Analytical Solution for Solute Transport Modeling along the Unsteady Groundwater Flow in Porous Medium

The Chhattisgarh state covers a total geographical area of about 135192 Sq. Km with subtropical climate, characterized by extreme summer and moderate winter having average rainfall of about 1300 mm. Physiographically, the area is characterized by three distinct landforms namely Bastar plateau in the South, the plain of Mahanadi river and its tributaries in the central part and the hills of Chhotanagpur plateau in the northern region. The major river basins in the state are Brahmani, Godavari, Ganga, Mahanadi and Narmada . The total catchment of these river basins is about 13559 kilometers. The Mahanadi Basin is the largest basin covering an area of about 76150 square kilometers out of 141589 square kilometers, nearly 4.3 percent of total geographical area of the country. Chhattisgarh has 2 percent population and 3.2 percent of total surface water resources of the country. The utilizable surface potential in the state if properly harnessed can irrigate about 4.3 million hectares area against the existing potential of 1.38 million hectare. Due to various anthropogenic activities, urbanization, industrialization etc, the quality and quantity of water have been adversely affected. The rivers Hasdeo, Indravati, Kharun, Apra etc. are polluted due to industrialization and urbanization in various parts of the Chhattisgarh. To check the pollution, proper management of solid/liquid waste of various industries is needed. Beside these, use of biofertilizers instead of chemical fertilizers, pesticides etc should be promoted. Effective water management strategies combined with watershed treatments like soil conservation, afforestation, desilting of rivers, rainwater harvesting etc are needed to maintain the health of the river basins of Chhattisgarh. The Jal Shakti Abhiyan started by the Government of India is a highly welcome move in this direction.

Palghar, Thane, Raigad, Ratnagiri, Sindhudurg and Greater Mumbai districts of Maharashtra form the Konkan Coastal belt of Maharashtra. In the coastal areas the immediate effect of high groundwater development is often sea water intrusion. Although there were sporadic studies by earlier workers (Umrikar et al., 2007, Gupta et al. 2010) into some reported isolated cases of seawater intrusion in the coastal areas, this has been a maiden attempt to decipher the extent of seawater intrusion in the entire coastal tract of Maharashtra.The area is underlain by Dharwarian meta-sediments (Lower Precambrian age), Deccan Trap lava flows (Upper Cretaceous to Lower Eocene age), Laterites (Pleistocene age) and Coastal alluvial deposits (Recent to Sub-Recent age). Groundwater occurs under phreatic condition in the Coastal and riverine alluvium, laterites and weathered/fractured rocks. The area has been covered by systematic hydrogeological surveys, reappraisal Surveys and groundwater monitoring by CGWB. in these formations depth to water levels range from 0.6 m bgl to 8.07 m bgl. Groundwater is mildly alkaline with pH range of 6.9 to 9.0. Electrical conductivity ranges from 61 to 29370 ?S/cm at 25?C. Only two Samples from Dapoli in Raigad district show EC values higher than 3000 ?S/cm at 25?C. In general, water quality is good and suitable for domestic use and irrigation. In order to confirm the sea water intrusion, ionic ratios like Na:Cl, and Cl:CO3 + HCO3, were computed. From the analysis it is found that about 2 to 10 km wide coastal belt and the inland tidal backwaters are affected by salinity intrusion. It is revealed that about 55% of the analysed samples have indicated salinity ingress. The extent of sea water intrusion is more in the southern part progressively diminishing towards northern area. The maximum effect is observed in Sindhudurg district followed by Ratnagiri, Raigad, Palghar and Greater Mumbai.Over-exploitation of groundwater in pockets and diminishing seaward freshwater flow in the rivers are the major reasons for sea water ingression. Regulation of groundwater development in the coastal area and areas adjacent to estuaries, maintaining adequate stream flow, stopping of riverbed sand mining, construction of tidal regulators at suitable places and creation of fresh water barrier through rainwater harvesting and groundwater recharge are essential to control further sea water intrusion in the area.

Surface water resources in Rajasthan are scarce and scanty owing to hot arid climatic conditions. Major parts of western Rajasthan are devoid of any major drainage system and are reeled under spells of chronic droughts. Average annual rainfall in the state is of the tune of 540mm, decreases westward and is even less than 150mm in the western most parts of Jaisalmer district. Annual Potential evapo-transpiration is also as high as 2060mm in parts of Jaisalmer district. There are 15 river basins in the state. There are also numerous natural as well as artificial freshwater lakes including Pushkar, Rajsamand, Nakki, Ana Sagar, Kayalana, Ramgarh, Foy Sagar etc. mainly in the southern and eastern parts of the state. Salt lakes include Sambhar, Kuchaman, Pachpadra, Didwana, Phalodi, Lunkaransar etc. Indira Gandhi Nahar (IGNP), Bhakara and Gang canals have been constructed to bring Himalayan water to the desert areas of western Rajasthan in addition to other major commands of Chambal, Mahi and Narmada canals etc. In Rajasthan, irrigation projects completed include 22 Major projects, 77 Medium projects, 660 Minor projects and 3139 Tanks have been transferred to Panchyat Raj Department. Usable water is of the magnitude of 16.05 BCM and the Gross Storage Capacity created is of the order of 14.547 BCM. The Live Storage Capacity created is about 11.99 BCM. Out of the total allocated share of 17.88 BCM under interstate water agreement, average annual water availability remains 12.66 BCM due to various climatic, political, institutional or hydrological reasons. In addition to various Central Government Schemes, Watershed schemes and Mukhyamantri Jal Swavlamban Abhiyan are also implemented in the state.

The high reliability of rural and urban settlements on groundwater in India and the individualistic nature of groundwater usage make groundwater management and governance extremely challenging. Groundwater resources development in India, even today, has progressively become synonymous with increasing the accessibility of the resource through more and more sources and meeting the growing demand through the infrastructure of distribution. Management of groundwater becomes selflimiting when the focus is on exploration for new sources, without understanding resource behaviour. On the other hand, experience has shown that bringing aquifers to the centre stage of groundwater management is important. The concept of aquifers changes the way in which communities begin to perceive groundwater and becomes the first step in developing socioecological resilience to groundwater-related vulnerability. Building resilience to groundwater-related vulnerability further includes developing a governance mechanism that strikes a balance between supply management and demand regulation through an understanding of the resource, i.e., the aquifer.Aquifer systems in India are highly diverse and complex because of the variation in their inherent properties such as storativity, transmissivity and groundwater quality. Aquifer vulnerability is a consequence of not only how the rampant exploitation and contamination of groundwater occur, but also how different aquifers react to these fluxes. Moreover, irrespective of the scales of groundwater accumulation and movement, micro-level analysis of aquifers becomes imperative because of the atomistic nature of groundwater access and use. A systematic hydrogeology-based approach that requires delineating aquifers, understanding the dynamics of groundwater and mapping the demand and dependence of community on the resource holds the key to decentralized groundwater governance in India. Such an approach can be undertaken through participatory monitoring, decision support and action.The inherently heterogeneous nature of aquifers and communities in western and central India demand a strategic application of mapping, characterizing and managing local aquifers through a participatory groundwater management protocol. This nuanced approach beginning with aquifers as both a resource and a system, ensures equitable, efficient and hence, the sustainable management and governance of aquifers in this region.

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