Effects of the Three Gorges Project on Runoff and Related Benefits of the Key Regions along Main Branches of the Yangtze River

Yongqiang Zhang,Yanjun Gao

doi:10.3390/w11020269

Abstract

The Three Gorges Project (TGP) is the largest hydroelectric project in the world. It is crucial to understand the relationship between runoff regime changes and TGP’s full operation after 2009 in the Yangtze River Basin (YRB). This paper defines core, extended and buffer areas of YRB, analyzes the effects of TGP on runoff anomaly (RA), runoff variation (RV) and change of coefficient of variation (CCV) between two periods (2003–2008 and 2009–2016), takes percentage of runoff anomaly (PRA) as the evaluation standard, assures alleviation effect on severe dry and wet years of the research area, and finally summarizes related benefits of flood control from TGP. Our results indicate the inter-annual fluctuation of runoff in the core and extended areas expanded, but reduced in the buffer areas, and the frequencies of severe dry and wet years alleviated in the buffer, core and extended areas. Generally, the extended and core areas become less wet, and the buffer areas become less dry. The RV and CCV are both strengthened in the extended and core areas, but are weakened in the buffer areas, and RV is well positively correlated (R2 = 0.80) to CCV. Furthermore, the main benefits of TGP on flood control are remarkable in the reduction of disaster affected population, the decrease of agricultural disaster-damaged area, and the decline of direct economic loss. However, due to torrentially seasonal and non-seasonal precipitation, the sharp rebounds of three standards for Hubei and Anhui occurred in 2010 and 2016, and the percentage of agricultural damage area of five regions in the core and extended areas did not decline synchronously and performed irregularly. Our results suggest that the five key regions along the main branches of the Yangtze River should establish a flood control system and promote the connectivity of infrastructures at different levels to meet the significant functions of TGP. It is a great challenge for TGP operation to balance the benefits and conflicts among flood control, power generation and water resources supply in the future.

Highlights

Water is one of the most significant resources for a country’s social, economic and environmental development, and most nations are facing different degrees of floods and drought threats caused by the imbalance of water distribution in the world [1]
After the full operation of Three Gorges Project (TGP) with 175 m height impoundment in 2009, an enormous flowing reseRVoir of the river-channel type crossing Chongqing and Hubei was formed with a general area of 1084 km2
When comparing 2003–2008 to 2009–2016, runoff anomaly (RA) expanded in the core and extended areas but converged in the buffer areas, and the amplification extent was higher in the extended areas than that in the core areas

Summary

Introduction

Water is one of the most significant resources for a country’s social, economic and environmental development, and most nations are facing different degrees of floods and drought threats caused by the imbalance of water distribution in the world [1]. Water 2019, 11, 269 increasingly emerged because of the potential and comprehensive impacts They basically include enormous environmental changes of habitats inundation and fragmentation, extinction of local species of plants and fishes, ugly landscapes of water level fluctuation zone, sedimentation accumulation and capacity decrease of reseRVoir and regional climate changes, the apparent economic impacts of loss of old industries and enterprises and shortages of new ones, depressed livelihood of involuntary resettlement, high unemployment rates, infertile farmland located far away from economic centers, and the continuous social uncertainties of loss of unique historical and cultural heritage, spiritual sustenance and cultural integration of migration [2,3,4,5,6,7]. The case study of Nestos River (Greece) indicated the sedimentation effect of construction and operation of two reseRVoirs (Thisavros and Platanovrysi) to coastal erosion, the sharp sediments decrease impacted sediments supply to basin outlet of river delta, the neighboring coast and the coastal morphology, which even inversed the erosion/accretion balance in the deltaic as well as the adjacent shorelines, from accretion predominated erosion to erosion predominates accretion, just within five years after the reseRVoirs’ construction [8,9]

Methods

Results

Conclusion