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.

地下水模拟（Groundwater Modelling）是研究含水层系统（aquifer system）在各类水文胁迫下动态行为的重要管理工具。本研究以卡沃里河（Cauvery River）三角洲区域为研究区，旨在通过数值模拟估算改善地下水水质所需的最小河道径流量。卡沃里河三角洲是印度南部农业生产力最高的平原区域，但近数十年来，受河道径流量不足以及东部区域地下水中溶质浓度持续升高的影响，当地农业活动已出现衰减。为探明溶质浓度升高的成因，本研究构建了三层有限差分水流模型（finite-difference flow model），用于模拟地下水位水头（groundwater head）与溶质运移（solute transport）过程。利用该模型对2007年7月至2012年6月共5年的地下水流与溶质运移过程进行了模拟。模拟计算得到的地下水位水头与实测值之间吻合度较好。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序变化与模拟结果具有较好的一致性。2007年7月至2012年6月的溶质浓度模拟结果显示，研究区沿海区域地下水中溶质出现累积现象。本研究利用该模型确定了需维持的河道径流量，以及将离子冲入海洋所需的降雨补给量。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资源可持续利用意识来实现上述目标。