page_title: Coastal reservoir
section_title: Construction
hierarchical_section_title: Coastal reservoir / Construction
caption_attribution_description: ગુજરાતી: સૂચિત ભરતીજન્ય વિદ્યુત યોજના
context_page_description: Coastal reservoir is a type of reservoir to store fresh water on sea coast area near a river delta. Saemanguem in South Korea, Marina Barrage in Singapore, Qingcaosha in China and Plover Cove in Hongkong, Delta Works in Netherlands, Thanneermukkom Bund in India etc. are a few existing coastal reservoirs.
context_section_description: The coastal reservoirs earth dikes extending up to 8 m msl high, is in the form of two parallel dikes separated by 1000 meters gap. The main purpose of the twin dikes is to prevent any sea water seepage into coastal reservoir as its water level is below the sea water level. The water level between the dikes is always maintained up to 1 m above the sea level by pumping fresh water from the coastal reservoir to the 1000 m gap between the dikes. The higher level fresh water barrier between the two dikes fully eliminate any sea water seepage in to the coastal reservoir by establishing fresh water seepage to the sea. The rain water falling on the coastal reservoir area and the run off water from the catchment area of its minor coastal rivers is adequate to cater the seepage and evaporation losses from the coastal reservoir. The 1000 m gap between the two dikes is also used as deep water mega harbor for shipping, ship breaking, ship building, safe berthing of crude oil, LPG, LNG, etc. ships with floating storage options, etc. For shipping purpose, the breakwater outer dike facing the sea is envisaged with few locks fitted with twin gates for access to the open sea. The top surface of inner dike would serve as access to the main land from the mega harbor with rail and road links. The coastal reservoir whose full reservoir water level (FRL) is at 0.0 m msl, would also drastically reduce the cyclone damage and flooding in  coastal areas. It would also greatly improve the irrigated coastal lands drainage. The dikes of coastal reservoirs would also reclaim coastal lands by giving protection from tsunamis, storm surges and tidal bores. The coastal reservoir area can also be used for locating floating solar power plants to generate the needed water pumping power. Also top surface of the inner dike of the coastal reservoirs can be used as transnational highways & railways. Coastal reservoirs are truly multi purpose infrastructure projects with  shipping & transport, land reclamation, irrigation, renewable power generation, etc. facilities.
  The dikes are built by dredging sand and clay from the nearby shallow sea bed using dredgers fueled by LNG or Hydrogen fuel cells or battery power to reduce the construction cost. Major river's water would be diverted in controlled manner to the coastal reservoirs from their delta channels or by flood flow canals by constructing barrages across the major rivers. Their excessive flood flows are directly routed to the sea. The coastal reservoirs located on either side of a major river course/path are interconnected by submarine ducts/pipes of suitable length. Wherever existing ports/waterways and famous beach resorts are to be preserved, the long coastal reservoir is broken in to parts and interconnected by submarine ducts of suitable length. During lean flow periods, minimum environmental flows would be maintained in medium and major rivers up to sea by letting water to the sea directly or via submarine ducts of suitable length. It would also prevent deterioration of water quality in coastal reservoirs by preventing inflow of inferior quality river waters with higher salt load. For inland shipping, the deep water ports (1000 m wide) would be connected with locks arrangement to the major rivers via delta channels and to the adjacent coastal reservoir. Fish migration to and fro to the sea or rivers is possible as the rivers are not completely blocked. Navigation paths from sea to the river via deep sea port will also serve as fish migration routs. However the negative aspects of these man made lagoons are to be evaluated in detail and proper remedial steps shall be incorporated to minimize the damage to coastal ecosystem by the presence of fresh water lagoon as barrier to the sea.
caption: Map of proposed Kalpasar Project coastal reservoir in India
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