The role of human activities in the weakening of the propagation relationship between meteorological and hydrological droughts in the Heihe River Basin

Abstract

Meteorological droughts could propagate into hydrological droughts and cause agricultural and societal damage. However, the quantitative impact of human activities on the drought propagation has not been well understood. Based on the precipitation and streamflow observational data and hydrological model simulations during 1961-2013, this study analysed the drought propagation characteristics and quantified the impact of human activities on the propagation in the upper and middle reaches of Heihe River Basin. The matched meteorological and hydrological drought events indicated that the drought propagation was characterized by a lagged onset, weakened drought severity and reduced development and recovery speeds. In the upstream area, the correlations between meteorological and hydrological droughts were significant, and human activities had a negligible impact on the drought propagation. In contrast, the impact from human activities was significant in the midstream area, and the effect was two-fold. Specifically, human activities (e.g., reservoir regulation) reduced the propagation probability of one or several meteorological droughts propagating into a hydrological drought by 16%. Meanwhile, human activities had remarkable effects on long-lasting and extreme hydrological droughts through reducing their duration and severity by 18% and 37% respectively. On the other hand, the occurrence probability of mismatched drought events, that is, meteorological droughts without causing hydrological droughts and hydrological droughts without preceding meteorological droughts, increased by 34% due to human interventions.Human activities also accelerated the development speed of slowly developing hydrological droughts. In addition, human activities increased the mean duration and severity of moderate hydrological droughts by 32% and 18%. The results are expected to provide scientific bases for understanding the formation and development process of hydrological drought and improving drought forecasting under global change.

Drought propagation across meteorological, hydrological and agricultural systems in the Lancang‐Mekong River Basin

“…Drought is divided into three grades by $$$ \mathrm{SPI} $$$ or $$$ \mathrm{SRI} $$$ value in this paper, as follows: (a) no drought, with $$$ \mathrm{SPI}\ \mathrm{or}\ \mathrm{SRI}>-1 $$$; (b) moderate droughts, with $$$ -1.5<\mathrm{SPI}\ \mathrm{or}\ \mathrm{SRI}\le -1 $$$; (c) severe droughts, with $$$ \mathrm{SPI}\ \mathrm{or}\ \mathrm{SRI}\le -1.5 $$$; The run theory method is used to identify drought events (Wu et al, 2021; Yang et al, 2023). Specifically, $$$ {\mathrm{SPI}}_0\ \mathrm{or}\ {\mathrm{SRI}}_0=-1 $$$ is defined as the threshold for drought event that is, $$$ \mathrm{SPI}<{\mathrm{SPI}}_0\ \mathrm{or}\ \mathrm{SRI}<{\mathrm{SRI}}_0 $$$, is recorded as a drought, and the drought severity in duration $$$ t $$$ is characterized by $$$ \left|{\mathrm{SPI}}_t-{\mathrm{SPI}}_0\right| $$$ (or $$$ \left|{\mathrm{SRI}}_t-{\mathrm{SRI}}_0\right| $$$).…”

“…Drought is divided into three grades by SPI or SRI value in this paper, as follows: (a) no drought, with SPI or SRI > À 1; (b) moderate droughts, with À1:5 < SPI or SRI ≤ À 1; (c) severe droughts, with SPI or SRI ≤ À 1:5; The run theory method is used to identify drought events (Wu et al, 2021;Yang et al, 2023). Specifically, SPI 0 or SRI 0 ¼ À1 is defined as the threshold for drought event that is, SPI < SPI 0 or SRI < SRI 0 , is recorded as a drought, and the drought severity in duration t is characterized by SPI t À SPI 0 j j(or SRI t À SRI 0 j j ).…”

“…Massive water abstraction under population expansion and economic development aggravates hydrological drought occurring worldwide (Van Loon et al, 2022), whereas various engineering and non‐engineering measures also provide opportunities for drought mitigation. As mentioned in this paper, artificially altering the discharge through reservoir operation can alleviate hydrological and agricultural droughts during dry periods; also, this engineering measure is practiced in many large‐scale basins, such as the Heihe River (Yang et al, 2023) and the Yangtze River (Huang et al, 2021). Moreover, some non‐engineering measures, such as water and soil conservation and drought insurance (Cremades et al, 2018; Zeff & Characklis, 2013), may also have a positive effect on coping with drought.…”

“…In addition, building dams is another measure taken to alleviate drought, but their operation alters the natural flow process, as well as impacts the hydrological drought process (Huang et al, 2021). Such anthropogenic disturbances interfere with the drought propagation process and feedback to the natural system (Yang et al, 2023). Furthermore, human water-related activities occurring upstream may affect downstream drought conditions, leading to spatially variable responses.…”

Vegetation Greening and Climate Warming Increased the Propagation Risk From Meteorological Drought to Soil Drought at Subseasonal Timescales

“…To date, numerous studies have investigated the drought propagation characteristics at watershed, national and global scales (Huang et al., 2017; Q. Li et al., 2022; Ma et al., 2019, 2023; Shi et al., 2022; Xu et al., 2019; Yang et al., 2023; Zhou et al., 2021). Van Loon (2015) stated that the onsets of agricultural and hydrological droughts were usually later than that of meteorological drought, and concluded that the drought propagation could be characterized by pooling, lagging, attenuation and lengthening.…”