Acta Geographica Sinica ›› 2000, Vol. 55 ›› Issue (3): 257-265.doi: 10.11821/xb200003001
LIU Chang ming1,2, CHENG Li 1
Viewing the more and more serious phenomena of course drying up of lower Huanghe River, taking 1987 for example, the total duration of drying up reached 226 days. Based on the systematic analysis of the influencing factors, two aspects from both water demand and water supply should be considered. And in the aspect of water supply there exist four layers, that is, precipitation, transpiration, runoff, and groundwater, that affect the drying up of lower Huanghe River. Considering the drying up takes place at the dry season every year, base flow must play an important role. Furthermore, the monthly natural runoff from 18 hydrological stations along the main course of the Huanghe River between the 1950s and the 1990s were divided into four series which are analyzed separately with time series analysis. Theses four series are yearly runoff series, wet season runoff series (from July to Oct), dry season runoff series (from Sep to June next year), and the lowest monthly runoff series as base flow. In this way, the dynamic law about the runoff in the Huanghe River basin was brought to light comprehensively and systematically. Some very meaningful conclusions have been drawn. First, the runoff in lower reaches of the Huanghe River comes mainly from the upstream runoff rather than from local precipitation and transpiration. Second, the drying up is mostly caused by human exploitation. Viewing from these points, a uniform basin exploitation and management should be put into practice. The year of 1999 is the best example. In that year because a uniform basin management concerning water resource utilization started to carry out, the course drying up decreased to 42 days. Third, the base flow of the Huanghe River from the very start of the middle reaches has been keeping on dropping in the last 4 decades, which would lead to a more deep thought about reasons and strategic ideas for the lower Huanghe River drained dry and managerial policy. Because the bed at the lower reaches of the Huanghe River has been raised higher than the surrounding ground, it is impossible for groundwater at the lower reaches to flow into the courses. The decreasing base flow in the middle reaches in the past 40 years caused the decrease of base flow, which might partly lead to the drying up. Last, base flow is not directly related with yearly runoff of the Huanghe River, since they have different periods. Finally, orthogonalization & selection model could be applied satisfactorily into the forecasting of runoff in the Huanghe River. The finial predicting function is just as following. q[DD(-3/4]^(N+t)=φ 0+∑ki=1φ if′ i(N+t) t=1,2,… Here, q[DD(-3/4]^ is the predicting runoff; f′ is mean generation function; and φ 0 and φ i are coefficients. With the model, the similitude precision could be about 90%. For example, the calculated runoff at the monthly lowest in 1987 is only 12 03 hundred million m\+3 per year, which is so low that its anomaly percentage is 14 1%. The result accords with the real drought background, which made the course drying up worst in 1987. In one word, both human and natural factors exert impacts on the courses drying up of the lower Huanghe River to different degreed and from different ways.
time series analysis,
orthogonalization & selection model,
dried-up of Huanghe River
LIU Chang ming, CHENG Li . Analysis on Runoff Series with Special Reference to Drying up Courses of Lower Huanghe River[J].Acta Geographica Sinica, 2000, 55(3): 257-265.
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