Investigation of Hydro-Climatic and Vegetation Cover Trends and Complexities Effects on Water Table Using Wavelet-Entropy and Mann-Kendall

The present study aims at investigating the trend and energy complexity of hydro-climatic parameters including discharge, precipitation and temperature and Vegetation Cover (VC) in Zilbierchay catchment, East Azerbaijan, where water table has experienced a sharp drop in recent years. To this end, the water table (over 18 years interval), discharge, precipitation, temperature and VC (over 30 year interval) were examined using Mann-Kendall trend in monthly and yearly scales. The parameters were decomposed using Daubechies mother wavelet (db2) analysis at three 10-intervals and 5 time levels. The results indicated that the reduction of water table and discharge were significant. On the other hand, no significant trend was detected in precipitation and VC, while for temperature, significant increasing trends were observed in most of the months. The result of the complexity analysis revealed that the changes in the complexity of temperature (about 2% increase) were not significant, while the fluctuations reduction was found in precipitation (about 20%). In addition the pattern of fluctuations has changed which affected the complexity reduction of discharge (17%) and depth to the water table (13%). Furthermore, increasing vegetation cover area and temperature through raised evapotranspiration as well as reduced discharge and precipitation in the region have increased the drastic use of groundwater. Therefore, considering the complex relationships and synergistic effects of natural and human factors on water resources together can help managers in optimal and efficient decision making.