甘肃黄土高原气象旱度模式研究

Research on meteorological drought severity model for Loess Plateau in Gansu

干旱是限制甘肃黄土高原农业可持续发展最主要的自然灾害之一,研究适合该区的干旱指标,是进行有效干旱监测的基础。为了制定出考虑因素较全面、具有时空可比性的适合甘肃黄土高原情况的干旱指标,依据帕默尔旱度模式的基本原理和方法,针对甘肃黄土高原的实际情况,从建模资料长度、站点密度、可能蒸散计算、土壤田间持水量和径流计算等几个方面对原有模式进行了修正,用甘肃黄土高原12个代表站的资料,建立了旱度模式,并确定了权重因子。在此基础上,计算了20个代表站点的气象旱度值,并与实际旱情记载进行了对照检验。结果表明,用该模式计算的旱度值与实际灾情吻合得较好,能够反映出该区干旱程度的变化情况,特别是对一些重大旱段。通过修正后的甘肃黄土高原的气象旱度模式与原美国帕默尔旱度模式和中国1985年修正的帕默尔旱度模式的比较,进一步说明该模式适合应用于干旱评估和监测业务。

Drought is one of the most important natural disasters that restricts the sustainable development of agriculture in Gansu Loess Plateau. A drought severity index is the foundation of monitoring drought disaster.. In order to develop a meteorological drought severity index that considers meteorological factors more comprehensivly and is comparable in space and time , a further modified meteorological drought severity model for Gansu Loess Plateau was developed on the basis of fundamentals and method of the Palmer Drought Severity Model. Stations, calculation of potential evapotranspiration and runoff, etc. were revised in this model. The monthly meteorological index was computed at 20 representative stations from 1961 to 2000 by using the modified meteorological drought severity model for Gansu Loess Plateau, and the computed drought index was compared with the recorded drought situation. The result shows that the computed drought seveirty value is coincident with the practical drought situation, and can refleet the drought severity well , especially for those severe drought periods. The comparison was also made with the American PDSI and the China PDSI modified in 1985, which further indicates the reliability of this model.