Innovative Trend Analysis of Precipitation in the Lake Issyk-Kul Basin, Kyrgyzstan

Abstract

The analysis of various characteristics and trends of precipitation is an essential task to improve the utilization of water resources. Lake Issyk-Kul basin is an upper alpine catchment, which is more susceptible to the effects of climate variability, and identifying rainfall variations has vital importance for water resource planning and management in the lake basin. The well-known approaches linear regression, Şen’s slope, Spearman’s rho, and Mann-Kendall trend tests are applied frequently to try to identify trend variations, especially in rainfall, in most literature around the world. Recently, a newly developed method of Şen-innovative trend analysis (ITA) provides some advantages of visual-graphical illustrations and the identification of trends, which is one of the main focuses in this article. This study obtained the monthly precipitation data (between 1951 and 2012) from three meteorological stations (Balykchy, Cholpon-Ata, and Kyzyl-Suu) surrounding the Lake Issyk-Kul, and investigated the trends of precipitation variability by applying the ITA method. For comparison purposes, the traditional Mann–Kendall trend test also used the same time series. The main results of this study include the following. (1) According to the Mann-Kendall trend test, the precipitation of all months at the Balykchy station showed a positive trend (except in January (Zc = −0.784) and July (Zc = 0.079)). At the Cholpon-Ata and Kyzyl-Suu stations, monthly precipitation (with the same month of multiple years averaged) indicated a decreasing trend in January, June, August, and November. At the monthly scale, significant increasing trends (Zc > Z0.10 = 1.645) were detected in February and October for three stations. (2) The ITA method indicated that the rising trends were seen in 16 out of 36 months at the three stations, while six months showed decreasing patterns for “high” monthly precipitation. According to the “low” monthly precipitations, 14 months had an increasing trend, and four months showed a decreasing trend. Through the application of the ITA method (January, March, and August at Balykchy; December at Cholpon-Ata; and July and December at Kyzyl-Suu), there were some significant increasing trends, but the Mann-Kendall test found no significant trends. The significant trend occupies 19.4% in the Mann-Kendall test and 36.1% in the ITA method, which indicates that the ITA method displays more positive significant trends than Mann–Kendall Zc. (3) Compared with the classical Mann-Kendall trend results, the ITA method has some advantages. This approach allows more detailed interpretations about trend detection, which has benefits for identifying hidden variation trends of precipitation and the graphical illustration of the trend variability of extreme events, such as “high” and “low” values of monthly precipitation. In contrast, these cannot be discovered by applying traditional methods.

Trend Analysis of Annual and Seasonal River Runoff by Using Innovative Trend Analysis with Significant Test

“…As reported by Alifujiang, Abuduwaili [74], the ITA method's application at three sites in the Issyk-Kul Basin revealed that the precipitation exhibited significant increasing trends in summer and winter. Moreover, utilization of the MK trend test and ITA method demonstrated that the percentage of time series with significant positive trends of monthly precipitation was decreased from north to south by Alifujiang.et.al [74]. This study revealed that in the summer and winter seasons, the data series of most hydrological stations fell above the 1:1 (45 • ) line.…”

“…River discharge is determined by rainfall, which falls in the catchment area, and by evaporation, which depends on air temperature [72,73]. As reported by Alifujiang, Abuduwaili [74], the ITA method's application at three sites in the Issyk-Kul Basin revealed that the precipitation exhibited significant increasing trends in summer and winter. Moreover, utilization of the MK trend test and ITA method demonstrated that the percentage of time series with significant positive trends of monthly precipitation was decreased from north to south by Alifujiang.et.al [74].…”

Detection of Groundwater Levels Trends Using Innovative Trend Analysis Method in Temperate Climatic Conditions

“…The comparative analysis of data series can be carried out without statistical assumptions [19] and the resulting graphs facilitate the statistical interpretation [38]. The method has been intensively used in the past decade to identify trends on extreme seasonal and annual value sets for climatic and hydrological parameters [39,40]. The ease of tracking trends by comparative analysis of data strings has led to the application of this method to identify solar radiation trends [41] and can be included in the analysis of trends of groundwater levels connected with different extreme hydroclimatic phenomena [42] or climatic changes [43].…”

Trend Analysis and Comparison of Forecast Models for Production of Turkish Crayfish (Pontastacus leptodactylus Eschscholtz, 1823) in Turkey

“…Otherwise, the alternative hypothesis is the existence of a statistically significant decreasing/increasing trend in the given time series. Şen's innovative trend analysis methodology was commonly implemented to hydroclimatological time series observed at different locations through the world (Şen, 2014 and2015;Kişi et al, 2015;Ay et al, 2018;Gedefaw et al, 2018;Alifujiang et al, 2020).…”