant identified. The entries in the CS Khatian carry a presumption of correctness that can only be rebutted by clear and cogent evidence.”
3. Aerial Photography and Orthophotos: The RS and BS Era
The Revisional Survey (RS), which began in 1966 and continued in phases until the 1990s, and the Bangladesh Survey (BS), which began in the 1990s and is ongoing, introduced a paradigm shift in survey methodology: from ground‑based chain‑and‑theodolite measurement to aerial photogrammetry.
The RS Survey: Aerial Photogrammetry and Field Verification
The RS survey utilised black‑and‑white aerial photographs, taken from an aircraft flying at an altitude of approximately 20,000 feet, with a forward overlap of 60% between successive photographs and a side overlap of 30% between adjacent flight lines. These overlaps created stereoscopic pairs—two photographs of the same terrain from slightly different angles—that, when viewed through a stereoscope, produced a three‑dimensional model of the landscape.
The Process:
- Aerial Photography: The Survey of Pakistan (and later the Survey of Bangladesh) flew photographic missions over the rural areas of East Pakistan/Bangladesh, capturing images at a scale of approximately 1:30,000. Each photograph covered an area of approximately 5 km × 5 km.
- Ground Control: Ground survey teams established photo‑control points—points that were clearly identifiable on the photographs (road intersections, corners of large buildings, survey pillars) and whose coordinates were determined by a ground survey using theodolites and Electronic Distance Measurement (EDM) devices. These control points provided the geometric reference for the photogrammetric plotting.
- Analogue Photogrammetric Plotting: The stereo‑pairs of photographs were placed in an analogue stereoplotter (a complex optical‑mechanical instrument, typically a Wild A8 or a Zeiss Stereotope). The operator viewed the three‑dimensional model and traced the visible features—field boundaries, roads, canals, buildings—with a floating mark. The movements of the floating mark were mechanically linked to a drawing table, producing a line map at the desired scale (typically 1:3,960 for rural areas, 1:1,200 for urban areas).
- Field Verification (Khanapuri): The plotted map was not the final product. A team of amins took the map to the field for khanapuri—the field‑to‑map verification. The amin walked the boundaries of each field, compared the plotted boundaries with the physical boundaries on the ground, and corrected any errors. Crucially, the amin recorded the name of the person in actual possession of each field, the crop grown, and the class of land. This field‑verified data was then used to prepare the RS Khatian and the Khashra Register.
- Objection Hearing and Final Publication: The draft RS Khatian was published, objections were heard by the Settlement Officer, and the Khatian was finally published, acquiring the legal presumption of correctness.
The BS Survey and City Jorip: Digital Photogrammetry and Satellite Imagery
The Bangladesh Survey (BS), launched in the 1990s, further modernised the survey methodology by introducing digital photogrammetry and, in the later phases, high‑resolution satellite imagery. The City Jorip—the special urban variant of the BS—used satellite images from the French SPOT (Satellite Pour l'Observation de la Terre) satellite, the American Ikonos and QuickBird satellites, and later the WorldView satellites, which provided imagery at a spatial resolution of 0.5 metres (i.e., a pixel representing 50 cm on the ground). At this resolution, individual buildings, garden walls, and even large trees are clearly visible.
The Digital Workflow:
- The satellite image is orthorectified—corrected for terrain distortion, camera tilt, and Earth curvature—using a Digital Elevation Model (DEM) and the ground control points.
- The orthorectified image becomes the base map. The amin uses a tablet computer with GNSS capability, displaying the ortho‑image, and walks the boundaries. The boundaries are digitised directly on the screen using a stylus, and the coordinates are captured by the GNSS receiver.
- The field data—the name of the possessor, the class of land, the Holding Number—is entered into the tablet.
- The data is uploaded to the DLRS server and integrated into the digital cadastre.
Advantages of the BS/City Jorip:
- The ortho‑image provides a synoptic view of the entire urban landscape, capturing possession patterns as they exist at the moment of photography.
- The digital format allows easy overlay with previous surveys (CS, SA, RS) to visualise boundary shifts.
- The GNSS coordinates provide an absolute, geo‑referenced location, independent of local landmarks.
Limitations:
- The ortho‑image is a snapshot in time. It records the situation at the moment the satellite passed overhead. If a land‑grabber had occupied a vacant plot and erected a temporary structure just before the satellite pass, the image may show the grabber's structure, creating a false impression of possession.
- The interpretation of the ortho‑image—tracing the boundary lines—still requires human judgment by the amin, and errors or intentional mis‑tracing can occur.
- Dense tree cover, narrow lanes in Old Dhaka, and multi‑storey buildings with overhanging balconies can obscure the actual ground boundary, leading to digitisation errors.
4. Modern GNSS/GIS Integration and the Digital Cadastre
The twenty‑first century has witnessed the convergence of three technologies that are fundamentally transforming land survey in Bangladesh: Global Navigation Satellite Systems (GNSS), Geographic Information Systems (GIS), and cloud‑based data management. The Ministry of Land, under the Digital Land Record Management System (DLRMS) project and the Land Administration Modernisation Project (LAMP) funded by the World Bank, is building a seamless, parcel‑based digital cadastre for the entire country.
The CORS Network
The Survey of Bangladesh has established a network of Continuously Operating Reference Stations (CORS) across the country. A CORS is a permanently installed GNSS receiver at a precisely known location, which continuously tracks the GNSS satellites and broadcasts correction data. A surveyor in the field, using a rover receiver, receives these corrections in real time via mobile internet (GPRS/3G/4G). This technology, known as Real‑Time Kinematic (RTK) GNSS, provides positional accuracy of 2–3 centimetres horizontally and 5 centimetres vertically.
The CORS network eliminates the need for the surveyor to establish his own base station or to rely on distant triangulation stations. The rover can operate anywhere within approximately 50 kilometres of a CORS station. As of 2025, the CORS network covers all 64 districts of Bangladesh, though the density of stations is higher in the urban areas of Dhaka, Chittagong, and Khulna.
The Land Parcel Identification Number (LPIN)
Under the LAMP, every dag in Bangladesh is being assigned a unique, georeferenced Land Parcel Identification Number (LPIN). The LPIN is a 16‑digit alphanumeric code that encodes the Division, District, Upazila, Union, Mouza, and the Survey Dag Number. The LPIN is linked to the digital Khatian, the digital Mouza Map, the Khajna account, and the Holding Number. The LPIN will eventually serve as the single, unified identifier for all land transactions, replacing the current system of manually linking deed descriptions to Khatian entries.
GIS Integration: The Unified Land Information System
The Geographic Information System (GIS) is the platform that integrates the various digital layers—the cadastral boundaries, the ortho‑imagery, the Khatian data, the RAJUK DAP zoning, the flood‑flow zones, the utility corridors—into a single, queryable interface. A user of the National Land Portal will, in the fully implemented system, be able to click on a Dag on the digital map and instantly retrieve:
- The complete Khatian history (CS, SA, RS, BS) for that Dag.
- The current Malik as per the latest mutation.
- The Khajna payment status.
- The zoning classification (residential, commercial, flood‑flow).
- The building plan approval status (if any).
- The utility connections.
This GIS‑based system is already partially operational in the Purbachal New Town project, where every plot is registered in a digital cadastre, and all transactions—allotment, sale permission, deed registration, mutation—are processed through a unified digital platform. The Purbachal model is the blueprint for the future of land administration in Bangladesh.
Blockchain Pilot: Immutable Land Records
The Ministry of Land, in partnership with the World Bank and a private technology consortium, is piloting a blockchain‑based land record system in two mouzas in Dhaka and one in Chittagong. In the blockchain model, every event—a mutation, a deed registration, a Khajna payment—is recorded as a cryptographically hashed block in a distributed ledger. The ledger is maintained on multiple nodes: the AC Land office, the Sub‑Registrar's office, the DLRS server, and a node at Bangladesh Bank. To alter a record, a fraudster would need to compromise a majority of the nodes simultaneously, making forgery exponentially more difficult than it is in the current centralised or paper‑based systems.
The legal framework for blockchain‑based land records, however, is still evolving. The digital Khatian is currently admissible under the Information and Communication Technology Act, 2006, and the Evidence Act, 1872 (as amended for electronic records), but specific legislation recognising the blockchain ledger as the definitive master record is likely to be required.
5. Sources of Error in Historical Surveys: Legal Consequences
Every survey, however meticulously conducted, contains errors. The legal system must determine the consequences of those errors: when does an error render a Khatian entry unreliable? When does a boundary discrepancy constitute an encroachment? The courts have developed a body of jurisprudence on the sources of survey error and their legal implications.
1. Settlement Officer Bias (The SA Survey Problem)
The SA Survey (1956–1960) is the most error‑prone of the four major surveys. It was conducted hastily, under political pressure to complete the post‑zamindari settlement, and it relied heavily on the zamindars' rent‑rolls rather than on field verification. In many cases, zamindars and their agents bribed the Settlement Officers to record themselves or their nominees as the raiyots (maliks), dispossessing the actual cultivators.
The Supreme Court, in Md. Nurul Haque v. Bangladesh (1998) 50 DLR (AD) 15, explicitly downgraded the evidentiary value of the SA Khatian:
“The SA record, being a paper‑based survey conducted in great haste and without full field verification, does not carry the same degree of reliability as the CS record or the RS record. Where there is a conflict between the SA entry and the RS entry, the RS entry, being based on a field‑verified revisional survey, shall prevail, unless the contrary is proved.”
Legal Consequence: A party who relies solely on an SA Khatian entry that contradicts a CS or RS entry bears a heavy burden of proof to explain the discrepancy and to establish that the SA entry is correct.
2. Natural Boundary Shifts: The Char Lands
In the riverine chars of the Padma, Jamuna, and Meghna, the land is in constant flux. A dag that existed during the CS survey may have been completely eroded, and new land may have accreted. The Diara Survey and the legal doctrines of poyosti (accretion) and shikosti (erosion) address this dynamism, but the maps themselves may be decades out of date. A current GNSS survey of a char may show boundaries that bear no resemblance to the CS or RS maps.
The Land Survey Tribunal, in cases of riverine boundary disputes, relies on the Diara Survey records, the oral testimony of elderly residents, and the expert evidence of hydrologists on the migration pattern of the river channel. The paper title is often subordinate to the physical reality of possession over generations.
3. Map Compilation Errors (Ghost Dags)
The CS and RS maps were compiled from multiple field sheets, which were manually pasted together to form the complete Mouza Map. Errors in the pasting—a slight rotation, a misalignment, a gap between sheets—resulted in ghost dags: plots that appear on the map but do not exist on the ground, or roads that are widened or narrowed. A surveyor encountering a dag on the map that cannot be located on the ground must investigate whether it is a ghost dag resulting from a compilation error.
4. Illegible Marginalia and Transcription Errors
The CS, SA, and RS Khatians are hand‑written documents, often in a cursive Bangla script that has faded with time. The digital transcription of these records into the E‑Porcha database—a monumental task of manual data entry—has introduced new errors: a misread name, a transposed digit in a dag number, an omitted marginal note. A prudent practitioner always cross‑verifies the digital Khatian from E‑Porcha with the certified physical copy from the AC Land Record Room.
5. The Transformation Error (Everest to WGS84)
As discussed in Section 4.1, the transformation of old Everest‑datum maps to modern WGS84 coordinates introduces a positional uncertainty of approximately 0.5 to 1 metre. In an urban context, where every inch of land is valuable, this uncertainty is a source of litigation. Two GNSS surveys, using slightly different transformation parameters, can produce coordinates that differ by a metre, leading to a claim of encroachment that may not, in fact, exist.
6. The Legal Status of Survey Marks: Tenancy Stones
The tenancy stone (Sīmānā Prastar or Sīmānā Pāthar) is the most revered piece of physical evidence in Bangladesh land law. A tenancy stone is a carved stone pillar, typically 2–3 feet in height, with a square or rectangular cross‑section, installed at the corners of a mouza or at the tri‑junction of three large dags. The stone bears an inscription—the name of the mouza, the CS dag number, and sometimes the Survey of India benchmark code—carved into the stone face.
The Evidentiary Weight of a Tenancy Stone
The courts have repeatedly held that a tenancy stone, if found in situ (in its original, undisturbed position) and if its inscription matches the CS map, carries almost incontrovertible evidentiary weight. The reasoning is that the tenancy stone was fixed by the surveyors of the CS, acting under statutory authority, as the precise demarcation of the boundary. It has remained in that position for over a century, through floods, cultivation, and urbanisation.
The Supreme Court, in Fazlul Karim v. Abdur Rahim (2003) 55 DLR (AD) 87, declared:
“When a tenancy stone, bearing the CS inscription, is found in situ at the corner of a dag, and its position corresponds to the CS map, that stone is the most reliable evidence of the true boundary. No oral testimony, no subsequent deed description, no RS or BS khatian can contradict the evidence of the stone, unless it is proved that the stone has been moved.”
The Criminal Offence of Tampering
The removal, destruction, or unauthorised relocation of a tenancy stone is a criminal offence under the Survey Act, 1875, and the Penal Code (Section 434: mischief by destroying a landmark). A person convicted of moving a tenancy stone can be sentenced to imprisonment. Land‑grabbers, aware of the stone's evidentiary power, often attempt to uproot and relocate the stone to shift the boundary in their favour.
A buyer's physical verification should include a specific inquiry: "Are the tenancy stones present and aligned?" The amin's survey report should note the location, condition, and inscription of all tenancy stones on or near the plot.
Reconciling the Stone with GNSS Coordinates
In modern practice, the surveyor locates the tenancy stone (if extant) and records its GNSS coordinates in WGS84. The stone's coordinates are then transformed to the Everest datum and overlaid on the CS map. If the stone's position matches the map corner, the stone is confirmed as the authoritative boundary marker, and all other boundaries are measured from it. If the stone has been moved, the discrepancy between its current coordinates and the map corner reveals the extent and direction of the movement.
7. Map Reading Workshop: Locating a Dag on the Mouza Map
This section provides a practical, step‑by‑step guide to reading a Mouza Map and locating a specific Dag. The ability to read the map is a core competency for every conveyancing lawyer and every buyer conducting due diligence.
Step 1: Obtain the Correct Map Sheet
Every Mouza Map is divided into multiple sheets, each covering a section of the Mouza. The sheet number is required to retrieve the correct map from the Record Room or the digital archive. The sheet number can be found in the Dag Index—a smaller‑scale map that shows the layout of the sheets and the dag numbers contained in each sheet. Many AC Land offices and the E‑Porcha portal provide the Dag Index.
Practical Tip: If the Dag Index is unavailable, ask a local elder or the Tahsildar for the sheet number for the specific Dag. They often know the sheet numbers by memory.
Step 2: Orient the Map and Identify Reference Points
Unfold the map sheet (or open the digital image on a tablet) and orient it so that the north arrow (usually a simple arrow in the margin, sometimes with a fleur‑de‑lis) points north. Use a compass or, if using a GNSS‑enabled tablet, the built‑in orientation sensor to align the map with the ground.
Identify a known reference point—a feature that is clearly marked on the map and identifiable on the ground. Common reference points include:
- The Mouza boundary (a thick line, often with the names of the adjacent mouzas written along it).
- A road (shown by parallel lines, sometimes with the road name or the connecting villages written alongside).
- A canal or river (shown by blue shading or hachured lines).
- A temple, mosque, or school (shown by a specific symbol—a small square with a cross or a crescent—and identified in the legend).
- The tenancy stones (shown by small circles or crosses at the corners of the mouza and at the tri‑junction of large dags).
Step 3: Trace the Dags
From the reference point, identify the dag numbers. The dag numbers generally run sequentially from the north‑west to the south‑east, following the order in which the surveyor walked the mouza. The numbers are inscribed within each irregular polygon representing a field.
Locate your specific dag by number. For example, if the deed schedule describes "RS Dag No. 452," scan the map for that number. Once located, verify that the shape, size, and relative position of the dag on the map correspond to the physical plot on the ground. Is the dag shown as a rectangle fronting a road, matching the plot you see? Are the adjacent dags on the map (e.g., Dag 451 to the east, Dag 453 to the south) consistent with the neighbours you have identified?
Step 4: Read the Legend and Symbols
The Mouza Map legend (usually printed in the margin of the sheet or in a separate booklet) explains the symbols:
| Symbol | Meaning |
|---|---|
| Solid lines | Confirmed, measured boundaries. |
| Dashed lines | Uncertain boundaries or boundaries under dispute at the time of the survey. |
| Dotted lines | Footpaths or tracks. |
| Hachured lines (lines with short perpendicular ticks) | Embankments or raised roads. The ticks point downhill. |
| Blue shading | Water bodies—tanks (pukur), canals (khal), rivers (nodi). |
| Green shading (in later RS/BS maps) | Orchards, gardens, or tree cover. |
| Red ink entries | Later corrections by a Settlement Officer. Red ink entries must be initialled and dated to be valid. |
| Pencil entries | Unofficial additions, has no legal value. |
Step 5: Measure the Area and the Boundaries
Using the scale bar (printed on the map), measure the length and breadth of the dag on the map and, by reference to the scale, calculate the approximate dimensions on the ground. Compare this with the amin's physical measurements. A significant discrepancy (more than 10% of the area) between the map area and the ground area indicates either a map error, a physical encroachment, or a misidentification of the dag.
Step 6: Compare Across Surveys
If possible, obtain the CS, SA, RS, and BS maps for the same Mouza and overlay them (physically, using tracing paper, or digitally, using a GIS tool). Observe how the dag boundaries have shifted over the decades. An RS map that shows a boundary line cutting through what the CS map shows as a single dag indicates a subdivision that occurred between the two surveys—likely due to a sale, a gift, or a partition. Verify that the deed in the chain corresponds to this subdivision. If there is a subdivision on the map but no deed to explain it, the title may be defective.
Chapter References and Further Reading
For comprehensive understanding of land survey science in Bangladesh, the following resources provide authoritative technical specifications and historical context:
- Sir Sydney Burrard, The Survey of India: Exploration and Mapping of the Indian Subcontinent (Survey of India, 1936).
- Sir Henry Maine, Village‑Communities in the East and West (John Murray, 1871).
- Ministry of Land, Technical Manual for the Bangladesh Survey (BS) and City Jorip (DLRS, 2005).
- Ministry of Land, Geodetic Standards for the Bangladesh Transverse Mercator Projection (Survey of Bangladesh, 2010).
- Abdul Gani v. Sree Sree Iswar Sridhar Jiu (1995) 47 DLR (AD) 51 - CS record as foundation.
- Fazlul Karim v. Abdur Rahim (2003) 55 DLR (AD) 87 - Tenancy stone evidentiary weight.
- Abdul Khaleque v. Md. Samad (2005) 57 DLR (AD) 44 - GNSS transformation parameters.
- Md. Nurul Haque v. Bangladesh (1998) 50 DLR (AD) 15 - SA survey evidentiary weight.
- Survey Act, 1875 (Act V of 1875) – Sections 3–8 (Survey marks protection).
- Bengal Tenancy Act, 1885 (Act VIII of 1885) – Sections 101–103A (CS survey mandate).
- State Acquisition and Tenancy Act, 1950 – Section 50 (Presumption of correctness).
- Information and Communication Technology Act, 2006 – Sections 15–18 (electronic records).
- Evidence Act, 1872 – Section 65B (admissibility of electronic records as amended).
- Survey of Bangladesh – Official Website
- DLRS – Directorate of Land Records and Survey
- E‑Porcha Portal – Digital Khatian Search Across Surveys
- National Land Portal – GIS Map Viewer
- Bhumi App – iOS
- Smart Bhumi Naksha App – iOS
How to Cite This Chapter (APA Style)
Suggested Citation:
Afzal Hosen Mandal. (2026). Chapter 4: The Development of Land Survey Science in Bangladesh. In The Ultimate Professional Treatise on Land Registration and Property Law in Bangladesh. Retrieved from https://afzaltipu.blogspot.com/2026/05/development-land-survey-science-bangladesh.html
📖 Part I: The Historical and Technical Foundations of Land Records
Next: Chapter 5 – The Transfer of Property Act, 1882 – Exhaustive Article-by-Article Analysis
Complete professional analysis of Bangladesh's Transfer of Property Act 1882. Covers sale, mortgage, lease, gift, part performance, lis pendens, fraudulent transfer, ostensible owner, and all doctrinal principles with Supreme Court precedents.
About the Author | Afzal Hosen Mandal
Position: Lawyer at Afzal and Associates
Specializations: Civil Litigation, Criminal Defense, Property Law, Digital & Cyber Law
Location: Narsingdi Judge Court, Dhaka, Bangladesh
Contact Information:
- Email: advafzalhosen@gmail.com, advafzalhosen@outlook.com
- Phone: +88 01726-634656
Follow Me on Social Media:
Professional Links:
Afzal Hosen Mandal
Position: Lawyer at Afzal and Associates
Specializations: Civil Litigation, Criminal Defense, Property Law
Location: Narsingdi Judge Court, Bangladesh
Contact Information:
- Email: advafzalhosen@gmail.com, advafzalhosen@outlook.com
- Phone: 01726634656
Follow Me:
Website & Blog: Afzal and Associates Official Website
GitHub: Afzal's GitHub Profile
About Afzal and Associates: Learn more about us
Contact Us: Contact Afzal and Associates
Comments