Characterization and evaluation of hydrological processes responsible for spatiotemporal variation of surface water quality at Narmada estuarine region in Gujarat, India

Nirmal Kumar,Rita N Kumar,Pankaj Kumar,Ram Avtar,George Basil,Ali Kharrazi

doi:10.1007/s13201-014-0187-5

Abstract

This study is an effort to trace the spatiotemporal variation in water at Narmada estuarine region through solute concentration. A total of 72 water samples were collected and analyzed from three sampling points along with in situ measurement of tidal height at monthly basis for 2 years. Result shows that spatiotemporal variation of water quality occurs because of the following main mechanisms, i.e., carbonate weathering, dilution and seawater–freshwater mixing. Firstly, points situated toward inland showing the simple dilution effect on receiving high amount of monsoonal precipitation. Secondly, tidal fluctuation pattern has a strong influence on the water quality taken from the point located in near proximity to the coast. Finally, it can be concluded that water quality shows a different response, in accordance with the different tidal phase and the distance from the sea.

Highlights

Coastal zones, especially low-lying deltaic areas accommodate about 50 % of the world population, so it is very important to know hydrological processes at coastal aquifers
Result shows that spatiotemporal variation of water quality occurs because of the following main mechanisms, i.e., carbonate weathering, dilution and seawater–freshwater mixing
Tidal fluctuation pattern has a strong influence on the water quality taken from the point located in near proximity to the coast

Summary

Introduction

Especially low-lying deltaic areas (within 60 km of the shoreline) accommodate about 50 % of the world population, so it is very important to know hydrological processes at coastal aquifers. Estuaries are important coastal ecosystems which occur where there is a confluence of fresh and marine environments and create a salinity gradient from the inner to outer estuary (Prandle 2009). Cameron and Pritchard (1963) defined an estuary as a semi-enclosed coastal body of water which has free connection with the open sea and within which seawater is measurably diluted with freshwater derived from land drainage. Fairbridge (1980) defined it as an inlet of the sea reaching into a river valley as far as the upper limit of tidal rise, normally being divided into three sections: the upper estuary, dominated by freshwater; the middle estuary, an area dominated by brackish water deriving from a seawater and freshwater mixing; the lower estuary, maintaining free connection with the sea, composed by marine water. Excess nutrients are removed in bordering salt marshes, resulting in cleaner water for people and marine organisms

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Conclusion