GroMoPo Metadata for Cauvery River MODFLOW model

Groundwater modelling is an important management tool to study the behaviour of aquifer system under various hydrological stresses. Present study was carried out in deltaic regions of the Cauvery river, with an objective of estimating the minimum river flow required to improve the groundwater quality by numerical modelling. Cauvery river delta is the most productive agricultural plains of south India, but the agricultural activities during the last few decades have decreased due to limited flow in the river and increasing concentration of solutes in groundwater in the eastern parts. In order to understand the causes for increasing concentration, a three-layered finite-difference flow model was formulated to simulate the groundwater head and solute transport. The model was used to simulate the groundwater flow and solute transport for 5 years from July 2007 to June 2012. There was a fairly good agreement between the computed and observed groundwater heads. The chloride and nitrate ions were considered for solute transport modelling. Observed and simulated temporal variation in chloride and nitrate concentrations were comparable. The simulated solute concentrations from July 2007 to June 2012 showed an accumulation of solutes in groundwater of coastal part of the study area. The model was used to find the flow to be maintained in the river and rainfall recharge required to flush the ions into the sea. This can be achieved by maintaining minimal flow in the river and through regulation of fertilizer use as well as by creating awareness of sustainable use of groundwater in this area.

地下水建模是研究含水层系统在各类水文胁迫下动态行为的重要管理工具。本研究以卡维里河（Cauvery）三角洲区域为研究对象，旨在通过数值建模估算改善地下水水质所需的最小河道径流量。卡维里河三角洲是印度南部农业产出最高的平原区域，但近数十年来，由于河道径流量不足，且东部区域地下水中溶质浓度持续升高，当地农业活动已出现衰退。为探明溶质浓度升高的成因，本研究构建了三层有限差分流模型，用于模拟地下水水头与溶质运移过程。该模型被用于模拟2007年7月至2012年6月共5年的地下水流与溶质运移过程。模拟得到的地下水水头与实测值吻合度较好。溶质运移模拟选取氯离子与硝酸根离子作为模拟对象。氯离子与硝酸根浓度的实测时间变化与模拟结果较为匹配。2007年7月至2012年6月的模拟溶质浓度结果显示，研究区沿海区域地下水中出现溶质累积现象。本研究利用该模型确定了维持河道径流量与降雨补给量的最优值，以将离子冲刷入海。可通过维持河道最小径流量、规范化肥使用，以及提升该区域地下水可持续利用意识来实现上述目标。