The Puducherry district overall is a level peneplain with a normal height of 15 m above mean ocean level. The territory turns into a little undulating with conspicuous key positions fluctuating from 30 to 100m above the mean ocean level towards northwest and northeastern pieces of the locale. Three significant physiographic units are by and large noticed, viz., (I) Coastal plain, (ii) Alluvial plain and (iii) Uplands. 

The beach front plane reaches out as a restricted stretch for around 22 km and of four to 600-meter width on the eastern piece of the district along the Bay of Bengal. The significant piece of the seaside plain contains delicately inclining land with a chain of sand hills expanding up and down the coast. Other physiographic units which are normal for the waterfront fields, for example, spit bars, mud pads, tidal ponds and flowing channels, likewise happen. 

The alluvial plain, framed because of two significant waterways in particular Gingee and Ponnaiyar, overall is a repetitive plane with slant going from 1 to 3 percent. Other than the waterways and major trenches, there are miseries going about as capacity tanks, which are spread all around the territory to fill in as surface water repositories. 

The strategic positions are known as Uplands with heights of around 30 to 100m above the mean ocean level. These uplands which are famously known as "Les Montagnes Rouges" or the "Red Hills of Puducherry" are met by various chasms and profound gorges bringing about barren wasteland geography.


Soils in the space have been ordered into I) Red soil, ii) Black soil, iii) Alluvial soil and if) Colluvial soil. The significant part is covered by red soil of red sandy/earth topsoil type. Ferruginous red soils are additionally seen at places. Alluvial soils happen along the stream courses and the eastern piece of the seaside regions. Sandy beach front alluvium (arenaceous soil) is seen up and down the ocean coast as a thin belt.



Ground water happens in every one of the topographical developments going back in age from the Achaeans to the recent ones which can be extensively grouped into two hydrogeology units viz., (I) Fissured and broke translucent arrangements and (ii) Porous sedimentary arrangements.

Fissured Formation

Ground water for the most part happens under phreatic conditions in the endured mantle and under semi-restricted conditions in the fissured and cracked zones at more profound levels. The thickness of the endured zone in the area is in the scope of 2 to 12 m. The profundity of the wells went from 4.00 to 15.00 m bgl. 

The yield of enormous breadth wells tapping the endured mantle of glass as rocks goes from 100 to 500 lpm and can support siphoning for 2 to 6 hours out of each day. 

Permeable Formation

The permeable sedimentary developments happen in practically the whole locale and are addressed by the semi-united arrangements of Cretaceous and Tertiary and the unconsolidated Quaternary arrangements of recent age. Among the permeable sedimentary springs, the Vanur-Ramanathapuram Sandstone (Cretaceous) and the Cuddalore sandstone (Tertiary) springs and the shallow alluvial (Quaternary) springs comprise the three significant potential spring frameworks, in the locale. Ground water happens in these arrangements both submerged table just as under bound conditions and is being created through burrowed wells, burrowed cum-borewells and tube wells. 

The phreatic spring contains essentially of alluvial spring and in patches Tertiary and cretaceous springs are additionally found as a component of the phreatic spring. Tertiary spring is absent at all spots and, consequently, while drawing the piezometric surface shapes, just the region having the Tertiary spring has been thought of, and the equivalent has likewise been set apart in the guide. In the event of Cretaceous spring, a portion of the spaces have not been considered for improvement as the overlying Tertiary spring is profoundly potential. Thus, perception wells have additionally been set up just where cretaceous spring is being created as of now and consequently shaping of piezometric surface has been endeavored distinctly for such regions and the equivalent has been set apart on the guide.


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