为了评估气候变化对灌区农业供需水量的影响,基于系统动力学软件STELLA(structure thinking experimental learning laboratory with animation)建立了宝鸡峡灌区供需水量计算模型,结合灌区气象水文数据,利用非一致性水文频率计算原理,预估了未来可供水量和气候变化情景,模拟了气候变化情景下不同规划水平年灌区农业供需水状况。结果表明:灌区主要水源渭河径流在1989年发生跳跃变化,跃幅为-14.25亿m~3,各典型年预估径流量(1989-2030年)比原序列(1954-2010年)对应值减少40%~55%,导致农业可供水量锐减;在alpha=0.05的显著水平上,1981-2010年灌区降水下降不显著,平均气温、最高气温显著上升而相对湿度和风速显著下降,其他因子无明显趋势;灌区未来各典型年农业需水量2030年比2010年增加1.08~2.19亿m~3,水资源供需平衡指数上升9.06%~14.46%,说明灌区农业供需水平衡状况受气候变化影响显著,必须在规划、设计和管理中予以考虑并采取积极的应对措施。研究结果为气候变化条件下灌区农业水资源合理配置提供了参考。
英文摘要:
Climate change has significant influences on irrigation water demand (IWD) and available irrigation water supply (IWS), which poses grave challenges to farmers and administrators of agriculture and water resources. Due to the complexity and uncertainties from climate, agriculture and water systems, only a few studies have combined these systems together, especially at irrigation district scale. Furthermore, most climate change scenarios (CCS) are continuous time series with uncertainties, meanwhile the corresponding CCS of the typical hydrological years are deficient. Thus it is difficult for the administrators from water sectors and agriculture to make positive responses to climate change. The object of the study was to provide an approach to estimate and assess the influences of climate change on IWS and IWD systems in irrigation district. The study area was a typical northern irrigation district of China, the Baojixia Irrigation District. The model considering IWD, IWS and CCS was developed using system dynamics software i.e. structure thinking experimental learning laboratory with animation (STELLA). There were four function modules: IWDM, IWSM, CCSM and WSDBI. CCSM included the reference crop evapotranspiration (ET_0) and the climate factors of future typical hydrological years. Climate factors (i.e. precipitation, air temperature, wind speed, relative humidity and sunshine duration) were predicted using historical data and hydrological frequency calculation principle of inconsistent series. ET_0 was calculated by Penman-Monteith equation from the Food and Agriculture Organization of the United Nations (FAO) based on the predicted climate factors. IWDM calculated the irrigation water demands of main crops (wheat, maize, cotton, cole and apple). Crop water requirement was calculated by a simple soil water balance model including effective precipitation, crop coefficient (Kc) and ET_0. Net irrigation water demand (NIWD) was the sum of crop water requirements multiplied by their planting areas. IWD was NIWD divided by coefficient of irrigation water effective utilization. IWS was the available irrigation water supply which consisted of ground water and surface water (runoff of Weihe River and reservoirs). The runoff was estimated by historical data and hydrological frequency calculation principle of inconsistent series.