Simple model for monitoring Balkhash Lake water levels and Ili River discharges: Application of remote sensing
Balkhash Lake and its environs are a very fragile ecosystem, whose dynamics exhibits large oscillations in magnitude caused by climatic factors and human impacts. The most recent oscillation was accompanied by construction of a water storage reservoir on the Ili River, the main inflow to the lake, leading to an additional decrease in the Balkhash Lake water level, and to dehydration of wetland landscapes in the Ili River delta. The main purpose of this study was to model the link between wetland biomass conditions in the Ili River delta and changes in the Balkhash Lake water level. A monthly, coarse-resolution Normalized Difference Vegetation Index (NDVI) dataset was used as an indicator of vegetation activity and biomass dynamics in the Ili River delta wetland for the period between 1982 and 2003. The NDVI displays significant intra-annual and interannual variability strongly correlated with Ili River discharge and Balkhash Lake water level. This study also developed a simple model between NDVI and the two hydrological variables used in monitoring the hydrological regime of Balkhash Lake and its catchment basin.