The Effect of Runoff on Saltwater Intrusion in Weak Tide Estuary

Gao shiyou,Chen Rongli,Lu chen,X. Lei,Y. Yu,S. Cai,H. Li

doi:10.1051/matecconf/201824601097

Gao shiyou, Chen Rongli + Show 5 more

Open Access

https://doi.org/10.1051/matecconf/201824601097

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Abstract

Modaomen Estuary is a typical weak tidal estuary. The saltwater movement distance is not monotonic relationship with the tidal dynamics, it is also related to the strength of the salt wedge. In different phase of saltwater intrusion, saltwater intrusion distance has different responses to runoff. Through physical model tests, salt inhibition effect due to runoff at different stages had been studied. With the same total runoff in the half moon tidal cycle, methods of adjusting the amount of runoff distribution for better salt inhibition effect are proposed in the article. Increasing the runoff after neap tide can effectively inhibit the intrusion of saltwater.

Highlights

Modaomen Estuary is one of the main estuaries of the Pearl River
The problem of water supply blocked by salt water intrusion has become serious
Through a large number of prototype observations, the development process of salt water intrusion in Modaomen is revealed: the tidal dynamics is weakest during the neap tide period, and the stratification of salt and fresh water is most obvious; after the neap tide, with the increase of tidal dynamics and the increase of mixing, the salt in the bottom layer gradually diffuses to the surface layer, and at this stage the surface salinity increases while the bottom salinity decreases

Summary

Introduction

Modaomen Estuary is one of the main estuaries of the Pearl River. It is the source of water supply for Zhuhai, Macao, Zhongshan and other cities. The problem of water supply blocked by salt water intrusion has become serious. The water conservancy department restrains the salt water intrusion by dispatching the upstream reservoir to enlarge the runoff, increasing the water-intaking opportunity in the estuary area. As shown in Fig.[1], increasing the runoff at different stages of the saltwater intrusion will result in different effects of saltwater suppression. When to increase the runoff is more effective in restraining salt water intrusion and getting more water-intaking time is a quite realistic and complex problem, which is put forward in this paper

Mechanism of saltwater intrusion in the Modaomen Estuary

Model overview

Conclusion