Comparative Analysis of MapSWAT and Traditional Approaches for SWAT+ Data Preparation in a Small Catchment in Thailand

Abstract

Data preparation is important in hydrological modeling because it directly affects the accuracy of water resource assessments. This study introduces MapSWAT, a new geospatial tool designed to improve data preparation for the SWAT+ (Soil and Water Assessment Tool Plus) model. MapSWAT includes advanced processes for three key tasks: physical analysis, land use classification, and soil parameter estimation. The objective of this study is to compare the outcomes of data preparation between conventional methods and the use of MapSWAT, focusing on watershed delineation, hydrologic response unit (HRU) generation, and streamflow simulation. Both approaches include steps such as watershed delineation, creating Hydrologic Response Units (HRUs), and preparing input data for the SWAT+ model and streamflow simulations. Select the Huai Phong catchment (940 km²) which is a sub-basin of the Mun River Basin in Thailand for the study. The results show that MapSWAT reduces data preparation time, especially in complex terrains. It has two versions: standard and one integrated with Google Earth Engine (GEE) for direct access to geospatial data. Using MapSWAT for watershed subdivision reduced the total watershed area by 3.2% compared to traditional methods, with a slight decrease in hydrological response units (HRUs) from 107 to 101. The water flow simulation showed higher flow rates with MapSWAT during the rainy season, with an RMSE of 15.95, demonstrating its efficiency and reliability.