Baohong Lu

Risk Assessment of Regional Water Resources and Forewarning Model at Different Time Scales

AbstractWith the goal of making full use of water resources, a risk assessment of regional water resources and a forewarning model was studied in this paper. The model is built upon risk indexes in the system, proceeding from the whole structure and its component parts at different time scales. A long-term approach is taken to establish the long-term forewarning model of regional water resources with three levels of prediction, assessment, and forewarning. An hydrological model is employed to simulate the further value of an index. Set pair analysis method is adopted to calculate the connection degree of index risk and systematic risk through a multivariate connection number, while the weight of a single index is determined on the different influences and their respective connection degrees are updated. The comprehensive assessment is made by an assessment matrix with connection degree of comprehensive index. The comparison judging method is used to compartmentalize the warning degree of water resources o...

Optimization of habitat protection area based on analytic hierarchy process (AHP) at Chongqing Reach in Wujiang Basin

The construction of hydropower stations will destroy or be disadvantage to environments, especially the cascade hydropower stations. How to find a similar suitable environments for habitat is an important content during protecting the ecological integrity. With the purpose of protecting the biological integrity of Chongqing Reach in Wujiang Basin, the paper chooses Chongqing Reach in Wujiang Basin as a study area, applies the analytic hierarchy process (AHP) on the basis of analyzing the condition of the main stream and chief tributary of Chongqing Reach, and selects seven factors, such as the kinds and quantity of fish resources, the hydropower development intensity, the extent of reservoir inundation, the population of the basin, etc. Through calculating and analyzing, Changxi tributary in Chongqing Reach of Wujiang Basin is the best site to establish habitat protection area.

Wavelet analysis of δ 18 O time series of monthly precipitation

A method based on wavelet transform is introduced to analyze δ18O time series in precipitation. Multi-Resolution Analysis (MRA) and periodicity analysis were conducted with Dmey wavelet function on the monthly average values of δ18O in precipitation from1961 to 2005 observed by the Vienna station, which provided a data-based approximation on the evolution of monthly oxygen-18 composition in precipitation in the Vienna station. It was found that the δ18O dynamics in precipitation was relatively stable and had a decrease trend on the whole during 1961 ∼ 1982. Periodicity analysis showed that the enrichment- depletion periodicity of oxygen-18 composition at the scale of 14.5years (174months) and 7.5 years (88months) was 3 and 5 times, respectively. Periodically regular pattern of wavelet transform coefficient (Wƒ (α, b)) at the scale of 4.2 years was consistent with that at the scale of 7.5 years. The average fluctuation ranges of wavelet transform coefficients at the scale of 4.2 years and 7.5 years were bigger than that at the scale of 14.5years, which indicated that the time series of δ18O in precipitation at the Vienna station had prominent periods of 4∼7.5years.

Responses of Streamflow to Climate Change and Human Activities in a River Basin, Northeast China

It is now common knowledge that many water resources stresses relate to access to water within a basin. Yi River Basin, a typical river basin characterized by intensive agricultural processes, significant population growth, and water management, has been undergoing grave water problems. In this paper, the long-term trend of precipitation and streamflow in Yi River Basin, from 1964 to 2010, was investigated via Mann-Kendall test. The change point occurred in the year 1965 dividing the long-term series into two periods. Climate elasticity method and linear regression method were implemented to quantify the impact of precipitation and human activities on runoff and presented basically consistent results of the percentage change in an annual runoff for the postchange period. The results reveal that the decline of annual runoff in postchange period is mainly attributed to precipitation variability of 53.66–58.25% and human activities of 46.34–41.74%, as estimated by climate elasticity method and linear regression method, respectively. This study detected the changes in the precipitation-streamflow relationship and investigated the possible causes in the Yi River, which will be helpful for providing a reference for the management of regional water resources.

Study of the Temporal and Spatial Distribution of Water Temperature in Ertan Reservoir Based on Prototype Observation

When a reservoir is built, it will change the hydraulic features of the natural river, and cause thermal stratification which has significantly influence on the reservoir area and downstream ecological environment. Through analysis of the temporal and spatial variations of the observed temperature in terms of the prototype temperature observations in Ertan reservoir, the preliminary conclusions can be gained as follows: the water temperature distribution in Ertan reservoir is basically represented as isothermal in the same depth plane, and as stratifies along water depth. The great monthly variations of water-temperature in the reservoir are affected by the air temperature obviously.

Precipitation Trend Analysis by Mann-Kendall Test: A Case of Tianchang County Anhui Province, China

The purpose of this research is to study the temporal variability of precipitation time series of Tianchang County in Anhui Province, China to aid in the understanding of the state of the hydrology of the catchment. Trend analysis of one of the main component of the water balance of a catchment and a climate variable, precipitation was conducted with the aim of detecting a possible trend in the precipitation time series of Tianchang County, the non-parametric Mann-Kendall test was applied to precipitation series from 1951-2010 of Tianchang County. It was performed using Trend (version 1.0.2) to identify the significant positive or negative trends in the precipitation data if any. The 59 years period of precipitation data for the different towns in whole area showed, on the whole, some significant trend at an alpha level of 0.01 and 0.05 when grouped into the four seasons present in the area. The trend analysis revealed an overall upward and significant trend in five towns namely Datong, Xinjie, Shiliang, Qinlan and Tongcheng with downward statistically non-significant trend in the other ten areas .Using hypothesis testing, the null hypothesis states that there is no trend and alternative state there is a trend. From the results we reject the null hypothesis within the level of confidence 0.05 and 0.01. The rising rate of precipitation in some months and decreasing in others signifies an overall random pattern in the time series. This result is a part contribution to the effect of Climate change on hydrology and indicates that there is still room for research on the impact of climate change to ensure sustainable development in future.

Correlation Analysis in Study of Relationship between 18O and Water Quality Indexes

At the background of water diversion project from the Yangtze River to Taihu Lake, the experiment of diverting water from Taipu River was implemented from March 22 to April 7 in 2006. Synchronous isotope monitoring as well as water quantity and water quality is carried out. Combining water quality index and isotope abundance data, a grey correlation analysis has been made between six major water quality indexes and δ 18O values during sluice-supply water period, the pump-supply water period and the whole diverting period. Correlation degrees of the whole diverting water period are higher than that of the two different diverting water period for the reason that data of normal diverting water period which from April 5 to 7 is included in calculating correlation degrees during the whole diverting period. Meanwhile, all the correlation degrees except TP during the sluice-supply water period are higher than that during the pump-supply water period. It shows that pump-supply water had more obvious influence to the correlation degrees for the reason that there are more releasing water during pump-supply water period than sluice-supply water period. Furthermore, correlation degrees of the three branches upper Huangpu River are also calculated respectively. The results show that the correlation degrees of Xiaziwei and Sanjiaodu have the similar chang trend except the correlation degrees of NH3-N and TN because of the supply of Taipu River and the river network around to the north branch Xietang and the middle branch Yuanxiejing. At last, it comes to the conclusion that diverting water from Taipu River have great improvement to the water environment of upper Huangpu River. And 18O as well as water quantity have a significant correlation with water quality.