GroMoPo Metadata for Mendha sub-basin model

A direct approach to designing MODFLOW finite difference model is tedious and less intuitive, specifically for complex boundary and initial conditions. Therefore, a MODFLOW model can be developed either using a grid or conceptual model approach. The conceptual model is created using Geographic Information System (GIS) objects including points, arcs and polygons so that it can more accurately represent real world condition. It is a simplified representation of the site to be modelled including the model domain, boundary conditions, sources, sinks and material zones. Advantage of conceptual model is that most of the input can be in terms of physical objects, such as wells, lakes, recharge zones etc which can then be converted to a grid based mathematical model with the help of preprocessor software. This paper presents the results of a mathematical groundwater model developed for the northern part of Mendha sub-basin in the semi arid region of northeastern Rajasthan, employing conceptual groundwater modelling approach. For this purpose, Groundwater Modelling Software (GMS) was used which supports the MODFLOW-2000 code. For the purpose of modelling the Source/ Sink Coverage, Recharge Coverage, Extraction Coverage, Return Flow Coverage and Soil Coverage were considered. The model was calibrated against the historical and observed water level data for periods 1998 to 2003 and 2003 to 2005 respectively. The model was calibrated using observed water level data collected during the study period, so that model is capable to producing field measured heads and flow. For the present study historical data of water level is divided into two parts, in the first part of data from year 1998 to 2003 were used for the calibration purpose. In the second part the available field data during year 2003 to 2005 were used for model verification. The model was run to generate groundwater scenario for a 15 year period from 2006 to 2020 considering the existing rate of groundwater draft and recharge. The water budget predictions indicate a decrease from 349.50 to 222.90 MCM in the groundwater storage system, whereas groundwater abstraction shows an increase from 258.69 to 358.74 MCM per annum. The predicted water table contour maps for the years 2007, 2015 and 2020 have also been generated.直接设计MODFLOW有限差分模型的方法繁琐且直观性不足，尤其在处理复杂边界与初始条件时更为突出。因此，MODFLOW模型可通过网格法或概念模型法进行开发。概念模型借助地理信息系统（Geographic Information System，简称GIS）对象（包括点、弧段与多边形）构建，能够更精准地还原真实水文地质条件。该模型是待模拟区域的简化表征，涵盖模拟域、边界条件、源汇项与物质分区等核心要素。概念模型的优势在于，多数输入项可采用实体对象形式呈现，例如井、湖泊、补给区等，随后可通过预处理软件将其转换为基于网格的数学模型。本文针对拉贾斯坦邦东北部半干旱地区的门达（Mendha）子流域北部区域，采用概念性地下水建模方法开发了数学地下水模型，并展示其模拟成果。本次研究使用支持MODFLOW-2000代码的地下水模拟软件（Groundwater Modelling Software，简称GMS）开展建模工作。为模拟源汇项覆盖范围，本次研究纳入了补给覆盖区、开采覆盖区、回灌覆盖区与土壤覆盖区。模型分别以1998—2003年、2003—2005年的历史实测水位数据进行率定与验证，其中1998—2003年的水位数据用于模型率定，2003—2005年的实测数据则用于模型验证，确保模型能够复现野外实测的水头与流场。基于当前地下水开采与补给速率，模型运行生成了2006—2020年共15年的地下水情景模拟结果。水均衡预测结果显示，地下水储水量将从349.50 MCM逐年减少至222.90 MCM，而地下水年开采量则从258.69 MCM增长至358.74 MCM。此外，研究还生成了2007年、2015年与2020年的预测地下水位等值线图。