Y.S. Yang

Multi-objective optimization for sustainable groundwater resource management in a semiarid catchment

Abstract Groundwater is an important water resource and its management is vital for integrated water resources development in semiarid catchments. The River Shiyang catchment in the semiarid area of northwestern China was studied to determine a sustainable multi-objective management plan of water resources. A multi-objective optimization model was developed which incorporated water supplies, groundwater quality, ecology, environment and economics on spatial and temporal scales under various detailed constraints. A calibrated groundwater flow model was supplemented by grey simulation of groundwater quality, thus providing two lines of evidence to use in the multi-objective water management. The response matrix method was used to link the groundwater simulation models and the optimization model. Multi-phase linear programming was used to minimize and compromise the objectives for the multi-period, conjunctive water use optimization model. Based on current water demands, this water use optimization management plan was able to meet ecological, environmental and economic objectives, but did not find a final solution to reduce the overall water deficit within the catchment.

Characterizing a heterogeneous hydrogeological system using groundwater flow and geochemical modelling

Characterization of heterogeneous hydrogeological systems plays an important role in groundwater protection and remediation of contaminated sites. However, sparse field observations and/or lack of relevant in situ test results hinder regional characterization process. In such cases, advanced modelling techniques can improve characterization of such complex hydrogeological systems. A sequential approach using groundwater flow modelling with nonlinear inverse calibration, advective transport and geochemical modelling and isotope study to characterize heterogeneous systems has been developed in this case study. It was used to better understand the regional hydrogeology and groundwater system of the Triassic Sherwood Sandstone aquifer underlying the Belfast area, Northern Ireland. Based on the inversely calibrated flow model and advective transport modelling by particle tracking, geochemical interpretation of groundwater quality data and isotopic and geochemical inverse modelling at well-distributed spatial locations in the sandstone were carried out to verify the flow pathways and residence times and to identify the geochemical evolution in this heterogeneous hydrogeological system. These approaches provide multiple lines of evidence for characterization of the heterogeneous aquifer system. The flowpaths and residence times from the flow and advective transport modelling agreed well with the geochemical modelling and isotopic radiocarbon dating. This demonstrates the importance of incorporating both flow and geochemical analysis techniques in a hydrogeological study.

The Triassic Sherwood Sandstone aquifer in Northern Ireland: constraint of a groundwater flow model for resource management

Abstract The most important aquifer in Northern Ireland is the Triassic Sherwood Sandstone formation that lies under the urban area of Belfast and the areas to the east (Newtownards) and south (Lagan Valley) of the city. The management of this groundwater resource is important in providing a sustainable supply for both public and industrial users. A groundwater flow model that collated relevant meteorological, hydrological and hydrogeological information for the Lagan Valley and Newtownards areas was developed. This conceptual model was coupled with geochemical and isotopic data (using inverse modelling) to constrain the groundwater flow parameters. The results of 14C-dating suggest some of the groundwater in the aquifer may be up to 4000 years old, and that structural controls play a major role in both the flow rate and the spatial distribution of groundwater within the Sherwood Sandstone aquifer.