Song Xianfang

A study of interaction between surface water and groundwater using environmental isotope in Huaisha River basin

The surface water and groundwater are important components of water cycle, and the interaction between surface water and groundwater is the important part in water cycle research. As the effective tracers in water cycle research, environmental isotope and hydrochemistry can reveal the interrelationships between surface water and groundwater effectively. The study area is the Huaisha River basin, which is located in Huairou district, Beijing. The field surveying and sampling for spring, river and well water were finished in 2002 and 2003. The hydrogen and oxygen isotopes and water quality were measured at the laboratory. The spatial characteristics in isotope and evolution of water quality along river lines at the different area were analyzed. The altitude effect of oxygen isotope in springs was revealed, and then using this equation, theory foundation for deducing recharge source of spring was estimated. By applying the mass balance method, the annual mean groundwater recharge rate at the catchment was estimated. Based on the groundwater recharge analysis, combining the hydrogeological condition analysis, and comparing the rainfall-runoff coefficients from the 1960s to 1990s in the Huaisha River basin and those in the Chaobai River basin, part of the runoff in the Huaisha River basin is recharged outside of this basin, in other words, this basin is an un-enclosed basin. On the basis of synthetically analyses, combining the compositions of hydrogen and oxygen isotopes and hydrochemistry, geomorphology, geology, and watershed systems characteristics, the relative contributions between surface water and groundwater flow at the different areas at the catchments were evaluated, and the interaction between surface water and groundwater was revealed lastly.

Distributions of phosphorus fractions in the sediments of a river–lake system: a case study in Huai River catchment area, China

Phosphorus (P) forms, with respect to sediment characteristics, and an in-stream sluice were studied in the river-lake system, Huai River catchment area, China. The mean of total P in sediments in the mainstream of the Huai River was higher than that in the Hongze Lake. It was found that P fractions varied in the sediments throughout the river and lake. Detrital-P was the dominant P fraction in the mainstream and organic P and detrital-P were the dominant P fractions in the lake, which could indicate: biologically available and non-biologically available forms. Useful information for the interpretation of P fractions could also be obtained from major sediment characteristics. Whether the relations between P fractions and grain size characteristics were significant or weak, 0.125 mm was a threshold grain size for P fraction distribution in sediment. In addition, the Bengbu Sluice, one of the most important in-stream facilities in the Huai River catchment area, regulated not only the transport of P in sediments upstream and downstream of the sluice, but also the distribution of P fractions in the river-lake system. Therefore, it was confirmed that nutrient loadings could be prevented from reaching the watershed, as well as improved ecological diversity by integrating sluice operation.

Controlling Factors of the Stable Isotope Composition in the Precipitation of Islamabad, Pakistan

Significant temporal variations in δ18O and deuterium isotopes were found in the rainfall water of Islamabad, Pakistan, over a 15-year period (1992–2006). The data were obtained from the International Atomic Energy Agency/Global Network of Isotopes in Precipitation (IAEA/GNIP) database, and statistical correlations were investigated. In particular, this study provides the first detailed analysis of GNIP data for Islamabad. Both dry (1999-2000) and wet years (1994, 1997, and 2000) were chosen to investigate the correlations between precipitation amount, vapor flux, and temperature. We observed obvious differences between the dry and wet years and among seasons as well. Long-term features in the isotope composition agreed with the global meteorological water line, whereas short-term values followed rainfall amounts; that is, a total of 72% of the precipitation’s isotopic signature was dependent on the rainfall amount, and temperature controlled 73% of the isotopic features during October to May. The lower d-excess values were attributed to conditions during the spring season and a secondary evaporation boost during dry years; precipitation originating from the Mediterranean Sea showed high d-excess values. Overall, the results of this study contribute to the understanding of precipitation variations and their association with water vapor transport over Islamabad, Pakistan.

Effect of land use on soil properties in debris flow bottomland: a case study at Xiaojiang Basin, Yunnan

In order to understand the effect of different land use on soil physics and nutrients properties of the debris flow bottomland, a case study at Daqing gully (in Xiaojiang Basin, Yunnan) was conducted in 2004. Soil samples were taken at depth of 0-10, 10–20, 20–40, 40–60, 60–80 cm under three land use patterns crop bottomland(CL), forest bottomland(FL), and barren bottomland(BL). The results showed that the developing bottomland to CL promoted soil toaccumulate total phosphorus (TP) and available phosphorus (AP), pH value transfered from neutral to alkalescency, and organic matter decreased significantly. Furthermore, the contents of total nitrogen (TN) and available nitrogen (AN) in CL were lower than that of FL and BL because the growth of crops consumed more nutrients in soil. The results also showed that the contents of TP, AP and available potassium (AK) in soil were positively correlated with soil particle.