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Temporal and spatial changes of agricultural water requirements in the Lancang river basin

Journal of Geographical Sciences 2012年第3期22卷 441-450页

作者： Gu Shixiang He daming Cui Yuanlai Li Yuanhua State key Laboratory of Water resources and Hydropower Engineering Science Wuhan University Yunnan Institute for Investigation Design and Research of Water Resources&Hydropower Engineering Asian International rivers Center Yunnan University department of Irrigation Drainage and Rural Water SupplyMWR

based on the data of eight meteorological stations from the 1950s to 2007, current cropping patterns, field water moisture management, we use the Mann-Kendall and the rescaled range Analysis methods to research the changes of humidity and crop irrigation water requirements in the Lancang river basin. the results show that the annual and dry season average temperatures significantly increased, and the dry season rainfall increased while wet season rainfall decreased. Evaportranspiration （ETo） increased during both dry and wet seasons at all stations except dali, Jianchuan and Gengma, and the aridity-humidity index decreased at most of the stations. the turning points of weather factors, ETo, the aridity-humidity index, paddy irrigation requirements and total agricultural water requirements occurred from the 1960s to the 1990s. the spatial changing tendency of paddy irrigation quota increased with the increase of altitude and latitude, and the correlation coefficients are 0.513 and 0.610, respectively. the maximum value is observed in Weixi, while the minimum in Mengla.

关键词： agricultural irrigation quota Lancang river the Longitudinal range-Gorge region

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Contribution of drought to Potential Crop Yield reduction in a Wheat-Maize rotation region in the North china Plain

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Journal of Integrative Agriculture 2014年第7期13卷 1509-1519页

作者： HU Ya-nan LIU Ying-jie TANG Hua-jun XU Yin-long PAN Jie Institute of Environment and Sustainable development in Agriculture Chinese Academy of Agricultural Sciences key Laboratory of Agri-Informatics Ministry of Agriculture/Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences Public Meteorological Service Center Chinese Meteorological Administration

With consecutive occurrences of drought disasters in china in recent years, it is important to estimate their potential impacts on regional crop production. In this study, we detect the impacts of drought on wheat and maize yield and their changes at a 0.5＆#176;＆#215;0.5＆#176; grid scale in the wheat-maize rotation planting area in the North china Plain under the A1b climate change scenario using the decision Support System for Agrotechnology Transfer （dSSAT） model and the outputs of the regional climate modeling system-Providing regional Climates for Impacts Studies （PrECIS）. Self-calibrating palmer drought severity index was used as drought recognition indicator. Two time slices used for the study were the baseline （1961-1990） and 40 years of 2011-2050. the results indicate that the potential planting region for double crop system of wheat-maize would expend northward. the statistic conclusions of crop simulations varied considerably between wheat and maize. In disaster-affected seasons, wheat yield would increase in the future compared with baseline yields, whereas in opposite for maize yield. Potential crop yield reductions caused by drought would be lower for wheat and higher for maize, with a similar trend found for the ratio of potential crop yield reductions for both crops. It appears that the negative impact of drought on maize was larger than that on wheat under climate change A1b scenario.

关键词： drought yield dSSAT A1b scenario climate change

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Pollution assessment of heavy metals along the Mekong river and dam effects

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Journal of Geographical Sciences 2012年第5期22卷 874-884页

作者： FU Kaidao SU bin HE daming LU Xixi SONG Jingyi HUANG Jiangcheng Asian International rivers Center Yunnan University Kunming 650091 China Yunnan key Laboratory for International rivers and Transboundary Ecology Security Kunming 650091 China department of Geography National University of Singapore 119260 Singapore

the resource development and changes of hydrological regime, sediment and water quality in the Mekong river basin have attracted great attentions. this research aimed to enhance the study on transboundary pollution of heavy metals in this international river. In this study, eight sampling sites were selected to collect the bed sand samples along the mainstream of the Mekong river. In addition, the contents of 5 heavy metal elements and their spatial variability along the mainstream of the river were analyzed. the geoaccumulation index （l^eo） and potential ecological risk analysis were employed to assess heavy metal pol- lution status in the mainstream of the Mekong river. the results show that the average con- tent of the heavy metal elements Zn is 91.43 mg/kg, Pb is 41.85 mg/kg, and As is 21.84 mg/kg in the bed sands of the Upper Mekong river, which are higher than those （Zn 68.17 mg/kg, Pb 28.22 mg/kg, As 14.97 mg/kg） in the Lower Mekong. the average content of Cr in the Lower Mekong is 418.86 mg/kg, higher than that in the Upper Mekong （42.19 mg/kg）. Luang Prabang has a very high Cr concentration with 762.93 mg/kg and Pakse with 422.90 mg/kg. the concentration of Cu in all of the 8 sampling sites is similar, except for in Jiajiu with 11.70 mg/kg and Jiebei with 7.00 mg/kg. the results of the geoaccumulation index reveal that contaminations caused by Zn and Pb while Pb and As are more than those by Zn in Upper Mekong. Cr is the primary pollutant in the Lower Mekong, especially at Luang Prabang and Pakse. Slight pollution with As also occurs in Pakse. the potential ecological risk index indi- cates that the potential ecological risk of heavy metals in the mainstream of the Mekong river is low. We argue that the pollution of water quality and contamination of heavy metals in bed sediment caused by mining of mineral resources or geochemical background values in the Mekong is not transmitted from the Upper to the Lower Mekong because of the reservoir sedimentation and

关键词： Mekong river basin heavy metal pollution geoaccumulation index potential ecological risk index

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