Tamne catchment has a river system, a reservoir, and fertile arable land, making it a valuable landscape in the northern part of Ghana. Tamne catchment’s water flow is crucial, and long-term spatio-temporal assessment from 1992 to 2022 to understand inter-decadal variability is essential for supporting water management and agriculture in the catchment. The study used geospatial and climate data and applied the SWAT model and Mann-Kendall test with Sen's slope to assess key climatic and LULC variables. The results showed that water increased by 1%, built/bare soil areas increased by 26% while grass/shrub land decreased by 31% from 1992-2022, and agricultural land saw a decline by 37% and 28% between 2002 and 2022. Climate and LULC shifts increased evapotranspiration and led to decreasing trends in groundwater and surface discharge. Trend analysis of rainfall indicated a troubling decline in rainfall with a Sen's slope of -5.24, highlighting variability in the annual rainfall but insignificantly affects the catchment hydrology. The SWAT model performed well, supported with an NSE of 0.71 and robust P- and R-factor values of 0.75 and 0.78, respectively.