Decrease of river runoff in the Lake Balkhash basin in Central Asia

Abstract

Abstract:The decrease of river runoff draining into Lake Balkhash in Central Asia was investigated using hydrological and meteorological data over a long-term period. The data from the difference integral curves of the annual runoff from 1911 to 1986 suggested that a low-flow period began in 1970 in the River Ili, and in 1973 in the east rivers, continuing until 1986. Compared with the runoff before 1969, the decrease of runoff in the upper reaches of the River Ili was less than those in the middle and lower reaches. The decrease in the upper reaches resulted from natural variability, whereas those of the middle and lower reaches were due to a combination of the effects of climate and human activity. There are two reasons for this. First, after 1970, precipitation did not decrease uniformly across the entire basin. Second, in 1970, the Kapchagay dam started operating. As a result, the annual inflow into Lake Balkhash from the River Ili after 1970 decreased to 77% of the pre-1969 mean. Similarly, after 1973, the inflow from the east rivers was 75% of the pre-1972 mean.The characteristics of the runoff in the growing season (April to September) and those in the non-growing season (October to March) were investigated for the upper, middle, and lower reaches of the River Ili. In all reaches, the runoff in the non-growing season remained unchanged both before and after 1969. However, from 1970 to 1986, decreases of river flow in the growing season were 2Ð0 to 2Ð5 times greater in the middle and lower reaches than in the upper reaches. This was primarily due to the impacts of human activity. In conclusion, it can be deduced that the decrease in runoff after 1970 in the middle and lower reaches was the result of human activity during the low-flow period.

Essentials of Endorheic Basins and Lakes: A Review in the Context of Current and Future Water Resource Management and Mitigation Activities in Central Asia

“…It belongs to a basin shared with China and Kyrgyzstan, with a watershed area of more than 400,000 km 2 [50]. The inflow to the lake stems from runoff and streamflow generated in the Tien Shan and Dzungar Alatau Mountains with the Ili River supplying about 80% of all water, while the remaining water comes from the Karatal, Aksu, Lepcy, and Ayaguz Rivers [25,50,51]. The Ili River flow to Balkhash Lake is regulated by the Kapchagay reservoir, which was constructed around 1970, both to generate electricity and to supply water for irrigation in the region [52].…”

“…On the contrary, Propastin [50], using satellite altimetry, found an increase in lake levels of more than 1.5 m between 1993 and 2005, indicating that there is uncertainty with regards to the lake's size. The main river in the Balkhash basin is the Ili River that originates in the Chinese Tien Shan, and China has progressively increased the water withdrawals from this river for irrigation [25,51]. Thus far, Kazakhstan and China have been unable to reach an agreement regarding the regulation of the Ili River flow [25].…”

Rationalization of Altitudinal Precipitation Profiles in a Data-Scarce Glacierized Watershed Simulation in the Karakoram

“…Therefore, the PLAPS has a significant impact on the outputs of the glacio-hydrological model used [9]. Studies on the impact of climate change in similar regions [6,65,66] have also revealed that precipitation differences in mountainous areas can significantly affect the temporal and spatial distributions of runoff and changes in glacier areas, mass balances and meltwater. As a result, accurately determining PLAPS is a key process in hydrological modeling.…”

Correlation Analysis of NINO3.4 SST and Inland Lake Level Variations Monitored with Satellite Altimetry: Case Studies of Lakes Hongze, Khanka, La-ang, Ulungur, Issyk-kul and Baikal

“…As temperatures increase, glaciers melt faster and the water levels of rivers and lakes rise (Kezer and Matsuyama 2006). The meteorological community uses a temperature difference of 0.5°C in the average sea surface temperature (SST) as a criterion for an ENSO event.…”