Journal of Sustainable Urbanization, Planning and Progress

Next to air, fresh water has been always considered as the most important resource, central to economic development as well as to human physiological needs. Currently the total world population is about 7 billion, and, by 2050, it is projected to be 9 billion. By that time an additional 40 Nile Rivers will be needed. Historically, inland dams have successfully solved the water deficit problems in many places, but more and more countries are resorting to emerging technologies like desalination, wastewater recycling and rainwater tanks which are needed to replace inland dams for a number of geomorphological, environmental and societal reasons. These new technologies require a paradigm shift in the water supply industry: global water consumption is only 5~6% of annual runoff—as it is in Australia—so the coming shortage is not of water, but of storage.

Water is essential for the global population's domestic, agricultural and industrial purposes. Water shortage and its associated issues are projected to worsen with the population growth. Among many innovative solutions, coastal reservoir (CR) may be one of the feasible solutions. Many CRs have been constructed around the world. It is necessary to systematically analyze the environmental/social impacts of these coastal reservoirs, and the results should be compared with other solutions like desalination plants, wastewater treatment and reuse, dams, reservoirs, inter-basin water diversion and rainwater tanks etc. The world largest scientific database “Web of Science” and “google imagine” have been used as a tool for comparison. The results show that coastal reservoirs can be socially beneficial and have the potential to increase tourism within a region and thus hold economic value for communities. Good practice, policy and care can ensure the feasibility of coastal reservoirs as a future fresh water resource.

China is a water-rich country in terms of rainfall and rivers size, but its urbanization mainly occurs in the eastern coastal cities. The densely populated coastal cities intensify the water stress. To seal the gap between water demand and supply, many ways have been tested like water diversion projects, desalination plants and wastewater recycling plants etc. Different from these solutions, this paper discusses the strategy of coastal reservoirs in China’s coastal cities. Its feasibility of using the available water is investigated and its water quality can be ensured if the 2nd generation coastal reservoirs are applied. The results show that the water shortage problems in China coastal cities can be well solved if CRs are applied.

The paper presents the feasibility study on the formation of fresh water reservoir and impounding the surface runoff in a typical brackish water lake of southern India, Ashtamudi Lake for urban water survival of Coastal town, Kollam, India. The concept envisages of building a barrage at the outlet of Ashtamudi Lake at the mouth of the Arabian Sea to serve the purpose of preventing seawater intrusion into the lake, avoiding the contamination of the freshwater supply from sea water. To validate the concept, it is proposed to conduct a feasibility study which addresses the concerns about the availability of runoff from Kallada River. The paper also presents possible schemes for storing fresh water within Ashtamudi Lake by constructing dikes at appropriate locations. The length of dike and the volume of water that can be stored with proposed schemes are outlined in the paper.

This paper addresses the feasibility of creating a fresh water reservoir in the Arabian sea impounding the flood waters from Netravathi river. The project schemes comprises mainly two steps first the construction of the dyke in the Arabian Sea, and second the process of natural replacement of salty water by rainwater and surface runoff to the reservoir. The study presents the detailed hydrological analysis of Netravati and Gurupura rivers including estimation of runoff into the sea.The study estimates the surface runoff at inlet and outlets of Netravati basin along the costal lines of Arabian Sea. The existing Land use along the costal lines of Netravati basin is assessed.  The dyke must be designed to separate fresh water from the salty waters of the Arabian Sea considering the tidal variations and wave heights. The bathymetric profiles of the sea bed has been created and presented in the paper. The annual runoff at the mouth of Netravati River was estimated as 388 TMC and just 2.5% of this would be sufficient to meet the present water shortfall of Bengaluru and Mangaluru. The annual sediment load was found to be negligible. The water quality parameters are well within permissible limits ensuring quality water from Netravathi to the proposed coastal reservoir.

Caofeidian freshwater reservoir is nearly to the lower reaches of Shuanglong River area, which is located on the coast of Bohai Sea. However, the two sides of the Shuanglong River are the agricultural production and cultivation and aquaculture areas, that resulting in serious agricultural non-point source pollution. In this paper, we introduce a water purification pattern of freshwater reservoir based on floodplain wetland and ecological ditch. We set up floodplain wetlands to purify water with Shuanglong River floodplain and the reservoir surrounding idle beach, and lay out ecological ditch to purify rice paddy fields drainage with rice paddy ditch. Calculated, the water purification system of floodplain wetland could reduce the storage of pollutants, including 450 tons of COD, 18 tons of total nitrogen, 3.6 tons of total phosphorus annually, and reduce the water evaporation of 14,000 m³ annually. Paddy field ecological ditch strengthen the water purification pattern, can effectively remove the storage of pollutants with 4 tons of total nitrogen, 0.8 tons of total phosphorus annually, and conserve 1,000 m³ water nearly. It could improve the water quality of the storage river by the water purification pattern of Caofeidian freshwater reservoir, which also has environmental and economic benefits and provide inspiration for the construction of similar freshwater reservoirs.

India is a sub-continent where presently 320 million people remain in the water-starved parts of the country and according to the UN, this number is expected to increase to 840 million in the year 2050. There is a severe demand-supply mismatch. Though there has been no significant change in India’s rainfall pattern, the number of areas under drought in India is increasing every year. Increase in population is one of the reasons for water scarcity but the inefficient management of the received precipitation stands as the major cause. Though extreme rainfall events are significantly increasing, there is a spatial non-uniformity in the rainfall events that occur. This makes it difficult to pre-plan large scale water storage at different locations. Out of the 4,000 billion m³ of freshwater available from precipitation per annum, major portion run off into the sea. The solution to India’s water problem is to conserve the abundant monsoon water bounty, store it in coastal reservoirs, and use this water in areas which have occasional inadequate rainfall or are known to be drought-prone or in those times of the year when water supplies become scarce. It is estimated that about 4,400 thousand million cubic feet of rainwater just simply drains into the sea. This paper focuses on the concept of Coastal Reservoir. This basically means building a storage structure near the mouth of river. In this way, the amount of water that is wasted as run-off can be stored. The construction of a coastal reservoir does not involve many risk factors and disadvantages like relocation which would occur in an inland dam construction. The paper also presents the concept of Sarovarmala - a chain of coastal reservoirs which is an innovative concept that has the potential to ensure water availability to India throughout the year.