Ecological Flow Regime and its Satisfactory Degree Assessment Based on an Integrated Method

Abstract

Ecological flow regime (EFR) evaluation is essential in river ecosystem protection. To evaluate and maintain EFR under a changing environment reasonably, an integrated method based on both the monthly 7Q10 method and biological analysis method was put forward for its simple modelling and small data requirement, and then reasonable EFR was obtained after a reasonable check by the Tennant method. Meanwhile, the concept and quantitative formula of the ecological flow regime satisfactory degree (EFRSD) were recommended and successfully applied in the Luanhe River. The results showed that the flow regime of the Luanhe was significantly interrupted by human activities after 1979, and EFRSD has been distinctly damaged since 1998; after 1979, from good to bad, the EFRSD of the Luanhe was the upstream, midstream and downstream. Then the driving forces leading to the Luanhe's EFRSD deterioration that included reduction in the natural rainfall, construction and operating of water conservation projects, and overexploitation of groundwater were discussed and analyzed. Finally, countermeasures for the ecological rehabilitation of the river were pertinently put forward.

Evaluation of Wanggu Watershed Carrying Capacity on Water System Indicators in Southeast Sulawesi, Indonesia

“…The flow regime coefficient is the ratio between the maximum discharge (Q max ) and minimum discharge (Q min ) of a river in the watershed (Asdak, 2014). The flow regime coefficient is one of the most decisive parameters in monitoring and knowing the flow capacity of a river from time to time (Xu et al, 2019), especially the highest discharge during the rainy season and the lowest discharge during the dry season (Berhanu et al, 2015;Handayani et al, 2019). The results of the analysis of river regime coefficients in the Wanggu watershed are presented in Figures 2 and 3.…”

Dynamic Simulation of Ecological Flow Based on the Variable Interval Analysis Method

“…At present, the ecological flow calculation includes four methods, as shown in Table 1: hydrological methods, hydraulic methods, habitat simulation methods, and holistic methods [15]. Among them, hydrological methods are based on a long series of historical run-off data, and take a fixed flow percentage as the required flow process of the river; these are generally used for reference or method comparison, including the Tennant method [16][17][18], Texas method [19,20], flow duration curve (FDC) method [21,22], range of variability approach (RVA) [23][24][25], minimum average 7 day (consecutive) flow expected to occur once every 10 years (7Q10) method [26,27], annual distribution method [28,29], monthly frequency calculation method [30,31], monthly guarantee rate method [32,33], minimum monthly average flow method [34,35], and the Northern Great Plains Resources Program (NGPRP) method [36,37]. The hydrological methods are simple and convenient, and do not require on-site monitoring, but the accuracy is low, due to single factor.…”