A Method to Assess the Effects of Climatic Warming on the Water Balance of Mountainous Regions

From a regional perspective, systematic vertical variations of the mean annual water balance components (precipitation, evaporation and runoff) are characteristic features of mountainous terrain. For nonglacierized areas, vertical distribution of runoff can be obtained as the difference between measured precipitation and evaporation calculated using such equations as that proposed by Turc. Turc’s equation makes use of temperature and precipitation as the input variables, and is well suited to the study of regional water balance impacts due to climatic warming. Using this equation and the water balance relationship, evaporation and runoff from various elevation zones of Mt. Emei in southwestern China were computed. A 4°C temperature rise scenario was applied to the region and this caused a rise in evaporation accompanied by a reduction in runoff at all elevations. The proposed method is simple to use and allows an assessment of the sensitivity of the water balance variables to temperature and precipitation changes.