River ecosystem functions include regulating the weather, improving ecological environments, maintaining biodiversity, and providing services to society [1,2]. A healthy river should be the dialectical unity of natural attributes [3,4], such as the environment, as well as social attributes, such as ecosystem services [5,6]. A healthy river should be both a river with a healthy ecosystem and a river where people and water exist in harmony. River health status is an assessment tool for river management
River water is necessary for production, livelihood and ecological balance [1]. Changes in river runoff directly affect the development and utilization of water resources [2] and thereby societal and economic development [3]. Studying the evolution of runoff and its influencing factors can provide a scientific basis for the management, protection and sustainable use of water resources [4, 5]. The change in river runoff is an important manifestation of climatic influence, especially precipitation and human activities in basins [6]. Thus, river runoff is an active area in global change research [7,8]. The fifth assessment report of the United Nations Intergovernmental Panel on Climate Change (IPCC) predicts that in the 21 st century, global climate change will increase surface runoff in high-latitude regions and humid tropical regions and decrease surface runoff in most arid subtropical regions and Mediterranean regions [7]. However, the causes of runoff changes are complex. Although climate change [8, 9] (e.g., precipitation) is the main influence in river runoff changes, the potential increase in evapotranspiration is also considered to be
The stable operation of a variable frequency pump is of great importance to the management of a water supply project. Analyzing the operation performance based on monitoring data is necessary for maintaining the stable operation of a variable frequency pump. Several sensors are installed at six monitoring points on the pump to collect signals including vibration velocity, vibration acceleration and vibration displacement. Monitoring signals are preprocessed by smoothing, adjusting waveform trend and filtering on the basis of Fast Fourier Transform (FFT). Then, the vibration features are extracted by power spectrum analysis and cepstrum analysis methods. According to the extracted features, the vibration law and actual operation performance of a variable frequency pump under different operating conditions are analyzed. Results indicate that the vibration amplitude of the pump varies sharply under the operating conditions of [15 Hz, 20 Hz] and [30 Hz, 35 Hz]. The operating condition of [0 Hz, 15 Hz] is the restricted operating area of the pump. The vibration and noise continue increasing under the operating conditions of [35 Hz, 50 Hz] and reach the maximum values at 50 Hz. Therefore, the optimal operating is within the range of [20 Hz, 30 Hz]. Finally, by analyzing the critical values of the operating conditions, the fault diagnosis and the evaluation of the operating status are conducted.
Soil erosion is a serious threat to ecosystem sustainability and it is affected by rainfall characteristics (e.g., rainfall intensity, duration, temporal variation, and velocity) [1-3], underlying surface conditions (e.g., topography, slope gradient, and vegetative cover) [1, 4-8]. Soil erosion has been identified as one of the major processes contributing to soil and water quality degradation [9-11]. Rainfall intensity and slope gradient are the two dominant influences on hydrologic responses related to soil erosion. They have been studied via numerical simulation, experiments and analytical solutions (e.g., [1, 3, 12]). Rainfall intensity is a dominant factor in rainfall-runoff and soil erosion processes, with higher rainfall intensity generating a larger runoff peak [3]. He et al. (2012) investigated the influence of slope gradient on both runoff and sediment yield under
The hydrological characteristics of the Xiaoqing River Basin (above Chahe Hydrological Station) in Shandong Province, China are changing due to increased urbanization. It has been found that since 1985 the constructed land area in the river basin has increased by 119% in 2015. Any changes in the river basin may increase the flood frequencies which may have severe consequences downstream of the river. We simulated the influence of underlying surface changes on flooding in the Xiaoqing river basin. The hydrological model HEC-HMS, a rainfall- runoff simulation model, was used to simulate the flood volume and the peak discharge values under the two underlying surface conditions in 1985 and 2015. The results indicated that influence of increased urbanization in 2015 increased in the flood volume and the peak discharge by approximately 17.8% and 15.4% on average respectively. Also the runoff R increases by 0.0058 mm for each unit increase of CN
2S
value under the unit rainfall.
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