| For the water balance relationship between precipitation, evaporation and soil water, the global climate change will certainly influence the future crop demand irrigation pattern. Under the future climate change pattern, the randomness, trend, periodicity and time rhythm of meteorological factors, such as precipitation, temperature and radiation, will change. The change of these meteorological factors will directly influence crop growth condition and then cause crop demand irrigation to change. Especially the time rhythm change of temperature will directly influence length of crop growth period and the starting and ending time and then cause the phenological period to change. Crop phenological period is one of the most sensitive factors to characterize the climate change’s influence on agriculture, as the hotspot and leading edge in this field. Studying the crop demand irrigation change based on pheological period under climate change, can provide direct technological support to agriculture water supply and demand study, and is vital to agriculture system regulation.Previous phenological period research based on phenology observation data, which restricted the regions lack of data, while this paper studiedthe crop growth period accumulated temperature threshold to make up the lack of Heihe River phenological period observation data. The lowest active accumulated temperatures for crop growth have been used to accumulate the starting and ending time of growth period for different crops, with all results in the actual measurement extents. The climate tendency rate is used to study phenology change rule in crop growth period: for wheat, the seeding stage bringing forward5-9days, emergence stage bringing forward7-8days, tillering stage bring forward5-6days, elongation stage bringing forward3-4days, heading stage bringing forward5-7days, soft dough stage bringing forward14d; for corn, the seeding stage bringing forward4days, emergence stage bringing forward2d, spinning stage bringing forward2days, soft dough stage bringing forward5days. The daily meteorological data in1961to2010was used to analyze the break point of temperature, which was then set to be climate change influence infection point. Combined with phenological period change rule, the spatial-temporal evolution of crop demand irrigation was studied based on crop phenological period. Also the water demands of whether considering crop phenological period’s influence or not were compared. It breaks through the limits of previous studies that only the relationship between agriculture climate factors and crop demand irrigation and the demand changes under rising temperature pattern were been considered. The results showed that under climate change, without considering phenological period, the wheat water demand irrigation increased6%, that of the corn increased0.7%. Considering crop phenology change, for wheat, the demand irrigation date was10days in advance, the demand days was shortened7days, the demand water reduced11.5%; for corn, the demand irrigation date was9days in advance, the demand days was shortened7days and the demand water reduced1.8%.Based on the existed study achievement, the paper chose temperature and phenological period change to be control factors to set8future climate change patterns, and the crop demand irrigation was studied under different climate change patterns. As the results, for wheat, when the temperature went up1℃, the starting time of growth period was2days in advance, the growth period was shortened2days and the demand water increased1.4mm. For corn, the starting time of growth period was3days in advance, the growth period was shortened4days and the demand water reduced0.9mm.Based on the analysis of Heihe River irrigation regime and the above study achievements, with the goal to develop society-economy and ecology sustainably, the countermeasure for the basin agriculture irrigation was put forward to reply the climate change influence. |
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