Nature Environment and Pollution Technology

Hongjie Wang ¹, Jianen Gao ¹, Jianmei Ji ¹, Xiuquan Xu ², Chunhong Zhao ³

Affiliations
1 College of Water Resources and Architectural Engineering, Northwest A & F University, Yangling, Shaanxi Province, CN
2 Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi Province, CN
3 College of Natural Resources and Environment, Northwest A & F University, Yangling, Shaanxi Province, CN

Abstract

Ecological base flow is a basic requirement of water flow for a healthy river ecosystem. But in Weihe River the ecological flow is not guaranteed because of the water shortage, high sediment concentration and considerable agricultural water use along the river. In this study, Baojixia under-tableland irrigation area was selected as a representative area to which a mathematical model of one-dimensional steady water non-uniform sediment regulation was applied, to analyse the impact of channel desilting on guaranteeing the ecological base flow of Weihe River. The results indicated that scouring and silting of the channel was significantly correlated with the channel water capacity and sediment content in water flows. In addition, channel desilting contributed to 55.9×10⁴m³ and 79.2×10⁴m³ water saving in the irrigation area in January and December which belonged to the dry season. Their contribution rates to basic flow were 3.5% and 4.9%, respectively.

Keywords

Ecological Base Flow, Sediment Dispatching, Sediment-Laden River, Weihe River.

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Jianmei Ji ¹, Huanjie Cai ¹, Jianqiang He ¹, Jian Wang ¹

Affiliations
1 College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling, Shaanxi, 712100, CN

Abstract

Wheat (Triticum durum) yields have increased significantly because of the increasing higher irrigation and fertilizer inputs since the last half of 20th century. With varying climate and rising population, increasing focus is being given to enhancing resource use efficiency while increasing yields. This study utilized the CERES (Crop Estimation through Resource and Environment Synthesis) - Wheat model to analyse the impact of irrigation, nitrogen (N) and climate on wheat yield, using 58-year climate data. Analyses were conducted using four assumed scenarios with step-by-step method. Results showed that the optimum irrigation and nitrogen ranges were not uncertain when taking into account a single factor. When considering both irrigation and nitrogen, the impact of irrigation on simulated grain yield was greater than that of nitrogen, which was similar to the results obtained from the experiments. The average variation in grain yield was attributed to irrigation (46.8%), nitrogen (5.5%) and climate (2.4%). Besides, relative humidity and maximum temperature were consistently and significantly correlated with grain yield under all conditions, while precipitation had a significant correlation with grain yield when no irrigation or N was applied, or one of them was applied. However, solar radiation was significantly correlated with grain yield when both irrigation and N were available.

Keywords

Water Use Efficiency, Climatic Factors, Marginal Production, Ceres-Wheat Model.

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