This paper evaluates the feasibility of applying a coupled melt, runoff, and mass balance model to the tropical Zongo glacier (Cordillera Real, Bolivia) during two hydrological years. Melt rate was estimated using the standard degree-day method (DDM) and an enhanced temperature-index model (ETI). The latter was run with values of parameters obtained for Haut Glacier d’Arolla and a recalibrated parameter set for Zongo glacier. Glacier mass balance was calculated using snowfall inputs and modelled melt and sublimation. Estimated monthly mass balance and discharge were compared with observations from a stake network in the ablation zone and data from a hydrometric station. We concluded that ETI model agrees very well with the reference runoff and mass balance. Net mass balance over the whole glacier was predicted accurately in the ablation zone, but the model overestimated mass balance in the accumulation zone owing to the absence of observations at higher elevations; the equilibrium line altitude and accumulation area ratio were predicted within reasonable limits. The results demonstrate that ETI model is applicable in tropical conditions, provided that the parameters are recalibrated for the climatic settings of this region.
This paper presents a comprehensive analysis of sea level variations around the Mekong Delta, and their causes and consequences on the environment, based on the tidal records from several stations. The results of the analysis revealed significant spatio-temporal sea level variations along the delta coast. Tidal fluctuations showed their local peaks around the river mouth with shallow bottom areas. The prevailing winds were identified as the factor governing the remarkable seasonal variability of the mean sea levels along the southern coast of the delta. From 1985 to 2010, the relative sea level along the southern coast of the delta rose by about 3.3 mm y–1. This rate of rise combined with the effect of land subsidence renders the Mekong Delta alarmingly susceptible to frequent inundation. Moreover, the immediate impacts, including saline intrusion and occasional inundation due to seasonal sea level fluctuation, are also found to be critical and require urgent attention. These findings suggest the need to revise coastal management strategies to prioritize the immediate effects of short-term sea level fluctuations and to increase the focus on local management issues such as groundwater pumping causing land subsidence and local sea level trends in addition to the global threats.
In arid/semi-arid regions, consumption of deep groundwater resources is increasing due to growing water demand in every sector. Intensive groundwater surveys focused on the Baiyangdian Lake Watershed (BLW) in the northwest of the North China Plain, as the BLW suffers from serious water problems due to high economic growth and improper groundwater resource utilization. To clarify the interaction between shallow and deep groundwater, samples of surface water and groundwater in different aquifers were collected from two cities (Baoding City and Dingzhou City). Major trace element solute ion concentrations and stable isotopes of δ18O and δ2H revealed that, in a specific region of Baoding, anthropogenic activities have induced interaquifer recharge from Aquifer 1 to Aquifer 2 based on the similarity in chemical tracers. However, such an interaction could not be found in other regions in the study area.
The surface water/groundwater-continuum flow system is investigated through an intensive field survey downstream of the Baiyangdian Lake watershed, North China Plain. Oxygen and hydrogen isotope and chemical analyses are conducted on surface water, shallow groundwater, and deep groundwater and the results are processed by applying principal component and cluster analyses. The surface water of the Fu River, Tang Reservoir, and Baiyangdian Lake is strongly affected by anthropogenic influence, resulting in high nitrate-ion concentration, a distinct sodium-sulfate water-type derived from industrial wastewater, and enriched stable isotopic compositions due to accumulated evaporation, respectively. In some areas, shallow groundwater shows close chemical and isotopic affinity to surface water, indicating that surface water recharges to shallow groundwater. Deep groundwater shows lower chemical and isotopic signals than surface water and shallow groundwater. However, a slightly high nitrate-ion concentration is observed in some samples of deep groundwater, suggesting a partial communication between shallow and deep aquifers.