CAJ | 학술논문

引黄水量的削减将进一步加剧宁夏银北灌区农业用水短缺问题，合理应用地下水进行灌溉对保障作物产量具有重要意义。为探究地下水灌溉条件下土壤水盐与作物生长的互馈机制，该研究修正了HYDRUS-1D的土壤蒸发模块，并嵌入可模拟作物生长与产量的 EPIC 模块，以此提高该模型在农田水文过程模拟中的适用性。采用2008年银北灌区不同水质灌水处理的玉米田间试验数据对模型进行了率定与验证。进一步应用该模型探寻地下水灌溉条件下，土壤水盐动态及玉米产量对地下水埋深变动及灌溉的响应规律。结果表明，玉米产量随地下水埋深增大呈现先增后减趋势，为保障玉米产量应将地下水适宜埋深控制在140～155 cm，且灌水量不宜低于现状灌水量，即玉米生育期内灌3水，每次900 m3/hm2。该研究对干旱银北灌区农业生产具有重要意义。
인황수량적삭감장진일보가극저하은북관구농업용수단결문제，합리응용지하수진행관개대보장작물산량구유중요의의。위탐구지하수관개조건하토양수염여작물생장적호궤궤제，해연구수정료HYDRUS-1D적토양증발모괴，병감입가모의작물생장여산량적 EPIC 모괴，이차제고해모형재농전수문과정모의중적괄용성。채용2008년은북관구불동수질관수처리적옥미전간시험수거대모형진행료솔정여험증。진일보응용해모형탐심지하수관개조건하，토양수염동태급옥미산량대지하수매심변동급관개적향응규률。결과표명，옥미산량수지하수매심증대정현선증후감추세，위보장옥미산량응장지하수괄의매심공제재140～155 cm，차관수량불의저우현상관수량，즉옥미생육기내관3수，매차900 m3/hm2。해연구대간한은북관구농업생산구유중요의의。
Reduction of water diversion from the Yellow River will intensify water shortage problems in the Yinbei Irrigation District (YID). Reasonable use of groundwater for irrigation is helpful to maintain the agricultural production. Groundwater exploitation may cause groundwater level declines in local areas. This helps to reduce the salinity accumulation in the root zone but decreases the capillary rise. Thus, it is important to figure out the responses of soil water-salt dynamics and crop yields to groundwater table fluctuations for salinity control and stable yields. In this study, HYDRUS-1D model was modified by coupling with the EPIC (erosion-productivity impact calculator) crop growth module for simulating agro-hydrological processes. The new crop module could simulate crop height, leaf area index (LAI), above-ground biomass and crop yield. The information between HYDRUS-1D and EPIC was exchanged by daily step. Root water uptake under water and salt stress was calculated with HYDRUS-1D and imported to EPIC to limit crop growth. EPIC module estimated crop height, LAI and root depth for HYDRUS-1D to calculate soil water-solute dynamics. HYDRUS-1D assumed that soil evaporation remained at the potential rate unless pressure head of the soil surface decreased to a prescribed value. After then this prescribed value was set as a constant head to renew the top boundary condition. However, it cannot reasonably reflect the decrease stage of soil evaporation when using the constant head boundary. This may overestimate soil evaporation. Therefore, a new soil evaporation module, estimating soil evaporation reduction coefficient using soil water content of the top layer (0-10 cm), was added for better describing the soil evaporation under shallow water tables. With the experimental data collected from the maize field in 2008, the model was calibrated by the data of groundwater irrigation treatment and validated by the data of canal irrigation treatment. Simulated soil water content and solute concentration in the root zone (0-90 cm) showed good agreement with the measured values. Root mean square error (RMSE), mean relative error (MRE) and coefficient of determination for soil moisture were 0.03 cm3/cm3, 3.4% and 0.78, respectively. For solute concentration, RMSE, MRE, coefficient of determination were 1.6 g/L, 1.3% and 0.29, respectively. LAI and above-ground biomass values were fitted well with the observations. MRE values for estimated and measured LAI and above-ground biomass were 5.9% and 10.6%, andR2 were both larger than 0.95 for these two items. The model was then used to assess the impacts of groundwater table and irrigation changes on soil water-salt dynamics and maize yields. Nine groundwater depth (GWD) scenarios (100, 110, 125, 140, 155, 170, 185, 200 and 250 cm) and 6 irrigation treatments (0.6, 0.8, 1.0, 1.2, 1.4 and 1.6 times of the present irrigation) were considered. The results showed that soil water content and salt storage in the root zone declined with the reduction of groundwater level and irrigation amount. Due to the decrease of groundwater contribution and soil moisture, lowering groundwater depth resulted in a gradual increase of the average solute concentration in the root zone. Maize yields increased first and then decreased as the groundwater table declined. Generally, the maximum yields were achieved when GWD was between 140 and 155 cm. The maize yields may decrease with reducing the irrigation amount, therefore water-saving strategies were not recommended for local farmers with low incomes. Finally, the optimum groundwater depth of 140-155 cm was suggested, and three irrigations with an amount of 900 m3/hm2for each will be applied during maize growing period.