Sensitivity of the land surface hydrological cycle to human activities in China

Abstract

While many studies have focused on the sensitivity of the water cycle to climate change, few have investigated this sensitivity to human activities. We don't know how sensitive the surface hydrological system is to human activity and which component of the water balance is most sensitive. This study performed model simulations to quantify the sensitivity of China’s land surface water cycle to the human activity intensity (HAI). The results indicate that lateral flow to streamflow (LATQ) was the most sensitive to HAI (0.679), followed by base flow (GW, 0.291), actual evapotranspiration (ET, 0.203), and surface runoff (SURQ, 0.174), while the percolation amount (PERC) and water yield (WYLD) sensitivities were 0.172 and 0.081, respectively. Hotspots of the ET sensitivity to HAI occurred mainly in Western and Northeast China. The spatial sensitivity patterns of GW and PERC were similar, i.e., lower in the south than elsewhere. Notably, SURQ was insensitive to HAI changes in the urban areas of South China (sensitivity: 0–0.06). Although the HAI variation was the lowest in semiarid regions during 1980–2018 (0.07–0.82%), their water cycle sensitivity to HAI was the highest among all four climatic zones. The ET, SURQ, LATQ, PERC, GW and WYLD sensitivity coefficients to the HAI in the semiarid zone were 20.441, 41.292, 5.276, 24.431, 52.06 and 1.032, respectively. Hydrologically, semiarid areas, the Qinghai-Tibet Plateau and the region near the Karamay oilfield should be prioritized. Specifically, LATQ should receive the most attention.