Assessment of the Flow Regime Alterations in the Juma River, China

River flow regimes are considered to be primary drivers of riverine ecosystems, and have played a decisive role in sustaining the integrity, biodiversity and stability of the riverine ecosystem. The aim of this study was to explore the changes of hydrological regimes and obtain the suitable flow regimes for maintaining the health of ecosystem. The changes of flow regimes were investigated by the Mann-Kendall test, Indicators of Hydrologic Alteration (IHA) and Range of Variability Approach (RVA) at annual and daily scale in the Juma River, respectively. Results showed that: (i) the annual flow presented a downward abrupt in 1981 at Zijingguan station and after that the flow magnitude was smaller in general; (ii) during the post-impact period, both of the maximum and minimum flow magnitudes for 1-day, 3-day, 7-day, 30-day, and 90-day declined, and the degree of variation almost all stayed in low and moderate status; (iii) the number and duration of high pulse decreased for the post-impact period, whereas those for low pulse extended; and (iv) suitable ranges of monthly magnitude calculated by IHA method were all in the scopes of those figured out by the traditional calculation method and Tennant method. All these findings can help to provide rational regulatory and managerial policy in relation to water resources to maintain the health of the various ecosystems in the Juma River, China.