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.

Full Text

   

Xiuquan Xu ¹, Jianen Gao ²

Affiliations
1 Institute of Soil and Water Conservation, CAS & MWR, University of Chinese Academy of Sciences, Yangling-712100, CN
2 Institute of Soil and Water Conservation, CAS & MWR, College of Natural Resources and Environment, College of Water Resources and Architectural Engineering, Institute of Soil and Water Conservation, Northwest A&F University, Yangling-712100, CN

Abstract

Multivariate statistical techniques, including cluster analysis (CA), principal component analysis (PCA), factor analysis (FA) and discriminant analysis (DA), were applied for the evaluation of temporal and seasonal variations and interpretation of a complex water quality data set at Yangling Section of Weihe River. Hierarchical cluster analysis grouped 12 months into three clusters, i.e., C1 (relatively highly polluted months), C2 (moderate polluted months) and C3 (less polluted months), based on the similarity of water quality characteristics. Factor analysis/principal component analysis, tested to the data sets of the three groups obtained from cluster analysis, identified 9, 6 and 7 latent factors explaining more than 76, 69 and 62% of the total variance in the data sets of C1, C2 and C3, respectively. The varifactors obtained indicate that parameters responsible for variation are mainly related to temperature and DO (natural), COD_Mn, turbidity, NH₄⁺, TN, pH and TOC (point source: domestic wastewater) in C1; temperature, DO and EC (natural), COD_Mn, TN, pH, and TOC in C2; and temperature, DO and EC (natural), COD_Mn, pH and TOC (point source: domestic wastewater and industrial effluents), turbidity and TN (non-point source: agriculture and soil erosion) in C3. However, discriminant analysis showed no significant data reduction, as it used 8 parameters (turbidity, EC, NH₄⁺, DO, TN, pH, temperature and TOC) affording more than 81% correct assignations in temporal analysis, while 8 parameters (COD_Mn, turbidity, EC, DO, TN, pH, temperature, TOC) affording more than 88% correct assignations in seasonal analysis. Thus, this research illustrated the necessity and usefulness of multivariate statistical techniques for analysis and interpretation of large complex water quality data sets, identification of possible pollution sources/factors and information about variation in water quality for effective river water quality management.

Keywords

Water Quality Assessment, Multivariate Statistical Techniques, Weihe River.

Full Text

   

Yuanxing Zhang ¹, Jianen Gao ², Hui Shao ¹, Hongjie Wang ¹, Chunhong Zhao ¹, Hong Wang ¹, Xiuquan Xu ¹

Affiliations
1 Northwest A&F University, College of Resources and Environment, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, National Engineering Research Center for Water-Saving Irrigation at Yangling, Yangling, CN
2 Northwest A&F University, Institute of Soil and Water Conservation, CAS & MWR, College of Water Resources and Agricultural Engineering, Yangling-712100, CN

Abstract

The terraced field widely distributed in Loess Plateau where serious soil and water loss happens, has a significant influence on watershed hydrological environment. At present, for the deficiency of watershed scale terraced fields hydrological environment impact assessment model and lacking of measured data, the terraced fields environmental impact assessment has attracted many attentions of the researchers. This paper adopts the hydrologic analogy combined with a scale physical model method, to infer the runoff and sediments in data-scarce area. Using the embedded terraced module SWAT model to assessment of terraced fields environmental impact, the results show that was a new way to conjecture the hydrologic data in data-scarce area. And the terraced field module can meet the accuracy requirement, the NS sufficient were both above 0.5 in calibration and verifying period. The soil erosion modulus of terraced fields contained in and removed from the watershed, was respectively 5.3% and 16.2% greater than the real. This indicates that the embedded terraced module SWAT model could be used in terraced fields environmental impact assessment in Loess Plateau small watershed.

Keywords

Terraced Fields, SWAT Model, Loess Plateau, Soil Erosion, Run-Off.

Full Text