Abstract
The runoff process in the Dongting Lake has been influenced by climate change and human activities in recent decades. To manage the Dongting Lake efficiently and exploit water resources properly under the background of water shortage, it is desired to detect the factors of runoff change in the Dongting Lake. Hydro-meteorological data from 1961 to 2019 are analyzed to reveal the climate change and runoff alteration of the Dongting Lake comprehensively. Mutation test is used to detect the change points of runoff depth series, finding that 1984 and 2005 are change points and therefore 1961–1983, 1984–2004, and 2005–2019 are regarded as baseline period (BP), period 1 (P1), and period 2 (P2), respectively. Eight methods are used to quantitatively assess the relative contribution of human activities and climate change on runoff variation. It reveals that climate change especially precipitation change plays the dominant role (climate change makes runoff depth increase 70.14–121.51 mm, human activities make runoff depth decrease 51.98–103.35 mm) in runoff alteration in P1 while human activities play a prime role (account for 88.47–93.17%) in P2. Human activities such as reservoir construction, water consumption, and land-use (land-cover) change may be the main factors that influence the runoff in the Dongting Lake in P2. According to the sensitivity analysis, runoff in the Dongting Lake is more sensitive to climate change in P2 compared with that in P1, and no matter in P1 or P2, runoff is more sensitive to change in precipitation than the change in potential evapotranspiration. Combined with climate forecast, the results of sensitivity analysis can be used to estimate runoff change caused by climate change in the future.
Highlights
Runoff, an important source of social water use, has changed in many regions of the world in recent decades [1]
According to the sensitivity analysis, runoff in the Dongting Lake is more sensitive to climate change in period 2 (P2) compared with that in period 1 (P1), and no matter in P1 or P2, runoff is more sensitive to change in precipitation than the change in potential evapotranspiration
Box plots are used to investigate the characteristics of those data in baseline period (BP), P1, and P2, which include Q1, Q2, Q3, minimum (Q1 − 1.5 × IQR, where IQR = Q3 − Q1), maximum (Q3 + 1.5 × IQR) and outliers (Figure 3b)
Summary
An important source of social water use, has changed in many regions of the world in recent decades [1]. There are four kinds of methods commonly used to separate the effects of human activities and climate change, namely empirical statistics, elasticity-based method, hydrological modeling, and conceptual model [8,9]. The most frequently used empirical statistics methods are the simple linear regression (SLR) method and the double-mass curve (DMC) method [10,11]. It requires long-time hydrological and meteorological data. The elasticity-based method was proposed by Schaake [12] It relays on the climate elasticity coefficients to represent the sensitivity of runoff to variations in meteorological factors, runoff
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