Two Centuries-Long Streamflow Reconstruction Inferred from Tree Rings for the Middle Reaches of the Weihe River in Central China

Abstract

Water source is one of the most important concerns for regional society and economy development, especially in the Weihe River basin which is located in the marginal zone of the Asian summer monsoon. Due to the weakness of short instrumental records, the variations of streamflow during the long-term natural background are difficult to access. Herein, the average June–July streamflow variability in the middle reaches of the Weihe River was identified based on tree-ring width indices of Chines pine (Pinus tabulaeformis Carr.) from the northern slope of the Qinling Mountains in central China. Our model could explain the variance of 39.3% in the observed streamflow period from 1940 to 1970 AD. There were 30 extremely low years and 26 high years which occurred in our reconstruction for the effective span of 1820 to 2005. Several common dryness and wetness periods appeared in this reconstructed streamflow, and other tree-ring precipitation series suggested the coherence of hydroclimate fluctuation over the Weihe River basin. Some significant peaks in cycles implied the linkages of natural forcing on the average June–July streamflow of the Weihe River, such as the Pacific Decadal Oscillation (PDO) and El Niño-Southern Oscillation (ENSO) activities. Spatial correlation results between streamflow and sea surface temperature in the northern Pacific Ocean, as well as extremely low/high years responding to the El Niño/La Nina events, supported the teleconnections. The current 186-year streamflow reconstruction placed regional twentieth-century drought and moisture events in a long-term perspective in the Weihe River basin, and provided useful information for regional water resource safety and forest management, particularly under climate warming conditions.

Response Characteristics of Chinese Pine (Pinus tabulaeformis Carr.) Radial Growth to Climate and Drought Variability Reconstruction in Western Liaoning, Northeast China

“…The significant positive correlation of the SH chronology with May precipitation and the negative correlation with May mean temperature were consistent with the response pattern found for Yiwulv Mountain (YWL) (Figure 1) [11] and Ortindag sandy land [12] to the west of our study area, as well as the positive effects of precipitation and relative humidity in the previous growth season on pine radial growth in the current year [13][14][15][16][17][18].…”

“…Twelve El Niño events occurring in the reconstructed drought index series accounted for 38.71% of the extreme dry years, while nine La Niña events accounted for 31.03% of the extreme wet years. Similar cycles related to ENSO have been revealed in other tree-ring climate variable reconstruction series in surrounding regions [11,15,16,34,51,52].…”

“…Although the response degrees of the SH and WFY tree-ring index to climatic variables were different, both chronologies were positively correlated with monthly precipitation and relative humidity and negatively correlated with monthly mean temperature, indicating that the radial growth of Chinese pine in the study area was mainly affected by moisture conditions. Similar growth and climate relationships were found for Yiwulv Mountain [11], Ortindag sandy land [12] and the Loess Plateau, China [13][14][15][16][17]. Among them, the study conducted on Yiwulv Mountain (YWL), the nearest sampling site to our study area (Figure 1), showed that Chinese pine width was significantly positively correlated with precipitation in May, July and September and negatively correlated with temperature in May, June and July [13].…”

“…Significant positive correlations with SST in the central-north Pacific Ocean and negative correlations with SST along the west coast of North America suggested the effects of the Pacific Decadal Oscillation (PDO) on our study area (Figure 5b). Similar patterns of climate-related radial growth response have been found in tree-ring-based hydroclimatic reconstructions in the Hulunbuir sand land, Northeast China and the Weihe River basin, eastern Northwest China [15,41]. The adverse relationship between the Palmer drought severity index (PDSI) in northern China and the PDO index [38] support the drought variations in western Liaoning and surrounding areas modulated by the northern Pacific Ocean.…”

Estimation of Annual Maximum and Minimum Flow Trends in a Data-Scarce Basin. Case Study of the Allipén River Watershed, Chile

“…Time series reconstruction using a dendroclimatological approach [36][37][38][39][40][41] has been one of the most used methods to conduct hydrological long-term trends analyses. Tree-ring records provide continuous series of past environmental changes for the last several centuries and in some cases, millennia [36].…”