Where does blue water go in the semi-arid area of northern China under changing environments?

L Ren,Y Liu,B Yong,X Yang,H Shen,F Yuan,M Ma,L Gong,S Jiang

doi:10.5194/piahs-364-88-2014

Abstract

Abstract. River flow regimes in the semi-arid region of northern China show a decreasing trend in terms of quantity. River runoff (i.e. blue water) reduction within the Laohahe catchment, the source area of the Liaohe River basin, manifests the aridity that exists widely in northern China. According to the water balance equation, during the past half-century, observed streamflow records in the Laohahe catchment show that blue water was re-directed to green water flow (i.e. evapotranspiration) over annual and decadal time scales, whereas precipitation did not vary much. Human activities and land-use/land-cover changes are the fundamental reasons for such runoff change. In the studied catchment, extensive land reclamation for agriculture, water withdrawal from streams, and abstraction from aquifers for irrigation are the direct and main causes leading to the decrease in observed blue water. These factors further demonstrate that a land-use decision is also a decision about water. Therefore, there is a need for an integrated modelling framework to intrinsically link climate, hydrological, and agricultural models with social and economic analyses.

Highlights

Runoff change can arise from the variations of precipitation, infiltration, evapotranspiration processes, etc
This paper aims to investigate the quantitative effect of human activities on river runoff and to account for the driving forces leading to blue water reduction under climate change and variability
The result of numerical experiments showed that Land-use and cover changes (LUCC) could cause green water or ET to increase by 0.95%, whereas blue water decreased by 8.71% in the Laohahe catchment (Liu et al 2009)

Summary

Introduction

Runoff (i.e. blue water) change can arise from the variations of precipitation, infiltration, evapotranspiration processes, etc. Contemporary environmental changes can positively (runoff increasing, Labat et al 2004, Gedney, et al 2006) or negatively (runoff decreasing, Ren et al 2002, Wang et al 2010) affect blue water. Worldwide continental runoff has increased throughout the 20th century (Labat et al 2004) despite more intensive human water consumption (Shiklomanov 2000). This is not the case in northern China (Ren et al 2002, Wang et al 2010) where less and less water flows in streams or rivers, and more and more water is contaminated. This paper aims to investigate the quantitative effect of human activities on river runoff and to account for the driving forces leading to blue water reduction under climate change and variability

Objectives

Findings

Conclusion