Quantifying streamflow change caused by forest disturbance at a large spatial scale: A single watershed study

Abstract

[1] Climatic variability and forest disturbance are commonly recognized as two major drivers influencing streamflow change in large-scale forested watersheds. The greatest challenge in evaluating quantitative hydrological effects of forest disturbance is the removal of climatic effect on hydrology. In this paper, a method was designed to quantify respective contributions of large-scale forest disturbance and climatic variability on streamflow using the Willow River watershed (2860 km 2 ) located in the central part of British Columbia, Canada. Long-term (>50 years) data on hydrology, climate, and timber harvesting history represented by equivalent clear-cutting area (ECA) were available to discern climatic and forestry influences on streamflow by three steps. First, effective precipitation, an integrated climatic index, was generated by subtracting evapotranspiration from precipitation. Second, modified double mass curves were developed by plotting accumulated annual streamflow against annual effective precipitation, which presented a much clearer picture of the cumulative effects of forest disturbance on streamflow following removal of climatic influence. The average annual streamflow changes that were attributed to forest disturbances and climatic variability were then estimated to be +58.7 and −72.4 mm, respectively. The positive (increasing) and negative (decreasing) values in streamflow change indicated opposite change directions, which suggest an offsetting effect between forest disturbance and climatic variability in the study watershed. Finally, a multivariate Autoregressive Integrated Moving Average (ARIMA) model was generated to establish quantitative relationships between accumulated annual streamflow deviation attributed to forest disturbances and annual ECA. The model was then used to project streamflow change under various timber harvesting scenarios. The methodology can be effectively applied to any large-scale single watershed where long-term data (>50 years) are available.Citation: Wei, X., and M. Zhang (2010), Quantifying streamflow change caused by forest disturbance at a large spatial scale: A single watershed study, Water Resour. Res., 46, W12525,

Determining the hydrological responses to climate variability and land use/cover change in the Loess Plateau with the Budyko framework

“…Various methods have been developed to isolate hydrological impacts of land use/cover change from those of climate change (Wang et al, 2013;Wang, 2014;Ahn and Merwade, 2014), which can be classified into following types: (i) paired catchment approach (Brown et al, 2005); (ii) empirically statistical methods (Wei and Zhang, 2010;Zhang et al, 2011); (iii) physically-based hydrological models (Wang et al, 2013;López-Moreno et al, 2014;Serpa et al, 2015;Buendia et al, 2016); (iv) elasticity or sensitivity based method (Schaake, 1990;Sankarasubramanian et al, 2001;Arora, 2002;Roderick and Farquhar, 2011); (v) eco-hydrological approach (Tomer and Schilling, 2009);and (vi) decomposition method (Wang and Hejazi, 2011).…”

“…However, paired catchment studies generally involve small catchments and are expensive to conduct (Zhang et al, 2011). Empirically statistical methods such as regression modeling, time-trend analysis method (Zhang et al, 2011) and double mass curve method (Wei and Zhang, 2010) usually establish the relationships between precipitation and streamflow based on long-term historical data to detect the effects of climate change. These methods require long time series of data and generally lack physical meanings.…”

Topography significantly influencing low flows in snow-dominated watersheds

“…The watersheds are located between 51º N 122º W and 49º N 118º W in the Southern Interior of British Columbia, Canada where hydrological regimes are snow-dominated. In this region, the Pacific Decadal Oscillation shifted from a cool to a warm phase 85 around 1977 (Fleming et al, 2007;Wei and Zhang, 2010), resulting in more precipitation and lower temperatures, and consequently affecting flow regimes. In addition, an extensive mountain pine beetle infestation caused large scale forest cover change from 2003 onwards.…”

Quantifying the effects of climate change and human activities on runoff in the water source area of Beijing, China

“…Hence, it is important to detect and separate the effects of climate change and human activities and to determine the dominant factors which lead to runoff changes. Although several studies have recently been conducted on this topic (Lane et al 2005, Tuteja et al 2007, Li et al 2007, Wang et al 2009, Wei and Zhang, 2010, Zeng et al 2013, separating the effects of climate change and human activities in hydrology is still a challenge, and the impacts of the two factors on the water cycle still need further investigation at the local scale (Wang et al 2012).…”