Estimating water fluxes in the critical zone using water stable isotope approaches in the Groundnut and Ferlo basins of Senegal     

Djim M. L. Diongue  Christine Stumpp  Olivier Roupsard  Didier Orange  Frederic C. Do  Serigne Faye 《水文研究》2023,37(1):e14787

Sustainable water management in semi-arid agriculture practices requires quantitative knowledge of water fluxes within the soil-vegetation-atmosphere system. Therefore, we used stable-isotope approaches to evaluate evaporation (E_a), transpiration (T_a), and groundwater recharge (R) at sites in Senegal's Groundnut basin and Ferlo Valley pasture region during the pre-monsoon, monsoon, and post-monsoon seasons of 2021. The approaches were based upon (i) the isothermal evaporation model (for quantifying E_a); (ii) water and isotope mass balances (to partition E_a and T_a for groundnut and pasture); and (iii) the piston displacement method (for estimating R). E_a losses derived from the isothermal evaporation model corresponded primarily to Stage II evaporation, and ranged from 0.02 to 0.09 mm d⁻¹ in the Groundnut basin, versus 0.02–0.11 mm d⁻¹ in Ferlo. At the groundnut site, E_a rates ranged from 0.01 to 0.69 mm d⁻¹; T_a was in the range 0.55–2.29 mm d⁻¹; and the T_a/ET_a ratio was 74%–90%. At the pasture site, the ranges were 0.02–0.39 mm d⁻¹ for E_a; 0.9–1.69 mm d⁻¹ for T_a; and 62–90% for T_a/ET_a. The ET_a value derived for the groundnut site via the isotope approach was similar to those from eddy covariance measurements, and also to the results from the previous validated HYDRUS-1D model. However, the HYDRUS-1D model gave a lower T_a/ET_a ratio (23.2%). The computed groundwater recharge for the groundnut site amounted to less than 2% of the local annual precipitation. Recommendations are made regarding protocols for preventing changes to isotopic compositions of water in samples that are collected in remote arid regions, but must be analysed days later. The article ends with suggestions for studies to follow up on evidence that local aquifers are being recharged via preferential pathways.  相似文献   

Analysis of growing season carbon and water fluxes of a subalpine wetland in the Canadian Rocky Mountains: Implications of shade on ecosystem water use efficiency     

Dylan M. Hrach  Richard M. Petrone  Adam Green  Myroslava Khomik 《水文研究》2022,36(1):e14425

Mountain regions are an important regulator in the global water cycle through their disproportionate water contribution. Often referred to as the “Water Towers of the World”, mountains contribute 40%–60% of the world's annual surface flow. Shade is a common feature in mountains, where complex terrain cycles land surfaces in and out of shadows over daily and seasonal scales, which can impact water use. This study investigated the turbulent water and carbon dioxide (CO₂) fluxes during the snow-free period in a subalpine wetland in the Canadian Rocky Mountains, from 7 June to 10 September 2018. Shading had a significant and substantial effect on water and CO₂ fluxes at our site. When considering data from the entire study period, each hourly increase of shade per day reduced evapotranspiration (ET) and gross primary production (GPP) by 0.42 mm and 0.77 g C m^?2, equivalent to 17% and 15% per day, respectively. However, the variability in shading changed throughout the study, it was stable to start and increased towards the end. Only during the peak growing season, the site experienced days with both stable and increasing shade. During this time, we found that shade, caused by the local complex terrain, reduced ET and potentially increased GPP, likely due to enhanced diffuse radiation. The overall result was greater water use efficiency during periods of increased shading in the peak growing season. These findings suggest that shaded subalpine wetlands can store large volumes of water for late season runoff and are productive through short growing seasons.  相似文献   

黔北上奥陶统宝塔组头足类的聚爆深度分析及其地质学意义          下载免费PDF全文

彭庭祖  杨宇宁  王冬梅  池祥日 《地质论评》2023,69(1):33-48

上奥陶统宝塔组是扬子板块分布广泛的标志性地层单元,因富含类型多样的头足类化石及发育特殊的网纹状构造而闻名。目前,有关宝塔组沉积时期水体深度的分析都是基于沉积学和古生物学特征的定性推测,而且争议较大。笔者等在黔北尧龙山地区宝塔组采集到大量原域埋藏的头足类化石,根据它们的隔壁强度系数(Septal Strength Index,SSI)与聚爆深度的耦合关系,首次对这些头足类生活时的古海水深度进行定量化分析。通过选取符合SSI分析条件的16块Sinoceras和12块Michelinoceras标本,系统分析了SSI分别与外部特征和内部构造的相关性。结果显示,SSI随壳体长度及隔壁间距的增大而增加,随顶角角度的增加而减小,但与内部构造单一参数的相关性不大,可能受到多个内部构造参数的共同制约。定量化分析结果显示,尧龙山地区宝塔组中共埋出现的Sinoceras和Michelinoceras的SSI分别为5.564～10.829和11.432～19.532,对应的生态深度大约分别为128～169 m和228～280 m,表明两属头足动物生活时可能已经出现明显的生态分层现象,古生物地理区系也出现一定...  相似文献   

中国区域性骤发干旱特征分析          下载免费PDF全文

叶天  余锦华  叶梦茜  谢洁宏 《气象科学》2021,41(3):295-303

基于国家气象信息中心2 400多个观测站的候平均日最高气温、GLDAS 2.0/2.1的土壤湿度、蒸散发资料和ERA5的500 hPa位势高度、925 hPa风场再分析资料,定义了格点骤发干旱指数,在分析1979—2017年4—9月中国区域骤发干旱气候特征和骤发干旱指数的经验正交展开空间模态的基础上,确定骤发干旱发生频繁及变率大的区域,给出了区域性骤发干旱事件的识别标准,并对其演变过程进行合成分析,最后分析了典型个例的要素和环流特征。结果表明:骤发干旱多发于我国南方夏季,其中7月最多,以湖南和浙江地区发生最为频繁,这两个区域也是骤发干旱发生气候变率最大的区域。合成分析显示,高温是两个区域骤发干旱爆发的主要驱动因素:干旱爆发前一候,气温迅速升高,蒸散发快速增大,土壤湿度下降明显。2013年6—7月在湖南区域爆发了两次骤发干旱事件。第一次干旱爆发前,湖南地区500 hPa位势高度迅速增大,异常下沉气流导致降水减少和绝热增温,蒸散发随气温升高而增加,使土壤湿度减少,这次干旱由高温驱动;第二次干旱爆发前期,明显偏西、偏北且稳定的西北太平洋副热带高压使地表太阳净辐射通量增强、近地层的偏南气流使高温维持,蒸散发随降水而变化,这次干旱为降水减少所驱动,高温起促进作用。  相似文献   

微滴式农田蒸散器的研制          下载免费PDF全文

谢传宁  陈文军  简慰民 《大气科学学报》1993,16(2):238-244

首先介绍微滴式旱田和水田蒸散器的结构和原理,并与原旱田蒸散器进行了比较,讨论了仪器的性能。  相似文献   

产学研合作及其对海洋科技成果转化的启示     

彭伟 《海洋技术学报》2009,28(1)

产学研合作是促进海洋科技成果转化的重要措施.开展产学研合作应积极发挥产学研合作各方的优势.选择适当的合作模式.实现有效的产学研合作关键在于解决产学研合作的动力机制问题.以确保各方利益共享、风险共担.同时实现整体收益最大化的目标.  相似文献