Evapotranspiration capture and stream depletion due to groundwater pumping under variable boreal climate conditions: Sudogda River Basin, Russia | Capture de l’évapotranspiration et diminution du débit des cours d’eau dus au pompage des eaux souterraines dans des conditions climatiques boréales variables: Bassin de la Rivière Sudogda, Russie Captura de la evapotranspiración y el agotamiento de una corriente debido al bombeo del agua subterránea en variables condiciones climáticas boreales: Cuenca del Río Sudogda, Rusia 在多变的北方气候条件下由于抽取地下水致使土壤水分蒸发蒸腾损失总量捕获及河流河水的消耗:俄罗斯Sudogda河流域 Captura de evapotranspiração e rebaixamento de riachos pelo bombeamento de águas subterrâneas sob condições climáticas boreais variáveis: Bacia do Rio Sudogda, Rússia Влияние эксплуатации подземных вод на эвапотранспирацию и речной сток при многолетней изменчивости гумидного климата на примере бассейна р. Судогда, Россия

Groundwater pumping and changes in climate-induced recharge lead to lower groundwater levels and significant changes in the water balance of a catchment. Water previously discharged as evapotranspiration can become a source of pumpage. Neglecting this effect leads to overestimated streamflow depletion. A small river basin (Sudogda River Basin, Russia) with a boreal climate and with long-term records of groundwater head and streamflow rate (showing that the measured stream depletion is less than the pumping rate) was investigated. The role of evapotranspiration in the water balance was analyzed by a hydrogeological model using MODFLOW-2005 with the STR package; the annual variation in recharge was obtained with the codes Surfbal and HYDRUS. The Sudogda River Basin was classified according to landscape and unsaturated-zone texture classes, and for each classified zone, the unsaturated-zone flow simulation was used to calculate the annual recharge dynamics for the observation period. Calibration of the regional flow model was conducted using flow and head observations jointly for two steady-state flow conditions—natural (before pumping started) and stressed (pumping). The simulations showed that pumped water originates from three sources: intercepted baseflow (75% of the annual total pumping rate), the capture of groundwater evapotranspiration discharge plus increased groundwater recharge (17%), and induced stream infiltration (8%). Additionally, multi-year precipitation records were analyzed to detect any long-term recharge and pumping water-budget changes. The results showed that increasing groundwater recharge by natural precipitation leads to (1) decreased intercepted baseflow and induced streamflow infiltration and (2) increased intercepted evapotranspiration discharge, thereby reducing stream depletion.