GroundWaterManic

Groundwater Exploration Groundwater conditions at a particular location can be described through its distribution of permeable layers: Such as sand, fractured rocks, and gravel, and impermeable layers, which are zones of low permeability such as clay, till, and solid rock. Image: Courtesy A contrast between the petrophysical properties of formations will give us a geophysical picture of these subsurface structures. The  mostly used petrophysical properties are: Seismic velocities : They are related to elastic properties & density. They define the speed with which various elastic deformations propagate through the materials.    Electrical conductivity : describes how easily electric current can flow through a medium when subjected to an applied electric field. Dielectric constant : This is a measure of the ability of a material to store electric energy. Electrical conductivity within rocks Within rocks and other materials, there are free electrical charges. When an electric field is

Geologic Structures  The structures found on the Earth make it possible to understand the dynamic nature of the Earth. It helps us know the forces that caused the upwelling and down-warping of the Earth. In a hydrogeological context, geologic boundaries and structures impact how water gets stored or flows within the Earth's surface. The development of these structures is influenced by the variation in the properties of the Earth's crust. Groundwater is usually stored in openings beneath the Earth. The openings can be in igneous, metamorphic or sedimentary environments. In hard rock domains such as igneous and metamorphic environments, geologic boundaries and structures are crucial when one is searching for groundwater resources. The proper siting of a water well in such an area will largely be determined by the correct mapping and location of these structures. Hard Rock Domains A hard rock domain is a geologic environment dominated by consolidated rocks. Such an area has metamo

Image Credit: Courtesy   As crucial as groundwater is, the resource is vulnerable and hence needs to be protected and managed. Groundwater is poorly understood and managed in many parts of the world despite its pivotal role in the sustenance of ecosystems and the provision of water supply. Understanding groundwater and its linkage with surface water and other members of the ecosystem is paramount to proper management of these resources. Studies have shown that some groundwater resources might have been accumulated eons ago and whereas there is increasing demand as a result of increasing population, chances are that these resources are no longer replenished. A system can be defined as a group of interrelated entities that form a unified whole. Groundwater systems can be defined as a system comprising the sub-surface water, geologic media containing the water, flow boundaries, sources, and sinks. These systems necessitate the storage and flow of groundwater within them. Groundwater syste

  Several methods can be used to estimate the hydraulic properties of aquifers. These can be in the laboratory and the field. The laboratory methods are not as expensive as field methods but the information obtained will not be a true representation of the formation.  The physical properties of geologic materials control the storativity and the ability of fluids to move through them. The hydraulic properties control the storage and transmission properties of aquifers. Porosity Porosity determines the volume of water that can be taken into or released out from storage by an aquifer. It is a function of the size, shape, and arrangement of the particles. Porosity can be defined as the percentage of rock that is void of material. The larger the pore spaces/the greater the number of pores the higher the porosity and the higher the water holding capacity of the aquifer. Porosity= Volume of void space/Total volume Factors affecting the magnitude of porosity Size, shape, and geometric arrangem

  Depending on the presence or absence of water table, an aquifer can either be classified as confined or unconfined. A special kind of aquifer known as leaky aquifer represents a combination of the two. A perched aquifer occurs where a groundwater body is separated from the main groundwater body by an impermeable layer of a limited extent. Unconfined aquifers These are aquifers whose upper surface of saturation zone is under the influence of the atmospheric pressure. The lower boundary is usually defined by a less permeable or impermeable layer. They are also known as  water table aquifers, free aquifers or phreatic aquifers .  Confined aquifers They are characterized by complete saturation, with the upper and lower layers being impermeable. They are not under direct influence of the atmospheric pressure since they are separated from the atmosphere by an impermeable stratum. Water in this aquifer imparts an upward hydrostatic pressure on the upper confining layer. Borewells tapping th

  Origin of groundwater Total water existing on earth is 13, 84,12,0000 cubic kms, out of which 8,00,0042 cubic kms is groundwater. Apart from this, 61,234 cubic kms is in form of soil moisture. Groundwater and soil moisture together constitute the sub-surface quantity of water. Groundwater mainly comes from three sources. They are,  Meteoric Water ’, which is the main source of groundwater and is received in the form of rain and snow;  Connate Water also known as "sediment water ," is water contained in pores and cavities of sedimentary rocks under seas and lakes. It is the second important source of groundwater.  Connate water is highly mineralized. Connate water is usually found deep down in the lower layers of the zone of saturation;  Magmatic Water  which converts into water after condensation of vapour as a result of volcanic action at the time of entering hot rocks. Apart from it, other sources are those in which groundwater becomes again available on the surface of th