摘要:
龙子祠泉域是北方著名的岩溶大泉,目前泉流量衰减严重,评估泉域内涵养水源林工程对岩溶水增补效果成为一项重要研究课题.本文利用NOAA/AVHRR遥感数据,运用地表能量平衡系统(SEBS)模型并结合临汾气象站的实际观测数据(气温、气压、相对湿度和风速),反演了龙子祠泉域2014年4-10月的日均蒸散量和月均蒸散量,通过GIS的空间叠加对比分析了不同岩性和不同植被覆盖率条件下的陆面蒸散量特征.结果表明:碳酸盐岩地区陆面蒸散量与植被覆盖率之间呈正相关关系,而碎屑岩地区中等植被覆盖率的陆面蒸散量最低,在整体上碎屑岩地区的陆面蒸散量要高于碳酸盐岩地区.仅从陆面蒸散量的角度考虑,在碎屑岩地区保持中等的植被覆盖率将有利于增加岩溶水的入渗补给量,而在碳酸盐岩地区开展植树造林将提高陆面蒸散量,不利于降水入渗补给.
Abstract:
The Longzici spring system,one of the largest karst spring in North China,is located in the western margin of the Linfen basin,covering an area of 2,250 km2.The springs discharge at an annually average rate of 4.81 m3/s derived from the records from 1955 to 2013.The karst water has been an important source for local water supply.But now the spring flow dramatically degrades because of climate change and human activities.Precipitation is the main source of the spring water recharge.This recharge occurs in two ways,namely the infiltration of precipitation over the carbonate rock areas and linear leakage of stream and river water.So it is very important to evaluate the recharge of karst water through an afforestation project.Based on NOAA/AVHRR data,the daily and monthly evapotranspiration (ET) of the Longzici spring are estimated during the period of 2014.4-2014.10,using surface energy balance system (SEBS) and the data of meteorological stations in Linfen.The ET has a monthly average value of 99.21 mm,with the maximum monthly value of 197.26 mm in June and the minimum one of 40.49 mm in April.In addition,the regional ET over different lithology and vegetation coverage rates are analyzed through spatial overlay.The results indicate that the ET increases with the increasing vegetation coverage rates in the carbonate rock outcrop regions,while it is the lowest in the medium vegetation coverage rate of clastic rock regions.Overall,the ET in the clastic rock regions is higher than that in the carbonate rock outcrop regions.If only ET is taken into consideration,keeping the medium vegetation coverage rate in clastic rocks will be favorable to increasing of recharge of karst water and afforestation in carbonate rock areas will enhance ET but not favorable to recharge from rainfall infiltration.
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